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Sample records for rat skeletal-muscle mitochondrial

  1. Melanocortin 4 Receptor Activation Attenuates Mitochondrial Dysfunction in Skeletal Muscle of Diabetic Rats.

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    Zhang, Hao-Hao; Liu, Jiao; Qin, Gui-Jun; Li, Xia-Lian; Du, Pei-Jie; Hao, Xiao; Zhao, Di; Tian, Tian; Wu, Jing; Yun, Meng; Bai, Yan-Hui

    2017-11-01

    A previous study has confirmed that the central melanocortin system was able to mediate skeletal muscle AMP-activated protein kinase (AMPK) activation in mice fed a high-fat diet, while activation of the AMPK signaling pathway significantly induced mitochondrial biogenesis. Our hypothesis was that melanocortin 4 receptor (MC4R) was involved in the development of skeletal muscle injury in diabetic rats. In this study, we treated diabetic rats intracerebroventricularly with MC4R agonist R027-3225 or antagonist SHU9119, respectively. Then, we measured the production of reactive oxygen species (ROS), the levels of malondialdehyde (MDA) and glutathione (GSH), the mitochondrial DNA (mtDNA) content and mitochondrial biogenesis, and the protein levels of p-AMPK, AMPK, peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC-1α), sirtuin 1 (SIRT1), and manganese superoxide dismutase (MnSOD) in the skeletal muscle of diabetic rats. The results showed that there was significant skeletal muscle injury in the diabetic rats along with serious oxidative stress and decreased mitochondrial biogenesis. Treatment with R027-3225 reduced oxidative stress and induced mitochondrial biogenesis in skeletal muscle, and also activated the AMPK-SIRT1-PGC-1α signaling pathway. However, diabetic rats injected with MC4R antagonist SHU9119 showed an aggravated oxidative stress and mitochondrial dysfunction in skeletal muscle. In conclusion, our results revealed that MC4R activation was able to attenuate oxidative stress and mitochondrial dysfunction in skeletal muscle induced by diabetes partially through activating the AMPK-SIRT1-PGC-1α signaling pathway. J. Cell. Biochem. 118: 4072-4079, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  2. The effects of methylmercury on the mitochondrial energetics of rat skeletal muscle

    International Nuclear Information System (INIS)

    Kuwabara, Takeo; Yuasa, Tatsuhiko; Nagashima, Masaru; Igarashi, Hironaka; Yonemochi, Yousuke; Atsumi, Tetsushi; Miyatake, Tadashi

    1989-01-01

    In this report it is shown that methylmercury chloride (MMC) affected the mitochondrial energetics of rat skeletal muscles in case of chronic intoxication. High energy phosphate compounds were measured by 31 P-NMR spectroscopy in the living rat hindleg skeletal muscle. Decreased value of phosphocreatine (PCr)/inorganic phosphate (Pi) ratio was observed in the resting muscle of the MMC intoxicated group, and suspend recovery of the ATP, PCr and intracellular pH after muscle contraction was found in the MMC intoxicated muscle. There was no difference in the ATP levels of the resting muscle between the control and MMC group. These results suggested that the synthesis of ATP was disturbed by the inhibition of mitochondrial respiration below TCA cycle. (author)

  3. Naked mole-rats maintain healthy skeletal muscle and Complex IV mitochondrial enzyme function into old age.

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    Stoll, Elizabeth A; Karapavlovic, Nevena; Rosa, Hannah; Woodmass, Michael; Rygiel, Karolina; White, Kathryn; Turnbull, Douglass M; Faulkes, Chris G

    2016-12-19

    The naked mole-rat (NMR) Heterocephalus glaber is an exceptionally long-lived rodent, living up to 32 years in captivity. This extended lifespan is accompanied by a phenotype of negligible senescence, a phenomenon of very slow changes in the expected physiological characteristics with age. One of the many consequences of normal aging in mammals is the devastating and progressive loss of skeletal muscle, termed sarcopenia, caused in part by respiratory enzyme dysfunction within the mitochondria of skeletal muscle fibers. Here we report that NMRs avoid sarcopenia for decades. Muscle fiber integrity and mitochondrial ultrastructure are largely maintained in aged animals. While mitochondrial Complex IV expression and activity remains stable, Complex I expression is significantly decreased. We show that aged naked mole-rat skeletal muscle tissue contains some mitochondrial DNA rearrangements, although the common mitochondrial DNA deletions associated with aging in human and other rodent skeletal muscles are not present. Interestingly, NMR skeletal muscle fibers demonstrate a significant increase in mitochondrial DNA copy number. These results have intriguing implications for the role of mitochondria in aging, suggesting Complex IV, but not Complex I, function is maintained in the long-lived naked mole rat, where sarcopenia is avoided and healthy muscle function is maintained for decades.

  4. Curcumin attenuates skeletal muscle mitochondrial impairment in COPD rats: PGC-1α/SIRT3 pathway involved.

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    Zhang, Ming; Tang, Jingjing; Li, Yali; Xie, Yingying; Shan, Hu; Chen, Mingxia; Zhang, Jie; Yang, Xia; Zhang, Qiuhong; Yang, Xudong

    2017-11-01

    Curcumin has been widely used to treat numerous diseases due to its antioxidant property. The aim of the present study is to investigate the effect of curcumin on skeletal muscle mitochondria in chronic obstructive pulmonary disease (COPD) and its underlying mechanism. The rat model of COPD was established by cigarette smoke exposure combined with intratracheal administration of lipopolysaccharide. Airway inflammation and emphysema were notably ameliorated by the treatment with curcumin. Oral administration of curcumin significantly improved muscle fiber atrophy, myofibril disorganization, interstitial fibrosis and mitochondrial structure damage in the skeletal muscle of COPD rats. Mitochondrial enzyme activities of cytochrome c oxidase, succinate dehydrogenase, Na + /K + -ATPase and Ca 2+ -ATPase in skeletal muscle mitochondria from COPD rats were significantly increased after treatment with curcumin. Moreover, curcumin significantly decreased oxidative stress and inflammation by determining the levels of malondialdehyde, manganese superoxide dismutase, glutathione peroxidase, catalase, IL-6 and TNF-α in skeletal muscle of COPD rats. Furthermore, curcumin significantly increased the mRNA and protein expression of PGC-1α and SIRT3 in the skeletal muscle tissues of COPD rats. These results suggested that curcumin can attenuate skeletal muscle mitochondrial impairment in COPD rats possibly by the up-regulation of PGC-1α/SIRT3 signaling pathway. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Impaired exercise performance and skeletal muscle mitochondrial function in rats with secondary carnitine deficiency

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    Jamal BOUITBIR

    2016-08-01

    Full Text Available Purpose: The effects of carnitine depletion upon exercise performance and skeletal muscle mitochondrial function remain largely unexplored. We therefore investigated the effect of N-trimethyl-hydrazine-3-propionate (THP, a carnitine analogue inhibiting carnitine biosynthesis and renal carnitine reabsorption, on physical performance and skeletal muscle mitochondrial function in rats.Methods: Male Sprague Dawley rats were treated daily with water (control rats; n=12 or with 20 mg/100 g body weight THP (n=12 via oral gavage for 3 weeks. Following treatment, half of the animals of each group performed an exercise test until exhaustion.Results: Distance covered and exercise performance were lower in THP-treated compared to control rats. In the oxidative soleus muscle, carnitine depletion caused atrophy (-24% and impaired function of complex II and IV of the mitochondrial electron transport chain. The free radical leak (ROS production relative to oxygen consumption was increased and the cellular glutathione pool decreased. Moreover, mRNA expression of markers of mitochondrial biogenesis and mitochondrial DNA were decreased in THP-treated compared to control rats. In comparison, in the glycolytic gastrocnemius muscle, carnitine depletion was associated with impaired function of complex IV and increased free radical leak, whilst muscle weight and cellular glutathione pool were maintained. Markers of mitochondrial proliferation and mitochondrial DNA were unaffected.Conclusions: Carnitine deficiency is associated with impaired exercise capacity in rats treated with THP. THP-induced carnitine deficiency is associated with impaired function of the electron transport chain in oxidative and glycolytic muscle as well as with atrophy and decreased mitochondrial DNA in oxidative muscle.

  6. Tissue specific phosphorylation of mitochondrial proteins isolated from rat liver, heart muscle, and skeletal muscle

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    Bak, Steffen; León, Ileana R; Jensen, Ole Nørregaard

    2013-01-01

    -specific phosphorylation sites were identified in tissue-specific enzymes such as those encoded by HMGCS2, BDH1, PCK2, CPS1, and OTC in liver mitochondria, and CKMT2 and CPT1B in heart and skeletal muscle. Kinase prediction showed an important role for PKA and PKC in all tissues but also for proline-directed kinases......Phosphorylation of mitochondrial proteins in a variety of biological processes is increasingly being recognized and may contribute to the differences in function and energy demands observed in mitochondria from different tissues such as liver, heart, and skeletal muscle. Here, we used a combination...... of TiO2 phosphopeptide-enrichment, HILIC fractionation, and LC-MS/MS on isolated mitochondria to investigate the tissue-specific mitochondrial phosphoproteomes of rat liver, heart, and skeletal muscle. In total, we identified 899 phosphorylation sites in 354 different mitochondrial proteins including...

  7. Sex-Specific Skeletal Muscle Fatigability and Decreased Mitochondrial Oxidative Capacity in Adult Rats Exposed to Postnatal Hyperoxia

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    Laura H. Tetri

    2018-03-01

    Full Text Available Premature birth affects more than 10% of live births, and is characterized by relative hyperoxia exposure in an immature host. Long-term consequences of preterm birth include decreased aerobic capacity, decreased muscular strength and endurance, and increased prevalence of metabolic diseases such as type 2 diabetes mellitus. Postnatal hyperoxia exposure in rodents is a well-established model of chronic lung disease of prematurity, and also recapitulates the pulmonary vascular, cardiovascular, and renal phenotype of premature birth. The objective of this study was to evaluate whether postnatal hyperoxia exposure in rats could recapitulate the skeletal and metabolic phenotype of premature birth, and to characterize the subcellular metabolic changes associated with postnatal hyperoxia exposure, with a secondary aim to evaluate sex differences in this model. Compared to control rats, male rats exposed to 14 days of postnatal hyperoxia then aged to 1 year demonstrated higher skeletal muscle fatigability, lower muscle mitochondrial oxidative capacity, more mitochondrial damage, and higher glycolytic enzyme expression. These differences were not present in female rats with the same postnatal hyperoxia exposure. This study demonstrates detrimental mitochondrial and muscular outcomes in the adult male rat exposed to postnatal hyperoxia. Given that young adults born premature also demonstrate skeletal muscle dysfunction, future studies are merited to determine whether this dysfunction as well as reduced aerobic capacity is due to reduced mitochondrial oxidative capacity and metabolic dysfunction.

  8. Alternate-Day High-Fat Diet Induces an Increase in Mitochondrial Enzyme Activities and Protein Content in Rat Skeletal Muscle.

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    Li, Xi; Higashida, Kazuhiko; Kawamura, Takuji; Higuchi, Mitsuru

    2016-04-06

    Long-term high-fat diet increases muscle mitochondrial enzyme activity and endurance performance. However, excessive calorie intake causes intra-abdominal fat accumulation and metabolic syndrome. The purpose of this study was to investigate the effect of an alternating day high-fat diet on muscle mitochondrial enzyme activities, protein content, and intra-abdominal fat mass in rats. Male Wistar rats were given a standard chow diet (CON), high-fat diet (HFD), or alternate-day high-fat diet (ALT) for 4 weeks. Rats in the ALT group were fed a high-fat diet and standard chow every other day for 4 weeks. After the dietary intervention, mitochondrial enzyme activities and protein content in skeletal muscle were measured. Although body weight did not differ among groups, the epididymal fat mass in the HFD group was higher than those of the CON and ALT groups. Citrate synthase and beta-hydroxyacyl CoA dehydrogenase activities in the plantaris muscle of rats in HFD and ALT were significantly higher than that in CON rats, whereas there was no difference between HFD and ALT groups. No significant difference was observed in muscle glycogen concentration or glucose transporter-4 protein content among the three groups. These results suggest that an alternate-day high-fat diet induces increases in mitochondrial enzyme activities and protein content in rat skeletal muscle without intra-abdominal fat accumulation.

  9. Changes in mitochondrial perilipin 3 and perilipin 5 protein content in rat skeletal muscle following endurance training and acute stimulated contraction.

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    Ramos, S V; Turnbull, P C; MacPherson, R E K; LeBlanc, P J; Ward, W E; Peters, S J

    2015-04-01

    What is the central question of this study? The aim was to determine whether mitochondrial protein content of perilipin 3 (PLIN3) and perilipin 5 (PLIN5) is increased following endurance training and whether mitochondrial PLIN5 protein is increased to a greater extent in endurance-trained rats when compared with sedentary rats following acute contraction. What is the main finding and its importance? Mitochondrial PLIN3 but not PLIN5 protein was increased in endurance-trained compared with sedentary rats, suggesting a mitochondrial role for PLIN3 due to chronic exercise. Contrary to our hypothesis, acute mitochondrial PLIN5 protein was similar in both sedentary and endurance-trained rats. Endurance training results in an increased association between skeletal muscle lipid droplets and mitochondria. This association is likely to be important for the expected increase in intramuscular fatty acid oxidation that occurs with endurance training. The perilipin family of lipid droplet proteins, PLIN(2-5), are thought to play a role in skeletal muscle lipolysis. Recently, results from our laboratory demonstrated that skeletal muscle mitochondria contain PLIN3 and PLIN5 protein. Furthermore, 30 min of stimulated contraction induces an increased mitochondrial PLIN5 content. To determine whether mitochondrial content of PLIN3 and PLIN5 is altered with endurance training, Sprague-Dawley rats were randomized into sedentary or endurance-trained groups for 8 weeks of treadmill running followed by an acute (30 min) sciatic nerve stimulation to induce lipolysis. Mitochondrial PLIN3 protein was ∼1.5-fold higher in red gastrocnemius of endurance-trained rats compared with sedentary animals, with no change in mitochondrial PLIN5 protein. In addition, there was an increase in plantaris intramuscular lipid storage. Acute electrically stimulated contraction in red gastrocnemius from sedentary and endurance-trained rats resulted in a similar increase of mitochondrial PLIN5 between

  10. Cardiac, Skeletal, and smooth muscle mitochondrial respiration

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    Park, Song-Young; Gifford, Jayson R; Andtbacka, Robert H I

    2014-01-01

    , skeletal, and smooth muscle was harvested from a total of 22 subjects (53±6 yrs) and mitochondrial respiration assessed in permeabilized fibers. Complex I+II, state 3 respiration, an index of oxidative phosphorylation capacity, fell progressively from cardiac, skeletal, to smooth muscle (54±1; 39±4; 15......±1 pmol•s(-1)•mg (-1), prespiration rates were normalized by CS (respiration...... per mitochondrial content), oxidative phosphorylation capacity was no longer different between the three muscle types. Interestingly, Complex I state 2 normalized for CS activity, an index of non-phosphorylating respiration per mitochondrial content, increased progressively from cardiac, skeletal...

  11. Exercise-Induced Changes in Caveolin-1, Depletion of Mitochondrial Cholesterol, and the Inhibition of Mitochondrial Swelling in Rat Skeletal Muscle but Not in the Liver

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    Damian Jozef Flis

    2016-01-01

    Full Text Available The reduction in cholesterol in mitochondria, observed after exercise, is related to the inhibition of mitochondrial swelling. Caveolin-1 (Cav-1 plays an essential role in the regulation of cellular cholesterol metabolism and is required by various signalling pathways. Therefore, the aim of this study was to investigate the effect of prolonged swimming on the mitochondrial Cav-1 concentration; additionally, we identified the results of these changes as they relate to the induction of changes in the mitochondrial swelling and cholesterol in rat skeletal muscle and liver. Male Wistar rats were divided into a sedentary control group and an exercise group. The exercised rats swam for 3 hours and were burdened with an additional 3% of their body weight. After the cessation of exercise, their quadriceps femoris muscles and livers were immediately removed for experimentation. The exercise protocol caused an increase in the Cav-1 concentration in crude muscle mitochondria; this was related to a reduction in the cholesterol level and an inhibition of mitochondrial swelling. There were no changes in rat livers, with the exception of increased markers of oxidative stress in mitochondria. These data indicate the possible role of Cav-1 in the adaptive change in the rat muscle mitochondria following exercise.

  12. Molecular Mechanisms for Age-Associated Mitochondrial Deficiency in Skeletal Muscle

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    Akira Wagatsuma

    2012-01-01

    Full Text Available The abundance, morphology, and functional properties of mitochondria decay in skeletal muscle during the process of ageing. Although the precise mechanisms remain to be elucidated, these mechanisms include decreased mitochondrial DNA (mtDNA repair and mitochondrial biogenesis. Mitochondria possess their own protection system to repair mtDNA damage, which leads to defects of mtDNA-encoded gene expression and respiratory chain complex enzymes. However, mtDNA mutations have shown to be accumulated with age in skeletal muscle. When damaged mitochondria are eliminated by autophagy, mitochondrial biogenesis plays an important role in sustaining energy production and physiological homeostasis. The capacity for mitochondrial biogenesis has shown to decrease with age in skeletal muscle, contributing to progressive mitochondrial deficiency. Understanding how these endogenous systems adapt to altered physiological conditions during the process of ageing will provide a valuable insight into the underlying mechanisms that regulate cellular homeostasis. Here we will summarize the current knowledge about the molecular mechanisms responsible for age-associated mitochondrial deficiency in skeletal muscle. In particular, recent findings on the role of mtDNA repair and mitochondrial biogenesis in maintaining mitochondrial functionality in aged skeletal muscle will be highlighted.

  13. Augmentation of aerobic respiration and mitochondrial biogenesis in skeletal muscle by hypoxia preconditioning with cobalt chloride

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    Saxena, Saurabh [Experimental Biology Division, Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi, 110054 (India); Shukla, Dhananjay [Department of Biotechnology, Gitam University, Gandhi Nagar, Rushikonda, Visakhapatnam-530 045 Andhra Pradesh (India); Bansal, Anju, E-mail: anjubansaldipas@gmail.com [Experimental Biology Division, Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi, 110054 (India)

    2012-11-01

    High altitude/hypoxia training is known to improve physical performance in athletes. Hypoxia induces hypoxia inducible factor-1 (HIF-1) and its downstream genes that facilitate hypoxia adaptation in muscle to increase physical performance. Cobalt chloride (CoCl{sub 2}), a hypoxia mimetic, stabilizes HIF-1, which otherwise is degraded in normoxic conditions. We studied the effects of hypoxia preconditioning by CoCl{sub 2} supplementation on physical performance, glucose metabolism, and mitochondrial biogenesis using rodent model. The results showed significant increase in physical performance in cobalt supplemented rats without (two times) or with training (3.3 times) as compared to control animals. CoCl{sub 2} supplementation in rats augmented the biological activities of enzymes of TCA cycle, glycolysis and cytochrome c oxidase (COX); and increased the expression of glucose transporter-1 (Glut-1) in muscle showing increased glucose metabolism by aerobic respiration. There was also an increase in mitochondrial biogenesis in skeletal muscle observed by increased mRNA expressions of mitochondrial biogenesis markers which was further confirmed by electron microscopy. Moreover, nitric oxide production increased in skeletal muscle in cobalt supplemented rats, which seems to be the major reason for peroxisome proliferator activated receptor-gamma coactivator-1α (PGC-1α) induction and mitochondrial biogenesis. Thus, in conclusion, we state that hypoxia preconditioning by CoCl{sub 2} supplementation in rats increases mitochondrial biogenesis, glucose uptake and metabolism by aerobic respiration in skeletal muscle, which leads to increased physical performance. The significance of this study lies in understanding the molecular mechanism of hypoxia adaptation and improvement of work performance in normal as well as extreme conditions like hypoxia via hypoxia preconditioning. -- Highlights: ► We supplemented rats with CoCl{sub 2} for 15 days along with training. ► Co

  14. Augmentation of aerobic respiration and mitochondrial biogenesis in skeletal muscle by hypoxia preconditioning with cobalt chloride

    International Nuclear Information System (INIS)

    Saxena, Saurabh; Shukla, Dhananjay; Bansal, Anju

    2012-01-01

    High altitude/hypoxia training is known to improve physical performance in athletes. Hypoxia induces hypoxia inducible factor-1 (HIF-1) and its downstream genes that facilitate hypoxia adaptation in muscle to increase physical performance. Cobalt chloride (CoCl 2 ), a hypoxia mimetic, stabilizes HIF-1, which otherwise is degraded in normoxic conditions. We studied the effects of hypoxia preconditioning by CoCl 2 supplementation on physical performance, glucose metabolism, and mitochondrial biogenesis using rodent model. The results showed significant increase in physical performance in cobalt supplemented rats without (two times) or with training (3.3 times) as compared to control animals. CoCl 2 supplementation in rats augmented the biological activities of enzymes of TCA cycle, glycolysis and cytochrome c oxidase (COX); and increased the expression of glucose transporter-1 (Glut-1) in muscle showing increased glucose metabolism by aerobic respiration. There was also an increase in mitochondrial biogenesis in skeletal muscle observed by increased mRNA expressions of mitochondrial biogenesis markers which was further confirmed by electron microscopy. Moreover, nitric oxide production increased in skeletal muscle in cobalt supplemented rats, which seems to be the major reason for peroxisome proliferator activated receptor-gamma coactivator-1α (PGC-1α) induction and mitochondrial biogenesis. Thus, in conclusion, we state that hypoxia preconditioning by CoCl 2 supplementation in rats increases mitochondrial biogenesis, glucose uptake and metabolism by aerobic respiration in skeletal muscle, which leads to increased physical performance. The significance of this study lies in understanding the molecular mechanism of hypoxia adaptation and improvement of work performance in normal as well as extreme conditions like hypoxia via hypoxia preconditioning. -- Highlights: ► We supplemented rats with CoCl 2 for 15 days along with training. ► CoCl 2 supplementation

  15. Insulin acutely improves mitochondrial function of rat and human skeletal muscle by increasing coupling efficiency of oxidative phosphorylation.

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    Nisr, Raid B; Affourtit, Charles

    2014-02-01

    Insulin is essential for the regulation of fuel metabolism and triggers the uptake of glucose by skeletal muscle. The imported glucose is either stored or broken down, as insulin stimulates glycogenesis and ATP synthesis. The mechanism by which ATP production is increased is incompletely understood at present and, generally, relatively little functional information is available on the effect of insulin on mitochondrial function. In this paper we have exploited extracellular flux technology to investigate insulin effects on the bioenergetics of rat (L6) and human skeletal muscle myoblasts and myotubes. We demonstrate that a 20-min insulin exposure significantly increases (i) the cell respiratory control ratio, (ii) the coupling efficiency of oxidative phosphorylation, and (iii) the glucose sensitivity of anaerobic glycolysis. The improvement of mitochondrial function is explained by an insulin-induced immediate decrease of mitochondrial proton leak. Palmitate exposure annuls the beneficial mitochondrial effects of insulin. Our data improve the mechanistic understanding of insulin-stimulated ATP synthesis, and reveal a hitherto undisclosed insulin sensitivity of cellular bioenergetics that suggests a novel way of detecting insulin responsiveness of cells. © 2013.

  16. Insulin acutely improves mitochondrial function of rat and human skeletal muscle by increasing coupling efficiency of oxidative phosphorylation☆

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    Nisr, Raid B.; Affourtit, Charles

    2014-01-01

    Insulin is essential for the regulation of fuel metabolism and triggers the uptake of glucose by skeletal muscle. The imported glucose is either stored or broken down, as insulin stimulates glycogenesis and ATP synthesis. The mechanism by which ATP production is increased is incompletely understood at present and, generally, relatively little functional information is available on the effect of insulin on mitochondrial function. In this paper we have exploited extracellular flux technology to investigate insulin effects on the bioenergetics of rat (L6) and human skeletal muscle myoblasts and myotubes. We demonstrate that a 20-min insulin exposure significantly increases (i) the cell respiratory control ratio, (ii) the coupling efficiency of oxidative phosphorylation, and (iii) the glucose sensitivity of anaerobic glycolysis. The improvement of mitochondrial function is explained by an insulin-induced immediate decrease of mitochondrial proton leak. Palmitate exposure annuls the beneficial mitochondrial effects of insulin. Our data improve the mechanistic understanding of insulin-stimulated ATP synthesis, and reveal a hitherto undisclosed insulin sensitivity of cellular bioenergetics that suggests a novel way of detecting insulin responsiveness of cells. PMID:24212054

  17. Evaluation of ubiquinone concentration and mitochondrial function relative to cerivastatin-induced skeletal myopathy in rats

    International Nuclear Information System (INIS)

    Schaefer, William H.; Lawrence, Jeffery W.; Loughlin, Amy F.; Stoffregen, Dana A.; Mixson, Lori A.; Dean, Dennis C.; Raab, Conrad E.; Yu, Nathan X.; Lankas, George R.; Frederick, Clay B.

    2004-01-01

    As a class, hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors can potentially cause skeletal myopathy. One statin, cerivastatin, has recently been withdrawn from the market due to an unacceptably high incidence of rhabdomyolysis. The mechanism underlying statin-induced myopathy is unknown. This paper sought to investigate the relationship among statin-induced myopathy, mitochondrial function, and muscle ubiquinone levels. Rats were administered cerivastatin at 0.1, 0.5, and 1.0 (mg/kg)/day or dose vehicle (controls) by oral gavage for 15 days. Samples of type I-predominant skeletal muscle (soleus) and type II-predominant skeletal muscle [quadriceps and extensor digitorum longus (EDL)], and blood were collected on study days 5, 10, and 15 for morphological evaluation, clinical chemistry, mitochondrial function tests, and analysis of ubiquinone levels. No histological changes were observed in any of the animals on study days 5 or 10, but on study day 15, mid- and high-dose animals had necrosis and inflammation in type II skeletal muscle. Elevated creatine kinase (CK) levels in blood (a clinical marker of myopathy) correlated with the histopathological diagnosis of myopathy. Ultrastructural characterization of skeletal muscle revealed disruption of the sarcomere and altered mitochondria only in myofibers with degeneration, while adjacent myofibers were unaffected and had normal mitochondria. Thus, mitochondrial effects appeared not to precede myofiber degeneration. Mean coenzyme Q9 (CoQ9) levels in all dose groups were slightly decreased relative to controls in type II skeletal muscle, although the difference was not significantly different in most cases. Mitochondrial function in skeletal muscle was not affected by the changes in ubiquinone levels. The ubiquinone levels in high-dose-treated animals exhibiting myopathy were not significantly different from low-dose animals with no observable toxic effects. Furthermore, ubiquinone levels did not correlate

  18. Cryopreservation of human skeletal muscle impairs mitochondrial function

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    Larsen, Steen; Wright-Paradis, C; Gnaiger, E

    2012-01-01

    functionality after long term cryopreservation (1 year). Skeletal muscle samples were preserved in dimethyl sulfoxide (DMSO) for later analysis. Human skeletal muscle fibres were thawed and permeabilised with saponin, and mitochondrial respiration was measured by high-resolution respirometry. The capacity...

  19. ALDH2 restores exhaustive exercise-induced mitochondrial dysfunction in skeletal muscle

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    Zhang, Qiuping; Zheng, Jianheng; Qiu, Jun; Wu, Xiahong; Xu, Yangshuo; Shen, Weili; Sun, Mengwei

    2017-01-01

    Background: Mitochondrial aldehyde dehydrogenase 2 (ALDH2) is highly expressed in heart and skeletal muscles, and is the major enzyme that metabolizes acetaldehyde and toxic aldehydes. The cardioprotective effects of ALDH2 during cardiac ischemia/reperfusion injury have been recognized. However, less is known about the function of ALDH2 in skeletal muscle. This study was designed to evaluate the effect of ALDH2 on exhaustive exercise-induced skeletal muscle injury. Methods: We created transgenic mice expressing ALDH2 in skeletal muscles. Male wild-type C57/BL6 (WT) and ALDH2 transgenic mice (ALDH2-Tg), 8-weeks old, were challenged with exhaustive exercise for 1 week to induce skeletal muscle injury. Animals were sacrificed 24 h post-exercise and muscle tissue was excised. Results: ALDH2-Tg mice displayed significantly increased treadmill exercise capacity compared to WT mice. Exhaustive exercise caused an increase in mRNA levels of the muscle atrophy markers, Atrogin-1 and MuRF1, and reduced mitochondrial biogenesis and fusion in WT skeletal muscles; these effects were attenuated in ALDH2-Tg mice. Exhaustive exercise also enhanced mitochondrial autophagy pathway activity, including increased conversion of LC3-I to LC3-II and greater expression of Beclin1 and Bnip3; the effects of which were mitigated by ALDH2 overexpression. In addition, ALDH2-Tg reversed the increase of an oxidative stress biomarker (4-hydroxynonenal) and decreased levels of mitochondrial antioxidant proteins, including manganese superoxide dismutase and NAD(P)H:quinone oxidoreductase 1, in skeletal muscle induced by exhaustive exercise. Conclusion: ALDH2 may reverse skeletal muscle mitochondrial dysfunction due to exhaustive exercise by regulating mitochondria dynamic remodeling and enhancing the quality of mitochondria. - Highlights: • Skeletal muscle ALDH2 expression and activity declines during exhaustive exercise. • ALDH2 overexpression enhances physical performance and restores muscle

  20. Aberrant mitochondrial homeostasis in the skeletal muscle of sedentary older adults.

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    Adeel Safdar

    Full Text Available The role of mitochondrial dysfunction and oxidative stress has been extensively characterized in the aetiology of sarcopenia (aging-associated loss of muscle mass and muscle wasting as a result of muscle disuse. What remains less clear is whether the decline in skeletal muscle mitochondrial oxidative capacity is purely a function of the aging process or if the sedentary lifestyle of older adult subjects has confounded previous reports. The objective of the present study was to investigate if a recreationally active lifestyle in older adults can conserve skeletal muscle strength and functionality, chronic systemic inflammation, mitochondrial biogenesis and oxidative capacity, and cellular antioxidant capacity. To that end, muscle biopsies were taken from the vastus lateralis of young and age-matched recreationally active older and sedentary older men and women (N = 10/group; female symbol = male symbol. We show that a physically active lifestyle is associated with the partial compensatory preservation of mitochondrial biogenesis, and cellular oxidative and antioxidant capacity in skeletal muscle of older adults. Conversely a sedentary lifestyle, associated with osteoarthritis-mediated physical inactivity, is associated with reduced mitochondrial function, dysregulation of cellular redox status and chronic systemic inflammation that renders the skeletal muscle intracellular environment prone to reactive oxygen species-mediated toxicity. We propose that an active lifestyle is an important determinant of quality of life and molecular progression of aging in skeletal muscle of the elderly, and is a viable therapy for attenuating and/or reversing skeletal muscle strength declines and mitochondrial abnormalities associated with aging.

  1. AMPK controls exercise endurance, mitochondrial oxidative capacity, and skeletal muscle integrity

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    Lantier, Louise; Fentz, Joachim; Mounier, Rémi

    2014-01-01

    AMP-activated protein kinase (AMPK) is a sensor of cellular energy status that plays a central role in skeletal muscle metabolism. We used skeletal muscle-specific AMPKα1α2 double-knockout (mdKO) mice to provide direct genetic evidence of the physiological importance of AMPK in regulating muscle...... diminished maximal ADP-stimulated mitochondrial respiration, showing an impairment at complex I. This effect was not accompanied by changes in mitochondrial number, indicating that AMPK regulates muscle metabolic adaptation through the regulation of muscle mitochondrial oxidative capacity and mitochondrial...

  2. Cardiac, skeletal, and smooth muscle mitochondrial respiration: are all mitochondria created equal?

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    Park, Song-Young; Gifford, Jayson R; Andtbacka, Robert H I; Trinity, Joel D; Hyngstrom, John R; Garten, Ryan S; Diakos, Nikolaos A; Ives, Stephen J; Dela, Flemming; Larsen, Steen; Drakos, Stavros; Richardson, Russell S

    2014-08-01

    Unlike cardiac and skeletal muscle, little is known about vascular smooth muscle mitochondrial respiration. Therefore, the present study examined mitochondrial respiratory rates in smooth muscle of healthy human feed arteries and compared with that of healthy cardiac and skeletal muscles. Cardiac, skeletal, and smooth muscles were harvested from a total of 22 subjects (53 ± 6 yr), and mitochondrial respiration was assessed in permeabilized fibers. Complex I + II, state 3 respiration, an index of oxidative phosphorylation capacity, fell progressively from cardiac to skeletal to smooth muscles (54 ± 1, 39 ± 4, and 15 ± 1 pmol·s(-1)·mg(-1), P respiration rates were normalized by CS (respiration per mitochondrial content), oxidative phosphorylation capacity was no longer different between the three muscle types. Interestingly, complex I state 2 normalized for CS activity, an index of nonphosphorylating respiration per mitochondrial content, increased progressively from cardiac to skeletal to smooth muscles, such that the respiratory control ratio, state 3/state 2 respiration, fell progressively from cardiac to skeletal to smooth muscles (5.3 ± 0.7, 3.2 ± 0.4, and 1.6 ± 0.3 pmol·s(-1)·mg(-1), P respiration highlight the existence of intrinsic functional differences between these muscle mitochondria. This likely influences the efficiency of oxidative phosphorylation and could potentially alter ROS production.

  3. Optimizing the measurement of mitochondrial protein synthesis in human skeletal muscle.

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    Burd, Nicholas A; Tardif, Nicolas; Rooyackers, Olav; van Loon, Luc J C

    2015-01-01

    The measurement of mitochondrial protein synthesis after food ingestion, contractile activity, and/or disease is often used to provide insight into skeletal muscle adaptations that occur in the longer term. Studies have shown that protein ingestion stimulates mitochondrial protein synthesis in human skeletal muscle. Minor differences in the stimulation of mitochondrial protein synthesis occur after a single bout of resistance or endurance exercise. There appear to be no measurable differences in mitochondrial protein synthesis between critically ill patients and aged-matched controls. However, the mitochondrial protein synthetic response is reduced at a more advanced age. In this paper, we discuss the challenges involved in the measurement of human skeletal muscle mitochondrial protein synthesis rates based on stable isotope amino acid tracer methods. Practical guidelines are discussed to improve the reliability of the measurement of mitochondrial protein synthesis rates. The value of the measurement of mitochondrial protein synthesis after a single meal or exercise bout on the prediction of the longer term skeletal muscle mass and performance outcomes in both the healthy and disease populations requires more work, but we emphasize that the measurements need to be reliable to be of any value to the field.

  4. Mitochondrial function in human skeletal muscle following high-altitude exposure

    DEFF Research Database (Denmark)

    Jacobs, Robert A; Boushel, Robert; Wright-Paradis, Cynthia

    2013-01-01

    Studies regarding mitochondrial modifications in human skeletal muscle following acclimatization to high altitude are conflicting, and these inconsistencies may be due to the prevalence of representing mitochondrial function through static and isolated measurements of specific mitochondrial...... characteristics. The aim of this study, therefore, was to investigate mitochondrial function in response to high-altitude acclimatization through measurements of respiratory control in the vastus lateralis muscle. Skeletal muscle biopsies were obtained from 10 lowland natives prior to and again after a total of 9......-11 days of exposure to 4559 m. High-resolution respirometry was performed on the muscle samples to compare respiratory chain function and respiratory capacities. Respirometric analysis revealed that mitochondrial function was largely unaffected, because high-altitude exposure did not affect the capacity...

  5. Targeted overexpression of mitochondrial catalase protects against cancer chemotherapy-induced skeletal muscle dysfunction.

    Science.gov (United States)

    Gilliam, Laura A A; Lark, Daniel S; Reese, Lauren R; Torres, Maria J; Ryan, Terence E; Lin, Chien-Te; Cathey, Brook L; Neufer, P Darrell

    2016-08-01

    The loss of strength in combination with constant fatigue is a burden on cancer patients undergoing chemotherapy. Doxorubicin, a standard chemotherapy drug used in the clinic, causes skeletal muscle dysfunction and increases mitochondrial H2O2 We hypothesized that the combined effect of cancer and chemotherapy in an immunocompetent breast cancer mouse model (E0771) would compromise skeletal muscle mitochondrial respiratory function, leading to an increase in H2O2-emitting potential and impaired muscle function. Here, we demonstrate that cancer chemotherapy decreases mitochondrial respiratory capacity supported with complex I (pyruvate/glutamate/malate) and complex II (succinate) substrates. Mitochondrial H2O2-emitting potential was altered in skeletal muscle, and global protein oxidation was elevated with cancer chemotherapy. Muscle contractile function was impaired following exposure to cancer chemotherapy. Genetically engineering the overexpression of catalase in mitochondria of muscle attenuated mitochondrial H2O2 emission and protein oxidation, preserving mitochondrial and whole muscle function despite cancer chemotherapy. These findings suggest mitochondrial oxidants as a mediator of cancer chemotherapy-induced skeletal muscle dysfunction. Copyright © 2016 the American Physiological Society.

  6. Effect of temperature on fatty acid metabolism in skeletal muscle mitochondria of untrained and endurance-trained rats.

    Science.gov (United States)

    Zoladz, Jerzy A; Koziel, Agnieszka; Broniarek, Izabela; Woyda-Ploszczyca, Andrzej M; Ogrodna, Karolina; Majerczak, Joanna; Celichowski, Jan; Szkutnik, Zbigniew; Jarmuszkiewicz, Wieslawa

    2017-01-01

    We studied the effects of various assay temperatures, representing hypothermia (25°C), normothermia (35°C), and hyperthermia (42°C), on the oxidation of lipid-derived fuels in rat skeletal muscle mitochondria of untrained and endurance-trained rats. Adult 4-month-old male Wistar rats were assigned to a training group (rats trained on a treadmill for 8 weeks) or a sedentary control group. In skeletal muscle mitochondria of both control and trained rats, an increase in the assay temperature from 25°C to 42°C was accompanied by a consistent increase in the oxidation of palmitoylcarnitine and glycerol-3-phosphate. Moreover, endurance training increased mitochondrial capacity to oxidize the lipid-derived fuels at all studied temperatures. The endurance training-induced increase in mitochondrial capacity to oxidize fatty acids was accompanied by an enhancement of mitochondrial biogenesis, as shown by the elevated expression levels of Nrf2, PGC1α, and mitochondrial marker and by the elevated expression levels of mitochondrial proteins involved in fatty acid metabolism, such as fatty acid transporter CD36, carnitine palmitoyltransferase 1A (CPT1A), and acyl-CoA dehydrogenase (ACADS). We conclude that hyperthermia enhances but hypothermia attenuates the rate of the oxidation of fatty acids and glycerol-3-phosphate in rat skeletal muscle mitochondria isolated from both untrained and trained rats. Moreover, our results indicate that endurance training up-regulates mitochondrial biogenesis markers, lipid-sustained oxidative capacity, and CD36 and CPT1A proteins involved in fatty acid transport, possibly via PGC1α and Nrf2 signaling pathways.

  7. Mitochondrial dysfunction in human skeletal muscle biopsies of lipid storage disorder.

    Science.gov (United States)

    Debashree, Bandopadhyay; Kumar, Manish; Keshava Prasad, Thottethodi Subrahmanya; Natarajan, Archana; Christopher, Rita; Nalini, Atchayaram; Bindu, Parayil Sankaran; Gayathri, Narayanappa; Srinivas Bharath, Muchukunte Mukunda

    2018-02-09

    Mitochondria regulate the balance between lipid metabolism and storage in the skeletal muscle. Altered lipid transport, metabolism and storage influence the bioenergetics, redox status and insulin signalling, contributing to cardiac and neurological diseases. Lipid storage disorders (LSDs) are neurological disorders which entail intramuscular lipid accumulation and impaired mitochondrial bioenergetics in the skeletal muscle causing progressive myopathy with muscle weakness. However, the mitochondrial changes including molecular events associated with impaired lipid storage have not been completely understood in the human skeletal muscle. We carried out morphological and biochemical analysis of mitochondrial function in muscle biopsies of human subjects with LSDs (n = 7), compared to controls (n = 10). Routine histology, enzyme histochemistry and ultrastructural analysis indicated altered muscle cell morphology and mitochondrial structure. Protein profiling of the muscle mitochondria from LSD samples (n = 5) (vs. control, n = 5) by high-throughput mass spectrometric analysis revealed that impaired metabolic processes could contribute to mitochondrial dysfunction and ensuing myopathy in LSDs. We propose that impaired fatty acid and respiratory metabolism along with increased membrane permeability, elevated lipolysis and altered cristae entail mitochondrial dysfunction in LSDs. Some of these mechanisms were unique to LSD apart from others that were common to dystrophic and inflammatory muscle pathologies. Many differentially regulated mitochondrial proteins in LSD are linked with other human diseases, indicating that mitochondrial protection via targeted drugs could be a treatment modality in LSD and related metabolic diseases. © 2018 International Society for Neurochemistry.

  8. Human Milk and Donkey Milk, Compared to Cow Milk, Reduce Inflammatory Mediators and Modulate Glucose and Lipid Metabolism, Acting on Mitochondrial Function and Oleylethanolamide Levels in Rat Skeletal Muscle.

    Science.gov (United States)

    Trinchese, Giovanna; Cavaliere, Gina; De Filippo, Chiara; Aceto, Serena; Prisco, Marina; Chun, Jong Tai; Penna, Eduardo; Negri, Rossella; Muredda, Laura; Demurtas, Andrea; Banni, Sebastiano; Berni-Canani, Roberto; Mattace Raso, Giuseppina; Calignano, Antonio; Meli, Rosaria; Greco, Luigi; Crispino, Marianna; Mollica, Maria P

    2018-01-01

    Scope: Milk from various species differs in nutrient composition. In particular, human milk (HM) and donkey milk (DM) are characterized by a relative high level of triacylglycerol enriched in palmitic acid in sn-2 position. These dietary fats seem to exert beneficial nutritional properties through N-acylethanolamine tissue modulation. The aim of this study is to compare the effects of cow milk (CM), DM, and HM on inflammation and glucose and lipid metabolism, focusing on mitochondrial function, efficiency, and dynamics in skeletal muscle, which is the major determinant of resting metabolic rate. Moreover, we also evaluated the levels of endocannabinoids and N-acylethanolamines in liver and skeletal muscle, since tissue fatty acid profiles can be modulated by nutrient intervention. Procedures: To this aim, rats were fed with CM, DM, or HM for 4 weeks. Then, glucose tolerance and insulin resistance were analyzed. Pro-inflammatory and anti-inflammatory cytokines were evaluated in serum and skeletal muscle. Skeletal muscle was also processed to estimate mitochondrial function, efficiency, and dynamics, oxidative stress, and antioxidant/detoxifying enzyme activities. Fatty acid profiles, endocannabinoids, and N-acylethanolamine congeners were determined in liver and skeletal muscle tissue. Results: We demonstrated that DM or HM administration reducing inflammation status, improves glucose disposal and insulin resistance and reduces lipid accumulation in skeletal muscle. Moreover, HM or DM administration increases redox status, and mitochondrial uncoupling, affecting mitochondrial dynamics in the skeletal muscle. Interestingly, HM and DM supplementation increase liver and muscle levels of the N-oleoylethanolamine (OEA), a key regulator of lipid metabolism and inflammation. Conclusions: HM and DM have a healthy nutritional effect, acting on inflammatory factors and glucose and lipid metabolism. This beneficial effect is associated to a modulation of mitochondrial function

  9. Human Milk and Donkey Milk, Compared to Cow Milk, Reduce Inflammatory Mediators and Modulate Glucose and Lipid Metabolism, Acting on Mitochondrial Function and Oleylethanolamide Levels in Rat Skeletal Muscle

    Directory of Open Access Journals (Sweden)

    Giovanna Trinchese

    2018-01-01

    Full Text Available Scope: Milk from various species differs in nutrient composition. In particular, human milk (HM and donkey milk (DM are characterized by a relative high level of triacylglycerol enriched in palmitic acid in sn-2 position. These dietary fats seem to exert beneficial nutritional properties through N-acylethanolamine tissue modulation. The aim of this study is to compare the effects of cow milk (CM, DM, and HM on inflammation and glucose and lipid metabolism, focusing on mitochondrial function, efficiency, and dynamics in skeletal muscle, which is the major determinant of resting metabolic rate. Moreover, we also evaluated the levels of endocannabinoids and N-acylethanolamines in liver and skeletal muscle, since tissue fatty acid profiles can be modulated by nutrient intervention.Procedures: To this aim, rats were fed with CM, DM, or HM for 4 weeks. Then, glucose tolerance and insulin resistance were analyzed. Pro-inflammatory and anti-inflammatory cytokines were evaluated in serum and skeletal muscle. Skeletal muscle was also processed to estimate mitochondrial function, efficiency, and dynamics, oxidative stress, and antioxidant/detoxifying enzyme activities. Fatty acid profiles, endocannabinoids, and N-acylethanolamine congeners were determined in liver and skeletal muscle tissue.Results: We demonstrated that DM or HM administration reducing inflammation status, improves glucose disposal and insulin resistance and reduces lipid accumulation in skeletal muscle. Moreover, HM or DM administration increases redox status, and mitochondrial uncoupling, affecting mitochondrial dynamics in the skeletal muscle. Interestingly, HM and DM supplementation increase liver and muscle levels of the N-oleoylethanolamine (OEA, a key regulator of lipid metabolism and inflammation.Conclusions: HM and DM have a healthy nutritional effect, acting on inflammatory factors and glucose and lipid metabolism. This beneficial effect is associated to a modulation of

  10. Proteomic Profiling of Mitochondrial Enzymes during Skeletal Muscle Aging

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    Lisa Staunton

    2011-01-01

    Full Text Available Mitochondria are of central importance for energy generation in skeletal muscles. Expression changes or functional alterations in mitochondrial enzymes play a key role during myogenesis, fibre maturation, and various neuromuscular pathologies, as well as natural fibre aging. Mass spectrometry-based proteomics suggests itself as a convenient large-scale and high-throughput approach to catalogue the mitochondrial protein complement and determine global changes during health and disease. This paper gives a brief overview of the relatively new field of mitochondrial proteomics and discusses the findings from recent proteomic surveys of mitochondrial elements in aged skeletal muscles. Changes in the abundance, biochemical activity, subcellular localization, and/or posttranslational modifications in key mitochondrial enzymes might be useful as novel biomarkers of aging. In the long term, this may advance diagnostic procedures, improve the monitoring of disease progression, help in the testing of side effects due to new drug regimes, and enhance our molecular understanding of age-related muscle degeneration.

  11. Endurance training increases the efficiency of rat skeletal muscle mitochondria.

    Science.gov (United States)

    Zoladz, Jerzy A; Koziel, Agnieszka; Woyda-Ploszczyca, Andrzej; Celichowski, Jan; Jarmuszkiewicz, Wieslawa

    2016-10-01

    Endurance training enhances mitochondrial oxidative capacity, but its effect on mitochondria functioning is poorly understood. In the present study, the influence of an 8-week endurance training on the bioenergetic functioning of rat skeletal muscle mitochondria under different assay temperatures (25, 35, and 42 °C) was investigated. The study was performed on 24 adult 4-month-old male Wistar rats, which were randomly assigned to either a treadmill training group (n = 12) or a sedentary control group (n = 12). In skeletal muscles, endurance training stimulated mitochondrial biogenesis and oxidative capacity. In isolated mitochondria, endurance training increased the phosphorylation rate and elevated levels of coenzyme Q. Moreover, a decrease in mitochondrial uncoupling, including uncoupling protein-mediated proton leak, was observed after training, which could explain the increased reactive oxygen species production (in nonphosphorylating mitochondria) and enhanced oxidative phosphorylation efficiency. At all studied temperatures, endurance training significantly augmented H2O2 production (and coenzyme Q reduction level) in nonphosphorylating mitochondria and decreased H2O2 production (and coenzyme Q reduction level) in phosphorylating mitochondria. Endurance training magnified the hyperthermia-induced increase in oxidative capacity and attenuated the hyperthermia-induced decline in oxidative phosphorylation efficiency and reactive oxygen species formation of nonphosphorylating mitochondria via proton leak enhancement. Thus, endurance training induces both quantitative and qualitative changes in muscle mitochondria that are important for cell signaling as well as for maintaining muscle energy homeostasis, especially at high temperatures.

  12. Maternal high fat diet alters skeletal muscle mitochondrial catalytic activity in adult male rat offspring.

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    Chantal Anne Pileggi

    2016-11-01

    Full Text Available A maternal high-fat (HF diet during pregnancy can lead to metabolic compromise such as insulin resistance in adult offspring. Skeletal muscle mitochondrial dysfunction is one mechanism contributing to metabolic impairments in insulin resistant states. Therefore, the present study aimed to investigate whether mitochondrial dysfunction is evident in metabolically compromised offspring born to HF-fed dams. Sprague-Dawley dams were randomly assigned to receive a purified control diet (CD; 10% kcal from fat or a high fat diet (HFD; 45% kcal from fat for 10 days prior to mating, throughout pregnancy and during lactation. From weaning, all male offspring received a standard chow diet and soleus muscle was collected at day 150. Expression of the mitochondrial transcription factors nuclear respiratory factor-1 (NRF1 and mitochondrial transcription factor A (mtTFA were downregulated in HF offspring. Furthermore, genes encoding the mitochondrial electron transport system (ETS respiratory complex subunits were supressed in HF offspring. Moreover, protein expression of the complex I subunit, NDUFB8, was downregulated in HF offspring (36%, which was paralleled by decreased maximal catalytic linked activity of complex I and III (40%. Together, these results indicate that exposure to a maternal HF diet during development may elicit lifelong mitochondrial alterations in offspring skeletal muscle.

  13. Effect of temperature on fatty acid metabolism in skeletal muscle mitochondria of untrained and endurance-trained rats.

    Directory of Open Access Journals (Sweden)

    Jerzy A Zoladz

    Full Text Available We studied the effects of various assay temperatures, representing hypothermia (25°C, normothermia (35°C, and hyperthermia (42°C, on the oxidation of lipid-derived fuels in rat skeletal muscle mitochondria of untrained and endurance-trained rats. Adult 4-month-old male Wistar rats were assigned to a training group (rats trained on a treadmill for 8 weeks or a sedentary control group. In skeletal muscle mitochondria of both control and trained rats, an increase in the assay temperature from 25°C to 42°C was accompanied by a consistent increase in the oxidation of palmitoylcarnitine and glycerol-3-phosphate. Moreover, endurance training increased mitochondrial capacity to oxidize the lipid-derived fuels at all studied temperatures. The endurance training-induced increase in mitochondrial capacity to oxidize fatty acids was accompanied by an enhancement of mitochondrial biogenesis, as shown by the elevated expression levels of Nrf2, PGC1α, and mitochondrial marker and by the elevated expression levels of mitochondrial proteins involved in fatty acid metabolism, such as fatty acid transporter CD36, carnitine palmitoyltransferase 1A (CPT1A, and acyl-CoA dehydrogenase (ACADS. We conclude that hyperthermia enhances but hypothermia attenuates the rate of the oxidation of fatty acids and glycerol-3-phosphate in rat skeletal muscle mitochondria isolated from both untrained and trained rats. Moreover, our results indicate that endurance training up-regulates mitochondrial biogenesis markers, lipid-sustained oxidative capacity, and CD36 and CPT1A proteins involved in fatty acid transport, possibly via PGC1α and Nrf2 signaling pathways.

  14. Modulation of mitochondrial bioenergetics in a skeletal muscle cell line model of mitochondrial toxicity

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    William Dott

    2014-01-01

    Full Text Available Mitochondrial toxicity is increasingly being implicated as a contributing factor to many xenobiotic-induced organ toxicities, including skeletal muscle toxicity. This has necessitated the need for predictive in vitro models that are able to sensitively detect mitochondrial toxicity of chemical entities early in the research and development process. One such cell model involves substituting galactose for glucose in the culture media. Since cells cultured in galactose are unable to generate sufficient ATP from glycolysis they are forced to rely on mitochondrial oxidative phosphorylation for ATP generation and consequently are more sensitive to mitochondrial perturbation than cells grown in glucose. The aim of this study was to characterise cellular growth, bioenergetics and mitochondrial toxicity of the L6 rat skeletal muscle cell line cultured in either high glucose or galactose media. L6 myoblasts proliferated more slowly when cultured in galactose media, although they maintained similar levels of ATP. Galactose cultured L6 cells were significantly more sensitive to classical mitochondrial toxicants than glucose-cultured cells, confirming the cells had adapted to galactose media. Analysis of bioenergetic function with the XF Seahorse extracellular flux analyser demonstrated that oxygen consumption rate (OCR was significantly increased whereas extracellular acidification rate (ECAR, a measure of glycolysis, was decreased in cells grown in galactose. Mitochondria operated closer to state 3 respiration and had a lower mitochondrial membrane potential and basal mitochondrial O2·– level compared to cells in the glucose model. An antimycin A (AA dose response revealed that there was no difference in the sensitivity of OCR to AA inhibition between glucose and galactose cells. Importantly, cells in glucose were able to up-regulate glycolysis, while galactose cells were not. These results confirm that L6 cells are able to adapt to growth in a

  15. Impact of Resistance Training on Skeletal Muscle Mitochondrial Biogenesis, Content, and Function

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    Thomas Groennebaek

    2017-09-01

    Full Text Available Skeletal muscle metabolic and contractile properties are reliant on muscle mitochondrial and myofibrillar protein turnover. The turnover of these specific protein pools is compromised during disease, aging, and inactivity. Oppositely, exercise can accentuate muscle protein turnover, thereby counteracting decay in muscle function. According to a traditional consensus, endurance exercise is required to drive mitochondrial adaptations, while resistance exercise is required to drive myofibrillar adaptations. However, concurrent practice of traditional endurance exercise and resistance exercise regimens to achieve both types of muscle adaptations is time-consuming, motivationally demanding, and contended to entail practice at intensity levels, that may not comply with clinical settings. It is therefore of principle interest to identify effective, yet feasible, exercise strategies that may positively affect both mitochondrial and myofibrillar protein turnover. Recently, reports indicate that traditional high-load resistance exercise can stimulate muscle mitochondrial biogenesis and mitochondrial respiratory function. Moreover, fatiguing low-load resistance exercise has been shown capable of promoting muscle hypertrophy and expectedly entails greater metabolic stress to potentially enhance mitochondrial adaptations. Consequently, fatiguing low-load resistance exercise regimens may possess the ability to stimulate muscle mitochondrial adaptations without compromising muscle myofibrillar accretion. However, the exact ability of resistance exercise to drive mitochondrial adaptations is debatable, not least due to some methodological challenges. The current review therefore aims to address the evidence on the effects of resistance exercise on skeletal muscle mitochondrial biogenesis, content and function. In prolongation, a perspective is taken on the specific potential of low-load resistance exercise on promoting mitochondrial adaptations.

  16. Response of mitochondrial function to hypothyroidism in normal and regenerated rat skeletal muscle.

    Science.gov (United States)

    Zoll, J; Ventura-Clapier, R; Serrurier, B; Bigard, A X

    2001-01-01

    Although thyroid hormones induce a well known decrease in muscle oxidative capacity, nothing is known concerning their effects on mitochondrial function and regulation in situ. Similarly, the influence of regeneration process is not completely understood. We investigated the effects of hypothyroidism on mitochondrial function in fast gastrocnemius (GS) and slow soleus (SOL) muscles either intact or having undergone a cycle of degeneration/regeneration (Rg SOL) following a local injection of myotoxin. Thyroid hormone deficiency was induced by thyroidectomy and propylthiouracyl via drinking water. Respiration was measured in muscle fibres permeabilised by saponin in order to assess the oxidative capacity of the muscles and the regulation of mitochondria in situ. Oxidative capacities were 8.9 in SOL, 8.5 in Rg SOL and 5.9 micromol O2/min/g dry weight in GS and decreased by 52, 42 and 39% respectively (P hypothyroid rats. Moreover, the Km of mitochondrial respiration for the phosphate acceptor ADP exhibited a two-fold decrease in Rg SOL and intact SOL by hypothyroidism (P hypothyroidism markedly altered the sensitivity of mitochondrial respiration to ADP but not to creatine in SOL muscles, suggesting that mitochondrial regulation could be partially controlled by thyroid hormones. On the other hand, mitochondrial function completely recovered following regeneration/degeneration, suggesting that thyroid hormones are not involved in the regeneration process per se.

  17. Skeletal Muscle Fibre-Specific Knockout of p53 Does Not Reduce Mitochondrial Content or Enzyme Activity

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    Ben Stocks

    2017-12-01

    Full Text Available Tumour protein 53 (p53 has been implicated in the regulation of mitochondrial biogenesis in skeletal muscle, with whole-body p53 knockout mice displaying impairments in basal mitochondrial content, respiratory capacity, and enzyme activity. This study aimed to determine the effect of skeletal muscle-specific loss of p53 on mitochondrial content and enzyme activity. Mitochondrial protein content, enzyme activity and mRNA profiles were assessed in skeletal muscle of 8-week-old male muscle fibre-specific p53 knockout mice (p53 mKO and floxed littermate controls (WT under basal conditions. p53 mKO and WT mice displayed similar content of electron transport chain proteins I-V and citrate synthase enzyme activity in skeletal muscle. In addition, the content of proteins regulating mitochondrial morphology (MFN2, mitofillin, OPA1, DRP1, FIS1, fatty acid metabolism (β-HAD, ACADM, ACADL, ACADVL, carbohydrate metabolism (HKII, PDH, energy sensing (AMPKα2, AMPKβ2, and gene transcription (NRF1, PGC-1α, and TFAM were comparable in p53 mKO and WT mice (p > 0.05. Furthermore, p53 mKO mice exhibited normal mRNA profiles of targeted mitochondrial, metabolic and transcriptional proteins (p > 0.05. Thus, it appears that p53 expression in skeletal muscle fibres is not required to develop or maintain mitochondrial protein content or enzyme function in skeletal muscle under basal conditions.

  18. Skeletal Muscle Mitochondrial Function in Polycystic Ovarian Syndrome

    DEFF Research Database (Denmark)

    Rabøl, Rasmus; Svendsen, Pernille Maj; Skovbro, Mette

    2011-01-01

    Hyperinsulinemic euglycemic clamps (40 mU/min/m2) and muscle biopsies were performed on 23 women with PCOS (9 lean (body mass index (BMI) 25 kg/m2)) and 17 age- and weight-matched controls (6 lean and 11 obese). Western blotting and high-resolution respirometry was used to determine mitochondrial function. Results......Objective Polycystic ovarian syndrome (PCOS) is associated with skeletal muscle insulin resistance, which has been linked to decreased mitochondrial function. We measured mitochondrial respiration in lean and obese women with and without PCOS using high-resolution respirometry. Methods...... Insulin sensitivity decreased with PCOS and increasing body weight. Mitochondrial respiration with substrates for complex I and complex I+II were similar in all groups, and PCOS was not associated with a decrease in mitochondrial content as measured by mtDNA/genomicDNA. We found no correlation between...

  19. Tissue-specific and substrate-specific mitochondrial bioenergetics in feline cardiac and skeletal muscles

    DEFF Research Database (Denmark)

    Christiansen, Liselotte Bruun; Dela, Flemming; Koch, Jørgen

    2015-01-01

    fibers. Biopsies of left ventricular cardiac muscle and soleus muscle, a type I-rich oxidative skeletal muscle, were obtained from 15 healthy domestic cats. Enzymatic activity of citrate synthase (CS), a biomarker of mitochondrial content, was measured. Mitochondrial OXPHOS capacity with various kinds...

  20. Metabolic adaptations of skeletal muscle to voluntary wheel running exercise in hypertensive heart failure rats

    DEFF Research Database (Denmark)

    Schultz, R L; Kullman, E L; Waters, Ryan

    2013-01-01

    SHHF and Wistar-Furth (WF) rats were randomized to sedentary (SHHFsed and WFsed) and exercise groups (SHHFex and WFex). The exercise groups had access to running wheels from 6-22 months of age. Hindlimb muscles were obtained for metabolic measures that included mitochondrial enzyme function...... robust amounts of aerobic activity, voluntary wheel running exercise was not sufficiently intense to improve the oxidative capacity of skeletal muscle in adult SHHF animals, indicating an inability to compensate for declining heart function by improving peripheral oxidative adaptations in the skeletal...

  1. Skeletal muscle mitochondrial bioenergetics and associations with myostatin genotypes in the Thoroughbred horse.

    Science.gov (United States)

    Rooney, Mary F; Porter, Richard K; Katz, Lisa M; Hill, Emmeline W

    2017-01-01

    Variation in the myostatin (MSTN) gene has been reported to be associated with race distance, body composition and skeletal muscle fibre composition in the horse. The aim of the present study was to test the hypothesis that MSTN variation influences mitochondrial phenotypes in equine skeletal muscle. Mitochondrial abundance and skeletal muscle fibre types were measured in whole muscle biopsies from the gluteus medius of n = 82 untrained (21 ± 3 months) Thoroughbred horses. Skeletal muscle fibre type proportions were significantly (p T (C) and the SINE insertion 227 bp polymorphism (I). Evaluation of mitochondrial complex activities indicated higher combined mitochondrial complex I+III and II+III activities in the presence of the C-allele / I allele (p ≤ 0.05). The restoration of complex I+III and complex II+III activities following addition of exogenous coenzyme Q1 (ubiquinone1) (CoQ1) in vitro in the TT/NN (homozygous T allele/homozygous no insertion) cohort indicated decreased coenzyme Q in these animals. In addition, decreased gene expression in two coenzyme Q (CoQ) biosynthesis pathway genes (COQ4, p ≤ 0.05; ADCK3, p ≤ 0.01) in the TT/NN horses was observed. This study has identified several mitochondrial phenotypes associated with MSTN genotype in untrained Thoroughbred horses and in addition, our findings suggest that nutritional supplementation with CoQ may aid to restore coenzyme Q activity in TT/NN horses.

  2. Cold acclimation increases mitochondrial oxidative capacity without inducing mitochondrial uncoupling in goldfish white skeletal muscle

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    Reinaldo Sousa Dos Santos

    2012-11-01

    Goldfish have been used for cold acclimation studies, which have focused on changes in glycolytic and oxidative enzymes or alterations in lipid composition in skeletal muscle. Here we examine the effects of cold acclimation on the functional properties of isolated mitochondria and permeabilized fibers from goldfish white skeletal muscle, focusing on understanding the types of changes that occur in the mitochondrial respiratory states. We observed that cold acclimation promoted a significant increase in the mitochondrial oxygen consumption rates. Western blot analysis showed that UCP3 was raised by ∼1.5-fold in cold-acclimated muscle mitochondria. Similarly, we also evidenced a rise in the adenine nucleotide translocase content in cold-acclimated muscle mitochondria compared to warm-acclimated mitochondria (0.96±0.05 vs 0.68±0.02 nmol carboxyatractyloside mg−1 protein. This was followed by a 2-fold increment in the citrate synthase activity, which suggests a higher mitochondrial content in cold-acclimated goldfish. Even with higher levels of UCP3 and ANT, the effects of activator (palmitate and inhibitors (carboxyatractyloside and GDP on mitochondrial parameters were similar in both warm- and cold-acclimated goldfish. Thus, we propose that cold acclimation in goldfish promotes an increase in functional oxidative capacity, with higher mitochondrial content without changes in the mitochondrial uncoupling pathways.

  3. Insulin increases phosphorylation of mitochondrial proteins in human skeletal muscle in vivo

    DEFF Research Database (Denmark)

    Zhao, Xiaolu; Bak, Steffen; Pedersen, Andreas James Thestrup

    2014-01-01

    , we investigated the effect of insulin on the phosphorylation of mitochondrial proteins in human skeletal muscle in vivo. Using a combination of TiO2 phosphopeptide-enrichment, HILIC fractionation, and LC−MS/MS, we compared the phosphoproteomes of isolated mitochondria from skeletal muscle samples...... obtained from healthy individuals before and after 4 h of insulin infusion. In total, we identified 207 phosphorylation sites in 95 mitochondrial proteins. Of these phosphorylation sites, 45% were identified in both basal and insulin-stimulated samples. Insulin caused a 2-fold increase in the number...... of different mitochondrial phosphopeptides (87 ± 7 vs 40 ± 7, p = 0.015) and phosphoproteins (46 ± 2 vs 26 ± 3, p = 0.005) identified in each mitochondrial preparation. Almost half of the mitochondrial phosphorylation sites (n = 94) were exclusively identified in the insulin-stimulated state and included...

  4. Strenuous exercise induces mitochondrial damage in skeletal muscle of old mice

    International Nuclear Information System (INIS)

    Lee, Sangho; Kim, Minjung; Lim, Wonchung; Kim, Taeyoung; Kang, Chounghun

    2015-01-01

    Strenuous exercise is known to cause excessive ROS generation and inflammation. However, the mechanisms responsible for the regulation of mitochondrial integrity in the senescent muscle during high-intensity exercise (HE) are not well studied. Here, we show that HE suppresses up-regulation of mitochondrial function despite increase in mitochondrial copy number, following excessive ROS production, proinflammatory cytokines and NFκB activation. Moreover, HE in the old group resulted in the decreasing of both fusion (Mfn2) and fission (Drp1) proteins that may contribute to alteration of mitochondrial morphology. This study suggests that strenuous exercise does not reverse age-related mitochondrial damage and dysfunction by the increased ROS and inflammation. - Highlights: • Effect of exercise on mitochondrial function of aged skeletal muscles was studied. • Strenuous exercise triggered excessive ROS production and inflammatory cytokines. • Strenuous exercise suppressed mitochondrial function in senescent muscle

  5. Strenuous exercise induces mitochondrial damage in skeletal muscle of old mice

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sangho; Kim, Minjung [Department of Physical Education, Hankuk Univrsity of Foreign Studies, Seoul 130-791 (Korea, Republic of); Lim, Wonchung [Department of Sports Medicine, College of Health Science, Cheongju University, Cheongju 363-764 (Korea, Republic of); Kim, Taeyoung [Department of Physical Education, Hankuk Univrsity of Foreign Studies, Seoul 130-791 (Korea, Republic of); Kang, Chounghun, E-mail: kangx119@umn.edu [Department of Physical Education, Hankuk Univrsity of Foreign Studies, Seoul 130-791 (Korea, Republic of); Laboratory of Physiological Hygiene and Exercise Science, School of Kinesiology, University of Minnesota at Twin Cities, Minneapolis, MN 55455 (United States)

    2015-05-29

    Strenuous exercise is known to cause excessive ROS generation and inflammation. However, the mechanisms responsible for the regulation of mitochondrial integrity in the senescent muscle during high-intensity exercise (HE) are not well studied. Here, we show that HE suppresses up-regulation of mitochondrial function despite increase in mitochondrial copy number, following excessive ROS production, proinflammatory cytokines and NFκB activation. Moreover, HE in the old group resulted in the decreasing of both fusion (Mfn2) and fission (Drp1) proteins that may contribute to alteration of mitochondrial morphology. This study suggests that strenuous exercise does not reverse age-related mitochondrial damage and dysfunction by the increased ROS and inflammation. - Highlights: • Effect of exercise on mitochondrial function of aged skeletal muscles was studied. • Strenuous exercise triggered excessive ROS production and inflammatory cytokines. • Strenuous exercise suppressed mitochondrial function in senescent muscle.

  6. Dietary fat influences the expression of contractile and metabolic genes in rat skeletal muscle.

    Directory of Open Access Journals (Sweden)

    Wataru Mizunoya

    Full Text Available Dietary fat plays a major role in obesity, lipid metabolism, and cardiovascular diseases. To determine whether the intake of different types of dietary fats affect the muscle fiber types that govern the metabolic and contractile properties of the skeletal muscle, we fed male Wistar rats with a 15% fat diet derived from different fat sources. Diets composed of soybean oil (n-6 polyunsaturated fatty acids (PUFA-rich, fish oil (n-3 PUFA-rich, or lard (low in PUFAs were administered to the rats for 4 weeks. Myosin heavy chain (MyHC isoforms were used as biomarkers to delineate the skeletal muscle fiber types. Compared with soybean oil intake, fish oil intake showed significantly lower levels of the fast-type MyHC2B and higher levels of the intermediate-type MyHC2X composition in the extensor digitorum longus (EDL muscle, which is a fast-type dominant muscle. Concomitantly, MyHC2X mRNA levels in fish oil-fed rats were significantly higher than those observed in the soybean oil-fed rats. The MyHC isoform composition in the lard-fed rats was an intermediate between that of the fish oil and soybean oil-fed rats. Mitochondrial uncoupling protein 3, pyruvate dehydrogenase kinase 4, and porin mRNA showed significantly upregulated levels in the EDL of fish oil-fed rats compared to those observed in soybean oil-fed and lard-fed rats, implying an activation of oxidative metabolism. In contrast, no changes in the composition of MyHC isoforms was observed in the soleus muscle, which is a slow-type dominant muscle. Fatty acid composition in the serum and the muscle was significantly influenced by the type of dietary fat consumed. In conclusion, dietary fat affects the expression of genes related to the contractile and metabolic properties in the fast-type dominant skeletal muscle, where the activation of oxidative metabolism is more pronounced after fish oil intake than that after soybean oil intake.

  7. The HO-1/CO system regulates mitochondrial-capillary density relationships in human skeletal muscle.

    Science.gov (United States)

    Pecorella, Shelly R H; Potter, Jennifer V F; Cherry, Anne D; Peacher, Dionne F; Welty-Wolf, Karen E; Moon, Richard E; Piantadosi, Claude A; Suliman, Hagir B

    2015-10-15

    The heme oxygenase-1 (HO-1)/carbon monoxide (CO) system induces mitochondrial biogenesis, but its biological impact in human skeletal muscle is uncertain. The enzyme system generates CO, which stimulates mitochondrial proliferation in normal muscle. Here we examined whether CO breathing can be used to produce a coordinated metabolic and vascular response in human skeletal muscle. In 19 healthy subjects, we performed vastus lateralis muscle biopsies and tested one-legged maximal O2 uptake (V̇o2max) before and after breathing air or CO (200 ppm) for 1 h daily for 5 days. In response to CO, there was robust HO-1 induction along with increased mRNA levels for nuclear-encoded mitochondrial transcription factor A (Tfam), cytochrome c, cytochrome oxidase subunit IV (COX IV), and mitochondrial-encoded COX I and NADH dehydrogenase subunit 1 (NDI). CO breathing did not increase V̇o2max (1.96 ± 0.51 pre-CO, 1.87 ± 0.50 post-CO l/min; P = not significant) but did increase muscle citrate synthase, mitochondrial density (139.0 ± 34.9 pre-CO, 219.0 ± 36.2 post-CO; no. of mitochondrial profiles/field), myoglobin content and glucose transporter (GLUT4) protein level and led to GLUT4 localization to the myocyte membrane, all consistent with expansion of the tissue O2 transport system. These responses were attended by increased cluster of differentiation 31 (CD31)-positive muscle capillaries (1.78 ± 0.16 pre-CO, 2.37 ± 0.59 post-CO; capillaries/muscle fiber), implying the enrichment of microvascular O2 reserve. The findings support that induction of the HO-1/CO system by CO not only improves muscle mitochondrial density, but regulates myoglobin content, GLUT4 localization, and capillarity in accordance with current concepts of skeletal muscle plasticity. Copyright © 2015 the American Physiological Society.

  8. Effects of exercise training and exhaustion on 45Ca uptake by rat skeletal muscle mitochondria and sarcoplasmic reticulum

    International Nuclear Information System (INIS)

    Bonner, H.W.; Leslie, S.W.; Combs, A.B.; Tate, C.A.

    1976-01-01

    Mitochondrial and sarcoplasmic reticular 45 Ca 2+ uptake and Ca 2+ -ATPase activity were determined in skeletal muscle from exercise trained and non-trained rats at rest or following short-term exhaustive exercise. In trained rats exercised to exhaustion, mitochondrial 45 Ca 2+ uptake was significantly depressed when compared to non-trained rats at rest. Ca 2+ -ATPase activity of sarcoplasmic reticulum from trained rats exercised to exhaustion was significantly increased as compared to trained rats at rest. These data suggest that the disruptive influence of Ca 2+ accumulation in mitochondria isolated following exhaustive exercise may be diminished as a result of training

  9. Effect of high-intensity intermittent swimming training on fatty acid oxidation enzyme activity in rat skeletal muscle.

    Science.gov (United States)

    Terada, Shin; Tabata, Izumi; Higuchi, Mitsuru

    2004-02-01

    We previously reported that high-intensity exercise training significantly increased citrate synthase (CS) activity, a marker of oxidative enzyme, in rat skeletal muscle to a level equaling that attained after low-intensity prolonged exercise training (Terada et al., J Appl Physiol 90: 2019-2024, 2001). Since mitochondrial oxidative enzymes and fatty acid oxidation (FAO) enzymes are often increased simultaneously, we assessed the effect of high-intensity intermittent swimming training on FAO enzyme activity in rat skeletal muscle. Male Sprague-Dawley rats (3 to 4 weeks old) were assigned to a 10-day period of high-intensity intermittent exercise training (HIT), low-intensity prolonged exercise training (LIT), or sedentary control conditions. In the HIT group, the rats repeated fourteen 20 s swimming sessions with a weight equivalent to 14-16% of their body weight. Between the exercise sessions, a 10 s pause was allowed. Rats in the LIT group swam 6 h/day in two 3 h sessions separated by 45 min of rest. CS activity in the triceps muscle of rats in the HIT and LIT groups was significantly higher than that in the control rats by 36 and 39%, respectively. Furthermore, 3-beta hydroxyacyl-CoA dehydrogenase (HAD) activity, an important enzyme in the FAO pathway in skeletal muscle, was higher in the two training groups than in the control rats (HIT: 100%, LIT: 88%). No significant difference in HAD activity was observed between the two training groups. In conclusion, the present investigation demonstrated that high-intensity intermittent swimming training elevated FAO enzyme activity in rat skeletal muscle to a level similar to that attained after 6 h of low-intensity prolonged swimming exercise training.

  10. Comparison of in vivo postexercise phosphocreatine recovery and resting ATP synthesis flux for the assessment of skeletal muscle mitochondrial function

    NARCIS (Netherlands)

    Broek, van den N.M.A.; Ciapaite, J.; Nicolay, K.; Prompers, J.J.

    2010-01-01

    31P magnetic resonance spectroscopy (MRS) has been used to assess skeletal muscle mitochondrial function in vivo by measuring 1) phosphocreatine (PCr) recovery after exercise or 2) resting ATP synthesis flux with saturation transfer (ST). In this study, we compared both parameters in a rat model of

  11. Skeletal muscle mitochondrial bioenergetics and morphology in high fat diet induced obesity and insulin resistance: focus on dietary fat source

    Directory of Open Access Journals (Sweden)

    Rosalba ePutti

    2016-01-01

    Full Text Available It has been suggested that skeletal muscle mitochondria play a key role in high fat diet induced insulin resistance. Two opposite views are debated on mechanisms by which mitochondrial function could be involved in skeletal muscle insulin resistance. In one theory, mitochondrial dysfunction is suggested to cause intramyocellular lipid accumulation leading to insulin resistance. In the second theory, excess fuel within mitochondria in the absence of increased energy demand stimulates mitochondrial oxidant production and emission, ultimately leading to the development of insulin resistance. Noteworthy, mitochondrial bioenergetics is strictly associated with the maintenance of normal mitochondrial morphology by maintaining the balance between the fusion and fission processes. A shift towards mitochondrial fission with reduction of fusion protein, mainly mitofusin 2, has been associated with reduced insulin sensitivity and inflammation in obesity and insulin resistance development. However, dietary fat source during chronic overfeeding differently affects mitochondrial morphology. Saturated fatty acids induce skeletal muscle insulin resistance and inflammation associated with fission phenotype, whereas ω-3 polyunsaturated fatty acids improve skeletal muscle insulin sensitivity and inflammation, associated with a shift toward mitochondrial fusion phenotype. The present minireview focuses on mitochondrial bioenergetics and morphology in skeletal muscle insulin resistance, with particular attention to the effect of different dietary fat sources on skeletal muscle mitochondria morphology and fusion/fission balance.

  12. (-)-Epicatechin administration and exercising skeletal muscle vascular control and microvascular oxygenation in healthy rats.

    Science.gov (United States)

    Copp, Steven W; Inagaki, Tadakatsu; White, Michael J; Hirai, Daniel M; Ferguson, Scott K; Holdsworth, Clark T; Sims, Gabrielle E; Poole, David C; Musch, Timothy I

    2013-01-15

    Consumption of the dietary flavanol (-)-epicatechin (EPI) is associated with enhanced endothelial function and augmented skeletal muscle capillarity and mitochondrial volume density. The potential for EPI to improve peripheral vascular function and muscle oxygenation during exercise is unknown. We tested the hypothesis that EPI administration in healthy rats would improve treadmill exercise performance secondary to elevated skeletal muscle blood flow and vascular conductance [VC, blood flow/mean arterial pressure (MAP)] and improved skeletal muscle microvascular oxygenation. Rats received water (control, n = 12) or 4 mg/kg EPI (n = 12) via oral gavage daily for 24 days. Exercise endurance capacity and peak O(2) uptake (Vo(2) peak) were measured via treadmill runs to exhaustion. MAP (arterial catheter) and blood flow (radiolabeled microspheres) were measured and VC was calculated during submaximal treadmill exercise (25 m/min, 5% grade). Spinotrapezius muscle microvascular O(2) pressure (Po(2mv)) was measured (phosphorescence quenching) during electrically induced twitch (1 Hz) contractions. In conscious rats, EPI administration resulted in lower (↓~5%) resting (P = 0.03) and exercising (P = 0.04) MAP. There were no differences in exercise endurance capacity, Vo(2) peak, total exercising hindlimb blood flow (control, 154 ± 13; and EPI, 159 ± 8 ml·min(-1)·100 g(-1), P = 0.68), or VC (control, 1.13 ± 0.10; and EPI, 1.24 ± 0.08 ml·min(-1)·100 g(-1)·mmHg(-1), P = 0.21) between groups. Following anesthesia, EPI resulted in lower MAP (↓~16%) but did not impact resting Po(2mv) or any kinetics parameters (P > 0.05 for all) during muscle contractions compared with control. EPI administration (4 mg·kg(-1)·day(-1)) improved modestly cardiovascular function (i.e., ↓MAP) with no impact on exercise performance, total exercising skeletal muscle blood flow and VC, or contracting muscle microvascular oxygenation in healthy rats.

  13. PGC-1α is dispensable for exercise-induced mitochondrial biogenesis in skeletal muscle.

    Directory of Open Access Journals (Sweden)

    Glenn C Rowe

    Full Text Available Exercise confers numerous health benefits, many of which are thought to stem from exercise-induced mitochondrial biogenesis (EIMB in skeletal muscle. The transcriptional coactivator PGC-1α, a potent regulator of metabolism in numerous tissues, is widely believed to be required for EIMB. We show here that this is not the case. Mice engineered to lack PGC-1α specifically in skeletal muscle (Myo-PGC-1αKO mice retained intact EIMB. The exercise capacity of these mice was comparable to littermate controls. Induction of metabolic genes after 2 weeks of in-cage voluntary wheel running was intact. Electron microscopy revealed no gross abnormalities in mitochondria, and the mitochondrial biogenic response to endurance exercise was as robust in Myo-PGC-1αKO mice as in wildtype mice. The induction of enzymatic activity of the electron transport chain by exercise was likewise unperturbed in Myo-PGC-1αKO mice. These data demonstrate that PGC-1α is dispensable for exercise-induced mitochondrial biogenesis in skeletal muscle, in sharp contrast to the prevalent assumption in the field.

  14. Protein and amino acid metabolism in skeletal muscle

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Guoyao.

    1989-01-01

    Isolated chick extensor digitorum communis (EDC) muscles and, in some experiments, rat skeletal muscles were used to study a number of aspects of protein and amino acid metabolism. (1) Chick EDC muscles synthesize and release large amounts of alanine and glutamine, which indirectly obtain their amino groups from branched-chain amino acids (BCAA). (2) Acetoacetate or DL-{beta}-hydroxybutyrate (4 mM) decrease (P < 0.01) alanine synthesis and BCAA transamination in EDC muscles from 24-h fasted chicks by decreasing (P < 0.01) intracellular concentrations of pyruvate due to inhibition of glycolysis. (3) Glutamine is extensively degraded in skeletal muscles from both chicks and rats, thus challenging the traditional view that glutamine oxidation is negligible in skeletal muscle. The cytosolic glutamine aminotransferases L and K in the rat and the mitochondrial phosphate-activated glutaminase in the chick play important roles in the conversion of glutamine to {alpha}-ketoglutarate for further oxidation. (4) Although methionine has been reported to be extensively transaminated in rat skeletal muscle preparations in the absence of other amino acids, transamination of methionine is absent or negligible in chick and rat skeletal muscles in the presence of physiological concentrations of amino acids. (5) Glutamine at 1.0-15 mM increases (P < 0.01) protein synthesis ({sup 3}H-phenylalanine incorporation), and at 10.0-15.0 mM decreases (P < 0.05) protein degradation ({sup 3}H-phenylalanine release from prelabelled protein in vivo) in EDC muscles from fed chicks as compared to muscles incubated in the absence of glutamine. (6) Acetoacetate or DL-{beta}-hydroxybutyrate (4 mM) has a small but significant inhibitory effect (P < 0.05) on the rate of protein synthesis, but has no effect (P > 0.05) on the rate of protein degradation in EDC muscles from fed chicks.

  15. Microbiopsies versus Bergström needle for skeletal muscle sampling: impact on maximal mitochondrial respiration rate.

    Science.gov (United States)

    Isner-Horobeti, M E; Charton, A; Daussin, F; Geny, B; Dufour, S P; Richard, R

    2014-05-01

    Microbiopsies are increasingly used as an alternative to the standard Bergström technique for skeletal muscle sampling. The potential impact of these two different procedures on mitochondrial respiration rate is unknown. The objective of this work was to compare microbiopsies versus Bergström procedure on mitochondrial respiration in skeletal muscle. 52 vastus lateralis muscle samples were obtained from 13 anesthetized pigs, either with a Bergström [6 gauges (G)] needle or with microbiopsy needles (12, 14, 18G). Maximal mitochondrial respiration (V GM-ADP) was assessed using an oxygraphic method on permeabilized fibers. The weight of the muscle samples and V GM-ADP decreased with the increasing gauge of the needles. A positive nonlinear relationship was observed between the weight of the muscle sample and the level of maximal mitochondrial respiration (r = 0.99, p respiration (r = 0.99, p respiration compared to the standard Bergström needle.Therefore, the higher the gauge (i.e. the smaller the size) of the microbiopsy needle, the lower is the maximal rate of respiration. Microbiopsies of skeletal muscle underestimate the maximal mitochondrial respiration rate, and this finding needs to be highlighted for adequate interpretation and comparison with literature data.

  16. Genetically Determined Insulin Resistance is Characterized by Down-Regulation of Mitochondrial Oxidative Metabolism in Human Skeletal Muscle

    DEFF Research Database (Denmark)

    Kristensen, Jonas M; Skov, Vibe; Wojtaszewski, Jørgen

    2010-01-01

    Transcriptional profiling of skeletal muscle from patients with type 2 diabetes and high-risk individuals have demonstrated a co-ordinated down-regulation of oxidative phosphorylation (OxPhos) genes, suggesting a link between insulin resistance and mitochondrial dysfunction. However, whether...... mitochondrial dysfunction is a cause or consequence of insulin resistance remains to be clarified. In the present study, we tested the hypothesis that mitochondrial oxidative metabolism was down-regulated in skeletal muscle of patients with genetically determined insulin resistance. Skeletal muscle biopsies.......02), and complex V (ATP5B; p=0.005). Our data demonstrate that genetically determined insulin resistance is associated with a co-ordinated down-regulation of OxPhos components both at the transcriptional and translational level. These findings suggest that an impaired biological response to insulin in skeletal...

  17. The role of mitochondrial DNA damage at skeletal muscle oxidative stress on the development of type 2 diabetes.

    Science.gov (United States)

    Dos Santos, Julia Matzenbacher; de Oliveira, Denise Silva; Moreli, Marcos Lazaro; Benite-Ribeiro, Sandra Aparecida

    2018-04-20

    Reduced cellular response to insulin in skeletal muscle is one of the major components of the development of type 2 diabetes (T2D). Mitochondrial dysfunction involves in the accumulation of toxic reactive oxygen species (ROS) that leads to insulin resistance. The aim of this study was to verify the involvement of mitochondrial DNA damage at ROS generation in skeletal muscle during development of T2D. Wistar rats were fed a diet containing 60% fat over 8 weeks and at day 14 a single injection of STZ (25 mg/kg) was administered (T2D-induced). Control rats received standard food and an injection of citrate buffer. Blood and soleus muscle were collected. Abdominal fat was quantified as well as glucose, triglyceride, LDL, HDL, and total cholesterol in plasma and mtDNA copy number, cytochrome b (cytb) mRNA, 8-hydroxyguanosine, and 8-isoprostane (a marker of ROS) in soleus muscle. T2D-induced animal presented similar characteristics to humans that develop T2D such as changes in blood glucose, abdominal fat, LDL, HDL and cholesterol total. In soleus muscle 8-isoprostane, mtDNA copy number and 8-hydroxyguanosine were increased, while cytb mRNA was decreased in T2D. Our results suggest that in the development of T2D, when risks factors of T2D are present, intracellular oxidative stress increases in skeletal muscle and is associated with a decrease in cytb transcription. To overcome this process mtDNA increased but due to the proximity of ROS generation, mtDNA remains damaged by oxidation leading to an increase in ROS in a vicious cycle accounting to the development of insulin resistance and further T2D.

  18. Skeletal muscle mitochondrial respiration in AMPKa2 kinase dead mice

    DEFF Research Database (Denmark)

    Larsen, Steen; Kristensen, Jonas Møller; Stride, Nis

    2012-01-01

    AIM: To study if the phenotypical characteristics (exercise intolerance; reduced spontaneous activity) of the AMPKa2 kinase-dead (KD) mice can be explained by a reduced mitochondrial respiratory flux rates (JO(2) ) in skeletal muscle. Secondly, the effect of the maturation process on JO(2...

  19. Alpha-adrenergic receptors in rat skeletal muscle

    DEFF Research Database (Denmark)

    Rattigan, S; Appleby, G J; Edwards, S J

    1986-01-01

    Sarcolemma-enriched preparations from muscles rich in slow oxidative red fibres contained specific binding sites for the alpha 1 antagonist, prazosin (e.g. soleus Kd 0.13 nM, Bmax 29 fmol/mg protein). Binding sites for prazosin were almost absent from white muscle. Displacement of prazosin bindin...... adrenergic receptors are present on the sarcolemma of slow oxidative red fibres of rat skeletal muscle. The presence provides the mechanistic basis for apparent alpha-adrenergic effects to increase glucose and oxygen uptake in perfused rat hindquarter....

  20. MicroRNA-761 regulates mitochondrial biogenesis in mouse skeletal muscle in response to exercise

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yanli [Affiliated Hospital of Hebei Engineering University, Handan, 056002, Hebei (China); Zhao, Chaoxian; Sun, Xuewen [Medical College of Hebei Engineering University, Handan, 056002, Hebei (China); Liu, Zhijun, E-mail: liuzhij1207@163.com [Affiliated Hospital of Hebei Engineering University, Handan, 056002, Hebei (China); Zhang, Jianzhong, E-mail: zhangjianzhong@icdc.cn [National Institute for Communicable Disease Control and Prevention (ICDC), Chinese Center for Disease Control and Prevention (China CDC), Beijing, 102206 (China)

    2015-11-06

    MicroRNAs (miRNAs) have been suggested to play critical roles in skeletal muscle in response to exercise. Previous study has shown that miR-761 was involved in a novel model regulating the mitochondrial network. However, its role in mitochondrial biogenesis remains poorly understood. Therefore, the current study was aimed to examine the effect of miR-761 on mitochondrial biogenesis in skeletal muscle. Real-time quantitative PCR analysis demonstrated that aberrantly expressed miR-761 is involved in exercise activity and miR-761 is decreased by exercise training compared with the sedentary control mice. miR-761 suppresses mitochondrial biogenesis of C{sub 2}C{sub 12} myocytes by targeting the 3′-UTR of peroxisome proliferator-activated receptor gamma (PPARγ) coactivator-1 (PGC-1α). Overexpression of miR-761 was capable of inhibiting the protein expression levels of PGC-1α. Moreover, miR-761 overexpression suppressed the p38 MAPK signaling pathway and down-regulated the expression of phosphorylated MAPK-activated protein kinase-2 (P-MK2), a downstream kinase of p38 MAPK. The phosphorylation of activating transcription factors 2 (ATF2) that plays a functional role in linking the activation of the p38 MAPK pathway to enhanced transcription of the PGC-1α was also inhibited by the overexpression of miR-761. These findings revealed a novel regulation mechanism for miR-761 in skeletal myocytes, and contributed to a better understanding of the modulation of skeletal muscle in response to exercise. - Highlights: • Endurance exercise decreases miR-761 expression in skeletal muscle. • MiR-761 suppresses mitochondrial biogenesis in C{sub 2}C{sub 12} myocytes. • MiR-761 directly targeted PGC-1α expression. • MiR-761 suppresses p38 MAPK signaling pathways in C{sub 2}C{sub 12} myocytes. • A novel mechanism for miR-761 in skeletal myocytes is demonstrated.

  1. Impaired skeletal muscle mitochondrial function in morbidly obese patients is normalized one year after bariatric surgery.

    Science.gov (United States)

    Vijgen, Guy H E J; Bouvy, Nicole D; Hoeks, Joris; Wijers, Sander; Schrauwen, Patrick; van Marken Lichtenbelt, Wouter D

    2013-01-01

    Obesity and type 2 diabetes are associated with impaired skeletal muscle mitochondrial metabolism. As an intrinsic characteristic of an individual, skeletal muscle mitochondrial dysfunction could be a risk factor for weight gain and obesity-associated co-morbidities, such as type 2 diabetes. On the other hand, impaired skeletal muscle metabolism could be a consequence of obesity. We hypothesize that marked weight loss after bariatric surgery recovers skeletal muscle mitochondrial function. Skeletal muscle mitochondrial function as assessed by high-resolution respirometry was measured in 8 morbidly obese patients (body mass index [BMI], 41.3±4.7 kg/m(2); body fat, 48.3%±5.2%) before and 1 year after bariatric surgery (mean weight loss: 35.0±8.6 kg). The results were compared with a lean (BMI 22.8±1.1 kg/m(2); body fat, 15.6%±4.7%) and obese (BMI 33.5±4.2 kg/m(2); body fat, 34.1%±6.3%) control group. Before surgery, adenosine diphosphate (ADP)-stimulated (state 3) respiration on glutamate/succinate was decreased compared with lean patients (9.5±2.4 versus 15.6±4.4 O2 flux/mtDNA; Psurgery, mitochondrial function was comparable to that of lean controls (after weight loss, 12.3±5.5; lean, 15.6±4.4 O2 flux/mtDNA). In addition, we observed an increased state 3 respiration on a lipid substrate after weight loss (10.0±3.2 versus 14.0±6.6 O2 flux/mtDNA; Pweight loss. Copyright © 2013 American Society for Bariatric Surgery. Published by Elsevier Inc. All rights reserved.

  2. The relationship between skeletal muscle mitochondrial citrate synthase activity and whole body oxygen uptake adaptations in response to exercise training

    DEFF Research Database (Denmark)

    Vigelsø Hansen, Andreas; Andersen, Nynne Bjerre; Dela, Flemming

    2014-01-01

    Citrate synthase (CS) activity is a validated biomarker for mitochondrial density in skeletal muscle. CS activity is also used as a biochemical marker of the skeletal muscle oxidative adaptation to a training intervention, and a relationship between changes in whole body aerobic capacity and chan......Citrate synthase (CS) activity is a validated biomarker for mitochondrial density in skeletal muscle. CS activity is also used as a biochemical marker of the skeletal muscle oxidative adaptation to a training intervention, and a relationship between changes in whole body aerobic capacity...

  3. The measurement of reversible redox dependent post-translational modifications and their regulation of mitochondrial and skeletal muscle function

    Directory of Open Access Journals (Sweden)

    Philip A Kramer

    2015-11-01

    Full Text Available Mitochondrial oxidative stress is a common feature of skeletal myopathies across multiple conditions; however, the mechanism by which it contributes to skeletal muscle dysfunction remains controversial. Oxidative damage to proteins, lipids, and DNA has received the most attention, yet an important role for reversible redox post-translational modifications (PTMs in pathophysiology is emerging. The possibility that these PTMs can exert dynamic control of muscle function implicates them as a mechanism contributing to skeletal muscle dysfunction in chronic disease. Herein, we discuss the significance of thiol-based redox dependent modifications to mitochondrial, myofibrillar and excitation-contraction (EC coupling proteins with an emphasis on how these changes could alter skeletal muscle performance under chronically stressed conditions. A major barrier to a better mechanistic understanding of the role of reversible redox PTMs in muscle function is the technical challenges associated with accurately measuring the changes of site-specific redox PTMs. Here we will critically review current approaches with an emphasis on sample preparation artifacts, quantitation, and specificity. Despite these challenges, the ability to accurately quantify reversible redox PTMs is critical to understanding the mechanisms by which mitochondrial oxidative stress contributes to skeletal muscle dysfunction in chronic diseases.

  4. The Measurement of Reversible Redox Dependent Post-translational Modifications and Their Regulation of Mitochondrial and Skeletal Muscle Function

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, Philip A.; Duan, Jicheng; Qian, Wei-Jun; Marcinek, David J.

    2015-11-25

    Mitochondrial oxidative stress is a common feature of skeletal myopathies across multiple conditions; however, the mechanism by which it contributes to skeletal muscle dysfunction remains controversial. Oxidative damage to proteins, lipids, and DNA has received the most attention, yet an important role for reversible redox post-translational modifications (PTMs) in pathophysiology is emerging. The possibility that these PTMs can exert dynamic control of muscle function implicates them as a mechanism contributing to skeletal muscle dysfunction in chronic disease. Herein, we discuss the significance of thiol-based redox dependent modifications to mitochondrial, myofibrillar and excitation-contraction (EC) coupling proteins with an emphasis on how these changes could alter skeletal muscle performance under chronically stressed conditions. A major barrier to a better mechanistic understanding of the role of reversible redox PTMs in muscle function is the technical challenges associated with accurately measuring the changes of site-specific redox PTMs. Here we will critically review current approaches with an emphasis on sample preparation artifacts, quantitation, and specificity. Despite these challenges, the ability to accurately quantify reversible redox PTMs is critical to understanding the mechanisms by which mitochondrial oxidative stress contributes to skeletal muscle dysfunction in chronic diseases.

  5. Radiation injury to skeletal muscle

    International Nuclear Information System (INIS)

    Persons, C.C.M.; Wondergem, J.; Leer, J.W.H.

    1997-01-01

    Radiotherapy of neoplasia has increased the mean life expectancy of cancer patients. On the other hand, more reports are published on morbidity of the treatment with regard to normal tissue. Studies on skeletal muscle injury specifically are scarce, but many clinical long term follow-up studies make note of side effects as muscle atrophy, fibrosis and limited function. Furthermore it is suggested that skeletal muscles of children are more prone to radiation injury than those of adult subjects. Effects of radiation on skeletal muscle were studied in rats. On hind limb of young (100 g) and adult (350 g) rats was irradiated with single doses (15-30 Gy), while the other served as control. Follow-up was up to 12 months post treatment. Muscular function in young rats was decreased significantly at 6 months post irradiation, but did not further decrease in the following 6 months. The amount of collagen, on the other hand, was not increased at 6 months, but became highly elevated at 12 months past treatment. This suggests that at 6 months, impaired muscular function may not be explained by increased fibrotic tissues. This is an agreement with results obtained in adult rats, where function was also impaired, without concomitant increase in collagen. In an earlier study, mitochondrial oxygen consumption was dose dependently decreased after irradiation, at 12 months, but not at 6 months post treatment. Furthermore, myosin-actin interaction was measured in skinned fibers. The first results of this study indicate changes in the interaction of contraction proteins, as early as 6 months post treatment. (authors)

  6. Physical exercise in aging human skeletal muscle increases mitochondrial calcium uniporter expression levels and affects mitochondria dynamics.

    Science.gov (United States)

    Zampieri, Sandra; Mammucari, Cristina; Romanello, Vanina; Barberi, Laura; Pietrangelo, Laura; Fusella, Aurora; Mosole, Simone; Gherardi, Gaia; Höfer, Christian; Löfler, Stefan; Sarabon, Nejc; Cvecka, Jan; Krenn, Matthias; Carraro, Ugo; Kern, Helmut; Protasi, Feliciano; Musarò, Antonio; Sandri, Marco; Rizzuto, Rosario

    2016-12-01

    Age-related sarcopenia is characterized by a progressive loss of muscle mass with decline in specific force, having dramatic consequences on mobility and quality of life in seniors. The etiology of sarcopenia is multifactorial and underlying mechanisms are currently not fully elucidated. Physical exercise is known to have beneficial effects on muscle trophism and force production. Alterations of mitochondrial Ca 2+ homeostasis regulated by mitochondrial calcium uniporter (MCU) have been recently shown to affect muscle trophism in vivo in mice. To understand the relevance of MCU-dependent mitochondrial Ca 2+ uptake in aging and to investigate the effect of physical exercise on MCU expression and mitochondria dynamics, we analyzed skeletal muscle biopsies from 70-year-old subjects 9 weeks trained with either neuromuscular electrical stimulation (ES) or leg press. Here, we demonstrate that improved muscle function and structure induced by both trainings are linked to increased protein levels of MCU Ultrastructural analyses by electron microscopy showed remodeling of mitochondrial apparatus in ES-trained muscles that is consistent with an adaptation to physical exercise, a response likely mediated by an increased expression of mitochondrial fusion protein OPA1. Altogether these results indicate that the ES-dependent physiological effects on skeletal muscle size and force are associated with changes in mitochondrial-related proteins involved in Ca 2+ homeostasis and mitochondrial shape. These original findings in aging human skeletal muscle confirm the data obtained in mice and propose MCU and mitochondria-related proteins as potential pharmacological targets to counteract age-related muscle loss. © 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  7. Responses of skeletal muscle lipid metabolism in rat gastrocnemius to hypothyroidism and iodothyronine administration: a putative role for FAT/CD36.

    Science.gov (United States)

    Lombardi, Assunta; De Matteis, Rita; Moreno, Maria; Napolitano, Laura; Busiello, Rosa Anna; Senese, Rosalba; de Lange, Pieter; Lanni, Antonia; Goglia, Fernando

    2012-11-15

    Iodothyronines such as triiodothyronine (T(3)) and 3,5-diiodothyronine (T(2)) influence energy expenditure and lipid metabolism. Skeletal muscle contributes significantly to energy homeostasis, and the above iodothyronines are known to act on this tissue. However, little is known about the cellular/molecular events underlying the effects of T(3) and T(2) on skeletal muscle lipid handling. Since FAT/CD36 is involved in the utilization of free fatty acids by skeletal muscle, specifically in their import into that tissue and presumably their oxidation at the mitochondrial level, we hypothesized that related changes in lipid handling and in FAT/CD36 expression and subcellular redistribution would occur due to hypothyroidism and to T(3) or T(2) administration to hypothyroid rats. In gastrocnemius muscles isolated from hypothyroid rats, FAT/CD36 was upregulated (mRNA levels and total tissue, sarcolemmal, and mitochondrial protein levels). Administration of either T(3) or T(2) to hypothyroid rats resulted in 1) little or no change in FAT/CD36 mRNA level, 2) a decreased total FAT/CD36 protein level, and 3) further increases in FAT/CD36 protein level in sarcolemma and mitochondria. Thus, the main effect of each iodothyronine seemed to be exerted at the level of FAT/CD36 cellular distribution. The effect of further increases in FAT/CD36 protein level in sarcolemma and mitochondria was already evident at 1 h after iodothyronine administration. Each iodothyronine increased the mitochondrial fatty acid oxidation rate. However, the mechanisms underlying their rapid effects seem to differ; T(2) and T(3) each induce FAT/CD36 translocation to mitochondria, but only T(2) induces increases in carnitine palmitoyl transferase system activity and in the mitochondrial substrate oxidation rate.

  8. Skeletal muscle proteomic signature and metabolic impairment in pulmonary hypertension.

    Science.gov (United States)

    Malenfant, Simon; Potus, François; Fournier, Frédéric; Breuils-Bonnet, Sandra; Pflieger, Aude; Bourassa, Sylvie; Tremblay, Ève; Nehmé, Benjamin; Droit, Arnaud; Bonnet, Sébastien; Provencher, Steeve

    2015-05-01

    Exercise limitation comes from a close interaction between cardiovascular and skeletal muscle impairments. To better understand the implication of possible peripheral oxidative metabolism dysfunction, we studied the proteomic signature of skeletal muscle in pulmonary arterial hypertension (PAH). Eight idiopathic PAH patients and eight matched healthy sedentary subjects were evaluated for exercise capacity, skeletal muscle proteomic profile, metabolism, and mitochondrial function. Skeletal muscle proteins were extracted, and fractioned peptides were tagged using an iTRAQ protocol. Proteomic analyses have documented a total of 9 downregulated proteins in PAH skeletal muscles and 10 upregulated proteins compared to healthy subjects. Most of the downregulated proteins were related to mitochondrial structure and function. Focusing on skeletal muscle metabolism and mitochondrial health, PAH patients presented a decreased expression of oxidative enzymes (pyruvate dehydrogenase, p metabolism in PAH skeletal muscles. We provide evidences that impaired mitochondrial and metabolic functions found in the lungs and the right ventricle are also present in skeletal muscles of patients. • Proteomic and metabolic analysis show abnormal oxidative metabolism in PAH skeletal muscle. • EM of PAH patients reveals abnormal mitochondrial structure and distribution. • Abnormal mitochondrial health and function contribute to exercise impairments of PAH. • PAH may be considered a vascular affliction of heart and lungs with major impact on peripheral muscles.

  9. The effect of high-intensity training on mitochondrial fat oxidation in skeletal muscle and subcutaneous adipose tissue

    DEFF Research Database (Denmark)

    Larsen, Steen; Danielsen, J H; Søndergård, Stine Dam

    2015-01-01

    High-intensity interval training (HIT) is known to increase mitochondrial content in a similar way as endurance training [60-90% of maximal oxygen uptake (VO2peak )]. Whether HIT increases the mitochondria's ability to oxidize lipids is currently debated. We investigated the effect of HIT...... of HIT (three times per week at 298 ± 21 W). HIT significantly increased VO2peak from 2.9 ± 0.2 to 3.1 ± 0.2 L/min. No differences were seen in maximal fat oxidation in either skeletal muscle or adipose tissue. Km (app) for octanoyl carnitine or palmitoyl carnitine were similar after training in skeletal...... muscle and adipose tissue. Maximal OXPHOS capacity with complex I- and II-linked substrates was increased after training in skeletal muscle but not in adipose tissue. In conclusion, 6 weeks of HIT increased VO2peak . Mitochondrial content and mitochondrial OXPHOS capacity were increased in skeletal...

  10. Age-Associated Impairments in Mitochondrial ADP Sensitivity Contribute to Redox Stress in Senescent Human Skeletal Muscle

    Directory of Open Access Journals (Sweden)

    Graham P. Holloway

    2018-03-01

    Full Text Available Summary: It remains unknown if mitochondrial bioenergetics are altered with aging in humans. We established an in vitro method to simultaneously determine mitochondrial respiration and H2O2 emission in skeletal muscle tissue across a range of biologically relevant ADP concentrations. Using this approach, we provide evidence that, although the capacity for mitochondrial H2O2 emission is not increased with aging, mitochondrial ADP sensitivity is impaired. This resulted in an increase in mitochondrial H2O2 and the fraction of electron leak to H2O2, in the presence of virtually all ADP concentrations examined. Moreover, although prolonged resistance training in older individuals increased muscle mass, strength, and maximal mitochondrial respiration, exercise training did not alter H2O2 emission rates in the presence of ADP, the fraction of electron leak to H2O2, or the redox state of the muscle. These data establish that a reduction in mitochondrial ADP sensitivity increases mitochondrial H2O2 emission and contributes to age-associated redox stress. : Holloway et al. show that an inability of ADP to decrease mitochondrial reactive oxygen species emission contributes to redox stress in skeletal muscle tissue of older individuals and that this process is not recovered following prolonged resistance-type exercise training, despite the general benefits of resistance training for muscle health. Keywords: mitochondria, aging, muscle, ROS, H2O2, ADP, respiration, bioenergetics, exercise, resistance training

  11. Exercise Promotes Healthy Aging of Skeletal Muscle.

    Science.gov (United States)

    Cartee, Gregory D; Hepple, Russell T; Bamman, Marcas M; Zierath, Juleen R

    2016-06-14

    Primary aging is the progressive and inevitable process of bodily deterioration during adulthood. In skeletal muscle, primary aging causes defective mitochondrial energetics and reduced muscle mass. Secondary aging refers to additional deleterious structural and functional age-related changes caused by diseases and lifestyle factors. Secondary aging can exacerbate deficits in mitochondrial function and muscle mass, concomitant with the development of skeletal muscle insulin resistance. Exercise opposes deleterious effects of secondary aging by preventing the decline in mitochondrial respiration, mitigating aging-related loss of muscle mass and enhancing insulin sensitivity. This review focuses on mechanisms by which exercise promotes "healthy aging" by inducing modifications in skeletal muscle. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Passive stiffness of rat skeletal muscle undernourished during fetal development

    Directory of Open Access Journals (Sweden)

    Ana Elisa Toscano

    2010-01-01

    Full Text Available OBJECTIVES: The aim of the study was to investigate the effect of fetal undernutrition on the passive mechanical properties of skeletal muscle of weaned and young adult rats. INTRODUCTION: A poor nutrition supply during fetal development affects physiological functions of the fetus. From a mechanical point of view, skeletal muscle can be also characterized by its resistance to passive stretch. METHODS: Male Wistar rats were divided into two groups according to their mother's diet during pregnancy: a control group (mothers fed a 17% protein diet and an isocaloric low-protein group (mothers fed a 7.8% protein diet. At birth, all mothers received a standardized meal ad libitum. At the age of 25 and 90 days, the soleus muscle and extensor digitorum longus (EDL muscles were removed in order to test the passive mechanical properties. A first mechanical test consisted of an incremental stepwise extension test using fast velocity stretching (500 mm/s enabling us to measure, for each extension stepwise, the dynamic stress (σd and the steady stress (σs. A second test consisted of a slow velocity stretch in order to calculate normalized stiffness and tangent modulus from the stress-strain relationship. RESULTS: The results for the mechanical properties showed an important increase in passive stiffness in both the soleus and EDL muscles in weaned rat. In contrast, no modification was observed in young adult rats. CONCLUSIONS: The increase in passive stiffness in skeletal muscle of weaned rat submitted to intrauterine undernutrition it is most likely due to changes in muscle passive stiffness.

  13. Ulk1-mediated autophagy plays an essential role in mitochondrial remodeling and functional regeneration of skeletal muscle.

    Science.gov (United States)

    Call, Jarrod A; Wilson, Rebecca J; Laker, Rhianna C; Zhang, Mei; Kundu, Mondira; Yan, Zhen

    2017-06-01

    Autophagy is a conserved cellular process for degrading aggregate proteins and dysfunctional organelle. It is still debatable if autophagy and mitophagy (a specific process of autophagy of mitochondria) play important roles in myogenic differentiation and functional regeneration of skeletal muscle. We tested the hypothesis that autophagy is critical for functional regeneration of skeletal muscle. We first observed time-dependent increases (3- to 6-fold) of autophagy-related proteins (Atgs), including Ulk1, Beclin1, and LC3, along with reduced p62 expression during C2C12 differentiation, suggesting increased autophagy capacity and flux during myogenic differentiation. We then used cardiotoxin (Ctx) or ischemia-reperfusion (I/R) to induce muscle injury and regeneration and observed increases in Atgs between days 2 and 7 in adult skeletal muscle followed by increased autophagy flux after day 7 Since Ulk1 has been shown to be essential for mitophagy, we asked if Ulk1 is critical for functional regeneration in skeletal muscle. We subjected skeletal muscle-specific Ulk1 knockout mice (MKO) to Ctx or I/R. MKO mice had significantly impaired recovery of muscle strength and mitochondrial protein content post-Ctx or I/R. Imaging analysis showed that MKO mice have significantly attenuated recovery of mitochondrial network at 7 and 14 days post-Ctx. These findings suggest that increased autophagy protein and flux occur during muscle regeneration and Ulk1-mediated mitophagy is critical for recovery for the mitochondrial network and hence functional regeneration. Copyright © 2017 the American Physiological Society.

  14. The high aerobic capacity of a small, marsupial rat-kangaroo (Bettongia penicillata) is matched by the mitochondrial and capillary morphology of its skeletal muscles.

    Science.gov (United States)

    Webster, Koa N; Dawson, Terence J

    2012-09-15

    We examined the structure-function relationships that underlie the aerobic capacities of marsupial mammals that hop. Marsupials have relatively low basal metabolic rates (BMR) and historically were seen as 'low energy' mammals. However, the red kangaroo, Macropus rufus (family Macropodidae), has aerobic capacities equivalent to athletic placentals. It has an extreme aerobic scope (fAS) and its large locomotor muscles feature high mitochondrial and capillary volumes. M. rufus belongs to a modern group of kangaroos and its high fAS is not general for marsupials. However, other hopping marsupials may have elevated aerobic capacities. Bettongia penicillata, a rat-kangaroo (family Potoroidae), is a small (1 kg), active hopper whose fAS is somewhat elevated. We examined the oxygen delivery system in its muscles to ascertain links with hopping. An elevated fAS of 23 provided a relatively high maximal aerobic oxygen consumption ( ) in B. penicillata; associated with this is a skeletal muscle mass of 44% of body mass. Ten muscles were sampled to estimate the total mitochondrial and capillary volume of the locomotor muscles. Values in B. penicillata were similar to those in M. rufus and in athletic placentals. This small hopper had high muscle mitochondrial volume densities (7.1-11.9%) and both a large total capillary volume (6 ml kg(-1) body mass) and total capillary erythrocyte volume (3.2 ml kg(-1)). Apparently, a considerable aerobic capacity is required to achieve the benefits of the extended stride in fast hopping. Of note, the ratio of to total muscle mitochondrial volume in B. penicillata was 4.9 ml O(2) min(-1) ml(-1). Similar values occur in M. rufus and also placental mammals generally, not only athletic species. If such relationships occur in other marsupials, a fundamental structure-function relationship for oxygen delivery to muscles likely originated with or before the earliest mammals.

  15. Temperature controls oxidative phosphorylation and reactive oxygen species production through uncoupling in rat skeletal muscle mitochondria.

    Science.gov (United States)

    Jarmuszkiewicz, Wieslawa; Woyda-Ploszczyca, Andrzej; Koziel, Agnieszka; Majerczak, Joanna; Zoladz, Jerzy A

    2015-06-01

    Mitochondrial respiratory and phosphorylation activities, mitochondrial uncoupling, and hydrogen peroxide formation were studied in isolated rat skeletal muscle mitochondria during experimentally induced hypothermia (25 °C) and hyperthermia (42 °C) compared to the physiological temperature of resting muscle (35 °C). For nonphosphorylating mitochondria, increasing the temperature from 25 to 42 °C led to a decrease in membrane potential, hydrogen peroxide production, and quinone reduction levels. For phosphorylating mitochondria, no temperature-dependent changes in these mitochondrial functions were observed. However, the efficiency of oxidative phosphorylation decreased, whereas the oxidation and phosphorylation rates and oxidative capacities of the mitochondria increased, with increasing assay temperature. An increase in proton leak, including uncoupling protein-mediated proton leak, was observed with increasing assay temperature, which could explain the reduced oxidative phosphorylation efficiency and reactive oxygen species production. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Metabolic characteristics of skeletal muscle from lean and obese Zucker rats

    International Nuclear Information System (INIS)

    Campion, D.R.; Shapira, J.F.; Allen, C.E.; Hausman, G.J.; Martin, R.J.

    1987-01-01

    The purpose of this study was to determine if the metabolic response to obesity and to pair feeding of obese Zucker rats to lean Zucker rats was similar across skeletal muscles. Oxidation of glucose, palmitate and isoleucine was studied in muscle strips in vitro using appropriate 14- carbon substrates as tracers. The plantaris muscle was subjected to histochemical analyses using an alkaline actomyosin ATPase, NADH-tetrazolium reductase and an oil red 0 stain. Soleus muscles from both ad libitum and pair fed obese rats oxidized less glucose to CO 2 , but released similar amounts of lactate when compared to the soleus muscles of lean rats. Oxidation of glucose was similar in the extensor digitorum longus (EDL) muscle of ad libitum fed obese rats, but lower when pair fed to the intake of lean rats. No differences were apparent in palmitate oxidation to CO 2 or in incorporation into lipid, except in the EDL muscle of pair-fed obese rats which exhibited a higher rate for palmitate metabolism when compared with lean rats. Isoleucine oxidation to CO 2 was higher in the EDL and plantaris muscles, but similar in the soleus muscle of ad libitum-fed obese rats when compared with lean rats. The magnitude of the difference in isoleucine oxidation was similar when the obese rats were pair fed. No differences in the percentage of plantaris muscle fibers sensitive to alkaline ATPase staining were observed. The plantaris muscle of obese rats, contained a higher proportion of oxidative fibers. These results indicate the great risk in generalizing about metabolic activity of the whole skeletal muscle mass based on observations made on one, or even two, distinct muscles in this animal model. Also, pair feeding of obese to lean Zucker rats did not result in uniform change sin metabolism between muscles of the obese rats

  17. Intact initiation of autophagy and mitochondrial fission by acute exercise in skeletal muscle of patientswith type 2 diabetes

    DEFF Research Database (Denmark)

    Kruse Sørensen, Rikke; Pedersen, Andreas James Thestrup; Kristensen, Jonas Møller

    2017-01-01

    AIMS: Type 2 diabetes (T2D) is characterized by insulin resistance, mitochondrial dysregulation, and, in some studies, exercise resistance in skeletal muscle. Regulation of autophagy and mitochondrial dynamics during exercise and recovery is important for skeletal muscle homeostasis......, and these responses may be altered in T2D. MATERIALS AND METHODS: We examined the effect of acute exercise on markers of autophagy and mitochondrial fusion and fission in skeletal muscle biopsies from patients with T2D (n=13) and weight-matched controls (n=14) before, immediately after and 3h after an acute bout...... of exercise. RESULTS: While mRNA levels of most markers of autophagy ( PIK3C, MAP1LC3B, SQSTM1, BNIP3, BNIP3L ) and mitochondrial dynamics ( OPA1, FIS1 ) remained unchanged, some either increased during and after exercise (GABARAPL1 ), decreased in the recovery period ( BECN1, ATG7, DNM1L ), or both ( MFN2...

  18. Exhaustive Training Increases Uncoupling Protein 2 Expression and Decreases Bcl-2/Bax Ratio in Rat Skeletal Muscle

    Directory of Open Access Journals (Sweden)

    W. Y. Liu

    2013-01-01

    Full Text Available This work investigates the effects of oxidative stress due to exhaustive training on uncoupling protein 2 (UCP2 and Bcl-2/Bax in rat skeletal muscles. A total of 18 Sprague-Dawley female rats were randomly divided into three groups: the control group (CON, the trained control group (TC, and the exhaustive trained group (ET. Malondialdehyde (MDA, superoxide dismutase (SOD, xanthine oxidase (XOD, ATPase, UCP2, and Bcl-2/Bax ratio in red gastrocnemius muscles were measured. Exhaustive training induced ROS increase in red gastrocnemius muscles, which led to a decrease in the cell antiapoptotic ability (Bcl-2/Bax ratio. An increase in UCP2 expression can reduce ROS production and affect mitochondrial energy production. Thus, oxidative stress plays a significant role in overtraining.

  19. Fast-twitch glycolytic skeletal muscle is predisposed to age-induced impairments in mitochondrial function

    DEFF Research Database (Denmark)

    Jacobs, Robert A; Díaz, Víctor; Soldini, Lavinia

    2013-01-01

    The etiology of mammalian senescence is suggested to involve the progressive impairment of mitochondrial function; however, direct observations of age-induced alterations in actual respiratory chain function are lacking. Accordingly, we assessed mitochondrial function via high-resolution respirom......The etiology of mammalian senescence is suggested to involve the progressive impairment of mitochondrial function; however, direct observations of age-induced alterations in actual respiratory chain function are lacking. Accordingly, we assessed mitochondrial function via high......-resolution respirometry and mitochondrial protein expression in soleus, quadricep, and lateral gastrocnemius skeletal muscles, which represent type 1 slow-twitch oxidative muscle (soleus) and type 2 fast-twitch glycolytic muscle (quadricep and gastrocnemius), respectively, in young (10-12 weeks) and mature (74-76 weeks......) mice. Electron transport through mitochondrial complexes I and III increases with age in quadricep and gastrocnemius, which is not observed in soleus. Mitochondrial coupling efficiency during respiration through complex I also deteriorates with age in gastrocnemius and shows a tendency (p = .085...

  20. Branched-chain amino acid-rich diet improves skeletal muscle wasting caused by cigarette smoke in rats.

    Science.gov (United States)

    Tomoda, Koichi; Kubo, Kaoru; Hino, Kazuo; Kondoh, Yasunori; Nishii, Yasue; Koyama, Noriko; Yamamoto, Yoshifumi; Yoshikawa, Masanori; Kimura, Hiroshi

    2014-04-01

    Cigarette smoke induces skeletal muscle wasting by a mechanism not yet fully elucidated. Branched-chain amino acids (BCAA) in the skeletal muscles are useful energy sources during exercise or systemic stresses. We investigated the relationship between skeletal muscle wasting caused by cigarette smoke and changes in BCAA levels in the plasma and skeletal muscles of rats. Furthermore, the effects of BCAA-rich diet on muscle wasting caused by cigarette smoke were also investigated. Wistar Kyoto (WKY) rats that were fed with a control or a BCAA-rich diet were exposed to cigarette smoke for four weeks. After the exposure, the skeletal muscle weight and BCAA levels in plasma and the skeletal muscles were measured. Cigarette smoke significantly decreased the skeletal muscle weight and BCAA levels in both plasma and skeletal muscles, while a BCAA-rich diet increased the skeletal muscle weight and BCAA levels in both plasma and skeletal muscles that had decreased by cigarette smoke exposure. In conclusion, skeletal muscle wasting caused by cigarette smoke was related to the decrease of BCAA levels in the skeletal muscles, while a BCAA-rich diet may improve cases of cigarette smoke-induced skeletal muscle wasting.

  1. Exercise Promotes Healthy Aging of Skeletal Muscle

    DEFF Research Database (Denmark)

    Cartee, Gregory D; Hepple, Russell T; Bamman, Marcas M

    2016-01-01

    caused by diseases and lifestyle factors. Secondary aging can exacerbate deficits in mitochondrial function and muscle mass, concomitant with the development of skeletal muscle insulin resistance. Exercise opposes deleterious effects of secondary aging by preventing the decline in mitochondrial...... respiration, mitigating aging-related loss of muscle mass and enhancing insulin sensitivity. This review focuses on mechanisms by which exercise promotes "healthy aging" by inducing modifications in skeletal muscle....

  2. Ginseng administration protects skeletal muscle from oxidative stress induced by acute exercise in rats.

    Science.gov (United States)

    Voces, J; Cabral de Oliveira, A C; Prieto, J G; Vila, L; Perez, A C; Duarte, I D G; Alvarez, A I

    2004-12-01

    Enzymatic activity was analyzed in the soleus, gastrocnemius (red and white) and plantaris muscles of acutely exercised rats after long-term administration of Panax ginseng extract in order to evaluate the protective role of ginseng against skeletal muscle oxidation. Ginseng extract (3, 10, 100, or 500 mg/kg) was administered orally for three months to male Wistar rats weighing 200 +/- 50 g before exercise and to non-exercised rats (N = 8/group). The results showed a membrane stabilizing capacity of the extract since mitochondrial function measured on the basis of citrate synthase and 3-hydroxyacyl-CoA dehydrogenase activities was reduced, on average, by 20% (P < 0.05) after exercise but the activities remained unchanged in animals treated with a ginseng dose of 100 mg/kg. Glutathione status did not show significant changes after exercise or treatment. Lipid peroxidation, measured on the basis of malondialdehyde levels, was significantly higher in all muscles after exercise, and again was reduced by about 74% (P < 0.05) by the use of ginseng extract. The administration of ginseng extract was able to protect muscle from exercise-induced oxidative stress irrespective of fiber type.

  3. Ginseng administration protects skeletal muscle from oxidative stress induced by acute exercise in rats

    Directory of Open Access Journals (Sweden)

    J. Voces

    2004-12-01

    Full Text Available Enzymatic activity was analyzed in the soleus, gastrocnemius (red and white and plantaris muscles of acutely exercised rats after long-term administration of Panax ginseng extract in order to evaluate the protective role of ginseng against skeletal muscle oxidation. Ginseng extract (3, 10, 100, or 500 mg/kg was administered orally for three months to male Wistar rats weighing 200 ± 50 g before exercise and to non-exercised rats (N = 8/group. The results showed a membrane stabilizing capacity of the extract since mitochondrial function measured on the basis of citrate synthase and 3-hydroxyacyl-CoA dehydrogenase activities was reduced, on average, by 20% (P < 0.05 after exercise but the activities remained unchanged in animals treated with a ginseng dose of 100 mg/kg. Glutathione status did not show significant changes after exercise or treatment. Lipid peroxidation, measured on the basis of malondialdehyde levels, was significantly higher in all muscles after exercise, and again was reduced by about 74% (P < 0.05 by the use of ginseng extract. The administration of ginseng extract was able to protect muscle from exercise-induced oxidative stress irrespective of fiber type.

  4. Postirradiation recovery of the skeletal muscle of rats of various age

    International Nuclear Information System (INIS)

    Popova, M.F.; Bulyakova, N.V.

    1977-01-01

    The skeletal muscle of young rats (particularly of 3-and 4-week old ones) exposed to local irradiation of 2000 R was markedly repaired in the course of one month after irradiation . This was indicated by a restored ability of the muscle for posttraumatic regeneration. A regeneration ability of the irradiated muscle of old rats was not restored. The more intensive processes of postirradiation recovery in muscles of young rats may be explained by their more active metabolism

  5. Age affects the contraction-induced mitochondrial redox response in skeletal muscle

    Directory of Open Access Journals (Sweden)

    Dennis R Claflin

    2015-02-01

    Full Text Available Compromised mitochondrial respiratory function is associated with advancing age. Damage due to an increase in reactive oxygen species (ROS with age is thought to contribute to the mitochondrial deficits. The coenzyme nicotinamide adenine dinucleotide in its reduced (NADH and oxidized (NAD+ forms plays an essential role in the cyclic sequence of reactions that result in the regeneration of ATP by oxidative phosphorylation in mitochondria. Monitoring mitochondrial NADH/NAD+ redox status during recovery from an episode of high energy demand thus allows assessment of mitochondrial function. NADH fluoresces when excited with ultraviolet light in the UV-A band and NAD+ does not, allowing NADH/NAD+ to be monitored in real time using fluorescence microscopy. Our goal was to assess mitochondrial function by monitoring the NADH fluorescence response following a brief period of high energy demand in muscle from adult and old wild-type (WT mice. This was accomplished by isolating whole lumbrical muscles from the hind paws of 7- and 28-month-old WT mice and making simultaneous measurements of force and NADH fluorescence responses during and after a 5 s maximum isometric contraction. All muscles exhibited fluorescence oscillations that were qualitatively similar and consisted of a brief transient increase followed by a longer transient period of reduced fluorescence and, finally, an increase that included an overshoot before recovering to resting level. Compared with the adult WT mice, muscles from the 28 mo WT mice exhibited a delayed peak during the first fluorescence transient and an attenuated recovery following the second transient. These findings indicate an impaired mitochondrial capacity to maintain NADH/NAD+ redox homeostasis during contractile activity in skeletal muscles of old mice.

  6. Skeletal Muscle Sorbitol Levels in Diabetic Rats with and without Insulin Therapy and Endurance Exercise Training

    Science.gov (United States)

    Sánchez, O. A.; Walseth, T. F.; Snow, L. M.; Serfass, R. C.; Thompson, L. V.

    2009-01-01

    Sorbitol accumulation is postulated to play a role in skeletal muscle dysfunction associated with diabetes. The purpose of this study was to determine the effects of insulin and of endurance exercise on skeletal muscle sorbitol levels in streptozotocin-induced diabetic rats. Rats were assigned to one experimental group (control sedentary, control exercise, diabetic sedentary, diabetic exercise, diabetic sedentary no-insulin). Diabetic rats received daily subcutaneous insulin. The exercise-trained rats ran on a treadmill (1 hour, 5X/wk, for 12 weeks). Skeletal muscle sorbitol levels were the highest in the diabetic sedentary no-insulin group. Diabetic sedentary rats receiving insulin had similar sorbitol levels to control sedentary rats. Endurance exercise did not significantly affect sorbitol levels. These results indicate that insulin treatment lowers sorbitol in skeletal muscle; therefore sorbitol accumulation is probably not related to muscle dysfunction in insulin-treated diabetic individuals. Endurance exercise did not influence intramuscular sorbitol values as strongly as insulin. PMID:20016800

  7. Metabolic effects of the iodothyronine functional analogue TRC150094 on the liver and skeletal muscle of high-fat diet fed overweight rats: an integrated proteomic study.

    Science.gov (United States)

    Silvestri, Elena; Glinni, Daniela; Cioffi, Federica; Moreno, Maria; Lombardi, Assunta; de Lange, Pieter; Senese, Rosalba; Ceccarelli, Michele; Salzano, Anna Maria; Scaloni, Andrea; Lanni, Antonia; Goglia, Fernando

    2012-07-06

    A novel functional iodothyronine analogue, TRC150094, which has a much lower potency toward thyroid hormone receptor (α1/β1) activation than triiodothyronine, has been shown to be effective at reducing adiposity in rats simultaneously receiving a high-fat diet (HFD). Here, by combining metabolic, functional and proteomic analysis, we studied how the hepatic and skeletal muscle phenotypes might respond to TRC150094 treatment in HFD-fed overweight rats. Drug treatment increased both the liver and skeletal muscle mitochondrial oxidative capacities without altering mitochondrial efficiency. Coherently, in terms of individual respiratory in-gel activity, blue-native analysis revealed an increased activity of complex V in the liver and of complexes II and V in tibialis muscle in TCR150094-treated animals. Subsequently, the identification of differentially expressed proteins and the analysis of their interrelations gave an integrated view of the phenotypic/metabolic adaptations occurring in the liver and muscle proteomes during drug treatment. TRC150094 significantly altered the expression of several proteins involved in key liver metabolic pathways, including amino acid and nitrogen metabolism, and fructose and mannose metabolism. The canonical pathways most strongly influenced by TRC150094 in tibialis muscle included glycolysis and gluconeogenesis, amino acid, fructose and mannose metabolism, and cell signaling. The phenotypic/metabolic influence of TRC150094 on the liver and skeletal muscle of HFD-fed overweight rats suggests the potential clinical application of this iodothyronine analogue in ameliorating metabolic risk parameters altered by diet regimens.

  8. Establishment of bipotent progenitor cell clone from rat skeletal muscle.

    Science.gov (United States)

    Murakami, Yousuke; Yada, Erica; Nakano, Shin-ichi; Miyagoe-Suzuki, Yuko; Hosoyama, Tohru; Matsuwaki, Takashi; Yamanouchi, Keitaro; Nishihara, Masugi

    2011-12-01

    The present study describes the isolation, cloning and characterization of adipogenic progenitor cells from rat skeletal muscle. Among the obtained 10 clones, the most highly adipogenic progenitor, 2G11 cells, were further characterized. In addition to their adipogenicity, 2G11 cells retain myogenic potential as revealed by formation of multinucleated myotubes when co-cultured with myoblasts. 2G11 cells were resistant to an inhibitory effect of basic fibroblast growth factor on adipogenesis, while adipogenesis of widely used preadipogenic cell line, 3T3-L1 cells, was suppressed almost completely by the same treatment. In vivo transplantation experiments revealed that 2G11 cells are able to possess both adipogenicity and myogenicity in vivo. These results indicate the presence of bipotent progenitor cells in rat skeletal muscle, and suggest that such cells may contribute to ectopic fat formation in skeletal muscle. © 2011 The Authors. Animal Science Journal © 2011 Japanese Society of Animal Science.

  9. A PGC-1α- and muscle fibre type-related decrease in markers of mitochondrial oxidative metabolism in skeletal muscle of humans with inherited insulin resistance

    DEFF Research Database (Denmark)

    Kristensen, Jonas Møller; Skov, Vibe; Petersson, Stine Juhl

    2014-01-01

    Insulin resistance in obesity and type 2 diabetes is related to abnormalities in mitochondrial oxidative phosphorylation (OxPhos) in skeletal muscle. We tested the hypothesis that mitochondrial oxidative metabolism is impaired in muscle of patients with inherited insulin resistance and defective...

  10. Increased mitochondrial energy efficiency in skeletal muscle after long-term fasting: its relevance to animal performance.

    Science.gov (United States)

    Bourguignon, Aurore; Rameau, Anaïs; Toullec, Gaëlle; Romestaing, Caroline; Roussel, Damien

    2017-07-01

    In the final stage of fasting, skeletal muscle mass and protein content drastically decrease when the maintenance of efficient locomotor activity becomes crucial for animals to reactivate feeding behaviour and survive a very long period of starvation. As mitochondrial metabolism represents the main physiological link between the endogenous energy store and animal performance, the aim of this study was to determine how a very long, natural period of fasting affected skeletal muscle mitochondrial bioenergetics in king penguin ( Aptenodytes patagonicus ) chicks. Rates of mitochondrial oxidative phosphorylation were measured in pectoralis permeabilized fibres and isolated mitochondria. Mitochondrial ATP synthesis efficiency and the activities of respiratory chain complexes were measured in mitochondria isolated from pectoralis muscle. Results from long-term (4-5 months) naturally fasted chicks were compared with those from short-term (10 day) fasted birds. The respiratory activities of muscle fibres and isolated mitochondria were reduced by 60% and 45%, respectively, on average in long-term fasted chicks compared with short-term fasted birds. Oxidative capacity and mitochondrial content of pectoralis muscle were lowered by long-term fasting. Bioenergetic analysis of pectoralis muscle also revealed that mitochondria were, on average, 25% more energy efficient in the final stage of fasting (4-5 months) than after 10 days of fasting (short-term fasted birds). These results suggest that the strong reduction in respiratory capacity of pectoralis muscle was partly alleviated by increased mitochondrial ATP synthesis efficiency. Such oxidative phosphorylation optimization can impact animal performance, e.g. the metabolic cost of locomotion or the foraging efficiency. © 2017. Published by The Company of Biologists Ltd.

  11. Sirtuin-3 (Sirt3) regulates skeletal muscle metabolism and insulin signaling via altered mitochondrial oxidation and reactive oxygen species production

    DEFF Research Database (Denmark)

    Jing, Enxuan; Emanuelli, Brice; Hirschey, Matthew D

    2011-01-01

    Sirt3 is a member of the sirtuin family of protein deacetylases that is localized in mitochondria and regulates mitochondrial function. Sirt3 expression in skeletal muscle is decreased in models of type 1 and type 2 diabetes and regulated by feeding, fasting, and caloric restriction. Sirt3 knockout...... mice exhibit decreased oxygen consumption and develop oxidative stress in skeletal muscle, leading to JNK activation and impaired insulin signaling. This effect is mimicked by knockdown of Sirt3 in cultured myoblasts, which exhibit reduced mitochondrial oxidation, increased reactive oxygen species......, activation of JNK, increased serine and decreased tyrosine phosphorylation of IRS-1, and decreased insulin signaling. Thus, Sirt3 plays an important role in diabetes through regulation of mitochondrial oxidation, reactive oxygen species production, and insulin resistance in skeletal muscle....

  12. Influence of erythrocyte oxygenation and intravascular ATP on resting and exercising skeletal muscle blood flow in humans with mitochondrial myopathy

    DEFF Research Database (Denmark)

    Jeppesen, Tina D; Vissing, John; González-Alonso, José

    2012-01-01

    Oxygen (O(2)) extraction is impaired in exercising skeletal muscle of humans with mutations of mitochondrial DNA (mtDNA), but the muscle hemodynamic response to exercise has never been directly investigated. This study sought to examine the extent to which human skeletal muscle perfusion can incr...

  13. The Pleiotropic Effect of Physical Exercise on Mitochondrial Dynamics in Aging Skeletal Muscle

    Directory of Open Access Journals (Sweden)

    Elena Barbieri

    2015-01-01

    Full Text Available Decline in human muscle mass and strength (sarcopenia is one of the principal hallmarks of the aging process. Regular physical exercise and training programs are certain powerful stimuli to attenuate the physiological skeletal muscle alterations occurring during aging and contribute to promote health and well-being. Although the series of events that led to these muscle adaptations are poorly understood, the mechanisms that regulate these processes involve the “quality” of skeletal muscle mitochondria. Aerobic/endurance exercise helps to maintain and improve cardiovascular fitness and respiratory function, whereas strength/resistance-exercise programs increase muscle strength, power development, and function. Due to the different effect of both exercises in improving mitochondrial content and quality, in terms of biogenesis, dynamics, turnover, and genotype, combined physical activity programs should be individually prescribed to maximize the antiaging effects of exercise.

  14. Insulin binding to individual rat skeletal muscles

    International Nuclear Information System (INIS)

    Koerker, D.J.; Sweet, I.R.; Baskin, D.G.

    1990-01-01

    Studies of insulin binding to skeletal muscle, performed using sarcolemmal membrane preparations or whole muscle incubations of mixed muscle or typical red (soleus, psoas) or white [extensor digitorum longus (EDL), gastrocnemius] muscle, have suggested that red muscle binds more insulin than white muscle. We have evaluated this hypothesis using cryostat sections of unfixed tissue to measure insulin binding in a broad range of skeletal muscles; many were of similar fiber-type profiles. Insulin binding per square millimeter of skeletal muscle slice was measured by autoradiography and computer-assisted densitometry. We found a 4.5-fold range in specific insulin tracer binding, with heart and predominantly slow-twitch oxidative muscles (SO) at the high end and the predominantly fast-twitch glycolytic (FG) muscles at the low end of the range. This pattern reflects insulin sensitivity. Evaluation of displacement curves for insulin binding yielded linear Scatchard plots. The dissociation constants varied over a ninefold range (0.26-2.06 nM). Binding capacity varied from 12.2 to 82.7 fmol/mm2. Neither binding parameter was correlated with fiber type or insulin sensitivity; e.g., among three muscles of similar fiber-type profile, the EDL had high numbers of low-affinity binding sites, whereas the quadriceps had low numbers of high-affinity sites. In summary, considerable heterogeneity in insulin binding was found among hindlimb muscles of the rat, which can be attributed to heterogeneity in binding affinities and the numbers of binding sites. It can be concluded that a given fiber type is not uniquely associated with a set of insulin binding parameters that result in high or low binding

  15. Oxidative stress and mitochondrial impairment can be separated from lipofuscin accumulation in aged human skeletal muscle

    DEFF Research Database (Denmark)

    Hütter, Eveline; Skovbro, Mette; Lener, Barbara

    2007-01-01

    According to the free radical theory of aging, reactive oxygen species (ROS) act as a driving force of the aging process, and it is generally believed that mitochondrial dysfunction is a major source of increased oxidative stress in tissues with high content of mitochondria, such as muscle or brain....... However, recent experiments in mouse models of premature aging have questioned the role of mitochondrial ROS production in premature aging. To address the role of mitochondrial impairment and ROS production for aging in human muscles, we have analyzed mitochondrial properties in muscle fibres isolated...... from the vastus lateralis of young and elderly donors. Mitochondrial respiratory functions were addressed by high-resolution respirometry, and ROS production was analyzed by in situ staining with the redox-sensitive dye dihydroethidium. We found that aged human skeletal muscles contain fully functional...

  16. Oxidative stress (glutathionylation and Na,K-ATPase activity in rat skeletal muscle.

    Directory of Open Access Journals (Sweden)

    Carsten Juel

    Full Text Available Changes in ion distribution across skeletal muscle membranes during muscle activity affect excitability and may impair force development. These changes are counteracted by the Na,K-ATPase. Regulation of the Na,K-ATPase is therefore important for skeletal muscle function. The present study investigated the presence of oxidative stress (glutathionylation on the Na,K-ATPase in rat skeletal muscle membranes.Immunoprecipitation with an anti-glutathione antibody and subsequent immunodetection of Na,K-ATPase protein subunits demonstrated 9.0±1.3% and 4.1±1.0% glutathionylation of the α isoforms in oxidative and glycolytic skeletal muscle, respectively. In oxidative muscle, 20.0±6.1% of the β1 units were glutathionylated, whereas 14.8±2.8% of the β2-subunits appear to be glutathionylated in glycolytic muscle. Treatment with the reducing agent dithiothreitol (DTT, 1 mM increased the in vitro maximal Na,K-ATPase activity by 19% (P<0.05 in membranes from glycolytic muscle. Oxidized glutathione (GSSG, 0-10 mM increased the in vitro glutathionylation level detected with antibodies, and decreased the in vitro maximal Na,K-ATPase activity in a dose-dependent manner, and with a larger effect in oxidative compared to glycolytic skeletal muscle.This study demonstrates the existence of basal glutathionylation of both the α and the β units of rat skeletal muscle Na,K-ATPase. In addition, the study suggests a negative correlation between glutathionylation levels and maximal Na,K-ATPase activity.Glutathionylation likely contributes to the complex regulation of Na,K-ATPase function in skeletal muscle. Especially, glutathionylation induced by oxidative stress may have a role in Na,K-ATPase regulation during prolonged muscle activity.

  17. Increased mitochondrial substrate sensitivity in skeletal muscle of patients with type 2 diabetes

    DEFF Research Database (Denmark)

    Larsen, S; Stride, N; Hey-Mogensen, Martin

    2011-01-01

    AIMS/HYPOTHESIS: Mitochondrial respiration has been linked to insulin resistance. We studied mitochondrial respiratory capacity and substrate sensitivity in patients with type 2 diabetes (patients), and obese and lean control participants. METHODS: Mitochondrial respiration was measured.......4). Substrate sensitivity for octanoyl-carnitine did not differ between groups. CONCLUSIONS/INTERPRETATION: Increased mitochondrial substrate sensitivity is seen in skeletal muscle from type 2 diabetic patients and is confined to non-lipid substrates. Respiratory capacity per mitochondrion is not decreased...... and maximal oxygen uptake (VO2) were also determined. Insulin sensitivity was determined with the isoglycaemic-hyperinsulinaemic clamp technique. RESULTS: Insulin sensitivity was different (p

  18. Wheat Germ Oil Attenuates Gamma Radiation- Induced Skeletal Muscles Damage in Rats

    International Nuclear Information System (INIS)

    Said, U.Z.; Saada, H.N.; Shedid, Sh.M.; Mahdy, E.M.E.; Shousha, W.Gh.

    2008-01-01

    Muscular strength is important in sport as well as in daily activities. Exposure to ionizing radiation is thought to increase oxidative stress and damage muscle tissue. Wheat germ oil is a natural unrefined vegetable oil. It is an excellent source of vitamin E, octacosanol, linoleic and linolenic essential fatty acids, which may be beneficial in neutralizing the free oxygen radicals. The present study was designed to investigate the efficacy of wheat germ oil, on radiation-induced oxidative damage in rats skeletal muscle. Wheat germ oil was supplemented orally via gavages to rats at a dose of 54 mg/ kg body weight/day for 14 successive days pre- and 7 post-exposure to 5 Gy (one shot dose) of whole body gamma irradiation. Animals were sacrificed 7, 14 and 21 days post radiation exposure. The results revealed that whole body gamma-irradiation of rats induces oxidative stress in skeletal muscles obvious by significant elevation in the level of thiobarbituric acid reactive substances (TBARS) associated with significant decreases in the content of reduced glutathione (GSE1), as well as decreases in superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities. Irradiated rats showed, also, significant decreases in creatine phosphokinase (CPK), glutamate dehydrogenase (GDH) and glucose-6-phosphate dehydrogenase (G-6-PD) activities. Furthermore, total iron, total copper and total calcium levels were significantly increased in skeletal muscles of irradiated rats group compared to control group. Wheat germ oil treated-irradiated rats showed significantly less sever damage and remarkable improvement in all the measured parameters, compared to irradiated rats. It could be concluded that wheat germ oil by attenuating radiation induced oxidative stress might play a role in maintaining skeletal muscle integrity

  19. Adaptive plasticity of skeletal muscle energetics in hibernating frogs: mitochondrial proton leak during metabolic depression.

    Science.gov (United States)

    Boutilier, Robert G; St-Pierre, Julie

    2002-08-01

    The common frog (Rana temporaria) spends the coldest months of each year overwintering in ice-covered ponds where temperatures can vary from 0.5 to 4.0 degrees C. Over the course of a winter season, the animals enter progressively into a state of metabolic depression that relies almost exclusively on aerobic production of ATP. However, if aerobic metabolism is threatened, for example by increasingly hypoxic conditions, decreases in the animal's metabolic rate can reach upwards of 75% compared with the 50% decrease seen during normoxia. Under these conditions, the major proportion of the overall reduction in whole-animal metabolic rate can be accounted for by metabolic suppression of the skeletal muscle (which makes up approximately 40% of body mass). Little is known about the properties of mitochondria during prolonged periods of metabolic depression, so we have examined several aspects of mitochondrial metabolism in the skeletal muscle of frogs over periods of hibernation of up to 4 months. Mitochondria isolated from the skeletal muscle of frogs hibernating in hypoxic water show a considerable reorganisation of function compared with those isolated from normoxic submerged animals at the same temperature (3 degrees C). Both the active (state 3) and resting (state 4) respiration rates of mitochondria decrease during hypoxic, but not normoxic, hibernation. In addition, the affinity of mitochondria for oxygen increases during periods of acute hypoxic stress during normoxic hibernation as well as during long-term hibernation in hypoxic water. The decrease in mitochondrial state 4 respiration rates during hypoxic hibernation evidently occurs through a reduction in electron-transport chain activity, not through a lowered proton conductance of the mitochondrial inner membrane. The reduced aerobic capacity of frog skeletal muscle during hypoxic hibernation is accompanied by lowered activities of key enzymes of mitochondrial metabolism caused by changes in the intrinsic

  20. Dissemination of Walker 256 carcinoma cells to rat skeletal muscle

    International Nuclear Information System (INIS)

    Ueoka, H.; Hayashi, K.; Namba, T.; Grob, D.

    1986-01-01

    After injection of 10 6 Walker 256 carcinoma cells labelled with 125 I-5-iodo-2'-deoxyuridine into the tail vein, peak concentration in skeletal muscle was 46 cells/g at 60 minutes, which was lower than 169202, 1665, 555, 198 and 133 cells/g, respectively, at 30 or 60 minutes in lung, liver, spleen, kidney and heart. Because skeletal muscle constitutes 37.4% of body weight, the total number of tumor cells was 2323 cells, which was much greater than in spleen, kidney and heart with 238, 271, and 85 cells, respectively, and only less than in lung and liver, at 222857 and 11700 cells, respectively. The total number in skeletal muscle became greater than in liver at 4 hours and than in lung at 24 hours. Ten minutes after injection of 7.5 x 10 6 Walker 256 carcinoma cells into the abdominal aorta of rats, a mean of 31 colony-forming cells were recovered from the gastrocnemius, while 106 cells were recovered from the lung after injection into the tail vein. These results indicate that a large number of viable tumor cells can be arrested in skeletal muscle through circulation. The rare remote metastasis of malignancies into skeletal muscle despite constantly circulating tumor cells does not appear to be due to poor dissemination of tumor cells into muscle but due to unhospitable environment of skeletal muscle

  1. EFFECTS OF PHYSICAL EXERCISES ON TRIACYLGLYCEROL LEVEL IN SKELETAL MUSCLES IN DIETARY-INDUCED OBESE RATS

    Directory of Open Access Journals (Sweden)

    I. Yu. Yakimovich

    2014-01-01

    Full Text Available The accumulation of triacylglycerol in peripheral tissues is one of mechanisms of insulin resistance. This paper presents the investigation of the influence of aerobic and anaerobic physical exercises on triacylglycerol level in skeletal muscles and on insulin resistance in dietary-induced obese rats. It is estimated that a high-energy (HE diet causes the accumulation of triacylglycerols in skeletal muscles that leads to high resistance to insulin. Aerobic and anaerobic physical exercises reduce the level of triacylglycerols in skeletal  muscles  and  raise  sensitivity to  insulin  in  obese  rats.  Physical  exercises  raise  the  level  of triacylglycerols in skeletal muscles in standard-diet rats that probably is the adaptation to high energy expenditure, but does not lead to high insulin resistance.

  2. Effects of growth hormone on morphology of cardiac muscle and skeletal muscle and hormone levels in rats

    International Nuclear Information System (INIS)

    Yang Ping; Liu Cong; Meng Fanbo; Zhu Jinming; Ni Jinsong; Zhou Hong; Tang Yubo

    2005-01-01

    Objective: To study the effects of growth hormone (GH) on morphology of cardiac muscle and skeletal muscle and hormone levels in Wistar rats. Methods: The GH was given with subcutaneous injection for 15 days, the level of serum GH was determined by radiation-immune method; the body weight and the ratio of organ weight to body weight were determined; the cell appearances of cardiac muscle and skeletal muscle were observed under microscope. the control group was set up. Results; The level of serum GH and rat body weight in experimental group were obviously higher than that in the control group, but the ratio of organ weight to body weight was not obviously different in two groups; musculature hypertrophy and cell nucleolus increasing were observed under microscopy, there were no capillary vessel hyperplasia and inflammatory soakage. Conclusion: GH can induce hypertrophy of cardiac muscle cells and skeletal muscle cells but not interstitial proliferation. (authors)

  3. Properties of 5'-deiodinase of 3,3',5'-triiodothyronine in rat skeletal muscle

    International Nuclear Information System (INIS)

    Tsukahara, Fujiko; Nomoto, Teruko; Maeda, Michiko

    1989-01-01

    To characterize rT 3 5'-deiodinase (5'D) in rat skeletal muscle, the effects of altered thyroid status and PTU on rT 3 f'D were studied. rT 3 5'D activity was measured by incubating homogenates of rat skeletal muscle with [ 125 ]rT 3 , iodine labelled in the outer ring, in the presence of 20 mmol/l DL-dithiothreitol. This activity was observed to increase significantly 24 h after a single sc injection of T 3 (75μg/kg). The increase following the daily administration of this drug (15 or 75 μ/kg) for 3 and 14 days was dependent on the dose and number of previous days of injection. A significant decrease in activity was observed 2 weeks after thyroidectomy. The addition of 0.1 mmol/l 6-n-propyl-2-thiouracil (PTU) to the incubation medium in vitro caused a marked reduction in the activity in homogenates of skeletal muscle from hypothyroid, euthyroid and hyperthyroid rats. PTU, pressent at 0.05% in the drinking water for 2 weeks virtually abolished it. The properties of rT 3 5'D in rat skeletal muscle thus appear to be essentially the same as those of type I enzyme with respect to response toward altered thyroid status and PTU. (author)

  4. SPRINT-INTERVAL TRAINING INDUCES HEAT SHOCK PROTEIN 72 IN RAT SKELETAL MUSCLES

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    Yuji Ogura

    2006-06-01

    Full Text Available Previous studies have demonstrated that endurance exercise training increases the level of heat shock proteins (HSPs in skeletal muscles. However, little attention has been drawn to the effects of high intensity-short duration exercise, or sprint- interval training (SIT on HSP72 level in rat skeletal muscles. This study performed to test the hypothesis that the SIT would induce the HSP72 in fast and slow skeletal muscles of rats. Young male Wistar rats (8 weeks old were randomly assigned to a control (CON or a SIT group (n = 8/group. Animals in the SIT group were trained (1 min/sprint, 6~10 sets/day and 5~6 days/week on a treadmill for 9 weeks. After the training period, HSP72 levels in the plantaris (fast and soleus (slow muscles were analyzed by Western blotting method. Enzyme activities (hexokinase, phosphofructokinase and citrate synthase and histochemical properties (muscle fiber type compositions and cross sectional area in both muscles were also determined. The SIT resulted in significantly (p < 0.05 higher levels of HSP72 in both the plantaris and soleus muscles compared to the CON group, with the plantaris producing a greater HSP72 increase than the soleus (plantaris; 550 ± 116%, soleus; 26 ± 8%, p < 0.05. Further, there were bioenergetic improvements, fast-to-slow shift of muscle fiber composition and hypertrophy in the type IIA fiber only in the plantaris muscle. These findings indicate that the SIT program increases HSP72 level of the rat hindlimb muscles, and the SIT-induced accumulation of HSP72 differs between fast and slow muscles

  5. Optimizing hyaluronidase dose and plasmid DNA delivery greatly improves gene electrotransfer efficiency in rat skeletal muscle

    DEFF Research Database (Denmark)

    Åkerström, Thorbjörn; Vedel, Kenneth; Needham Andersen, Josefine

    2015-01-01

    Transfection of rat skeletal muscle in vivo is a widely used research model. However, gene electrotransfer protocols have been developed for mice and yield variable results in rats. We investigated whether changes in hyaluronidase pre-treatment and plasmid DNA delivery can improve transfection...... with a homogenous distribution. We also show that transfection was stable over five weeks of regular exercise or inactivity. Our findings show that species-specific plasmid DNA delivery and hyaluronidase pre-treatment greatly improves transfection efficiency in rat skeletal muscle....... efficiency in rat skeletal muscle. We found that pre-treating the muscle with a hyaluronidase dose suitable for rats (0.56. U/g b.w.) prior to plasmid DNA injection increased transfection efficiency by >200% whereas timing of the pre-treatment did not affect efficiency. Uniformly distributing plasmid DNA...

  6. Hypercaloric cafeteria-like diet induced UCP3 gene expression in skeletal muscle is impaired by hypothyroidism

    Directory of Open Access Journals (Sweden)

    Christoffolete M.A.

    2004-01-01

    Full Text Available The uncoupling protein UCP3 belongs to a family of mitochondrial carriers located in the inner mitochondrial membrane of certain cell types. It is expressed almost exclusively at high levels in skeletal muscle and its physiological role has not been fully determined in this tissue. In the present study we have addressed the possible interaction between a hypercaloric diet and thyroid hormone (T3, which are strong stimulators of UCP3 gene expression in skeletal muscle. Male Wistar rats weighing 180 ± 20 g were rendered hypothyroid by thyroidectomy and the addition of methimazole (0.05%; w/v to drinking water after surgery. The rats were fed a hypercaloric cafeteria diet (68% carbohydrates, 13% protein and 18% lipids for 10 days and sacrificed by decapitation. Subsequently, the gastrocnemius muscle was dissected, total RNA was isolated with Trizol? and UCP3 gene expression was determined by Northern blotting using a specific probe. Statistical analysis was performed by one-way analysis of variance (ANOVA followed by the Student-Newman-Keuls post-test. Skeletal muscle UCP3 gene expression was decreased by 60% in hypothyroid rats and UCP3 mRNA expression was increased 70% in euthyroid cafeteria-fed rats compared to euthyroid chow-fed animals, confirming previous studies. Interestingly, the cafeteria diet was unable to stimulate UCP3 gene expression in hypothyroid animals (40% lower as compared to euthyroid cafeteria-fed animals. The results show that a hypercaloric diet is a strong stimulator of UCP3 gene expression in skeletal muscle and requires T3 for an adequate action.

  7. Simvastatin effects on skeletal muscle

    DEFF Research Database (Denmark)

    Larsen, Steen; Stride, Nis; Hey-Mogensen, Martin

    2013-01-01

    Glucose tolerance and skeletal muscle coenzyme Q(10) (Q(10)) content, mitochondrial density, and mitochondrial oxidative phosphorylation (OXPHOS) capacity were measured in simvastatin-treated patients (n = 10) and in well-matched control subjects (n = 9)....

  8. Patients with type 2 diabetes have normal mitochondrial function in skeletal muscle

    DEFF Research Database (Denmark)

    Boushel, R; Gnaiger, E; Schjerling, P

    2007-01-01

    AIMS/HYPOTHESIS: Insulin resistance and type 2 diabetes are associated with mitochondrial dysfunction. The aim of the present study was to test the hypothesis that oxidative phosphorylation and electron transport capacity are diminished in the skeletal muscle of type 2 diabetic subjects......, as a result of a reduction in the mitochondrial content. MATERIALS AND METHODS: The O(2) flux capacity of permeabilised muscle fibres from biopsies of the quadriceps in healthy subjects (n = 8; age 58 +/- 2 years [mean+/-SEM]; BMI 28 +/- 1 kg/m(2); fasting plasma glucose 5.4 +/- 0.2 mmol/l) and patients...... with type 2 diabetes (n = 11; age 62 +/- 2 years; BMI 32 +/- 2 kg/m(2); fasting plasma glucose 9.0 +/- 0.8 mmol/l) was measured by high-resolution respirometry. RESULTS: O(2) flux expressed per mg of muscle (fresh weight) during ADP-stimulated state 3 respiration was lower (p type 2...

  9. The relationship between skeletal muscle mitochondrial citrate synthase activity and whole body oxygen uptake adaptations in response to exercise training

    DEFF Research Database (Denmark)

    Vigelsø, Andreas; Andersen, Nynne B; Dela, Flemming

    2014-01-01

    Citrate synthase (CS) activity is a validated biomarker for mitochondrial density in skeletal muscle. CS activity is also used as a biochemical marker of the skeletal muscle oxidative adaptation to a training intervention, and a relationship between changes in whole body aerobic capacity and chan......Citrate synthase (CS) activity is a validated biomarker for mitochondrial density in skeletal muscle. CS activity is also used as a biochemical marker of the skeletal muscle oxidative adaptation to a training intervention, and a relationship between changes in whole body aerobic capacity...... and changes in CS activity is often assumed. However, this relationship and absolute values of CS and maximal oxygen uptake (V.O2max) has never been assessed across different studies. A systematic PubMed search on literature published from 1983 to 2013 was performed. The search profile included: citrate...... and CS activity. 70 publications with 97 intervention groups were included. There was a positive (r = 0.45) correlation (P

  10. Skeletal muscle and hormonal adaptation to physical training in the rat

    DEFF Research Database (Denmark)

    Henriksson, J; Svedenhag, J; Richter, Erik

    1985-01-01

    The main purpose of the present study was to test the hypothesis that adrenergic stimulation of muscle fibres during exercise is a major stimulus for the training-induced enhancement of skeletal muscle respiratory capacity. Therefore, Sprague-Dawley rats either underwent bilateral surgical ablati...

  11. Regional anatomic differences in skeletal muscle mitochondrial respiration in type 2 diabetes and obesity

    DEFF Research Database (Denmark)

    Rabøl, R; Larsen, S; Højberg, P M V

    2010-01-01

    respiration and markers of mitochondrial content in skeletal muscle of arm and leg in patients with T2DM and obese control subjects. Patients: Ten patients with T2DM (age, 52.3 +/- 2.7 yr; body mass index, 30.1 +/- 1.2 kg/m(2)) (mean +/- se) were studied after a 2-wk washout period of oral antihyperglycemic...... agents. Ten control subjects (age, 54.3 +/- 2.8 yr; body mass index, 30.4 +/- 1.2 kg/m(2)) with normal fasting and 2-h oral glucose tolerance test blood glucose levels were also included. Main Outcome Measure: We measured mitochondrial respiration in saponin-treated skinned muscle fibers from biopsies...

  12. Protective effects of myricetin on acute hypoxia-induced exercise intolerance and mitochondrial impairments in rats.

    Directory of Open Access Journals (Sweden)

    Dan Zou

    Full Text Available Exercise tolerance is impaired in hypoxia. The aim of this study was to evaluate the effects of myricetin, a dietary flavonoid compound widely found in fruits and vegetables, on acute hypoxia-induced exercise intolerance in vivo and in vitro.Male rats were administered myricetin or vehicle for 7 days and subsequently spent 24 hours at a barometric pressure equivalent to 5000 m. Exercise capacity was then assessed through the run-to-fatigue procedure, and mitochondrial morphology in skeletal muscle cells was observed by transmission electron microscopy (TEM. The enzymatic activities of electron transfer complexes were analyzed using an enzyme-linked immuno-sorbent assay (ELISA. mtDNA was quantified by real-time-PCR. Mitochondrial membrane potential was measured by JC-1 staining. Protein expression was detected through western blotting, immunohistochemistry, and immunofluorescence.Myricetin supplementation significantly prevented the decline of run-to-fatigue time of rats in hypoxia, and attenuated acute hypoxia-induced mitochondrial impairment in skeletal muscle cells in vivo and in vitro by maintaining mitochondrial structure, mtDNA content, mitochondrial membrane potential, and activities of the respiratory chain complexes. Further studies showed that myricetin maintained mitochondrial biogenesis in skeletal muscle cells under hypoxic conditions by up-regulating the expressions of mitochondrial biogenesis-related regulators, in addition, AMP-activated protein kinase(AMPK plays a crucial role in this process.Myricetin may have important applications for improving physical performance under hypoxic environment, which may be attributed to the protective effect against mitochondrial impairment by maintaining mitochondrial biogenesis.

  13. Effects of exercise training on circulating and skeletal muscle renin-angiotensin system in chronic heart failure rats.

    Science.gov (United States)

    Gomes-Santos, Igor Lucas; Fernandes, Tiago; Couto, Gisele Kruger; Ferreira-Filho, Julio César Ayres; Salemi, Vera Maria Cury; Fernandes, Fernanda Barrinha; Casarini, Dulce Elena; Brum, Patricia Chakur; Rossoni, Luciana Venturini; de Oliveira, Edilamar Menezes; Negrao, Carlos Eduardo

    2014-01-01

    Accumulated evidence shows that the ACE-AngII-AT1 axis of the renin-angiotensin system (RAS) is markedly activated in chronic heart failure (CHF). Recent studies provide information that Angiotensin (Ang)-(1-7), a metabolite of AngII, counteracts the effects of AngII. However, this balance between AngII and Ang-(1-7) is still little understood in CHF. We investigated the effects of exercise training on circulating and skeletal muscle RAS in the ischemic model of CHF. Male Wistar rats underwent left coronary artery ligation or a Sham operation. They were divided into four groups: 1) Sedentary Sham (Sham-S), 2) exercise-trained Sham (Sham-Ex), sedentary CHF (CHF-S), and exercise-trained CHF (CHF-Ex). Angiotensin concentrations and ACE and ACE2 activity in the circulation and skeletal muscle (soleus and plantaris) were quantified. Skeletal muscle ACE and ACE2 protein expression, and AT1, AT2, and Mas receptor gene expression were also evaluated. CHF reduced ACE2 serum activity. Exercise training restored ACE2 and reduced ACE activity in CHF. Exercise training reduced plasma AngII concentration in both Sham and CHF rats and increased the Ang-(1-7)/AngII ratio in CHF rats. CHF and exercise training did not change skeletal muscle ACE and ACE2 activity and protein expression. CHF increased AngII levels in both soleus and plantaris muscle, and exercise training normalized them. Exercise training increased Ang-(1-7) in the plantaris muscle of CHF rats. The AT1 receptor was only increased in the soleus muscle of CHF rats, and exercise training normalized it. Exercise training increased the expression of the Mas receptor in the soleus muscle of both exercise-trained groups, and normalized it in plantaris muscle. Exercise training causes a shift in RAS towards the Ang-(1-7)-Mas axis in skeletal muscle, which can be influenced by skeletal muscle metabolic characteristics. The changes in RAS circulation do not necessarily reflect the changes occurring in the RAS of skeletal

  14. GSNOR Deficiency Enhances In Situ Skeletal Muscle Strength, Fatigue Resistance, and RyR1 S-Nitrosylation Without Impacting Mitochondrial Content and Activity

    Science.gov (United States)

    Moon, Younghye; Cao, Yenong; Zhu, Jingjing; Xu, Yuanyuan; Balkan, Wayne; Buys, Emmanuel S.; Diaz, Francisca; Kerrick, W. Glenn; Hare, Joshua M.

    2017-01-01

    Abstract Aim: Nitric oxide (NO) plays important, but incompletely defined roles in skeletal muscle. NO exerts its regulatory effects partly though S-nitrosylation, which is balanced by denitrosylation by enzymes such as S-nitrosoglutathione reductase (GSNOR), whose functions in skeletal muscle remain to be fully deciphered. Results: GSNOR null (GSNOR−/−) tibialis anterior (TA) muscles showed normal growth and were stronger and more fatigue resistant than controls in situ. However, GSNOR−/− lumbrical muscles showed normal contractility and Ca2+ handling in vitro, suggesting important differences in GSNOR function between muscles or between in vitro and in situ environments. GSNOR−/− TA muscles exhibited normal mitochondrial content, and capillary densities, but reduced type IIA fiber content. GSNOR inhibition did not impact mitochondrial respiratory complex I, III, or IV activities. These findings argue that enhanced GSNOR−/− TA contractility is not driven by changes in mitochondrial content or activity, fiber type, or blood vessel density. However, loss of GSNOR led to RyR1 hypernitrosylation, which is believed to increase muscle force output under physiological conditions. cGMP synthesis by soluble guanylate cyclase (sGC) was decreased in resting GSNOR−/− muscle and was more responsive to agonist (DETANO, BAY 41, and BAY 58) stimulation, suggesting that GSNOR modulates cGMP production in skeletal muscle. Innovation: GSNOR may act as a “brake” on skeletal muscle contractile performance under physiological conditions by modulating nitrosylation/denitrosylation balance. Conclusions: GSNOR may play important roles in skeletal muscle contractility, RyR1 S-nitrosylation, fiber type specification, and sGC activity. Antioxid. Redox Signal. 26, 165–181. PMID:27412893

  15. Resveratrol improves high-fat diet induced insulin resistance by rebalancing subsarcolemmal mitochondrial oxidation and antioxidantion.

    Science.gov (United States)

    Haohao, Zhang; Guijun, Qin; Juan, Zheng; Wen, Kong; Lulu, Chen

    2015-03-01

    Although resveratrol (RES) is thought to be a key regulator of insulin sensitivity in rodents, the exact mechanism underlying this effect remains unclear. Therefore, we sought to investigate how RES affects skeletal muscle oxidative and antioxidant levels of subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondrial populations in high-fat diet (HFD)-induced insulin resistance (IR) rats. Systemic and skeletal muscle insulin sensitivity together with expressions of several genes related to mitochondrial biogenesis and skeletal muscle SIRT1, SIRT3 protein levels were studied in rats fed a normal diet, a HFD, and a HFD with intervention of RES for 8 weeks. Oxidative stress levels and antioxidant enzyme activities were assessed in SS and IMF mitochondria. HFD fed rats exhibited obvious systemic and skeletal muscle IR as well as decreased SIRT1 and SIRT3 expressions, mitochondrial DNA (mtDNA), and mitochondrial biogenesis (p diet induced IR, increased SIRT1 and SIRT3 expressions, mtDNA, and mitochondrial biogenesis (p competence in HFD rats.

  16. Exercise training during chemotherapy preserves skeletal muscle fiber area, capillarization, and mitochondrial content in patients with breast cancer.

    Science.gov (United States)

    Mijwel, Sara; Cardinale, Daniele A; Norrbom, Jessica; Chapman, Mark; Ivarsson, Niklas; Wengström, Yvonne; Sundberg, Carl Johan; Rundqvist, Helene

    2018-05-11

    Exercise has been suggested to ameliorate the detrimental effects of chemotherapy on skeletal muscle. The aim of this study was to compare the effects of different exercise regimens with usual care on skeletal muscle morphology and mitochondrial markers in patients being treated with chemotherapy for breast cancer. Specifically, we compared moderate-intensity aerobic training combined with high-intensity interval training (AT-HIIT) and resistance training combined with high-intensity interval training (RT-HIIT) with usual care (UC). Resting skeletal muscle biopsies were obtained pre- and postintervention from 23 randomly selected women from the OptiTrain breast cancer trial who underwent RT-HIIT, AT-HIIT, or UC for 16 wk. Over the intervention, citrate synthase activity, muscle fiber cross-sectional area, capillaries per fiber, and myosin heavy chain isoform type I were reduced in UC, whereas RT-HIIT and AT-HIIT were able to counteract these declines. AT-HIIT promoted up-regulation of the electron transport chain protein levels vs. UC. RT-HIIT favored satellite cell count vs. UC and AT-HIIT. There was a significant association between change in citrate synthase activity and self-reported fatigue. AT-HIIT and RT-HIIT maintained or improved markers of skeletal muscle function compared with the declines found in the UC group, indicating a sustained trainability in addition to the preservation of skeletal muscle structural and metabolic characteristics during chemotherapy. These findings highlight the importance of supervised exercise programs for patients with breast cancer during chemotherapy.-Mijwel, S., Cardinale, D. A., Norrbom, J., Chapman, M., Ivarsson, N., Wengström, Y., Sundberg, C. J., Rundqvist, H. Exercise training during chemotherapy preserves skeletal muscle fiber area, capillarization, and mitochondrial content in patients with breast cancer.

  17. AMPK in skeletal muscle function and metabolism

    DEFF Research Database (Denmark)

    Kjøbsted, Rasmus; Hingst, Janne Rasmuss; Fentz, Joachim

    2018-01-01

    Skeletal muscle possesses a remarkable ability to adapt to various physiologic conditions. AMPK is a sensor of intracellular energy status that maintains energy stores by fine-tuning anabolic and catabolic pathways. AMPK's role as an energy sensor is particularly critical in tissues displaying...... highly changeable energy turnover. Due to the drastic changes in energy demand that occur between the resting and exercising state, skeletal muscle is one such tissue. Here, we review the complex regulation of AMPK in skeletal muscle and its consequences on metabolism (e.g., substrate uptake, oxidation......, and storage as well as mitochondrial function of skeletal muscle fibers). We focus on the role of AMPK in skeletal muscle during exercise and in exercise recovery. We also address adaptations to exercise training, including skeletal muscle plasticity, highlighting novel concepts and future perspectives...

  18. Gene expression changes of single skeletal muscle fibers in response to modulation of the mitochondrial calcium uniporter (MCU

    Directory of Open Access Journals (Sweden)

    Francesco Chemello

    2015-09-01

    Full Text Available The mitochondrial calcium uniporter (MCU gene codifies for the inner mitochondrial membrane (IMM channel responsible for mitochondrial Ca2+ uptake. Cytosolic Ca2+ transients are involved in sarcomere contraction through cycles of release and storage in the sarcoplasmic reticulum. In addition cytosolic Ca2+ regulates various signaling cascades that eventually lead to gene expression reprogramming. Mitochondria are strategically placed in close contact with the ER/SR, thus cytosolic Ca2+ transients elicit large increases in the [Ca2+] of the mitochondrial matrix ([Ca2+]mt. Mitochondrial Ca2+ uptake regulates energy production and cell survival. In addition, we recently showed that MCU-dependent mitochondrial Ca2+ uptake controls skeletal muscle trophism. In the same report, we dissected the effects of MCU-dependent mitochondrial Ca2+ uptake on gene expression through microarray gene expression analysis upon modulation of MCU expression by in vivo AAV infection. Analyses were performed on single skeletal muscle fibers at two time points (7 and 14 days post-AAV injection. Raw and normalized data are available on the GEO database (http://www.ncbi.nlm.nih.gov/geo/ (GSE60931.

  19. Insulin alleviates degradation of skeletal muscle protein by inhibiting the ubiquitin-proteasome system in septic rats.

    Science.gov (United States)

    Chen, Qiyi; Li, Ning; Zhu, Weiming; Li, Weiqin; Tang, Shaoqiu; Yu, Wenkui; Gao, Tao; Zhang, Juanjuan; Li, Jieshou

    2011-06-03

    Hypercatabolism is common under septic conditions. Skeletal muscle is the main target organ for hypercatabolism, and this phenomenon is a vital factor in the deterioration of recovery in septic patients. In skeletal muscle, activation of the ubiquitin-proteasome system plays an important role in hypercatabolism under septic status. Insulin is a vital anticatabolic hormone and previous evidence suggests that insulin administration inhibits various steps in the ubiquitin-proteasome system. However, whether insulin can alleviate the degradation of skeletal muscle protein by inhibiting the ubiquitin-proteasome system under septic condition is unclear. This paper confirmed that mRNA and protein levels of the ubiquitin-proteasome system were upregulated and molecular markers of skeletal muscle proteolysis (tyrosine and 3-methylhistidine) simultaneously increased in the skeletal muscle of septic rats. Septic rats were infused with insulin at a constant rate of 2.4 mU.kg-1.min-1 for 8 hours. Concentrations of mRNA and proteins of the ubiquitin-proteasome system and molecular markers of skeletal muscle proteolysis were mildly affected. When the insulin infusion dose increased to 4.8 mU.kg-1.min-1, mRNA for ubiquitin, E2-14 KDa, and the C2 subunit were all sharply downregulated. At the same time, the levels of ubiquitinated proteins, E2-14KDa, and the C2 subunit protein were significantly reduced. Tyrosine and 3-methylhistidine decreased significantly. We concluded that the ubiquitin-proteasome system is important skeletal muscle hypercatabolism in septic rats. Infusion of insulin can reverse the detrimental metabolism of skeletal muscle by inhibiting the ubiquitin-proteasome system, and the effect is proportional to the insulin infusion dose.

  20. Exercise training protects against aging-induced mitochondrial fragmentation in mouse skeletal muscle in a PGC-1α dependent manner

    DEFF Research Database (Denmark)

    Halling, Jens Frey; Jørgensen, Stine Ringholm; Olesen, Jesper

    2017-01-01

    Aging is associated with impaired mitochondrial function, whereas exercise training enhances mitochondrial content and function in part through activation of PGC-1α. Mitochondria form dynamic networks regulated by fission and fusion with profound effects on mitochondrial functions, yet the effect...... evidence that exercise training rescues aging-induced mitochondrial fragmentation in skeletal muscle by suppressing mitochondrial fission protein expression in a PGC-1α dependent manner....

  1. Disrupted Skeletal Muscle Mitochondrial Dynamics, Mitophagy, and Biogenesis during Cancer Cachexia: A Role for Inflammation

    Science.gov (United States)

    VanderVeen, Brandon N.; Fix, Dennis K.

    2017-01-01

    Chronic inflammation is a hallmark of cancer cachexia in both patients and preclinical models. Cachexia is prevalent in roughly 80% of cancer patients and accounts for up to 20% of all cancer-related deaths. Proinflammatory cytokines IL-6, TNF-α, and TGF-β have been widely examined for their regulation of cancer cachexia. An established characteristic of cachectic skeletal muscle is a disrupted capacity for oxidative metabolism, which is thought to contribute to cancer patient fatigue, diminished metabolic function, and muscle mass loss. This review's primary objective is to highlight emerging evidence linking cancer-induced inflammation to the dysfunctional regulation of mitochondrial dynamics, mitophagy, and biogenesis in cachectic muscle. The potential for either muscle inactivity or exercise to alter mitochondrial dysfunction during cancer cachexia will also be discussed. PMID:28785374

  2. TAK1 regulates skeletal muscle mass and mitochondrial function

    Science.gov (United States)

    Hindi, Sajedah M.; Sato, Shuichi; Xiong, Guangyan; Bohnert, Kyle R.; Gibb, Andrew A.; Gallot, Yann S.; McMillan, Joseph D.; Hill, Bradford G.

    2018-01-01

    Skeletal muscle mass is regulated by a complex array of signaling pathways. TGF-β–activated kinase 1 (TAK1) is an important signaling protein, which regulates context-dependent activation of multiple intracellular pathways. However, the role of TAK1 in the regulation of skeletal muscle mass remains unknown. Here, we report that inducible inactivation of TAK1 causes severe muscle wasting, leading to kyphosis, in both young and adult mice.. Inactivation of TAK1 inhibits protein synthesis and induces proteolysis, potentially through upregulating the activity of the ubiquitin-proteasome system and autophagy. Phosphorylation and enzymatic activity of AMPK are increased, whereas levels of phosphorylated mTOR and p38 MAPK are diminished upon inducible inactivation of TAK1 in skeletal muscle. In addition, targeted inactivation of TAK1 leads to the accumulation of dysfunctional mitochondria and oxidative stress in skeletal muscle of adult mice. Inhibition of TAK1 does not attenuate denervation-induced muscle wasting in adult mice. Finally, TAK1 activity is highly upregulated during overload-induced skeletal muscle growth, and inactivation of TAK1 prevents myofiber hypertrophy in response to functional overload. Overall, our study demonstrates that TAK1 is a key regulator of skeletal muscle mass and oxidative metabolism. PMID:29415881

  3. Adenosine formation in contracting primary rat skeletal muscle cells and endothelial cells in culture

    DEFF Research Database (Denmark)

    Hellsten, Ylva; Frandsen, Ulrik

    1997-01-01

    1. The present study examined the capacity for adenosine formation, uptake and metabolism in contracting primary rat muscle cells and in microvascular endothelial cells in culture. 2. Strong and moderate electrical simulation of skeletal muscle cells led to a significantly greater increase....... 3. Addition of microvascular endothelial cells to the cultured skeletal muscle cells enhanced the contraction-induced accumulation of extracellular adenosine (P Skeletal muscle cells were...... in the extracellular adenosine concentration (421 +/- 91 and 235 +/- 30 nmol (g protein)-1, respectively; P muscle cells (161 +/- 20 nmol (g protein)-1). The ATP concentration was lower (18%; P contracted, but not in the moderately contracted muscle cells...

  4. Imbalance in SOD/CAT activities in rat skeletal muscles submitted to treadmill training exercise.

    Science.gov (United States)

    Pinho, Ricardo A; Andrades, Michael E; Oliveira, Marcos R; Pirola, Aline C; Zago, Morgana S; Silveira, Paulo C L; Dal-Pizzol, Felipe; Moreira, José Cláudio F

    2006-10-01

    The association between physical exercise and oxidative damage in the skeletal musculature has been the focus of many studies in literature, but the balance between superoxide dismutase and catalase activities and its relation to oxidative damage is not well established. Thus, the aim of the present study was to investigate the association between regular treadmill physical exercise, oxidative damage and antioxidant defenses in skeletal muscle of rats. Fifteen male Wistar rats (8-12 months) were randomly separated into two groups (trained n=9 and untrained n=6). Trained rats were treadmill-trained for 12 weeks in progressive exercise (velocity, time, and inclination). Training program consisted in a progressive exercise (10 m/min without inclination for 10 min/day). After 1 week the speed, time and inclination were gradually increased until 17 m/min at 10% for 50 min/day. After the training period animals were killed, and gastrocnemius and quadriceps were surgically removed to the determination of biochemical parameters. Lipid peroxidation, protein oxidative damage, catalase, superoxide dismutase and citrate synthase activities, and muscular glycogen content were measured in the isolated muscles. We demonstrated that there is a different modulation of CAT and SOD in skeletal muscle in trained rats when compared to untrained rats (increased SOD/CAT ratio). TBARS levels were significantly decreased and, in contrast, a significant increase in protein carbonylation was observed. These results suggest a non-described adaptation of skeletal muscle against exercise-induced oxidative stress.

  5. Gender-Dimorphic Regulation of Skeletal Muscle Proteins in Streptozotocin-Induced Diabetic Rats

    Directory of Open Access Journals (Sweden)

    Minji Choi

    2013-03-01

    Full Text Available Background: Despite the fact that sexual differences increase diabetic risk and contribute to the need for gender-specific care, there remain contradictory results as to whether or not sexual dimorphism increases susceptibility to the development of type 1 diabetes mellitus. Methods: To examine gender-dimorphic regulation of skeletal muscle proteins between healthy control and STZ-induced diabetic rats of both genders, we performed differential proteome analysis using two-dimensional electrophoresis combined with mass spectrometry. Results: Animal experiments revealed that STZ treatment rendered female rats more susceptible to induction of diabetes than their male littermates with significantly lower plasma insulin levels due to hormonal regulation. Proteomic analysis of skeletal muscle identified a total of 21 proteins showing gender-dimorphic differential expression patterns between healthy controls and diabetic rats. Most interestingly, gender-specific proteome comparison showed that male and female rats displayed differential regulation of proteins involved in muscle contraction, carbohydrate, and lipid metabolism, as well as oxidative phosphorylation and cellular stress. Conclusion: The current proteomic study revealed that impaired protein regulation was more prominent in the muscle tissue of female diabetic rats, which were more susceptible to STZ-induced diabetes. We expect that the present proteomic data can provide valuable information for evidence-based gender-specific treatment of diabetes.

  6. The expression of NFATc1 in adult rat skeletal muscle fibres.

    Science.gov (United States)

    Mutungi, Gabriel

    2008-03-01

    Although numerous studies have recently implicated the calcineurin-nuclear factor of activated T-cells (Cn-NFAT) signalling pathway in the regulation of activity-dependent fibre type switching in adult mammalian skeletal muscles, little is known about the endogenous expression of NFAT proteins in the various fibre types present in these muscles. In this study, the immunolocalization of NFATc1 (also known as NFATc or NFAT2) in the extensor digitorum longus (EDL; a mainly fast-twitch muscle) and the soleus (a predominantly slow-twitch muscle) muscles of adult ( approximately 90-day-old) Wistar rats was investigated. The results show that NFATc1 is expressed only in oxidative fibres (i.e. type I and type IIA fibres) that stain intensely for succinate dehydrogenase activity irrespective of whether they are from the fast- or slow-twitch muscle. Thus, 99 +/- 4% (n = 7 rats) of the muscle fibres in the soleus and 42 +/- 2% (n = 7 rats) of those in the EDL expressed NFATc1. In the soleus muscle fibres, NFATc1 was localized mainly in the fibre nuclei, whereas in the EDL fibres it was localized in both the cytoplasm and the nuclei. However, no difference in its localization was observed between type I and type IIA fibres in both muscles. Western blot experiments showed that the soleus expressed more NFATc1 proteins than the EDL. From these results, we suggest that NFATc1 controls the number and distribution of both type I and type IIA fibres, as well as the oxidative capacity of adult mammalian skeletal muscles.

  7. Skeletal Muscle and Lymphocyte Mitochondrial Dysfunctions in Septic Shock Trigger ICU-Acquired Weakness and Sepsis-Induced Immunoparalysis

    Directory of Open Access Journals (Sweden)

    Quentin Maestraggi

    2017-01-01

    Full Text Available Fundamental events driving the pathological processes of septic shock-induced multiorgan failure (MOF at the cellular and subcellular levels remain debated. Emerging data implicate mitochondrial dysfunction as a critical factor in the pathogenesis of sepsis-associated MOF. If macrocirculatory and microcirculatory dysfunctions undoubtedly participate in organ dysfunction at the early stage of septic shock, an intrinsic bioenergetic failure, sometimes called “cytopathic hypoxia,” perpetuates cellular dysfunction. Short-term failure of vital organs immediately threatens patient survival but long-term recovery is also severely hindered by persistent dysfunction of organs traditionally described as nonvital, such as skeletal muscle and peripheral blood mononuclear cells (PBMCs. In this review, we will stress how and why a persistent mitochondrial dysfunction in skeletal muscles and PBMC could impair survival in patients who overcome the first acute phase of their septic episode. First, muscle wasting protracts weaning from mechanical ventilation, increases the risk of mechanical ventilator-associated pneumonia, and creates a state of ICU-acquired muscle weakness, compelling the patient to bed. Second, failure of the immune system (“immunoparalysis” translates into its inability to clear infectious foci and predisposes the patient to recurrent nosocomial infections. We will finally emphasize how mitochondrial-targeted therapies could represent a realistic strategy to promote long-term recovery after sepsis.

  8. ATP-induced changes in rat skeletal muscle contractility.

    Science.gov (United States)

    Gabdrakhmanov, A I; Khayrullin, A E; Grishin, C H; Ziganshin, A U

    2015-01-01

    considered as typical effects of ATP and other purines on skeletal muscles and could not be extrapolated to all warm-blooded animals. Furthermore the role of ATP and its derivatives in the accumulation of vertebrate muscular effort has not been investigated.It is known that in physiological conditions vertebrates may mobilize only up to a third of the maximum muscle force. Why the two-thirds of muscular strength are not used normally but may be used at stress, remains unknown.It is known that the body's adaptive response to stress is a change in the activity of the endocrine system. The leading role in this is given to catechol amines and glucocorticoids, mobilized in significant quantities in blood under stress.We have found previously that incubation of frog sartorius muscle with hydrocortisone resulted in a decrease of contraction amplitude. However, when hydrocortisone was used in combination with ATP, its inhibitory effect on contractile responses disappeared. It is interesting that hydrocortisone had no effect on the inhibitory effect of adenosine. In the following experiments, assessing the effect of hydrocortisone on rat soleus muscle, it was established that hydrocortisone and purines had similar inhibitory effect. When ATP and hydrocortisone were given together the same oppression occurred. To study the effects of ATP and adenosine on contraction parameters of rat skeletal muscle and assess the impact of the catechol amines on these processes. Contractions of rat soleus muscles were recorded isometrically by mechanical sensor Linton FSG-01 (UK) according to standard procedures. The average of muscle parameters received within 30 seconds (30 responses) was treated as one result. Amplitude and time characteristics of the curve reductions were estimated. During all experiments standard Krebs solution flowed through the bath continuously to which agents were added at necessary concentrations. All experimental animals were maintained and prepared for dissection under

  9. Activation of estrogen response elements is mediated both via estrogen and muscle contractions in rat skeletal muscle myotubes

    DEFF Research Database (Denmark)

    Wiik, A.; Hellsten, Ylva; Berthelson, P.

    2009-01-01

    is ER independent. The muscle contraction-induced transactivation of ERE and increase in ERbeta mRNA were instead found to be MAP kinase (MAPK) dependent. This study demonstrates for the first time that muscle contractions have a similar functional effect as estrogen in skeletal muscle myotubes, causing......The aim of the present study was to investigate the activation of estrogen response elements (EREs) by estrogen and muscle contractions in rat myotubes in culture and to assess whether the activation is dependent on the estrogen receptors (ERs). In addition, the effect of estrogen and contraction...... on the mRNA levels of ERalpha and ERbeta was studied to determine the functional consequence of the transactivation. Myoblasts were isolated from rat skeletal muscle and transfected with a vector consisting of sequences of EREs coupled to the gene for luciferase. The transfected myoblasts were...

  10. Pioglitazone enhances mitochondrial biogenesis and ribosomal protein biosynthesis in skeletal muscle in polycystic ovary syndrome

    DEFF Research Database (Denmark)

    Skov, Vibe; Glintborg, Dorte; Knudsen, Steen

    2008-01-01

    indicate that pioglitazone therapy restores insulin sensitivity, in part, by a coordinated upregulation of genes involved in mitochondrial OXPHOS and ribosomal protein biosynthesis in muscle in PCOS. These transcriptional effects of pioglitazone may contribute to prevent the onset of type 2 diabetes...... by changes in the transcriptional profile of muscle favoring insulin sensitivity. Using Affymetrix microarrays, we examined the effect of pioglitazone (30 mg/day for 16 weeks) on gene expression in skeletal muscle of 10 obese women with PCOS metabolically characterized by a euglycemic-hyperinsulinemic clamp...... Annotator and Pathway Profiler (GenMAPP 2.1) and Gene Set Enrichment Analysis (GSEA 2.0.1) revealed a significant upregulation of genes representing mitochondrial oxidative phosphorylation (OXPHOS), ribosomal proteins, mRNA processing reactome, translation factors, and proteasome degradation in PCOS after...

  11. Neuromuscular junction formation between human stem-cell-derived motoneurons and rat skeletal muscle in a defined system.

    Science.gov (United States)

    Guo, Xiufang; Das, Mainak; Rumsey, John; Gonzalez, Mercedes; Stancescu, Maria; Hickman, James

    2010-12-01

    To date, the coculture of motoneurons (MNs) and skeletal muscle in a defined in vitro system has only been described in one study and that was between rat MNs and rat skeletal muscle. No in vitro studies have demonstrated human MN to rat muscle synapse formation, although numerous studies have attempted to implant human stem cells into rat models to determine if they could be of therapeutic use in disease or spinal injury models, although with little evidence of neuromuscular junction (NMJ) formation. In this report, MNs differentiated from human spinal cord stem cells, together with rat skeletal myotubes, were used to build a coculture system to demonstrate that NMJ formation between human MNs and rat skeletal muscles is possible. The culture was characterized by morphology, immunocytochemistry, and electrophysiology, while NMJ formation was demonstrated by immunocytochemistry and videography. This defined system provides a highly controlled reproducible model for studying the formation, regulation, maintenance, and repair of NMJs. The in vitro coculture system developed here will be an important model system to study NMJ development, the physiological and functional mechanism of synaptic transmission, and NMJ- or synapse-related disorders such as amyotrophic lateral sclerosis, as well as for drug screening and therapy design.

  12. Effects of a standardized Panax ginseng extract on the skeletal muscle of the rat: a comparative study in animals at rest and under exercise.

    Science.gov (United States)

    Ferrando, A; Vila, L; Voces, J A; Cabral, A C; Alvarez, A I; Prieto, J G

    1999-04-01

    The effect of standardized Panax ginseng extract G115 on enzymatic activities, myotypological composition, capillaries and mitochondrial content was studied in the skeletal muscle of male rats Wistar. Simultaneously to the G115 administration the rats performed exercise. The animals were divided into 4 groups. The dose of the ginseng extract G115 was 50 mg/kg. The length of the experimental period was 12 weeks. After 24 hours of inactivity the muscles of the hindlimb were extracted. With regard to the enzymatic activities of the citrate synthase (CS) and lactate dehydrogenase (LDH), CS increases with exercise, while the LDH undergoes no major variations, either due to the exercise or the treatment. Treatment with G115 increases the capillary density and the mitochondrial content of the red gastrocnemius muscle. The results suggest that prolonged treatment with G115 increases the capillary density and the oxidative capacity of the muscles with greater aerobic potential in a manner similar to the performance of physical exercise. When exercise and treatment are combined, the effects that are obtained separately are not potentiated.

  13. Gestational diabetes is characterized by reduced mitochondrial protein expression and altered calcium signaling proteins in skeletal muscle.

    Directory of Open Access Journals (Sweden)

    Kristen E Boyle

    Full Text Available The rising prevalence of gestational diabetes mellitus (GDM affects up to 18% of pregnant women with immediate and long-term metabolic consequences for both mother and infant. Abnormal glucose uptake and lipid oxidation are hallmark features of GDM prompting us to use an exploratory proteomics approach to investigate the cellular mechanisms underlying differences in skeletal muscle metabolism between obese pregnant women with GDM (OGDM and obese pregnant women with normal glucose tolerance (ONGT. Functional validation was performed in a second cohort of obese OGDM and ONGT pregnant women. Quantitative proteomic analysis in rectus abdominus skeletal muscle tissue collected at delivery revealed reduced protein content of mitochondrial complex I (C-I subunits (NDUFS3, NDUFV2 and altered content of proteins involved in calcium homeostasis/signaling (calcineurin A, α1-syntrophin, annexin A4 in OGDM (n = 6 vs. ONGT (n = 6. Follow-up analyses showed reduced enzymatic activity of mitochondrial complexes C-I, C-III, and C-IV (-60-75% in the OGDM (n = 8 compared with ONGT (n = 10 subjects, though no differences were observed for mitochondrial complex protein content. Upstream regulators of mitochondrial biogenesis and oxidative phosphorylation were not different between groups. However, AMPK phosphorylation was dramatically reduced by 75% in the OGDM women. These data suggest that GDM is associated with reduced skeletal muscle oxidative phosphorylation and disordered calcium homeostasis. These relationships deserve further attention as they may represent novel risk factors for development of GDM and may have implications on the effectiveness of physical activity interventions on both treatment strategies for GDM and for prevention of type 2 diabetes postpartum.

  14. Pathogenesis of Insulin Resistance in Skeletal Muscle

    Directory of Open Access Journals (Sweden)

    Muhammad A. Abdul-Ghani

    2010-01-01

    Full Text Available Insulin resistance in skeletal muscle is manifested by decreased insulin-stimulated glucose uptake and results from impaired insulin signaling and multiple post-receptor intracellular defects including impaired glucose transport, glucose phosphorylation, and reduced glucose oxidation and glycogen synthesis. Insulin resistance is a core defect in type 2 diabetes, it is also associated with obesity and the metabolic syndrome. Dysregulation of fatty acid metabolism plays a pivotal role in the pathogenesis of insulin resistance in skeletal muscle. Recent studies have reported a mitochondrial defect in oxidative phosphorylation in skeletal muscle in variety of insulin resistant states. In this review, we summarize the cellular and molecular defects that contribute to the development of insulin resistance in skeletal muscle.

  15. Insulin Resistance Is Not Associated with an Impaired Mitochondrial Function in Contracting Gastrocnemius Muscle of Goto-Kakizaki Diabetic Rats In Vivo.

    Directory of Open Access Journals (Sweden)

    Michael Macia

    Full Text Available Insulin resistance, altered lipid metabolism and mitochondrial dysfunction in skeletal muscle would play a major role in type 2 diabetes mellitus (T2DM development, but the causal relationships between these events remain conflicting. To clarify this issue, gastrocnemius muscle function and energetics were investigated throughout a multidisciplinary approach combining in vivo and in vitro measurements in Goto-Kakizaki (GK rats, a non-obese T2DM model developing peripheral insulin resistant without abnormal level of plasma non-esterified fatty acids (NEFA. Wistar rats were used as controls. Mechanical performance and energy metabolism were assessed strictly non-invasively using magnetic resonance (MR imaging and 31-phosphorus MR spectroscopy (31P-MRS. Compared with control group, plasma insulin and glucose were respectively lower and higher in GK rats, but plasma NEFA level was normal. In resting GK muscle, phosphocreatine content was reduced whereas glucose content and intracellular pH were both higher. However, there were not differences between both groups for basal oxidative ATP synthesis rate, citrate synthase activity, and intramyocellular contents for lipids, glycogen, ATP and ADP (an important in vivo mitochondrial regulator. During a standardized fatiguing protocol (6 min of maximal repeated isometric contractions electrically induced at a frequency of 1.7 Hz, mechanical performance and glycolytic ATP production rate were reduced in diabetic animals whereas oxidative ATP production rate, maximal mitochondrial capacity and ATP cost of contraction were not changed. These findings provide in vivo evidence that insulin resistance is not caused by an impairment of mitochondrial function in this diabetic model.

  16. Intrauterine growth retardation increases the susceptibility of pigs to high-fat diet-induced mitochondrial dysfunction in skeletal muscle.

    Directory of Open Access Journals (Sweden)

    Jingbo Liu

    Full Text Available It has been recognized that there is a relationship between prenatal growth restriction and the development of metabolic-related diseases in later life, a process involved in mitochondrial dysfunction. In addition, intrauterine growth retardation (IUGR increases the susceptibility of offspring to high-fat (HF diet-induced metabolic syndrome. Recent findings suggested that HF feeding decreased mitochondrial oxidative capacity and impaired mitochondrial function in skeletal muscle. Therefore, we hypothesized that the long-term consequences of IUGR on mitochondrial biogenesis and function make the offspring more susceptible to HF diet-induced mitochondrial dysfunction. Normal birth weight (NBW, and IUGR pigs were allotted to control or HF diet in a completely randomized design, individually. After 4 weeks of feeding, growth performance and molecular pathways related to mitochondrial function were determined. The results showed that IUGR decreased growth performance and plasma insulin concentrations. In offspring fed a HF diet, IUGR was associated with enhanced plasma leptin levels, increased concentrations of triglyceride and malondialdehyde (MDA, and reduced glycogen and ATP contents in skeletal muscle. High fat diet-fed IUGR offspring exhibited decreased activities of lactate dehydrogenase (LDH and glucose-6-phosphate dehydrogenase (G6PD. These alterations in metabolic traits of IUGR pigs were accompanied by impaired mitochondrial respiration function, reduced mitochondrial DNA (mtDNA contents, and down-regulated mRNA expression levels of genes responsible for mitochondrial biogenesis and function. In conclusion, our results suggest that IUGR make the offspring more susceptible to HF diet-induced mitochondrial dysfunction.

  17. Intrauterine Growth Retardation Increases the Susceptibility of Pigs to High-Fat Diet-Induced Mitochondrial Dysfunction in Skeletal Muscle

    Science.gov (United States)

    Liu, Jingbo; Chen, Daiwen; Yao, Ying; Yu, Bing; Mao, Xiangbing; He, Jun; Huang, Zhiqing; Zheng, Ping

    2012-01-01

    It has been recognized that there is a relationship between prenatal growth restriction and the development of metabolic-related diseases in later life, a process involved in mitochondrial dysfunction. In addition, intrauterine growth retardation (IUGR) increases the susceptibility of offspring to high-fat (HF) diet-induced metabolic syndrome. Recent findings suggested that HF feeding decreased mitochondrial oxidative capacity and impaired mitochondrial function in skeletal muscle. Therefore, we hypothesized that the long-term consequences of IUGR on mitochondrial biogenesis and function make the offspring more susceptible to HF diet-induced mitochondrial dysfunction. Normal birth weight (NBW), and IUGR pigs were allotted to control or HF diet in a completely randomized design, individually. After 4 weeks of feeding, growth performance and molecular pathways related to mitochondrial function were determined. The results showed that IUGR decreased growth performance and plasma insulin concentrations. In offspring fed a HF diet, IUGR was associated with enhanced plasma leptin levels, increased concentrations of triglyceride and malondialdehyde (MDA), and reduced glycogen and ATP contents in skeletal muscle. High fat diet-fed IUGR offspring exhibited decreased activities of lactate dehydrogenase (LDH) and glucose-6-phosphate dehydrogenase (G6PD). These alterations in metabolic traits of IUGR pigs were accompanied by impaired mitochondrial respiration function, reduced mitochondrial DNA (mtDNA) contents, and down-regulated mRNA expression levels of genes responsible for mitochondrial biogenesis and function. In conclusion, our results suggest that IUGR make the offspring more susceptible to HF diet-induced mitochondrial dysfunction. PMID:22523560

  18. Inhibitors of the proteasome reduce the accelerated proteolysis in atrophying rat skeletal muscles.

    OpenAIRE

    Tawa, N E; Odessey, R; Goldberg, A L

    1997-01-01

    Several observations have suggested that the enhanced proteolysis and atrophy of skeletal muscle in various pathological states is due primarily to activation of the ubiquitin-proteasome pathway. To test this idea, we investigated whether peptide aldehyde inhibitors of the proteasome, N-acetyl-leucyl-leucyl-norleucinal (LLN), or the more potent CBZ-leucyl-leucyl-leucinal (MG132) suppressed proteolysis in incubated rat skeletal muscles. These agents (e.g., MG132 at 10 microM) inhibited nonlyso...

  19. Alterations to mitochondrial fatty-acid use in skeletal muscle after chronic exposure to hypoxia depend on metabolic phenotype.

    Science.gov (United States)

    Malgoyre, Alexandra; Chabert, Clovis; Tonini, Julia; Koulmann, Nathalie; Bigard, Xavier; Sanchez, Hervé

    2017-03-01

    We investigated the effects of chronic hypoxia on the maximal use of and sensitivity of mitochondria to different substrates in rat slow-oxidative (soleus, SOL) and fast-glycolytic (extensor digitorum longus, EDL) muscles. We studied mitochondrial respiration in situ in permeabilized myofibers, using pyruvate, octanoate, palmitoyl-carnitine (PC), or palmitoyl-coenzyme A (PCoA). The hypophagia induced by hypoxia may also alter metabolism. Therefore, we used a group of pair-fed rats (reproducing the same caloric restriction, as observed in hypoxic animals), in addition to the normoxic control fed ad libitum. The resting respiratory exchange ratio decreased after 21 days of exposure to hypobaric hypoxia (simulated elevation of 5,500 m). The respiration supported by pyruvate and octanoate were unaffected. In contrast, the maximal oxidative respiratory rate for PCoA, the transport of which depends on carnitine palmitoyltransferase 1 (CPT-1), decreased in the rapid-glycolytic EDL and increased in the slow-oxidative SOL, although hypoxia improved affinity for this substrate in both muscle types. PC and PCoA were oxidized similarly in normoxic EDL, whereas chronic hypoxia limited transport at the CPT-1 step in this muscle. The effects of hypoxia were mediated by caloric restriction in the SOL and by hypoxia itself in the EDL. We conclude that improvements in mitochondrial affinity for PCoA, a physiological long-chain fatty acid, would facilitate fatty-acid use at rest after chronic hypoxia independently of quantitative alterations of mitochondria. Conversely, decreasing the maximal oxidation of PCoA in fast-glycolytic muscles would limit fatty-acid use during exercise. NEW & NOTEWORTHY Affinity for low concentrations of long-chain fatty acids (LCFA) in mitochondria skeletal muscles increases after chronic hypoxia. Combined with a lower respiratory exchange ratio, this suggests facility for fatty acid utilization at rest. This fuel preference is related to caloric

  20. Site of mitochondrial reactive oxygen species production in skeletal muscle of chronic obstructive pulmonary disease and its relationship with exercise oxidative stress.

    Science.gov (United States)

    Puente-Maestu, Luis; Tejedor, Alberto; Lázaro, Alberto; de Miguel, Javier; Alvarez-Sala, Luis; González-Aragoneses, Federico; Simón, Carlos; Agustí, Alvar

    2012-09-01

    Exercise triggers skeletal muscle oxidative stress in patients with chronic obstructive pulmonary disease (COPD). The objective of this research was to study the specific sites of reactive oxygen species (ROS) production in mitochondria isolated from skeletal muscle of patients with COPD and its relationship with local oxidative stress induced by exercise. Vastus lateralis biopsies were obtained in 16 patients with COPD (66 ± 10 yr; FEV(1), 54 ± 12% ref) and in 14 control subjects with normal lung function who required surgery because of lung cancer (65 ± 7 yr; FEV(1), 91 ± 14% ref) at rest and after exercise. In these biopsies we isolated mitochondria and mitochondrial membrane fragments and determined in vitro mitochondrial oxygen consumption (Mit$$\\stackrel{.}{\\hbox{ V }}$$o(2)) and ROS production before and after inhibition of complex I (rotenone), complex II (stigmatellin), and complex III (antimycin-A). We related the in vitro ROS production during state 3 respiration), which mostly corresponds to the mitochondria respiratory state during exercise, with skeletal muscle oxidative stress after exercise, as measured by thiobarbituric acid reactive substances.State 3 Mit$$\\stackrel{.}{\\hbox{ V }}$$o(2) was similar in patients with COPD and control subjects (191 ± 27 versus 229 ± 46 nmol/min/mg; P = 0.058), whereas H(2)O(2) production was higher in the former (147 ± 39 versus 51 ± 8 pmol/mg/h; P release by mitochondria in patients with COPD and in control subjects. The mitochondrial production of H(2)O(2) in state 3 respiration was related (r = 0.69; P < 0.001) to postexercise muscle thiobarbituric acid reactive substance levels. Our results show that complex III is the main site of the enhanced mitochondrial H(2)O(2) production that occurs in skeletal muscle of patients with COPD, and the latter appears to contribute to muscle oxidative damage.

  1. The role of weight loss and exercise in correcting skeletal muscle mitochondrial abnormalities in obesity, diabetes and aging.

    Science.gov (United States)

    Toledo, Frederico G S; Goodpaster, Bret H

    2013-10-15

    Mitochondria within skeletal muscle have been implicated in insulin resistance of obesity and type 2 diabetes mellitus as well as impaired muscle function with normal aging. Evaluating the potential of interventions to improve mitochondria is clearly relevant to the prevention or treatment of metabolic diseases and age-related dysfunction. This review provides an overview and critical evaluation of the effects of weight loss and exercise interventions on skeletal muscle mitochondria, along with implications for insulin resistance, obesity, type 2 diabetes and aging. The available literature strongly suggests that the lower mitochondrial capacity associated with obesity, type 2 diabetes and aging is not an irreversible lesion. However, weight loss does not appear to affect this response, even when the weight loss is extreme. In contrast, increasing physical activity improves mitochondrial content and perhaps the function of individual mitochondrion. Despite the consistent effect of exercise to improve mitochondrial capacity, studies mechanistically linking mitochondria to insulin resistance, reductions in intramyocellular lipid or improvement in muscle function remain inconclusive. In summary, studies of diet and exercise training have advanced our understanding of the link between mitochondrial oxidative capacity and insulin resistance in obesity, type 2 diabetes and aging. Nevertheless, additional inquiry is necessary to establish the significance and clinical relevance of those perturbations, which could lead to targeted therapies for a myriad of conditions and diseases involving mitochondria. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  2. Nitric oxide and Na,K-ATPase activity in rat skeletal muscle

    DEFF Research Database (Denmark)

    Juel, Carsten

    2016-01-01

    Aim: It has been suggested that nitric oxide (NO) stimulates the Na,K-ATPase in cardiac myocytes. Therefore, the aims of this study were to investigate whether NO increases Na,K-ATPase activity in skeletal muscle and, if that is the case, to identify the underlying mechanism. Method: The study used...... isolated rat muscle, muscle homogenates and purified membranes as model systems. Na,K-ATPase activity was quantified from phosphate release due to ATP hydrolysis. Results: Exposure to the NO donor spermine NONOate (10 μm) increased the maximal Na,K-ATPase activity by 27% in isolated glycolytic muscles...... activity was depressed by oxidized glutathione. Conclusion: NO and cGMP stimulate the Na,K-ATPase in glycolytic skeletal muscle. Direct S-nitrosylation and interference with S-glutathionylation seem to be excluded. In addition, phosphorylation of phospholemman at serine 68 is not involved. Most likely...

  3. Low-intensity aerobic exercise training: inhibition of skeletal muscle atrophy in high-fat-diet-induced ovariectomized rats.

    Science.gov (United States)

    Kim, Hye Jin; Lee, Won Jun

    2017-09-30

    Postmenopausal women are highly susceptible to diseases, such as obesity, type 2 diabetes, osteoporosis, or skeletal muscle atrophy and many people recognize the need for regular physical activity. Aerobic exercise training is known to improve the oxidative capacity and insulin sensitivity of skeletal muscles. This study aimed to investigate the role of low-intensity aerobic exercise training on skeletal muscle protein degradation or synthesis in the plantaris muscles of high-fat-fed ovariectomized rats. Ovariectomized female rats were divided into two groups: a high-fat diet-sedentary group (HFD), and a high-fat diet-aerobic exercise group (HFD+EX). The exercise group exercised aerobically on a treadmill 5 days/week for 8 weeks. The rats progressively ran 30 min/day at 15 m/min, up to 40 min/day at 18 m/min, 0% slope, in the last 4 weeks. Although aerobic exercise led to significantly increased AMP-activated protein kinase (AMPK) phosphorylation at Thr172, phosphorylation of the mammalian target of rapamycin (mTOR) substrate Thr389 S6K1 level did not decrease. Additionally, even though Akt activity did not increase at Ser473, the atrogin-1 level significantly decreased in the exercise group compared to the non-exercise group. Immunohistochemical staining revealed that high-fat-induced TSC2 protein expression was eliminated in response to aerobic exercise. These results suggest that aerobic exercise can inhibit skeletal muscle protein degradation, but it cannot increase protein synthesis in the plantaris muscle of high-fat-fed ovariectomized rats. Our findings have implications in understanding skeletal muscle mass maintenance with low intensity aerobic exercise in post-menopausal women. ©2017 The Korean Society for Exercise Nutrition

  4. Human skeletal muscle mitochondrial capacity.

    Science.gov (United States)

    Rasmussen, U F; Rasmussen, H N

    2000-04-01

    Under aerobic work, the oxygen consumption and major ATP production occur in the mitochondria and it is therefore a relevant question whether the in vivo rates can be accounted for by mitochondrial capacities measured in vitro. Mitochondria were isolated from human quadriceps muscle biopsies in yields of approximately 45%. The tissue content of total creatine, mitochondrial protein and different cytochromes was estimated. A number of activities were measured in functional assays of the mitochondria: pyruvate, ketoglutarate, glutamate and succinate dehydrogenases, palmitoyl-carnitine respiration, cytochrome oxidase, the respiratory chain and the ATP synthesis. The activities involved in carbohydrate oxidation could account for in vivo oxygen uptakes of 15-16 mmol O2 min-1 kg-1 or slightly above the value measured at maximal work rates in the knee-extensor model of Saltin and co-workers, i.e. without limitation from the cardiac output. This probably indicates that the maximal oxygen consumption of the muscle is limited by the mitochondrial capacities. The in vitro activities of fatty acid oxidation corresponded to only 39% of those of carbohydrate oxidation. The maximal rate of free energy production from aerobic metabolism of glycogen was calculated from the mitochondrial activities and estimates of the DeltaG or ATP hydrolysis and the efficiency of the actin-myosin reaction. The resultant value was 20 W kg-1 or approximately 70% of the maximal in vivo work rates of which 10-20% probably are sustained by the anaerobic ATP production. The lack of aerobic in vitro ATP synthesis might reflect termination of some critical interplay between cytoplasm and mitochondria.

  5. Increased skeletal muscle capillarization enhances insulin sensitivity

    DEFF Research Database (Denmark)

    Åkerström, Thorbjörn; Laub, Lasse; Vedel, Kenneth

    2014-01-01

    Increased skeletal muscle capillarization is associated with improved glucose tolerance and insulin sensitivity. However, a possible causal relationship has not previously been identified. We therefore investigated whether increased skeletal muscle capillarization increases insulin sensitivity....... Skeletal muscle specific angiogenesis was induced by adding the α1-adrenergic receptor antagonist Prazosin to the drinking water of Sprague Dawley rats (n=33) while 34 rats served as controls. Insulin sensitivity was measured ≥40 h after termination of the 3-week Prazosin treatment, which ensured...... that Prazosin was cleared from the blood stream. Whole-body insulin sensitivity was measured in conscious, unrestrained rats by hyperinsulinemic euglycemic clamp. Tissue specific insulin sensitivity was assessed by administration of 2-deoxy-[(3)H]-Glucose during the plateau phase of the clamp. Whole...

  6. Mitochondrial coupling and capacity of oxidative phosphorylation in skeletal muscle of Inuit and Caucasians in the arctic winter.

    Science.gov (United States)

    Gnaiger, E; Boushel, R; Søndergaard, H; Munch-Andersen, T; Damsgaard, R; Hagen, C; Díez-Sánchez, C; Ara, I; Wright-Paradis, C; Schrauwen, P; Hesselink, M; Calbet, J A L; Christiansen, M; Helge, J W; Saltin, B

    2015-12-01

    During evolution, mitochondrial DNA haplogroups of arctic populations may have been selected for lower coupling of mitochondrial respiration to ATP production in favor of higher heat production. We show that mitochondrial coupling in skeletal muscle of traditional and westernized Inuit habituating northern Greenland is identical to Danes of western Europe haplogroups. Biochemical coupling efficiency was preserved across variations in diet, muscle fiber type, and uncoupling protein-3 content. Mitochondrial phenotype displayed plasticity in relation to lifestyle and environment. Untrained Inuit and Danes had identical capacities to oxidize fat substrate in arm muscle, which increased in Danes during the 42 days of acclimation to exercise, approaching the higher level of the Inuit hunters. A common pattern emerges of mitochondrial acclimatization and evolutionary adaptation in humans at high latitude and high altitude where economy of locomotion may be optimized by preservation of biochemical coupling efficiency at modest mitochondrial density, when submaximum performance is uncoupled from VO2max and maximum capacities of oxidative phosphorylation. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  7. A DIGE proteomic analysis for high-intensity exercise-trained rat skeletal muscle.

    Science.gov (United States)

    Yamaguchi, Wataru; Fujimoto, Eri; Higuchi, Mitsuru; Tabata, Izumi

    2010-09-01

    Exercise training induces various adaptations in skeletal muscles. However, the mechanisms remain unclear. In this study, we conducted 2D-DIGE proteomic analysis, which has not yet been used for elucidating adaptations of skeletal muscle after high-intensity exercise training (HIT). For 5 days, rats performed HIT, which consisted of 14 20-s swimming exercise bouts carrying a weight (14% of the body weight), and 10-s pause between bouts. The 2D-DIGE analysis was conducted on epitrochlearis muscles excised 18 h after the final training exercise. Proteomic profiling revealed that out of 800 detected and matched spots, 13 proteins exhibited changed expression by HIT compared with sedentary rats. All proteins were identified by MALDI-TOF/MS. Furthermore, using western immunoblot analyses, significantly changed expressions of NDUFS1 and parvalbumin (PV) were validated in relation to HIT. In conclusion, the proteomic 2D-DIGE analysis following HIT-identified expressions of NDUFS1 and PV, previously unknown to have functions related to exercise-training adaptations.

  8. Long-term rates of mitochondrial protein synthesis are increased in mouse skeletal muscle with high-fat feeding regardless of insulin-sensitizing treatment.

    Science.gov (United States)

    Newsom, Sean A; Miller, Benjamin F; Hamilton, Karyn L; Ehrlicher, Sarah E; Stierwalt, Harrison D; Robinson, Matthew M

    2017-11-01

    Skeletal muscle mitochondrial protein synthesis is regulated in part by insulin. The development of insulin resistance with diet-induced obesity may therefore contribute to impairments to protein synthesis and decreased mitochondrial respiration. Yet the impact of diet-induced obesity and insulin resistance on mitochondrial energetics is controversial, with reports varying from decreases to increases in mitochondrial respiration. We investigated the impact of changes in insulin sensitivity on long-term rates of mitochondrial protein synthesis as a mechanism for changes to mitochondrial respiration in skeletal muscle. Insulin resistance was induced in C57BL/6J mice using 4 wk of a high-fat compared with a low-fat diet. For 8 additional weeks, diets were enriched with pioglitazone to restore insulin sensitivity compared with nonenriched control low-fat or high-fat diets. Skeletal muscle mitochondrial protein synthesis was measured using deuterium oxide labeling during weeks 10-12 High-resolution respirometry was performed using palmitoyl-l-carnitine, glutamate+malate, and glutamate+malate+succinate as substrates for mitochondria isolated from quadriceps. Mitochondrial protein synthesis and palmitoyl- l-carnitine oxidation were increased in mice consuming a high-fat diet, regardless of differences in insulin sensitivity with pioglitazone treatment. There was no effect of diet or pioglitazone treatment on ADP-stimulated respiration or H 2 O 2 emission using glutamate+malate or glutamate+malate+succinate. The results demonstrate no impairments to mitochondrial protein synthesis or respiration following induction of insulin resistance. Instead, mitochondrial protein synthesis was increased with a high-fat diet and may contribute to remodeling of the mitochondria to increase lipid oxidation capacity. Mitochondrial adaptations with a high-fat diet appear driven by nutrient availability, not intrinsic defects that contribute to insulin resistance. Copyright © 2017 the

  9.  Age-related changes of skeletal muscles: physiology, pathology and regeneration

    Directory of Open Access Journals (Sweden)

    Aleksandra Ławniczak

    2012-06-01

    Full Text Available  This review provides a short presentation of the aging-related changes of human skeletal muscles. The aging process is associated with the loss of skeletal muscle mass (sarcopenia and strength. This results from fibre atrophy and apoptosis, decreased regeneration capacity, mitochondrial dysfunction, gradual reduction of the number of spinal cord motor neurons, and local and systemic metabolic and hormonal alterations. The latter involve age-related decrease of the expression and activity of some mitochondrial and cytoplasmic enzymes, triacylglycerols and lipofuscin accumulation inside muscle fibres, increased proteolytic activity, insulin resistance and decreased serum growth hormone and IGF-1 concentrations. Aging of the skeletal muscles is also associated with a decreased number of satellite cells and their proliferative activity. The age-related reduction of skeletal muscle mass and function may be partially prevented by dietary restriction and systematic physical exercises.

  10. Single molecular image of cytosolic free Ca2+ of skeletal muscle cells in rats pre- and post-exercise-induced fatigue

    Science.gov (United States)

    Liu, Yi; Zhang, Heming; Zhao, Yanping; Liu, Zhiming

    2009-08-01

    A growing body of literature indicated the cytosolic free Ca2+ concentration of skeletal muscle cells changes significantly during exercise-induced fatigue. But it is confusing whether cytosolic free Ca2+ concentration increase or decrease. Furthermore, current researches mainly adopt muscle tissue homogenate as experiment material, but the studies based on cellular and subcellular level is seldom. This study is aimed to establish rat skeletal muscle cell model of exercise-induced fatigue, and confirm the change of cytosolic free Ca2+ concentration of skeletal muscle cells in rats preand post- exercise-induced fatigue. In this research, six male Wistar rats were randomly divided into two groups: control group (n=3) and exercise-induced fatigue group (n=3). The former group were allowed to freely move and the latter were forced to loaded swimming to exhaustive. Three days later, all the rats were sacrificed, the muscle tissue from the same site of skeletal muscle were taken out and digested to cells. After primary culture of the two kinds of skeletal muscle cells from tissue, a fluorescent dye-Fluo-3 AM was used to label the cytosolic free Ca2+. The fluorescent of Ca2+ was recorded by confocal laser scanning microscopy. The results indicated that, the Ca2+ fluorescence intensity of cells from the rat of exercise-induced fatigue group was significantly higher than those in control group. In conclusion, cytosolic free Ca2+ concentration of skeletal muscle cells has a close relation with exercise-induced fatigue, and the increase of cytosolic free Ca2+ concentration may be one of the important factors of exercise-induced fatigue.

  11. Increased Muscular 5α-Dihydrotestosterone in Response to Resistance Training Relates to Skeletal Muscle Mass and Glucose Metabolism in Type 2 Diabetic Rats.

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    Naoki Horii

    Full Text Available Regular resistance exercise induces skeletal muscle hypertrophy and improvement of glycemic control in type 2 diabetes patients. Administration of dehydroepiandrosterone (DHEA, a sex steroid hormone precursor, increases 5α-dihydrotestosterone (DHT synthesis and is associated with improvements in fasting blood glucose level and skeletal muscle hypertrophy. Therefore, the aim of this study was to investigate whether increase in muscle DHT levels, induced by chronic resistance exercise, can contribute to skeletal muscle hypertrophy and concomitant improvement of muscular glucose metabolism in type 2 diabetic rats. Male 20-week-old type 2 diabetic rats (OLETF were randomly divided into 3 groups: sedentary control, resistance training (3 times a week on alternate days for 8 weeks, or resistance training with continuous infusion of a 5α-reductase inhibitor (n = 8 each group. Age-matched, healthy nondiabetic Long-Evans Tokushima Otsuka (LETO rats (n = 8 were used as controls. The results indicated that OLETF rats showed significant decrease in muscular DHEA, free testosterone, DHT levels, and protein expression of steroidogenic enzymes, with loss of skeletal muscle mass and hyperglycemia, compared to that of LETO rats. However, 8-week resistance training in OLETF rats significantly increased the levels of muscle sex steroid hormones and protein expression of steroidogenic enzymes with a concomitant increase in skeletal muscle mass, improved fasting glucose level, and insulin sensitivity index. Moreover, resistance training accelerated glucose transporter-4 (GLUT-4 translocation and protein kinase B and C-ζ/λ phosphorylation. Administering the 5α-reductase inhibitor in resistance-trained OLETF rats resulted in suppression of the exercise-induced effects on skeletal muscle mass, fasting glucose level, insulin sensitivity index, and GLUT-4 signaling, with a decline in muscular DHT levels. These findings suggest that resistance training

  12. Autophagic signaling and proteolytic enzyme activity in cardiac and skeletal muscle of spontaneously hypertensive rats following chronic aerobic exercise.

    Directory of Open Access Journals (Sweden)

    Elliott M McMillan

    Full Text Available Hypertension is a cardiovascular disease associated with deleterious effects in skeletal and cardiac muscle. Autophagy is a degradative process essential to muscle health. Acute exercise can alter autophagic signaling. Therefore, we aimed to characterize the effects of chronic endurance exercise on autophagy in skeletal and cardiac muscle of normotensive and hypertensive rats. Male Wistar Kyoto (WKY and spontaneously hypertensive rats (SHR were assigned to a sedentary condition or 6 weeks of treadmill running. White gastrocnemius (WG of hypertensive rats had higher (p<0.05 caspase-3 and proteasome activity, as well as elevated calpain activity. In addition, skeletal muscle of hypertensive animals had elevated (p<0.05 ATG7 and LC3I protein, LAMP2 mRNA, and cathepsin activity, indicative of enhanced autophagic signaling. Interestingly, chronic exercise training increased (p<0.05 Beclin-1, LC3, and p62 mRNA as well as proteasome activity, but reduced (p<0.05 Beclin-1 and ATG7 protein, as well as decreased (p<0.05 caspase-3, calpain, and cathepsin activity. Left ventricle (LV of hypertensive rats had reduced (p<0.05 AMPKα and LC3II protein, as well as elevated (p<0.05 p-AKT, p-p70S6K, LC3I and p62 protein, which collectively suggest reduced autophagic signaling. Exercise training had little effect on autophagy-related signaling factors in LV; however, exercise training increased (p<0.05 proteasome activity but reduced (p<0.05 caspase-3 and calpain activity. Our results suggest that autophagic signaling is altered in skeletal and cardiac muscle of hypertensive animals. Regular aerobic exercise can effectively alter the proteolytic environment in both cardiac and skeletal muscle, as well as influence several autophagy-related factors in skeletal muscle of normotensive and hypertensive rats.

  13. Preservation of skeletal muscle mitochondrial content in older adults: relationship between mitochondria, fibre type and high-intensity exercise training.

    Science.gov (United States)

    Wyckelsma, Victoria L; Levinger, Itamar; McKenna, Michael J; Formosa, Luke E; Ryan, Michael T; Petersen, Aaron C; Anderson, Mitchell J; Murphy, Robyn M

    2017-06-01

    Ageing is associated with an upregulation of mitochondrial dynamics proteins mitofusin 2 (Mfn2) and mitochondrial dynamics protein 49 (MiD49) in human skeletal muscle with the increased abundance of Mfn2 being exclusive to type II muscle fibres. These changes occur despite a similar content of mitochondria, as measured by COXIV, NDUFA9 and complexes in their native states (Blue Native PAGE). Following 12 weeks of high-intensity training (HIT), older adults exhibit a robust increase in mitochondria content, while there is a decline in Mfn2 in type II fibres. We propose that the upregulation of Mfn2 and MiD49 with age may be a protective mechanism to protect against mitochondrial dysfunction, in particularly in type II skeletal muscle fibres, and that exercise may have a unique protective effect negating the need for an increased turnover of mitochondria. Mitochondrial dynamics proteins are critical for mitochondrial turnover and maintenance of mitochondrial health. High-intensity interval training (HIT) is a potent training modality shown to upregulate mitochondrial content in young adults but little is known about the effects of HIT on mitochondrial dynamics proteins in older adults. This study investigated the abundance of protein markers for mitochondrial dynamics and mitochondrial content in older adults compared to young adults. It also investigated the adaptability of mitochondria to 12 weeks of HIT in older adults. Both older and younger adults showed a higher abundance of mitochondrial respiratory chain subunits COXIV and NDUFA9 in type I compared with type II fibres, with no difference between the older adults and young groups. In whole muscle homogenates, older adults had higher mitofusin-2 (Mfn2) and mitochondrial dynamics protein 49 (MiD49) contents compared to the young group. Also, older adults had higher levels of Mfn2 in type II fibres compared with young adults. Following HIT in older adults, MiD49 and Mfn2 levels were not different in whole

  14. Exercise training and return to a well-balanced diet activate the neuregulin 1/ErbB pathway in skeletal muscle of obese rats.

    Science.gov (United States)

    Ennequin, Gaël; Boisseau, Nathalie; Caillaud, Kevin; Chavanelle, Vivien; Gerbaix, Maude; Metz, Lore; Etienne, Monique; Walrand, Stéphane; Masgrau, Aurélie; Guillet, Christelle; Courteix, Daniel; Niu, Airu; Li, Yi-Ping; Capel, Fréderic; Sirvent, Pascal

    2015-06-15

    Some studies suggest that neuregulin 1 (NRG1) could be involved in the regulation of skeletal muscle energy metabolism in rodents. Here we assessed whether unbalanced diet is associated with alterations of the NRG1 signalling pathway and whether exercise and diet might restore NRG1 signalling in skeletal muscle of obese rats. We show that diet-induced obesity does not impair NRG1 signalling in rat skeletal muscle. We also report that endurance training and a well-balanced diet activate the NRG1 signalling in skeletal muscle of obese rats, possibly via a new mechanism mediated by the protease ADAM17. These results suggest that some beneficial effects of physical activity and diet in obese rats could be partly explained by stimulation of the NRG1 signalling pathway. Some studies suggest that the signalling pathway of neuregulin 1 (NRG1), a protein involved in the regulation of skeletal muscle metabolism, could be altered by nutritional and exercise interventions. We hypothesized that diet-induced obesity could lead to alterations of the NRG1 signalling pathway and that chronic exercise could improve NRG1 signalling in rat skeletal muscle. To test this hypothesis, male Wistar rats received a high fat/high sucrose (HF/HS) diet for 16 weeks. At the end of this period, NRG1 and ErbB expression/activity in skeletal muscle was assessed. The obese rats then continued the HF/HS diet or were switched to a well-balanced diet. Moreover, in both groups, half of the animals also performed low intensity treadmill exercise training. After another 8 weeks, NRG1 and ErbB expression/activity in skeletal muscle were tested again. The 16 week HF/HS diet induced obesity, but did not significantly affect the NRG1/ErbB signalling pathway in rat skeletal muscle. Conversely, after the switch to a well-balanced diet, NRG1 cleavage ratio and ErbB4 amount were increased. Chronic exercise training also promoted NRG1 cleavage, resulting in increased ErbB4 phosphorylation. This result was

  15. Nitric oxide agents impair insulin-mediated signal transduction in rat skeletal muscle

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    Ragoobirsingh Dalip

    2006-05-01

    Full Text Available Abstract Background Evidence demonstrates that exogenously administered nitric oxide (NO can induce insulin resistance in skeletal muscle. We have investigated the modulatory effects of two NO donors, S-nitroso-N-acetyl-D, L-penicillamine (SNAP and S-nitrosoglutathione (GSNO on the early events in insulin signaling in rat skeletal myocytes. Results Skeletal muscle cells from 6–8 week old Sprague-Dawley rats were treated with SNAP or GSNO (25 ng/ml in the presence or absence of glucose (25 mM and insulin (100 nM. Cellular insulin receptor-β levels and tyrosine phosphorylation in IRS-1 were significantly reduced, while serine phosphorylation in IRS-1 was significantly increased in these cells, when compared to the insulin-stimulated control. Reversal to near normal levels was achieved using the NO scavenger, 2-(4-carboxyphenyl-4, 4, 5, 5-tetramethylimidazoline-1-oxyl 3-oxide (carboxy-PTIO. Conclusion These data suggest that NO is a potent modulator of insulin-mediated signal transduction and may play a significant role in the pathogenesis of type 2 diabetes mellitus.

  16. Changes in calmodulin concentration and cyclic 3',5'-nucleotide phosphodiesterase activity in skeletal muscle of hyper- and hypothyroid rats.

    Science.gov (United States)

    Mano, T; Iwase, K; Yoshimochi, I; Sawai, Y; Oda, N; Nishida, Y; Mokuno, T; Kotake, M; Nakai, A; Hayakawa, N

    1995-08-01

    Hyper- and hypothyroid states occasionally induce skeletal muscle dysfunction i.e. periodic paralysis and thyroid myopathy. The etiology of these diseases remains unclear, but several findings suggest that the catecholamine-beta-receptor-cAMP system or other messenger systems are disturbed in these diseases. In this context, we evaluated changes in the cyclic 3',5'-nucleotide metabolic enzyme, cyclic 3',5'-nucleotide phosphodiesterase (PDE) and calmodulin concentrations in skeletal muscles of hyper- and hypothyroid rats. Activities of cyclic AMP-PDE were low in skeletal muscle both from hyper- and hypothyroid rats, and calmodulin concentration was high in hyperthyroid and low in hypothyroid rats, as compared with normal rats. DE-52 column chromatographic analysis showed that the cGMP hydrolytic activity in peak I and the cAMP hydrolytic activity in peak II were decreased in hypothyroid rats, whereas cAMP hydrolytic activity in peak III was unchanged. The cAMP hydrolytic activity in peak III was decreased in hyperthyroid rats, but the activities in peaks I and II were unchanged. These findings indicate that cAMP and calmodulin may have some role in skeletal muscle function in the hyperthyroid state, and that cAMP and calmodulin-dependent metabolism may be suppressed in the hypothyroid state.

  17. Faster and stronger manifestation of mitochondrial diseases in skeletal muscle than in heart related to cytosolic inorganic phosphate (Pi) accumulation.

    Science.gov (United States)

    Korzeniewski, Bernard

    2016-08-01

    A model of the cell bioenergetic system was used to compare the effect of oxidative phosphorylation (OXPHOS) deficiencies in a broad range of moderate ATP demand in skeletal muscle and heart. Computer simulations revealed that kinetic properties of the system are similar in both cases despite the much higher mitochondria content and "basic" OXPHOS activity in heart than in skeletal muscle, because of a much higher each-step activation (ESA) of OXPHOS in skeletal muscle than in heart. Large OXPHOS deficiencies lead in both tissues to a significant decrease in oxygen consumption (V̇o2) and phosphocreatine (PCr) and increase in cytosolic ADP, Pi, and H(+) The main difference between skeletal muscle and heart is a much higher cytosolic Pi concentration in healthy tissue and much higher cytosolic Pi accumulation (level) at low OXPHOS activities in the former, caused by a higher PCr level in healthy tissue (and higher total phosphate pool) and smaller Pi redistribution between cytosol and mitochondria at OXPHOS deficiency. This difference does not depend on ATP demand in a broad range. A much greater Pi increase and PCr decrease during rest-to-moderate work transition in skeletal muscle at OXPHOS deficiencies than at normal OXPHOS activity significantly slows down the V̇o2 on-kinetics. Because high cytosolic Pi concentrations cause fatigue in skeletal muscle and can compromise force generation in skeletal muscle and heart, this system property can contribute to the faster and stronger manifestation of mitochondrial diseases in skeletal muscle than in heart. Shortly, skeletal muscle with large OXPHOS deficiencies becomes fatigued already during low/moderate exercise. Copyright © 2016 the American Physiological Society.

  18. PLASTICITY OF SKELETAL MUSCLE STUDIED BY STEREOLOGY

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    Ida Eržen

    2011-05-01

    Full Text Available The present contribution provides an overview of stereological methods applied in the skeletal muscle research at the Institute of Anatomy of the Medical Faculty in Ljubljana. Interested in skeletal muscle plasticity we studied three different topics: (i expression of myosin heavy chain isoforms in slow and fast muscles under experimental conditions, (ii frequency of satellite cells in young and old human and rat muscles and (iii capillary supply of rat fast and slow muscles. We analysed the expression of myosin heavy chain isoforms within slow rat soleus and fast extensor digitorum longus muscles after (i homotopic and heterotopic transplantation of both muscles, (ii low frequency electrical stimulation of the fast muscle and (iii transposition of the fast nerve to the slow muscle. The models applied were able to turn the fast muscle into a completely slow muscle, but not vice versa. One of the indicators for the regenerative potential of skeletal muscles is its satellite cell pool. The estimated parameters, number of satellite cells per unit fibre length, corrected to the reference sarcomere length (Nsc/Lfib and number of satellite cells per number of nuclei (myonuclei and satellite cell nuclei (Nsc/Nnucl indicated that the frequency of M-cadherin stained satellite cells declines in healthy old human and rat muscles compared to young muscles. To access differences in capillary densities among slow and fast muscles and slow and fast muscle fibres, we have introduced Slicer and Fakir methods, and tested them on predominantly slow and fast rat muscles. Discussing three different topics that require different approach, the present paper reflects the three decades of the development of stereological methods: 2D analysis by simple point counting in the 70's, the disector in the 80's and virtual spatial probes in the 90's. In all methods the interactive computer assisted approach was utilised.

  19. Aerobic characteristics of red kangaroo skeletal muscles: is a high aerobic capacity matched by muscle mitochondrial and capillary morphology as in placental mammals?

    Science.gov (United States)

    Dawson, Terence J; Mifsud, Brock; Raad, Matthew C; Webster, Koa N

    2004-07-01

    Marsupials and placentals together comprise the Theria, the advanced mammals, but they have had long independent evolutionary histories, with the last common ancestor occurring more than 125 million years ago. Although in the past the marsupials were considered to be metabolically 'primitive', the red kangaroo Macropus rufus has been reported to have an aerobic capacity (VO2max) comparable to that of the most 'athletic' of placentals such as dogs. However, kangaroos travel at moderate speeds with lower relative cost than quadrupedal placentals. Given the long independent evolution of the two therian groups, and their unusual locomotor energetics, do kangaroos achieve their high aerobic capacity using the same structural and functional mechanisms used by (athletic) placentals? Red kangaroo skeletal muscle morphometry matched closely the general aerobic characteristics of placental mammals. The relationship between total mitochondrial volume in skeletal muscle and VO2max during exercise was identical to that in quadrupedal placentals, and differed from that in bipedal humans. As for placentals generally, red kangaroo mitochondrial oxygen consumption at VO2max was 4.7 ml O2 min(-1) ml(-1) of mitochondria. Also, the inner mitochondrial membrane densities were 35.8 +/- 0.7 m2 ml(-1) of mitochondria, which is the same as for placental mammals, and the same pattern of similarity was seen for capillary densities and volumes. The overall data for kangaroos was equivalent to that seen in athletic placentals such as dogs and pronghorns. Total skeletal muscle mass was high, being around 50% of body mass, and was concentrated around the pelvis and lower back. The majority of the muscles sampled had relatively high mitochondrial volume densities, in the range 8.8-10.6% in the major locomotor muscles. Again, capillary densities and capillary blood volumes followed the pattern seen for mitochondria. Our results indicate that the red kangaroo, despite its locomotion and extreme

  20. Celastrol Protects against Antimycin A-Induced Insulin Resistance in Human Skeletal Muscle Cells

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    Mohamad Hafizi Abu Bakar

    2015-05-01

    Full Text Available Mitochondrial dysfunction and inflammation are widely accepted as key hallmarks of obesity-induced skeletal muscle insulin resistance. The aim of the present study was to evaluate the functional roles of an anti-inflammatory compound, celastrol, in mitochondrial dysfunction and insulin resistance induced by antimycin A (AMA in human skeletal muscle cells. We found that celastrol treatment improved insulin-stimulated glucose uptake activity of AMA-treated cells, apparently via PI3K/Akt pathways, with significant enhancement of mitochondrial activities. Furthermore, celastrol prevented increased levels of cellular oxidative damage where the production of several pro-inflammatory cytokines in cultures cells was greatly reduced. Celastrol significantly increased protein phosphorylation of insulin signaling cascades with amplified expression of AMPK protein and attenuated NF-κB and PKC θ activation in human skeletal muscle treated with AMA. The improvement of insulin signaling pathways by celastrol was also accompanied by augmented GLUT4 protein expression. Taken together, these results suggest that celastrol may be advocated for use as a potential therapeutic molecule to protect against mitochondrial dysfunction-induced insulin resistance in human skeletal muscle cells.

  1. Nitric oxide and Na,K-ATPase activity in rat skeletal muscle.

    Science.gov (United States)

    Juel, C

    2016-04-01

    It has been suggested that nitric oxide (NO) stimulates the Na,K-ATPase in cardiac myocytes. Therefore, the aims of this study were to investigate whether NO increases Na,K-ATPase activity in skeletal muscle and, if that is the case, to identify the underlying mechanism. The study used isolated rat muscle, muscle homogenates and purified membranes as model systems. Na,K-ATPase activity was quantified from phosphate release due to ATP hydrolysis. Exposure to the NO donor spermine NONOate (10 μm) increased the maximal Na,K-ATPase activity by 27% in isolated glycolytic muscles, but had no effect in oxidative muscles. Spermine NONOate increased the maximal Na,K-ATPase activity by 58% (P Na,K-ATPase α-isoform. Incubation with cGMP (1 mm) increased the maximal Na,K-ATPase activity in homogenates from glycolytic muscle by 16% (P Na,K-ATPase in glycolytic skeletal muscle. Direct S-nitrosylation and interference with S-glutathionylation seem to be excluded. In addition, phosphorylation of phospholemman at serine 68 is not involved. Most likely, the NO/cGMP/protein kinase G signalling pathway is involved. © 2015 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

  2. A short period of high-intensity interval training improves skeletal muscle mitochondrial function and pulmonary oxygen uptake kinetics

    DEFF Research Database (Denmark)

    Christensen, Peter Møller; Jacobs, Robert A; Bonne, Thomas Christian

    2016-01-01

    The aim of the present study was to examine whether improvements in pulmonary V̇O2 kinetics following a short period of high-intensity training (HIT) would be associated with improved skeletal muscle mitochondrial function. Ten untrained male volunteers (age: 26 ± 2; mean ± SD) performed six HIT...

  3. Chinese medicine Jinlida (JLD) ameliorates high-fat-diet induced insulin resistance in rats by reducing lipid accumulation in skeletal muscle.

    Science.gov (United States)

    Zang, Sha-Sha; Song, An; Liu, Yi-Xuan; Wang, Chao; Song, Guang-Yao; Li, Xiao-Ling; Zhu, Ya-Jun; Yu, Xian; Li, Ling; Liu, Chen-Xi; Kang, Jun-Cong; Ren, Lu-Ping

    2015-01-01

    The present paper reports the effects of Jinlida (JLD), a traditional Chinese medicine which has been given as a treatment for high-fat-diet (HFD)-induced insulin resistance. A randomized controlled experiment was conducted to provide evidence in support of the affects of JLD on insulin resistance induced by HFD. The affect of JLD on blood glucose, lipid, insulin, adiponectin, alanine aminotransferase (ALT), aspartate aminotransferase (AST) and total bilirubin (TBIL) in serum and lipid content in skeletal muscle was measured. Genes and proteins of the AMPK signaling pathway were analyzed by real time RT-PCR and Western blot. Adiponectin receptor 1 and 2 (ADIPOR1, ADIPOR2) and other genes involved in mitochondrial function and fat oxidation were analyzed by real time RT-PCR. Histological staining was also performed. JLD or pioglitazone administration ameliorated fasting plasma levels of glucose, insulin, triglyceride (TG), total cholesterol (TC), ALT, AST and non-esterified fatty acid (NEFA) (P < 0.05). Treatment with JLD or pioglitazone significantly reverted muscle lipid content (P < 0.05). JLD (1.5 g/kg) significantly increased plasma adiponectin concentration by 60.17% and increased AMPK and acetyl-CoA carboxylase (ACC) phosphorylation in skeletal muscle (P < 0.05). JLD administration increased levels of ADIPOR1 and ADIPOR2 by 1.48 and 1.29 respectively. Levels of genes involved in mitochondrial function and fat oxidation were increased. This study provides the molecular mechanism by which JLD ameliorates HFD-induced insulin resistance in rats.

  4. Transient gestational and neonatal hypothyroidism-induced specific changes in androgen receptor expression in skeletal and cardiac muscles of adult rat.

    Science.gov (United States)

    Annapoorna, K; Anbalagan, J; Neelamohan, R; Vengatesh, G; Stanley, J; Amudha, G; Aruldhas, M M

    2013-03-01

    The present study aims to identify the association between androgen status and metabolic activity in skeletal and cardiac muscles of adult rats with transient gestational/neonatal-onset hypothyroidism. Pregnant and lactating rats were made hypothyroid by exposing to 0.05% methimazole in drinking water; gestational exposure was from embryonic day 9-14 (group II) or 21 (group III), lactational exposure was from postnatal day 1-14 (group IV) or 29 (group V). Serum was collected for hormone assay. Androgen receptor status, Glu-4 expression, and enzyme activities were assessed in the skeletal and cardiac muscles. Serum testosterone and estradiol levels decreased in adult rats of groups II and III, whereas testosterone remained normal but estradiol increased in group IV and V, when compared to coeval control. Androgen receptor ligand binding activity increased in both muscle phenotypes with a consistent increase in the expression level of its mRNA and protein expressions except in the forelimb of adult rats with transient hypothyroidism (group II-V). Glut-4 expression remained normal in skeletal and cardiac muscle of experimental rats. Specific activity of hexokinase and lactate dehydrogenase increased in both muscle phenotypes whereas, creatine kinase activity increased in skeletal muscles alone. It is concluded that transient gestational/lactational exposure to methimazole results in hypothyroidism during prepuberal life whereas it increases AR status and glycolytic activity in skeletal and cardiac muscles even at adulthood. Thus, the present study suggests that euthyroid status during prenatal and early postnatal life is essential to have optimal AR status and metabolic activity at adulthood. © Georg Thieme Verlag KG Stuttgart · New York.

  5. THE INFLUENCE OF DIFFERENT THYROID STATUS ON ELECTROPHYSIOLOGICAL AND MYOGRAPHICAL PARAMETERS OF SKELETAL MUSCLES CONTRACTION IN WHITE RATS.

    Science.gov (United States)

    Stanishevskaya, T I; Anosov, I P

    In experiments on white rats the character of effect of experimental hyperthyroidism was studied on the skeletal muscle (m. tibialis anterior) of white rats. It is shown that at experimental hyperthyroidism (rectal temperature of 38,5±0,10С) a muscle acquires high functional capabilities. It is shown that the latent period of generation and the time of development of positive wave “М-respones” are (-32%) and (- 22%). The latent period of shortening of muscle diminishes (- 23%) at single contraction. During experimental thyrotoxicosis (rectal temperature of 39,4±0,2 0 С) we observed physiopathological changes in the functional state of skeletal muscle: the lengthening of the latent period of generation of “М-respones” (+21%), an increase in the time of development of positive wave (+54%) and of latent period of shortening of muscle (+14%). It is concluded that in experimental hyperthyroidism and thyrotoxicosis the functional state of skeletal muscle changed in different directions.

  6. Comprehensive analysis of tropomyosin isoforms in skeletal muscles by top-down proteomics.

    Science.gov (United States)

    Jin, Yutong; Peng, Ying; Lin, Ziqing; Chen, Yi-Chen; Wei, Liming; Hacker, Timothy A; Larsson, Lars; Ge, Ying

    2016-04-01

    Mammalian skeletal muscles are heterogeneous in nature and are capable of performing various functions. Tropomyosin (Tpm) is a major component of the thin filament in skeletal muscles and plays an important role in controlling muscle contraction and relaxation. Tpm is known to consist of multiple isoforms resulting from different encoding genes and alternative splicing, along with post-translational modifications. However, a systematic characterization of Tpm isoforms in skeletal muscles is still lacking. Therefore, we employed top-down mass spectrometry (MS) to identify and characterize Tpm isoforms present in different skeletal muscles from multiple species, including swine, rat, and human. Our study revealed that Tpm1.1 and Tpm2.2 are the two major Tpm isoforms in swine and rat skeletal muscles, whereas Tpm1.1, Tpm2.2, and Tpm3.12 are present in human skeletal muscles. Tandem MS was utilized to identify the sequences of the major Tpm isoforms. Furthermore, quantitative analysis revealed muscle-type specific differences in the abundance of un-modified and modified Tpm isoforms in rat and human skeletal muscles. This study represents the first systematic investigation of Tpm isoforms in skeletal muscles, which not only demonstrates the capabilities of top-down MS for the comprehensive characterization of skeletal myofilament proteins but also provides the basis for further studies on these Tpm isoforms in muscle-related diseases.

  7. Mitochondrial biogenesis and angiogenesis in skeletal muscle of the elderly

    DEFF Research Database (Denmark)

    Iversen, Ninna; Krustrup, Peter; Rasmussen, Hans N

    2011-01-01

    The aim of this study was to test the hypotheses that 1) skeletal muscles of elderly subjects can adapt to a single endurance exercise bout and 2) endurance trained elderly subjects have higher expression/activity of oxidative and angiogenic proteins in skeletal muscle than untrained elderly peop...

  8. Expression of interleukin-15 and inflammatory cytokines in skeletal muscles of STZ-induced diabetic rats: effect of resistance exercise training.

    Science.gov (United States)

    Molanouri Shamsi, M; Hassan, Z H; Gharakhanlou, R; Quinn, L S; Azadmanesh, K; Baghersad, L; Isanejad, A; Mahdavi, M

    2014-05-01

    Skeletal muscle atrophy is associated with type-1 diabetes. Skeletal muscle is the source of pro- and anti-inflammatory cytokines that can mediate muscle hypertrophy and atrophy, while resistance exercise can modulate both muscle mass and muscle cytokine expression. This study determined the effects of a 5-week resistance exercise training regimen on the expression of muscle cytokines in healthy and streptozotocin-induced diabetic rats, with special emphasis on interleukin-15 (IL-15), a muscle-derived cytokine proposed to be involved in muscle hypertrophy or responses to stress. Induction of diabetes reduced muscle weight in both the fast flexor hallucis longus (FHL) and slow soleus muscles, while resistance training preserved FHL muscle weight in diabetic rats. IL-15 protein content was increased by training in both FHL and soleus muscles, as well as serum, in normal and diabetic rats. With regard to proinflammatory cytokines, muscle IL-6 levels were increased in diabetic rats, while training decreased muscle IL-6 levels in diabetic rats; training had no effect on FHL muscle IL-6 levels in healthy rats. Also, tumor necrosis factor-alpha (TNF-α) and IL-1β levels were increased by diabetes, but not changed by training. In conclusion, we found that in diabetic rats, resistance training increased muscle and serum IL-15 levels, decreased muscle IL-6 levels, and preserved FHL muscle mass.

  9. Mitochondrial-related proteomic changes during obesity and fasting in mice are greater in the liver than skeletal muscles.

    Science.gov (United States)

    Nesteruk, Monika; Hennig, Ewa E; Mikula, Michal; Karczmarski, Jakub; Dzwonek, Artur; Goryca, Krzysztof; Rubel, Tymon; Paziewska, Agnieszka; Woszczynski, Marek; Ledwon, Joanna; Dabrowska, Michalina; Dadlez, Michal; Ostrowski, Jerzy

    2014-03-01

    Although mitochondrial dysfunction is implicated in the pathogenesis of obesity, the molecular mechanisms underlying obesity-related metabolic abnormalities are not well established. We performed mitochondrial quantitative proteomic and whole transcriptome analysis followed by functional annotations within liver and skeletal muscles, using fasted and non-fasted 16- and 48-week-old high-fat diet (HFD)-fed and normal diet-fed (control group) wild-type C56BL/6J mice, and hyperphagic ob/ob and db/db obese mice. Our study identified 1,675 and 704 mitochondria-associated proteins with at least two peptides in liver and muscle, respectively. Of these, 221 liver and 44 muscle proteins were differentially expressed (adjusted p values ≤ 0.05) between control and all obese mice, while overnight fasting altered expression of 107 liver and 35 muscle proteins. In the liver, we distinguished a network of 27 proteins exhibiting opposite direction of expression changes in HFD-fed and hyperphagic mice when compared to control. The network centered on cytochromes P450 3a11 (Cyp3a11) and 4a14 (Cyp4a14), and fructose-bisphosphate aldolase B (Aldob) proteins which bridged proteins cluster involved in Metabolism of xenobiotics with proteins engaged in Fatty acid metabolism and PPAR signaling pathways. Functional annotations revealed that most of the hepatic molecular alterations, which characterized both obesity and fasting, related to different aspects of energy metabolism (such as Fatty acid metabolism, Peroxisome, and PPAR signaling); however, only a limited number of functional annotations could be selected from skeletal muscle data sets. Thus, our comprehensive molecular overview revealed that both obesity and fasting states induce more pronounced mitochondrial proteome changes in the liver than in the muscles.

  10. Anesthesia with propofol induces insulin resistance systemically in skeletal and cardiac muscles and liver of rats

    Energy Technology Data Exchange (ETDEWEB)

    Yasuda, Yoshikazu; Fukushima, Yuji; Kaneki, Masao [Department of Anaesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Shriners Hospitals for Children, Harvard Medical School, Boston, MA 02114 (United States); Martyn, J.A. Jeevendra, E-mail: jmartyn@partners.org [Department of Anaesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Shriners Hospitals for Children, Harvard Medical School, Boston, MA 02114 (United States)

    2013-02-01

    Highlights: ► Propofol, as a model anesthetic drug, induced whole body insulin resistance. ► Propofol anesthesia decreased glucose infusion rate to maintain euglycemia. ► Propofol decreased insulin-mediated glucose uptake in skeletal and cardiac muscles. ► Propofol increased hepatic glucose output confirming hepatic insulin resistance. -- Abstract: Hyperglycemia together with hepatic and muscle insulin resistance are common features in critically ill patients, and these changes are associated with enhanced inflammatory response, increased susceptibility to infection, muscle wasting, and worsened prognosis. Tight blood glucose control by intensive insulin treatment may reduce the morbidity and mortality in intensive care units. Although some anesthetics have been shown to cause insulin resistance, it remains unknown how and in which tissues insulin resistance is induced by anesthetics. Moreover, the effects of propofol, a clinically relevant intravenous anesthetic, also used in the intensive care unit for sedation, on insulin sensitivity have not yet been investigated. Euglycemic hyperinsulinemic clamp study was performed in rats anesthetized with propofol and conscious unrestrained rats. To evaluate glucose uptake in tissues and hepatic glucose output [{sup 3}H]glucose and 2-deoxy[{sup 14}C]glucose were infused during the clamp study. Anesthesia with propofol induced a marked whole-body insulin resistance compared with conscious rats, as reflected by significantly decreased glucose infusion rate to maintain euglycemia. Insulin-stimulated tissue glucose uptake was decreased in skeletal muscle and heart, and hepatic glucose output was increased in propofol anesthetized rats. Anesthesia with propofol induces systemic insulin resistance along with decreases in insulin-stimulated glucose uptake in skeletal and heart muscle and attenuation of the insulin-mediated suppression of hepatic glucose output in rats.

  11. Anesthesia with propofol induces insulin resistance systemically in skeletal and cardiac muscles and liver of rats

    International Nuclear Information System (INIS)

    Yasuda, Yoshikazu; Fukushima, Yuji; Kaneki, Masao; Martyn, J.A. Jeevendra

    2013-01-01

    Highlights: ► Propofol, as a model anesthetic drug, induced whole body insulin resistance. ► Propofol anesthesia decreased glucose infusion rate to maintain euglycemia. ► Propofol decreased insulin-mediated glucose uptake in skeletal and cardiac muscles. ► Propofol increased hepatic glucose output confirming hepatic insulin resistance. -- Abstract: Hyperglycemia together with hepatic and muscle insulin resistance are common features in critically ill patients, and these changes are associated with enhanced inflammatory response, increased susceptibility to infection, muscle wasting, and worsened prognosis. Tight blood glucose control by intensive insulin treatment may reduce the morbidity and mortality in intensive care units. Although some anesthetics have been shown to cause insulin resistance, it remains unknown how and in which tissues insulin resistance is induced by anesthetics. Moreover, the effects of propofol, a clinically relevant intravenous anesthetic, also used in the intensive care unit for sedation, on insulin sensitivity have not yet been investigated. Euglycemic hyperinsulinemic clamp study was performed in rats anesthetized with propofol and conscious unrestrained rats. To evaluate glucose uptake in tissues and hepatic glucose output [ 3 H]glucose and 2-deoxy[ 14 C]glucose were infused during the clamp study. Anesthesia with propofol induced a marked whole-body insulin resistance compared with conscious rats, as reflected by significantly decreased glucose infusion rate to maintain euglycemia. Insulin-stimulated tissue glucose uptake was decreased in skeletal muscle and heart, and hepatic glucose output was increased in propofol anesthetized rats. Anesthesia with propofol induces systemic insulin resistance along with decreases in insulin-stimulated glucose uptake in skeletal and heart muscle and attenuation of the insulin-mediated suppression of hepatic glucose output in rats

  12. Response of macrophages in rat skeletal muscle after eccentric exercise.

    Science.gov (United States)

    Zuo, Qun; Wang, Shu-Chen; Yu, Xin-Kai; Chao, Wei-Wei

    2018-04-01

    Macrophages are known to be important for healing numerous injured tissues depending on their functional phenotypes in response to different stimuli. The objective of this study was to reveal macrophage phenotypic changes involved in exercise-induced skeletal muscle injury and regeneration. Adult male Sprague-Dawley rats experienced one session of downhill running (16° decline, 16 m/min) for 90 min. After exercise the blood and soleus muscles were collected at 0 h, 6 h, 12 h, 1 d, 2 d, 3 d, 1 w and 2 w after exercise, separately. It was showed that CD68 + M1 macrophages mainly infiltrated into muscle necrotic sites at 1-3 d, while CD163 + M2 macrophages were present in muscles from 0 h to 2 weeks after exercise. Using transmission electron microscopy, we observed activated satellite cells 1 d after exercise. Th1-associated transcripts of iNOS and Ccl2 were inhibited post exercise, while COX-2 mRNA was dramatically increased 12 h after running (p < 0.01). M2 phenotype marker Arg-1 increased 12 h and 3 d (p < 0.05, p < 0.01) after exercise, and Clec10a and Mrc2 were up-regulated in muscles 12 h following exercise (p < 0.05, p < 0.05). The data demonstrate the dynamic patterns of macrophage phenotype in skeletal muscle upon eccentric exercise stimuli, and M1 and M2 phenotypes perform different functions during exercise-induced skeletal muscle injury and recovery. Copyright © 2018 Daping Hospital and the Research Institute of Surgery of the Third Military Medical University. Production and hosting by Elsevier B.V. All rights reserved.

  13. Inhibitors of the proteasome reduce the accelerated proteolysis in atrophying rat skeletal muscles.

    Science.gov (United States)

    Tawa, N E; Odessey, R; Goldberg, A L

    1997-07-01

    Several observations have suggested that the enhanced proteolysis and atrophy of skeletal muscle in various pathological states is due primarily to activation of the ubiquitin-proteasome pathway. To test this idea, we investigated whether peptide aldehyde inhibitors of the proteasome, N-acetyl-leucyl-leucyl-norleucinal (LLN), or the more potent CBZ-leucyl-leucyl-leucinal (MG132) suppressed proteolysis in incubated rat skeletal muscles. These agents (e.g., MG132 at 10 microM) inhibited nonlysosomal protein breakdown by up to 50% (P protein synthesis or amino acid pools, but improved overall protein balance in the muscle. Upon treatment with MG132, ubiquitin-conjugated proteins accumulated in the muscle. The inhibition of muscle proteolysis correlated with efficacy against the proteasome, although these agents could also inhibit calpain-dependent proteolysis induced with Ca2+. These inhibitors had much larger effects on proteolysis in atrophying muscles than in controls. In the denervated soleus undergoing atrophy, the increase in ATP-dependent proteolysis was reduced 70% by MG132 (P muscle proteolysis induced by administering thyroid hormones was reduced 40-70% by the inhibitors. Finally, in rats made septic by cecal puncture, the increase in muscle proteolysis was completely blocked by MG132. Thus, the enhanced proteolysis in many catabolic states (including denervation, hyperthyroidism, and sepsis) is due to a proteasome-dependent pathway, and inhibition of proteasome function may be a useful approach to reduce muscle wasting.

  14. Early energy metabolism-related molecular events in skeletal muscle of diabetic rats: The effects of l-arginine and SOD mimic.

    Science.gov (United States)

    Stancic, Ana; Filipovic, Milos; Ivanovic-Burmazovic, Ivana; Masovic, Sava; Jankovic, Aleksandra; Otasevic, Vesna; Korac, Aleksandra; Buzadzic, Biljana; Korac, Bato

    2017-06-25

    Considering the vital role of skeletal muscle in control of whole-body metabolism and the severity of long-term diabetic complications, we aimed to reveal the molecular pattern of early diabetes-related skeletal muscle phenotype in terms of energy metabolism, focusing on regulatory mechanisms, and the possibility to improve it using two redox modulators, l-arginine and superoxide dismutase (SOD) mimic. Alloxan-induced diabetic rats (120 mg/kg) were treated with l-arginine or the highly specific SOD mimic, M40403, for 7 days. As appropriate controls, non-diabetic rats received the same treatments. We found that l-arginine and M40403 restored diabetes-induced impairment of phospho-5'-AMP-activated protein kinase α (AMPKα) signaling by upregulating AMPKα protein itself and its downstream effectors, peroxisome proliferator-activated receptor-γ coactivator-1α and nuclear respiratory factor 1. Also, there was a restitution of the protein levels of oxidative phosphorylation components (complex I, complex II and complex IV) and mitofusin 2. Furthermore, l-arginine and M40403 induced translocation of glucose transporter 4 to the membrane and upregulation of protein of phosphofructokinase and acyl coenzyme A dehydrogenase, diminishing negative diabetic effects on limiting factors of glucose and lipid metabolism. Both treatments abolished diabetes-induced downregulation of sarcoplasmic reticulum calcium-ATPase proteins (SERCA 1 and 2). Similar effects of l-arginine and SOD mimic treatments suggest that disturbances in the superoxide/nitric oxide ratio may be responsible for skeletal muscle mitochondrial and metabolic impairment in early diabetes. Our results provide evidence that l-arginine and SOD mimics have potential in preventing and treating metabolic disturbances accompanying this widespread metabolic disease. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. The muscle contraction mode determines lymphangiogenesis differentially in rat skeletal and cardiac muscles by modifying local lymphatic extracellular matrix microenvironments.

    Science.gov (United States)

    Greiwe, L; Vinck, M; Suhr, F

    2016-05-01

    Lymphatic vessels are of special importance for tissue homeostasis, and increases of their density may foster tissue regeneration. Exercise could be a relevant tool to increase lymphatic vessel density (LVD); however, a significant lack of knowledge remains to understand lymphangiogenesis in skeletal muscles upon training. Interestingly, training-induced lymphangiogenesis has never been studied in the heart. We studied lymphangiogenesis and LVD upon chronic concentric and chronic eccentric muscle contractions in both rat skeletal (Mm. Edl and Sol) and cardiac muscles. We found that LVD decreased in both skeletal muscles specifically upon eccentric training, while this contraction increased LVD in cardiac tissue. These observations were supported by opposing local remodelling of lymphatic vessel-specific extracellular matrix components in skeletal and cardiac muscles and protein levels of lymphatic markers (Lyve-1, Pdpn, Vegf-C/D). Confocal microscopy further revealed transformations of lymphatic vessels into vessels expressing both blood (Cav-1) and lymphatic (Vegfr-3) markers upon eccentric training specifically in skeletal muscles. In addition and phenotype supportive, we found increased inflammation (NF-κB/p65, Il-1β, Ifn-γ, Tnf-α and MPO(+) cells) in eccentrically stressed skeletal, but decreased levels in cardiac muscles. Our data provide novel mechanistic insights into lymphangiogenic processes in skeletal and cardiac muscles upon chronic muscle contraction modes and demonstrate that both tissues adapt in opposing manners specifically to eccentric training. These data are highly relevant for clinical applications, because eccentric training serves as a sufficient strategy to increase LVD and to decrease inflammation in cardiac tissue, for example in order to reduce tissue abortion in transplantation settings. © 2015 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

  16. Effect of aqueous extract of saffron (crocus sativus L.) against gamma radiation-induced skeletal muscles damage in rats

    International Nuclear Information System (INIS)

    El-Tahawy, N.A; Said, U.Z

    2010-01-01

    Muscular strength is important in sport as well as in daily activities. Reactive oxygen species (ROS) and oxidative damage are the most important factors in radiation-induced acute damage to muscle tissue. Saffron, obtained from dried stigmas of Crocus sativus L. (Iridaceae), is a highly valued spice, commonly used in flavouring and food colouring in different parts of the world and is known to possess the richest source of carotenoids. The present study was designed to investigate the efficacy of an aqueous extract of saffron to protect against radiation-induced oxidative damage in rat's skeletal muscle. Saffron was supplemented orally, via gavages to rats at a dose of 80 mg/ kg body wt/ day for 2 week pre- and 1 week post-exposure to 5 Gy (one shot dose) of whole body gamma-irradiation. Animals were sacrificed 1, 2 and 3 weeks post radiation exposure. The results revealed that whole body gamma-irradiation of rats induce oxidative stress in skeletal muscles obvious by significant elevation in the level of thiobarbituric acid reactive substances associated with significant decreases in superoxide dismutase and catalase activities. Also, radiation-induces skeletal muscles damage evidenced by significant decreases in the level of pyruvic acid, creatine phosphokinase, glutamate dehydrogenase and glucose-6-phosphate dehydrogenase activities as well as significant increases in lactic acid, total iron, and copper and calcium levels. Saffron treated-irradiated rats showed significantly less severe damage and remarkable improvement in all the measured parameters, compared to irradiated rats. It could be concluded that saffron by attenuating radiation-induced oxidative stress might play a role in maintaining skeletal muscle integrity.

  17. Regenerative Potential of D-δ-Tocotrienol Rich Fraction on Crushed Skeletal Muscle of Diabetic Rats

    Directory of Open Access Journals (Sweden)

    Bijo Elsy

    2017-06-01

    Full Text Available Background: Delayed muscle growth and regeneration of skeletal muscle in diabetics is believed to be due to diabetic myopathy because of alteration in the skeletal muscle homeostatis. Since vitamin E is a natural antioxidant and is also important for the integrity of sarcolemma, the present study was designed to explore the muscle regenerative potency of d-δ-tocotrienol-rich fraction (d-δ-TRF on crushed skeletal muscle in healthy and diabetic rats. Materials and Methods: Diabetes was induced through single subcutaneous injection of alloxan (100 mg/kg. Twenty-four albino rats were divided into four groups; healthy control, diabetic control, healthy treated, and diabetic treated. Treated groups received injections orally, daily (200 mg/kg for 3 weeks. A horizontal skin incision was made on the shaved right mid-thigh region, by splitting the fascia between gluteus maximus and tensor fascia lata, and gluteus maximus was crushed with Kocher’s forceps. Skin wound was closed with an absorbable suture. The crushed muscle changes were studied by assessing the histopathological features, histomorphological measurements, and biochemical analyses on 3rd week following induction of injury. One-way “ANOVA” followed by Tukey’s test and Student t-test were used for statistical analysis of data. Results: Results obtained through various methods indicate that the d-δ-TRF treated groups have controlled glycemic status, improved antioxidant capacity, faster revascularization, re-innervation, regeneration of myofibers, and connective tissue remodeling. Conclusion: It is, therefore, concluded that the d-δ-TRF is a beneficial nutritional adjuvant for skeletal muscles’ structural and functional recovery after crushed injury in both healthy and diabetics. [J Interdiscip Histopathol 2017; 5(2.000: 36-42

  18. Age-associated disruption of molecular clock expression in skeletal muscle of the spontaneously hypertensive rat.

    Directory of Open Access Journals (Sweden)

    Mitsunori Miyazaki

    Full Text Available It is well known that spontaneously hypertensive rats (SHR develop muscle pathologies with hypertension and heart failure, though the mechanism remains poorly understood. Woon et al. (2007 linked the circadian clock gene Bmal1 to hypertension and metabolic dysfunction in the SHR. Building on these findings, we compared the expression pattern of several core-clock genes in the gastrocnemius muscle of aged SHR (80 weeks; overt heart failure compared to aged-matched control WKY strain. Heart failure was associated with marked effects on the expression of Bmal1, Clock and Rora in addition to several non-circadian genes important in regulating skeletal muscle phenotype including Mck, Ttn and Mef2c. We next performed circadian time-course collections at a young age (8 weeks; pre-hypertensive and adult age (22 weeks; hypertensive to determine if clock gene expression was disrupted in gastrocnemius, heart and liver tissues prior to or after the rats became hypertensive. We found that hypertensive/hypertrophic SHR showed a dampening of peak Bmal1 and Rev-erb expression in the liver, and the clock-controlled gene Pgc1α in the gastrocnemius. In addition, the core-clock gene Clock and the muscle-specific, clock-controlled gene Myod1, no longer maintained a circadian pattern of expression in gastrocnemius from the hypertensive SHR. These findings provide a framework to suggest a mechanism whereby chronic heart failure leads to skeletal muscle pathologies; prolonged dysregulation of the molecular clock in skeletal muscle results in altered Clock, Pgc1α and Myod1 expression which in turn leads to the mis-regulation of target genes important for mechanical and metabolic function of skeletal muscle.

  19. Effects of β-hydroxy-β-methylbutyrate on skeletal muscle mitochondrial content and dynamics, and lipids after 10 days of bed rest in older adults.

    Science.gov (United States)

    Standley, Robert A; Distefano, Giovanna; Pereira, Suzette L; Tian, Min; Kelly, Owen J; Coen, Paul M; Deutz, Nicolaas E P; Wolfe, Robert R; Goodpaster, Bret H

    2017-11-01

    Loss of muscle mass during periods of disuse likely has negative health consequences for older adults. We have previously shown that β-hydroxy-β-methylbutyrate (HMB) supplementation during 10 days of strict bed rest (BR) attenuates the loss of lean mass in older adults. To elucidate potential molecular mechanisms of HMB effects on muscle during BR and resistance training rehabilitation (RT), we examined mediators of skeletal muscle mitochondrial dynamics, autophagy and atrophy, and intramyocellular lipids. Nineteen older adults (60-76 yr) completed 10 days BR followed by 8-wk RT rehabilitation. Subjects were randomized to either HMB (3 g/day HMB; n = 11) or control (CON; n = 8) groups. Skeletal muscle cross-sectional area (CSA) was determined by histology from percutaneous vastus lateralis biopsies. We measured protein markers of mitochondrial content [oxidative phosphorylation (OXPHOS)], fusion and fission (MFN2, OPA1, FIS1, and DRP1), autophagy (Beclin1, LC3B, and BNIP3), and atrophy [poly-ubiquinated proteins (poly-ub)] by Western blot. Fatty acid composition of several lipid classes in skeletal muscle was measured by infusion-MS analysis. Poly-ub proteins and OXPHOS complex I increased in both groups following BR ( P HMB group ( P = 0.055). RT rehabilitation increased OXPHOS complex II protein ( P HMB group. In addition, higher levels of DRP1 and MFN2 were maintained in the HMB group after RT ( P HMB influences mitochondrial dynamics and lipid metabolism during disuse atrophy and rehabilitation. NEW & NOTEWORTHY Mitochondrial content and dynamics remained unchanged over 10 days of BR in older adults. HMB stimulated intramuscular lipid storage as triacylglycerol following 10 days of bed rest (BR) and maintained higher mitochondrial OXPHOS content and dynamics during the 8-wk resistance exercise rehabilitation program. Copyright © 2017 the American Physiological Society.

  20. Photothermal imaging of skeletal muscle mitochondria.

    Science.gov (United States)

    Tomimatsu, Toru; Miyazaki, Jun; Kano, Yutaka; Kobayashi, Takayoshi

    2017-06-01

    The morphology and topology of mitochondria provide useful information about the physiological function of skeletal muscle. Previous studies of skeletal muscle mitochondria are based on observation with transmission, scanning electron microscopy or fluorescence microscopy. In contrast, photothermal (PT) microscopy has advantages over the above commonly used microscopic techniques because of no requirement for complex sample preparation by fixation or fluorescent-dye staining. Here, we employed the PT technique using a simple diode laser to visualize skeletal muscle mitochondria in unstained and stained tissues. The fine mitochondrial network structures in muscle fibers could be imaged with the PT imaging system, even in unstained tissues. PT imaging of tissues stained with toluidine blue revealed the structures of subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondria and the swelling behavior of mitochondria in damaged muscle fibers with sufficient image quality. PT image analyses based on fast Fourier transform (FFT) and Grey-level co-occurrence matrix (GLCM) were performed to derive the characteristic size of mitochondria and to discriminate the image patterns of normal and damaged fibers.

  1. Induction of amino acid transporters expression by endurance exercise in rat skeletal muscle

    International Nuclear Information System (INIS)

    Murakami, Taro; Yoshinaga, Mariko

    2013-01-01

    Highlights: •Regulation of amino acid transporter expression in working muscle remains unclear. •Expression of amino acid transporters for leucine were induced by a bout of exercise. •Requirement of leucine in muscle cells might regulate expression of its transporters. •This information is beneficial for understanding the muscle remodeling by exercise. -- Abstract: We here investigated whether an acute bout of endurance exercise would induce the expression of amino acid transporters that regulate leucine transport across plasma and lysosomal membranes in rat skeletal muscle. Rats ran on a motor-driven treadmill at a speed of 28 m/min for 90 min. Immediately after the exercise, we observed that expression of mRNAs encoding L-type amino acid transporter 1 (LAT1) and CD98 was induced in the gastrocnemius, soleus, and extensor digitorum longus (EDL) muscles. Sodium-coupled neutral amino acid transporter 2 (SNAT2) mRNA was also induced by the exercise in those three muscles. Expression of proton-assisted amino acid transporter 1 (PAT1) mRNA was slightly but not significantly induced by a single bout of exercise in soleus and EDL muscles. Exercise-induced mRNA expression of these amino acid transporters appeared to be attenuated by repeated bouts of the exercise. These results suggested that the expression of amino acid transporters for leucine may be induced in response to an increase in the requirement for this amino acid in the cells of working skeletal muscles

  2. Altered myoplasmic Ca(2+) handling in rat fast-twitch skeletal muscle fibres during disuse atrophy.

    Science.gov (United States)

    Weiss, Norbert; Andrianjafiniony, Tina; Dupré-Aucouturier, Sylvie; Pouvreau, Sandrine; Desplanches, Dominique; Jacquemond, Vincent

    2010-03-01

    Calcium-dependent signalling pathways are believed to play an important role in skeletal muscle atrophy, but whether intracellular Ca(2+) homeostasis is affected in that situation remains obscure. We show here that there is a 20% atrophy of the fast-type flexor digitorum brevis (FDB) muscle in rats hind limb unloaded (HU) for 2 weeks, with no change in fibre type distribution. In voltage-clamp experiments, the amplitude of the slow Ca(2+) current was found similar in fibres from control and HU animals. In fibres loaded with the Ca(2+) dye indo-1, the value for the rate of [Ca(2+)] decay after the end of 5-100-ms-long voltage-clamp depolarisations from -80 to +10 mV was found to be 30-50% lower in fibres from HU animals. This effect was consistent with a reduced contribution of both saturable and non-saturable components of myoplasmic Ca(2+) removal. However, there was no change in the relative amount of parvalbumin, and type 1 sarco-endoplasmic reticulum Ca(2+)-ATPase was increased by a factor of three in the atrophied muscles. Confocal imaging of mitochondrial membrane potential showed that atrophied FDB fibres had significantly depolarized mitochondria as compared to control fibres. Depolarization of mitochondria in control fibres with carbonyl cyanide-p-trifluoromethoxyphenylhydrazone induced a slowing of the decay of [Ca(2+)] transients accompanied by an increase in resting [Ca(2+)] and a reduction of the peak amplitude of the transients. Overall results provide the first functional evidence for severely altered intracellular Ca(2+) removal capabilities in atrophied fast-type muscle fibres and highlight the possible contribution of reduced mitochondrial polarisation.

  3. Skeletal muscle action of estrogen receptor α is critical for the maintenance of mitochondrial function and metabolic homeostasis in females

    DEFF Research Database (Denmark)

    Ribas, Vicent; Drew, Brian G; Zhou, Zhenqi

    2016-01-01

    Impaired estrogen receptor α (ERα) action promotes obesity and metabolic dysfunction in humans and mice; however, the mechanisms underlying these phenotypes remain unknown. Considering that skeletal muscle is a primary tissue responsible for glucose disposal and oxidative metabolism, we establish...... of dysfunctional mitochondria in MERKO muscle and implicate ERα in the preservation of mitochondrial health and insulin sensitivity as a defense against metabolic disease in women....

  4. Exercise training and return to a well-balanced diet activate the neuregulin 1/ErbB pathway in skeletal muscle of obese rats

    Science.gov (United States)

    Ennequin, Gaël; Boisseau, Nathalie; Caillaud, Kevin; Chavanelle, Vivien; Gerbaix, Maude; Metz, Lore; Etienne, Monique; Walrand, Stéphane; Masgrau, Aurélie; Guillet, Christelle; Courteix, Daniel; Niu, Airu; Li, Yi-Ping; Capel, Fréderic; Sirvent, Pascal

    2015-01-01

    Some studies suggest that the signalling pathway of neuregulin 1 (NRG1), a protein involved in the regulation of skeletal muscle metabolism, could be altered by nutritional and exercise interventions. We hypothesized that diet-induced obesity could lead to alterations of the NRG1 signalling pathway and that chronic exercise could improve NRG1 signalling in rat skeletal muscle. To test this hypothesis, male Wistar rats received a high fat/high sucrose (HF/HS) diet for 16 weeks. At the end of this period, NRG1 and ErbB expression/activity in skeletal muscle was assessed. The obese rats then continued the HF/HS diet or were switched to a well-balanced diet. Moreover, in both groups, half of the animals also performed low intensity treadmill exercise training. After another 8 weeks, NRG1 and ErbB expression/activity in skeletal muscle were tested again. The 16 week HF/HS diet induced obesity, but did not significantly affect the NRG1/ErbB signalling pathway in rat skeletal muscle. Conversely, after the switch to a well-balanced diet, NRG1 cleavage ratio and ErbB4 amount were increased. Chronic exercise training also promoted NRG1 cleavage, resulting in increased ErbB4 phosphorylation. This result was associated with increased protein expression and phosphorylation ratio of the metalloprotease ADAM17, which is involved in NRG1 shedding. Similarly, in vitro stretch-induced activation of ADAM17 in rat myoblasts induced NRG1 cleavage and ErbB4 activation. These results show that low intensity endurance training and well-balanced diet activate the NRG1-ErbB4 pathway, possibly via the metalloprotease ADAM17, in skeletal muscle of diet-induced obese rats. PMID:25820551

  5. High Fat Diet-Induced Changes in Mouse Muscle Mitochondrial Phospholipids Do Not Impair Mitochondrial Respiration Despite Insulin Resistance

    Science.gov (United States)

    Hulshof, Martijn F. M.; van den Berg, Sjoerd A. A.; Schaart, Gert; van Dijk, Ko Willems; Smit, Egbert; Mariman, Edwin C. M.

    2011-01-01

    Background Type 2 diabetes mellitus and muscle insulin resistance have been associated with reduced capacity of skeletal muscle mitochondria, possibly as a result of increased intake of dietary fat. Here, we examined the hypothesis that a prolonged high-fat diet consumption (HFD) increases the saturation of muscle mitochondrial membrane phospholipids causing impaired mitochondrial oxidative capacity and possibly insulin resistance. Methodology C57BL/6J mice were fed an 8-week or 20-week low fat diet (10 kcal%; LFD) or HFD (45 kcal%). Skeletal muscle mitochondria were isolated and fatty acid (FA) composition of skeletal muscle mitochondrial phospholipids was analyzed by thin-layer chromatography followed by GC. High-resolution respirometry was used to assess oxidation of pyruvate and fatty acids by mitochondria. Insulin sensitivity was estimated by HOMA-IR. Principal Findings At 8 weeks, mono-unsaturated FA (16∶1n7, 18∶1n7 and 18∶1n9) were decreased (−4.0%, p<0.001), whereas saturated FA (16∶0) were increased (+3.2%, p<0.001) in phospholipids of HFD vs. LFD mitochondria. Interestingly, 20 weeks of HFD descreased mono-unsaturated FA while n-6 poly-unsaturated FA (18∶2n6, 20∶4n6, 22∶5n6) showed a pronounced increase (+4.0%, p<0.001). Despite increased saturation of muscle mitochondrial phospholipids after the 8-week HFD, mitochondrial oxidation of both pyruvate and fatty acids were similar between LFD and HFD mice. After 20 weeks of HFD, the increase in n-6 poly-unsaturated FA was accompanied by enhanced maximal capacity of the electron transport chain (+49%, p = 0.002) and a tendency for increased ADP-stimulated respiration, but only when fuelled by a lipid-derived substrate. Insulin sensitivity in HFD mice was reduced at both 8 and 20 weeks. Conclusions/Interpretation Our findings do not support the concept that prolonged HF feeding leads to increased saturation of skeletal muscle mitochondrial phospholipids resulting in a decrease in

  6. High fat diet-induced changes in mouse muscle mitochondrial phospholipids do not impair mitochondrial respiration despite insulin resistance.

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    Joris Hoeks

    Full Text Available BACKGROUND: Type 2 diabetes mellitus and muscle insulin resistance have been associated with reduced capacity of skeletal muscle mitochondria, possibly as a result of increased intake of dietary fat. Here, we examined the hypothesis that a prolonged high-fat diet consumption (HFD increases the saturation of muscle mitochondrial membrane phospholipids causing impaired mitochondrial oxidative capacity and possibly insulin resistance. METHODOLOGY: C57BL/6J mice were fed an 8-week or 20-week low fat diet (10 kcal%; LFD or HFD (45 kcal%. Skeletal muscle mitochondria were isolated and fatty acid (FA composition of skeletal muscle mitochondrial phospholipids was analyzed by thin-layer chromatography followed by GC. High-resolution respirometry was used to assess oxidation of pyruvate and fatty acids by mitochondria. Insulin sensitivity was estimated by HOMA-IR. PRINCIPAL FINDINGS: At 8 weeks, mono-unsaturated FA (16∶1n7, 18∶1n7 and 18∶1n9 were decreased (-4.0%, p<0.001, whereas saturated FA (16∶0 were increased (+3.2%, p<0.001 in phospholipids of HFD vs. LFD mitochondria. Interestingly, 20 weeks of HFD descreased mono-unsaturated FA while n-6 poly-unsaturated FA (18∶2n6, 20∶4n6, 22∶5n6 showed a pronounced increase (+4.0%, p<0.001. Despite increased saturation of muscle mitochondrial phospholipids after the 8-week HFD, mitochondrial oxidation of both pyruvate and fatty acids were similar between LFD and HFD mice. After 20 weeks of HFD, the increase in n-6 poly-unsaturated FA was accompanied by enhanced maximal capacity of the electron transport chain (+49%, p = 0.002 and a tendency for increased ADP-stimulated respiration, but only when fuelled by a lipid-derived substrate. Insulin sensitivity in HFD mice was reduced at both 8 and 20 weeks. CONCLUSIONS/INTERPRETATION: Our findings do not support the concept that prolonged HF feeding leads to increased saturation of skeletal muscle mitochondrial phospholipids resulting in a decrease in

  7. Overexpression of SMPX in adult skeletal muscle does not change skeletal muscle fiber type or size.

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    Einar Eftestøl

    Full Text Available Mechanical factors such as stretch are thought to be important in the regulation of muscle phenotype. Small muscle protein X-linked (SMPX is upregulated by stretch in skeletal muscle and has been suggested to serve both as a transcription factor and a mechanosensor, possibly giving rise to changes in both fiber size and fiber type. We have used in vivo confocal imaging to study the subcellular localization of SMPX in skeletal muscle fibers of adult rats using a SMPX-EGFP fusion protein. The fusion protein was localized predominantly in repetitive double stripes flanking the Z-disc, and was excluded from all nuclei. This localization would be consistent with SMPX being a mechanoreceptor, but not with SMPX playing a role as a transcription factor. In vivo overexpression of ectopic SMPX in skeletal muscle of adult mice gave no significant changes in fiber type distribution or cross sectional area, thus a role of SMPX in regulating muscle phenotype remains unclear.

  8. Effect of intermittent glutamine supplementation on skeletal muscle is not long-lasting in very old rats.

    Science.gov (United States)

    Meynial-Denis, D; Beaufrère, A-M; Mignon, M; Patureau Mirand, P

    2013-01-01

    Muscle is the major site for glutamine synthesis via glutamine synthetase (GS). This enzyme is increased 1.5-2 fold in 25-27-mo rats and may be a consequence of aging-induced stress. This stimulation is similar to the induction observed following a catabolic state such as glucocorticoid treatment (6 to 24 months). Although oral glutamine supply regulates the plasma glutamine level, nothing is known if this supplementation is interrupted before the experiment. Adult (8-mo) and very old (27-mo) female rats were exposed to intermittent glutamine supplementation for 50 % of their age lifetime. Treated rats received glutamine added to their drinking water and control rats water alone but the effect of glutamine supplementation was only studied 15 days after the last supplementation. Glutamine pretreatment discontinued 15 days before the experiment increased plasma glutamine to ~ 0.6 mM, a normal value in very old rats. However, it failed to decrease the up-regulated GS activity in skeletal muscle from very old rats. Our results suggest that long-term treatment with glutamine started before advanced age but discontinued 15 days before rat sacrifice is effective in increasing plasma glutamine to recover basal adult value and in maintaining plasma glutamine in very old rats, but has no long-lasting effect on the GS activity of skeletal muscle with advanced age.

  9. Cerium oxide nanozyme modulate the ‘exercise’ redox biology of skeletal muscle

    Science.gov (United States)

    Arya, Aditya; Sethy, Niroj Kumar; Gangwar, Anamika; Bhargava, Neelima; Dubey, Amarish; Roy, Manas; Srivastava, Gaurav; Singh, Sushil Kumar; Das, Mainak; Bhargava, Kalpana

    2017-05-01

    ‘Exercise’ is a double-edged sword for the skeletal muscle. Small amount of ROS generated during mild exercise, is essential for normal force generation; whereas large quantity of ROS generated during intense exercise, may cause contractile dysfunction, resulting in muscle weakness and fatigue. One of the key question in skeletal muscle physiology is ‘could antioxidant therapy improve the skeletal muscle endurance? A question, which has resulted in contradictory experimental findings till this date. This work has addressed this ‘very question’ using a synthetic, inorganic, antioxidant nano-material viz., ‘cerium oxide nanozyme’ (CON). It has been introduced in the rat by intramuscular injection, and the skeletal muscle endurance has been evaluated. Intramuscular injections of CON, concurrent with exercise, enhanced muscle mass, glycogen and ATP content, type I fiber ratio, thus resulting in significantly higher muscle endurance. Electron microscope studies confirmed the presence of CON in the vicinity of muscle mitochondria. There was an increase in the number and size of the muscle mitochondria in the CON treated muscle, following exercise, as compared to the untreated group with only exercised muscle. Quantitative proteomics data and subsequent biological network analysis studies, identified higher levels of oxidative phosphorylation, TCA cycle output and glycolysis in CON supplemented exercised muscle over only exercised muscle. This was further associated with significant increase in the mitochondrial respiratory capacity and muscle contraction, primarily due to higher levels of electron transport chain proteins like NDUFA9, SDHA, ATP5B and ATP5D, which were validated by real-time PCR and western blotting. Along with this, persistence of CON in muscle was evaluated with ICP-MS analysis, which revealed clearance of the particles after 90 d, without exhibiting any inflammation or adverse affects on the health of the experimental animals. Thus a

  10. Reduced expression of nuclear-encoded genes involved in mitochondrial oxidative metabolism in skeletal muscle of insulin-resistant women with polycystic ovary syndrome

    DEFF Research Database (Denmark)

    Skov, Vibe; Glintborg, Dorte; Knudsen, Steen

    2007-01-01

    Insulin resistance in skeletal muscle is a major risk factor for the development of type 2 diabetes in women with polycystic ovary syndrome (PCOS). In patients with type 2 diabetes, insulin resistance in skeletal muscle is associated with abnormalities in insulin signaling, fatty acid metabolism......, and mitochondrial oxidative phosphorylation (OXPHOS). In PCOS patients, the molecular mechanisms of insulin resistance are, however, less well characterized. To identify biological pathways of importance for the pathogenesis of insulin resistance in PCOS, we compared gene expression in skeletal muscle...... of metabolically characterized PCOS patients (n = 16) and healthy control subjects (n = 13) using two different approaches for global pathway analysis: gene set enrichment analysis (GSEA 1.0) and gene map annotator and pathway profiler (GenMAPP 2.0). We demonstrate that impaired insulin-stimulated total, oxidative...

  11. Estrogen supplementation failed to attenuate biochemical indices of neutrophil infiltration or damage in rat skeletal muscles following ischemia.

    Science.gov (United States)

    Tiidus, Peter M; Deller, Mirada; Bombardier, Eric; Gül, Mustafa; Liu, X Linda

    2005-01-01

    This study examined the effects of estrogen supplementation on markers of neutrophil infiltration and damage in skeletal muscle of rats following ischemia. Male and female gonad-intact rats, with or without 14 days of estrogen supplementation were subjected to two hours of hind-limb ischemia and sacrificed at 24, 48 or 72 hours post-ischemia. Control animals were sacrificed without ischemia. Plantaris and red and white gastrocneimus muscles were removed and assayed for myeloperoxidase (MPO), a marker of neutrophil infiltration, and glucose-6-phosphate dehydrogenase (G6PD) and beta-glucuronidase (betaGLU), as markers of muscle damage. Significant elevations of MPO, G6PD and betaGLU activities were observed at various time points post-ischemia. No systematic differences between genders were noted in any of the measures. Estrogen supplementation in both male and female animals failed to significantly attenuate post-ischemia increases in MPO, G6PD and betaGLU activities in any of the muscles studied and in some cases accentuated activities of some of these measures. Unlike previous findings following exercise in skeletal muscle, this study failed to demonstrate estrogen-induced attenuation of indices of neutrophil infiltration or damage in skeletal muscles of rats up to 72 hours following ischemia. This demonstrates that estrogen may not consistently attenuate neutrophil infiltration and that a number of variables including damage modality, tissue or estrogen level may influence this.

  12. Estrogen supplementation failed to attenuate biochemical indices of neutrophil infiltration or damage in rat skeletal muscles following ischemia

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    PETER M TIIDUS

    2005-01-01

    Full Text Available This study examined the effects of estrogen supplementation on markers of neutrophil infiltration and damage in skeletal muscle of rats following ischemia. Male and female gonad-intact rats, with or without 14 days of estrogen supplementation were subjected to two hours of hind-limb ischemia and sacrificed at 24, 48 or 72 hours post-ischemia. Control animals were sacrificed without ischemia. Plantaris and red and white gastrocneimus muscles were removed and assayed for myeloperoxidase (MPO, a marker of neutrophil infiltration, and glucose-6-phosphate dehydrogenase (G6PD and ß-glucuronidase (GLU, as markers of muscle damage. Significant elevations of MPO, G6PD and GLU activities were observed at various time points post-ischemia. No systematic differences between genders were noted in any of the measures. Estrogen supplementation in both male and female animals failed to significantly attenuate post-ischemia increases in MPO, G6PD and GLU activities in any of the muscles studied and in some cases accentuated activities of some of these measures. Unlike previous findings following exercise in skeletal muscle, this study failed to demonstrate estrogen-induced attenuation of indices of neutrophil infiltration or damage in skeletal muscles of rats up to 72 hours following ischemia. This demonstrates that estrogen may not consistently attenuate neutrophil infiltration and that a number of variables including damage modality, tissue or estrogen level may influence this.

  13. Fructose overfeeding in first-degree relatives of type 2 diabetic patients impacts energy metabolism and mitochondrial functions in skeletal muscle.

    Science.gov (United States)

    Seyssel, Kevin; Meugnier, Emmanuelle; Lê, Kim-Anne; Durand, Christine; Disse, Emmanuel; Blond, Emilie; Pays, Laurent; Nataf, Serge; Brozek, John; Vidal, Hubert; Tappy, Luc; Laville, Martine

    2016-12-01

    The aim of the study was to assess the effects of a high-fructose diet (HFrD) on skeletal muscle transcriptomic response in healthy offspring of patients with type 2 diabetes, a subgroup of individuals prone to metabolic disorders. Ten healthy normal weight first-degree relatives of type 2 diabetic patients were submitted to a HFrD (+3.5 g fructose/kg fat-free mass per day) during 7 days. A global transcriptomic analysis was performed on skeletal muscle biopsies combined with in vitro experiments using primary myotubes. Transcriptomic analysis highlighted profound effects on fatty acid oxidation and mitochondrial pathways supporting the whole-body metabolic shift with the preferential use of carbohydrates instead of lipids. Bioinformatics tools pointed out possible transcription factors orchestrating this genomic regulation, such as PPARα and NR4A2. In vitro experiments in human myotubes suggested an indirect action of fructose in skeletal muscle, which seemed to be independent from lactate, uric acid, or nitric oxide. This study shows therefore that a large cluster of genes related to energy metabolism, mitochondrial function, and lipid oxidation was downregulated after 7 days of HFrD, thus supporting the concept that overconsumption of fructose-containing foods could contribute to metabolic deterioration in humans. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. PGC-1alpha is required for training-induced prevention of age-associated decline in mitochondrial enzymes in mouse skeletal muscle

    DEFF Research Database (Denmark)

    Leick, Lotte; Lyngby, Stine Secher; Wojtaszewski, Jørgen

    2010-01-01

    The aim of the present study was to test the hypothesis that exercise training prevents an age-associated decline in skeletal muscle mitochondrial enzymes through a PGC-1alpha dependent mechanism. Whole body PGC-1alpha knock-out (KO) and littermate wildtype (WT) mice were submitted to long term...

  15. Amla Enhances Mitochondrial Spare Respiratory Capacity by Increasing Mitochondrial Biogenesis and Antioxidant Systems in a Murine Skeletal Muscle Cell Line

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    Hirotaka Yamamoto

    2016-01-01

    Full Text Available Amla is one of the most important plants in Indian traditional medicine and has been shown to improve various age-related disorders while decreasing oxidative stress. Mitochondrial dysfunction is a proposed cause of aging through elevated oxidative stress. In this study, we investigated the effects of Amla on mitochondrial function in C2C12 myotubes, a murine skeletal muscle cell model with abundant mitochondria. Based on cell flux analysis, treatment with an extract of Amla fruit enhanced mitochondrial spare respiratory capacity, which enables cells to overcome various stresses. To further explore the mechanisms underlying these effects on mitochondrial function, we analyzed mitochondrial biogenesis and antioxidant systems, both proposed regulators of mitochondrial spare respiratory capacity. We found that Amla treatment stimulated both systems accompanied by AMPK and Nrf2 activation. Furthermore, we found that Amla treatment exhibited cytoprotective effects and lowered reactive oxygen species (ROS levels in cells subjected to t-BHP-induced oxidative stress. These effects were accompanied by increased oxygen consumption, suggesting that Amla protected cells against oxidative stress by using enhanced spare respiratory capacity to produce more energy. Thus we identified protective effects of Amla, involving activation of mitochondrial function, which potentially explain its various effects on age-related disorders.

  16. Ammonia lowering reverses sarcopenia of cirrhosis by restoring skeletal muscle proteostasis.

    Science.gov (United States)

    Kumar, Avinash; Davuluri, Gangarao; Silva, Rafaella Nascimento E; Engelen, Marielle P K J; Ten Have, Gabrie A M; Prayson, Richard; Deutz, Nicolaas E P; Dasarathy, Srinivasan

    2017-06-01

    Sarcopenia or skeletal muscle loss is a frequent, potentially reversible complication in cirrhosis that adversely affects clinical outcomes. Hyperammonemia is a consistent abnormality in cirrhosis that results in impaired skeletal muscle protein synthesis and breakdown (proteostasis). Despite the availability of effective ammonia-lowering therapies, whether lowering ammonia restores proteostasis and increases muscle mass is unknown. Myotube diameter, protein synthesis, and molecular responses in C2C12 murine myotubes to withdrawal of ammonium acetate following 24-hour exposure to 10 mM ammonium acetate were complemented by in vivo studies in the hyperammonemic portacaval anastomosis rat and sham-operated, pair-fed Sprague-Dawley rats treated with ammonia-lowering therapy by l-ornithine l-aspartate and rifaximin orally for 4 weeks. We observed reduced myotube diameter, impaired protein synthesis, and increased autophagy flux in response to hyperammonemia, which were partially reversed following 24-hour and 48-hour withdrawal of ammonium acetate. Consistently, 4 weeks of ammonia-lowering therapy resulted in significant lowering of blood and skeletal muscle ammonia, increase in lean body mass, improved grip strength, higher skeletal muscle mass and diameter, and an increase in type 2 fibers in treated compared to untreated portacaval anastomosis rats. The increased skeletal muscle myostatin expression, reduced mammalian target of rapamycin complex 1 function, and hyperammonemic stress response including autophagy markers normally found in portacaval anastomosis rats were reversed by treatment with ammonia-lowering therapy. Despite significant improvement, molecular and functional readouts were not completely reversed by ammonia-lowering measures. Ammonia-lowering therapy results in improvement in skeletal muscle phenotype and function and molecular perturbations of hyperammonemia; these preclinical studies complement previous studies on ammonia-induced skeletal muscle

  17. Localization of 3H-diethylstilbestrol in skeletal muscle

    International Nuclear Information System (INIS)

    Gruber, B.; Cohen, L.

    1981-01-01

    The localization of diethylstilbestrol (DES) in skeletal muscle was studied in CF1 mice and perfused rat hindlimbs. There was a slow accumulation of 3H-DES in mouse muscle from 4 to 24 hours following i.p. injection even though plasma DES was decreasing. Twenty-four hours after injection of 50 microCi 3H-DES (714 pmole) mouse gastrocnemius contained 8.9 x 10(-17) mole unaltered 3H-DES per mg muscle. Extrapolating to the entire skeletal muscle mass of the animal, this represents 0.15% of the radioactivity injected. The radioactivity in muscle was completely extracted with 95% ethanol or ether: ethanol (3:1), and both unaltered DES and DES-metabolites were present in the extracts. The fraction of radioactivity due to unaltered DES 4 hours after injection was 0.51 +/- 0.09 in muscle and 0.30 +/- 0.11 in plasma. Significant extrahepatic metabolism of DES was demonstrated in perfused isolated rat hindlimbs by the presence of DES-metabolites in the perfusate. The radioactivity extracted from the perfused muscle itself was unaltered DES. These results indicate that skeletal muscle is an important site of DES localization in rodents

  18. Beneficial Autophagic Activities, Mitochondrial Function, and Metabolic Phenotype Adaptations Promoted by High-Intensity Interval Training in a Rat Model

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    Fang-Hui Li

    2018-05-01

    Full Text Available The effects of high-intensity interval (HIIT and moderate-intensity continuous training (MICT on basal autophagy and mitochondrial function in cardiac and skeletal muscle and plasma metabolic phenotypes have not been clearly characterized. Here, we investigated how 10-weeks HIIT and MICT differentially modify basal autophagy and mitochondrial markers in cardiac and skeletal muscle and conducted an untargeted metabolomics study with proton nuclear magnetic resonance (1H NMR spectroscopy and multivariate statistical analysis of plasma metabolic phenotypes. Male Sprague–Dawley rats were separated into three groups: sedentary control (SED, MICT, and HIIT. Rats underwent evaluation of exercise performance, including exercise tolerance and grip strength, and blood lactate levels were measured immediately after an incremental exercise test. Plasma samples were analyzed by 1H NMR. The expression of autophagy and mitochondrial markers and autophagic flux (LC3II/LC3-I ratio in cardiac, rectus femoris, and soleus muscle were analyzed by western blotting. Time to exhaustion and grip strength increased significantly following HIIT compared with that in both SED and MICT groups. Compared with those in the SED group, blood lactate level, and the expression of SDH, COX-IV, and SIRT3 significantly increased in rectus femoris and soleus muscle of both HIIT and MICT groups. Meanwhile, SDH and COX-IV content of cardiac muscle and COX-IV and SIRT3 content of rectus femoris and soleus muscle increased significantly following HIIT compared with that following MICT. The expression of LC3-II, ATG-3, and Beclin-1 and LC3II/LC3-I ratio were significantly increased only in soleus and cardiac muscle following HIIT. These data indicate that HIIT was more effective for improving physical performance and facilitating cardiac and skeletal muscle adaptations that increase mitochondrial function and basal autophagic activities. Moreover, 1H NMR spectroscopy and multivariate

  19. Beneficial Autophagic Activities, Mitochondrial Function, and Metabolic Phenotype Adaptations Promoted by High-Intensity Interval Training in a Rat Model.

    Science.gov (United States)

    Li, Fang-Hui; Li, Tao; Ai, Jing-Yi; Sun, Lei; Min, Zhu; Duan, Rui; Zhu, Ling; Liu, Yan-Ying; Liu, Timon Cheng-Yi

    2018-01-01

    The effects of high-intensity interval (HIIT) and moderate-intensity continuous training (MICT) on basal autophagy and mitochondrial function in cardiac and skeletal muscle and plasma metabolic phenotypes have not been clearly characterized. Here, we investigated how 10-weeks HIIT and MICT differentially modify basal autophagy and mitochondrial markers in cardiac and skeletal muscle and conducted an untargeted metabolomics study with proton nuclear magnetic resonance ( 1 H NMR) spectroscopy and multivariate statistical analysis of plasma metabolic phenotypes. Male Sprague-Dawley rats were separated into three groups: sedentary control (SED), MICT, and HIIT. Rats underwent evaluation of exercise performance, including exercise tolerance and grip strength, and blood lactate levels were measured immediately after an incremental exercise test. Plasma samples were analyzed by 1 H NMR. The expression of autophagy and mitochondrial markers and autophagic flux (LC3II/LC3-I ratio) in cardiac, rectus femoris, and soleus muscle were analyzed by western blotting. Time to exhaustion and grip strength increased significantly following HIIT compared with that in both SED and MICT groups. Compared with those in the SED group, blood lactate level, and the expression of SDH, COX-IV, and SIRT3 significantly increased in rectus femoris and soleus muscle of both HIIT and MICT groups. Meanwhile, SDH and COX-IV content of cardiac muscle and COX-IV and SIRT3 content of rectus femoris and soleus muscle increased significantly following HIIT compared with that following MICT. The expression of LC3-II, ATG-3, and Beclin-1 and LC3II/LC3-I ratio were significantly increased only in soleus and cardiac muscle following HIIT. These data indicate that HIIT was more effective for improving physical performance and facilitating cardiac and skeletal muscle adaptations that increase mitochondrial function and basal autophagic activities. Moreover, 1 H NMR spectroscopy and multivariate statistical

  20. Increased intrinsic mitochondrial respiratory capacity in skeletal muscle from rats with streptozotocin-induced hyperglycemia

    DEFF Research Database (Denmark)

    Larsen, Steen; Scheede-Bergdahl, Celena; Whitesell, Thomas

    2015-01-01

    the groups when evaluating the more physiol. complex I and II linked OXPHOS capacity. These findings indicate that chronic hyperglycemia results in an elevated intrinsic mitochondrial respiratory capacity in both soleus and, at varying degree, plantaris muscle, findings that are consistent with human T1DM...

  1. NAD+/NADH and skeletal muscle mitochondrial adaptations to exercise

    Science.gov (United States)

    White, Amanda T.

    2012-01-01

    The pyridine nucleotides, NAD+ and NADH, are coenzymes that provide oxidoreductive power for the generation of ATP by mitochondria. In skeletal muscle, exercise perturbs the levels of NAD+, NADH, and consequently, the NAD+/NADH ratio, and initial research in this area focused on the contribution of redox control to ATP production. More recently, numerous signaling pathways that are sensitive to perturbations in NAD+(H) have come to the fore, as has an appreciation for the potential importance of compartmentation of NAD+(H) metabolism and its subsequent effects on various signaling pathways. These pathways, which include the sirtuin (SIRT) proteins SIRT1 and SIRT3, the poly(ADP-ribose) polymerase (PARP) proteins PARP1 and PARP2, and COOH-terminal binding protein (CtBP), are of particular interest because they potentially link changes in cellular redox state to both immediate, metabolic-related changes and transcriptional adaptations to exercise. In this review, we discuss what is known, and not known, about the contribution of NAD+(H) metabolism and these aforementioned proteins to mitochondrial adaptations to acute and chronic endurance exercise. PMID:22436696

  2. Rate equation for creatine kinase predicts the in vivo reaction velocity: 31P NMR surface coil studies in brain, heart, and skeletal muscle of the living rat

    International Nuclear Information System (INIS)

    Bittl, J.A.; DeLayre, J.; Ingwall, J.S.

    1987-01-01

    Brain, heart, and skeletal muscle contain four different creatine kinase isozymes and various concentrations of substrates for the creatine kinase reaction. To identify if the velocity of the creatine kinase reaction under cellular conditions is regulated by enzyme activity and substrate concentrations as predicted by the rate equation, the authors used 31 P NMR and spectrophotometric techniques to measure reaction velocity, enzyme content, isozyme distribution, and concentrations of substrates in brain, heart, and skeletal muscle of living rat under basal or resting conditions. The total tissue activity of creatine kinase in the direction of MgATP synthesis provided an estimate for V/sub max/ and exceeded the NMR-determined in vivo reaction velocities by an order of magnitude. The isozyme composition varied among the three tissues: >99% BB for brain; 14% MB, 61% MM, and 25% mitochondrial for heart; and 98% MM and 2% mitochondrial for skeletal muscle. The NMR-determined reaction velocities agreed with predicted values from the creatine kinase rate equation. The concentrations of free creatine and cytosolic MgADP, being less than or equal to the dissociation constants for each isozyme, were dominant terms in the creatine kinase rate equation for predicting the in vivo reaction velocity. Thus, they observed that the velocity of the creatine kinase reaction is regulated by total tissue enzyme activity and by the concentrations of creatine and MgADP in a manner that is independent of isozyme distribution

  3. Proteomic profiling of non-obese type 2 diabetic skeletal muscle.

    Science.gov (United States)

    Mullen, Edel; Ohlendieck, Kay

    2010-03-01

    Abnormal glucose handling has emerged as a major clinical problem in millions of diabetic patients worldwide. Insulin resistance affects especially one of the main target organs of this hormone, the skeletal musculature, making impaired glucose metabolism in contractile fibres a major feature of type 2 diabetes. High levels of circulating free fatty acids, an increased intramyocellular lipid content, impaired insulin-mediated glucose uptake, diminished mitochondrial functioning and an overall weakened metabolic flexibility are pathobiochemical hallmarks of diabetic skeletal muscles. In order to increase our cellular understanding of the molecular mechanisms that underlie this complex diabetes-associated skeletal muscle pathology, we initiated herein a mass spectrometry-based proteomic analysis of skeletal muscle preparations from the non-obese Goto-Kakizaki rat model of type 2 diabetes. Following staining of high-resolution two-dimensional gels with colloidal Coomassie Blue, 929 protein spots were detected, whereby 21 proteins showed a moderate differential expression pattern. Decreased proteins included carbonic anhydrase, 3-hydroxyisobutyrate dehydrogenase and enolase. Increased proteins were identified as monoglyceride lipase, adenylate kinase, Cu/Zn superoxide dismutase, phosphoglucomutase, aldolase, isocitrate dehydrogenase, cytochrome c oxidase, small heat shock Hsp27/B1, actin and 3-mercaptopyruvate sulfurtransferase. These proteomic findings suggest that the diabetic phenotype is associated with a generally perturbed protein expression pattern, affecting especially glucose, fatty acid, nucleotide and amino acid metabolism, as well as the contractile apparatus, the cellular stress response, the anti-oxidant defense system and detoxification mechanisms. The altered expression levels of distinct skeletal muscle proteins, as documented in this study, might be helpful for the future establishment of a comprehensive biomarker signature of type 2 diabetes

  4. Branched Chain Amino Acid Oxidation in Cultured Rat Skeletal Muscle Cells

    Science.gov (United States)

    Pardridge, William M.; Casanello-Ertl, Delia; Duducgian-Vartavarian, Luiza

    1980-01-01

    Leucine metabolism in skeletal muscle is linked to protein turnover. Since clofibrate is known both to cause myopathy and to decrease muscle protein content, the present investigations were designed to examine the effects of acute clofibrate treatment on leucine oxidation. Rat skeletal muscle cells in tissue culture were used in these studies because cultivated skeletal muscle cells, like muscle in vivo, have been shown to actively utilize branched chain amino acids and to produce alanine. The conversion of [1-14C]leucine to 14CO2 or to the [1-14C]keto-acid of leucine (α-keto-isocaproate) was linear for at least 2 h of incubation; the production of 14CO2 from [1-14C]leucine was saturable with a Km = 6.3 mM and a maximum oxidation rate (Vmax) = 31 nmol/mg protein per 120 min. Clofibric acid selectively inhibited the oxidation of [1-14C]leucine (Ki = 0.85 mM) and [U-14C]isoleucine, but had no effect on the oxidation of [U-14C]glutamate, -alanine, -lactate, or -palmitate. The inhibition of [1-14C]leucine oxidation by clofibrate was also observed in the rat quarter-diaphragm preparation. Clofibrate primarily inhibited the production of 14CO2 and had relatively little effect on the production of [1-14C]keto-acid of leucine. A physiological concentration—3.0 g/100 ml—of albumin, which actively binds clofibric acid, inhibited but did not abolish the effects of a 2-mM concentration of clofibric acid on leucine oxidation. Clofibrate treatment stimulated the net consumption of pyruvate, and inhibited the net production of alanine. The drug also increased the cytosolic NADH/NAD+ ratio as reflected by an increase in the lactate/pyruvate ratio, in association with a decrease in cell aspartate levels. The changes in pyruvate metabolism and cell redox state induced by the drug were delayed compared with the nearly immediate inhibition of leucine oxidation. These studies suggest that clofibric acid, in concentrations that approximate high therapeutic levels of the drug

  5. Formation of hydrogen peroxide and nitric oxide in rat skeletal muscle cells during contractions

    DEFF Research Database (Denmark)

    Silveira, Leonardo R.; Pereira-Da-Silva, Lucia; Juel, Carsten

    2003-01-01

    We examined intra- and extracellular H(2)O(2) and NO formation during contractions in primary rat skeletal muscle cell culture. The fluorescent probes DCFH-DA/DCFH (2,7-dichlorofluorescein-diacetate/2,7-dichlorofluorescein) and DAF-2-DA/DAF-2 (4,5-diaminofluorescein-diacetate/4,5-diaminofluoresce...

  6. Barium-induced skeletal muscle paralysis in the rat, and its relationship to human familial periodic paralysis

    Science.gov (United States)

    Schott, G. D.; McArdle, B.

    1974-01-01

    An in vivo study of skeletal muscle paralysis induced by intravenous barium chloride has been made in curarized and non-curarized rats. The influence of potassium and calcium chlorides, propranolol, ouabain, and prior adrenalectomy on the paralysis has also been studied. Paralysis is found to be due to a direct effect on skeletal muscle, and to correlate well with the development of hypokalaemia. Possible mechanisms of action of barium are discussed, and attention is drawn to the similarity between barium poisoning and hypokalaemic familial periodic paralysis. PMID:4813426

  7. The Emerging Role of Skeletal Muscle Metabolism as a Biological Target and Cellular Regulator of Cancer-Induced Muscle Wasting

    Science.gov (United States)

    Carson, James A.; Hardee, Justin P.; VanderVeen, Brandon N.

    2015-01-01

    While skeletal muscle mass is an established primary outcome related to understanding cancer cachexia mechanisms, considerable gaps exist in our understanding of muscle biochemical and functional properties that have recognized roles in systemic health. Skeletal muscle quality is a classification beyond mass, and is aligned with muscle’s metabolic capacity and substrate utilization flexibility. This supplies an additional role for the mitochondria in cancer-induced muscle wasting. While the historical assessment of mitochondria content and function during cancer-induced muscle loss was closely aligned with energy flux and wasting susceptibility, this understanding has expanded to link mitochondria dysfunction to cellular processes regulating myofiber wasting. The primary objective of this article is to highlight muscle mitochondria and oxidative metabolism as a biological target of cancer cachexia and also as a cellular regulator of cancer-induced muscle wasting. Initially, we examine the role of muscle metabolic phenotype and mitochondria content in cancer-induced wasting susceptibility. We then assess the evidence for cancer-induced regulation of skeletal muscle mitochondrial biogenesis, dynamics, mitophagy, and oxidative stress. In addition, we discuss environments associated with cancer cachexia that can impact the regulation of skeletal muscle oxidative metabolism. The article also examines the role of cytokine-mediated regulation of mitochondria function regulation, followed by the potential role of cancer-induced hypogonadism. Lastly, a role for decreased muscle use in cancer-induced mitochondrial dysfunction is reviewed. PMID:26593326

  8. Insulin resistance and mitochondrial function in skeletal muscle

    DEFF Research Database (Denmark)

    Dela, Flemming; Helge, Jørn Wulff

    2013-01-01

    are used in the attempt to resolve the mechanisms of insulin resistance. In this context, a dysfunction of mitochondria in the skeletal muscle has been suggested to play a pivotal role. It has been postulated that a decrease in the content of mitochondria in the skeletal muscle can explain the insulin...... resistance. Complementary to this also specific defects of components in the respiratory chain in the mitochondria have been suggested to play a role in insulin resistance. A key element in these mechanistic suggestions is inability to handle substrate fluxes and subsequently an accumulation of ectopic...... intramyocellular lipids, interfering with insulin signaling. In this review we will present the prevailing view-points and argue for the unlikelihood of this scenario being instrumental in human insulin resistance. This article is part of a Directed Issue entitled: Bioenergetic dysfunction....

  9. Myofibril ATPase activity of cardiac and skeletal muscle of exhaustively exercised rats.

    Science.gov (United States)

    Belcastro, A N; Turcotte, R; Rossiter, M; Secord, D; Maybank, P E

    1984-01-01

    The activation characteristics of Mg-ATP and Ca2+ on cardiac and skeletal muscle myofibril ATPase activity were studied in rats following a run to exhaustion. In addition, the effect of varying ionic strength was determined on skeletal muscle from exhausted animals. The exhausted group (E) ran at a speed of 25 m min-1 with an 8% incline. Myofibril ATPase activities for control (C) and E were determined with 1, 3 and 5 mM Mg-ATP and 1 and 10 microM Ca2+ at pH 7.0 and 30 degrees C. For control skeletal muscle, at 1 and 10 microM Ca2+, there was an increase in ATPase activity from 1 to 5 mM Mg-ATP (P less than 0.05). For E animals the myofibril ATPase activities at 10 microM Ca2+ and all Mg-ATP concentrations were similar to C (P greater than 0.05). At 1.0 microM Ca2+ and all Mg-ATP concentrations were similar to C (P greater than 0.05). At 1.0 microM Ca2+ the activities at 3 and 5 mM Mg-ATP were greater for the E animals (P less than 0.05). Increasing KCl concentrations resulted in greater inhibition for E animals. With cardiac muscle, the myofibril ATPase activities at 1.0 microM free Ca2+ were lower for E at all Mg-ATP levels (P less than 0.05). In contrast, at 10 microM Ca2+, the E group exhibited an elevated myofibril ATPase activity. The results indicate that Mg-ATP and Ca2+ activation of cardiac and skeletal muscle myofibril ATPase is altered with exhaustive exercise.

  10. Colchicine protects rat skeletal muscle from ischemia/reperfusion injury by suppressing oxidative stress and inflammation

    Directory of Open Access Journals (Sweden)

    Liangrong Wang

    2016-06-01

    Full Text Available Objective(s: Neutrophils play an important role in ischemia/reperfusion (IR induced skeletal muscle injury. Microtubules are required for neutrophil activation in response to various stimuli. This study aimed to investigate the effects of colchicine, a microtubule-disrupting agent, on skeletal muscle IR injury in a rat hindlimb ischemia model. Materials and Methods: Twenty-one Sprague-Dawley rats were randomly allocated into three groups: IR group, colchicine treated-IR (CO group and sham operation (SM group. Rats of both the IR and CO groups were subjected to 3 hr of ischemia by clamping the right femoral artery followed by 2 hr of reperfusion. Colchicine (1 mg/kg was administrated intraperitoneally prior to hindlimb ischemia in the CO group. After 2 hr of reperfusion, we measured superoxide dismutase (SOD and myeloperoxidase (MPO activities, and malondialdehyde (MDA, tumor necrosis factor (TNF-α and interleukin (IL-1β levels in the muscle samples. Plasma creatinine kinase (CK and lactate dehydrogenase (LDH levels were measured. We also evaluated the histological damage score and wet/dry weight (W/D ratio. Results: The histological damage score, W/D ratio, MPO activity, MDA, TNF-α and IL-1β levels in muscle tissues were significantly increased, SOD activity was decreased, and plasma CK and LDH levels were remarkably elevated in both the IR and CO groups compared to the SM group (P

  11. Proximal Neuropathy and Associated Skeletal Muscle Changes Resembling Denervation Atrophy in Hindlimbs of Chronic Hypoglycaemic Rats

    DEFF Research Database (Denmark)

    Jensen, Vivi F.H.; Molck, Anne Marie; Soeborg, Henrik

    2017-01-01

    Peripheral neuropathy is one of the most common complications of diabetic hyperglycaemia. Insulin-induced hypoglycaemia (IIH) might potentially exacerbate or contribute to neuropathy as hypoglycaemia also causes peripheral neuropathy. In rats, IIH induces neuropathy associated with skeletal muscle......, and severity of the myofibre atrophy correlated with severity of axonal degeneration in sciatic nerve. Both neuropathy and myopathy were still present after four weeks of recovery, although the neuropathy was less severe. In conclusion, the results suggest that peripheral neuropathy induced by IIH progresses...... changes. Aims of this study were to investigate the progression and sequence of histopathologic changes caused by chronic IIH in rat peripheral nerves and skeletal muscle, and whether such changes were reversible. Chronic IIH was induced by infusion of human insulin, followed by an infusion-free recovery...

  12. Proximal Neuropathy and Associated Skeletal Muscle Changes Resembling Denervation Atrophy in Hindlimbs of Chronic Hypoglycaemic Rats

    DEFF Research Database (Denmark)

    Jensen, Vivi F.H.; Molck, Anne Marie; Soeborg, Henrik

    2018-01-01

    Peripheral neuropathy is one of the most common complications of diabetic hyperglycaemia. Insulin-induced hypoglycaemia (IIH) might potentially exacerbate or contribute to neuropathy as hypoglycaemia also causes peripheral neuropathy. In rats, IIH induces neuropathy associated with skeletal muscle......, and severity of the myofibre atrophy correlated with severity of axonal degeneration in sciatic nerve. Both neuropathy and myopathy were still present after four weeks of recovery, although the neuropathy was less severe. In conclusion, the results suggest that peripheral neuropathy induced by IIH progresses...... changes. Aims of this study were to investigate the progression and sequence of histopathologic changes caused by chronic IIH in rat peripheral nerves and skeletal muscle, and whether such changes were reversible. Chronic IIH was induced by infusion of human insulin, followed by an infusion-free recovery...

  13. Pyruvate carboxylase is expressed in human skeletal muscle

    DEFF Research Database (Denmark)

    Minet, Ariane D; Gaster, Michael

    2010-01-01

    Pyruvate carboxylase (PC) is a mitochondrial enzyme that catalyses the carboxylation of pyruvate to oxaloacetate thereby allowing supplementation of citric acid cycle intermediates. The presence of PC in skeletal muscle is controversial. We report here, that PC protein is easily detectable...

  14. Sildenafil citrate protects skeletal muscle of ischemia-reperfusion injury: immunohistochemical study in rat model

    Directory of Open Access Journals (Sweden)

    Dinani Matoso Fialho de Oliveira Armstrong

    2013-04-01

    Full Text Available PURPOSE: To investigate the effect of sildenafil citrate (SC on skeletal muscle ischemia-reperfusion (IR injury in rats. METHODS: Adult male Wistar rats were randomized into three groups: vehicle-treated control (CTG, sildenafil citrate-treated (SCG, and sham group (SG. CTG and SCG had femoral artery occluded for 6 hours. Saline or 1 mg/kg of SC was given 5.5 hours after occlusion. SG had a similar procedure without artery occlusion. Soleus muscle samples were acquired 4 or 24h after the reperfusion. Immunohistochemistry caspase-3 analysis was used to estimate apoptosis using the apoptotic ratio (computed as positive/negative cells. Wilcoxon rank-sum or Kruskal-Wallis tests were used to assess differences among groups. RESULTS: Eighteen animals were included in the 4h reperfusion groups and 21 animals in the 24h reperfusion groups. The mean apoptotic ratio was 0.18±0.1 for the total cohort; 0.14±0.06 for the 4h reperfusion groups and 0.19±0.08 for the 24h groups (p<0.05. The SCG had lower caspase-3 ratio compared to the control groups at the 24h reperfusion time point (p<0.05. CONCLUSION: Sildenafil citrate administration after the onset of the ischemic injury reduces IR-induced cellular damage in skeletal muscle in this rat hindlimb ischemia model.

  15. Arginase promotes skeletal muscle arteriolar endothelial dysfunction in diabetic rats.

    Directory of Open Access Journals (Sweden)

    Fruzsina K. Johnson

    2013-05-01

    Full Text Available Endothelial dysfunction is a characteristic feature in diabetes that contributes to the development of vascular disease. Recently, arginase has been implicated in triggering endothelial dysfunction in diabetic patients and animals by competing with endothelial nitric oxide synthase for substrate L-arginine. While most studies have focused on the coronary circulation and large conduit blood vessels, the role of arginase in mediating diabetic endothelial dysfunction in other vascular beds has not been fully investigated. In the present study, we determined whether arginase contributes to endothelial dysfunction in skeletal muscle arterioles of diabetic rats. Diabetes was induced in male Sprague Dawley rats by streptozotocin injection. Four weeks after streptozotocin administration, blood glucose, glycated hemoglobin, and vascular arginase activity were significantly increased. In addition, a significant increase in arginase I and II mRNA expression was detected in gracilis muscle arterioles of diabetic rats compared to age-matched, vehicle control animals. To examine endothelial function, first-order gracilis muscle arterioles were isolated, cannulated in a pressure myograph system, exposed to graded levels of luminal flow, and internal vessel diameter measured. Increases in luminal flow (0-50µL/min caused progressive vasodilation in arterioles isolated from control, normoglycemic animals. However, flow-induced vasodilation was absent in arterioles obtained from streptozotocin-treated rats. Acute in-vitro pretreatment of blood vessels with the arginase inhibitors Nω-hydroxy-nor-L-arginine or S-(2-boronoethyl-L-cysteine restored flow-induced responses in arterioles from diabetic rats and abolished differences between diabetic and control animals. Similarly, acute in-vitro pretreatment with L-arginine returned flow-mediated vasodilation in vessels from diabetic animals to that of control rats. In contrast, D-arginine failed to restore flow

  16. Defects in mitochondrial ATP synthesis in dystrophin-deficient mdx skeletal muscles may be caused by complex I insufficiency.

    Directory of Open Access Journals (Sweden)

    Emma Rybalka

    Full Text Available Duchenne Muscular Dystrophy is a chronic, progressive and ultimately fatal skeletal muscle wasting disease characterised by sarcolemmal fragility and intracellular Ca2+ dysregulation secondary to the absence of dystrophin. Mounting literature also suggests that the dysfunction of key energy systems within the muscle may contribute to pathological muscle wasting by reducing ATP availability to Ca2+ regulation and fibre regeneration. No study to date has biochemically quantified and contrasted mitochondrial ATP production capacity by dystrophic mitochondria isolated from their pathophysiological environment such to determine whether mitochondria are indeed capable of meeting this heightened cellular ATP demand, or examined the effects of an increasing extramitochondrial Ca2+ environment. Using isolated mitochondria from the diaphragm and tibialis anterior of 12 week-old dystrophin-deficient mdx and healthy control mice (C57BL10/ScSn we have demonstrated severely depressed Complex I-mediated mitochondrial ATP production rate in mdx mitochondria that occurs irrespective of the macronutrient-derivative substrate combination fed into the Kreb's cycle, and, which is partially, but significantly, ameliorated by inhibition of Complex I with rotenone and stimulation of Complex II-mediated ATP-production with succinate. There was no difference in the MAPR response of mdx mitochondria to increasing extramitochondrial Ca2+ load in comparison to controls, and 400 nM extramitochondrial Ca2+ was generally shown to be inhibitory to MAPR in both groups. Our data suggests that DMD pathology is exacerbated by a Complex I deficiency, which may contribute in part to the severe reductions in ATP production previously observed in dystrophic skeletal muscle.

  17. Glucose rapidly decreases plasma membrane GLUT4 content in rat skeletal muscle.

    Science.gov (United States)

    Marette, A; Dimitrakoudis, D; Shi, Q; Rodgers, C D; Klip, A; Vranic, M

    1999-02-01

    We have previously demonstrated that chronic hyperglycemia per se decreases GLUT4 glucose transporter expression and plasma membrane content in mildly streptozotocin- (STZ) diabetic rats (Biochem. J. 284, 341-348, 1992). In the present study, we investigated the effect of an acute rise in glycemia on muscle GLUT4 and GLUT1 protein contents in the plasma membrane, in the absence of insulin elevation. Four experimental groups of rats were analyzed in the postabsorptive state: 1. Control rats. 2. Hyperglycemic STZ-diabetic rats with moderately reduced fasting insulin levels. 3. STZ-diabetic rats made normoglycemic with phlorizin treatment. 4. Phlorizin-treated (normoglycemic) STZ-diabetic rats infused with glucose for 40 min. The uniqueness of the latter model is that glycemia can be rapidly raised without any concomitant increase in plasma insulin levels. Plasma membranes were isolated from hindlimb muscle and GLUT1 and GLUT4 proteins amounts determined by Western blot analysis. As predicted, STZ-diabetes caused a significant decrease in the abundance of GLUT4 in the isolated plasma membranes. Normalization of glycemia for 3 d with phlorizin treatment restored plasma membrane GLUT4 content in muscle of STZ-diabetic rats. A sudden rise in glycemia over a period of 40 min caused the GLUT4 levels in the plasma membrane fraction to decrease to those of nontreated STZ-diabetic rats. In contrast to the GLUT4 transporter, plasma membrane GLUT1 abundance was not changed by the acute glucose challenge. It is concluded that glucose can have regulatory effect by acutely reducing plasma membrane GLUT4 protein contents in rat skeletal muscle. We hypothesize that this glucose-induced downregulation of plasma membrane GLUT4 could represent a protective mechanism against excessive glucose uptake under hyperglycemic conditions accompanied by insulin resistance.

  18. Role of PKCδ in Insulin Sensitivity and Skeletal Muscle Metabolism

    DEFF Research Database (Denmark)

    Li, Mengyao; Vienberg, Sara G; Bezy, Olivier

    2015-01-01

    Protein kinase C (PKC)δ has been shown to be increased in liver in obesity and plays an important role in the development of hepatic insulin resistance in both mice and humans. In the current study, we explored the role of PKCδ in skeletal muscle in the control of insulin sensitivity and glucose......-body insulin sensitivity and muscle insulin resistance and by 15 months of age improved the age-related decline in whole-body glucose tolerance. At 15 months of age, M-PKCδKO mice also exhibited decreased metabolic rate and lower levels of some proteins of the OXPHOS complex suggesting a role for PKCδ...... in the regulation of mitochondrial mass at older age. These data indicate an important role of PKCδ in the regulation of insulin sensitivity and mitochondrial homeostasis in skeletal muscle with aging....

  19. Combined effect of space flight and radiation on skeletal muscles of rats

    International Nuclear Information System (INIS)

    Ilyina-Kakueva, E.I.; Portugalov, V.V.

    1977-01-01

    Skeletal muscles of rats flown for 20.5 d aboard the biosatellite Cosmos-690 and irradiated with a dose of 800 rads on the 10th flight day were studied. The radiation exposure aggravated the severity of atrophic and dystrophic processes in m. soleus and atrophic process in m. gastrocnemius that developed under the conditions of weightlessness and hypokinesia. At the same time, an exposure to penetrating radiation did not affect the muscles where no flight-induced pathologies occurred. The radiation affected the pattern of reparation in those regions of the soleus muscle that developed pathology inflight, slowed down resorption of the connective tissue formed during the pathological process, and inhibited the course of the reparative process

  20. Effect of L-Carnitine on Skeletal Muscle Lipids and Oxidative Stress in Rats Fed High-Fructose Diet

    Directory of Open Access Journals (Sweden)

    Panchamoorthy Rajasekar

    2007-01-01

    Full Text Available There is evidence that high-fructose diet induces insulin resistance, alterations in lipid metabolism, and oxidative stress in rat tissues. The purpose of this study was to evaluate the effect of L-carnitine (CAR on lipid accumulation and peroxidative damage in skeletal muscle of rats fed high-fructose diet. Fructose-fed animals (60 g/100 g diet displayed decreased glucose/insulin (G/I ratio and insulin sensitivity index (ISI0,120 indicating the development of insulin resistance. Rats showed alterations in the levels of triglycerides, free fatty acids, cholesterol, and phospholipids in skeletal muscle. The condition was associated with oxidative stress as evidenced by the accumulation of lipid peroxidation products, protein carbonyls, and aldehydes along with depletion of both enzymic and nonenzymic antioxidants. Simultaneous intraperitoneal administration of CAR (300 mg/kg/day to fructose-fed rats alleviated the effects of fructose. These rats showed near-normal levels of the parameters studied. The effects of CAR in this model suggest that CAR supplementation may have some benefits in patients suffering from insulin resistance.

  1. Noninvasive Cu-64-ATSM and PET/CT Assessment of Hypoxia in Rat Skeletal Muscles and Tendons During Muscle Contractions

    DEFF Research Database (Denmark)

    Skovgaard, D.; Kjaer, M.; Madsen, J.

    2009-01-01

    the first PET/CT scan. Standardized uptake values (SUVs) were calculated for the Achilles tendons and triceps surae muscles and were correlated to gene expression of HIF1 alpha and CAIII using real-time polymerase chain reaction. Results: Immediately after the contractions, uptake of Cu-64-ATSM......The purpose of the present study was to investigate exercise-related changes in oxygenation in rat skeletal muscles and tendons noninvasively with PET/CT and the hypoxia-selective tracer Cu-64-diacetyl bis(N-4-methylthiosemicarbazone) (ATSM) and to quantitatively study concomitant changes in gene...... expression of 2 hypoxia-related genes, hypoxia-inducible factor 1 alpha (HIF1 alpha) and carbonic anhydrase III (CAIII). Methods: Two groups of Wistar rats performed 1-leg contractions of the calf muscle by electrostimulation of the sciatic nerve. After 10 min of muscle contractions, Cu-64-ATSM was injected...

  2. Noninvasive 64Cu-ATSM and PET/CT Assessment of Hypoxia in Rat Skeletal Muscles and Tendons During Muscle Contractions

    DEFF Research Database (Denmark)

    Skovgaard, Dorthe; Kjaer, Michael; Madsen, Jacob

    2009-01-01

    the first PET/CT scan. Standardized uptake values (SUVs) were calculated for the Achilles tendons and triceps surae muscles and were correlated to gene expression of HIF1alpha and CAIII using real-time polymerase chain reaction. RESULTS: Immediately after the contractions, uptake of (64)Cu......The purpose of the present study was to investigate exercise-related changes in oxygenation in rat skeletal muscles and tendons noninvasively with PET/CT and the hypoxia-selective tracer (64)Cu-diacetyl bis(N(4)-methylthiosemicarbazone) (ATSM) and to quantitatively study concomitant changes in gene...... expression of 2 hypoxia-related genes, hypoxia-inducible factor 1alpha (HIF1alpha) and carbonic anhydrase III (CAIII). METHODS: Two groups of Wistar rats performed 1-leg contractions of the calf muscle by electrostimulation of the sciatic nerve. After 10 min of muscle contractions, (64)Cu-ATSM was injected...

  3. Biomarkers of mitochondrial content in skeletal muscle of healthy young human subjects

    DEFF Research Database (Denmark)

    Larsen, Steen; Nielsen, Joachim; Hansen, Christina Neigaard

    2012-01-01

    Key points  Several biochemical measures of mitochondrial components are used as biomarkers of mitochondrial content and muscle oxidative capacity. However, no studies have validated these surrogates against a morphological measure of mitochondrial content in human subjects.  The most commonly used...... markers (citrate synthase activity, cardiolipin content, mitochondrial DNA content (mtDNA), complex I-V protein, and complex I-IV activity) were correlated with a measure of mitochondrial content (transmission electron microscopy) and muscle oxidative capacity (respiration in permeabilized fibres......).  Cardiolipin content followed by citrate synthase activity and complex I activity were the biomarkers showing the strongest association with mitochondrial content.  mtDNA was found to be a poor biomarker of mitochondrial content.  Complex IV activity was closely associated with mitochondrial oxidative...

  4. Fiber type effects on contraction-stimulated glucose uptake and GLUT4 abundance in single fibers from rat skeletal muscle.

    Science.gov (United States)

    Castorena, Carlos M; Arias, Edward B; Sharma, Naveen; Bogan, Jonathan S; Cartee, Gregory D

    2015-02-01

    To fully understand skeletal muscle at the cellular level, it is essential to evaluate single muscle fibers. Accordingly, the major goals of this study were to determine if there are fiber type-related differences in single fibers from rat skeletal muscle for: 1) contraction-stimulated glucose uptake and/or 2) the abundance of GLUT4 and other metabolically relevant proteins. Paired epitrochlearis muscles isolated from Wistar rats were either electrically stimulated to contract (E-Stim) or remained resting (No E-Stim). Single fibers isolated from muscles incubated with 2-deoxy-d-[(3)H]glucose (2-DG) were used to determine fiber type [myosin heavy chain (MHC) isoform protein expression], 2-DG uptake, and abundance of metabolically relevant proteins, including the GLUT4 glucose transporter. E-Stim, relative to No E-Stim, fibers had greater (P contraction-stimulated glucose uptake. Copyright © 2015 the American Physiological Society.

  5. Overload-induced skeletal muscle hypertrophy is not impaired in STZ-diabetic rats

    Science.gov (United States)

    Fortes, Marco Aurélio S; Pinheiro, Carlos Hermano J; Guimarães-Ferreira, Lucas; Vitzel, Kaio F; Vasconcelos, Diogo A A; Curi, Rui

    2015-01-01

    The aim of this study was to evaluate the effect of overload-induced hypertrophy on extensor digitorum longus (EDL) and soleus muscles of streptozotocin-induced diabetic rats. The overload-induced hypertrophy and absolute tetanic and twitch forces increases in EDL and soleus muscles were not different between diabetic and control rats. Phospho-Akt and rpS6 contents were increased in EDL muscle after 7 days of overload and returned to the pre-overload values after 30 days. In the soleus muscle, the contents of total and phospho-Akt and total rpS6 were increased in both groups after 7 days. The contents of total Akt in controls and total rpS6 and phospho-Akt in the diabetic rats remained increased after 30 days. mRNA expression after 7 days of overload in the EDL muscle of control and diabetic animals showed an increase in MGF and follistatin and a decrease in myostatin and Axin2. The expression of FAK was increased and of MuRF-1 and atrogin-1 decreased only in the control group, whereas Ankrd2 expression was enhanced only in diabetic rats. In the soleus muscle caused similar changes in both groups: increase in FAK and MGF and decrease in Wnt7a, MuRF-1, atrogin-1, and myostatin. Differences between groups were observed only in the increased expression of follistatin in diabetic animals and decreased Ankrd2 expression in the control group. So, insulin deficiency does not impair the overload-induced hypertrophic response in soleus and EDL muscles. However, different mechanisms seem to be involved in the comparable hypertrophic responses of skeletal muscle in control and diabetic animals. PMID:26197932

  6. Different β-adrenergic receptor density in different rat skeletal muscle fibre types

    International Nuclear Information System (INIS)

    Jensen, J.; Dahl, H.A.; Broers, O.

    1995-01-01

    The effects of adrenaline on skeletal muscle differ between fibre types. The aim of the present study was to investigate the β-adrenoceptor density, affinity and subtype in rat skeletal muscles with different fibre type composition. β-Adrenoceptors were determined in cryostat sections to avoid methodological problems with variable recovery, using the non-selective βadrenoceptor ligand [ 3 H]CGP-12177 and β 1 - and β 2 -selective cold ligands CGP 20712A and ICI 118,551. In the presence of protease inhibitors [ 3 H]CGP-12177 binding was stable, saturable, reversible, and displaceable. Scatchard analysis of binding saturation data was compatible with a single class of specific binding sites. Binding site density (B max ) was higher (P -1 ) than in adult extensor digitorum longus (4.74±0.39 fmol x mg protein -1 ), whereas the dissociation constants (K d ), 0.37±0.05 and 0.31±0.04 nM for soleus and extensor digitorum longus, respectively, were not significantly different. For young rats (5-6 weeks), B max was 11.21±0.33 and 5.45±0.11 fmol x mg protein -1 (P d was 0.27±0.02 and 0.24±0.04 nM for soleus and epitrochlearis, respectively. These results correspond to a receptor density of 2 and 1 pmol x g w.wt. -1 in muscles containing mainly type I and type II fibres, respectively. Displacement studies with CGP 20712A and ICI 118,551 were compatible with mainly β 2 -adrenoceptors, but 7-10% β 1 -adrenoceptors were present in both types of muscle. In conclusion, the receptor density is twice as high in muscles containing mainly type I muscle fibres compared to muscles containing mainly type II fibres, and this may explain some of the different effects of adrenaline between the two muscle fibre types. (au)

  7. Relationship between PPARα mRNA expression and mitochondrial respiratory function and ultrastructure of the skeletal muscle of patients with COPD.

    Science.gov (United States)

    Zhang, Jian-Qing; Long, Xiang-Yu; Xie, Yu; Zhao, Zhi-Huan; Fang, Li-Zhou; Liu, Ling; Fu, Wei-Ping; Shu, Jing-Kui; Wu, Jiang-Hai; Dai, Lu-Ming

    2017-11-02

    Peripheral muscle dysfunction is an important complication in patients with chronic obstructive pulmonary disease (COPD). The objective of this study was to explore the relationship between the levels of peroxisome proliferator-activated receptor α (PPARα) mRNA expression and the respiratory function and ultrastructure of mitochondria in the vastus lateralis of patients with COPD. Vastus lateralis biopsies were performed on 14 patients with COPD and 6 control subjects with normal lung function. PPARα mRNA levels in the muscle tissue were detected by real-time PCR. A Clark oxygen electrode was used to assess mitochondrial respiratory function. Mitochondrial number, fractional area in skeletal muscle cross-sections, and Z-line width were observed via transmission electron microscopy. The PPARα mRNA expression was significantly lower in COPD patients with low body mass index (BMIL) than in both COPD patients with normal body mass index (BMIN) and controls. Mitochondrial respiratory function (assessed by respiratory control ratio) was impaired in COPD patients, particularly in BMIL. Compared with that in the control group, mitochondrial number and fractional area were lower in the BMIL group, but were maintained in the BMIN group. Further, the Z-line became narrow in the BMIL group. PPARα mRNA expression was positively related to mitochondrial respiratory function and volume density. In COPD patients with BMIN, mitochondria volume density was maintained, while respiratory function decreased, whereas both volume density and respiratory function decreased in COPD patients with BMIL. PPARα mRNA expression levels are associated with decreased mitochondrial respiratory function and volume density, which may contribute to muscle dysfunction in COPD patients.

  8. Time course of training-induced microcirculatory changes and of vegf expression in skeletal muscles of spontaneously hypertensive female rats

    Directory of Open Access Journals (Sweden)

    S.L. Amaral

    2008-05-01

    Full Text Available Exercise-induced vessel changes modulate arterial pressure (AP in male spontaneously hypertensive rats (SHR. Vascular endothelial growth factor (VEGF is important for angiogenesis of skeletal muscle. The present study evaluated the time course of VEGF and angiogenesis after short- and long-term exercise training of female SHR and Wistar Kyoto (WKY rats, 8-9 weeks (200-250 g. Rats were allocated to daily training or remained sedentary for 3 days (N = 23 or 13 weeks (N = 23. After training, the carotid artery was catheterized for AP measurements. Locomotor (tibialis anterior and gracilis and non-locomotor skeletal muscles (temporalis were harvested and prepared for histologic and protein expression analyses. Training increased treadmill performance by all groups (SHR = 28%, WKY = 64%, 3 days and (SHR = 141%, WKY = 122%, 13 weeks. SHR had higher values of AP than WKY (174 ± 4 vs 111 ± 2 mmHg that were not altered by training. Three days of running increased VEGF expression (SHR = 28%, WKY = 36% simultaneously with an increase in capillary-to-fiber ratio in gracilis muscle (SHR = 19%, WKY = 15%. In contrast, 13 weeks of training increased gracilis capillary-to-fiber ratio (SHR = 18%, WKY = 19%, without simultaneous changes in VEGF expression. Training did not change VEGF expression and capillarity of temporalis muscle. We conclude that training stimulates time- and tissue-dependent VEGF protein expression, independent of pressure levels. VEGF triggers angiogenesis in locomotor skeletal muscle shortly after the exercise starts, but is not involved in the maintenance of capillarity after long-term exercise in female rats.

  9. Adaptation in properties of skeletal muscle to coronary artery occlusion/reperfusion in rats

    International Nuclear Information System (INIS)

    Ogoh, Shigehiko; Taguchi, Sadayoshi

    2002-01-01

    The present study was designed to determine if changes in function and metabolism of heart muscle induce alterations in characteristics of skeletal muscle. We investigated the histochemical and biochemical properties of soleus (SOL) and extensor digitorum longus (EDL) muscles in Wistar rats at the chronic phase after coronary artery occlusion/reperfusion. The size of myocardial infarct region was evaluated using a high resolution pinhole single photo emission computed tomography (SPECT) system. 4wk after left coronary artery occlusion/reperfusion, the SOL and EDL of hindlimb were dissected out and immersed in isopentane cooled with liquid nitrogen for subsequent histochemical and biochemical analysis. From SPECT imaging, the blood circulation was recovered, but the recovery of fatty acid metabolism was not observed in infarct region of heart. Citrate synthase (CS) and 3-hydroxyacyl-CoA dehydrogenase (HAD) activities in infarct region of heart were lower in the myocardial infarction (MI, n=6) group compared with that of age-matched sham-operated (Sham, n=6) group. In addition, heart muscle hypertrophy caused by the dysfunction in MI group was observed. In skeletal muscle, the atrophy and transition of fiber type distribution in MI group, reported in previous studies of heart failure, were not observed. However, the succinate dehydrogenase (SDH) activity in the slow twitch oxidative (SO) from SOL of MI group decreased by 9.8% and in the fast twitch oxidative glycolytic fibers (FOG), 8.0% as compared with sham group. Capillary density of the SO fibers from SOL of MI group also reduced by 18.5% and in the FOG fibers, 18.2% as compared with Sham group. Decreased capillary density in this study related significantly to decreased SDH activity of single muscle fibers in chronic phase of perfusion after surgical infarction. Our results make it clear that there is a difference in the reaction of skeletal muscle to coronary artery occlusion/reperfusion compared with chronic

  10. Adaptation in properties of skeletal muscle to coronary artery occlusion/reperfusion in rats

    Energy Technology Data Exchange (ETDEWEB)

    Ogoh, Shigehiko [Univ. of North Texas, Fort Worth, TX (United States). Health Science Center; Hirai, Taku [Kyoto Univ. (Japan). Graduate School of Medicine; Nohara, Ryuuji [Kitano Hospital, Osaka (Japan); Taguchi, Sadayoshi [Kyoto Univ. (Japan). Graduate School of Human and Environmental Studies

    2002-10-01

    The present study was designed to determine if changes in function and metabolism of heart muscle induce alterations in characteristics of skeletal muscle. We investigated the histochemical and biochemical properties of soleus (SOL) and extensor digitorum longus (EDL) muscles in Wistar rats at the chronic phase after coronary artery occlusion/reperfusion. The size of myocardial infarct region was evaluated using a high resolution pinhole single photo emission computed tomography (SPECT) system. 4wk after left coronary artery occlusion/reperfusion, the SOL and EDL of hindlimb were dissected out and immersed in isopentane cooled with liquid nitrogen for subsequent histochemical and biochemical analysis. From SPECT imaging, the blood circulation was recovered, but the recovery of fatty acid metabolism was not observed in infarct region of heart. Citrate synthase (CS) and 3-hydroxyacyl-CoA dehydrogenase (HAD) activities in infarct region of heart were lower in the myocardial infarction (MI, n=6) group compared with that of age-matched sham-operated (Sham, n=6) group. In addition, heart muscle hypertrophy caused by the dysfunction in MI group was observed. In skeletal muscle, the atrophy and transition of fiber type distribution in MI group, reported in previous studies of heart failure, were not observed. However, the succinate dehydrogenase (SDH) activity in the slow twitch oxidative (SO) from SOL of MI group decreased by 9.8% and in the fast twitch oxidative glycolytic fibers (FOG), 8.0% as compared with sham group. Capillary density of the SO fibers from SOL of MI group also reduced by 18.5% and in the FOG fibers, 18.2% as compared with Sham group. Decreased capillary density in this study related significantly to decreased SDH activity of single muscle fibers in chronic phase of perfusion after surgical infarction. Our results make it clear that there is a difference in the reaction of skeletal muscle to coronary artery occlusion/reperfusion compared with chronic

  11. The effects of fasting and cold exposure on metabolic rate and mitochondrial proton leak in liver and skeletal muscle of an amphibian, the cane toad Bufo marinus.

    Science.gov (United States)

    Trzcionka, M; Withers, K W; Klingenspor, M; Jastroch, M

    2008-06-01

    Futile cycling of protons across the mitochondrial inner membrane contributes significantly to standard metabolic rate in a variety of ectothermic and endothermic animals, but adaptations of the mitochondrial bioenergetics to different environmental conditions have rarely been studied in ectotherms. Changes in ambient temperature and nutritional status have a great effect on the physiological demands of ectothermic amphibians and may require the adjustment of mitochondrial efficiency. In order to investigate the effect of temperature and nutritional status on the mitochondrial level, we exposed male cane toads to either 10 degrees C or 30 degrees C and fasted half of the animals in each group. Cold exposure resulted in a fourfold reduction of the resting metabolic rate whereas nutritional status had only minor effects. The mitochondrial adjustments to each condition were observed by comparing the proton leak kinetics of isolated liver and skeletal muscle mitochondria at 25 degrees C. In response to cold exposure, liver mitochondria showed a decrease in proton conductance while skeletal muscle mitochondria were unchanged. Additional food deprivation had minor effects in skeletal muscle, but in liver we uncovered surprising differences in energy saving mechanisms between the acclimation temperatures: in warm-acclimated toads, fasting resulted in a decrease of the proton conductance whereas in cold-acclimated toads, the activity of the respiratory chain was reduced. To investigate the molecular mechanism underlying mitochondrial proton leakage, we determined the adenine-nucleotide transporter (ANT) content, which explained tissue-specific differences in the basal proton leak, but neither the ANT nor uncoupling protein (UCP) gene expression correlated with alterations of the proton leak in response to physiological stimuli.

  12. Shikonin increases glucose uptake in skeletal muscle cells and improves plasma glucose levels in diabetic Goto-Kakizaki rats.

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    Anette I Öberg

    Full Text Available BACKGROUND: There is considerable interest in identifying compounds that can improve glucose homeostasis. Skeletal muscle, due to its large mass, is the principal organ for glucose disposal in the body and we have investigated here if shikonin, a naphthoquinone derived from the Chinese plant Lithospermum erythrorhizon, increases glucose uptake in skeletal muscle cells. METHODOLOGY/PRINCIPAL FINDINGS: Shikonin increases glucose uptake in L6 skeletal muscle myotubes, but does not phosphorylate Akt, indicating that in skeletal muscle cells its effect is medaited via a pathway distinct from that used for insulin-stimulated uptake. Furthermore we find no evidence for the involvement of AMP-activated protein kinase in shikonin induced glucose uptake. Shikonin increases the intracellular levels of calcium in these cells and this increase is necessary for shikonin-mediated glucose uptake. Furthermore, we found that shikonin stimulated the translocation of GLUT4 from intracellular vesicles to the cell surface in L6 myoblasts. The beneficial effect of shikonin on glucose uptake was investigated in vivo by measuring plasma glucose levels and insulin sensitivity in spontaneously diabetic Goto-Kakizaki rats. Treatment with shikonin (10 mg/kg intraperitoneally once daily for 4 days significantly decreased plasma glucose levels. In an insulin sensitivity test (s.c. injection of 0.5 U/kg insulin, plasma glucose levels were significantly lower in the shikonin-treated rats. In conclusion, shikonin increases glucose uptake in muscle cells via an insulin-independent pathway dependent on calcium. CONCLUSIONS/SIGNIFICANCE: Shikonin increases glucose uptake in skeletal muscle cells via an insulin-independent pathway dependent on calcium. The beneficial effects of shikonin on glucose metabolism, both in vitro and in vivo, show that the compound possesses properties that make it of considerable interest for developing novel treatment of type 2 diabetes.

  13. Influence of creatine supplementation on indicators of glucose metabolism in skeletal muscle of exercised rats

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    Michel Barbosa de Araújo

    2013-12-01

    Full Text Available The purpose of this study was to evaluate the effect of creatine supplementation in the diet on indicators of glucose metabolism in skeletal muscle of exercised rats. Forty Wistar adult rats were distributed into four groups for eight weeks: 1 Control: sedentary rats that received balanced diet; 2 Creatine control: sedentary rats that received supplementation of 2% creatine in the balanced diet; 3 Trained: rats that ran on a treadmill at the Maximal Lactate Steady State and received balanced diet; and 4 Supplemented-trained: rats that ran on a treadmill at the Maximal Lactate Steady State and received creatine supplementation (2% in the balanced diet. The hydric intake increased and the body weight gain decreased in the supplemented-trained group. In the soleus muscle, the glucose oxidation increased in both supplemented groups. The production of lactate and glycemia during glucose tolerance test decreased in the supplemented-trained group. Creatine supplementation in conjunction with exercise training improved muscular glycidic metabolism of rats.

  14. Novel Tyrosine Phosphorylation Sites in Rat Skeletal Muscle Revealed by Phosphopeptide Enrichment and HPLC-ESI-MS/MS

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    Zhang, Xiangmin; Højlund, Kurt; Luo, Moulun; Meyer, Christian; Thangiah, Geetha; Yi, Zhengping

    2012-01-01

    Tyrosine phosphorylation plays a fundamental role in many cellular processes including differentiation, growth and insulin signaling. In insulin resistant muscle, aberrant tyrosine phosphorylation of several proteins has been detected. However, due to the low abundance of tyrosine phosphorylation (tyrosine phosphorylation sites have been identified in mammalian skeletal muscle to date. Here, we used immunoprecipitation of phosphotyrosine peptides prior to HPLC-ESI-MS/MS analysis to improve the discovery of tyrosine phosphorylation in relatively small skeletal muscle biopsies from rats. This resulted in the identification of 87 distinctly localized tyrosine phosphorylation sites in 46 muscle proteins. Among them, 31 appear to be novel. The tyrosine phosphorylated proteins included major enzymes in the glycolytic pathway and glycogen metabolism, sarcomeric proteins, and proteins involved in Ca2+ homeostasis and phosphocreatine resynthesis. Among proteins regulated by insulin, we found tyrosine phosphorylation sites in glycogen synthase, and two of its inhibitors, GSK-3α and DYRK1A. Moreover, tyrosine phosphorylation sites were identified in several MAP kinases and a protein tyrosine phosphatase, SHPTP2. These results provide the largest catalogue of mammalian skeletal muscle tyrosine phosphorylation sites to date and provide novel targets for the investigation of human skeletal muscle phosphoproteins in various disease states. PMID:22609512

  15. Mitochondrial Morphofunctional Alterations in Smooth Muscle Cells of Aorta in Rats

    Science.gov (United States)

    Tarán, Mariana; Llorens, Candelaria; Balceda, Ariel; Scribano, María de La Paz; Pons, Patricia; Moya, Mónica

    2014-01-01

    In an experimental model of atherogenesis induced by hyperfibrinogenemia (HF), the pharmacological response of vitamin E was studied in order to assess its antioxidant effect on the mitochondrial morphofunctional alterations in aortic smooth muscle cells. Three groups of male rats were used: (Ctr) control, (AI) atherogenesis induced for 120 days, and (AIE) atherogenesis induced for 120 days and treated with vitamin E. HF was induced by adrenalin injection (0.1 mg/day/rat) for 120 days. AIE group was treated with the administration of 3.42 mg/day/rat of vitamin E for 105 days after the first induction. Mitochondria morphology was analyzed by electronic microscopy (EM) and mitochondrial complexes (MC) by spectrophotometry. In group AI the total and mean number of mitochondria reduced significantly, the intermembranous matrix increased, and swelling was observed with respect to Ctr and AIE (P < 0.01). These damages were related to a significant decrease in the activity of citrate synthase and complexes I, II, III, and IV in group AI in comparison to Ctr (P < 0.001). Similar behavior was presented by group AI compared to AIE (P < 0.001). These results show that vitamin E produces a significative regression of inflammatory and oxidative stress process and it resolved the morphofunctional mitochondrial alterations in this experimental model of atherogenic disease. PMID:24653842

  16. PGC-1{alpha} is required for AICAR induced expression of GLUT4 and mitochondrial proteins in mouse skeletal muscle

    DEFF Research Database (Denmark)

    Leick, Lotte; Fentz, Joachim; Biensø, Rasmus S

    2010-01-01

    We tested the hypothesis that repeated activation of AMPK induces mitochondrial and glucose membrane transporter gene/protein expression via a peroxisome proliferator activated receptor Upsilon co-activator (PGC)-1alpha dependent mechanism. Whole body PGC-1alpha knockout (KO) and littermate wild...... GLUT4, cytochrome c oxidase (COX)I and cytochrome (cyt) c protein expression ~10-40% relative to saline in white muscles of the WT mice, but not of the PGC-1alpha KO mice. In line, GLUT4 and cyt c mRNA content increased 30-60% 4h after a single AICAR injection relative to saline only in WT mice. One...... and PGC-1alpha KO mice. In conclusion, we here provide genetic evidence for a major role of PGC-1alpha in AMPK mediated regulation of mitochondrial and glucose membrane transport protein expression in skeletal muscle....

  17. In utero undernutrition programs skeletal and cardiac muscle metabolism

    Directory of Open Access Journals (Sweden)

    Brittany eBeauchamp

    2016-01-01

    Full Text Available In utero undernutrition is associated with increased risk for insulin resistance, obesity, and cardiovascular disease during adult life. A common phenotype associated with low birth weight is reduced skeletal muscle mass. Given the central role of skeletal muscle in whole body metabolism, alterations in its mass as well as its metabolic characteristics may contribute to disease risk. This review highlights the metabolic alterations in cardiac and skeletal muscle associated with in utero undernutrition and low birth weight. These tissues have high metabolic demands and are known to be sites of major metabolic dysfunction in obesity, type 2 diabetes, and cardiovascular disease. Recent research demonstrates that mitochondrial energetics are decreased in skeletal and cardiac muscles of adult offspring from undernourished mothers. These effects apparently lead to the development of a thrifty phenotype, which may represent overall a compensatory mechanism programmed in utero to handle times of limited nutrient availability. However, in an environment characterized by food abundance, the effects are maladaptive and increase adulthood risks of metabolic disease.

  18. Decellularized Human Skeletal Muscle as Biologic Scaffold for Reconstructive Surgery

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    Andrea Porzionato

    2015-07-01

    Full Text Available Engineered skeletal muscle tissues have been proposed as potential solutions for volumetric muscle losses, and biologic scaffolds have been obtained by decellularization of animal skeletal muscles. The aim of the present work was to analyse the characteristics of a biologic scaffold obtained by decellularization of human skeletal muscles (also through comparison with rats and rabbits and to evaluate its integration capability in a rabbit model with an abdominal wall defect. Rat, rabbit and human muscle samples were alternatively decellularized with two protocols: n.1, involving sodium deoxycholate and DNase I; n.2, trypsin-EDTA and Triton X-NH4OH. Protocol 2 proved more effective, removing all cellular material and maintaining the three-dimensional networks of collagen and elastic fibers. Ultrastructural analyses with transmission and scanning electron microscopy confirmed the preservation of collagen, elastic fibres, glycosaminoglycans and proteoglycans. Implantation of human scaffolds in rabbits gave good results in terms of integration, although recellularization by muscle cells was not completely achieved. In conclusion, human skeletal muscles may be effectively decellularized to obtain scaffolds preserving the architecture of the extracellular matrix and showing mechanical properties suitable for implantation/integration. Further analyses will be necessary to verify the suitability of these scaffolds for in vitro recolonization by autologous cells before in vivo implantation.

  19. Mitochondrial oxidative enzyme activity in individual fibre types in hypo- and hyperthyroid rat skeletal muscles.

    Science.gov (United States)

    Johnson, M A; Turnbull, D M

    1984-04-01

    Quantitative cytochemical and biochemical techniques have been used in combination to study the response of mitochondrial oxidative enzymes in individual muscle fibre types to hypo- and hyperthyroidism. Hypothyroidism resulted in decreased activity of succinate dehydrogenase (SDH), L-glycerol-3-phosphate dehydrogenase (L-GPDH), and D-3-hydroxybutyrate dehydrogenase (D-HBDH) in all fibre types of both slow-twitch soleus and fast-twitch extensor digitorum longus (e.d.l.) muscles. In hyperthyroidism, only L-GPDH activity increased in e.d.l. but more marked increases were seen in soleus muscles, which also showed increased SDH activity. In addition to these alterations in the enzyme activity in individual fibre types the metabolic profile of the muscle is further modified by the hormone-induced interconversion of slow- to fast-twitch fibres and vice versa.

  20. Leucine stimulation of skeletal muscle protein synthesis

    International Nuclear Information System (INIS)

    Layman, D.K.; Grogan, C.K.

    1986-01-01

    Previous work in this laboratory has demonstrated a stimulatory effect of leucine on skeletal muscle protein synthesis measured in vitro during catabolic conditions. Studies in other laboratories have consistently found this effect in diaphragm muscle, however, studies examining effects on nitrogen balance or with in vivo protein synthesis in skeletal muscle are equivocal. This experiment was designed to determine the potential of leucine to stimulate skeletal muscle protein synthesis in vivo. Male Sprague-Dawley rats weighing 200 g were fasted for 12 hrs, anesthetized, a jugular cannula inserted, and protein synthesis measured using a primed continuous infusion of 14 C-tyrosine. A plateau in specific activity was reached after 30 to 60 min and maintained for 3 hrs. The leucine dose consisted of a 240 umole priming dose followed by a continuous infusion of 160 umoles/hr. Leucine infusion stimulated protein synthesis in the soleus muscle (28%) and in the red (28%) and white portions (12%) of the gastrocnemius muscle compared with controls infused with only tyrosine. The increased rates of protein synthesis were due to increased incorporation of tyrosine into protein and to decreased specific activity of the free tyrosine pool. These data indicate that infusion of leucine has the potential to stimulate in vivo protein synthesis in skeletal muscles

  1. Mitochondrial Function in an In Vitro Model of Skeletal Muscle of Patients With Protracted Critical Illness and Intensive Care Unit-Acquired Weakness.

    Science.gov (United States)

    Jiroutková, Kateřina; Krajčová, Adéla; Žiak, Jakub; Fric, Michal; Gojda, Jan; Džupa, Valér; Kalous, Martin; Tůmová, Jana; Trnka, Jan; Duška, František

    2017-09-01

    Functional mitochondria in skeletal muscle of patients with protracted critical illness and intensive care unit-acquired weakness are depleted, but remaining mitochondria have increased functional capacities of respiratory complexes II and III. This can be an adaptation to relative abundancy of fatty acid over glucose caused by insulin resistance. We hypothesized that the capacity of muscle mitochondria to oxidize fatty acid is increased in protracted critical illness. We assessed fatty acid oxidation (FAO) and mitochondrial functional indices in vitro by using extracellular flux analysis in cultured myotubes obtained by isolating and culturing satellite cells from vastus lateralis muscle biopsy samples from patients with ICU-acquired weakness (n = 6) and age-matched healthy controls (n = 7). Bioenergetic measurements were performed at baseline and after 6 days of exposure to free fatty acids (FFAs). Mitochondrial density in myotubes from ICU patients was 69% of healthy controls ( P = .051). After adjustment to mitochondrial content, there were no differences in adenosine triphosphate (ATP) synthesis or the capacity and coupling of the respiratory chain. FAO capacity in ICU patients was 157% of FAO capacity in controls ( P = .015). In myotubes of ICU patients, unlike healthy controls, the exposure to FFA significantly ( P = .009) increased maximum respiratory chain capacity. In an in vitro model of skeletal muscle of patients with protracted critical illness, we have shown signs of adaptation to increased FAO. Even in the presence of glucose and insulin, elevation of FFAs in the extracellular environment increased maximal capacity of the respiratory chain.

  2. Enhancement of Skeletal Muscle in Aged Rats Following High-Intensity Stretch-Shortening Contraction Training.

    Science.gov (United States)

    Rader, Erik P; Naimo, Marshall A; Layner, Kayla N; Triscuit, Alyssa M; Chetlin, Robert D; Ensey, James; Baker, Brent A

    2017-04-01

    Exercise is the most accessible, efficacious, and multifactorial intervention to improve health and treat chronic disease. High-intensity resistance exercise, in particular, also maximizes skeletal muscle size and strength-outcomes crucial at advanced age. However, such training is capable of inducing muscle maladaptation when misapplied at old age. Therefore, characterization of parameters (e.g., mode and frequency) that foster adaptation is an active research area. To address this issue, we utilized a rodent model that allowed training at maximal intensity in terms of muscle activation and tested the hypothesis that muscles of old rats adapt to stretch-shortening contraction (SSC) training, provided the training frequency is sufficiently low. At termination of training, normalized muscle mass (i.e., muscle mass divided by tibia length) and muscle quality (isometric force divided by normalized muscle mass) were determined. For young rats, normalized muscle mass increased by ∼20% regardless of training frequency. No difference was observed for muscle quality values after 2 days versus 3 days per week training (0.65 ± 0.09 N/mg/mm vs. 0.59 ± 0.05 N/mg/mm, respectively). For old rats following 3 days per week training, normalized muscle mass was unaltered and muscle quality was 30% lower than young levels. Following 2 days per week training at old age, normalized muscle mass increased by 17% and muscle quality was restored to young levels. To investigate this enhanced response, oxidative stress was assessed by lipid peroxidation quantification. For young rats, lipid peroxidation levels were unaltered by training. With aging, baseline levels of lipid peroxidation increased by 1.5-fold. For old rats, only 2 days per week training decreased lipid peroxidation to levels indistinguishable from young values. These results imply that, appropriately scheduled high-intensity SSC training at old age is capable of restoring muscle to a younger phenotype in terms

  3. Exercise induces transient transcriptional activation of the PGC-1a gene in human skeletal muscle

    DEFF Research Database (Denmark)

    Pilegaard, Henriette; Saltin, Bengt; Neufer, P. Darrell

    2003-01-01

    Endurance exercise training induces mitochondrial biogenesis in skeletal muscle. The peroxisome proliferator activated receptor co-activator 1a (PGC-1a) has recently been identified as a nuclear factor critical for coordinating the activation of genes required for mitochondrial biogenesis in cell...... culture and rodent skeletal muscle. To determine whether PGC-1a transcription is regulated by acute exercise and exercise training in human skeletal muscle, seven male subjects performed 4 weeks of one-legged knee extensor exercise training. At the end of training, subjects completed 3 h of two......-legged knee extensor exercise. Biopsies were obtained from the vastus lateralis muscle of both the untrained and trained legs before exercise and after 0, 2, 6 and 24 h of recovery. Time to exhaustion (2 min maximum resistance), as well as hexokinase II (HKII), citrate synthase and 3-hydroxyacyl...

  4. Diffusion tensor imaging and T2 mapping in early denervated skeletal muscle in rats.

    Science.gov (United States)

    Ha, Dong-Ho; Choi, Sunseob; Kang, Eun-Ju; Park, Hwan Tae

    2015-09-01

    To evaluate the temporal changes of diffusion tensor imaging (DTI) indices, T2 values, and visual signal intensity on various fat suppression techniques in the early state of denervated skeletal muscle in a rat model. Institutional Animal Care and Use Committee approval was obtained. Sciatic nerves of eight rats were transected for irreversible neurotmesis model. We examined normal lower leg and denervated muscles at 3 days, 1 week, and 2 weeks on a 3 Tesla MR. fractional anisotropy (FA), mean apparent diffusion coefficient (mADC), and T2 values were measured by using DTI and T2 mapping scan. We subjectively classified the signal intensity change on various fat suppression images into the following three grades: negative, suspicious, and definite change. Wilcoxon-sign rank test and Kruskal-Wallis test were used for the comparison of FA, mADC, T2 values. McNemar's test was used for comparing signal intensity change among fat suppression techniques. FA values of denervated muscles at 3 days (0.35 ± 0.06), 1 week (0.29 ± 0.04), and 2 weeks (0.34 ± 0.05) were significantly (P  0.05) change. T2 values were significantly increased at 1 week (38.11 ± 6.42 ms, P = 0.017) and markedly increased at 2 weeks (46.53 ± 5.17 ms, P = 0.012). The grade of visual signal intensity change on chemical shift selective fat saturation, STIR and IDEAL images were identical in all cases (P = 1.000). FA and T2 values can demonstrate the early temporal changes in denervated rat skeletal muscle. © 2014 Wiley Periodicals, Inc.

  5. Demonstration of a day-night rhythm in human skeletal muscle oxidative capacity.

    Science.gov (United States)

    van Moorsel, Dirk; Hansen, Jan; Havekes, Bas; Scheer, Frank A J L; Jörgensen, Johanna A; Hoeks, Joris; Schrauwen-Hinderling, Vera B; Duez, Helene; Lefebvre, Philippe; Schaper, Nicolaas C; Hesselink, Matthijs K C; Staels, Bart; Schrauwen, Patrick

    2016-08-01

    A disturbed day-night rhythm is associated with metabolic perturbations that can lead to obesity and type 2 diabetes mellitus (T2DM). In skeletal muscle, a reduced oxidative capacity is also associated with the development of T2DM. However, whether oxidative capacity in skeletal muscle displays a day-night rhythm in humans has so far not been investigated. Lean, healthy subjects were enrolled in a standardized living protocol with regular meals, physical activity and sleep to reflect our everyday lifestyle. Mitochondrial oxidative capacity was examined in skeletal muscle biopsies taken at five time points within a 24-hour period. Core-body temperature was lower during the early night, confirming a normal day-night rhythm. Skeletal muscle oxidative capacity demonstrated a robust day-night rhythm, with a significant time effect in ADP-stimulated respiration (state 3 MO, state 3 MOG and state 3 MOGS, p < 0.05). Respiration was lowest at 1 PM and highest at 11 PM (state 3 MOGS: 80.6 ± 4.0 vs. 95.8 ± 4.7 pmol/mg/s). Interestingly, the fluctuation in mitochondrial function was also observed in whole-body energy expenditure, with peak energy expenditure at 11 PM and lowest energy expenditure at 4 AM (p < 0.001). In addition, we demonstrate rhythmicity in mRNA expression of molecular clock genes in human skeletal muscle. Our results suggest that the biological clock drives robust rhythms in human skeletal muscle oxidative metabolism. It is tempting to speculate that disruption of these rhythms contribute to the deterioration of metabolic health associated with circadian misalignment.

  6. Thyroid hormone uptake and T4 derived T3 formation in different skeletal muscle types of normal and hyperthyroid rats

    International Nuclear Information System (INIS)

    Hardeveld, C. van; Kassenaar, A.A.H.

    1978-01-01

    In this study hind-limb perfusion was used to investigate conversion of T 4 to T 3 in skeletal muscle tissue. For this purpose the rats were depleted of thyroid hormones by thyroid ablation with 0.75 mCi 131 I and were perfused 2 weeks later, when the skeletal muscle tissue consumed oxygen at a normal rate due to one subcutaneous dose of 10 μg T 3 /100 g b. w. 3 days before the perfusion experiments were started. T 4 * of high specific activity (> 2000 μCi/μg) was added to the perfusate. In the muscle (mixed type) a mean T 4 → T 3 conversion of 2% (range 0.5-3.9) was found after 120 min of perfusion. T 3 generation from T 4 in skeletal muscle did not correspond with T 3 muscle uptake. This observation makes a significant overestimation of T 3 by selective uptake of a small contamination of T 3 * in the T 4 * preparation highly improbable. In red muscle the T 4 and T 3 uptake was about 50 % higher than in white muscle. The observed Tetracsup(c) and T 3 sup(c) were significantly higher in red than in white muscle. The uptake of thyroid hormones by both muscle types was not changed in hyperthyroid rats. The Tetrac and T 3 formation from T 4 , however, was increased in red muscles of hyperthyroid rats. The results show that thyroid hormone metabolism can vary markedly depending upon the type of muscle studied and they present a basis for a better understanding of clinical and biochemical evidence for a different susceptibility of red and white muscle fibers to thyroid hormones. (Abbreviations: *= 125 I; **= 131 I; T 3 sup(c)=T 4 derived T 3 ; Tetracsup(c)=T 4 derived Tetrac) (author)

  7. Extrarenal potassium adaptation: role of skeletal muscle

    International Nuclear Information System (INIS)

    Blachley, J.D.; Crider, B.P.; Johnson, J.H.

    1986-01-01

    Following the ingestion of a high-potassium-content diet for only a few days, the plasma potassium of rats rises only modestly in response to a previously lethal dose of potassium salts. This acquired tolerance, termed potassium adaptation, is principally the result of increased capacity to excrete potassium into the urine. However, a substantial portion of the acute potassium dose is not immediately excreted and is apparently translocated into cells. Previous studies have failed to show an increase in the content of potassium of a variety of tissues from such animals. Using 86 Rb as a potassium analogue, we have shown that the skeletal muscle of potassium-adapted rats takes up significantly greater amounts of potassium in vivo in response to an acute challenge than does that of control animals. Furthermore, the same animals exhibit greater efflux of 86 Rb following the termination of the acute infusion. We have also shown that the Na+-K+-ATPase activity and ouabain-binding capacity of skeletal muscle microsomes are increased by the process of potassium adaptation. We conclude that skeletal muscle is an important participant in potassium adaptation and acts to temporarily buffer acute increases in the extracellular concentration of potassium

  8. Proteomic analysis indicates that mitochondrial energy metabolism in skeletal muscle tissue is negatively correlated with feed efficiency in pigs

    Science.gov (United States)

    Fu, Liangliang; Xu, Yueyuan; Hou, Ye; Qi, Xiaolong; Zhou, Lian; Liu, Huiying; Luan, Yu; Jing, Lu; Miao, Yuanxin; Zhao, Shuhong; Liu, Huazhen; Li, Xinyun

    2017-03-01

    Feed efficiency (FE) is a highly important economic trait in pig production. Investigating the molecular mechanisms of FE is essential for trait improvement. In this study, the skeletal muscle proteome of high-FE and low-FE pigs were investigated by the iTRAQ approach. A total of 1780 proteins were identified, among which 124 proteins were differentially expressed between the high- and low-FE pigs, with 74 up-regulated and 50 down-regulated in the high-FE pigs. Ten randomly selected differentially expressed proteins (DEPs) were validated by Western blotting and quantitative PCR (qPCR). Gene ontology (GO) analysis showed that all the 25 DEPs located in mitochondria were down-regulated in the high-FE pigs. Furthermore, the glucose-pyruvate-tricarboxylic acid (TCA)-oxidative phosphorylation energy metabolism signaling pathway was found to differ between high- and low-FE pigs. The key enzymes involved in the conversion of glucose to pyruvate were up-regulated in the high-FE pigs. Thus, our results suggested mitochondrial energy metabolism in the skeletal muscle tissue was negatively correlated with FE in pigs, and glucose utilization to generate ATP was more efficient in the skeletal muscle tissue of high-FE pigs. This study offered new targets and pathways for improvement of FE in pigs.

  9. The lumbrical muscle: a novel in situ system to evaluate adult skeletal muscle proteolysis and anticatabolic drugs for therapeutic purposes.

    Science.gov (United States)

    Bergantin, Leandro Bueno; Figueiredo, Leonardo Bruno; Godinho, Rosely Oliveira

    2011-12-01

    The molecular regulation of skeletal muscle proteolysis and the pharmacological screening of anticatabolic drugs have been addressed by measuring tyrosine release from prepubertal rat skeletal muscles, which are thin enough to allow adequate in vitro diffusion of oxygen and substrates. However, the use of muscle at accelerated prepubertal growth has limited the analysis of adult muscle proteolysis or that associated with aging and neurodegenerative diseases. Here we established the adult rat lumbrical muscle (4/hindpaw; 8/rat) as a new in situ experimental model for dynamic measurement of skeletal muscle proteolysis. By incubating lumbrical muscles attached to their individual metatarsal bones in Tyrode solution, we showed that the muscle proteolysis rate of adult and aged rats (3-4 to 24 mo old) is 45-25% of that in prepubertal animals (1 mo old), which makes questionable the usual extrapolation of proteolysis from prepubertal to adult/senile muscles. While acute mechanical injury or 1- to 7-day denervation increased tyrosine release from adult lumbrical muscle by up to 60%, it was reduced by 20-28% after 2-h incubation with β-adrenoceptor agonists, forskolin or phosphodiesterase inhibitor IBMX. Using inhibitors of 26S-proteasome (MG132), lysosome (methylamine), or calpain (E64/leupeptin) systems, we showed that ubiquitin-proteasome is accountable for 40-50% of total lumbrical proteolysis of adult, middle-aged, and aged rats. In conclusion, the lumbrical model allows the analysis of muscle proteolysis rate from prepubertal to senile rats. By permitting eight simultaneous matched measurements per rat, the new model improves similar protocols performed in paired extensor digitorum longus (EDL) muscles from prepubertal rats, optimizing the pharmacological screening of drugs for anticatabolic purposes.

  10. Dietary fish oil delays hypoxic skeletal muscle fatigue and enhances caffeine-stimulated contractile recovery in the rat in vivo hindlimb.

    Science.gov (United States)

    Peoples, Gregory E; McLennan, Peter L

    2017-06-01

    Oxygen efficiency influences skeletal muscle contractile function during physiological hypoxia. Dietary fish oil, providing docosahexaenoic acid (DHA), reduces the oxygen cost of muscle contraction. This study used an autologous perfused rat hindlimb model to examine the effects of a fish oil diet on skeletal muscle fatigue during an acute hypoxic challenge. Male Wistar rats were fed a diet rich in saturated fat (SF), long-chain (LC) n-6 polyunsaturated fatty acids (n-6 PUFA), or LC n-3 PUFA DHA from fish oil (FO) (8 weeks). During anaesthetised and ventilated conditions (normoxia 21% O 2 (SaO 2 -98%) and hypoxia 14% O 2 (SaO 2 -89%)) the hindlimb was perfused at a constant flow and the gastrocnemius-plantaris-soleus muscle bundle was stimulated via sciatic nerve (2 Hz, 6-12V, 0.05 ms) to established fatigue. Caffeine (2.5, 5, 10 mM) was supplied to the contracting muscle bundle via the arterial cannula to assess force recovery. Hypoxia, independent of diet, attenuated maximal twitch tension (normoxia: 82 ± 8; hypoxia: 41 ± 2 g·g -1 tissue w.w.). However, rats fed FO sustained higher peak twitch tension compared with the SF and n-6 PUFA groups (P recovery was enhanced in the FO-fed animals (SF: 41 ± 3; n-6 PUFA: 40 ± 4; FO: 52 ± 7% recovery; P < 0.05). These results support a physiological role of DHA in skeletal muscle membranes when exposed to low-oxygen stress that is consistent with the attenuation of muscle fatigue under physiologically normoxic conditions.

  11. Mild cold induced thermogenesis: are BAT and skeletal muscle synergistic partners?

    Science.gov (United States)

    Bal, Naresh C; Maurya, Santosh K; Pani, Sunil; Sethy, Chinmayee; Banerjee, Ananya; Das, Sarita; Patnaik, Srinivas; Kundu, Chanakya N

    2017-10-31

    There are two well-described thermogenic sites; brown adipose tissue (BAT) and skeletal muscle, which utilize distinct mechanisms of heat production. In BAT, mitochondrial metabolism is the molecular basis of heat generation, while it serves only a secondary role in supplying energy for thermogenesis in muscle. Here, we wanted to document changes in mitochondrial ultrastructure in these two tissue types based upon adaptation to mild (16°C) and severe (4°C) cold in mice. When reared at thermoneutrality (29°C), mitochondria in both tissues were loosely packed with irregular cristae. Interestingly, adaptation to even mild cold initiated ultrastructural remodeling of mitochondria including acquisition of more elaborate cristae structure in both thermogenic sites. The shape of mitochondria in the BAT remained mostly circular, whereas the intermyofibrilar mitochondria in the skeletal muscle became more elongated and tubular. The most dramatic remodeling of mitochondrial architecture was observed upon adaptation to severe cold. In addition, we report cold-induced alteration in levels of humoral factors: fibroblast growth factor 21 (FGF21), IL1α, peptide YY (PYY), tumor necrosis factor α (TNFα), and interleukin 6 (IL6) were all induced whereas both insulin and leptin were down-regulated. In summary, adaptation to cold leads to enhanced cristae formation in mitochondria in skeletal muscle as well as the BAT. Further, the present study indicates that circulating cytokines might play an important role in the synergistic recruitment of the thermogenic program including cross-talk between muscle and BAT. © 2017 The Author(s).

  12. Effect of endurance training on glucose transport capacity and glucose transporter expression in rat skeletal muscle

    DEFF Research Database (Denmark)

    Ploug, T; Stallknecht, B M; Pedersen, O

    1990-01-01

    exhaustive single exercise session the day before experiment both maximum insulin- and contraction-stimulated transport rates were increased in all muscle types in trained rats. Accordingly, the increased glucose transport capacity in trained muscle was not due to a residual effect of the last training...... session. Half-times for reversal of contraction-induced glucose transport were similar in trained and untrained muscles. The concentrations of mRNA for GLUT-1 (the erythrocyte-brain-Hep G2 glucose transporter) and GLUT-4 (the adipocyte-muscle glucose transporter) were increased approximately twofold......The effect of 10 wk endurance swim training on 3-O-methylglucose (3-MG) uptake (at 40 mM 3-MG) in skeletal muscle was studied in the perfused rat hindquarter. Training resulted in an increase of approximately 33% for maximum insulin-stimulated 3-MG transport in fast-twitch red fibers...

  13. Regulation of skeletal muscle mitochondrial activity by thyroid hormones: focus on "old" triiodothyronine and the "emerging" 3,5-diiodothyronine".

    OpenAIRE

    Assunta eLombardi; Maria eMoreno; Pieter eDe Lange; Susanna eIossa; Rosa Anna eBusiello; Fernando eGoglia

    2015-01-01

    3,5,3'-triiodo-L-thyronine (T3) plays a crucial role in regulating metabolic rate and fuel oxidation; however, the mechanisms by which it affects whole-body energy metabolism are still not completely understood. Skeletal muscle (SKM) plays a relevant role in energy metabolism and responds to thyroid state by remodeling the metabolic characteristics and cytoarchitecture of myocytes. These processes are coordinated with changes in mitochondrial content, bioenergetics, substrate oxidation rate, ...

  14. AMP deaminase histochemical activity and immunofluorescent isozyme localization in rat skeletal muscle

    Science.gov (United States)

    Thompson, J. L.; Sabina, R. L.; Ogasawara, N.; Riley, D. A.

    1992-01-01

    The cellular distribution of AMP deaminase (AMPda) isozymes was documented for rat soleus and plantaris muscles, utilizing immunofluorescence microscopy and immunoprecipitation methods. AMPda is a ubiquitous enzyme existing as three distinct isozymes, A, B and C, which were initially purified from skeletal muscle, liver (and kidney), and heart, respectively. AMPda-A is primarily concentrated subsarcolemmally and intermyofibrillarly within muscle cells, while isozymes B and C are concentrated within non-myofiber elements of muscle tissue. AMPda-B is principally associated with connective tissues surrounding neural elements and the muscle spindle capsule, and AMPda-C is predominantly associated with circulatory elements, such as arterial and venous walls, capillary endothelium, and red blood cells. These specific localizations, combined with documented differences in kinetic properties, suggest multiple functional roles for the AMPda isozymes or temporal segregation of similar AMPda functions. Linkage of the AMPda substrate with adenosine production pathways at the AMP level and the localization of isozyme-C in vascular tissue suggest a regulatory role in the microcirculation.

  15. Injectable skeletal muscle matrix hydrogel promotes neovascularization and muscle cell infiltration in a hindlimb ischemia model

    Directory of Open Access Journals (Sweden)

    JA DeQuach

    2012-06-01

    Full Text Available Peripheral artery disease (PAD currently affects approximately 27 million patients in Europe and North America, and if untreated, may progress to the stage of critical limb ischemia (CLI, which has implications for amputation and potential mortality. Unfortunately, few therapies exist for treating the ischemic skeletal muscle in these conditions. Biomaterials have been used to increase cell transplant survival as well as deliver growth factors to treat limb ischemia; however, existing materials do not mimic the native skeletal muscle microenvironment they are intended to treat. Furthermore, no therapies involving biomaterials alone have been examined. The goal of this study was to develop a clinically relevant injectable hydrogel derived from decellularized skeletal muscle extracellular matrix and examine its potential for treating PAD as a stand-alone therapy by studying the material in a rat hindlimb ischemia model. We tested the mitogenic activity of the scaffold’s degradation products using an in vitro assay and measured increased proliferation rates of smooth muscle cells and skeletal myoblasts compared to collagen. In a rat hindlimb ischemia model, the femoral artery was ligated and resected, followed by injection of 150 µL of skeletal muscle matrix or collagen 1 week post-injury. We demonstrate that the skeletal muscle matrix increased arteriole and capillary density, as well as recruited more desmin-positive and MyoD-positive cells compared to collagen. Our results indicate that this tissue-specific injectable hydrogel may be a potential therapy for treating ischemia related to PAD, as well as have potential beneficial effects on restoring muscle mass that is typically lost in CLI.

  16. Imaging mass spectrometry reveals fiber-specific distribution of acetylcarnitine and contraction-induced carnitine dynamics in rat skeletal muscles.

    Science.gov (United States)

    Furuichi, Yasuro; Goto-Inoue, Naoko; Manabe, Yasuko; Setou, Mitsutoshi; Masuda, Kazumi; Fujii, Nobuharu L

    2014-10-01

    Carnitine is well recognized as a key regulator of long-chain fatty acyl group translocation into the mitochondria. In addition, carnitine, as acetylcarnitine, acts as an acceptor of excess acetyl-CoA, a potent inhibitor of pyruvate dehydrogenase. Here, we provide a new methodology for accurate quantification of acetylcarnitine content and determination of its localization in skeletal muscles. We used matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) to visualize acetylcarnitine distribution in rat skeletal muscles. MALDI-IMS and immunohistochemistry of serial cross-sections showed that acetylcarnitine was enriched in the slow-type muscle fibers. The concentration of ATP was lower in muscle regions with abundant acetylcarnitine, suggesting a relationship between acetylcarnitine and metabolic activity. Using our novel method, we detected an increase in acetylcarnitine content after muscle contraction. Importantly, this increase was not detected using traditional biochemical assays of homogenized muscles. We also demonstrated that acetylation of carnitine during muscle contraction was concomitant with glycogen depletion. Our methodology would be useful for the quantification of acetylcarnitine and its contraction-induced kinetics in skeletal muscles. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. L-carnitine pretreatment protects slow-twitch skeletal muscles in a rat model of ischemia-reperfusion injury.

    Science.gov (United States)

    Demirel, Mert; Kaya, Burak; Cerkez, Cem; Ertunc, Mert; Sara, Yildirim

    2013-10-01

    Ischemia-reperfusion (I/R) injury negatively affects the outcome of surgical interventions for amputated or severely traumatized extremities. This study aimed to evaluate the protective role of l-carnitine on the contractile properties of fast-twitch (extensor digitorum longus [EDL]) and slow-twitch (soleus [SOL]) skeletal muscles following I/R-induced injury in a rat model. Rats were divided into 4 groups (1) saline pretreatment, (2) l-carnitine pretreatment, (3) saline pretreatment and I/R, and (4) l-carnitine pretreatment and I/R. Twitch and tetanic contractions in the EDL and SOL muscles in each group were recorded. Additionally, a fatigue protocol was performed in these muscles. Twitch and tetanic contraction amplitudes were lower in the EDL and SOL muscles in which I/R was induced (P contraction amplitude in the SOL muscles following I/R (P muscles. l-Carnitine pretreatment did not alter the fatigue response in any of the muscles.

  18. Evaluation of microRNAs − 208 and 133a/b as differential biomarkers of acute cardiac and skeletal muscle toxicity in rats

    Energy Technology Data Exchange (ETDEWEB)

    Calvano, Jacqueline, E-mail: Jacqueline.Calvano@bms.com [Drug Safety Evaluation, Bristol-Myers Squibb, 1 Squibb Drive, New Brunswick, NJ 08903 (United States); Achanzar, William; Murphy, Bethanne [Drug Safety Evaluation, Bristol-Myers Squibb, 1 Squibb Drive, New Brunswick, NJ 08903 (United States); DiPiero, Janet [Discovery Toxicology, Bristol-Myers Squibb, Route 206 and Province Line Road, Lawrenceville, NJ 08540 (United States); Hixson, Clifford; Parrula, Cecilia; Burr, Holly; Mangipudy, Raja; Tirmenstein, Mark [Drug Safety Evaluation, Bristol-Myers Squibb, 1 Squibb Drive, New Brunswick, NJ 08903 (United States)

    2016-12-01

    Conventional circulating biomarkers of cardiac and skeletal muscle (SKM) toxicity lack specificity and/or have a short half-life. MicroRNAs (miRNAs) are currently being assessed as biomarkers of tissue injury based on their long half-life in blood and selective expression in certain tissues. To assess the utility of miRNAs as biomarkers of cardiac and SKM injury, male Sprague–Dawley rats received a single dose of isoproterenol (ISO); metaproterenol (MET); allylamine (AAM); mitoxantrone (MIT); acetaminophen (APAP) or vehicle. Blood and tissues were collected from rats in each group at 4, 24 and 48 h. ISO, MET, and AAM induced cardiac and SKM lesions and APAP induced liver specific lesions. There was no evidence of tissue injury with MIT by histopathology. Serum levels of candidate miRNAs were compared to conventional serum biomarkers of SKM/cardiac toxicity. Increases in heart specific miR-208 only occurred in rats with cardiac lesions alone and were increased for a longer duration than cardiac troponin and FABP3 (cardiac biomarkers). ISO, MET and AAM induced increases in MyL3 and skeletal muscle troponin (sTnl) (SKM biomarkers). MIT induced large increases in sTnl indicative of SKM toxicity, but sTnl levels were also increased in APAP-treated rats that lacked SKM toxicity. Serum levels of miR-133a/b (enriched in cardiac and SKM) increased following ISO, MET, AAM and MIT treatments but were absent in APAP-treated rats. Our results suggest that miR-133a/b are sensitive and specific markers of SKM and cardiac toxicity and that miR-208 used in combination with miR-133a/b can be used to differentiate cardiac from SKM toxicity. - Highlights: • MiR-208 is specifically expressed in rat hearts. • MiR-133a/b are enriched in rat cardiac/skeletal muscle. • MiR-133a/b are sensitive and specific markers of muscle/cardiac toxicity. • MiR-208 can be used to differentiate cardiac toxicity from skeletal muscle toxicity.

  19. Effect of ascorbic acid on fatigue of skeletal muscle fibres in long term cold exposed sprague dawley rats

    International Nuclear Information System (INIS)

    Rashid, A.; Ayub, M.

    2011-01-01

    On exposure to prolonged cold temperature, the body responds for effective heat production both by shivering and non-shivering thermo genesis. Cold exposure increases the production of reactive oxygen species which influence the sarcoplasmic reticulum Ca/sup ++/ release from the skeletal muscles and affect their contractile properties. The role of ascorbic acid supplementation on force of contraction during fatigue of cold exposed skeletal muscles was evaluated in this study. Method: Ninety healthy, male Sprague Dawley rats were randomly divided into three groups of control, cold exposed, and cold exposed with ascorbic acid 500 mg/L supplementation mixed in drinking water. Group II and III were given cold exposure by keeping their cages in ice-filled tubs for 1 hr/day for one month. After one month, the extensor digitorum longus muscle was dissected out and force of contraction during fatigue in the skeletal muscle fibres was analysed on a computerised data acquisition system. Results: The cold exposed group showed a significant delay in the force of contraction during fatigue of skeletal muscle fibres compared to control group. Group III showed easy fatigability and a better force of contraction than the cold exposed group. Conclusions: Ascorbic acid increases the force of contraction and decreases resistance to fatigue in the muscles exposed to chronic cold. (author)

  20. Increased cellular proliferation in rat skeletal muscle and tendon in response to exercise

    DEFF Research Database (Denmark)

    Skovgaard, Dorthe; Bayer, Monika L; Mackey, Abigail

    2010-01-01

    PURPOSE: The purpose of this study is to investigate exercise-induced cellular proliferation in rat skeletal muscle/tendon with the use of 3'-[F-18]fluoro-3'deoxythymidine (FLT) and to quantitatively study concomitant changes in the proliferation-associated factor, Ki67. PROCEDURES: Wistar rats (...... = 13) performed 3 days of treadmill running. Cellular proliferation was investigated 3 days before and 48 h after the running exercise with the use of FLT and positron emission tomography/computed tomography (PET/CT). Results were compared to a sedentary control group (n = 10). Image......-derived results were supported by a correlation in calf muscle to Ki67 (protein and mRNA level), while this coherence was not found in tendon. CONCLUSION: FLT-PET seems to be a promising tool for imaging of exercise-induced cellular proliferation in musculo-tendinous tissue....

  1. Effect of hypothermia on the insulin-receptor interaction in skeletal muscle plasma membranes

    International Nuclear Information System (INIS)

    Torlinska T, Mackowiak P.; Nogowski L, Kozlik J.

    1996-01-01

    The aim of the study was to investigate the effect of hypothermia on (125-I)-insulin binding to rat skeletal muscle membranes and to determine whether the decrease in blood insulin concentration could be related to changes in the number or in the affinity of insulin receptor sites according to the down-regulation theory. Rat skeletal muscle membranes were prepared from control, normothermic rats (Tr = 35.6 ± 0.3 degree C) and hypothermic rats (Tr = 26.0 ± 0.5 deg C) and purified according to Havrankowa. In order to determine the kinetic parameters of the hormone-receptor interaction the data from the competition binding studies were analysed by the method of Scatchard using the LIGAND Pc.v.3.1. computer program of Munson and Rodbard. We have shown that under hypothermic conditions insulin receptors number is significantly increased in specific hindlimb skeletal muscles but the changes take place mainly in the low affinity receptors class. The phenomenon probably results from the lack of spare high affinity insulin receptors in skeletal muscle as shown recently by Camps et al. (author). 36 refs., 3 figs, 2 tabs

  2. Effects of Heat Stress Treatment on Age-dependent Unfolded Protein Response in Different Types of Skeletal Muscle.

    Science.gov (United States)

    Tamura, Yuki; Matsunaga, Yutaka; Kitaoka, Yu; Hatta, Hideo

    2017-03-01

    Mitochondrial and endoplasmic reticulum (ER) stress, and subsequently activated responses (mitochondrial/ER unfolded protein responses; UPRmt/UPRER), are involved in the pathogenesis of sarcopenia. To extend both basic and translational knowledge, we examined (i) whether age-induced mitochondrial and ER stress depend on skeletal muscle type in mice and (ii) whether heat stress treatment, a suggested strategy for sarcopenia, improves age-induced mitochondrial and ER stress. Aged (21-month-old) mice showed more severe mitochondrial stress and UPRmt than young (12-week-old) mice, based on increased oxidative stress, mitochondrial proteases, and mitochondrial E3 ubiquitin ligase. The aged mice also showed ER stress and UPRER, based on decreased ER enzymes and increased ER stress-related cell death. These changes were much more evident in soleus muscle than in gastrocnemius and plantaris muscles. After daily heat stress treatment (40 °C chamber for 30 minutes per day) for 4 weeks, mice showed remarkable improvements in age-related changes in soleus muscle. Heat stress had only minor effects in gastrocnemius and plantaris muscles. Based on these findings, age-associated mitochondrial stress, ER stress, and UPRmt/ER vary qualitatively with skeletal muscle type. Our results suggest a molecular basis for the beneficial effects of heat stress on muscle atrophy with age in soleus muscle. © The Author 2016. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. Voluntary resistance running wheel activity pattern and skeletal muscle growth in rats.

    Science.gov (United States)

    Legerlotz, Kirsten; Elliott, Bradley; Guillemin, Bernard; Smith, Heather K

    2008-06-01

    The aims of this study were to characterize the pattern of voluntary activity of young rats in response to resistance loading on running wheels and to determine the effects of the activity on the growth of six limb skeletal muscles. Male Sprague-Dawley rats (4 weeks old) were housed individually with a resistance running wheel (R-RUN, n = 7) or a conventional free-spinning running wheel (F-RUN, n = 6) or without a wheel, as non-running control animals (CON, n = 6). The torque required to move the wheel in the R-RUN group was progressively increased, and the activity (velocity, distance and duration of each bout) of the two running wheel groups was recorded continuously for 45 days. The R-RUN group performed many more, shorter and faster bouts of running than the F-RUN group, yet the mean daily distance was not different between the F-RUN (1.3 +/- 0.2 km) and R-RUN group (1.4 +/- 0.6 km). Only the R-RUN resulted in a significantly (P RUN and R-RUN led to a significantly greater wet mass relative to increase in body mass and muscle fibre cross-sectional area in the soleus muscle compared with CON. We conclude that the pattern of voluntary activity on a resistance running wheel differs from that on a free-spinning running wheel and provides a suitable model to induce physiological muscle hypertrophy in rats.

  4. Early Stress History Alters Serum Insulin-Like Growth Factor-1 and Impairs Muscle Mitochondrial Function in Adult Male Rats.

    Science.gov (United States)

    Ghosh, S; Banerjee, K K; Vaidya, V A; Kolthur-Seetharam, U

    2016-09-01

    Early-life adversity is associated with an enhanced risk for adult psychopathology. Psychiatric disorders such as depression exhibit comorbidity for metabolic dysfunction, including obesity and diabetes. However, it is poorly understood whether, besides altering anxiety and depression-like behaviour, early stress also evokes dysregulation of metabolic pathways and enhances vulnerability for metabolic disorders. We used the rodent model of the early stress of maternal separation (ES) to examine the effects of early stress on serum metabolites, insulin-like growth factor (IGF)-1 signalling, and muscle mitochondrial content. Adult ES animals exhibited dyslipidaemia, decreased serum IGF1 levels, increased expression of liver IGF binding proteins, and a decline in the expression of specific metabolic genes in the liver and muscle, including Pck1, Lpl, Pdk4 and Hmox1. These changes occurred in the absence of alterations in body weight, food intake, glucose tolerance, insulin tolerance or insulin levels. ES animals also exhibited a decline in markers of muscle mitochondrial content, such as mitochondrial DNA levels and expression of TFAM (transcription factor A, mitochondrial). Furthermore, the expression of several genes involved in mitochondrial function, such as Ppargc1a, Nrf1, Tfam, Cat, Sesn3 and Ucp3, was reduced in skeletal muscle. Adult-onset chronic unpredictable stress resulted in overlapping and distinct consequences from ES, including increased circulating triglyceride levels, and a decline in the expression of specific metabolic genes in the liver and muscle, with no change in the expression of genes involved in muscle mitochondrial function. Taken together, our results indicate that a history of early adversity can evoke persistent changes in circulating IGF-1 and muscle mitochondrial function and content, which could serve to enhance predisposition for metabolic dysfunction in adulthood. © 2016 British Society for Neuroendocrinology.

  5. The effect of transcutaneous application of carbon dioxide (CO2) on skeletal muscle

    International Nuclear Information System (INIS)

    Oe, Keisuke; Ueha, Takeshi; Sakai, Yoshitada; Niikura, Takahiro; Lee, Sang Yang; Koh, Akihiro; Hasegawa, Takumi; Tanaka, Masaya; Miwa, Masahiko; Kurosaka, Masahiro

    2011-01-01

    Highlights: → PGC-1α is up-regulated as a result of exercise such as mitochondrial biogenesis and muscle fiber-type switching, and up-regulation of VEGF. → We demonstrated transcutaneous application of CO 2 up-regulated the gene expression of PGC-1α, SIRT1 and VEGF, and instance of muscle fiber switching. → Transcutaneous application of CO 2 may cause similar effect to aerobic exercise in skeletal muscle. -- Abstract: In Europe, carbon dioxide therapy has been used for cardiac disease and skin problems for a long time. However there have been few reports investigating the effects of carbon dioxide therapy on skeletal muscle. Peroxisome proliferators-activated receptor (PPAR)-gamma coactivator-1 (PGC-1α) is up-regulated as a result of exercise and mediates known responses to exercise, such as mitochondrial biogenesis and muscle fiber-type switching, and neovascularization via up-regulation of vascular endothelial growth factor (VEGF). It is also known that silent mating type information regulation 2 homologs 1 (SIRT1) enhances PGC-1α-mediated muscle fiber-type switching. Previously, we demonstrated transcutaneous application of CO 2 increased blood flow and a partial increase of O 2 pressure in the local tissue known as the Bohr effect. In this study, we transcutaneously applied CO 2 to the lower limbs of rats, and investigated the effect on the fast muscle, tibialis anterior (TA) muscle. The transcutaneous CO 2 application caused: (1) the gene expression of PGC-1α, silent mating type information regulation 2 homologs 1 (SIRT1) and VEGF, and increased the number of mitochondria, as proven by real-time PCR and immunohistochemistry, (2) muscle fiber switching in the TA muscle, as proven by isolation of myosin heavy chain and ATPase staining. Our results suggest the transcutaneous application of CO 2 may have therapeutic potential for muscular strength recovery resulting from disuse atrophy in post-operative patients and the elderly population.

  6. Vanilloid receptor expressed in the sarcoplasmic reticulum of rat skeletal muscle

    International Nuclear Information System (INIS)

    Xin Hong; Tanaka, Hideyuki; Yamaguchi, Maki; Takemori, Shigeru; Nakamura, Akio; Kohama, Kazuhiro

    2005-01-01

    Vanilloid receptor subtype 1 (VR1) was cloned as a capsaicin receptor from neuronal cells of dorsal root ganglia. VR1 was subsequently found in a few non-neuronal tissues, including skeletal muscle [Onozawa et al., Tissue distribution of capsaicin receptor in the various organs of rats, Proc. Jpn. Acad. Ser. B 76 (2000) 68-72]. We confirmed the expression of VR1 in muscle cells using the RT-PCR method and Western blot analysis. Immunostaining studies with a confocal microscope and an electron microscope indicated that VR1 was present in the sarcoplasmic reticulum (SR), a store of Ca 2+ . The SR releases Ca 2+ to cause a contraction when a muscle is excited. However, SR still releases a small amount of Ca 2+ under relaxed conditions. We found that this leakage was enhanced by capsaicin and was antagonized by capsazepine, a capsaicin blocker, indicating that leakage of Ca 2+ occurs through a channel composed of VR1

  7. Ca2+-Dependent Regulations and Signaling in Skeletal Muscle: From Electro-Mechanical Coupling to Adaptation

    Science.gov (United States)

    Gehlert, Sebastian; Bloch, Wilhelm; Suhr, Frank

    2015-01-01

    Calcium (Ca2+) plays a pivotal role in almost all cellular processes and ensures the functionality of an organism. In skeletal muscle fibers, Ca2+ is critically involved in the innervation of skeletal muscle fibers that results in the exertion of an action potential along the muscle fiber membrane, the prerequisite for skeletal muscle contraction. Furthermore and among others, Ca2+ regulates also intracellular processes, such as myosin-actin cross bridging, protein synthesis, protein degradation and fiber type shifting by the control of Ca2+-sensitive proteases and transcription factors, as well as mitochondrial adaptations, plasticity and respiration. These data highlight the overwhelming significance of Ca2+ ions for the integrity of skeletal muscle tissue. In this review, we address the major functions of Ca2+ ions in adult muscle but also highlight recent findings of critical Ca2+-dependent mechanisms essential for skeletal muscle-regulation and maintenance. PMID:25569087

  8. Training-induced adaptation of oxidative phosphorylation in skeletal muscles.

    OpenAIRE

    Korzeniewski, Bernard; Zoladz, Jerzy A

    2003-01-01

    Muscle training/conditioning improves the adaptation of oxidative phosphorylation in skeletal muscles to physical exercise. However, the mechanisms underlying this adaptation are still not understood fully. By quantitative analysis of the existing experimental results, we show that training-induced acceleration of oxygen-uptake kinetics at the onset of exercise and improvement of ATP/ADP stability due to physical training are mainly caused by an increase in the amount of mitochondrial protein...

  9. Mitochondrial energetic metabolism perturbations in skeletal muscles and brain of zebrafish (Danio rerio) exposed to low concentrations of waterborne uranium

    Energy Technology Data Exchange (ETDEWEB)

    Lerebours, Adelaide; Adam-Guillermin, Christelle [Laboratoire de Radioecologie et d' Ecotoxicologie, Institut de Radioprotection et de Surete Nucleaire, Bat 186, BP 3, 13115 Saint-Paul-Lez-Durance Cedex (France); Brethes, Daniel [CNRS, UMR 5095, Institut de Biochimie et Genetique Cellulaires, Universite Victor Segalen-Bordeaux 2 (France); Frelon, Sandrine; Floriani, Magali; Camilleri, Virginie; Garnier-Laplace, Jacqueline [Laboratoire de Radioecologie et d' Ecotoxicologie, Institut de Radioprotection et de Surete Nucleaire, Bat 186, BP 3, 13115 Saint-Paul-Lez-Durance Cedex (France); Bourdineaud, Jean-Paul, E-mail: jp.bourdineaud@epoc.u-bordeaux1.fr [CNRS, UMR 5095, Institut de Biochimie et Genetique Cellulaires, Universite Victor Segalen-Bordeaux 2 (France)

    2010-10-01

    Anthropogenic release of uranium (U), originating from the nuclear fuel cycle or military activities, may considerably increase U concentrations in terrestrial and aquatic ecosystems above the naturally occurring background levels found throughout the environment. With a projected increase in the world-wide use of nuclear power, it is important to improve our understanding of the possible effects of this metal on the aquatic fauna at concentrations commensurate with the provisional drinking water guideline value of the World Health Organization (15 {mu}g U/L). The present study has examined the mitochondrial function in brain and skeletal muscles of the zebrafish, Danio rerio, exposed to 30 and 100 {mu}g/L of waterborne U for 10 and 28 days. At the lower concentration, the basal mitochondrial respiration rate was increased in brain at day 10 and in muscles at day 28. This is due to an increase of the inner mitochondrial membrane permeability, resulting in a decrease of the respiratory control ratio. In addition, levels of cytochrome c oxidase subunit IV (COX-IV) increased in brain at day 10, and those of COX-I increased in muscles at day 28. Histological analyses performed by transmission electron microscopy revealed an alteration of myofibrils and a dilatation of endomysium in muscle cells. These effects were largest at the lowest concentration, following 28 days of exposure.

  10. Role of insulin on exercise-induced GLUT-4 protein expression and glycogen supercompensation in rat skeletal muscle.

    Science.gov (United States)

    Kuo, Chia-Hua; Hwang, Hyonson; Lee, Man-Cheong; Castle, Arthur L; Ivy, John L

    2004-02-01

    The purpose of this study was to investigate the role of insulin on skeletal muscle GLUT-4 protein expression and glycogen storage after postexercise carbohydrate supplementation. Male Sprague-Dawley rats were randomly assigned to one of six treatment groups: sedentary control (Con), Con with streptozocin (Stz/C), immediately postexercise (Ex0), Ex0 with Stz (Stz/Ex0), 5-h postexercise (Ex5), and Ex5 with Stz (Stz/Ex5). Rats were exercised by swimming (2 bouts of 3 h) and carbohydrate supplemented immediately after each exercise session by glucose intubation (1 ml of a 50% wt/vol). Stz was administered 72-h before exercise, which resulted in hyperglycemia and elimination of the insulin response to the carbohydrate supplement. GLUT-4 protein of Ex0 rats was 30% above Con in fast-twitch (FT) red and 21% above Con in FT white muscle. In Ex5, GLUT-4 protein was 52% above Con in FT red and 47% above Con in FT white muscle. Muscle glycogen in FT red and white muscle was also increased above Con in Ex5 rats. Neither GLUT-4 protein nor muscle glycogen was increased above Con in Stz/Ex0 or Stz/Ex5 rats. GLUT-4 mRNA in FT red muscle of Ex0 rats was 61% above Con but only 33% above Con in Ex5 rats. GLUT-4 mRNA in FT red muscle of Stz/C and Stz/Ex0 rats was similar but significantly elevated in Ex5/Stz rats. These results suggest that insulin is essential for the increase in GLUT-4 protein expression following postexercise carbohydrate supplementation.

  11. Effects of hyperthyroidism and hypothyroidism on glutamine metabolism by skeletal muscle of the rat.

    Science.gov (United States)

    Parry-Billings, M; Dimitriadis, G D; Leighton, B; Bond, J; Bevan, S J; Opara, E; Newsholme, E A

    1990-01-01

    1. The effects of hyperthyroidism and hypothyroidism on the concentrations of glutamine and other amino acids in the muscle and plasma and on the rates of glutamine and alanine release from incubated isolated stripped soleus muscle of the rat were investigated. 2. Hyperthyroidism decreased the concentration of glutamine in soleus muscle but was without effect on that in the gastrocnemius muscle or in the plasma. Hyperthyroidism also increased markedly the rate of release of glutamine from the incubated soleus muscle. 3. Hypothyroidism decreased the concentrations of glutamine in the gastrocnemius muscle and plasma but was without effect on that in soleus muscle. Hypothyroidism also decreased markedly the rate of glutamine release from the incubated soleus muscle. 4. Thyroid status was found to have marked effects on the rate of glutamine release by skeletal muscle per se, and may be important in the control of this process in both physiological and pathological conditions. PMID:2268261

  12. β-Hydroxy-β-methylbutyrate (HMβ supplementation stimulates skeletal muscle hypertrophy in rats via the mTOR pathway

    Directory of Open Access Journals (Sweden)

    Pimentel Gustavo D

    2011-02-01

    Full Text Available Abstract β-Hydroxy-β-methylbutyrate (HMβ supplementation is used to treat cancer, sepsis and exercise-induced muscle damage. However, its effects on animal and human health and the consequences of this treatment in other tissues (e.g., fat and liver have not been examined. The purpose of this study was to evaluate the effects of HMβ supplementation on skeletal muscle hypertrophy and the expression of proteins involved in insulin signalling. Rats were treated with HMβ (320 mg/kg body weight or saline for one month. The skeletal muscle hypertrophy and insulin signalling were evaluated by western blotting, and hormonal concentrations were evaluated using ELISAs. HMβ supplementation induced muscle hypertrophy in the extensor digitorum longus (EDL and soleus muscles and increased serum insulin levels, the expression of the mammalian target of rapamycin (mTOR and phosphorylation of p70S6K in the EDL muscle. Expression of the insulin receptor was increased only in liver. Thus, our results suggest that HMβ supplementation can be used to increase muscle mass without adverse health effects.

  13. Acute Exercise Induced Mitochondrial H2O2 Production in Mouse Skeletal Muscle: Association with p66Shc and FOXO3a Signaling and Antioxidant Enzymes

    Directory of Open Access Journals (Sweden)

    Ping Wang

    2015-01-01

    Full Text Available Exercise induced skeletal muscle phenotype change involves a complex interplay between signaling pathways and downstream regulators. This study aims to investigate the effect of acute exercise on mitochondrial H2O2 production and its association with p66Shc, FOXO3a, and antioxidant enzymes. Male ICR/CD-1 mice were subjected to an acute exercise. Muscle tissues (gastrocnemius and quadriceps femoris were taken after exercise to measure mitochondrial H2O2 content, expression of p66Shc and FOXO3a, and the activity of antioxidant enzymes. The results showed that acute exercise significantly increased mitochondrial H2O2 content and expressions of p66Shc and FOXO3a in a time-dependent manner, with a linear correlation between the increase in H2O2 content and p66Shc or FOXO3a expression. The activity of mitochondrial catalase was slightly reduced in the 90 min exercise group, but it was significantly higher in groups with 120 and 150 min exercise compared to that of 90 min exercise group. The activity of SOD was not significantly affected. The results indicate that acute exercise increases mitochondrial H2O2 production in the skeletal muscle, which is associated with the upregulation of p66Shc and FOXO3a. The association of p66Shc and FOXO3a signaling with exercise induced H2O2 generation may play a role in regulating cellular oxidative stress during acute exercise.

  14. Protein Availability and Satellite Cell Dynamics in Skeletal Muscle.

    Science.gov (United States)

    Shamim, Baubak; Hawley, John A; Camera, Donny M

    2018-06-01

    Human skeletal muscle satellite cells are activated in response to both resistance and endurance exercise. It was initially proposed that satellite cell proliferation and differentiation were only required to support resistance exercise-induced hypertrophy. However, satellite cells may also play a role in muscle fibre remodelling after endurance-based exercise and extracellular matrix regulation. Given the importance of dietary protein, particularly branched chain amino acids, in supporting myofibrillar and mitochondrial adaptations to both resistance and endurance-based training, a greater understanding of how protein intake impacts satellite cell activity would provide further insight into the mechanisms governing skeletal muscle remodelling with exercise. While many studies have investigated the capacity for protein ingestion to increase post-exercise rates of muscle protein synthesis, few investigations have examined the role for protein ingestion to modulate satellite cell activity. Here we review the molecular mechanisms controlling the activation of satellite cells in response to mechanical stress and protein intake in both in vitro and in vivo models. We provide a mechanistic framework that describes how protein ingestion may enhance satellite activity and promote exercise adaptations in human skeletal muscle.

  15. Two weeks of one-leg immobilization decreases skeletal muscle respiratory capacity equally in young and elderly men

    DEFF Research Database (Denmark)

    Gram, Martin; Vigelsø Hansen, Andreas; Yokota, Takashi

    2014-01-01

    Physical inactivity affects human skeletal muscle mitochondrial oxidative capacity but the influence of aging combined with physical inactivity is not known. This study investigates the effect of two weeks of immobilization followed by six weeks of supervised cycle training on muscle oxidative...... capacity in 17 young (23±1years) and 15 elderly (68±1years) healthy men. We applied high-resolution respirometry in permeabilized fibers from muscle biopsies at inclusion after immobilization and training. Furthermore, protein content of mitochondrial complexes I-V, mitochondrial heat shock protein 70 (mt......HSP70) and voltage dependent anion channel (VDAC) were measured in skeletal muscle by Western blotting. The elderly men had lower content of complexes I-V and mtHSP70 but similar respiratory capacity and content of VDAC compared to the young. In both groups the respiratory capacity and protein content...

  16. Long-term skeletal muscle mitochondrial dysfunction is associated with hypermetabolism in severely burned children

    Science.gov (United States)

    The long-term impact of burn trauma on skeletal muscle bioenergetics remains unknown. Here, we determined respiratory capacity and function of skeletal muscle mitochondria in healthy individuals and in burn victims for up to two years post-injury. Biopsies were collected from the m. vastus lateralis...

  17. De novo synthesis of purine nucleotides in different fiber types of rat skeletal muscle

    International Nuclear Information System (INIS)

    Tullson, P.C.; John-Alder, H.; Hood, D.A.; Terjung, R.L.

    1986-01-01

    The contribution of de novo purine nucleotide synthesis to nucleotide metabolism in skeletal muscles is not known. The authors have determined rates of de novo synthesis in soleus (slow-twitch red), red gastrocnemius (fast-twitch red), and white gastrocnemius (fast-twitch white) using the perfused rat hindquarter. 14 C glycine incorporation into ATP was linear after 1 and 2 hours of perfusion with 0.2 mM added glycine. The intracellular (I) and extracellular (E) specific activity of 14 C glycine was determined by HPLC of phenylisothiocyanate derivatives of neutralized PCA extracts. The rates of de novo synthesis when expressed relative to muscle ATP content show slow and fast-twitch red muscles to be similar and about twice as great as fast-twitch white muscles. This could represent a greater turnover of the adenine nucleotide pool in more oxidative red muscle types

  18. Dose Response of Endotoxin on Hepatocyte and Muscle Mitochondrial Respiration In Vitro

    Science.gov (United States)

    Brandt, Sebastian; Porta, Francesca; Jakob, Stephan M.; Takala, Jukka; Djafarzadeh, Siamak

    2015-01-01

    Introduction. Results on mitochondrial dysfunction in sepsis are controversial. We aimed to assess effects of LPS at wide dose and time ranges on hepatocytes and isolated skeletal muscle mitochondria. Methods. Human hepatocellular carcinoma cells (HepG2) were exposed to placebo or LPS (0.1, 1, and 10 μg/mL) for 4, 8, 16, and 24 hours and primary human hepatocytes to 1 μg/mL LPS or placebo (4, 8, and 16 hours). Mitochondria from porcine skeletal muscle samples were exposed to increasing doses of LPS (0.1–100 μg/mg) for 2 and 4 hours. Respiration rates of intact and permeabilized cells and isolated mitochondria were measured by high-resolution respirometry. Results. In HepG2 cells, LPS reduced mitochondrial membrane potential and cellular ATP content but did not modify basal respiration. Stimulated complex II respiration was reduced time-dependently using 1 μg/mL LPS. In primary human hepatocytes, stimulated mitochondrial complex II respiration was reduced time-dependently using 1 μg/mL LPS. In isolated porcine skeletal muscle mitochondria, stimulated respiration decreased at high doses (50 and 100 μg/mL LPS). Conclusion. LPS reduced cellular ATP content of HepG2 cells, most likely as a result of the induced decrease in membrane potential. LPS decreased cellular and isolated mitochondrial respiration in a time-dependent, dose-dependent and complex-dependent manner. PMID:25649304

  19. Hyperbaric oxygen in skeletal muscle of rats submitted to total acute left hindlimb ischemia: A research report.

    Science.gov (United States)

    da Silva, Luis Gustavo Campos; Dalio, Marcelo Bellini; Joviliano, Edwaldo Edner; Feres, Omar; Piccinato, Carlos Eli

    2015-01-01

    Determine the effect of hyperbaric oxygen treatment in skeletal muscle of rats submitted to total acute left hindlimb ischemia. An experimental study was designed using 48 Wistar rats divided into four groups (n = 12): Control; Ischemia (I)--total hindlimb ischemia for 270 minutes; Hyperbaric oxygen treatment during ischemia (HBO2)--total hindlimb ischemia for 270 minutes and hyperbaric oxygen during the first 90 minutes; Pre-treatment with hyperbaric oxygen (PHBO2)--90 minutes of hyperbaric oxygen treatment before total hindlimb ischemia for 270 minutes. Skeletal muscle injury was evaluated by measuring levels of aspartate aminotransferase (AST), lactate dehydrogenase (LDH), total creatine phosphokinase (CPK); muscular malondialdehyde (MDA), muscular glycogen, and serum ischemia-modified albumin (IMA). AST was significantly higher in I, HBO2 and PHBO2 compared with control (P = .001). There was no difference in LDH. CPK was significantly higher in I, HBO2 and PHBO2, compared with control (p = .014). MDA was significantly higher in PHBO2, compared with other groups (p = .042). Glycogen was significantly decreased in I, HBO2 and PHBO2, compared with control (p < .001). Hyperbaric oxygen treatment in acute total hindlimb ischemia exerted no protective effect on muscle injury, regardless of time of application. When applied prior to installation of total ischemia, hyperbaric oxygen treatment aggravated muscle injury.

  20. Effect of testosterone on markers of mitochondrial oxidative phosphorylation and lipid metabolism in muscle of aging men with subnormal bioavailable testosterone

    DEFF Research Database (Denmark)

    Petersson, Stine J; Christensen, Louise L; Kristensen, Jonas M

    2014-01-01

    therapy on regulators of mitochondrial biogenesis and markers of OxPhos and lipid metabolism in the skeletal muscle of aging men with subnormal bioavailable testosterone levels. METHODS: Skeletal muscle biopsies were obtained before and after treatment with either testosterone gel (n=12) or placebo (n=13......) for 6 months. Insulin sensitivity and substrate oxidation were assessed by euglycemic-hyperinsulinemic clamp and indirect calorimetry. Muscle mRNA levels and protein abundance and phosphorylation of enzymes involved in mitochondrial biogenesis, OxPhos, and lipid metabolism were examined by quantitative......: The beneficial effect of testosterone treatment on lipid oxidation is not explained by increased abundance or phosphorylation-dependent activity of enzymes known to regulate mitochondrial biogenesis or markers of OxPhos and lipid metabolism in the skeletal muscle of aging men with subnormal bioavailable...

  1. Proteomics of Skeletal Muscle

    DEFF Research Database (Denmark)

    Deshmukh, Atul

    2016-01-01

    , of altered protein expressions profiles and/or their posttranslational modifications (PTMs). Mass spectrometry (MS)-based proteomics offer enormous promise for investigating the molecular mechanisms underlying skeletal muscle insulin resistance and exercise-induced adaptation; however, skeletal muscle......Skeletal muscle is the largest tissue in the human body and plays an important role in locomotion and whole body metabolism. It accounts for ~80% of insulin stimulated glucose disposal. Skeletal muscle insulin resistance, a primary feature of Type 2 diabetes, is caused by a decreased ability...... of muscle to respond to circulating insulin. Physical exercise improves insulin sensitivity and whole body metabolism and remains one of the most promising interventions for the prevention of Type 2 diabetes. Insulin resistance and exercise adaptations in skeletal muscle might be a cause, or consequence...

  2. Identification of telocytes in skeletal muscle interstitium: implication for muscle regeneration.

    Science.gov (United States)

    Popescu, L M; Manole, Emilia; Serboiu, Crenguţa S; Manole, C G; Suciu, Laura C; Gherghiceanu, Mihaela; Popescu, B O

    2011-06-01

    Skeletal muscle interstitium is crucial for regulation of blood flow, passage of substances from capillaries to myocytes and muscle regeneration. We show here, probably, for the first time, the presence of telocytes (TCs), a peculiar type of interstitial (stromal) cells, in rat, mouse and human skeletal muscle. TC features include (as already described in other tissues) a small cell body and very long and thin cell prolongations-telopodes (Tps) with moniliform appearance, dichotomous branching and 3D-network distribution. Transmission electron microscopy (TEM) revealed close vicinity of Tps with nerve endings, capillaries, satellite cells and myocytes, suggesting a TC role in intercellular signalling (via shed vesicles or exosomes). In situ immunolabelling showed that skeletal muscle TCs express c-kit, caveolin-1 and secrete VEGF. The same phenotypic profile was demonstrated in cell cultures. These markers and TEM data differentiate TCs from both satellite cells (e.g. TCs are Pax7 negative) and fibroblasts (which are c-kit negative). We also described non-satellite (resident) progenitor cell niche. In culture, TCs (but not satellite cells) emerge from muscle explants and form networks suggesting a key role in muscle regeneration and repair, at least after trauma. © 2011 The Authors Journal of Cellular and Molecular Medicine © 2011 Foundation for Cellular and Molecular Medicine/Blackwell Publishing Ltd.

  3. Skeletal muscle atrophy in bioengineered skeletal muscle: a new model system.

    Science.gov (United States)

    Lee, Peter H U; Vandenburgh, Herman H

    2013-10-01

    Skeletal muscle atrophy has been well characterized in various animal models, and while certain pathways that lead to disuse atrophy and its associated functional deficits have been well studied, available drugs to counteract these deficiencies are limited. An ex vivo tissue-engineered skeletal muscle offers a unique opportunity to study skeletal muscle physiology in a controlled in vitro setting. Primary mouse myoblasts isolated from adult muscle were tissue engineered into bioartificial muscles (BAMs) containing hundreds of aligned postmitotic muscle fibers expressing sarcomeric proteins. When electrically stimulated, BAMs generated measureable active forces within 2-3 days of formation. The maximum isometric tetanic force (Po) increased for ∼3 weeks to 2587±502 μN/BAM and was maintained at this level for greater than 80 days. When BAMs were reduced in length by 25% to 50%, muscle atrophy occurred in as little as 6 days. Length reduction resulted in significant decreases in Po (50.4%), mean myofiber cross-sectional area (21.7%), total protein synthesis rate (22.0%), and noncollagenous protein content (6.9%). No significant changes occurred in either the total metabolic activity or protein degradation rates. This study is the first in vitro demonstration that length reduction alone can induce skeletal muscle atrophy, and establishes a novel in vitro model for the study of skeletal muscle atrophy.

  4. Nonshivering thermogenesis in king penguin chicks. I. Role of skeletal muscle.

    Science.gov (United States)

    Duchamp, C; Barré, H; Rouanet, J L; Lanni, A; Cohen-Adad, F; Berne, G; Brebion, P

    1991-12-01

    In cold-acclimatized (CA) king penguin chicks exhibiting nonshivering thermogenesis (NST), protein content and cytochrome oxidase (CO) activity of tissue homogenates were measured together with protein content, CO, and respiration rates of isolated mitochondria from skeletal muscle (gastrocnemius and pectoralis) and liver. The comparison was made with chicks reared at thermoneutrality (TN) for at least 3 wk. In CA chicks showing a NST despite the lack of brown adipose tissue, an increase in thermogenic capacity was observed in skeletal muscle in which the oxidative capacity rose (+28% and +50% in gastrocnemius and pectoralis muscles, respectively), whereas no change occurred in the liver. Oxidative capacity of skeletal muscle increased together with the development of mitochondrial inner membrane plus cristae in muscles of CA chicks contrary to their TN littermates (+30 to +50%). Subsarcolemmal mitochondria of CA chicks had a higher protein content (+65% in gastrocnemius muscle) and higher oxidative capacities than in controls. The lower respiratory control ratio of these mitochondria might result from a low ADP phosphorylation rate. No change occurred in the intermyofibrillar fraction nor in liver mitochondria. These findings together with earlier results obtained in cold-acclimated ducklings indicate the marked and suited adaptation of skeletal muscle and in particular of subsarcolemmal mitochondria allowing them to play a role in NST.

  5. Expression of Na+/HCO3- co-transporter proteins (NBCs) in rat and human skeletal muscle

    DEFF Research Database (Denmark)

    Kristensen, Jonas Møller; Kristensen, Michael; Juel, Carsten

    2004-01-01

    AIM: Sodium/bicarbonate co-transport (NBC) has been suggested to have a role in muscle pH regulation. We investigated the presence of NBC proteins in rat and human muscle samples and the fibre type distribution of the identified NBCs. METHODS AND RESULTS: Western blotting of muscle homogenates...... the T-tubules. The two NBCs localized in muscle have distinct fibre type distributions. CONCLUSIONS: Skeletal muscle possesses two variants of the sodium/bicarbonate co-transporter (NBC) isoforms, which have been called NBCe1 and NBCe2....... and sarcolemmal membranes (sarcolemmal giant vesicles) were used to screen for the presence of NBCs. Immunohistochemistry was used for the subcellular localization. The functional test revealed that approximately half of the pH recovery in sarcolemmal vesicles produced from rat muscle is mediated by bicarbonate...

  6. No effect of NOS inhibition on skeletal muscle glucose uptake during in situ hindlimb contraction in healthy and diabetic Sprague-Dawley rats.

    Science.gov (United States)

    Hong, Yet Hoi; Betik, Andrew C; Premilovac, Dino; Dwyer, Renee M; Keske, Michelle A; Rattigan, Stephen; McConell, Glenn K

    2015-05-15

    Nitric oxide (NO) has been shown to be involved in skeletal muscle glucose uptake during contraction/exercise, especially in individuals with Type 2 diabetes (T2D). To examine the potential mechanisms, we examined the effect of local NO synthase (NOS) inhibition on muscle glucose uptake and muscle capillary blood flow during contraction in healthy and T2D rats. T2D was induced in Sprague-Dawley rats using a combined high-fat diet (23% fat wt/wt for 4 wk) and low-dose streptozotocin injections (35 mg/kg). Anesthetized animals had one hindlimb stimulated to contract in situ for 30 min (2 Hz, 0.1 ms, 35 V) with the contralateral hindlimb rested. After 10 min, the NOS inhibitor, N(G)-nitro-l-arginine methyl ester (l-NAME; 5 μM) or saline was continuously infused into the femoral artery of the contracting hindlimb until the end of contraction. Surprisingly, there was no increase in skeletal muscle NOS activity during contraction in either group. Local NOS inhibition had no effect on systemic blood pressure or muscle contraction force, but it did cause a significant attenuation of the increase in femoral artery blood flow in control and T2D rats. However, NOS inhibition did not attenuate the increase in muscle capillary recruitment during contraction in these rats. Muscle glucose uptake during contraction was significantly higher in T2D rats compared with controls but, unlike our previous findings in hooded Wistar rats, NOS inhibition had no effect on glucose uptake during contraction. In conclusion, NOS inhibition did not affect muscle glucose uptake during contraction in control or T2D Sprague-Dawley rats, and this may have been because there was no increase in NOS activity during contraction. Copyright © 2015 the American Physiological Society.

  7. Transcriptomic profiling of TK2 deficient human skeletal muscle suggests a role for the p53 signalling pathway and identifies growth and differentiation factor-15 as a potential novel biomarker for mitochondrial myopathies

    Science.gov (United States)

    2014-01-01

    Background Mutations in the gene encoding thymidine kinase 2 (TK2) result in the myopathic form of mitochondrial DNA depletion syndrome which is a mitochondrial encephalomyopathy presenting in children. In order to unveil some of the mechanisms involved in this pathology and to identify potential biomarkers and therapeutic targets we have investigated the gene expression profile of human skeletal muscle deficient for TK2 using cDNA microarrays. Results We have analysed the whole transcriptome of skeletal muscle from patients with TK2 mutations and compared it to normal muscle and to muscle from patients with other mitochondrial myopathies. We have identified a set of over 700 genes which are differentially expressed in TK2 deficient muscle. Bioinformatics analysis reveals important changes in muscle metabolism, in particular, in glucose and glycogen utilisation, and activation of the starvation response which affects aminoacid and lipid metabolism. We have identified those transcriptional regulators which are likely to be responsible for the observed changes in gene expression. Conclusion Our data point towards the tumor suppressor p53 as the regulator at the centre of a network of genes which are responsible for a coordinated response to TK2 mutations which involves inflammation, activation of muscle cell death by apoptosis and induction of growth and differentiation factor 15 (GDF-15) in muscle and serum. We propose that GDF-15 may represent a potential novel biomarker for mitochondrial dysfunction although further studies are required. PMID:24484525

  8. Markers of Skeletal Muscle Mitochondrial Function and Lipid Accumulation Are Moderately Associated with the Homeostasis Model Assessment Index of Insulin Resistance in Obese Men

    Science.gov (United States)

    Samjoo, Imtiaz A.; Safdar, Adeel; Hamadeh, Mazen J.; Glover, Alexander W.; Mocellin, Nicholas J.; Santana, Jose; Little, Jonathan P.; Steinberg, Gregory R.; Raha, Sandeep; Tarnopolsky, Mark A.

    2013-01-01

    Lower skeletal muscle mitochondrial oxidative phosphorylation capacity (OXPHOS) and intramyocellular lipid (IMCL) accumulation have been implicated in the etiology of insulin resistance (IR) in obesity. The purpose of this study was to examine the impact of endurance exercise on biochemical and morphological measures of IMCL and mitochondrial content, and their relationship to IR in obese individuals. We examined mitochondrial content (subunit protein abundance and maximal activity of electron transport chain enzymes), IMCL/mitochondrial morphology in both subsarcolemmal (SS) and intermyofibrillar (IMF) regions by transmission electron microscopy, and intracellular lipid metabolites (diacylglycerol and ceramide) in vastus lateralis biopsies, as well as, the homeostasis model assessment index of IR (HOMA-IR) prior to and following twelve weeks of an endurance exercise regimen in healthy age- and physical activity-matched lean and obese men. Obese men did not show evidence of mitochondrial OXPHOS dysfunction, disproportionate IMCL content in sub-cellular regions, or diacylglycerol/ceramide accretion despite marked IR vs. lean controls. Endurance exercise increased OXPHOS and mitochondrial size and density, but not number of individual mitochondrial fragments, with moderate improvements in HOMA-IR. Exercise reduced SS IMCL content (size, number and density), increased IMF IMCL content, while increasing IMCL/mitochondrial juxtaposition in both regions. HOMA-IR was inversely associated with SS (r = −0.34; P = 0.051) and IMF mitochondrial density (r = −0.29; P = 0.096), IMF IMCL/mitochondrial juxtaposition (r = −0.30; P = 0.086), and COXII (r = −0.32; P = 0.095) and COXIV protein abundance (r = −0.35; P = 0.052); while positively associated with SS IMCL size (r = 0.28; P = 0.119) and SS IMCL density (r = 0.25; P = 0.152). Our findings suggest that once physical activity and cardiorespiratory fitness have

  9. Markers of skeletal muscle mitochondrial function and lipid accumulation are moderately associated with the homeostasis model assessment index of insulin resistance in obese men.

    Directory of Open Access Journals (Sweden)

    Imtiaz A Samjoo

    Full Text Available Lower skeletal muscle mitochondrial oxidative phosphorylation capacity (OXPHOS and intramyocellular lipid (IMCL accumulation have been implicated in the etiology of insulin resistance (IR in obesity. The purpose of this study was to examine the impact of endurance exercise on biochemical and morphological measures of IMCL and mitochondrial content, and their relationship to IR in obese individuals. We examined mitochondrial content (subunit protein abundance and maximal activity of electron transport chain enzymes, IMCL/mitochondrial morphology in both subsarcolemmal (SS and intermyofibrillar (IMF regions by transmission electron microscopy, and intracellular lipid metabolites (diacylglycerol and ceramide in vastus lateralis biopsies, as well as, the homeostasis model assessment index of IR (HOMA-IR prior to and following twelve weeks of an endurance exercise regimen in healthy age- and physical activity-matched lean and obese men. Obese men did not show evidence of mitochondrial OXPHOS dysfunction, disproportionate IMCL content in sub-cellular regions, or diacylglycerol/ceramide accretion despite marked IR vs. lean controls. Endurance exercise increased OXPHOS and mitochondrial size and density, but not number of individual mitochondrial fragments, with moderate improvements in HOMA-IR. Exercise reduced SS IMCL content (size, number and density, increased IMF IMCL content, while increasing IMCL/mitochondrial juxtaposition in both regions. HOMA-IR was inversely associated with SS (r = -0.34; P = 0.051 and IMF mitochondrial density (r = -0.29; P = 0.096, IMF IMCL/mitochondrial juxtaposition (r = -0.30; P = 0.086, and COXII (r = -0.32; P = 0.095 and COXIV protein abundance (r = -0.35; P = 0.052; while positively associated with SS IMCL size (r = 0.28; P = 0.119 and SS IMCL density (r = 0.25; P = 0.152. Our findings suggest that once physical activity and cardiorespiratory fitness have been

  10. Changes in skeletal muscle and tendon structure and function following genetic inactivation of myostatin in rats

    Science.gov (United States)

    Mendias, Christopher L; Lynch, Evan B; Gumucio, Jonathan P; Flood, Michael D; Rittman, Danielle S; Van Pelt, Douglas W; Roche, Stuart M; Davis, Carol S

    2015-01-01

    Myostatin is a negative regulator of skeletal muscle and tendon mass. Myostatin deficiency has been well studied in mice, but limited data are available on how myostatin regulates the structure and function of muscles and tendons of larger animals. We hypothesized that, in comparison to wild-type (MSTN+/+) rats, rats in which zinc finger nucleases were used to genetically inactivate myostatin (MSTNΔ/Δ) would exhibit an increase in muscle mass and total force production, a reduction in specific force, an accumulation of type II fibres and a decrease and stiffening of connective tissue. Overall, the muscle and tendon phenotype of myostatin-deficient rats was markedly different from that of myostatin-deficient mice, which have impaired contractility and pathological changes to fibres and their extracellular matrix. Extensor digitorum longus and soleus muscles of MSTNΔ/Δ rats demonstrated 20–33% increases in mass, 35–45% increases in fibre number, 20–57% increases in isometric force and no differences in specific force. The insulin-like growth factor-1 pathway was activated to a greater extent in MSTNΔ/Δ muscles, but no substantial differences in atrophy-related genes were observed. Tendons of MSTNΔ/Δ rats had a 20% reduction in peak strain, with no differences in mass, peak stress or stiffness. The general morphology and gene expression patterns were similar between tendons of both genotypes. This large rodent model of myostatin deficiency did not have the negative consequences to muscle fibres and extracellular matrix observed in mouse models, and suggests that the greatest impact of myostatin in the regulation of muscle mass may not be to induce atrophy directly, but rather to block hypertrophy signalling. PMID:25640143

  11. Energy conservation attenuates the loss of skeletal muscle excitability during intense contractions

    DEFF Research Database (Denmark)

    Macdonald, W A; Ørtenblad, N; Nielsen, Ole Bækgaard

    2007-01-01

    High-frequency stimulation of skeletal muscle has long been associated with ionic perturbations, resulting in the loss of membrane excitability, which may prevent action potential propagation and result in skeletal muscle fatigue. Associated with intense skeletal muscle contractions are large...... with control muscles, the resting metabolites ATP, phosphocreatine, creatine, and lactate, as well as the resting muscle excitability as measured by M-waves, were unaffected by treatment with BTS plus dantrolene. Following 20 or 30 s of continuous 60-Hz stimulation, BTS-plus-dantrolene-treated muscles showed...... changes in muscle metabolites. However, the role of metabolites in the loss of muscle excitability is not clear. The metabolic state of isolated rat extensor digitorum longus muscles at 30 degrees C was manipulated by decreasing energy expenditure and thereby allowed investigation of the effects of energy...

  12. Wortmannin inhibits both insulin- and contraction-stimulated glucose uptake and transport in rat skeletal muscle

    DEFF Research Database (Denmark)

    Wojtaszewski, Jørgen; Hansen, B F; Ursø, Birgitte

    1996-01-01

    The role of phosphatidylinositol (PI) 3-kinase for insulin- and contraction-stimulated muscle glucose transport was investigated in rat skeletal muscle perfused with a cell-free perfusate. The insulin receptor substrate-1-associated PI 3-kinase activity was increased sixfold upon insulin...... stimulation but was unaffected by contractions. In addition, the insulin-stimulated PI 3-kinase activity and muscle glucose uptake and transport in individual muscles were dose-dependently inhibited by wortmannin with one-half maximal inhibition values of approximately 10 nM and total inhibition at 1 micro......M. This concentration of wortmannin also decreased the contraction-stimulated glucose transport and uptake by approximately 30-70% without confounding effects on contractility or on muscle ATP and phosphocreatine concentrations. At higher concentrations (3 and 10 microM), wortmannin completely blocked the contraction...

  13. Effect of in vivo injection of cholera and pertussis toxin on glucose transport in rat skeletal muscle

    DEFF Research Database (Denmark)

    Ploug, Thorkil; Han, X; Petersen, L N

    1997-01-01

    Cholera toxin (CTX) and pertussis toxin (PTX) were examined for their ability to inhibit glucose transport in perfused skeletal muscle. Twenty-five hours after an intravenous injection of CTX, basal transport was decreased approximately 30%, and insulin- and contraction-stimulated transport...... in GLUT-1 protein content was found. In contrast, GLUT-4 mRNA was unchanged, but transcripts for GLUT-1 were increased > or = 150% in all three muscles from CTX-treated rats. The findings suggest that CTX via increased cAMP impairs basal as well as insulin- and contraction-stimulated muscle glucose...

  14. Increased Autolysis of μ-Calpain in Skeletal Muscles of Chronic Alcohol-Fed Rats.

    Science.gov (United States)

    Gritsyna, Yulia V; Salmov, Nikolay N; Bobylev, Alexander G; Ulanova, Anna D; Kukushkin, Nikolay I; Podlubnaya, Zoya A; Vikhlyantsev, Ivan M

    2017-10-01

    Proteolysis can proceed via several distinct pathways such as the lysosomal, calcium-dependent, and ubiquitin-proteasome-dependent pathways. Calpains are the main proteases that cleave a large variety of proteins, including the giant sarcomeric proteins, titin and nebulin. Chronic ethanol feeding for 6 weeks did not affect the activities of μ-calpain and m-calpain in the m. gastrocnemius. In our research, changes in μ-calpain activity were studied in the m. gastrocnemius and m. soleus of chronically alcohol-fed rats after 6 months of alcohol intake. SDS-PAGE analysis was applied to detect changes in titin and nebulin contents. Titin phosphorylation analysis was performed using the fluorescent dye Pro-Q Diamond. Western blotting was used to determine μ-calpain autolysis as well as μ-calpain and calpastatin contents. The titin and nebulin mRNA levels were assessed by real-time PCR. The amounts of the autolysed isoform (78 kDa) of full-length μ-calpain (80 kDa) increased in the m. gastrocnemius and m. soleus of alcohol-fed rats. The calpastatin content increased in m. gastrocnemius. Decreased intact titin-1 (T1) and increased T2-proteolytic fragment contents were found in the m. gastrocnemius and m. soleus of the alcohol-fed rats. The nebulin content decreased in the rat gastrocnemius muscle of the alcohol-fed group. The phosphorylation levels of T1 and T2 were increased in the m. gastrocnemius and m. soleus, and decreased titin and nebulin mRNA levels were observed in the m. gastrocnemius. The nebulin mRNA level was increased in the soleus muscle of the alcohol-fed rats. In summary, our data suggest that prolonged chronic alcohol consumption for 6 months resulted in increased autolysis of μ-calpain in rat skeletal muscles. These changes were accompanied by reduced titin and nebulin contents, titin hyperphosphorylation, and development of hindlimb muscle atrophy in the alcohol-fed rats. Copyright © 2017 by the Research Society on Alcoholism.

  15. Alteration of gene expression profiles in skeletal muscle of rats exposed to microgravity during a spaceflight

    Science.gov (United States)

    Taylor, Wayne E.; Bhasin, Shalender; Lalani, Rukhsana; Datta, Anuj; Gonzalez-Cadavid, Nestor F.

    2002-01-01

    To clarify the mechanism of skeletal muscle wasting during spaceflights, we investigated whether intramuscular gene expression profiles are affected, by using DNA microarray methods. Male rats sent on the 17-day NASA STS-90 Neurolab spaceflight were sacrificed 24 hours after return to earth (MG group). Ground control rats were maintained for 17 days in flight-simulated cages (CS group). Spaceflight induced a 19% and 23% loss of tibialis anterior and gastrocnemius muscle mass, respectively, as compared to ground controls. Muscle RNA was analyzed by the Clontech Atlas DNA expression array in four rats, with two MG/ CS pairs for the tibialis anterior, and one pair for the gastrocnemius. Alterations in gene expression were verified for selected genes by reverse-transcription PCR. In both muscles of MG rats, mRNAs for 12 genes were up-regulated by over 2-fold, and 38 were down-regulated compared to controls. There was inhibition of genes for cell proliferation and growth factor cascades, including cell cycle genes and signal transduction proteins, such as p21 Cip1, retinoblastoma (Rb), cyclins G1/S, -E and -D3, MAP kinase 3, MAD3, and ras related protein RAB2. These data indicate that following exposure to microgravity, there is downregulation of genes involved in regulation of muscle satellite cell replication.

  16. Comparative in vitro metabolism of 1-14C-oleic acid and 1-14C-erucic acid in liver, heart and skeletal muscles of rats

    International Nuclear Information System (INIS)

    Bhatia, I.S.; Sharma, A.K.; Ahuja, S.P.

    1978-01-01

    In vitro oxidation of 14 C-oleic and 1- 14 C-erucic acid and their incorporation into lipids by liver, heart and skeletal muscles from female albino rats were studied. These tissues were obtained from rats maintained for 120 days on low fat diet or diets containing 15% mustard oil or 15% groundnut oil. In all these tissues from rats on different types of diets, the oxidation of 1- 14 C-erucic acid was lower than that 1- 14 C-oleic acid. There was little accumulation of lipids in heart after 120 days of feeding mustard oil. Oxidation of 1- 14 C-erucic acid was enhanced in liver, heart and skeletal muscles of rats conditioned to the mustard oil diet supplying erucic acid. Oxidation of erucic acid was maximum in liver and least in heart, whereas there were no differences in the oxidation of 1- 14 C-oleic acid in these tissues. Incorporation of 1- 14 C-oleic acid into triglycerides and phospholipids was not affected by the type of diet or tissues Incorporation of 1- 14 C-erucic acid was mainly into triglycerides of heart and skeletal muscles of rats not accustomed to mustard oil diet whereas these tissues from rats accustomed to mustard oil diets incorporated 1- 14 C-erucic acid both into the triglycerides and phospholipids. (author)

  17. Effects of Dioscorea esculenta and Eubacterium rectale on insulin receptor substrate 1 (Irs1 Expression in skeletal muscle and homeostatic model assessment-insulin resistance (HOMA-IR in diabetic rats

    Directory of Open Access Journals (Sweden)

    . Sunarti

    2017-01-01

    Full Text Available Low expression of insulin receptor substrate 1 (Irs1 is associated with insulin resistance and type 2 diabetes mellitus (type 2 DM. This study was performed to evaluate the effects of Dioscorea esculenta and Eubacterium rectale on the Irs1 expression in the skeletal muscle and the homeostatic model assessment-insulin resistance (HOMA-IR of diabetic rats. Twenty-five male Wistar rats were divided into five groups i.e. non diabetic rats Group 1; diabetic rats as Group 2; diabetic rats + D. esculenta as Group 3; diabetic rats + E.rectale as Group 4 and diabetic rats + both E. rectale and D. esculenta as Group 5. Rats were made diabetic with induction of intraperitoneally injection of nicotinamide and streptozotocin. After four weeks of the interventions, the blood and skeletal muscles were taken. The Irs1 expression was analyzed with immunohistochemical staining, plasma glucose levels was analyzed using a spectrophotometer, and insulin was analyzed using ELISA methods. All intervention groups reduced plasma glucose levels and HOMA-IRs (p<0.001 and increased Irs1 expression. The greatest reduction of  plasma glucose levels and increase of Irs1 expression in the skeletal muscle were found in Group 4, however, the lowest of HOMA-IR was seen in Group 5. These results suggested that D.esculenta, E.rectale, and the combination reduced plasma glucose levels and HOMA-IR by increasing Irs1 expression in skeletal muscle.

  18. The Skeletal Muscle Satellite Cell

    Science.gov (United States)

    2011-01-01

    The skeletal muscle satellite cell was first described and named based on its anatomic location between the myofiber plasma and basement membranes. In 1961, two independent studies by Alexander Mauro and Bernard Katz provided the first electron microscopic descriptions of satellite cells in frog and rat muscles. These cells were soon detected in other vertebrates and acquired candidacy as the source of myogenic cells needed for myofiber growth and repair throughout life. Cultures of isolated myofibers and, subsequently, transplantation of single myofibers demonstrated that satellite cells were myogenic progenitors. More recently, satellite cells were redefined as myogenic stem cells given their ability to self-renew in addition to producing differentiated progeny. Identification of distinctively expressed molecular markers, in particular Pax7, has facilitated detection of satellite cells using light microscopy. Notwithstanding the remarkable progress made since the discovery of satellite cells, researchers have looked for alternative cells with myogenic capacity that can potentially be used for whole body cell-based therapy of skeletal muscle. Yet, new studies show that inducible ablation of satellite cells in adult muscle impairs myofiber regeneration. Thus, on the 50th anniversary since its discovery, the satellite cell’s indispensable role in muscle repair has been reaffirmed. PMID:22147605

  19. Regulation of skeletal muscle mitochondrial activity by thyroid hormones: focus on "old" triiodothyronine and the "emerging" 3,5-diiodothyronine".

    Directory of Open Access Journals (Sweden)

    Assunta eLombardi

    2015-08-01

    Full Text Available 3,5,3'-triiodo-L-thyronine (T3 plays a crucial role in regulating metabolic rate and fuel oxidation; however, the mechanisms by which it affects whole-body energy metabolism are still not completely understood. Skeletal muscle (SKM plays a relevant role in energy metabolism and responds to thyroid state by remodeling the metabolic characteristics and cytoarchitecture of myocytes. These processes are coordinated with changes in mitochondrial content, bioenergetics, substrate oxidation rate, and oxidative phosphorylation efficiency. Recent data indicate that emerging iodothyronines have biological activity. Among these, 3,5-diiodo-L-thyronine (T2 affects energy metabolism, SKM substrate utilization, and mitochondrial functionality. The effects it exerts on SKM mitochondria involve more aspects of mitochondrial bioenergetics; among these, respiratory chain activity, mitochondrial thermogenesis, and lipid-handling are stimulated rapidly. This minireview focuses on signaling and biochemical pathways activated by T3 and T2 in SKM that influence the above processes. These novel aspects of thyroid physiology could reveal new perspectives for understanding the involvement of SKM mitochondria in hypo- and hyperthyroidism.

  20. THE EFFECTS OF AEROBIC EXERCISE ON SKELETAL MUSCLE METABOLISM, MORPHOLOGY AND IN SITU ENDURANCE IN DIABETIC RATS

    Directory of Open Access Journals (Sweden)

    Nilay Ergen

    2005-12-01

    Full Text Available The effects of aerobic exercise training on skeletal muscle endurance capacity were examined in diabetic rats in situ. Moderate diabetes was induced by iv injection of streptozotocin and an exercise training program on a treadmill was carried out for 8 weeks. The animals randomly assigned to one of the four experimental groups: control-sedentary (CS, control-exercise (CE, diabetic-sedentary (DS or diabetic-exercise (DE. The changes in the muscle endurance capacity were evaluated through the square wave impulses (supramaximal of 0.2-ms duration at 1 Hz in the in situ gastrocnemius-soleus muscle complex. Muscle was stimulated continuously until tension development reduced to the half of this maximal value. Time interval between the beginning and the end of stimulation period is defined as contraction duration. Following the training period, blood glucose level reduced significantly in the DE group compared to DS group (p < 0.05. The soles muscle citrate synthase activity was increased significantly in both of the trained groups compared to sedentary animals (p < 0.05. Fatigued muscle lactate values were not significantly different from each other. Ultrastractural abnormality of the skeletal muscle in DS group disappeared with training. Presence of increased lipid droplets, mitochondria clusters and glycogen accumulation was observed in the skeletal muscle of DE group. The contraction duration was longer in the DE group than others (p < 0.001. Fatigue resistance of exercised diabetic animals may be explained by increased intramyocellular lipid droplets, high blood glucose level and muscle citrate synthase activity

  1. Effect of endurance training on glucose transport capacity and glucose transporter expression in rat skeletal muscle

    International Nuclear Information System (INIS)

    Ploug, T.; Stallknecht, B.M.; Pedersen, O.; Kahn, B.B.; Ohkuwa, T.; Vinten, J.; Galbo, H.

    1990-01-01

    The effect of 10 wk endurance swim training on 3-O-methylglucose (3-MG) uptake (at 40 mM 3-MG) in skeletal muscle was studied in the perfused rat hindquarter. Training resulted in an increase of approximately 33% for maximum insulin-stimulated 3-MG transport in fast-twitch red fibers and an increase of approximately 33% for contraction-stimulated transport in slow-twitch red fibers compared with nonexercised sedentary muscle. A fully additive effect of insulin and contractions was observed both in trained and untrained muscle. Compared with transport in control rats subjected to an almost exhaustive single exercise session the day before experiment both maximum insulin- and contraction-stimulated transport rates were increased in all muscle types in trained rats. Accordingly, the increased glucose transport capacity in trained muscle was not due to a residual effect of the last training session. Half-times for reversal of contraction-induced glucose transport were similar in trained and untrained muscles. The concentrations of mRNA for GLUT-1 (the erythrocyte-brain-Hep G2 glucose transporter) and GLUT-4 (the adipocyte-muscle glucose transporter) were increased approximately twofold by training in fast-twitch red muscle fibers. In parallel to this, Western blot demonstrated a approximately 47% increase in GLUT-1 protein and a approximately 31% increase in GLUT-4 protein. This indicates that the increases in maximum velocity for 3-MG transport in trained muscle is due to an increased number of glucose transporters

  2. Effect of extraluminal ATP application on vascular tone and blood flow in skeletal muscle

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin; Al-Khazraji, Baraa K; Mortensen, Stefan P

    2013-01-01

    During skeletal muscle contractions, the concentration of ATP increases in muscle interstitial fluid as measured by microdialysis probes. This increase is associated with the magnitude of blood flow, suggesting that interstitial ATP may be important for contraction-induced vasodilation. However...... studied. The rat gluteus maximus skeletal muscle model was used to study changes in local skeletal muscle hemodynamics. Superfused ATP at concentrations found during muscle contractions (1-10 µM) increased blood flow by up to 400%. In this model, the underlying mechanism was also examined by inhibition...... in interstitial ATP concentrations increases muscle blood flow, indicating that the contraction-induced increase in skeletal muscle interstitial [ATP] is important for exercise hyperemia. The vasodilator effect of ATP application is mediated by NO and prostanoid formation....

  3. Repeated static contractions increase mitochondrial vulnerability toward oxidative stress in human skeletal muscle

    DEFF Research Database (Denmark)

    Sahlin, Kent; Nielsen, Jens Steen; Mogensen, Martin

    2006-01-01

    Repeated static contractions (RSC) induce large fluctuations in tissue oxygen tension and increase the generation of reactive oxygen species (ROS). This study investigated the effect of RSC on muscle contractility, mitochondrial respiratory function, and in vitro sarcoplasmic reticulum (SR) Ca(2......+) kinetics in human muscle. Ten male subjects performed five bouts of static knee extension with 10-min rest in between. Each bout of RSC (target torque 66% of maximal voluntary contraction torque) was maintained to fatigue. Muscle biopsies were taken preexercise and 0.3 and 24 h postexercise from vastus...... lateralis. Mitochondria were isolated and respiratory function measured after incubation with H(2)O(2) (HPX) or control medium (Con). Mitochondrial function was not affected by RSC during Con. However, RSC exacerbated mitochondrial dysfunction during HPX, resulting in decreased respiratory control index...

  4. Ex Vivo Gene Therapy Using Human Mesenchymal Stem Cells to Deliver Growth Factors in the Skeletal Muscle of a Familial ALS Rat Model.

    Science.gov (United States)

    Suzuki, Masatoshi; Svendsen, Clive N

    2016-01-01

    Therapeutic protein and molecule delivery to target sites by transplanted human stem cells holds great promise for ex vivo gene therapy. Our group has demonstrated the therapeutic benefits of ex vivo gene therapy targeting the skeletal muscles in a transgenic rat model of familial amyotrophic lateral sclerosis (ALS). We used human mesenchymal stem cells (hMSCs) and genetically modified them to release neuroprotective growth factors such as glial cell line-derived neurotrophic factor (GDNF) and vascular endothelial growth factor (VEGF). Intramuscular growth factor delivery via hMSCs can enhance neuromuscular innervation and motor neuron survival in a rat model of ALS (SOD1(G93A) transgenic rats). Here, we describe the protocol of ex vivo delivery of growth factors via lentiviral vector-mediated genetic modification of hMSCs and hMSC transplantation into the skeletal muscle of a familial ALS rat model.

  5. Na+-K+-ATPase in rat skeletal muscle: muscle fiber-specific differences in exercise-induced changes in ion affinity and maximal activity

    DEFF Research Database (Denmark)

    Juel, Carsten

    2008-01-01

    It is unclear whether muscle activity reduces or increases Na(+)-K(+)-ATPase maximal in vitro activity in rat skeletal muscle, and it is not known whether muscle activity changes the Na(+)-K(+)-ATPase ion affinity. The present study uses quantification of ATP hydrolysis to characterize muscle fiber...... membranes of glycolytic muscle, which abolished the fiber-type difference in Na(+) affinity. K(m) for K(+) (in the presence of Na(+)) was not influenced by running. Running only increased the maximal in vitro activity (V(max)) in total membranes from soleus, whereas V(max) remained constant in the three...... other muscles tested. In conclusion, muscle activity induces fiber type-specific changes both in Na(+) affinity and maximal in vitro activity of the Na(+)-K(+)-ATPase. The underlying mechanisms may involve translocation of subunits and increased association between PLM units and the alphabeta complex...

  6. Generation of a vascularized organoid using skeletal muscle as the inductive source.

    LENUS (Irish Health Repository)

    Messina, Aurora

    2005-09-01

    The technology required for creating an in vivo microenvironment and a neovasculature that can grow with and service new tissue is lacking, precluding the possibility of engineering complex three-dimensional organs. We have shown that when an arterio-venous (AV) loop is constructed in vivo in the rat groin, and placed inside a semisealed chamber, an extensive functional vasculature is generated. To test whether this unusually angiogenic environment supports the survival and growth of implanted tissue or cells, we inserted various preparations of rat and human skeletal muscle. We show that after 6 weeks incubation of muscle tissue, the chamber filled with predominantly well-vascularized recipient-derived adipose tissue, but some new donor-derived skeletal muscle and connective tissue were also evident. When primary cultured myoblasts were inserted into the chamber with the AV loop, they converted to mature striated muscle fibers. Furthermore, we identify novel adipogenesis-inducing properties of skeletal muscle. This represents the first report of a specific three-dimensional tissue grown on its own vascular supply.

  7. Increased reactive oxygen species production and lower abundance of complex I subunits and carnitine palmitoyltransferase 1B protein despite normal mitochondrial respiration in insulin-resistant human skeletal muscle.

    Science.gov (United States)

    Lefort, Natalie; Glancy, Brian; Bowen, Benjamin; Willis, Wayne T; Bailowitz, Zachary; De Filippis, Elena A; Brophy, Colleen; Meyer, Christian; Højlund, Kurt; Yi, Zhengping; Mandarino, Lawrence J

    2010-10-01

    The contribution of mitochondrial dysfunction to skeletal muscle insulin resistance remains elusive. Comparative proteomics are being applied to generate new hypotheses in human biology and were applied here to isolated mitochondria to identify novel changes in mitochondrial protein abundance present in insulin-resistant muscle. Mitochondria were isolated from vastus lateralis muscle from lean and insulin-sensitive individuals and from obese and insulin-resistant individuals who were otherwise healthy. Respiration and reactive oxygen species (ROS) production rates were measured in vitro. Relative abundances of proteins detected by mass spectrometry were determined using a normalized spectral abundance factor method. NADH- and FADH(2)-linked maximal respiration rates were similar between lean and obese individuals. Rates of pyruvate and palmitoyl-DL-carnitine (both including malate) ROS production were significantly higher in obesity. Mitochondria from obese individuals maintained higher (more negative) extramitochondrial ATP free energy at low metabolic flux, suggesting that stronger mitochondrial thermodynamic driving forces may underlie the higher ROS production. Tandem mass spectrometry identified protein abundance differences per mitochondrial mass in insulin resistance, including lower abundance of complex I subunits and enzymes involved in the oxidation of branched-chain amino acids (BCAA) and fatty acids (e.g., carnitine palmitoyltransferase 1B). We provide data suggesting normal oxidative capacity of mitochondria in insulin-resistant skeletal muscle in parallel with high rates of ROS production. Furthermore, we show specific abundance differences in proteins involved in fat and BCAA oxidation that might contribute to the accumulation of lipid and BCAA frequently associated with the pathogenesis of insulin resistance.

  8. Serum Is Not Necessary for Prior Pharmacological Activation of AMPK to Increase Insulin Sensitivity of Mouse Skeletal Muscle

    Directory of Open Access Journals (Sweden)

    Nicolas O. Jørgensen

    2018-04-01

    Full Text Available Exercise, contraction, and pharmacological activation of AMP-activated protein kinase (AMPK by 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR have all been shown to increase muscle insulin sensitivity for glucose uptake. Intriguingly, improvements in insulin sensitivity following contraction of isolated rat and mouse skeletal muscle and prior AICAR stimulation of isolated rat skeletal muscle seem to depend on an unknown factor present in serum. One study recently questioned this requirement of a serum factor by showing serum-independency with muscle from old rats. Whether a serum factor is necessary for prior AICAR stimulation to increase insulin sensitivity of mouse skeletal muscle is not known. Therefore, we investigated the necessity of serum for this effect of AICAR in mouse skeletal muscle. We found that the ability of prior AICAR stimulation to improve insulin sensitivity of mouse skeletal muscle did not depend on the presence of serum during AICAR stimulation. Although prior AICAR stimulation did not enhance proximal insulin signaling, insulin-stimulated phosphorylation of Tre-2/BUB2/CDC16- domain family member 4 (TBC1D4 Ser711 was greater in prior AICAR-stimulated muscle compared to all other groups. These results imply that the presence of a serum factor is not necessary for prior AMPK activation by AICAR to enhance insulin sensitivity of mouse skeletal muscle.

  9. Skeletal muscle-specific expression of PGC-1α-b, an exercise-responsive isoform, increases exercise capacity and peak oxygen uptake.

    Directory of Open Access Journals (Sweden)

    Miki Tadaishi

    Full Text Available Maximal oxygen uptake (VO(2max predicts mortality and is associated with endurance performance. Trained subjects have a high VO(2max due to a high cardiac output and high metabolic capacity of skeletal muscles. Peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α, a nuclear receptor coactivator, promotes mitochondrial biogenesis, a fiber-type switch to oxidative fibers, and angiogenesis in skeletal muscle. Because exercise training increases PGC-1α in skeletal muscle, PGC-1α-mediated changes may contribute to the improvement of exercise capacity and VO(2max. There are three isoforms of PGC-1α mRNA. PGC-1α-b protein, whose amino terminus is different from PGC-1α-a protein, is a predominant PGC-1α isoform in response to exercise. We investigated whether alterations of skeletal muscle metabolism by overexpression of PGC-1α-b in skeletal muscle, but not heart, would increase VO(2max and exercise capacity.Transgenic mice showed overexpression of PGC-1α-b protein in skeletal muscle but not in heart. Overexpression of PGC-1α-b promoted mitochondrial biogenesis 4-fold, increased the expression of fatty acid transporters, enhanced angiogenesis in skeletal muscle 1.4 to 2.7-fold, and promoted exercise capacity (expressed by maximum speed by 35% and peak oxygen uptake by 20%. Across a broad range of either the absolute exercise intensity, or the same relative exercise intensities, lipid oxidation was always higher in the transgenic mice than wild-type littermates, suggesting that lipid is the predominant fuel source for exercise in the transgenic mice. However, muscle glycogen usage during exercise was absent in the transgenic mice.Increased mitochondrial biogenesis, capillaries, and fatty acid transporters in skeletal muscles may contribute to improved exercise capacity via an increase in fatty acid utilization. Increases in PGC-1α-b protein or function might be a useful strategy for sedentary subjects to perform exercise

  10. Intermittent whole-body vibration attenuates a reduction in the number of the capillaries in unloaded rat skeletal muscle.

    Science.gov (United States)

    Kaneguchi, Akinori; Ozawa, Junya; Kawamata, Seiichi; Kurose, Tomoyuki; Yamaoka, Kaoru

    2014-09-26

    Whole-body vibration has been suggested for the prevention of muscle mass loss and muscle wasting as an attractive measure for disuse atrophy. This study examined the effects of daily intermittent whole-body vibration and weight bearing during hindlimb suspension on capillary number and muscle atrophy in rat skeletal muscles. Sixty male Wistar rats were randomly divided into four groups: control (CONT), hindlimb suspension (HS), HS + weight bearing (WB), and HS + whole-body vibration (VIB) (n = 15 each). Hindlimb suspension was applied for 2 weeks in HS, HS + WB, and HS + VIB groups. During suspension, rats in HS + VIB group were placed daily on a vibrating whole-body vibration platform for 20 min. In HS + WB group, suspension was interrupted for 20 min/day, allowing weight bearing. Untreated rats were used as controls. Soleus muscle wet weights and muscle fiber cross-sectional areas (CSA) significantly decreased in HS, HS + WB, and HS + VIB groups compared with CONT group. Both muscle weights and CSA were significantly greater in HS + WB and HS + VIB groups compared with HS group. Capillary numbers (represented by capillary-to-muscle fiber ratio) were significantly smaller in all hindlimb suspension-treated groups compared with CONT group. However, a reduction in capillary number by unloading hindlimbs was partially prevented by whole-body vibration. These findings were supported by examining mRNA for angiogenic-related factors. Expression levels of a pro-angiogenic factor, vascular endothelial growth factor-A mRNA, were significantly lower in all hindlimb suspension-treated groups compared with CONT group. There were no differences among hindlimb suspension-treated groups. Expression levels of an anti-angiogenic factor, CD36 (receptor for thrombospondin-1) mRNA, were significantly higher in all hindlimb suspension-treated groups compared with CONT group. Among the hindlimb suspension-treated groups, expression of CD

  11. Influence of experimental hyperthyroidism on skeletal muscle metabolism in the rat.

    Science.gov (United States)

    van Hardeveld, C; Kassenaar, A A

    1977-05-01

    In this study hind-limb perfusion was used to investigate the influence of thyroid hormones on some metabolic parameters in the skeletal muscle of the rat. Daily injection of 20 microng L-thyroxine (T4) per 100 g b. w. for a week caused a 25% increase in oxygen consumption. Further enlargement of the T4 dose had little additive effect. In the dose range 20--80 microng T4/100g b.w., no important changes occurred in lactate production or glucose consumption. Only at the highest T4 dose did the glucose consumption increase significantly. The most profound effect of T4 was on lipolysis. A daily dose of 20 microng T4/100 g b. w. gave a doubling of glycerol production rate, the maximum occuring at a dose of 40 microng T4/100 g b. w. Inactivation of the nervous system was without influence on the T4-induced increase in oxygen consumption. However, the T4-induced elevation of lipolysis disappeared after abolition of the nervous activity. This raises the possibility that the T4 effect on lipolysis in skeletal muscle is a potentiation of catecholamine effects. The T4-induced oxygen consumption increase might be dependent not on the lipolytic process but rather on other energy-consuming cell processes.

  12. Impaired glycogen synthase activity and mitochondrial dysfunction in skeletal muscle

    DEFF Research Database (Denmark)

    Højlund, Kurt; Beck-Nielsen, Henning

    2006-01-01

    Insulin resistance in skeletal muscle is a major hallmark of type 2 diabetes and an early detectable abnormality in the development of this disease. The cellular mechanisms of insulin resistance include impaired insulin-mediated muscle glycogen synthesis and increased intramyocellular lipid content......, whereas impaired insulin activation of muscle glycogen synthase represents a consistent, molecular defect found in both type 2 diabetic and high-risk individuals. Despite several studies of the insulin signaling pathway believed to mediate dephosphorylation and hence activation of glycogen synthase......, the molecular mechanisms responsible for this defect remain unknown. Recently, the use of phospho-specific antibodies in human diabetic muscle has revealed hyperphosphorylation of glycogen synthase at sites not regulated by the classical insulin signaling pathway. In addition, novel approaches such as gene...

  13. Activation of the skeletal alpha-actin promoter during muscle regeneration.

    Science.gov (United States)

    Marsh, D R; Carson, J A; Stewart, L N; Booth, F W

    1998-11-01

    Little is known concerning promoter regulation of genes in regenerating skeletal muscles. In young rats, recovery of muscle mass and protein content is complete within 21 days. During the initial 5-10 days of regeneration, mRNA abundance for IGF-I, myogenin and MyoD have been shown to be dramatically increased. The skeletal alpha-actin promoter contains E box and serum response element (SRE) regulatory regions which are directly or indirectly activated by myogenin (or MyoD) and IGF-I proteins, respectively. We hypothesized that the skeletal alpha-actin promoter activity would increase during muscle regeneration, and that this induction would occur before muscle protein content returned to normal. Total protein content and the percentage content of skeletal alpha-actin protein was diminished at 4 and 8 days and re-accumulation had largely occurred by 16 days post-bupivacaine injection. Skeletal alpha-actin mRNA per whole muscle was decreased at day 8, and thereafter returned to control values. During regeneration at day 8, luciferase activity (a reporter of promoter activity) directed by -424 skeletal alpha-actin and -99 skeletal alpha-actin promoter constructs was increased by 700% and 250% respectively; however, at day 16, skeletal alpha-actin promoter activities were similar to control values. Thus, initial activation of the skeletal alpha-actin promoter is associated with regeneration of skeletal muscle, despite not being sustained during the later stages of regrowth. The proximal SRE of the skeletal alpha-actin promoter was not sufficient to confer a regeneration-induced promoter activation, despite increased serum response factor protein binding to this regulatory element in electrophoretic mobility shift assays. Skeletal alpha-actin promoter induction during regeneration is due to a combination of regulatory elements, at least including the SRE and E box.

  14. Contraction-induced lipolysis is not impaired by inhibition of hormone-sensitive lipase in skeletal muscle.

    Science.gov (United States)

    Alsted, Thomas J; Ploug, Thorkil; Prats, Clara; Serup, Annette K; Høeg, Louise; Schjerling, Peter; Holm, Cecilia; Zimmermann, Robert; Fledelius, Christian; Galbo, Henrik; Kiens, Bente

    2013-10-15

    In skeletal muscle hormone-sensitive lipase (HSL) has long been accepted to be the principal enzyme responsible for lipolysis of intramyocellular triacylglycerol (IMTG) during contractions. However, this notion is based on in vitro lipase activity data, which may not reflect the in vivo lipolytic activity. We investigated lipolysis of IMTG in soleus muscles electrically stimulated to contract ex vivo during acute pharmacological inhibition of HSL in rat muscles and in muscles from HSL knockout (HSL-KO) mice. Measurements of IMTG are complicated by the presence of adipocytes located between the muscle fibres. To circumvent the problem with this contamination we analysed intramyocellular lipid droplet content histochemically. At maximal inhibition of HSL in rat muscles, contraction-induced breakdown of IMTG was identical to that seen in control muscles (P contractions IMTG staining decreased significantly in both HSL-KO and WT muscles (P skeletal muscle, other TG lipases accordingly being of negligible importance for lipolysis of IMTG. The present study is the first to demonstrate that contraction-induced lipolysis of IMTG occurs in the absence of HSL activity in rat and mouse skeletal muscle. Furthermore, the results suggest that ATGL is activated and plays a major role in lipolysis of IMTG during muscle contractions.

  15. Gestational Undernourishment Modifies the Composition of Skeletal Muscle Transverse Tubule Membranes and the Mechanical Properties of Muscles in Newborn Rats

    Directory of Open Access Journals (Sweden)

    Ricardo Tonathiu Ramírez-Oseguera

    2013-10-01

    Full Text Available Backgroud/Aims: Skeletal muscle (SM constitutes more than 40% of the body weight in adulthood. Transports dietary glucose mainly through the insulin-dependent glucose transporter (Glut-4 located in the Transverse tubule membrane system (TT. The TT development ends shortly after birth. The TT membrane hosts the proteins involved in excitation-contraction coupling and glucose uptake. Glycaemic regulation through movement is a key function of fully developed skeletal muscle. In this study, we aimed to characterize the effect of gestational undernourishment (GUN in rats GLUT-4 expression and on the protein/lipid content of the TT membranes. We also examined the effect of GUN on the mechanical properties of muscles as an indication of the metabolic condition of the SM at birth. Methods: Isolated TT membrane from SM of GUN rats were used to study lipid/protein content and protein stability by differential scanning calorimetry. The effect of GUN on the SM mechanical properties was determined in isolated Extensor Digitorum Longus (EDL muscle. Results: We demonstrate that compared to control, GUN in the new-born produces; i decreases body weight; ii diminution in SM mass; iii decreases the formation of TT membranes; iv expresses TT membrane proteins with higher thermal stability. The TT membrane expression of GLUT-4 in GUN offspring was twice that of controls. The isolated EDL of GUN offspring was 20% stronger as measured by contractile force and more resistant to fatigue relative to controls. Conclusion; These results provide the first evidence of adaptive changes of the SM in new-borns exposed to severe gestational food restriction. The effects of GUN on muscle at birth are the first step toward detrimental SM metabolic function, contributing to the physiopathology of metabolic diseases in adulthood.

  16. Gestational undernourishment modifies the composition of skeletal muscle transverse tubule membranes and the mechanical properties of muscles in newborn rats.

    Science.gov (United States)

    Ramírez-Oseguera, Ricardo Tonathiu; Jiménez-Garduño, Aura Matilde; Alvarez, Rocío; Heine, Katharina; Pinzón-Estrada, Enrique; Torres-Saldaña, Ismael; Ortega, Alicia

    2013-01-01

    [corrected] Skeletal muscle (SM) constitutes more than 40% of the body weight in adulthood. Transports dietary glucose mainly through the insulin-dependent glucose transporter (Glut-4) located in the Transverse tubule membrane system (TT). The TT development ends shortly after birth. The TT membrane hosts the proteins involved in excitation-contraction coupling and glucose uptake. Glycaemic regulation through movement is a key function of fully developed skeletal muscle. In this study, we aimed to characterize the effect of gestational undernourishment (GUN) in rats GLUT-4 expression and on the protein/lipid content of the TT membranes. We also examined the effect of GUN on the mechanical properties of muscles as an indication of the metabolic condition of the SM at birth. Isolated TT membrane from SM of GUN rats were used to study lipid/protein content and protein stability by differential scanning calorimetry. The effect of GUN on the SM mechanical properties was determined in isolated Extensor Digitorum Longus (EDL) muscle. We demonstrate that compared to control, GUN in the new-born produces; i) decreases body weight; ii) diminution in SM mass; iii) decreases the formation of TT membranes; iv) expresses TT membrane proteins with higher thermal stability. The TT membrane expression of GLUT-4 in GUN offspring was twice that of controls. The isolated EDL of GUN offspring was 20% stronger as measured by contractile force and more resistant to fatigue relative to controls. These results provide the first evidence of adaptive changes of the SM in new-borns exposed to severe gestational food restriction. The effects of GUN on muscle at birth are the first step toward detrimental SM metabolic function, contributing to the physiopathology of metabolic diseases in adulthood. © 2013 S. Karger AG, Basel

  17. Rigor force responses of permeabilized fibres from fast and slow skeletal muscles of aged rats.

    Science.gov (United States)

    Plant, D R; Lynch, G S

    2001-09-01

    1. Ageing is generally associated with a decline in skeletal muscle mass and strength and a slowing of muscle contraction, factors that impact upon the quality of life for the elderly. The mechanisms underlying this age-related muscle weakness have not been fully resolved. The purpose of the present study was to determine whether the decrease in muscle force as a consequence of age could be attributed partly to a decrease in the number of cross-bridges participating during contraction. 2. Given that the rigor force is proportional to the approximate total number of interacting sites between the actin and myosin filaments, we tested the null hypothesis that the rigor force of permeabilized muscle fibres from young and old rats would not be different. 3. Permeabilized fibres from the extensor digitorum longus (fast-twitch; EDL) and soleus (predominantly slow-twitch) muscles of young (6 months of age) and old (27 months of age) male F344 rats were activated in Ca2+-buffered solutions to determine force-pCa characteristics (where pCa = -log(10)[Ca2+]) and then in solutions lacking ATP and Ca2+ to determine rigor force levels. 4. The rigor forces for EDL and soleus muscle fibres were not different between young and old rats, indicating that the approximate total number of cross-bridges that can be formed between filaments did not decline with age. We conclude that the age-related decrease in force output is more likely attributed to a decrease in the force per cross-bridge and/or decreases in the efficiency of excitation-contraction coupling.

  18. Actovegin, a non-prohibited drug increases oxidative capacity in human skeletal muscle

    DEFF Research Database (Denmark)

    Søndergård, Stine D; Dela, Flemming; Helge, Jørn W

    2016-01-01

    Actovegin, a deproteinized haemodialysate of calf blood, is suggested to have ergogenic properties, but this potential effect has never been investigated in human skeletal muscle. To investigate this purported ergogenic effect, we measured the mitochondrial respiratory capacity in permeabilized h...

  19. Activation of AMPKα2 is not crucial for mitochondrial uncoupling-induced metabolic effects but required to maintain skeletal muscle integrity.

    Directory of Open Access Journals (Sweden)

    Mario Ost

    Full Text Available Transgenic (UCP1-TG mice with ectopic expression of UCP1 in skeletal muscle (SM show a phenotype of increased energy expenditure, improved glucose tolerance and increase substrate metabolism in SM. To investigate the potential role of skeletal muscle AMPKα2 activation in the metabolic phenotype of UCP1-TG mice we generated double transgenic (DTG mice, by crossing of UCP1-TG mice with DN-AMPKα2 mice overexpressing a dominant negative α2 subunit of AMPK in SM which resulted in an impaired AMPKα2 activity by 90±9% in SM of DTG mice. Biometric analysis of young male mice showed decreased body weight, lean and fat mass for both UCP1-TG and DTG compared to WT and DN-AMPKα2 mice. Energy intake and weight-specific total energy expenditure were increased, both in UCP1-TG and DTG mice. Moreover, glucose tolerance, insulin sensitivity and fatty acid oxidation were not altered in DTG compared to UCP1-TG. Also uncoupling induced induction and secretion of fibroblast growth factor 21 (FGF21 from SM was preserved in DTG mice. However, voluntary physical cage activity as well as ad libitum running wheel access during night uncovered a severe activity intolerance of DTG mice. Histological analysis showed a progressive degenerative morphology in SM of DTG mice which was not observed in SM of UCP1-TG mice. Moreover, ATP-depletion related cellular stress response via heat shock protein 70 was highly induced, whereas capillarization regulator VEGF was suppressed in DTG muscle. In addition, AMPKα2-mediated induction of mitophagy regulator ULK1 was suppressed in DTG mice, as well as mitochondrial respiratory capacity and content. In conclusion, we demonstrate that AMPKα2 is dispensable for SM mitochondrial uncoupling induced metabolic effects on whole body energy balance, glucose homeostasis and insulin sensitivity. But strikingly, activation of AMPKα2 seems crucial for maintaining SM function, integrity and the ability to compensate chronic metabolic stress

  20. Skeletal muscle expresses the extracellular cyclic AMP–adenosine pathway

    Science.gov (United States)

    Chiavegatti, T; Costa, V L; Araújo, M S; Godinho, R O

    2007-01-01

    Background and purpose: cAMP is a key intracellular signalling molecule that regulates multiple processes of the vertebrate skeletal muscle. We have shown that cAMP can be actively pumped out from the skeletal muscle cell. Since in other tissues, cAMP efflux had been associated with extracellular generation of adenosine, in the present study we have assessed the fate of interstitial cAMP and the existence of an extracellular cAMP-adenosine signalling pathway in skeletal muscle. Experimental approach: cAMP efflux and/or its extracellular degradation were analysed by incubating rat cultured skeletal muscle with exogenous cAMP, forskolin or isoprenaline. cAMP and its metabolites were quantified by radioassay or HPLC, respectively. Key results: Incubation of cells with exogenous cAMP was followed by interstitial accumulation of 5′-AMP and adenosine, a phenomenon inhibited by selective inhibitors of ecto-phosphodiesterase (DPSPX) and ecto-nucleotidase (AMPCP). Activation of adenylyl cyclase (AC) in cultured cells with forskolin or isoprenaline increased cAMP efflux and extracellular generation of 5′-AMP and adenosine. Extracellular cAMP-adenosine pathway was also observed after direct and receptor-dependent stimulation of AC in rat extensor muscle ex vivo. These events were attenuated by probenecid, an inhibitor of ATP binding cassette family transporters. Conclusions and implications: Our results show the existence of an extracellular biochemical cascade that converts cAMP into adenosine. The functional relevance of this extracellular signalling system may involve a feedback modulation of cellular response initiated by several G protein-coupled receptor ligands, amplifying cAMP influence to a paracrine mode, through its metabolite, adenosine. PMID:18157164

  1. Regulation of skeletal muscle mitochondrial activity by thyroid hormones: focus on the “old” triiodothyronine and the “emerging” 3,5-diiodothyronine

    OpenAIRE

    Lombardi, Assunta; Moreno, Maria; de Lange, Pieter; Iossa, Susanna; Busiello, Rosa A.; Goglia, Fernando

    2015-01-01

    3,5,3′-Triiodo-L-thyronine (T3) plays a crucial role in regulating metabolic rate and fuel oxidation; however, the mechanisms by which it affects whole-body energy metabolism are still not completely understood. Skeletal muscle (SKM) plays a relevant role in energy metabolism and responds to thyroid state by remodeling the metabolic characteristics and cytoarchitecture of myocytes. These processes are coordinated with changes in mitochondrial content, bioenergetics, substrate oxidation rate, ...

  2. Altered expression of genes involved in mitochondrial oxidative phosphorylation and insulin signaling in skeletal muscle of obese women with polycystic ovary syndrome (PCOS)

    DEFF Research Database (Denmark)

    Skov, Vibe

    be of similar importance for insulin resistance in the polycystic ovary syndrome (PCOS).   Materials and methods: Using the HG-U133 Plus 2.0 expression array from Affymetrix, we analyzed gene expression in skeletal muscle from obese women with PCOS (n=16) and age- and body mass index-matched control women (n=13...... a sum statistic and conducting a permutation test. Subsequently, we performed biological pathway analysis using Gene Set Enrichment Analysis (GSEA) and Gene Microarray Pathway Profiler (GenMAPP).   Results: Women with PCOS were characterized by fasting hyperinsulinemia and impaired insulin...... validated by quantitative real-time PCR and immunoblot analyses.   Conclusion: Our results, for the first time, provide evidence for an association between insulin resistance and impaired mitochondrial oxidative metabolism in skeletal muscle in women with PCOS. Furthermore, differential expression of genes...

  3. Subcellular localization of skeletal muscle lipid droplets and PLIN family proteins OXPAT and ADRP at rest and following contraction in rat soleus muscle.

    Science.gov (United States)

    MacPherson, Rebecca E K; Herbst, Eric A F; Reynolds, Erica J; Vandenboom, Rene; Roy, Brian D; Peters, Sandra J

    2012-01-01

    Skeletal muscle lipid droplet-associated proteins (PLINs) are thought to regulate lipolysis through protein-protein interactions on the lipid droplet surface. In adipocytes, PLIN2 [adipocyte differentiation-related protein (ADRP)] is found only on lipid droplets, while PLIN5 (OXPAT, expressed only in oxidative tissues) is found both on and off the lipid droplet and may be recruited to lipid droplet membranes when needed. Our purpose was to determine whether PLIN5 is recruited to lipid droplets with contraction and to investigate the myocellular location and colocalization of lipid droplets, PLIN2, and PLIN5. Rat solei were isolated, and following a 30-min equilibration period, they were assigned to one of two groups: 1) 30 min of resting incubation and 2) 30 min of stimulation (n = 10 each). Immunofluorescence microscopy was used to determine subcellular content, distribution, and colocalization of lipid droplets, PLIN2, and PLIN5. There was a main effect for lower lipid and PLIN2 content in stimulated compared with rested muscles (P muscles (P = 0.001, r(2) = 0.99) and linearly in stimulated muscles (slope = -0.0023 ± 0.0006, P muscles (P contraction in isolated skeletal muscle.

  4. The effects of altitude training on the AMPK-related glucose transport pathway in the red skeletal muscle of both lean and obese Zucker rats.

    Science.gov (United States)

    Chen, Yu-Ching; Lee, Shin-Da; Kuo, Cha-Hua; Ho, Low-Tone

    2011-01-01

    The skeletal muscle AMP-activated protein kinase (AMPK)-related glucose transport pathway is involved in glucose homeostasis. In this study, we examined whether obese control Zucker rats had abnormal expression of proteins in the LKB1-AMPK-AS160-GLUT4 pathway in red gastrocnemius muscle compared to that in lean (normal) control Zucker rats. We also compared the chronic training effects of exercise, hypoxia, and altitude training on this pathway in lean and obese rats. At sea level, lean and obese rats were divided into 4 groups for 6 weeks training as follows: 1) control; 2) exercise (progressive daily swimming-exercise training with comparable exercise signals between the two groups); 3) hypoxia (8 hours of daily 14% O2 exposure); and 4) exercise plus hypoxia (also called altitude training). Seven animals were used for each group. The obese rats in the control group had higher body weights, elevated fasting insulin and glucose levels, and higher baseline levels of muscle AMPK and AS160 phosphorylation compared with those of lean control rats. For obese Zucker rats in the exercise or hypoxia groups, the muscle AMPK phosphorylation level was significantly decreased compared with that of the control group. For obese Zucker rats in the altitude training group, the levels of AMPK, AS160 phosphorylation, fasting insulin, and fasting glucose were decreased concomitant with an approximate 50% increase in the muscle GLUT4 protein level compared with those of the control group. In lean rats, the altitude training efficiently lowered fasting glucose and insulin levels and increased muscle AMPK and AS160 phosphorylation as well as GLUT4 protein levels. Our results provide evidence that long-term altitude training may be a potentially effective nonpharmacological strategy for treating and preventing insulin resistance based on its effects on the skeletal muscle AMPK-AS160-GLUT4 pathway.

  5. PGC-1α-mediated branched-chain amino acid metabolism in the skeletal muscle.

    Science.gov (United States)

    Hatazawa, Yukino; Tadaishi, Miki; Nagaike, Yuta; Morita, Akihito; Ogawa, Yoshihiro; Ezaki, Osamu; Takai-Igarashi, Takako; Kitaura, Yasuyuki; Shimomura, Yoshiharu; Kamei, Yasutomi; Miura, Shinji

    2014-01-01

    Peroxisome proliferator-activated receptor (PPAR) γ coactivator 1α (PGC-1α) is a coactivator of various nuclear receptors and other transcription factors, which is involved in the regulation of energy metabolism, thermogenesis, and other biological processes that control phenotypic characteristics of various organ systems including skeletal muscle. PGC-1α in skeletal muscle is considered to be involved in contractile protein function, mitochondrial function, metabolic regulation, intracellular signaling, and transcriptional responses. Branched-chain amino acid (BCAA) metabolism mainly occurs in skeletal muscle mitochondria, and enzymes related to BCAA metabolism are increased by exercise. Using murine skeletal muscle overexpressing PGC-1α and cultured cells, we investigated whether PGC-1α stimulates BCAA metabolism by increasing the expression of enzymes involved in BCAA metabolism. Transgenic mice overexpressing PGC-1α specifically in the skeletal muscle had increased the expression of branched-chain aminotransferase (BCAT) 2, branched-chain α-keto acid dehydrogenase (BCKDH), which catabolize BCAA. The expression of BCKDH kinase (BCKDK), which phosphorylates BCKDH and suppresses its enzymatic activity, was unchanged. The amount of BCAA in the skeletal muscle was significantly decreased in the transgenic mice compared with that in the wild-type mice. The amount of glutamic acid, a metabolite of BCAA catabolism, was increased in the transgenic mice, suggesting the activation of muscle BCAA metabolism by PGC-1α. In C2C12 cells, the overexpression of PGC-1α significantly increased the expression of BCAT2 and BCKDH but not BCKDK. Thus, PGC-1α in the skeletal muscle is considered to significantly contribute to BCAA metabolism.

  6. Perturbations of NAD+ salvage systems impact mitochondrial function and energy homeostasis in mouse myoblasts and intact skeletal muscle

    DEFF Research Database (Denmark)

    Andersen, Marianne Agerholm; Dall, Morten; Jensen, Benjamin Anderschou Holbech

    2018-01-01

    Nicotinamide adenine dinucleotide (NAD+) can be synthesized by nicotinamide phosphoribosyltransferase (NAMPT). We aimed to determine the role of NAMPT for maintaining NAD+ levels, mitochondrial function, and metabolic homeostasis in skeletal muscle cells. We generated stable Nampt knockdown (sh......Nampt KD) C2C12 cells using a shRNA lentiviral approach. Moreover, we applied gene electrotransfer to express cre recombinase in tibialis anterior muscle of floxed Nampt mice. In shNampt KD C2C12 myoblasts, Nampt and NAD+ levels were reduced by 70% and 50%, respectively, and maximal respiratory capacity...... was reduced by 25%. Moreover, anaerobic glycolytic flux increased by 55% and 2-deoxyglucose uptake increased by 25% in shNampt KD cells. Treatment with the NAD+ precursor nicotinamide riboside restored NAD+ levels in shNampt cells and increased maximal respiratory capacity by 18% and 32% in control and sh...

  7. Dietary Fat Quantity and Type Induce Transcriptome-Wide Effects on Alternative Splicing of Pre-mRNA in Rat Skeletal Muscle.

    Science.gov (United States)

    Black, Adam J; Ravi, Suhana; Jefferson, Leonard S; Kimball, Scot R; Schilder, Rudolf J

    2017-09-01

    Background: Fat-enriched diets produce metabolic changes in skeletal muscle, which in turn can mediate changes in gene regulation. Objective: We examined the high-fat-diet-induced changes in skeletal muscle gene expression by characterizing variations in pre-mRNA alternative splicing. Methods: Affymetrix Exon Array analysis was performed on the transcriptome of the gastrocnemius/plantaris complex of male obesity-prone Sprague-Dawley rats fed a 10% or 60% fat (lard) diet for 2 or 8 wk. The validation of exon array results was focused on troponin T ( Tnnt3 ). Tnnt3 splice form analyses were extended in studies of rats fed 10% or 30% fat diets across 1- to 8-wk treatment periods and rats fed 10% or 45% fat diets with fat sources from lard or mono- or polyunsaturated fats for 2 wk. Nuclear magnetic resonance (NMR) was used to measure body composition. Results: Consumption of a 60% fat diet for 2 or 8 wk resulted in alternative splicing of 668 and 726 pre-mRNAs, respectively, compared with rats fed a 10% fat diet. Tnnt3 transcripts were alternatively spliced in rats fed a 60% fat diet for either 2 or 8 wk. The high-fat-diet-induced changes in Tnnt3 alternative splicing were observed in rats fed a 30% fat diet across 1- to 8-wk treatment periods. Moreover, this effect depended on fat type, because Tnnt3 alternative splicing occurred in response to 45% fat diets enriched with lard but not in response to diets enriched with mono- or polyunsaturated fatty acids. Fat mass (a proxy for obesity as measured by NMR) did not differ between groups in any study. Conclusions: Rat skeletal muscle responds to overconsumption of dietary fat by modifying gene expression through pre-mRNA alternative splicing. Variations in Tnnt3 alternative splicing occur independently of obesity and are dependent on dietary fat quantity and suggest a role for saturated fatty acids in the high-fat-diet-induced modifications in Tnnt3 alternative splicing. © 2017 American Society for Nutrition.

  8. 18F-fluorodeoxyglucose and PET/CT for noninvasive study of exercise-induced glucose uptake in rat skeletal muscle and tendon

    International Nuclear Information System (INIS)

    Skovgaard, Dorthe; Kjaer, Michael; El-Ali, Henrik; Kjaer, Andreas

    2009-01-01

    To investigate exercise-related glucose uptake in rat muscle and tendon using PET/CT and to study possible explanatory changes in gene expression for the glucose transporters (GLUT1 and GLUT4). The sciatic nerve in eight Wistar rats was subjected to electrostimulation to cause unilateral isometric contractions of the calf muscle. 18 F-Fluorodeoxyglucose was administered and a PET/CT scan of the hindlimbs was performed. SUVs were calculated in both Achilles tendons and the triceps surae muscles. To exclude a spill-over effect the tendons and muscles from an ex vivo group of eight rats were cut out and scanned separately (distance≥1 cm). Muscle contractions increased glucose uptake approximately sevenfold in muscles (p<0.001) and 36% in tendons (p<0.01). The ex vivo group confirmed the increase in glucose uptake in intact animals. GLUT1 and GLUT4 were expressed in both skeletal muscle and tendon, but no changes in mRNA levels could be detected. PET/CT can be used for studying glucose uptake in rat muscle and tendon in relation to muscle contractions; however, the increased uptake of glucose was not explained by changes in gene expression of GLUT1 and GLUT4. (orig.)

  9. Differential regulation of PGC-1α expression in rat liver and skeletal muscle in response to voluntary running

    Directory of Open Access Journals (Sweden)

    Azhar Salman

    2010-04-01

    Full Text Available Abstract Background The beneficial actions of exercise training on lipid, glucose and energy metabolism and insulin sensitivity appear to be in part mediated by PGC-1α. Previous studies have shown that spontaneously exercised rats show at rest enhanced responsiveness to exogenous insulin, lower plasma insulin levels and increased skeletal muscle insulin sensitivity. This study was initiated to examine the functional interaction between exercise-induced modulation of skeletal muscle and liver PGC-1α protein expression, whole body insulin sensitivity, and circulating FFA levels as a measure of whole body fatty acid (lipid metabolism. Methods Two groups of male Wistar rats (2 Mo of age, 188.82 ± 2.77 g BW were used in this study. One group consisted of control rats placed in standard laboratory cages. Exercising rats were housed individually in cages equipped with running wheels and allowed to run at their own pace for 5 weeks. At the end of exercise training, insulin sensitivity was evaluated by comparing steady-state plasma glucose (SSPG concentrations at constant plasma insulin levels attained during the continuous infusion of glucose and insulin to each experimental group. Subsequently, soleus and plantaris muscle and liver samples were collected and quantified for PGC-1α protein expression by Western blotting. Collected blood samples were analyzed for glucose, insulin and FFA concentrations. Results Rats housed in the exercise wheel cages demonstrated almost linear increases in running activity with advancing time reaching to maximum value around 4 weeks. On an average, the rats ran a mean (Mean ± SE of 4.102 ± 0.747 km/day and consumed significantly more food as compared to sedentary controls (P P P P Conclusion These data suggest that PGC-1α most likely plays a restricted role in exercise-mediated improvements in insulin resistance (sensitivity and lowering of circulating FFA levels.

  10. Cloning and tissue distribution of rat hear fatty acid binding protein mRNA: identical forms in heart and skeletal muscle

    International Nuclear Information System (INIS)

    Claffey, K.P.; Herrera, V.L.; Brecher, P.; Ruiz-Opazo, N.

    1987-01-01

    A fatty acid binding protein (FABP) as been identified and characterized in rat heart, but the function and regulation of this protein are unclear. In this study the cDNA for rat heart FABP was cloned from a λ gt11 library. Sequencing of the cDNA showed an open reading frame coding for a protein with 133 amino acids and a calculated size of 14,776 daltons. Several differences were found between the sequence determined from the cDNA and that reported previously by protein sequencing techniques. Northern blot analysis using rat heart FABP cDNA as a probe established the presence of an abundant mRNA in rat heart about 0.85 kilobases in length. This mRNA was detected, but was not abundant, in fetal heart tissue. Tissue distribution studies showed a similar mRNA species in red, but not white, skeletal muscle. In general, the mRNA tissue distribution was similar to that of the protein detected by Western immunoblot analysis, suggesting that heart FABP expression may be regulated at the transcriptional level. S1 nuclease mapping studies confirmed that the mRNA hybridized to rat heart FABP cDNA was identical in heart and red skeletal muscle throughout the entire open reading frame. The structural differences between heart FABP and other members of this multigene family may be related to the functional requirements of oxidative muscle for fatty acids as a fuel source

  11. Cloning and tissue distribution of rat hear fatty acid binding protein mRNA: identical forms in heart and skeletal muscle

    Energy Technology Data Exchange (ETDEWEB)

    Claffey, K.P.; Herrera, V.L.; Brecher, P.; Ruiz-Opazo, N.

    1987-12-01

    A fatty acid binding protein (FABP) as been identified and characterized in rat heart, but the function and regulation of this protein are unclear. In this study the cDNA for rat heart FABP was cloned from a lambda gt11 library. Sequencing of the cDNA showed an open reading frame coding for a protein with 133 amino acids and a calculated size of 14,776 daltons. Several differences were found between the sequence determined from the cDNA and that reported previously by protein sequencing techniques. Northern blot analysis using rat heart FABP cDNA as a probe established the presence of an abundant mRNA in rat heart about 0.85 kilobases in length. This mRNA was detected, but was not abundant, in fetal heart tissue. Tissue distribution studies showed a similar mRNA species in red, but not white, skeletal muscle. In general, the mRNA tissue distribution was similar to that of the protein detected by Western immunoblot analysis, suggesting that heart FABP expression may be regulated at the transcriptional level. S1 nuclease mapping studies confirmed that the mRNA hybridized to rat heart FABP cDNA was identical in heart and red skeletal muscle throughout the entire open reading frame. The structural differences between heart FABP and other members of this multigene family may be related to the functional requirements of oxidative muscle for fatty acids as a fuel source.

  12. Physical fitness and mitochondrial respiratory capacity in horse skeletal muscle.

    Directory of Open Access Journals (Sweden)

    Dominique-Marie Votion

    Full Text Available BACKGROUND: Within the animal kingdom, horses are among the most powerful aerobic athletic mammals. Determination of muscle respiratory capacity and control improves our knowledge of mitochondrial physiology in horses and high aerobic performance in general. METHODOLOGY/PRINCIPAL FINDINGS: We applied high-resolution respirometry and multiple substrate-uncoupler-inhibitor titration protocols to study mitochondrial physiology in small (1.0-2.5 mg permeabilized muscle fibres sampled from triceps brachii of healthy horses. Oxidative phosphorylation (OXPHOS capacity (pmol O(2 • s(-1 • mg(-1 wet weight with combined Complex I and II (CI+II substrate supply (malate+glutamate+succinate increased from 77 ± 18 in overweight horses to 103 ± 18, 122 ± 15, and 129 ± 12 in untrained, trained and competitive horses (N = 3, 8, 16, and 5, respectively. Similar to human muscle mitochondria, equine OXPHOS capacity was limited by the phosphorylation system to 0.85 ± 0.10 (N = 32 of electron transfer capacity, independent of fitness level. In 15 trained horses, OXPHOS capacity increased from 119 ± 12 to 134 ± 37 when pyruvate was included in the CI+II substrate cocktail. Relative to this maximum OXPHOS capacity, Complex I (CI-linked OXPHOS capacities were only 50% with glutamate+malate, 64% with pyruvate+malate, and 68% with pyruvate+malate+glutamate, and ~78% with CII-linked succinate+rotenone. OXPHOS capacity with glutamate+malate increased with fitness relative to CI+II-supported ETS capacity from a flux control ratio of 0.38 to 0.40, 0.41 and 0.46 in overweight to competitive horses, whereas the CII/CI+II substrate control ratio remained constant at 0.70. Therefore, the apparent deficit of the CI- over CII-linked pathway capacity was reduced with physical fitness. CONCLUSIONS/SIGNIFICANCE: The scope of mitochondrial density-dependent OXPHOS capacity and the density-independent (qualitative increase of CI-linked respiratory capacity with increased

  13. Muscle and liver glycogen, protein, and triglyceride in the rat

    DEFF Research Database (Denmark)

    Richter, Erik; Sonne, Bente; Joensen Mikines, Kari

    1984-01-01

    in skeletal muscle was accompanied by increased breakdown of triglyceride and/or protein. Thus, the effect of exhausting swimming and of running on concentrations of glycogen, protein, and triglyceride in skeletal muscle and liver were studied in rats with and without deficiencies of the sympatho......-adrenal system. In control rats, both swimming and running decreased the concentration of glycogen in fast-twitch red and slow-twitch red muscle whereas concentrations of protein and triglyceride did not decrease. In the liver, swimming depleted glycogen stores but protein and triglyceride concentrations did...... not decrease. In exercising rats, muscle glycogen breakdown was impaired by adrenodemedullation and restored by infusion of epinephrine. However, impaired glycogen breakdown during exercise was not accompanied by a significant net breakdown of protein or triglyceride. Surgical sympathectomy of the muscles did...

  14. Contraction-induced skeletal muscle FAT/CD36 trafficking and FA uptake is AMPK independent

    Science.gov (United States)

    Jeppesen, J.; Albers, P. H.; Rose, A. J.; Birk, J. B.; Schjerling, P.; Dzamko, N.; Steinberg, G. R.; Kiens, B.

    2011-01-01

    The aim of this study was to investigate the molecular mechanisms regulating FA translocase CD36 (FAT/CD36) translocation and FA uptake in skeletal muscle during contractions. In one model, wild-type (WT) and AMP-dependent protein kinase kinase dead (AMPK KD) mice were exercised or extensor digitorum longus (EDL) and soleus (SOL) muscles were contracted, ex vivo. In separate studies, FAT/CD36 translocation and FA uptake in response to muscle contractions were investigated in the perfused rat hindlimb. Exercise induced a similar increase in skeletal muscle cell surface membrane FAT/CD36 content in WT (+34%) and AMPK KD (+37%) mice. In contrast, 5-aminoimidazole-4-carboxamide ribonucleoside only induced an increase in cell surface FAT/CD36 content in WT (+29%) mice. Furthermore, in the perfused rat hindlimb, muscle contraction induced a rapid (1 min, +15%) and sustained (10 min, +24%) FAT/CD36 relocation to cell surface membranes. The increase in cell surface FAT/CD36 protein content with muscle contractions was associated with increased FA uptake, both in EDL and SOL muscle from WT and AMPK KD mice and in the perfused rat hindlimb. This suggests that AMPK is not essential in regulation of FAT/CD36 translocation and FA uptake in skeletal muscle during contractions. However, AMPK could be important in regulation of FAT/CD36 distribution in other physiological situations. PMID:21297178

  15. BGP-15 Protects against Oxaliplatin-Induced Skeletal Myopathy and Mitochondrial Reactive Oxygen Species Production in Mice.

    Science.gov (United States)

    Sorensen, James C; Petersen, Aaron C; Timpani, Cara A; Campelj, Dean G; Cook, Jordan; Trewin, Adam J; Stojanovska, Vanesa; Stewart, Mathew; Hayes, Alan; Rybalka, Emma

    2017-01-01

    Chemotherapy is a leading intervention against cancer. Albeit highly effective, chemotherapy has a multitude of deleterious side-effects including skeletal muscle wasting and fatigue, which considerably reduces patient quality of life and survivability. As such, a defense against chemotherapy-induced skeletal muscle dysfunction is required. Here we investigate the effects of oxaliplatin (OXA) treatment in mice on the skeletal muscle and mitochondria, and the capacity for the Poly ADP-ribose polymerase (PARP) inhibitor, BGP-15, to ameliorate any pathological side-effects induced by OXA. To do so, we investigated the effects of 2 weeks of OXA (3 mg/kg) treatment with and without BGP-15 (15 mg/kg). OXA induced a 15% ( p lean tissue mass without significant changes in food consumption or energy expenditure. OXA treatment also altered the muscle architecture, increasing collagen deposition, neutral lipid and Ca 2+ accumulation; all of which were ameliorated with BGP-15 adjunct therapy. Here, we are the first to show that OXA penetrates the mitochondria, and, as a possible consequence of this, increases mtROS production. These data correspond with reduced diameter of isolated FDB fibers and shift in the fiber size distribution frequency of TA to the left. There was a tendency for reduction in intramuscular protein content, albeit apparently not via Murf1 (atrophy)- or p62 (autophagy)- dependent pathways. BGP-15 adjunct therapy protected against increased ROS production and improved mitochondrial viability 4-fold and preserved fiber diameter and number. Our study highlights BGP-15 as a potential adjunct therapy to address chemotherapy-induced skeletal muscle and mitochondrial pathology.

  16. The Promotion of a Functional Fibrosis in Skeletal Muscle with Volumetric Muscle Loss Injury Following the Transplantation of Muscle-ECM

    Science.gov (United States)

    2013-02-04

    Zou K, Boppart MD. Eccentric exercise facil- itates mesenchymal stem cell appearance in skeletal muscle. PLoS One 2012; 7:e29760. [40] Matziolis G...remaining muscle mass leading to additional improvements in functional capacity; how- ever, no study has explicitly studied these effects . The purpose of...muscles were isolated from donor Lewis rats. The tendon and fascia were removed and TA muscle decellularization was performed using an enzymatic and

  17. Bone marrow mesenchymal cells improve muscle function in a skeletal muscle re-injury model.

    Directory of Open Access Journals (Sweden)

    Bruno M Andrade

    Full Text Available Skeletal muscle injury is the most common problem in orthopedic and sports medicine, and severe injury leads to fibrosis and muscle dysfunction. Conventional treatment for successive muscle injury is currently controversial, although new therapies, like cell therapy, seem to be promise. We developed a model of successive injuries in rat to evaluate the therapeutic potential of bone marrow mesenchymal cells (BMMC injected directly into the injured muscle. Functional and histological assays were performed 14 and 28 days after the injury protocol by isometric tension recording and picrosirius/Hematoxilin & Eosin staining, respectively. We also evaluated the presence and the fate of BMMC on treated muscles; and muscle fiber regeneration. BMMC treatment increased maximal skeletal muscle contraction 14 and 28 days after muscle injury compared to non-treated group (4.5 ± 1.7 vs 2.5 ± 0.98 N/cm2, p<0.05 and 8.4 ± 2.3 vs. 5.7 ± 1.3 N/cm2, p<0.05 respectively. Furthermore, BMMC treatment increased muscle fiber cross-sectional area and the presence of mature muscle fiber 28 days after muscle injury. However, there was no difference in collagen deposition between groups. Immunoassays for cytoskeleton markers of skeletal and smooth muscle cells revealed an apparent integration of the BMMC within the muscle. These data suggest that BMMC transplantation accelerates and improves muscle function recovery in our extensive muscle re-injury model.

  18. Maternal obesity reduces oxidative capacity in fetal skeletal muscle of Japanese macaques

    Science.gov (United States)

    McCurdy, Carrie E.; Hetrick, Byron; Houck, Julie; Drew, Brian G.; Kaye, Spencer; Lashbrook, Melanie; Bergman, Bryan C.; Takahashi, Diana L.; Dean, Tyler A.; Gertsman, Ilya; Hansen, Kirk C.; Philp, Andrew; Hevener, Andrea L.; Chicco, Adam J.; Aagaard, Kjersti M.; Grove, Kevin L.; Friedman, Jacob E.

    2016-01-01

    Maternal obesity is proposed to alter the programming of metabolic systems in the offspring, increasing the risk for developing metabolic diseases; however, the cellular mechanisms remain poorly understood. Here, we used a nonhuman primate model to examine the impact of a maternal Western-style diet (WSD) alone, or in combination with obesity (Ob/WSD), on fetal skeletal muscle metabolism studied in the early third trimester. We find that fetal muscle responds to Ob/WSD by upregulating fatty acid metabolism, mitochondrial complex activity, and metabolic switches (CPT-1, PDK4) that promote lipid utilization over glucose oxidation. Ob/WSD fetuses also had reduced mitochondrial content, diminished oxidative capacity, and lower mitochondrial efficiency in muscle. The decrease in oxidative capacity and glucose metabolism was persistent in primary myotubes from Ob/WSD fetuses despite no additional lipid-induced stress. Switching obese mothers to a healthy diet prior to pregnancy did not improve fetal muscle mitochondrial function. Lastly, while maternal WSD alone led only to intermediary changes in fetal muscle metabolism, it was sufficient to increase oxidative damage and cellular stress. Our findings suggest that maternal obesity or WSD, alone or in combination, leads to programmed decreases in oxidative metabolism in offspring muscle. These alterations may have important implications for future health. PMID:27734025

  19. The 1-Week and 8-Month Effects of a Ketogenic Diet or Ketone Salt Supplementation on Multi-Organ Markers of Oxidative Stress and Mitochondrial Function in Rats

    Science.gov (United States)

    Kephart, Wesley C.; Mumford, Petey W.; Mao, Xuansong; Romero, Matthew A.; Hyatt, Hayden W.; Zhang, Yufeng; Mobley, Christopher B.; Quindry, John C.; Young, Kaelin C.; Beck, Darren T.; McCullough, Danielle J.; D’Agostino, Dominic P.; Lowery, Ryan P.; Wilson, Jacob M.; Kavazis, Andreas N.; Roberts, Michael D.

    2017-01-01

    We determined the short- and long-term effects of a ketogenic diet (KD) or ketone salt (KS) supplementation on multi-organ oxidative stress and mitochondrial markers. For short-term feedings, 4 month-old male rats were provided isocaloric amounts of KD (n = 10), standard chow (SC) (n = 10) or SC + KS (~1.2 g/day, n = 10). For long-term feedings, 4 month-old male rats were provided KD (n = 8), SC (n = 7) or SC + KS (n = 7) for 8 months and rotarod tested every 2 months. Blood, brain (whole cortex), liver and gastrocnemius muscle were harvested from all rats for biochemical analyses. Additionally, mitochondria from the brain, muscle and liver tissue of long-term-fed rats were analyzed for mitochondrial quantity (maximal citrate synthase activity), quality (state 3 and 4 respiration) and reactive oxygen species (ROS) assays. Liver antioxidant capacity trended higher in short-term KD- and SC + KS-fed versus SC-fed rats, and short-term KD-fed rats exhibited significantly greater serum ketones compared to SC + KS-fed rats indicating that the diet (not KS supplementation) induced ketonemia. In long term-fed rats: (a) serum ketones were significantly greater in KD- versus SC- and SC + KS-fed rats; (b) liver antioxidant capacity and glutathione peroxidase protein was significantly greater in KD- versus SC-fed rats, respectively, while liver protein carbonyls were lowest in KD-fed rats; and (c) gastrocnemius mitochondrial ROS production was significantly greater in KD-fed rats versus other groups, and this paralleled lower mitochondrial glutathione levels. Additionally, the gastrocnemius pyruvate-malate mitochondrial respiratory control ratio was significantly impaired in long-term KD-fed rats, and gastrocnemius mitochondrial quantity was lowest in these animals. Rotarod performance was greatest in KD-fed rats versus all other groups at 2, 4 and 8 months, although there was a significant age-related decline in performance existed in KD-fed rats which was not evident in the

  20. Effects of hyperbaric oxygen at 1.25 atmospheres absolute with normal air on macrophage number and infiltration during rat skeletal muscle regeneration.

    Directory of Open Access Journals (Sweden)

    Naoto Fujita

    Full Text Available Use of mild hyperbaric oxygen less than 2 atmospheres absolute (2026.54 hPa with normal air is emerging as a common complementary treatment for severe muscle injury. Although hyperbaric oxygen at over 2 atmospheres absolute with 100% O2 promotes healing of skeletal muscle injury, it is not clear whether mild hyperbaric oxygen is equally effective. The purpose of the present study was to investigate the impact of hyperbaric oxygen at 1.25 atmospheres absolute (1266.59 hPa with normal air on muscle regeneration. The tibialis anterior muscle of male Wistar rats was injured by injection of bupivacaine hydrochloride, and rats were randomly assigned to a hyperbaric oxygen experimental group or to a non-hyperbaric oxygen control group. Immediately after the injection, rats were exposed to hyperbaric oxygen, and the treatment was continued for 28 days. The cross-sectional area of centrally nucleated muscle fibers was significantly larger in rats exposed to hyperbaric oxygen than in controls 5 and 7 days after injury. The number of CD68- or CD68- and CD206-positive cells was significantly higher in rats exposed to hyperbaric oxygen than in controls 24 h after injury. Additionally, tumor necrosis factor-α and interleukin-10 mRNA expression levels were significantly higher in rats exposed to hyperbaric oxygen than in controls 24 h after injury. The number of Pax7- and MyoD- or MyoD- and myogenin-positive nuclei per mm2 and the expression levels of these proteins were significantly higher in rats exposed to hyperbaric oxygen than in controls 5 days after injury. These results suggest that mild hyperbaric oxygen promotes skeletal muscle regeneration in the early phase after injury, possibly due to reduced hypoxic conditions leading to accelerated macrophage infiltration and phenotype transition. In conclusion, mild hyperbaric oxygen less than 2 atmospheres absolute with normal air is an appropriate support therapy for severe muscle injuries.

  1. Role and metabolism of free leucine in skeletal muscle in protein sparing action of dietary carbohydrate and fat

    International Nuclear Information System (INIS)

    Nakano, Kiwao; Ishikawa, Tamotsu

    1977-01-01

    Feeding rats with either a carbohydrate meal or a fat meal to the previously fasted rats caused significant decrease in urinary output of urea and total nitrogen. The content of free leucine in skeletal muscle decreased in the rats fed either a carbohydrate meal or a fat meal. Feeding of either a carbohydrate meal or a fat meal stimulated incorporation of L-leucine-1- 14 C into protein fraction of skeletal muscle and reduced its oxidation to 14 CO 2 . These results suggest that the metabolism of leucine is under nutritional regulation and that the decrease in content of free leucine in skeletal muscle might be caused by enhanced reutilization of leucine into protein by the feeding of a carbohydrate meal or a fat meal. The role of free leucine in skeletal muscle as a regulator of protein turnover in the tissue are discussed in relation to the metabolism of this branched chain amino acid. (auth.)

  2. Imaging of human sodium-iodide symporter gene expression mediated by recombinant adenovirus in skeletal muscle of living rats

    International Nuclear Information System (INIS)

    Yang, Hyun Suk; Park, Seong-Wook; Lee, Heuiran; Kim, Sung Jin; Lee, Won Woo; Yang, You-Jung; Moon, Dae Hyuk

    2004-01-01

    We evaluated the feasibility of non-invasive imaging of recombinant adenovirus-mediated human sodium-iodide symporter (hNIS) gene expression by 99m TcO 4 - scintigraphy in skeletal muscle of rats. Replication-defective recombinant adenovirus encoding hNIS gene [Rad-CMV-hNIS 5 x 10 7 , 2 x 10 8 or 1 x 10 9 plaque forming units (pfu)] or β-galactosidase gene (Rad-CMV-LacZ 1 x 10 9 pfu) was injected into the right biceps femoris muscle of rats (n=5-6 for each group). Three days after gene transfer, scintigraphy was performed using a gamma camera 30 min after injection of 99m TcO 4 - (1.85 MBq). An additional two rats injected with 1 x 10 9 pfu of Rad-CMV-hNIS underwent 99m TcO 4 - scintigraphy with sodium perchlorate. After the imaging studies, rats were sacrificed for assessment of the biodistribution of 99m TcO 4 - and measurement of hNIS mRNA expression. In all the rats injected with 1 x 10 9 pfu of Rad-CMV-hNIS, hNIS expression was successfully imaged by 99m TcO 4 - scintigraphy, while rats injected with Rad-CMV-LacZ or lower doses of Rad-CMV-hNIS failed to show uptake. The biodistribution studies indicated that a significantly different amount of 99m TcO 4 - was retained in the liver (p 9 pfu of Rad-CMV-hNIS. The muscular hNIS mRNA level quantified by real-time reverse transcription-polymerase chain reaction was significantly higher in rats injected with 1 x 10 9 pfu of Rad-CMV-hNIS (p 9 pfu of Rad-CMV-hNIS were specifically inhibited by sodium perchlorate. This study illustrated that 99m TcO 4 - scintigraphy can monitor Rad-CMV-hNIS-mediated gene expression in skeletal muscle of rats, non-invasively and quantitatively. (orig.)

  3. The proteomic signature of insulin-resistant human skeletal muscle reveals increased glycolytic and decreased mitochondrial enzymes

    DEFF Research Database (Denmark)

    Giebelstein, J; Poschmann, G; Højlund, K

    2012-01-01

    The molecular mechanisms underlying insulin resistance in skeletal muscle are incompletely understood. Here, we aimed to obtain a global picture of changes in protein abundance in skeletal muscle in obesity and type 2 diabetes, and those associated with whole-body measures of insulin action....

  4. in Skeletal Muscle

    Directory of Open Access Journals (Sweden)

    Espen E. Spangenburg

    2011-01-01

    Full Text Available Triglyceride storage is altered across various chronic health conditions necessitating various techniques to visualize and quantify lipid droplets (LDs. Here, we describe the utilization of the BODIPY (493/503 dye in skeletal muscle as a means to analyze LDs. We found that the dye was a convenient and simple approach to visualize LDs in both sectioned skeletal muscle and cultured adult single fibers. Furthermore, the dye was effective in both fixed and nonfixed cells, and the staining seemed unaffected by permeabilization. We believe that the use of the BODIPY (493/503 dye is an acceptable alternative and, under certain conditions, a simpler method for visualizing LDs stored within skeletal muscle.

  5. Effects of high-intensity swimming training on GLUT-4 and glucose transport activity in rat skeletal muscle.

    Science.gov (United States)

    Terada, S; Yokozeki, T; Kawanaka, K; Ogawa, K; Higuchi, M; Ezaki, O; Tabata, I

    2001-06-01

    This study was performed to assess the effects of short-term, extremely high-intensity intermittent exercise training on the GLUT-4 content of rat skeletal muscle. Three- to four-week-old male Sprague-Dawley rats with an initial body weight ranging from 45 to 55 g were used for this study. These rats were randomly assigned to an 8-day period of high-intensity intermittent exercise training (HIT), relatively high-intensity intermittent prolonged exercise training (RHT), or low-intensity prolonged exercise training (LIT). Age-matched sedentary rats were used as a control. In the HIT group, the rats repeated fourteen 20-s swimming bouts with a weight equivalent to 14, 15, and 16% of body weight for the first 2, the next 4, and the last 2 days, respectively. Between exercise bouts, a 10-s pause was allowed. RHT consisted of five 17-min swimming bouts with a 3-min rest between bouts. During the first bout, the rat swam without weight, whereas during the following four bouts, the rat was attached to a weight equivalent to 4 and 5% of its body weight for the first 5 days and the following 3 days, respectively. Rats in the LIT group swam 6 h/day for 8 days in two 3-h bouts separated by 45 min of rest. In the first experiment, the HIT, LIT, and control rats were compared. GLUT-4 content in the epitrochlearis muscle in the HIT and LIT groups after training was significantly higher than that in the control rats by 83 and 91%, respectively. Furthermore, glucose transport activity, stimulated maximally by both insulin (2 mU/ml) (HIT: 48%, LIT: 75%) and contractions (25 10-s tetani) (HIT: 55%, LIT: 69%), was higher in the training groups than in the control rats. However, no significant differences in GLUT-4 content or in maximal glucose transport activity in response to both insulin and contractions were observed between the two training groups. The second experiment demonstrated that GLUT-4 content after HIT did not differ from that after RHT (66% higher in trained rats than

  6. Atomoxetine Prevents Dexamethasone-Induced Skeletal Muscle Atrophy in Mice

    Science.gov (United States)

    Jesinkey, Sean R.; Korrapati, Midhun C.; Rasbach, Kyle A.; Beeson, Craig C.

    2014-01-01

    Skeletal muscle atrophy remains a clinical problem in numerous pathologic conditions. β2-Adrenergic receptor agonists, such as formoterol, can induce mitochondrial biogenesis (MB) to prevent such atrophy. Additionally, atomoxetine, an FDA-approved norepinephrine reuptake inhibitor, was positive in a cellular assay for MB. We used a mouse model of dexamethasone-induced skeletal muscle atrophy to investigate the potential role of atomoxetine and formoterol to prevent muscle mass loss. Mice were administered dexamethasone once daily in the presence or absence of formoterol (0.3 mg/kg), atomoxetine (0.1 mg/kg), or sterile saline. Animals were euthanized at 8, 16, and 24 hours or 8 days later. Gastrocnemius muscle weights, changes in mRNA and protein expression of peroxisome proliferator–activated receptor-γ coactivator-1 α (PGC-1α) isoforms, ATP synthase β, cytochrome c oxidase subunit I, NADH dehydrogenase (ubiquinone) 1 β subcomplex, 8, ND1, insulin-like growth factor 1 (IGF-1), myostatin, muscle Ring-finger protein-1 (muscle atrophy), phosphorylated forkhead box protein O 3a (p-FoxO3a), Akt, mammalian target of rapamycin (mTOR), and ribosomal protein S6 (rp-S6; muscle hypertrophy) in naive and muscle-atrophied mice were measured. Atomoxetine increased p-mTOR 24 hours after treatment in naïve mice, but did not change any other biomarkers. Formoterol robustly activated the PGC-1α-4-IGF1–Akt-mTOR-rp-S6 pathway and increased p-FoxO3a as early as 8 hours and repressed myostatin at 16 hours. In contrast to what was observed with acute treatment, chronic treatment (7 days) with atomoxetine increased p-Akt and p-FoxO3a, and sustained PGC-1α expression and skeletal muscle mass in dexamethasone-treated mice, in a manner comparable to formoterol. In conclusion, chronic treatment with a low dose of atomoxetine prevented dexamethasone-induced skeletal muscle wasting and supports a potential role in preventing muscle atrophy. PMID:25292181

  7. PGC-1α-mediated branched-chain amino acid metabolism in the skeletal muscle.

    Directory of Open Access Journals (Sweden)

    Yukino Hatazawa

    Full Text Available Peroxisome proliferator-activated receptor (PPAR γ coactivator 1α (PGC-1α is a coactivator of various nuclear receptors and other transcription factors, which is involved in the regulation of energy metabolism, thermogenesis, and other biological processes that control phenotypic characteristics of various organ systems including skeletal muscle. PGC-1α in skeletal muscle is considered to be involved in contractile protein function, mitochondrial function, metabolic regulation, intracellular signaling, and transcriptional responses. Branched-chain amino acid (BCAA metabolism mainly occurs in skeletal muscle mitochondria, and enzymes related to BCAA metabolism are increased by exercise. Using murine skeletal muscle overexpressing PGC-1α and cultured cells, we investigated whether PGC-1α stimulates BCAA metabolism by increasing the expression of enzymes involved in BCAA metabolism. Transgenic mice overexpressing PGC-1α specifically in the skeletal muscle had increased the expression of branched-chain aminotransferase (BCAT 2, branched-chain α-keto acid dehydrogenase (BCKDH, which catabolize BCAA. The expression of BCKDH kinase (BCKDK, which phosphorylates BCKDH and suppresses its enzymatic activity, was unchanged. The amount of BCAA in the skeletal muscle was significantly decreased in the transgenic mice compared with that in the wild-type mice. The amount of glutamic acid, a metabolite of BCAA catabolism, was increased in the transgenic mice, suggesting the activation of muscle BCAA metabolism by PGC-1α. In C2C12 cells, the overexpression of PGC-1α significantly increased the expression of BCAT2 and BCKDH but not BCKDK. Thus, PGC-1α in the skeletal muscle is considered to significantly contribute to BCAA metabolism.

  8. The exercised skeletal muscle: a review

    Directory of Open Access Journals (Sweden)

    Marina Marini

    2010-09-01

    Full Text Available The skeletal muscle is the second more plastic tissue of the body - second to the nervous tissue only. In fact, both physical activity and inactivity contribute to modify the skeletal muscle, by continuous signaling through nerve impulses, mechanical stimuli and humoral clues. In turn, the skeletal muscle sends signals to the body, thus contributing to its homeostasis. We'll review here the contribute of physical exercise to the shaping of skeletal muscle, to the adaptation of its mass and function to the different needs imposed by different physical activities and to the attainment of the health benefits associated with active skeletal muscles. Focus will primarily be on the molecular pathways and on gene regulation that result in skeletal muscle adaptation to exercise.

  9. Length dependence of force generation exhibit similarities between rat cardiac myocytes and skeletal muscle fibres.

    Science.gov (United States)

    Hanft, Laurin M; McDonald, Kerry S

    2010-08-01

    According to the Frank-Starling relationship, increased ventricular volume increases cardiac output, which helps match cardiac output to peripheral circulatory demand. The cellular basis for this relationship is in large part the myofilament length-tension relationship. Length-tension relationships in maximally calcium activated preparations are relatively shallow and similar between cardiac myocytes and skeletal muscle fibres. During twitch activations length-tension relationships become steeper in both cardiac and skeletal muscle; however, it remains unclear whether length dependence of tension differs between striated muscle cell types during submaximal activations. The purpose of this study was to compare sarcomere length-tension relationships and the sarcomere length dependence of force development between rat skinned left ventricular cardiac myocytes and fast-twitch and slow-twitch skeletal muscle fibres. Muscle cell preparations were calcium activated to yield 50% maximal force, after which isometric force and rate constants (k(tr)) of force development were measured over a range of sarcomere lengths. Myofilament length-tension relationships were considerably steeper in fast-twitch fibres compared to slow-twitch fibres. Interestingly, cardiac myocyte preparations exhibited two populations of length-tension relationships, one steeper than fast-twitch fibres and the other similar to slow-twitch fibres. Moreover, myocytes with shallow length-tension relationships were converted to steeper length-tension relationships by protein kinase A (PKA)-induced myofilament phosphorylation. Sarcomere length-k(tr) relationships were distinct between all three cell types and exhibited patterns markedly different from Ca(2+) activation-dependent k(tr) relationships. Overall, these findings indicate cardiac myocytes exhibit varied length-tension relationships and sarcomere length appears a dominant modulator of force development rates. Importantly, cardiac myocyte length

  10. Comparison of Mitochondrial Reactive Oxygen Species Production of Ectothermic and Endothermic Fish Muscle

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    Lilian Wiens

    2017-09-01

    Full Text Available Recently we demonstrated that the capacity of isolated muscle mitochondria to produce reactive oxygen species, measured as H2O2 efflux, is temperature-sensitive in isolated muscle mitochondria of ectothermic fish and the rat, a representative endothermic mammal. However, at physiological temperatures (15° and 37°C for the fish and rat, respectively, the fraction of total mitochondrial electron flux that generated H2O2, the fractional electron leak (FEL, was far lower in the rat than in fish. Those results suggested that the elevated body temperatures associated with endothermy may lead to a compensatory decrease in mitochondrial ROS production relative to respiratory capacity. To test this hypothesis we compare slow twitch (red muscle mitochondria from the endothermic Pacific bluefin tuna (Thunnus orientalis with mitochondria from three ectothermic fishes [rainbow trout (Oncorhynchus mykiss, common carp (Cyprinus carpio, and the lake sturgeon (Acipenser fulvescens] and the rat. At a common assay temperature (25°C rates of mitochondrial respiration and H2O2 efflux were similar in tuna and the other fishes. The thermal sensitivity of fish mitochondria was similar irrespective of ectothermy or endothermy. Comparing tuna to the rat at a common temperature, respiration rates were similar, or lower depending on mitochondrial substrates. FEL was not different across fish species at a common assay temperature (25°C but was markedly higher in fishes than in rat. Overall, endothermy and warming of Pacific Bluefin tuna red muscle may increase the potential for ROS production by muscle mitochondria but the evolution of endothermy in this species is not necessarily associated with a compensatory reduction of ROS production relative to the respiratory capacity of mitochondria.

  11. Compartmentalization of NO signaling cascade in skeletal muscles

    International Nuclear Information System (INIS)

    Buchwalow, Igor B.; Minin, Evgeny A.; Samoilova, Vera E.; Boecker, Werner; Wellner, Maren; Schmitz, Wilhelm; Neumann, Joachim; Punkt, Karla

    2005-01-01

    Skeletal muscle functions regulated by NO are now firmly established. However, the literature on the compartmentalization of NO signaling in myocytes is highly controversial. To address this issue, we examined localization of enzymes engaged in L-arginine-NO-cGMP signaling in the rat quadriceps muscle. Employing immunocytochemical labeling complemented with tyramide signal amplification and electron microscopy, we found NO synthase expressed not only in the sarcolemma, but also along contractile fibers, in the sarcoplasmic reticulum and mitochondria. The expression pattern of NO synthase in myocytes showed striking parallels with the enzymes engaged in L-arginine-NO-cGMP signaling (arginase, phosphodiesterase, and soluble guanylyl cyclase). Our findings are indicative of an autocrine fashion of NO signaling in skeletal muscles at both cellular and subcellular levels, and challenge the notion that the NO generation is restricted to the sarcolemma

  12. Growth hormone secretagogues prevent dysregulation of skeletal muscle calcium homeostasis in a rat model of cisplatin-induced cachexia.

    Science.gov (United States)

    Conte, Elena; Camerino, Giulia Maria; Mele, Antonietta; De Bellis, Michela; Pierno, Sabata; Rana, Francesco; Fonzino, Adriano; Caloiero, Roberta; Rizzi, Laura; Bresciani, Elena; Ben Haj Salah, Khoubaib; Fehrentz, Jean-Alain; Martinez, Jean; Giustino, Arcangela; Mariggiò, Maria Addolorata; Coluccia, Mauro; Tricarico, Domenico; Lograno, Marcello Diego; De Luca, Annamaria; Torsello, Antonio; Conte, Diana; Liantonio, Antonella

    2017-06-01

    Cachexia is a wasting condition associated with cancer types and, at the same time, is a serious and dose-limiting side effect of cancer chemotherapy. Skeletal muscle loss is one of the main characteristics of cachexia that significantly contributes to the functional muscle impairment. Calcium-dependent signaling pathways are believed to play an important role in skeletal muscle decline observed in cachexia, but whether intracellular calcium homeostasis is affected in this situation remains uncertain. Growth hormone secretagogues (GHS), a family of synthetic agonists of ghrelin receptor (GHS-R1a), are being developed as a therapeutic option for cancer cachexia syndrome; however, the exact mechanism by which GHS interfere with skeletal muscle is not fully understood. By a multidisciplinary approach ranging from cytofluorometry and electrophysiology to gene expression and histology, we characterized the calcium homeostasis in fast-twitch extensor digitorum longus (EDL) muscle of adult rats with cisplatin-induced cachexia and established the potential beneficial effects of two GHS (hexarelin and JMV2894) at this level. Additionally, in vivo measures of grip strength and of ultrasonography recordings allowed us to evaluate the functional impact of GHS therapeutic intervention. Cisplatin-treated EDL muscle fibres were characterized by a ~18% significant reduction of the muscle weight and fibre diameter together with an up-regulation of atrogin1/Murf-1 genes and a down-regulation of Pgc1-a gene, all indexes of muscle atrophy, and by a two-fold increase in resting intracellular calcium, [Ca 2+ ] i , compared with control rats. Moreover, the amplitude of the calcium transient induced by caffeine or depolarizing high potassium solution as well as the store-operated calcium entry were ~50% significantly reduced in cisplatin-treated rats. Calcium homeostasis dysregulation parallels with changes of functional ex vivo (excitability and resting macroscopic conductance) and in

  13. 8-oxoguanine DNA glycosylase (OGG1 deficiency elicits coordinated changes in lipid and mitochondrial metabolism in muscle.

    Directory of Open Access Journals (Sweden)

    Vladimir Vartanian

    Full Text Available Oxidative stress resulting from endogenous and exogenous sources causes damage to cellular components, including genomic and mitochondrial DNA. Oxidative DNA damage is primarily repaired via the base excision repair pathway that is initiated by DNA glycosylases. 8-oxoguanine DNA glycosylase (OGG1 recognizes and cleaves oxidized and ring-fragmented purines, including 8-oxoguanine, the most commonly formed oxidative DNA lesion. Mice lacking the OGG1 gene product are prone to multiple features of the metabolic syndrome, including high-fat diet-induced obesity, hepatic steatosis, and insulin resistance. Here, we report that OGG1-deficient mice also display skeletal muscle pathologies, including increased muscle lipid deposition and alterations in genes regulating lipid uptake and mitochondrial fission in skeletal muscle. In addition, expression of genes of the TCA cycle and of carbohydrate and lipid metabolism are also significantly altered in muscle of OGG1-deficient mice. These tissue changes are accompanied by marked reductions in markers of muscle function in OGG1-deficient animals, including decreased grip strength and treadmill endurance. Collectively, these data indicate a role for skeletal muscle OGG1 in the maintenance of optimal tissue function.

  14. Skeletal muscle protein synthesis and the abundance of the mRNA translation initiation repressor PDCD4 are inversely regulated by fasting and refeeding in rats.

    Science.gov (United States)

    Zargar, Sana; Moreira, Tracy S; Samimi-Seisan, Helena; Jeganathan, Senthure; Kakade, Dhanshri; Islam, Nushaba; Campbell, Jonathan; Adegoke, Olasunkanmi A J

    2011-06-01

    Optimal skeletal muscle mass is vital to human health, because defects in muscle protein metabolism underlie or exacerbate human diseases. The mammalian target of rapamycin complex 1 is critical in the regulation of mRNA translation and protein synthesis. These functions are mediated in part by the ribosomal protein S6 kinase 1 (S6K1) through mechanisms that are poorly understood. The tumor suppressor programmed cell death 4 (PDCD4) has been identified as a novel substrate of S6K1. Here, we examined 1) the expression of PDCD4 in skeletal muscle and 2) its regulation by feed deprivation (FD) and refeeding. Male rats (~100 g; n = 6) were subjected to FD for 48 h; some rats were refed for 2 h. FD suppressed muscle fractional rates of protein synthesis and Ser(67) phosphorylation of PDCD4 (-50%) but increased PDCD4 abundance (P muscle fractional rates of protein synthesis and reduced PDCD4 abundance relative to FD. Finally, when myoblasts were grown in amino acid- and serum-free medium, phenylalanine incorporation into proteins in cells depleted of PDCD4 more than doubled the values in cells with a normal level of PDCD4 (P skeletal muscle in parallel with the reduction of the abundance of this mRNA translation inhibitor.

  15. Imaging of human sodium-iodide symporter gene expression mediated by recombinant adenovirus in skeletal muscle of living rats

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hyun Suk; Park, Seong-Wook [Department of Internal Medicine (Cardiology), Asan Medical Center, University of Ulsan College of Medicine, 388-1 Pungnap-dong, Songpa-gu, 138-736, Seoul (Korea); Lee, Heuiran; Kim, Sung Jin [Department of Microbiology, University of Ulsan College of Medicine, Seoul (Korea); Lee, Won Woo [Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seongnam (Korea); Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea); Yang, You-Jung; Moon, Dae Hyuk [Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea)

    2004-09-01

    We evaluated the feasibility of non-invasive imaging of recombinant adenovirus-mediated human sodium-iodide symporter (hNIS) gene expression by {sup 99m}TcO{sub 4}{sup -} scintigraphy in skeletal muscle of rats. Replication-defective recombinant adenovirus encoding hNIS gene [Rad-CMV-hNIS 5 x 10{sup 7}, 2 x 10{sup 8} or 1 x 10{sup 9} plaque forming units (pfu)] or {beta}-galactosidase gene (Rad-CMV-LacZ 1 x 10{sup 9} pfu) was injected into the right biceps femoris muscle of rats (n=5-6 for each group). Three days after gene transfer, scintigraphy was performed using a gamma camera 30 min after injection of {sup 99m}TcO{sub 4}{sup -} (1.85 MBq). An additional two rats injected with 1 x 10{sup 9} pfu of Rad-CMV-hNIS underwent {sup 99m}TcO{sub 4}{sup -} scintigraphy with sodium perchlorate. After the imaging studies, rats were sacrificed for assessment of the biodistribution of {sup 99m}TcO{sub 4}{sup -} and measurement of hNIS mRNA expression. In all the rats injected with 1 x 10{sup 9} pfu of Rad-CMV-hNIS, hNIS expression was successfully imaged by {sup 99m}TcO{sub 4}{sup -} scintigraphy, while rats injected with Rad-CMV-LacZ or lower doses of Rad-CMV-hNIS failed to show uptake. The biodistribution studies indicated that a significantly different amount of {sup 99m}TcO{sub 4}{sup -} was retained in the liver (p<0.001) and the right muscle (p<0.05), with the highest uptake in rats injected with 1 x 10{sup 9} pfu of Rad-CMV-hNIS. The muscular hNIS mRNA level quantified by real-time reverse transcription-polymerase chain reaction was significantly higher in rats injected with 1 x 10{sup 9} pfu of Rad-CMV-hNIS (p<0.05), with a positive correlation with the imaging counts (r=0.810, p<0.05) and the biodistribution (r=0.847, p<0.001). Hot spots in rats injected with 1 x 10{sup 9} pfu of Rad-CMV-hNIS were specifically inhibited by sodium perchlorate. This study illustrated that {sup 99m}TcO{sub 4}{sup -} scintigraphy can monitor Rad-CMV-hNIS-mediated gene expression in

  16. Response of skeletal muscle mitochondria to hypoxia.

    Science.gov (United States)

    Hoppeler, Hans; Vogt, Michael; Weibel, Ewald R; Flück, Martin

    2003-01-01

    This review explores the current concepts relating the structural and functional modifications of skeletal muscle mitochondria to the molecular mechanisms activated when organisms are exposed to a hypoxic environment. In contrast to earlier assumptions it is now established that permanent or long-term exposure to severe environmental hypoxia decreases the mitochondrial content of muscle fibres. Oxidative muscle metabolism is shifted towards a higher reliance on carbohydrates as a fuel, and intramyocellular lipid substrate stores are reduced. Moreover, in muscle cells of mountaineers returning from the Himalayas, we find accumulations of lipofuscin, believed to be a mitochondrial degradation product. Low mitochondrial contents are also observed in high-altitude natives such as Sherpas. In these subjects high-altitude performance seems to be improved by better coupling between ATP demand and supply pathways as well as better metabolite homeostasis. The hypoxia-inducible factor 1 (HIF-1) has been identified as a master regulator for the expression of genes involved in the hypoxia response, such as genes coding for glucose transporters, glycolytic enzymes and vascular endothelial growth factor (VEGF). HIF-1 achieves this by binding to hypoxia response elements in the promoter regions of these genes, whereby the increase of HIF-1 in hypoxia is the consequence of a reduced degradation of its dominant subunit HIF-1a. A further mechanism that seems implicated in the hypoxia response of muscle mitochondria is related to the formation of reactive oxygen species (ROS) in mitochondria during oxidative phosphorylation. How exactly ROS interfere with HIF-1a as well as MAP kinase and other signalling pathways is debated. The current evidence suggests that mitochondria themselves could be important players in oxygen sensing.

  17. Inferring the transcriptional landscape of bovine skeletal muscle by integrating co-expression networks.

    Directory of Open Access Journals (Sweden)

    Nicholas J Hudson

    Full Text Available BACKGROUND: Despite modern technologies and novel computational approaches, decoding causal transcriptional regulation remains challenging. This is particularly true for less well studied organisms and when only gene expression data is available. In muscle a small number of well characterised transcription factors are proposed to regulate development. Therefore, muscle appears to be a tractable system for proposing new computational approaches. METHODOLOGY/PRINCIPAL FINDINGS: Here we report a simple algorithm that asks "which transcriptional regulator has the highest average absolute co-expression correlation to the genes in a co-expression module?" It correctly infers a number of known causal regulators of fundamental biological processes, including cell cycle activity (E2F1, glycolysis (HLF, mitochondrial transcription (TFB2M, adipogenesis (PIAS1, neuronal development (TLX3, immune function (IRF1 and vasculogenesis (SOX17, within a skeletal muscle context. However, none of the canonical pro-myogenic transcription factors (MYOD1, MYOG, MYF5, MYF6 and MEF2C were linked to muscle structural gene expression modules. Co-expression values were computed using developing bovine muscle from 60 days post conception (early foetal to 30 months post natal (adulthood for two breeds of cattle, in addition to a nutritional comparison with a third breed. A number of transcriptional landscapes were constructed and integrated into an always correlated landscape. One notable feature was a 'metabolic axis' formed from glycolysis genes at one end, nuclear-encoded mitochondrial protein genes at the other, and centrally tethered by mitochondrially-encoded mitochondrial protein genes. CONCLUSIONS/SIGNIFICANCE: The new module-to-regulator algorithm complements our recently described Regulatory Impact Factor analysis. Together with a simple examination of a co-expression module's contents, these three gene expression approaches are starting to illuminate the in vivo

  18. Docosahexaenoic acid and n-6 docosapentaenoic acid supplementation alter rat skeletal muscle fatty acid composition

    Directory of Open Access Journals (Sweden)

    Lim Sun-Young

    2007-04-01

    Full Text Available Abstract Background Docosahexaenoic acid (22:6n-3, DHA and n-6 docosapentaenoic acid (22:5n-6, DPAn-6 are highly unsaturated fatty acids (HUFA, ≥ 20 carbons, ≥ 3 double bonds that differ by a single carbon-carbon double bond at the Δ19 position. Membrane 22:6n-3 may support skeletal muscle function through optimal ion pump activity of sarcoplasmic reticulum and electron transport in the mitochondria. Typically n-3 fatty acid deficient feeding trials utilize linoleic acid (18:2n-6, LA as a comparison group, possibly introducing a lower level of HUFA in addition to n-3 fatty acid deficiency. The use of 22:5n-6 as a dietary control is ideal for determining specific requirements for 22:6n-3 in various physiological processes. The incorporation of dietary 22:5n-6 into rat skeletal muscles has not been demonstrated previously. A one generation, artificial rearing model was utilized to supply 22:6n-3 and/or 22:5n-6 to rats from d2 after birth to adulthood. An n-3 fatty acid deficient, artificial milk with 18:2n-6 was supplemented with 22:6n-3 and/or 22:5n-6 resulting in four artificially reared (AR dietary groups; AR-LA, AR-DHA, AR-DPAn-6, AR-DHA+DPAn-6. A dam reared group (DAM was included as an additional control. Animals were sacrificed at 15 wks and soleus, white gastrocnemius and red gastrocnemius muscles were collected for fatty acid analyses. Results In all muscles of the DAM group, the concentration of 22:5n-6 was significantly lower than 22:6n-3 concentrations. While 22:5n-6 was elevated in the AR-LA group and the AR-DPAn-6 group, 20:4n-6 tended to be higher in the AR-LA muscles and not in the AR-DPAn-6 muscles. The AR-DHA+DPAn-6 had a slight, but non-significant increase in 22:5n-6 content. In the red gastrocnemius of the AR-DPAn-6 group, 22:5n-6 levels (8.1 ± 2.8 wt. % did not reciprocally replace the 22:6n-3 levels observed in AR-DHA reared rats (12.2 ± 2.3 wt. % suggesting a specific preference/requirement for 22:6n-3 in red

  19. The Effects of Long-Term Experimental Diabetes Mellitus Type I on Skeletal Muscle Regeneration Capacity

    OpenAIRE

    Jerković, Romana; Bosnar, Alan; Jurišić-Eržen, Dubravka; Ažman, Josip; Starčević-Klasan, Gordana; Peharec, Stanislav; Čoklo, Miran

    2009-01-01

    Muscle fibers are dynamic structures capable of altering their phenotype under various pathological conditions. The aim of the present study was to investigate the influence of long-lasting diabetes mellitus on the process of muscle regeneration in the skeletal muscle. Wistar rats were made diabetic by a single intraperitoneal injection of streptozotocin (STZ). The regeneration process in the skeletal muscle was induced in slow (m. soleus, SOL) and fast (m. extensor digitorum longus, EDL) mus...

  20. Lactate oxidation in human skeletal muscle mitochondria

    DEFF Research Database (Denmark)

    Jacobs, Robert A; Meinild, Anne-Kristine; Nordsborg, Nikolai B

    2013-01-01

    of four separate and specific substrate titration protocols, the respirometric analysis revealed that mitochondria were capable of oxidizing lactate in the absence of exogenous LDH. The titration of lactate and NAD(+) into the respiration medium stimulated respiration (P = 0.003). The addition...... of exogenous LDH failed to increase lactate-stimulated respiration (P = 1.0). The results further demonstrate that human skeletal muscle mitochondria cannot directly oxidize lactate within the mitochondrial matrix. Alternately, these data support previous claims that lactate is converted to pyruvate within...

  1. High-resolution respirometry of fine-needle muscle biopsies in pre-manifest Huntington's disease expansion mutation carriers shows normal mitochondrial respiratory function.

    Directory of Open Access Journals (Sweden)

    Eva Buck

    Full Text Available Alterations in mitochondrial respiration are an important hallmark of Huntington's disease (HD, one of the most common monogenetic causes of neurodegeneration. The ubiquitous expression of the disease causing mutant huntingtin gene raises the prospect that mitochondrial respiratory deficits can be detected in skeletal muscle. While this tissue is readily accessible in humans, transgenic animal models offer the opportunity to cross-validate findings and allow for comparisons across organs, including the brain. The integrated respiratory chain function of the human vastus lateralis muscle was measured by high-resolution respirometry (HRR in freshly taken fine-needle biopsies from seven pre-manifest HD expansion mutation carriers and nine controls. The respiratory parameters were unaffected. For comparison skeletal muscle isolated from HD knock-in mice (HdhQ111 as well as a broader spectrum of tissues including cortex, liver and heart muscle were examined by HRR. Significant changes of mitochondrial respiration in the HdhQ knock-in mouse model were restricted to the liver and the cortex. Mitochondrial mass as quantified by mitochondrial DNA copy number and citrate synthase activity was stable in murine HD-model tissue compared to control. mRNA levels of key enzymes were determined to characterize mitochondrial metabolic pathways in HdhQ mice. We demonstrated the feasibility to perform high-resolution respirometry measurements from small human HD muscle biopsies. Furthermore, we conclude that alterations in respiratory parameters of pre-manifest human muscle biopsies are rather limited and mirrored by a similar absence of marked alterations in HdhQ skeletal muscle. In contrast, the HdhQ111 murine cortex and liver did show respiratory alterations highlighting the tissue specific nature of mutant huntingtin effects on respiration.

  2. The role of extracellular matrix in lateral transmission of force in skeletal muscle

    Science.gov (United States)

    Gao, Yingxin

    This dissertation describes the role of extracellular matrix (ECM) in the lateral transmission of force. It consists of an experimental studies of the ECM and mathematical modeling of lateral transmission of force. The effect of aging on the structural and mechanical properties of the epimysium of muscle of the rats were examined. No statistically significant differences were found in the ultrastructure, or the thickness of the epimysium. However, from the tensile stress-strain tests, it was found that the epimysium of muscles from old rats was much stiffer than that of the young rats. Based on these observations. It was concluded that the differences in the mechanical properties of the epimysium of the muscles from the old compared with young rats were not associated with the arrangement and size of collagen fibers in the epimysium. Consequently, other methods will be required to identify the structural bases of the mechanical differences. The stress-strain relationships for the epimysiums of the skeletal muscles from both the young and old rats were found to be nonlinear. A mathematical model was developed that showed that the nonlinear behavior results from the waviness and the reorientation of the collagen fibers in the epimysium. The ECM plays an important role in lateral transmission of force in skeletal muscle by providing shear stress between the muscle fibers or fascicles. A mathematical model was developed to investigate the mechanisms of lateral transmission. It was a modification of the shear lag theory for chopped fiber composite materials used in engineering applications. The modified shear lag theory includes an activation strain to account for muscle contraction and a myofibrils-endomysium interfaces that accounts for the molecular lateral linkages. The model was used to simulate the classic experiments of Street. It was demonstrated that lateral transmission of force in the skeletal muscle is affected by the mechanical and structural properties of

  3. The regulation of mitochondrial transcription factor A (Tfam) expression during skeletal muscle cell differentiation.

    Science.gov (United States)

    Collu-Marchese, Melania; Shuen, Michael; Pauly, Marion; Saleem, Ayesha; Hood, David A

    2015-05-19

    The ATP demand required for muscle development is accommodated by elevations in mitochondrial biogenesis, through the co-ordinated activities of the nuclear and mitochondrial genomes. The most important transcriptional activator of the mitochondrial genome is mitochondrial transcription factor A (Tfam); however, the regulation of Tfam expression during muscle differentiation is not known. Thus, we measured Tfam mRNA levels, mRNA stability, protein expression and localization and Tfam transcription during the progression of muscle differentiation. Parallel 2-fold increases in Tfam protein and mRNA were observed, corresponding with 2-3-fold increases in mitochondrial content. Transcriptional activity of a 2051 bp promoter increased during this differentiation period and this was accompanied by a 3-fold greater Tfam mRNA stabilization. Interestingly, truncations of the promoter at 1706 bp, 978 bp and 393 bp promoter all exhibited 2-3-fold higher transcriptional activity than the 2051 bp construct, indicating the presence of negative regulatory elements within the distal 350 bp of the promoter. Activation of AMP kinase augmented Tfam transcription within the proximal promoter, suggesting the presence of binding sites for transcription factors that are responsive to cellular energy state. During differentiation, the accumulating Tfam protein was progressively distributed to the mitochondrial matrix where it augmented the expression of mtDNA and COX (cytochrome c oxidase) subunit I, an mtDNA gene product. Our data suggest that, during muscle differentiation, Tfam protein levels are regulated by the availability of Tfam mRNA, which is controlled by both transcription and mRNA stability. Changes in energy state and Tfam localization also affect Tfam expression and action in differentiating myotubes. © 2015 Authors.

  4. Opposite effects of pioglitazone and rosiglitazone on mitochondrial respiration in skeletal muscle of patients with type 2 diabetes

    DEFF Research Database (Denmark)

    Rabøl, R; Boushel, R; Almdal, T

    2010-01-01

    mitochondrial respiration per milligram muscle was measured in saponin-treated skinned muscle fibres using high-resolution respirometry. RESULTS: Mitochondrial respiration per milligram muscle was lower in T2DM compared to controls at baseline and decreased during ROSI treatment but increased during PIO...... of ROSI and PIO on mitochondrial respiration, and also show that insulin sensitivity can be improved independently of changes in mitochondrial respiration. We confirm that mitochondrial respiration is reduced in T2DM compared to age- and BMI-matched control subjects....

  5. Changes in Whole-Body Oxygen Consumption and Skeletal Muscle Mitochondria During Linezolid-Induced Lactic Acidosis.

    Science.gov (United States)

    Protti, Alessandro; Ronchi, Dario; Bassi, Gabriele; Fortunato, Francesco; Bordoni, Andreina; Rizzuti, Tommaso; Fumagalli, Roberto

    2016-07-01

    To better clarify the pathogenesis of linezolid-induced lactic acidosis. Case report. ICU. A 64-year-old man who died with linezolid-induced lactic acidosis. Skeletal muscle was sampled at autopsy to study mitochondrial function. Lactic acidosis developed during continuous infusion of linezolid while oxygen consumption and oxygen extraction were diminishing from 172 to 52 mL/min/m and from 0.27 to 0.10, respectively. Activities of skeletal muscle respiratory chain complexes I, III, and IV, encoded by nuclear and mitochondrial DNA, were abnormally low, whereas activity of complex II, entirely encoded by nuclear DNA, was not. Protein studies confirmed stoichiometric imbalance between mitochondrial (cytochrome c oxidase subunits 1 and 2) and nuclear (succinate dehydrogenase A) DNA-encoded respiratory chain subunits. These findings were not explained by defects in mitochondrial DNA or transcription. There were no compensatory mitochondrial biogenesis (no induction of nuclear respiratory factor 1 and mitochondrial transcript factor A) or adaptive unfolded protein response (reduced concentration of heat shock proteins 60 and 70). Linezolid-induced lactic acidosis is associated with diminished global oxygen consumption and extraction. These changes reflect selective inhibition of mitochondrial protein synthesis (probably translation) with secondary mitonuclear imbalance. One novel aspect of linezolid toxicity that needs to be confirmed is blunting of reactive mitochondrial biogenesis and unfolded protein response.

  6. Bimodal effect on pancreatic β-cells of secretory products from normal or insulin-resistant human skeletal muscle

    DEFF Research Database (Denmark)

    Bouzakri, Karim; Plomgaard, Peter; Berney, Thierry

    2011-01-01

    Type 2 diabetes is characterized by insulin resistance with a relative deficiency in insulin secretion. This study explored the potential communication between insulin-resistant human skeletal muscle and primary (human and rat) β-cells.......Type 2 diabetes is characterized by insulin resistance with a relative deficiency in insulin secretion. This study explored the potential communication between insulin-resistant human skeletal muscle and primary (human and rat) β-cells....

  7. Skeletal muscle performance and ageing.

    Science.gov (United States)

    Tieland, Michael; Trouwborst, Inez; Clark, Brian C

    2018-02-01

    The world population is ageing rapidly. As society ages, the incidence of physical limitations is dramatically increasing, which reduces the quality of life and increases healthcare expenditures. In western society, ~30% of the population over 55 years is confronted with moderate or severe physical limitations. These physical limitations increase the risk of falls, institutionalization, co-morbidity, and premature death. An important cause of physical limitations is the age-related loss of skeletal muscle mass, also referred to as sarcopenia. Emerging evidence, however, clearly shows that the decline in skeletal muscle mass is not the sole contributor to the decline in physical performance. For instance, the loss of muscle strength is also a strong contributor to reduced physical performance in the elderly. In addition, there is ample data to suggest that motor coordination, excitation-contraction coupling, skeletal integrity, and other factors related to the nervous, muscular, and skeletal systems are critically important for physical performance in the elderly. To better understand the loss of skeletal muscle performance with ageing, we aim to provide a broad overview on the underlying mechanisms associated with elderly skeletal muscle performance. We start with a system level discussion and continue with a discussion on the influence of lifestyle, biological, and psychosocial factors on elderly skeletal muscle performance. Developing a broad understanding of the many factors affecting elderly skeletal muscle performance has major implications for scientists, clinicians, and health professionals who are developing therapeutic interventions aiming to enhance muscle function and/or prevent mobility and physical limitations and, as such, support healthy ageing. © 2017 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of the Society on Sarcopenia, Cachexia and Wasting Disorders.

  8. Spot light on skeletal muscles: optogenetic stimulation to understand and restore skeletal muscle function.

    Science.gov (United States)

    van Bremen, Tobias; Send, Thorsten; Sasse, Philipp; Bruegmann, Tobias

    2017-08-01

    Damage of peripheral nerves results in paralysis of skeletal muscle. Currently, the only treatment option to restore proper function is electrical stimulation of the innervating nerve or of the skeletal muscles directly. However this approach has low spatial and temporal precision leading to co-activation of antagonistic muscles and lacks cell-type selectivity resulting in pain or discomfort by stimulation of sensible nerves. In contrast to electrical stimulation, optogenetic methods enable spatially confined and cell-type selective stimulation of cells expressing the light sensitive channel Channelrhodopsin-2 with precise temporal control over the membrane potential. Herein we summarize the current knowledge about the use of this technology to control skeletal muscle function with the focus on the direct, non-neuronal stimulation of muscle fibers. The high temporal flexibility of using light pulses allows new stimulation patterns to investigate skeletal muscle physiology. Furthermore, the high spatial precision of focused illumination was shown to be beneficial for selective stimulation of distinct nearby muscle groups. Finally, the cell-type specific expression of the light-sensitive effector proteins in muscle fibers will allow pain-free stimulation and open new options for clinical treatments. Therefore, we believe that direct optogenetic stimulation of skeletal muscles is a very potent method for basic scientists that also harbors several distinct advantages over electrical stimulation to be considered for clinical use in the future.

  9. Contractions but not AICAR increase FABPpm content in rat muscle sarcolemma

    DEFF Research Database (Denmark)

    Jeppesen, Jacob; Albers, Peter; Luiken, Joost J.

    2009-01-01

    FAT/CD36 and FABPpm protein expression, measured in lysates with western blotting, by either stimulus. AMPK thr172 and ERK1/2 thr202/204 phosphorylation were significantly increased with muscle contractions (P ...In the present study, it was investigated whether acute muscle contractions in rat skeletal muscle increased the protein content of FABPpm in the plasma membrane. Furthermore, the effect of AICAR stimulation on FAT/CD36 and FABPpm protein content in sarcolemma of rat skeletal muscle was evaluated....... METHODS: Male wistar rats (150 g) were anesthetized and either subjected to in situ electrically induced contractions (hindlimb muscles: 20 min, 10-20 V, 200 ms trains, 100 Hz) or stimulated with the pharmacological activator of AMPK, AICAR. To investigate changes in the content of FABPpm and FAT/CD36...

  10. Detection of satellite cells during skeletal muscle wound healing in rats: time-dependent expressions of Pax7 and MyoD in relation to wound age.

    Science.gov (United States)

    Tian, Zhi-Ling; Jiang, Shu-Kun; Zhang, Miao; Wang, Meng; Li, Jiao-Yong; Zhao, Rui; Wang, Lin-Lin; Li, Shan-Shan; Liu, Min; Zhang, Meng-Zhou; Guan, Da-Wei

    2016-01-01

    The study was focused on time-dependent expressions of paired-box transcription factor 7 (Pax7) and myoblast determination protein (MyoD) during skeletal muscle wound healing. An animal model of skeletal muscle contusion was established in 40 Sprague-Dawley male rats. Samples were taken at 1, 3, 5, 7, 9, 13, 17, and 21 days after injury, respectively (five rats in each posttraumatic interval). Five rats were employed as control. By morphometric analysis, the data based on the number of Pax7(+)/MyoD(-), Pax7(+)/MyoD(+), and Pax7(-)/MyoD(+) cells were highly correlated with the wound age. Pax7 and MyoD expressions were upregulated after injury by Western blot and quantitative real-time PCR assays. The relative quantity of Pax7 protein peaked at 5 days after injury, which was >1.13, and decreased thereafter. Similarly, the relative quantity of MyoD mRNA expression peaked at 3 days after injury, which was >2.59. The relative quantity of Pax7 protein >0.73 or mRNA expression >2.38 or the relative quantity of MyoD protein >1.33 suggested a wound age of 3 to 7 days. The relative quantity of MyoD mRNA expression >2.02 suggested a wound age of 1 to 7 days post-injury. In conclusion, the expressions of Pax7 and MyoD are upregulated in a time-dependent manner during skeletal muscle wound healing, suggesting that Pax7 and MyoD may be potential markers for wound age estimation in skeletal muscle.

  11. Bed rest reduces metabolic protein content and abolishes exercise-induced mRNA responses in human skeletal muscle

    DEFF Research Database (Denmark)

    Jørgensen, Stine Ringholm; Biensø, Rasmus S; Kiilerich, Kristian

    2011-01-01

    Background: The aim was to test the hypothesis that one week of bed rest will reduce mitochondrial number and expression and activity of oxidative proteins in human skeletal muscle, but that exercise-induced intracellular signaling as well as mRNA and microRNA (miR) responses are maintained after......-legged knee extensor exercise performed before and after bed rest. Results: Maximal oxygen uptake decreased 5% and exercise endurance decreased non-significantly 25% by bed rest. Bed rest reduced skeletal muscle mitochondrial DNA/nuclear DNA content 15%, hexokinase II and sirtuin 1 protein content ~45%, 3...... bed rest. Research Design and Methods: Twelve young, healthy, male subjects completed 7 days of bed rest with vastus lateralis muscle biopsies taken before and after bed rest. In addition, muscle biopsies were obtained from 6 of the subjects prior to, immediately after and 3h after 45 min one...

  12. Training-induced adaptation of oxidative phosphorylation in skeletal muscles.

    Science.gov (United States)

    Korzeniewski, Bernard; Zoladz, Jerzy A

    2003-08-15

    Muscle training/conditioning improves the adaptation of oxidative phosphorylation in skeletal muscles to physical exercise. However, the mechanisms underlying this adaptation are still not understood fully. By quantitative analysis of the existing experimental results, we show that training-induced acceleration of oxygen-uptake kinetics at the onset of exercise and improvement of ATP/ADP stability due to physical training are mainly caused by an increase in the amount of mitochondrial proteins and by an intensification of the parallel activation of ATP usage and ATP supply (increase in direct stimulation of oxidative phosphorylation complexes accompanying stimulation of ATP consumption) during exercise.

  13. Regulation of mitochondrial respiration by inorganic phosphate; comparing permeabilized muscle fibers and isolated mitochondria prepared from type-1 and type-2 rat skeletal muscle

    DEFF Research Database (Denmark)

    Scheibye-Knudsen, Morten; Quistorff, Bjørn

    2008-01-01

    ADP is generally accepted as a key regulator of oxygen consumption both in isolated mitochondria and in permeabilized fibers from skeletal muscle. The present study explored inorganic phosphate in a similar regulatory role. Saponin permeabilized fibers and isolated mitochondria from type-I and type...

  14. Narciclasine attenuates diet-induced obesity by promoting oxidative metabolism in skeletal muscle.

    Directory of Open Access Journals (Sweden)

    Sofi G Julien

    2017-02-01

    Full Text Available Obesity develops when caloric intake exceeds metabolic needs. Promoting energy expenditure represents an attractive approach in the prevention of this fast-spreading epidemic. Here, we report a novel pharmacological strategy in which a natural compound, narciclasine (ncls, attenuates diet-induced obesity (DIO in mice by promoting energy expenditure. Moreover, ncls promotes fat clearance from peripheral metabolic tissues, improves blood metabolic parameters in DIO mice, and protects these mice from the loss of voluntary physical activity. Further investigation suggested that ncls achieves these beneficial effects by promoting a shift from glycolytic to oxidative muscle fibers in the DIO mice thereby enhancing mitochondrial respiration and fatty acid oxidation (FAO in the skeletal muscle. Moreover, ncls strongly activates AMPK signaling specifically in the skeletal muscle. The beneficial effects of ncls treatment in fat clearance and AMPK activation were faithfully reproduced in vitro in cultured murine and human primary myotubes. Mechanistically, ncls increases cellular cAMP concentration and ADP/ATP ratio, which further lead to the activation of AMPK signaling. Blocking AMPK signaling through a specific inhibitor significantly reduces FAO in myotubes. Finally, ncls also enhances mitochondrial membrane potential and reduces the formation of reactive oxygen species in cultured myotubes.

  15. Activated protein C attenuates acute ischaemia reperfusion injury in skeletal muscle.

    LENUS (Irish Health Repository)

    Dillon, J P

    2012-02-03

    Activated protein C (APC) is an endogenous anti-coagulant with anti-inflammatory properties. The purpose of the present study was to evaluate the effects of activated protein C in the setting of skeletal muscle ischaemia reperfusion injury (IRI). IRI was induced in rats by applying rubber bands above the levels of the greater trochanters bilaterally for a period of 2h followed by 12h reperfusion. Treatment groups received either equal volumes of normal saline or activated protein C prior to tourniquet release. Following 12h reperfusion, muscle function was assessed electrophysiologically by electrical field stimulation. The animals were then sacrificed and skeletal muscle harvested for evaluation. Activated protein C significantly attenuated skeletal muscle reperfusion injury as shown by reduced myeloperoxidase content, wet to dry ratio and electrical properties of skeletal muscle. Further in vitro work was carried out on neutrophils isolated from healthy volunteers to determine the direct effect of APC on neutrophil function. The effects of APC on TNF-alpha stimulated neutrophils were examined by measuring CD18 expression as well as reactive oxygen species generation. The in vitro work demonstrated a reduction in CD18 expression and reactive oxygen species generation. We conclude that activated protein C may have a protective role in the setting of skeletal muscle ischaemia reperfusion injury and that this is in part mediated by a direct inhibitory effect on neutrophil activation.

  16. Redox Control of Skeletal Muscle Regeneration.

    Science.gov (United States)

    Le Moal, Emmeran; Pialoux, Vincent; Juban, Gaëtan; Groussard, Carole; Zouhal, Hassane; Chazaud, Bénédicte; Mounier, Rémi

    2017-08-10

    Skeletal muscle shows high plasticity in response to external demand. Moreover, adult skeletal muscle is capable of complete regeneration after injury, due to the properties of muscle stem cells (MuSCs), the satellite cells, which follow a tightly regulated myogenic program to generate both new myofibers and new MuSCs for further needs. Although reactive oxygen species (ROS) and reactive nitrogen species (RNS) have long been associated with skeletal muscle physiology, their implication in the cell and molecular processes at work during muscle regeneration is more recent. This review focuses on redox regulation during skeletal muscle regeneration. An overview of the basics of ROS/RNS and antioxidant chemistry and biology occurring in skeletal muscle is first provided. Then, the comprehensive knowledge on redox regulation of MuSCs and their surrounding cell partners (macrophages, endothelial cells) during skeletal muscle regeneration is presented in normal muscle and in specific physiological (exercise-induced muscle damage, aging) and pathological (muscular dystrophies) contexts. Recent advances in the comprehension of these processes has led to the development of therapeutic assays using antioxidant supplementation, which result in inconsistent efficiency, underlying the need for new tools that are aimed at precisely deciphering and targeting ROS networks. This review should provide an overall insight of the redox regulation of skeletal muscle regeneration while highlighting the limits of the use of nonspecific antioxidants to improve muscle function. Antioxid. Redox Signal. 27, 276-310.

  17. Effects of low level laser in the morphology of the skeletal muscle fiber during compensatory hypertrophy in plantar muscle of rats

    Science.gov (United States)

    Terena, Stella Maris Lins; Fernandes, Kristianne Porta Santos; Kalil, Sandra; Alves, Agnelo Neves; Mesquita Ferrari, Raquel Agnelli

    2015-06-01

    The hypertrophy is known as an increase the cross-sectional area of the muscle as a result of a muscular work against an overload, and it is compensatory because the overload is induced by functional elimination of synergistic muscles. The importance of study the compensatory hypertrophy is understand how this process can be influenced by the irradiation with regard to the weight and muscle cross-sectional area, to assist in the rehabilitation process and the effectiveness functional return. The aim was evaluate the effects of low-level laser irradiation on morphological aspects of muscle tissue, comparing the weight and cross-sectional area in rat skeletal muscle. Wistar rats were divided into three groups: control, hypertrophy group without irradiation (right plantar muscle) and hypertrophy group and irradiation (left plantar muscle), both analyzed after 7 and 14 days. The irradiation was performed daily immediately after the surgery. The parameters were: λ = 780nm, beam spot of 0.04 cm2, output power of 40mW, power density of 1W/cm2, energy density of 10J / cm2 and 10s exposure time with a total energy of 3.2 J. The results revealed that low level laser irradiation an increase the weight of the plantaris muscle after 7 and 14 days with a difference of 7.06% and 11.51% respectively. In conclusion, low level laser irradiation has an effect on compensatory hypertrophy to produce increased muscle weight and promoted an increase in cross-sectional area of muscle fibers in the compensatory hypertrophy model after 14 days with parameters cited above.

  18. UCP2 muscle gene transfer modifies mitochondrial membrane potential.

    Science.gov (United States)

    Marti, A; Larrarte, E; Novo, F J; Garcia, M; Martinez, J A

    2001-01-01

    The aim of this work was to evaluate the effect of uncoupling protein 2 (UCP2) muscle gene transfer on mitochondrial activity. Five week-old male Wistar rats received an intramuscular injection of plasmid pXU1 containing UCP2 cDNA in the right tibialis anterior muscles. Left tibialis anterior muscles were injected with vehicle as control. Ten days after DNA injection, tibialis anterior muscles were dissected and muscle mitochondria isolated and analyzed. There were two mitochondrial populations in the muscle after UCP2 gene transfer, one of low fluorescence and complexity and the other, showing high fluorescence and complexity. UCP2 gene transfer resulted in a 3.6 fold increase in muscle UCP2 protein levels compared to control muscles assessed by Western blotting. Furthermore, a significant reduction in mitochondria membrane potential assessed by spectrofluorometry and flow cytometry was observed. The mitochondria membrane potential reduction might account for a decrease in fluorescence of the low fluorescence mitochondrial subpopulation. It has been demonstrated that UCP2 muscle gene transfer in vivo is associated with a lower mitochondria membrane potential. Our results suggest the potential involvement of UCP2 in uncoupling respiration. International Journal of Obesity (2001) 25, 68-74

  19. Caveolin-3 is associated with the T-tubules of mature skeletal muscle fibers

    DEFF Research Database (Denmark)

    Ralston, E; Ploug, Thorkil

    1999-01-01

    Caveolae are abundant in skeletal muscle and their coat contains a specific isoform of caveolin, caveolin-3. It has been suggested that during muscle development, caveolin-3 is associated with the T-tubules, but that in adult muscle it is found on the plasma membrane only. We have studied...... the distribution of caveolin-3 in single skeletal muscle fibers from adult rat soleus by confocal immunofluorescence and by immunogold electron microscopy. We found that caveolin-3 occurs at the highest density on the plasma membrane but is also present in the core of the fibers, at the I-band/A-band interface...

  20. Exercise increases the plasma membrane content of the Na+ -K+ pump and its mRNA in rat skeletal muscles.

    Science.gov (United States)

    Tsakiridis, T; Wong, P P; Liu, Z; Rodgers, C D; Vranic, M; Klip, A

    1996-02-01

    Muscle fibers adapt to ionic challenges of exercise by increasing the plasma membrane Na+-K+ pump activity. Chronic exercise training has been shown to increase the total amount of Na+-K+ pumps present in skeletal muscle. However, the mechanism of adaptation of the Na+-K+ pump to an acute bout of exercise has not been determined, and it is not known whether it involves alterations in the content of plasma membrane pump subunits. Here we examine the effect of 1 h of treadmill running (20 m/min, 10% grade) on the subcellular distribution and expression of Na+-K+ pump subunits in rat skeletal muscles. Red type I and IIa (red-I/IIa) and white type IIa and IIb (white-IIa/IIb) hindlimb muscles from resting and exercised female Sprague-Dawley rats were removed for subcellular fractionation. By homogenization and gradient centrifugation, crude membranes and purified plasma membranes were isolated and subjected to gel electrophoresis and immunoblotting by using pump subunit-specific antibodies. Furthermore, mRNA was isolated from specific red type I (red-I) and white type IIb (white-IIb) muscles and subjected to Northern blotting by using subunit-specific probes. In both red-I/IIa and white-IIa/IIb muscles, exercise significantly raised the plasma membrane content of the alpha1-subunit of the pump by 64 +/- 24 and 55 +/- 22%, respectively (P < 0.05), and elevated the alpha2-polypeptide by 43 +/- 22 and 94 +/- 39%, respectively (P < 0.05). No significant effect of exercise could be detected on the amount of these subunits in an internal membrane fraction or in total membranes. In addition, exercise significantly increased the alpha1-subunit mRNA in red-I muscle (by 50 +/- 7%; P < 0.05) and the beta2-subunit mRNA in white-IIb muscles (by 64 +/- 19%; P < 0.01), but the alpha2- and beta1-mRNA levels were unaffected in this time period. We conclude that increased presence of alpha1- and alpha2-polypeptides at the plasma membrane and subsequent elevation of the alpha1- and beta2

  1. Relationship of oxidative stress in skeletal muscle with obesity and obesity-associated hyperinsulinemia in horses.

    Science.gov (United States)

    Banse, Heidi E; Frank, Nicholas; Kwong, Grace P S; McFarlane, Dianne

    2015-10-01

    In horses, hyperinsulinemia and insulin resistance (insulin dysregulation) are associated with the development of laminitis. Although obesity is associated with insulin dysregulation, the mechanism of obesity-associated insulin dysregulation remains to be established. We hypothesized that oxidative stress in skeletal muscle is associated with obesity-associated hyperinsulinemia in horses. Thirty-five light breed horses with body condition scores (BCS) of 3/9 to 9/9 were studied, including 7 obese, normoinsulinemic (BCS ≥ 7, resting serum insulin obese, hyperinsulinemic (resting serum insulin ≥ 30 μIU/mL) horses. Markers of oxidative stress (oxidative damage, mitochondrial function, and antioxidant capacity) were evaluated in skeletal muscle biopsies. A Spearman's rank correlation coefficient was used to determine relationships between markers of oxidative stress and BCS. Furthermore, to assess the role of oxidative stress in obesity-related hyperinsulinemia, markers of antioxidant capacity and oxidative damage were compared among lean, normoinsulinemic (L-NI); obese, normoinsulinemic (O-NI); and obese, hyperinsulinemic (O-HI) horses. Increasing BCS was associated with an increase in gene expression of a mitochondrial protein responsible for mitochondrial biogenesis (estrogen-related receptor alpha, ERRα) and with increased antioxidant enzyme total superoxide dismutase (TotSOD) activity. When groups (L-NI, O-NI, and O-HI) were compared, TotSOD activity was increased and protein carbonyls, a marker of oxidative damage, decreased in the O-HI compared to the L-NI horses. These findings suggest that a protective antioxidant response occurred in the muscle of obese animals and that obesity-associated oxidative damage in skeletal muscle is not central to the pathogenesis of equine hyperinsulinemia.

  2. A novel method for determining human ex vivo submaximal skeletal muscle mitochondrial function

    DEFF Research Database (Denmark)

    Hey-Mogensen, Martin; Gram, Martin; Jensen, Martin Borch

    2015-01-01

    previously used. Muscle biopsies were taken from 64 old or young male subjects (60-70 or 20-30 years old). Aged subjects were recruited as trained or untrained. Muscle biopsies were used for isolation of mitochondria and subsequent measurements of DNA repair, antioxidant capacity and mitochondrial protein...

  3. An examination of resveratrol's mechanisms of action in human tissue: impact of a single dose in vivo and dose responses in skeletal muscle ex vivo.

    Directory of Open Access Journals (Sweden)

    Cameron B Williams

    Full Text Available The current study tested the hypothesis that a single, moderate dose of RSV would activate the AMPK/SIRT1 axis in human skeletal muscle and adipose tissue. Additionally, the effects of RSV on mitochondrial respiration in PmFBs were examined. Eight sedentary men (23.8±2.4 yrs; BMI: 32.7±7.1 reported to the lab on two occasions where they were provided a meal supplemented with 300 mg of RSV or a placebo. Blood samples, and a muscle biopsy were obtained in the fasted state and again, with the addition of an adipose tissue biopsy, two hours post-prandial. The effect of RSV on mitochondrial respiration was examined in PmFBs taken from muscle biopsies from an additional eight men (23.4±5.4 yrs; BMI: 24.4±2.8. No effect of RSV was observed on nuclear SIRT1 activity, acetylation of p53, or phosphorylation of AMPK, ACC or PKA in either skeletal muscle or adipose tissue. A decrease in post absorptive insulin levels was accompanied by elevated skeletal muscle phosphorylation of p38 MAPK, but no change in either skeletal muscle or adipose tissue insulin signalling. Mitochondrial respiration in PmFBs was rapidly inhibited by RSV at 100-300 uM depending on the substrate examined. These results question the efficacy of a single dose of RSV at altering skeletal muscle and adipose tissue AMPK/SIRT1 activity in humans and suggest that RSV mechanisms of action in humans may be associated with altered cellular energetics resulting from impaired mitochondrial ATP production.

  4. Autophagy in muscle of glucose-infusion hyperglycemia rats and streptozotocin-induced hyperglycemia rats via selective activation of m-TOR or FoxO3.

    Directory of Open Access Journals (Sweden)

    Pengfei Lv

    Full Text Available Autophagy is a conserved process in eukaryotes required for metabolism and is involved in diverse diseases. To investigate autophagy in skeletal muscle under hyperglycemia status, we established two hyperglycemia-rat models that differ in their circulating insulin levels, by glucose infusion and singe high-dose streptozotocin injection. We then detected expression of autophagy related genes with real-time PCR and western blot. We found that under hyperglycemia status induced by glucose-infusion, autophagy was inhibited in rat skeletal muscle, whereas under streptozotocin-induced hyperglycemia status autophagy was enhanced. Meanwhile, hyperglycemic gastrocnemius muscle was more prone to autophagy than soleus muscle. Furthermore, inhibition of autophagy in skeletal muscle in glucose-infusion hyperglycemia rats was mediated by the m-TOR pathway while m-TOR and FoxO3 both contributed to enhancement of autophagy in gastrocnemius muscle in streptozotocin-induced hyperglycemia rats. These data shows that insulin plays a relatively more important role than hyperglycemia in regulating autophagy in hyperglycemia rat muscle through selectively activating the m-TOR or FoxO3 pathway in a fiber-selective manner.

  5. Fiber Specific Changes in Sphingolipid Metabolism in Skeletal Muscles of Hyperthyroid Rats

    OpenAIRE

    Chabowski, A.; ?endzian-Piotrowska, M.; Mik?osz, A.; ?ukaszuk, B.; Kurek, K.; G?rski, J.

    2013-01-01

    Thyroid hormones (T3, T4) are well known modulators of different cellular signals including the sphingomyelin pathway. However, studies regarding downstream effects of T3 on sphingolipid metabolism in skeletal muscle are scarce. In the present work we sought to investigate the effects of hyperthyroidism on the activity of the key enzymes of ceramide metabolism as well as the content of fundamental sphingolipids. Based on fiber/metabolic differences, we chose three different skeletal muscles, ...

  6. Activation of muscarinic M-1 cholinoceptors by curcumin to increase glucose uptake into skeletal muscle isolated from Wistar rats.

    Science.gov (United States)

    Cheng, Tse-Chou; Lin, Chian-Shiung; Hsu, Chih-Chieh; Chen, Li-Jen; Cheng, Kai-Chun; Cheng, Juei-Tang

    2009-11-20

    Curcumin, an active principle contained in rhizome of Curcuma longa, has been mentioned to show merit for diabetes through its anti-oxidative and anti-inflammatory properties. In the present study, we found that curcumin caused a concentration-dependent increase of glucose uptake into skeletal muscle isolated from Wistar rats. This action was inhibited by pirenzepine at concentration enough to block muscarinic M-1 cholinoceptor (M(1)-mAChR). In radioligand binding assay, the binding of [(3)H]-pirenzepine was also displaced by curcumin in a concentration-dependent manner. In the presence of inhibitors for PLC-PI3K pathway, either U73122 (phospholipase C inhibitor) or LY294002 (phosphoinositide 3-kinase inhibitor), curcumin-stimulated glucose uptake into skeletal muscle was markedly reduced. In Western blotting analysis, the membrane protein level of glucose transporter 4 (GLUT4) increased by curcumin was also reversed by blockade of M(1)-mAChR or PLC-PI3K pathway in a same manner. In conclusion, the obtained results suggest that curcumin can activate M(1)-mAChR at concentrations lower than to scavenge free radicals for increase of glucose uptake into skeletal muscle through PLC-PI3-kinase pathway.

  7. AMP-activated protein kinase in contraction regulation of skeletal muscle metabolism: necessary and/or sufficient?

    DEFF Research Database (Denmark)

    Jensen, Thomas Elbenhardt; Wojtaszewski, Jørgen; Richter, Erik

    2009-01-01

    In skeletal muscle, the contraction-activated heterotrimeric 5'-AMP-activated protein kinase (AMPK) protein is proposed to regulate the balance between anabolic and catabolic processes by increasing substrate uptake and turnover in addition to regulating the transcription of proteins involved...... in mitochondrial biogenesis and other aspects of promoting an oxidative muscle phenotype. Here, the current knowledge on the expression of AMPK subunits in human quadriceps muscle and evidence from rodent studies suggesting distinct AMPK subunit expression pattern in different muscle types is reviewed. Then......, the intensity and time dependence of AMPK activation in human quadriceps and rodent muscle are evaluated. Subsequently, a major part of this review critically examines the evidence supporting a necessary and/or sufficient role of AMPK in a broad spectrum of skeletal muscle contraction-relevant processes...

  8. Effects of hypothyroidism on the skeletal muscle blood flow response to contractions.

    Science.gov (United States)

    Bausch, L; McAllister, R M

    2003-04-01

    Hypothyroidism is associated with impaired blood flow to skeletal muscle under whole body exercise conditions. It is unclear whether poor cardiac and/or vascular function account for blunted muscle blood flow. Our experiment isolated a small group of hindlimb muscles and simulated exercise via tetanic contractions. We hypothesized that muscle blood flow would be attenuated in hypothyroid rats (HYPO) compared with euthyroid rats (EUT). Rats were made hypothyroid by mixing propylthiouracil in their drinking water (2.35 x 10-3 mol/l). Treatment efficacy was evidenced by lower serum T3 concentrations and resting heart rates in HYPO (both Pmuscles at a rate of 30 tetani/min were induced via sciatic nerve stimulation. Regional blood flows were determined by the radiolabelled microsphere method at three time points: rest, 2 min of contractions and 10 min of contractions. Muscle blood flow generally increased from rest ( approximately 5-10 ml/min per 100 g) through contractions for both groups. Further, blood flow during contractions did not differ between groups for any muscle (eg. red section of gastrocnemius muscle; EUT, 59.9 +/- 14.1; HYPO, 61.1 +/- 15.0; NS between groups). These findings indicate that hypothyroidism does not significantly impair skeletal muscle blood flow when only a small muscle mass is contracting. Our findings suggest that impaired blood flow under whole body exercise is accounted for by inadequate cardiac function rather than abnormal vascular function.

  9. Muscle Bioenergetic Considerations for Intrinsic Laryngeal Skeletal Muscle Physiology

    Science.gov (United States)

    Sandage, Mary J.; Smith, Audrey G.

    2017-01-01

    Purpose: Intrinsic laryngeal skeletal muscle bioenergetics, the means by which muscles produce fuel for muscle metabolism, is an understudied aspect of laryngeal physiology with direct implications for voice habilitation and rehabilitation. The purpose of this review is to describe bioenergetic pathways identified in limb skeletal muscle and…

  10. Contraction induced secretion of VEGF from skeletal muscle cells is mediated by adenosine

    DEFF Research Database (Denmark)

    Høier, Birgitte; Olsen, Karina; Nyberg, Michael Permin

    2010-01-01

    and that the contraction induced secretion of VEGF is partially mediated via adenosine acting on A(2B) adenosine receptors. Moreover, the contraction induced secretion of VEGF protein from muscle is dependent on both PKA and MAPK activation, but only the MAPK pathway appears to be adenosine dependent.......The role of adenosine and contraction for secretion of VEGF in skeletal muscle was investigated in human subjects and rat primary skeletal muscle cells. Microdialysis probes were inserted into the thigh muscle of seven male subjects and dialysate was collected at rest, during infusion of adenosine...... and contraction caused secretion of VEGF (pcontraction induced secretion of VEGF protein was abolished by the A(2B) antagonist enprofyllin and markedly reduced by inhibition of PKA or MAPK. The results demonstrate that adenosine causes secretion of VEGF from human skeletal muscle cells...

  11. Effect of the bendiocarb on the ultrastructure of rabbit skeletal muscle

    Directory of Open Access Journals (Sweden)

    Katarína Holovská

    2017-01-01

    Full Text Available Bendiocarb belongs to the group of carbamate insecticides that inhibit acetylcholinesterase. In agriculture, it is used to control a variety of insects, therefore it is important to examine every potential aspect of its toxicology. The aim of this study was to observe the effect of bendiocarb on the ultrastructure of the skeletal muscle in rabbits. Rabbits in all experimental groups received capsules of bendiocarb (96% Bendiocarb, Bayer, Germany per os daily at a dose of 5 mg/kg body weight. Samples of skeletal muscles were collected on days 10 and 20. On day 10 of the experiment, muscle fibres were not affected consistently. The observed changes were moderate and focal. Electron microscopy revealed dilatation of sarcoplasmic reticulum, and myofilament disorganization. On day 20 of the experiment, the ultrastructural changes in muscle fibres were more intense and more frequent. The most important alteration was the disruption of the sarcomeres due to the lysis of both thick and thin myofilaments. However, in the unchanged regions of muscle fibres a prominent mitochondrial swelling was observed. Many mitochondria lacked cristae and thus appeared as large membrane-bound cytoplasmic vesicles. The results presented in this study indicate that bendiocarb affects the ultrastructure of skeletal muscles. The intensity of damage (dissolution of myofilaments and disruption of sarcomeres was related to the duration of administration of bendiocarb.

  12. Skeletal muscle tissue engineering: methods to form skeletal myotubes and their applications.

    Science.gov (United States)

    Ostrovidov, Serge; Hosseini, Vahid; Ahadian, Samad; Fujie, Toshinori; Parthiban, Selvakumar Prakash; Ramalingam, Murugan; Bae, Hojae; Kaji, Hirokazu; Khademhosseini, Ali

    2014-10-01

    Skeletal muscle tissue engineering (SMTE) aims to repair or regenerate defective skeletal muscle tissue lost by traumatic injury, tumor ablation, or muscular disease. However, two decades after the introduction of SMTE, the engineering of functional skeletal muscle in the laboratory still remains a great challenge, and numerous techniques for growing functional muscle tissues are constantly being developed. This article reviews the recent findings regarding the methodology and various technical aspects of SMTE, including cell alignment and differentiation. We describe the structure and organization of muscle and discuss the methods for myoblast alignment cultured in vitro. To better understand muscle formation and to enhance the engineering of skeletal muscle, we also address the molecular basics of myogenesis and discuss different methods to induce myoblast differentiation into myotubes. We then provide an overview of different coculture systems involving skeletal muscle cells, and highlight major applications of engineered skeletal muscle tissues. Finally, potential challenges and future research directions for SMTE are outlined.

  13. Mitochondrial myopathies.

    Science.gov (United States)

    DiMauro, Salvatore

    2006-11-01

    Our understanding of mitochondrial diseases (defined restrictively as defects of the mitochondrial respiratory chain) is expanding rapidly. In this review, I will give the latest information on disorders affecting predominantly or exclusively skeletal muscle. The most recently described mitochondrial myopathies are due to defects in nuclear DNA, including coenzyme Q10 deficiency and mutations in genes controlling mitochondrial DNA abundance and structure, such as POLG, TK2, and MPV17. Barth syndrome, an X-linked recessive mitochondrial myopathy/cardiopathy, is associated with decreased amount and altered structure of cardiolipin, the main phospholipid of the inner mitochondrial membrane, but a secondary impairment of respiratory chain function is plausible. The role of mutations in protein-coding genes of mitochondrial DNA in causing isolated myopathies has been confirmed. Mutations in tRNA genes of mitochondrial DNA can also cause predominantly myopathic syndromes and--contrary to conventional wisdom--these mutations can be homoplasmic. Defects in the mitochondrial respiratory chain impair energy production and almost invariably involve skeletal muscle, causing exercise intolerance, cramps, recurrent myoglobinuria, or fixed weakness, which often affects extraocular muscles and results in droopy eyelids (ptosis) and progressive external ophthalmoplegia.

  14. Cell death induced by gamma irradiation of developing skeletal muscle

    International Nuclear Information System (INIS)

    Olive, M.; Blanco, R.; Rivera, R.; Cinos, C.; Ferrer, I.

    1995-01-01

    Newborn Sprague-Dawley rats were exposed to a single dose of 2 Gy gamma rays and killed from 6 h to 5 d later. Increased numbers of dying cells, characterised by their extreme chromatin condensation and often nuclear fragmentation were seen in skeletal muscle 6 h after irradiation. Dying cells decreased to nearly normal values 48 h later. In situ labelling of nuclear DNA fragmentation identified individual cells bearing fragmented DNA. The effects of gamma rays were suppressed following cycloheximide i.p. at a dose of 1 μg/g body weight given at the time of irradiation. Taken together, the present morphological and pharmacological results suggest that gamma ray induced cell death in skeletal muscle is apoptotic, and that the process is associated with protein synthesis. Finally, proliferating cell nuclear antigen-immunoreactive cells, which were abundant in control rats, decreased in number 48 h after irradiation. However, a marked increase significantly above normal age values was observed at the 5th day, thus suggesting that regeneration occurs following irradiation-induced cell death in developing muscle. (author)

  15. Developmental regulation of voltage-sensitive sodium channels in rat skeletal muscle

    International Nuclear Information System (INIS)

    Sherman, S.J.

    1985-01-01

    The developmental regulation of the voltage-sensitive Na + channel in rat skeletal muscle was studied in vivo and in vitro. In triceps surae muscle developing in vivo the development of TTX-sensitive Na + channel occurred primarily during the first three postnatal weeks as determined by the specific binding of [ 3 H]saxitoxin. This development proceeded in two separate phases. The first phase occurs independently of continuing motor neuron innervation and accounts for 60% of the adult density of TTX-sensitive Na + channels. The second phase, which begins about day 11, requires innervation. Muscle cells in primary culture were found to have both TTX-sensitive and insensitive Na + channels. The development of the TTX-sensitive channel, in vitro, paralleled the initial innervation-independent phase of development observed in vivo. The density of TTX-sensitive Na + channels in cultured muscle cells was regulated by electrical activity and cytosolic Ca ++ levels. Pharmacological blockade of the spontaneous electrical activity present in these cells lead to a nearly 2-fold increase in the surface density of TTX-sensitive channels. The turnover time of the TTX-sensitive Na + channel was measured by blocking the incorporation of newly synthesized channels with tunicamycin, an inhibitor of N-linked protein glycosylation. The regulation of channel density by electrical activity, cytosolic Ca ++ levels, and agents affecting cyclic neucleotide levels had no effect on the turnover time of the TTX-sensitive Na + channel, indicating that these regulatory agents instead affect the synthesis of the channel

  16. Muscle regeneration in mitochondrial myopathies

    DEFF Research Database (Denmark)

    Krag, T O; Hauerslev, S; Jeppesen, T D

    2013-01-01

    Mitochondrial myopathies cover a diverse group of disorders in which ragged red and COX-negative fibers are common findings on muscle morphology. In contrast, muscle degeneration and regeneration, typically found in muscular dystrophies, are not considered characteristic features of mitochondrial...... myopathies. We investigated regeneration in muscle biopsies from 61 genetically well-defined patients affected by mitochondrial myopathy. Our results show that the perturbed energy metabolism in mitochondrial myopathies causes ongoing muscle regeneration in a majority of patients, and some were even affected...

  17. Gene expression deregulation in postnatal skeletal muscle of TK2 deficient mice reveals a lower pool of proliferating myogenic progenitor cells.

    Directory of Open Access Journals (Sweden)

    João A Paredes

    Full Text Available Loss of thymidine kinase 2 (TK2 causes a heterogeneous myopathic form of mitochondrial DNA (mtDNA depletion syndrome (MDS in humans that predominantly affects skeletal muscle tissue. In mice, TK2 deficiency also affects several tissues in addition to skeletal muscle, including brain, heart, adipose tissue, kidneys and causes death about 3 weeks after birth. We analysed skeletal muscle and heart muscle tissues of Tk2 knockout mice at postnatal development phase and observed that TK2 deficient pups grew slower and their skeletal muscles appeared significantly underdeveloped, whereas heart was close to normal in size. Both tissues showed mtDNA depletion and mitochondria with altered ultrastructure, as revealed by transmission electron microscopy. Gene expression microarray analysis showed a strong down-regulation of genes involved in cell cycle and cell proliferation in both tissues, suggesting a lower pool of undifferentiated proliferating cells. Analysis of isolated primary myoblasts from Tk2 knockout mice showed slow proliferation, less ability to differentiate and signs of premature senescence, even in absence of mtDNA depletion. Our data demonstrate that TK2 deficiency disturbs myogenic progenitor cells function in postnatal skeletal muscle and we propose this as one of the causes of underdeveloped phenotype and myopathic characteristic of the TK2 deficient mice, in addition to the progressive mtDNA depletion, mitochondrial damage and respiratory chain deficiency in post-mitotic differentiated tissue.

  18. Gene expression deregulation in postnatal skeletal muscle of TK2 deficient mice reveals a lower pool of proliferating myogenic progenitor cells.

    Science.gov (United States)

    Paredes, João A; Zhou, Xiaoshan; Höglund, Stefan; Karlsson, Anna

    2013-01-01

    Loss of thymidine kinase 2 (TK2) causes a heterogeneous myopathic form of mitochondrial DNA (mtDNA) depletion syndrome (MDS) in humans that predominantly affects skeletal muscle tissue. In mice, TK2 deficiency also affects several tissues in addition to skeletal muscle, including brain, heart, adipose tissue, kidneys and causes death about 3 weeks after birth. We analysed skeletal muscle and heart muscle tissues of Tk2 knockout mice at postnatal development phase and observed that TK2 deficient pups grew slower and their skeletal muscles appeared significantly underdeveloped, whereas heart was close to normal in size. Both tissues showed mtDNA depletion and mitochondria with altered ultrastructure, as revealed by transmission electron microscopy. Gene expression microarray analysis showed a strong down-regulation of genes involved in cell cycle and cell proliferation in both tissues, suggesting a lower pool of undifferentiated proliferating cells. Analysis of isolated primary myoblasts from Tk2 knockout mice showed slow proliferation, less ability to differentiate and signs of premature senescence, even in absence of mtDNA depletion. Our data demonstrate that TK2 deficiency disturbs myogenic progenitor cells function in postnatal skeletal muscle and we propose this as one of the causes of underdeveloped phenotype and myopathic characteristic of the TK2 deficient mice, in addition to the progressive mtDNA depletion, mitochondrial damage and respiratory chain deficiency in post-mitotic differentiated tissue.

  19. Effect of exercise and obesity on skeletal muscle amino acid uptake

    International Nuclear Information System (INIS)

    Friedman, J.E.

    1988-01-01

    To determine if amino acid uptake by muscle of the obese Zucker rat is impaired, epitrochlearis (EPI) and soleus strip (SOL) muscles from 32 pairs of female lean (Fa/-) and obese (fa/fa) Zucker rats were incubated using [ 14 C]α-aminoisobutyric acid (AIB). Because contractile activity also influences amino acid uptake, the effect of acute endurance exercise on amino acid uptake by skeletal muscle from lean and obese rats was also studied. Muscle wet and dry weights were similar in lean and obese rats. However, both muscle protein content and concentration from obese rats were significantly reduced. In preliminary studies, pinning EPI at resting length during incubation significantly increased AIB uptake and reduced muscle water accumulation. AIB uptake was similar in stripped and intact SOL. Lean and obese rats were studied at rest or following a 1 hr treadmill run at 8% grade Muscles were pinned, and preincubated for 30 min at 37 degree C in Krebs Ringer bicarbonate buffer (KRB) containing 5mM glucose under 95:5 O 2 /CO 2 , followed by 30, 60, 120, or 180 min of incubation in KRB with 0.5 mM AIB, [ 14 C]-AIB to measure amino acid, and [ 3 H]-inulin to determine extracellular water

  20. [THE CHANGES OF NOCICEPTIVE THRESHOLD AND ACTIVITY OF THE ADENYLYL CYCLASE SYSTEM IN THE SKELETAL MUSCLES OF RATS WITH ACUTE AND MILD TYPE 1 DIABETES MELLITUS ].

    Science.gov (United States)

    Shipilov, V N; Trost, A M; Chistyakova, O V; Derkach, K V; Shpakov, A O

    2016-02-01

    Diabetic peripheral neuropathy (DPN) is one of the most common complications of the type 1 diabetes mellitus (DM1). The aim of the work was to study the dynamics of a painful DPN and functional state of the hormone-sensitive ACSS in the skeletal muscles of rats with the models of acute and mild DM1, as well as the study of impact on them of insulin therapy with different ways of hormone delivery - intranasal and peripheral. In both models of DM1, the level of nociceptive threshold in rats decreased and the stimulatory effects of guanine nucleotides (GppNHp) and adrenergic agonists (isoproterenol, BRL-37344) on adenylyl cyclase (AC) activity were attenuated. The AC stimulating effect of relaxin decreased in animals with acute DM1, but in mild DM1, the decrease was insignificant. Peripheral administration of insulin in rats with acute DM1 increased the nociceptive threshold and partially restored the AC effect of ß 3-agonist BRL-37344. Intranasal administration of insulin in rats with DM1 also increased the nociceptive threshold and partially restored the basal and BRL-37344-stimulated AC activity in the skeletal muscles of diabetic animals. Thus, in the skeletal muscles of rats with acute and mild DM1 the nociceptive sensitivity and the functions of ACSS were disturbed, and they were partially restored by the treatment with peripheral (acute DM1) or intranasal (mild DM1) insulin.

  1. Muscle mitochondrial metabolism and calcium signaling impairment in patients treated with statins

    Energy Technology Data Exchange (ETDEWEB)

    Sirvent, P., E-mail: pascal.sirvent@univ-bpclermont.fr [U1046, INSERM, Université Montpellier 1 and Université Montpellier 2, 34295 Montpellier (France); CHRU Montpellier, 34295 Montpellier (France); Clermont Université, Université Blaise Pascal, EA 3533, Laboratoire des Adaptations Métaboliques à l' Exercice en conditions Physiologiques et Pathologiques (AME2P), BP 80026, F-63171 Aubière cedex (France); Fabre, O.; Bordenave, S. [U1046, INSERM, Université Montpellier 1 and Université Montpellier 2, 34295 Montpellier (France); CHRU Montpellier, 34295 Montpellier (France); Hillaire-Buys, D. [CHRU Montpellier, 34295 Montpellier (France); Raynaud De Mauverger, E.; Lacampagne, A.; Mercier, J. [U1046, INSERM, Université Montpellier 1 and Université Montpellier 2, 34295 Montpellier (France); CHRU Montpellier, 34295 Montpellier (France)

    2012-03-01

    The most common and problematic side effect of statins is myopathy. To date, the patho-physiological mechanisms of statin myotoxicity are still not clearly understood. In previous studies, we showed that acute application in vitro of simvastatin caused impairment of mitochondrial function and dysfunction of calcium homeostasis in human and rat healthy muscle samples. We thus evaluated in the present study, mitochondrial function and calcium signaling in muscles of patients treated with statins, who present or not muscle symptoms, by oxygraphy and recording of calcium sparks, respectively. Patients treated with statins showed impairment of mitochondrial respiration that involved mainly the complex I of the respiratory chain and altered frequency and amplitude of calcium sparks. The muscle problems observed in statin-treated patients appear thus to be related to impairment of mitochondrial function and muscle calcium homeostasis, confirming the results we previously reported in vitro. -- Highlights: ► The most common and problematic side effect of statins is myopathy. ► Patients treated with statins showed impairment of mitochondrial respiration. ► Statins-treated patients showed altered frequency and amplitude of calcium sparks.

  2. Muscle mitochondrial metabolism and calcium signaling impairment in patients treated with statins

    International Nuclear Information System (INIS)

    Sirvent, P.; Fabre, O.; Bordenave, S.; Hillaire-Buys, D.; Raynaud De Mauverger, E.; Lacampagne, A.; Mercier, J.

    2012-01-01

    The most common and problematic side effect of statins is myopathy. To date, the patho-physiological mechanisms of statin myotoxicity are still not clearly understood. In previous studies, we showed that acute application in vitro of simvastatin caused impairment of mitochondrial function and dysfunction of calcium homeostasis in human and rat healthy muscle samples. We thus evaluated in the present study, mitochondrial function and calcium signaling in muscles of patients treated with statins, who present or not muscle symptoms, by oxygraphy and recording of calcium sparks, respectively. Patients treated with statins showed impairment of mitochondrial respiration that involved mainly the complex I of the respiratory chain and altered frequency and amplitude of calcium sparks. The muscle problems observed in statin-treated patients appear thus to be related to impairment of mitochondrial function and muscle calcium homeostasis, confirming the results we previously reported in vitro. -- Highlights: ► The most common and problematic side effect of statins is myopathy. ► Patients treated with statins showed impairment of mitochondrial respiration. ► Statins-treated patients showed altered frequency and amplitude of calcium sparks.

  3. Interdependence of AMPK and SIRT1 for metabolic adaptation to fasting and exercise in skeletal muscle

    DEFF Research Database (Denmark)

    Cantó, Carles; Jiang, Lake Q; Deshmukh, Atul S

    2010-01-01

    During fasting and after exercise, skeletal muscle efficiently switches from carbohydrate to lipid as the main energy source to preserve glycogen stores and blood glucose levels for glucose-dependent tissues. Skeletal muscle cells sense this limitation in glucose availability and transform...... and lipid utilization genes. Deficient AMPK activity compromises SIRT1-dependent responses to exercise and fasting, resulting in impaired PGC-1alpha deacetylation and blunted induction of mitochondrial gene expression. Thus, we conclude that AMPK acts as the primordial trigger for fasting- and exercise...

  4. Caffeine and contraction synergistically stimulate 5'-AMP-activated protein kinase and insulin-independent glucose transport in rat skeletal muscle.

    Science.gov (United States)

    Tsuda, Satoshi; Egawa, Tatsuro; Kitani, Kazuto; Oshima, Rieko; Ma, Xiao; Hayashi, Tatsuya

    2015-10-01

    5'-Adenosine monophosphate-activated protein kinase (AMPK) has been identified as a key mediator of contraction-stimulated insulin-independent glucose transport in skeletal muscle. Caffeine acutely stimulates AMPK in resting skeletal muscle, but it is unknown whether caffeine affects AMPK in contracting muscle. Isolated rat epitrochlearis muscle was preincubated and then incubated in the absence or presence of 3 mmol/L caffeine for 30 or 120 min. Electrical stimulation (ES) was used to evoke tetanic contractions during the last 10 min of the incubation period. The combination of caffeine plus contraction had additive effects on AMPKα Thr(172) phosphorylation, α-isoform-specific AMPK activity, and 3-O-methylglucose (3MG) transport. In contrast, caffeine inhibited basal and contraction-stimulated Akt Ser(473) phosphorylation. Caffeine significantly delayed muscle fatigue during contraction, and the combination of caffeine and contraction additively decreased ATP and phosphocreatine contents. Caffeine did not affect resting tension. Next, rats were given an intraperitoneal injection of caffeine (60 mg/kg body weight) or saline, and the extensor digitorum longus muscle was dissected 15 min later. ES of the sciatic nerve was performed to evoke tetanic contractions for 5 min before dissection. Similar to the findings from isolated muscles incubated in vitro, the combination of caffeine plus contraction in vivo had additive effects on AMPK phosphorylation, AMPK activity, and 3MG transport. Caffeine also inhibited basal and contraction-stimulated Akt phosphorylation in vivo. These findings suggest that caffeine and contraction synergistically stimulate AMPK activity and insulin-independent glucose transport, at least in part by decreasing muscle fatigue and thereby promoting energy consumption during contraction. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological

  5. High-fat feeding inhibits exercise-induced increase in mitochondrial respiratory flux in skeletal muscle

    DEFF Research Database (Denmark)

    Skovbro, Mette; Boushel, Robert Christopher; Hansen, Christina Neigaard

    2011-01-01

    ) and intramyocellular triacylglycerol content did not change with the intervention in either group. Indexes of mitochondrial density were similar across the groups and intervention. Mitochondrial respiratory rates, measured in permeabilized muscle fibers, showed a 31 ± 11 and 26 ± 9% exercise-induced increase (P

  6. Regulatory circuitry of TWEAK-Fn14 system and PGC-1α in skeletal muscle atrophy program.

    Science.gov (United States)

    Hindi, Sajedah M; Mishra, Vivek; Bhatnagar, Shephali; Tajrishi, Marjan M; Ogura, Yuji; Yan, Zhen; Burkly, Linda C; Zheng, Timothy S; Kumar, Ashok

    2014-03-01

    Skeletal muscle wasting attributed to inactivity has significant adverse functional consequences. Accumulating evidence suggests that peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) and TNF-like weak inducer of apoptosis (TWEAK)-Fn14 system are key regulators of skeletal muscle mass in various catabolic states. While the activation of TWEAK-Fn14 signaling causes muscle wasting, PGC-1α preserves muscle mass in several conditions, including functional denervation and aging. However, it remains unknown whether there is any regulatory interaction between PGC-1α and TWEAK-Fn14 system during muscle atrophy. Here we demonstrate that TWEAK significantly reduces the levels of PGC-1α and mitochondrial content (∼50%) in skeletal muscle. Levels of PGC-1α are significantly increased in skeletal muscle of TWEAK-knockout (KO) and Fn14-KO mice compared to wild-type mice on denervation. Transgenic (Tg) overexpression of PGC-1α inhibited progressive muscle wasting in TWEAK-Tg mice. PGC-1α inhibited the TWEAK-induced activation of NF-κB (∼50%) and dramatically reduced (∼90%) the expression of atrogenes such as MAFbx and MuRF1. Intriguingly, muscle-specific overexpression of PGC-1α also prevented the inducible expression of Fn14 in denervated skeletal muscle. Collectively, our study demonstrates that TWEAK induces muscle atrophy through repressing the levels of PGC-1α. Overexpression of PGC-1α not only blocks the TWEAK-induced atrophy program but also diminishes the expression of Fn14 in denervated skeletal muscle.

  7. The effect of caffeine on skeletal muscle anabolic signaling and hypertrophy.

    Science.gov (United States)

    Moore, Timothy M; Mortensen, Xavier M; Ashby, Conrad K; Harris, Alexander M; Kump, Karson J; Laird, David W; Adams, Aaron J; Bray, Jeremy K; Chen, Ting; Thomson, David M

    2017-06-01

    Caffeine is a widely consumed stimulant with the potential to enhance physical performance through multiple mechanisms. However, recent in vitro findings have suggested that caffeine may block skeletal muscle anabolic signaling through AMP-activated protein kinase (AMPK)-mediated inhibition of mechanistic target of rapamycin (mTOR) signaling pathway. This could negatively affect protein synthesis and the capacity for muscle growth. The primary purpose of this study was to assess the effect of caffeine on in vivo AMPK and mTOR pathway signaling, protein synthesis, and muscle growth. In cultured C2C12 muscle cells, physiological levels of caffeine failed to impact mTOR activation or myoblast proliferation or differentiation. We found that caffeine administration to mice did not significantly enhance the phosphorylation of AMPK or inhibit signaling proteins downstream of mTOR (p70S6k, S6, or 4EBP1) or protein synthesis after a bout of electrically stimulated contractions. Skeletal muscle-specific knockout of LKB1, the primary AMPK activator in skeletal muscle, on the other hand, eliminated AMPK activation by contractions and enhanced S6k, S6, and 4EBP1 activation before and after contractions. In rats, the addition of caffeine did not affect plantaris hypertrophy induced by the tenotomy of the gastrocnemius and soleus muscles. In conclusion, caffeine administration does not impair skeletal muscle load-induced mTOR signaling, protein synthesis, or muscle hypertrophy.

  8. A novel paradigm links mitochondrial dysfunction with muscle stem cell impairment in sepsis.

    Science.gov (United States)

    Chatre, Laurent; Verdonk, Franck; Rocheteau, Pierre; Crochemore, Clément; Chrétien, Fabrice; Ricchetti, Miria

    2017-10-01

    Sepsis is an acute systemic inflammatory response of the body to microbial infection and a life threatening condition associated with multiple organ failure. Survivors may display long-term disability with muscle weakness that remains poorly understood. Recent data suggest that long-term myopathy in sepsis survivors is due to failure of skeletal muscle stem cells (satellite cells) to regenerate the muscle. Satellite cells impairment in the acute phase of sepsis is linked to unusual mitochondrial dysfunctions, characterized by a dramatic reduction of the mitochondrial mass and hyperactivity of residual organelles. Survivors maintain the impairment of satellite cells, including alterations of the mitochondrial DNA (mtDNA), in the long-term. This condition can be rescued by treatment with mesenchymal stem cells (MSCs) that restore mtDNA alterations and mitochondrial function in satellite cells, and in fine their regenerative potential. Injection of MSCs in turn increases the force of isolated muscle fibers and of the whole animal, and improves the survival rate. These effects occur in the context of reduced inflammation markers that also raised during sepsis. Targeting muscle stem cells mitochondria, in a context of reduced inflammation, may represent a valuable strategy to reduce morbidity and long-term impairment of the muscle upon sepsis. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. [Relationship between PMI and fourier transform infrared spectral changes in muscle of rats after death caused by mechanical asphyxial].

    Science.gov (United States)

    Li, Shi-ying; Shao, Yu; Li, Zheng-dong; Liu, Ning-guo; Zou, Dong-hua; Qin, Zhi-qiang; Chen, Yi-jiu; Huang, Ping

    2012-06-01

    To observe the postmortem degradation process in rat myocardium and skeletal muscle using Fourier transform infrared (FTIR) spectroscopy and to provide a new method for estimating postmortem interval (PMI). Left ventricle and skeletal muscles of rats dying of mechanical asphyxiated were sampled at different PMIs. The changes of different chemical functional group in the myocardium and skeletal muscle samples were measured by FTIR spectroscopy. The different absorbance (A) ratios of peaks were calculated and the curve estimation analysis between absorbance ratios (x) and PMI (y) were performed to establish six mathematical models. FTIR spectral absorption peak of rat myocardium and skeletal muscle showed three changes: increase, decrease and stable. The cubic model function showed the strongest correlation coefficient. The A1080/A1396 ratio of skeletal muscle showed the strongest correlation coefficient (r = 0.832) with more accurate determination of PMI. FYIR spectroscopy can be potentially used as an effective method for estimating PMI in forensic practice using myocardium and skeletal muscle.

  10. Inhibition of skeletal muscle protein synthesis in septic intra-abdominal abscess

    International Nuclear Information System (INIS)

    Vary, T.C.; Siegel, J.H.; Tall, B.D.; Morris, J.G.; Smith, J.A.

    1988-01-01

    Chronic sepsis is always associated with profound wasting leading to increased release of amino acids from skeletal muscle. Net protein catabolism may be due to decreased rate of synthesis, increased rate of degradation, or both. To determine whether protein synthesis is altered in chronic sepsis, the rate of protein synthesis in vivo was estimated by measuring the incorporation of [ 3 H]-phenylalanine in skeletal muscle protein in a chronic (5-day) septic rat model induced by creation of a stable intra-abdominal abscess using an E. coli + B. fragilis-infected sterile fecal-agar pellet as foreign body nidus. Septic rats failed to gain weight at rates similar to control animals, therefore control animals were weight matched to the septic animals. The skeletal muscle protein content in septic animals was significantly reduced relative to control animals (0.18 +/- 0.01 vs. 0.21 +/- 0.01 mg protein/gm wet wt; p less than 0.02). The rate of incorporation of [ 3 H]-phenylalanine into skeletal muscle protein from control animals was 39 +/- 4 nmole/gm wet wt/hr or a fractional synthetic rate of 5.2 +/- 0.5%/day. In contrast to control animals, the fractional synthetic rate in septic animals (2.6 +/- 0.2%/day) was reduced by 50% compared to control animals (p less than 0.005). The decreased rate of protein synthesis in sepsis was not due to an energy deficit, as high-energy phosphates and ATP/ADP ratio were not altered. This decrease in protein synthesis occurred even though septic animals consumed as much food as control animals

  11. Caffeine and contraction synergistically stimulate 5′-AMP-activated protein kinase and insulin-independent glucose transport in rat skeletal muscle

    Science.gov (United States)

    Tsuda, Satoshi; Egawa, Tatsuro; Kitani, Kazuto; Oshima, Rieko; Ma, Xiao; Hayashi, Tatsuya

    2015-01-01

    5′-Adenosine monophosphate-activated protein kinase (AMPK) has been identified as a key mediator of contraction-stimulated insulin-independent glucose transport in skeletal muscle. Caffeine acutely stimulates AMPK in resting skeletal muscle, but it is unknown whether caffeine affects AMPK in contracting muscle. Isolated rat epitrochlearis muscle was preincubated and then incubated in the absence or presence of 3 mmol/L caffeine for 30 or 120 min. Electrical stimulation (ES) was used to evoke tetanic contractions during the last 10 min of the incubation period. The combination of caffeine plus contraction had additive effects on AMPKα Thr172 phosphorylation, α-isoform-specific AMPK activity, and 3-O-methylglucose (3MG) transport. In contrast, caffeine inhibited basal and contraction-stimulated Akt Ser473 phosphorylation. Caffeine significantly delayed muscle fatigue during contraction, and the combination of caffeine and contraction additively decreased ATP and phosphocreatine contents. Caffeine did not affect resting tension. Next, rats were given an intraperitoneal injection of caffeine (60 mg/kg body weight) or saline, and the extensor digitorum longus muscle was dissected 15 min later. ES of the sciatic nerve was performed to evoke tetanic contractions for 5 min before dissection. Similar to the findings from isolated muscles incubated in vitro, the combination of caffeine plus contraction in vivo had additive effects on AMPK phosphorylation, AMPK activity, and 3MG transport. Caffeine also inhibited basal and contraction-stimulated Akt phosphorylation in vivo. These findings suggest that caffeine and contraction synergistically stimulate AMPK activity and insulin-independent glucose transport, at least in part by decreasing muscle fatigue and thereby promoting energy consumption during contraction. PMID:26471759

  12. Antioxidant Supplement Inhibits Skeletal Muscle Constitutive Autophagy rather than Fasting-Induced Autophagy in Mice

    Directory of Open Access Journals (Sweden)

    Zhengtang Qi

    2014-01-01

    Full Text Available In this study, we tested the hypothesis that NAC administration leads to reduced oxidative stress and thus to decreased expression of autophagy markers in young mice. Our results reveal that NAC administration results in reduced muscle mRNA levels of several autophagy markers, including Beclin-1, Atg7, LC3, Atg9, and LAMP2. However, NAC supplement fails to block the activation of skeletal muscle autophagy in response to fasting, because fasting significantly increases the mRNA level of several autophagy markers and LC3 lipidation. We further examined the effects of NAC administration on mitochondrial antioxidant capacity in fed and 24-hour fasted mice. Our results clearly show that NAC administration depresses the expression of manganese superoxide dismutase (MnSOD and TP53-induced glycolysis and apoptosis regulator (TIGAR, both of which play a predominant antioxidant role in mitochondria by reducing ROS level. In addition, we found no beneficial effect of NAC supplement on muscle mass but it can protect from muscle loss in response to fasting. Collectively, our findings indicate that ROS is required for skeletal muscle constitutive autophagy, rather than starvation-induced autophagy, and that antioxidant NAC inhibits constitutive autophagy by the regulation of mitochondrial ROS production and antioxidant capacity.

  13. Skeletal muscle and fetal alcohol spectrum disorder.

    Science.gov (United States)

    Myrie, Semone B; Pinder, Mark A

    2018-04-01

    Skeletal muscle is critical for mobility and many metabolic functions integral to survival and long-term health. Alcohol can affect skeletal muscle physiology and metabolism, which will have immediate and long-term consequences on health. While skeletal muscle abnormalities, including morphological, biochemical, and functional impairments, are well-documented in adults that excessively consume alcohol, there is a scarcity of information about the skeletal muscle in the offspring prenatally exposed to alcohol ("prenatal alcohol exposure"; PAE). This minireview examines the available studies addressing skeletal muscle abnormalities due to PAE. Growth restriction, fetal alcohol myopathy, and abnormalities in the neuromuscular system, which contribute to deficits in locomotion, are some direct, immediate consequences of PAE on skeletal muscle morphology and function. Long-term health consequences of PAE-related skeletal abnormalities include impaired glucose metabolism in the skeletal muscle, resulting in glucose intolerance and insulin resistance, leading to an increased risk of type 2 diabetes. In general, there is limited information on the morphological, biochemical, and functional features of skeletal abnormalities in PAE offspring. There is a need to understand how PAE affects muscle growth and function at the cellular level during early development to improve the immediate and long-term health of offspring suffering from PAE.

  14. Relationship between serum IGF-1 and skeletal muscle IGF-1 mRNA expression to phosphocreatine recovery after exercise in obese men with reduced GH.

    Science.gov (United States)

    Hamarneh, Sulaiman R; Murphy, Caitlin A; Shih, Cynthia W; Frontera, Walter; Torriani, Martin; Irazoqui, Javier E; Makimura, Hideo

    2015-02-01

    GH and IGF-1 are believed to be physiological regulators of skeletal muscle mitochondria. The objective of this study was to examine the relationship between GH/IGF-1 and skeletal muscle mitochondria in obese subjects with reduced GH secretion in more detail. Fifteen abdominally obese men with reduced GH secretion were treated for 12 weeks with recombinant human GH. Subjects underwent (31)P-magnetic resonance spectroscopy to assess phosphocreatine (PCr) recovery as an in vivo measure of skeletal muscle mitochondrial function and percutaneous muscle biopsies to assess mRNA expression of IGF-1 and mitochondrial-related genes at baseline and 12 weeks. At baseline, skeletal muscle IGF-1 mRNA expression was significantly associated with PCr recovery (r = 0.79; P = .01) and nuclear respiratory factor-1 (r = 0.87; P = .001), mitochondrial transcription factor A (r = 0.86; P = .001), peroxisome proliferator-activated receptor (PPAR)γ (r = 0.72; P = .02), and PPARα (r = 0.75; P = .01) mRNA expression, and trended to an association with PPARγ coactivator 1-α (r = 0.59; P = .07) mRNA expression. However, serum IGF-1 concentration was not associated with PCr recovery or any mitochondrial gene expression (all P > .10). Administration of recombinant human GH increased both serum IGF-1 (change, 218 ± 29 μg/L; P IGF-1 mRNA in muscle (fold change, 2.1 ± 0.3; P = .002). Increases in serum IGF-1 were associated with improvements in total body fat (r = -0.53; P = .04), trunk fat (r = -0.55; P = .03), and lean mass (r = 0.58; P = .02), but not with PCr recovery (P > .10). Conversely, increase in muscle IGF-1 mRNA was associated with improvements in PCr recovery (r = 0.74; P = .02), but not with body composition parameters (P > .10). These data demonstrate a novel association of skeletal muscle mitochondria with muscle IGF-1 mRNA expression, but independent of serum IGF-1 concentrations.

  15. Apoptosis-inducing effect of selective sensory or motor nerve injury on skeletal muscle atrophy

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    Lei ZHAO

    2011-09-01

    Full Text Available Objective To explore the apoptosis-inducing effect of selective sensory or motor nerve injury on skeletal muscle atrophy.Methods Thirty healthy adult SD rats were randomly divided into three groups,namely,ventral root transection group(VRT group,received left L4-L6 ventral rhizotomy,dorsal root transection group(DRT group,received left L4-L6 dorsal rhizotomy,and sciatic nerve transection group(SNT group,received left sciatic nerve transection.Each group comprised 10 SD rats.The bilateral gastrocnemius was harvested 10 weeks after operation to observe the apoptosis and Fas/FasL expression of the skeletal muscle cells through fluorescent labeling,transmission electron microscopy,and immunohistochemistry.Result Ten weeks after the denervation,apoptosis-related changes,especially obvious changes of the nuclear apoptotic morphology,were observed in the skeletal muscle cells.The aggregation degree of the nucleus and the expression of Fas/FasL increased in the following order: DRT group,VRT group,and SNT group.No apoptotic body,but early apoptotic morphology,was found in the denervated gastrocnemius through transmission electron microscopy.Conclusions The effect of motor nerve injury on skeletal muscle atrophy is more serious than that of sensory nerve injury.The rebuilding of motor nerves should be preferentially considered in the clinical treatment of muscle atrophy induced by denervation.

  16. Human skeletal muscle releases leptin in vivo

    DEFF Research Database (Denmark)

    Wolsk, Emil; Grøndahl, Thomas Sahl; Pedersen, Bente Klarlund

    2012-01-01

    Leptin is considered an adipokine, however, cultured myocytes have also been found to release leptin. Therefore, as proof-of-concept we investigated if human skeletal muscle synthesized leptin by measuring leptin in skeletal muscle biopsies. Following this, we quantified human skeletal muscle...... was unaltered. During saline infusion the adipose tissue release averaged 0.8 ± 0.3 ng min(-1) 100g tissue(-1) whereas skeletal muscle release was 0.5 ± 0.1 ng min(-1) 100g tissue(-1). In young healthy humans, skeletal muscle contribution to whole body leptin production could be substantial given the greater...

  17. High Intensity Interval Training (HIIT) Induces Specific Changes in Respiration and Electron Leakage in the Mitochondria of Different Rat Skeletal Muscles.

    Science.gov (United States)

    Ramos-Filho, Dionizio; Chicaybam, Gustavo; de-Souza-Ferreira, Eduardo; Guerra Martinez, Camila; Kurtenbach, Eleonora; Casimiro-Lopes, Gustavo; Galina, Antonio

    2015-01-01

    High intensity interval training (HIIT) is characterized by vigorous exercise with short rest intervals. Hydrogen peroxide (H2O2) plays a key role in muscle adaptation. This study aimed to evaluate whether HIIT promotes similar H2O2 formation via O2 consumption (electron leakage) in three skeletal muscles with different twitch characteristics. Rats were assigned to two groups: sedentary (n=10) and HIIT (n=10, swimming training). We collected the tibialis anterior (TA-fast), gastrocnemius (GAST-fast/slow) and soleus (SOL-slow) muscles. The fibers were analyzed for mitochondrial respiration, H2O2 production and citrate synthase (CS) activity. A multi-substrate (glycerol phosphate (G3P), pyruvate, malate, glutamate and succinate) approach was used to analyze the mitochondria in permeabilized fibers. Compared to the control group, oxygen flow coupled to ATP synthesis, complex I and complex II was higher in the TA of the HIIT group by 1.5-, 3.0- and 2.7-fold, respectively. In contrast, oxygen consumed by mitochondrial glycerol phosphate dehydrogenase (mGPdH) was 30% lower. Surprisingly, the oxygen flow coupled to ATP synthesis was 42% lower after HIIT in the SOL. Moreover, oxygen flow coupled to ATP synthesis and complex II was higher by 1.4- and 2.7-fold in the GAST of the HIIT group. After HIIT, CS activity increased 1.3-fold in the TA, and H2O2 production was 1.3-fold higher in the TA at sites containing mGPdH. No significant differences in H2O2 production were detected in the SOL. Surprisingly, HIIT increased H2O2 production in the GAST via complex II, phosphorylation, oligomycin and antimycin by 1.6-, 1.8-, 2.2-, and 2.2-fold, respectively. Electron leakage was 3.3-fold higher in the TA with G3P and 1.8-fold higher in the GAST with multiple substrates. Unexpectedly, the HIIT protocol induced different respiration and electron leakage responses in different types of muscle.

  18. High Intensity Interval Training (HIIT Induces Specific Changes in Respiration and Electron Leakage in the Mitochondria of Different Rat Skeletal Muscles.

    Directory of Open Access Journals (Sweden)

    Dionizio Ramos-Filho

    Full Text Available High intensity interval training (HIIT is characterized by vigorous exercise with short rest intervals. Hydrogen peroxide (H2O2 plays a key role in muscle adaptation. This study aimed to evaluate whether HIIT promotes similar H2O2 formation via O2 consumption (electron leakage in three skeletal muscles with different twitch characteristics. Rats were assigned to two groups: sedentary (n=10 and HIIT (n=10, swimming training. We collected the tibialis anterior (TA-fast, gastrocnemius (GAST-fast/slow and soleus (SOL-slow muscles. The fibers were analyzed for mitochondrial respiration, H2O2 production and citrate synthase (CS activity. A multi-substrate (glycerol phosphate (G3P, pyruvate, malate, glutamate and succinate approach was used to analyze the mitochondria in permeabilized fibers. Compared to the control group, oxygen flow coupled to ATP synthesis, complex I and complex II was higher in the TA of the HIIT group by 1.5-, 3.0- and 2.7-fold, respectively. In contrast, oxygen consumed by mitochondrial glycerol phosphate dehydrogenase (mGPdH was 30% lower. Surprisingly, the oxygen flow coupled to ATP synthesis was 42% lower after HIIT in the SOL. Moreover, oxygen flow coupled to ATP synthesis and complex II was higher by 1.4- and 2.7-fold in the GAST of the HIIT group. After HIIT, CS activity increased 1.3-fold in the TA, and H2O2 production was 1.3-fold higher in the TA at sites containing mGPdH. No significant differences in H2O2 production were detected in the SOL. Surprisingly, HIIT increased H2O2 production in the GAST via complex II, phosphorylation, oligomycin and antimycin by 1.6-, 1.8-, 2.2-, and 2.2-fold, respectively. Electron leakage was 3.3-fold higher in the TA with G3P and 1.8-fold higher in the GAST with multiple substrates. Unexpectedly, the HIIT protocol induced different respiration and electron leakage responses in different types of muscle.

  19. The effects of beta-adrenoceptor activation on contraction in isolated fast- and slow-twitch skeletal muscle fibres of the rat.

    OpenAIRE

    Cairns, S. P.; Dulhunty, A. F.

    1993-01-01

    1. The aim of the experiments was to examined the effects of beta-adrenoceptor activation on twitch and tetanic contractions in fast- and slow-twitch mammalian skeletal muscle fibres. Isometric force was recorded from bundles of intact fibres isolated from the normal and denervated slow-twitch soleus and normal fast-twitch sternomastoid muscles of the rat. 2. Terbutaline (10 microM), a beta 2-adrenoceptor agonist, induced an average 15% potentiation of peak twitch and peak tetanic force in no...

  20. Nur77 coordinately regulates expression of genes linked to glucose metabolism in skeletal muscle.

    Science.gov (United States)

    Chao, Lily C; Zhang, Zidong; Pei, Liming; Saito, Tsugumichi; Tontonoz, Peter; Pilch, Paul F

    2007-09-01

    Innervation is important for normal metabolism in skeletal muscle, including insulin-sensitive glucose uptake. However, the transcription factors that transduce signals from the neuromuscular junction to the nucleus and affect changes in metabolic gene expression are not well defined. We demonstrate here that the orphan nuclear receptor Nur77 is a regulator of gene expression linked to glucose utilization in muscle. In vivo, Nur77 is preferentially expressed in glycolytic compared with oxidative muscle and is responsive to beta-adrenergic stimulation. Denervation of rat muscle compromises expression of Nur77 in parallel with that of numerous genes linked to glucose metabolism, including glucose transporter 4 and genes involved in glycolysis, glycogenolysis, and the glycerophosphate shuttle. Ectopic expression of Nur77, either in rat muscle or in C2C12 muscle cells, induces expression of a highly overlapping set of genes, including glucose transporter 4, muscle phosphofructokinase, and glycogen phosphorylase. Furthermore, selective knockdown of Nur77 in rat muscle by small hairpin RNA or genetic deletion of Nur77 in mice reduces the expression of a battery of genes involved in skeletal muscle glucose utilization in vivo. Finally, we show that Nur77 binds the promoter regions of multiple genes involved in glucose metabolism in muscle. These results identify Nur77 as a potential mediator of neuromuscular signaling in the control of metabolic gene expression.

  1. Oral Supplementation of Melatonin Protects against Fibromyalgia-Related Skeletal Muscle Alterations in Reserpine-Induced Myalgia Rats.

    Science.gov (United States)

    Favero, Gaia; Trapletti, Valentina; Bonomini, Francesca; Stacchiotti, Alessandra; Lavazza, Antonio; Rodella, Luigi Fabrizio; Rezzani, Rita

    2017-06-29

    Fibromyalgia is a chronic syndrome characterized by widespread musculoskeletal pain and an extensive array of other symptoms including disordered sleep, fatigue, depression and anxiety. Important factors involved in the pathogenic process of fibromyalgia are inflammation and oxidative stress, suggesting that ant-inflammatory and/or antioxidant supplementation might be effective in the management and modulation of this syndrome. Recent evidence suggests that melatonin may be suitable for this purpose due to its well known ant-inflammatory, antioxidant and analgesic effects. Thus, in the current study, the effects of the oral supplementation of melatonin against fibromyalgia-related skeletal muscle alterations were evaluated. In detail, 90 Sprague Dawley rats were randomly treated with reserpine, to reproduce the pathogenic process of fibromyalgia and thereafter they received melatonin. The animals treated with reserpine showed moderate alterations at hind limb skeletal muscles level and had difficulty in moving, together with significant morphological and ultrastructural alterations and expression of inflammatory and oxidative stress markers in the gastrocnemius muscle. Interestingly, melatonin, dose and/or time dependently, reduced the difficulties in spontaneous motor activity and the musculoskeletal morphostructural, inflammatory, and oxidative stress alterations. This study suggests that melatonin in vivo may be an effective tool in the management of fibromyalgia-related musculoskeletal morphofunctional damage.

  2. Diclofenac pretreatment modulates exercise-induced inflammation in skeletal muscle of rats through the TLR4/NF-κB pathway.

    Science.gov (United States)

    Barcelos, Rômulo Pillon; Bresciani, Guilherme; Cuevas, Maria José; Martínez-Flórez, Susana; Soares, Félix Alexandre Antunes; González-Gallego, Javier

    2017-07-01

    Nonsteroidal anti-inflammatory drugs, such as diclofenac, are widely used to treat inflammation and pain in several conditions, including sports injuries. This study analyzes the influence of diclofenac on the toll-like receptor-nuclear factor kappa B (TLR-NF-κB) pathway in skeletal muscle of rats submitted to acute eccentric exercise. Twenty male Wistar rats were divided into 4 groups: control-saline, control-diclofenac, exercise-saline, and exercise-diclofenac. Diclofenac or saline were administered for 7 days prior to an acute eccentric exercise bout. The inflammatory status was evaluated through mRNA levels of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), interleukin-6 (IL-6), IL-1β, and tumor necrosis factor alpha (TNF-α), and protein content of COX-2, IL-6, and TNF-α in vastus lateralis muscle. Data obtained showed that a single bout of eccentric exercise significantly increased COX-2 gene expression. Similarly, mRNA expression and protein content of other inflammation-related genes also increased after the acute exercise. However, these effects were attenuated in the exercise + diclofenac group. TLR4, myeloid differentiation primary response gene 88 (MyD88), and p65 were also upregulated after the acute eccentric bout and the effect was blunted by the anti-inflammatory drug. These findings suggest that pretreatment with diclofenac may represent an effective tool to ameliorate the pro-inflammatory status induced by acute exercise in rat skeletal muscle possibly through an attenuation of the TLR4-NF-κB signaling pathway.

  3. Increased peripheral vascular disease risk progressively constrains perfusion adaptability in the skeletal muscle microcirculation

    Science.gov (United States)

    Butcher, Joshua T.; Frisbee, Stephanie J.; Olfert, I. Mark; Chantler, Paul D.; Tabone, Lawrence E.; d'Audiffret, Alexandre C.; Shrader, Carl D.; Goodwill, Adam G.; Stapleton, Phoebe A.; Brooks, Steven D.; Brock, Robert W.; Lombard, Julian H.

    2015-01-01

    To determine the impact of progressive elevations in peripheral vascular disease (PVD) risk on microvascular function, we utilized eight rat models spanning “healthy” to “high PVD risk” and used a multiscale approach to interrogate microvascular function and outcomes: healthy: Sprague-Dawley rats (SDR) and lean Zucker rats (LZR); mild risk: SDR on high-salt diet (HSD) and SDR on high-fructose diet (HFD); moderate risk: reduced renal mass-hypertensive rats (RRM) and spontaneously hypertensive rats (SHR); high risk: obese Zucker rats (OZR) and Dahl salt-sensitive rats (DSS). Vascular reactivity and biochemical analyses demonstrated that even mild elevations in PVD risk severely attenuated nitric oxide (NO) bioavailability and caused progressive shifts in arachidonic acid metabolism, increasing thromboxane A2 levels. With the introduction of hypertension, arteriolar myogenic activation and adrenergic constriction were increased. However, while functional hyperemia and fatigue resistance of in situ skeletal muscle were not impacted with mild or moderate PVD risk, blood oxygen handling suggested an increasingly heterogeneous perfusion within resting and contracting skeletal muscle. Analysis of in situ networks demonstrated an increasingly stable and heterogeneous distribution of perfusion at arteriolar bifurcations with elevated PVD risk, a phenomenon that was manifested first in the distal microcirculation and evolved proximally with increasing risk. The increased perfusion distribution heterogeneity and loss of flexibility throughout the microvascular network, the result of the combined effects on NO bioavailability, arachidonic acid metabolism, myogenic activation, and adrenergic constriction, may represent the most accurate predictor of the skeletal muscle microvasculopathy and poor health outcomes associated with chronic elevations in PVD risk. PMID:26702145

  4. Time course in calpain activity and autolysis in slow and fast skeletal muscle during clenbuterol treatment.

    Science.gov (United States)

    Douillard, Aymeric; Galbes, Olivier; Rossano, Bernadette; Vernus, Barbara; Bonnieu, Anne; Candau, Robin; Py, Guillaume

    2011-02-01

    Calpains are Ca2+ cysteine proteases that have been proposed to be involved in the cytoskeletal remodeling and wasting of skeletal muscle. Cumulative evidence also suggests that β2-agonists can lead to skeletal muscle hypertrophy through a mechanism probably related to calcium-dependent proteolytic enzyme. The aim of our study was to monitor calpain activity as a function of clenbuterol treatment in both slow and fast phenotype rat muscles. For this purpose, for 21 days we followed the time course of the calpain activity and of the ubiquitous calpain 1 and 2 autolysis, as well as muscle remodeling in the extensor digitorum longus (EDL) and soleus muscles of male Wistar rats treated daily with clenbuterol (4 mg·kg-1). A slow to fast fiber shift was observed in both the EDL and soleus muscles after 9 days of treatment, while hypertrophy was observed only in EDL after 9 days of treatment. Soleus muscle but not EDL muscle underwent an early apoptonecrosis phase characterized by hematoxylin and eosin staining. Total calpain activity was increased in both the EDL and soleus muscles of rats treated with clenbuterol. Moreover, calpain 1 autolysis increased significantly after 14 days in the EDL, but not in the soleus. Calpain 2 autolysis increased significantly in both muscles 6 hours after the first clenbuterol injection, indicating that clenbuterol-induced calpain 2 autolysis occurred earlier than calpain 1 autolysis. Together, these data suggest a preferential involvement of calpain 2 autolysis compared with calpain 1 autolysis in the mechanisms underlying the clenbuterol-induced skeletal muscle remodeling.

  5. Skeletal Muscle Metabolism in Duchenne and Becker Muscular Dystrophy—Implications for Therapies

    Directory of Open Access Journals (Sweden)

    Ahlke Heydemann

    2018-06-01

    Full Text Available The interactions between nutrition and metabolism and skeletal muscle have long been known. Muscle is the major metabolic organ—it consumes more calories than other organs—and therefore, there is a clear need to discuss these interactions and provide some direction for future research areas regarding muscle pathologies. In addition, new experiments and manuscripts continually reveal additional highly intricate, reciprocal interactions between metabolism and muscle. These reciprocal interactions include exercise, age, sex, diet, and pathologies including atrophy, hypoxia, obesity, diabetes, and muscle myopathies. Central to this review are the metabolic changes that occur in the skeletal muscle cells of muscular dystrophy patients and mouse models. Many of these metabolic changes are pathogenic (inappropriate body mass changes, mitochondrial dysfunction, reduced adenosine triphosphate (ATP levels, and increased Ca2+ and others are compensatory (increased phosphorylated AMP activated protein kinase (pAMPK, increased slow fiber numbers, and increased utrophin. Therefore, reversing or enhancing these changes with therapies will aid the patients. The multiple therapeutic targets to reverse or enhance the metabolic pathways will be discussed. Among the therapeutic targets are increasing pAMPK, utrophin, mitochondrial number and slow fiber characteristics, and inhibiting reactive oxygen species. Because new data reveals many additional intricate levels of interactions, new questions are rapidly arising. How does muscular dystrophy alter metabolism, and are the changes compensatory or pathogenic? How does metabolism affect muscular dystrophy? Of course, the most profound question is whether clinicians can therapeutically target nutrition and metabolism for muscular dystrophy patient benefit? Obtaining the answers to these questions will greatly aid patients with muscular dystrophy.

  6. Skeletal Muscle Metabolism in Duchenne and Becker Muscular Dystrophy-Implications for Therapies.

    Science.gov (United States)

    Heydemann, Ahlke

    2018-06-20

    The interactions between nutrition and metabolism and skeletal muscle have long been known. Muscle is the major metabolic organ—it consumes more calories than other organs—and therefore, there is a clear need to discuss these interactions and provide some direction for future research areas regarding muscle pathologies. In addition, new experiments and manuscripts continually reveal additional highly intricate, reciprocal interactions between metabolism and muscle. These reciprocal interactions include exercise, age, sex, diet, and pathologies including atrophy, hypoxia, obesity, diabetes, and muscle myopathies. Central to this review are the metabolic changes that occur in the skeletal muscle cells of muscular dystrophy patients and mouse models. Many of these metabolic changes are pathogenic (inappropriate body mass changes, mitochondrial dysfunction, reduced adenosine triphosphate (ATP) levels, and increased Ca 2+ ) and others are compensatory (increased phosphorylated AMP activated protein kinase (pAMPK), increased slow fiber numbers, and increased utrophin). Therefore, reversing or enhancing these changes with therapies will aid the patients. The multiple therapeutic targets to reverse or enhance the metabolic pathways will be discussed. Among the therapeutic targets are increasing pAMPK, utrophin, mitochondrial number and slow fiber characteristics, and inhibiting reactive oxygen species. Because new data reveals many additional intricate levels of interactions, new questions are rapidly arising. How does muscular dystrophy alter metabolism, and are the changes compensatory or pathogenic? How does metabolism affect muscular dystrophy? Of course, the most profound question is whether clinicians can therapeutically target nutrition and metabolism for muscular dystrophy patient benefit? Obtaining the answers to these questions will greatly aid patients with muscular dystrophy.

  7. Oral quercetin supplementation hampers skeletal muscle adaptations in response to exercise training

    DEFF Research Database (Denmark)

    Casuso, R A; Martínez-López, E J; Nordsborg, Nikolai Baastrup

    2014-01-01

    We aimed to test exercise-induced adaptations on skeletal muscle when quercetin is supplemented. Four groups of rats were tested: quercetin sedentary, quercetin exercised, placebo sedentary, and placebo exercised. Treadmill exercise training took place 5 days a week for 6 weeks. Quercetin groups ...... status was also quantified by measuring muscle antioxidant enzymatic activity and oxidative damage product, such as protein carbonyl content (PCC). Quercetin supplementation increased oxidative damage in both exercised and sedentary rats by inducing higher amounts of PCC (P ...

  8. Three dimensional reconstruction of the human skeletal muscle mitochondrial network as a tool to assess mitochondrial content and structural organization

    DEFF Research Database (Denmark)

    Dahl, Rannvá; Larsen, Steen; Dohlmann, Tine L

    2015-01-01

    a method to visualize mitochondrial networks in high resolution and assess mitochondrial volume. Methods: Confocal fluorescence microscopy imaging of mitochondrial network stains in human vastus lateralis single muscle fibers and, focused ion beam scanning electron microscopy (FIB/SEM) imaging, combined...... mitochondrial dynamics in response to life-style interventions and/or in certain pathologies. Our results question the classification of mitochondria into subsarcolemmal and intermyofibrillar pools, since they are physically interconnected. This article is protected by copyright. All rights reserved....

  9. Skeletal Muscle Na+ Channel Disorders

    Directory of Open Access Journals (Sweden)

    Dina eSimkin

    2011-10-01

    Full Text Available Five inherited human disorders affecting skeletal muscle contraction have been traced to mutations in the gene encoding the voltage-gated sodium channel Nav1.4. The main symptoms of these disorders are myotonia or periodic paralysis caused by changes in skeletal muscle fiber excitability. Symptoms of these disorders vary from mild or latent disease to incapacitating or even death in severe cases. As new human sodium channel mutations corresponding to disease states become discovered, the importance of understanding the role of the sodium channel in skeletal muscle function and disease state grows.

  10. Skeletal Muscle Insulin Resistance in Endocrine Disease

    Directory of Open Access Journals (Sweden)

    Melpomeni Peppa

    2010-01-01

    Full Text Available We summarize the existing literature data concerning the involvement of skeletal muscle (SM in whole body glucose homeostasis and the contribution of SM insulin resistance (IR to the metabolic derangements observed in several endocrine disorders, including polycystic ovary syndrome (PCOS, adrenal disorders and thyroid function abnormalities. IR in PCOS is associated with a unique postbinding defect in insulin receptor signaling in general and in SM in particular, due to a complex interaction between genetic and environmental factors. Adrenal hormone excess is also associated with disrupted insulin action in peripheral tissues, such as SM. Furthermore, both hyper- and hypothyroidism are thought to be insulin resistant states, due to insulin receptor and postreceptor defects. Further studies are definitely needed in order to unravel the underlying pathogenetic mechanisms. In summary, the principal mechanisms involved in muscle IR in the endocrine diseases reviewed herein include abnormal phosphorylation of insulin signaling proteins, altered muscle fiber composition, reduced transcapillary insulin delivery, decreased glycogen synthesis, and impaired mitochondrial oxidative metabolism.

  11. Regulation of skeletal muscle oxidative capacity and muscle mass by SIRT3.

    Directory of Open Access Journals (Sweden)

    Ligen Lin

    Full Text Available We have previously reported that the expression of mitochondrial deacetylase SIRT3 is high in the slow oxidative muscle and that the expression of muscle SIRT3 level is increased by dietary restriction or exercise training. To explore the function of SIRT3 in skeletal muscle, we report here the establishment of a transgenic mouse model with muscle-specific expression of the murine SIRT3 short isoform (SIRT3M3. Calorimetry study revealed that the transgenic mice had increased energy expenditure and lower respiratory exchange rate (RER, indicating a shift towards lipid oxidation for fuel usage, compared to control mice. The transgenic mice exhibited better exercise performance on treadmills, running 45% further than control animals. Moreover, the transgenic mice displayed higher proportion of slow oxidative muscle fibers, with increased muscle AMPK activation and PPARδ expression, both of which are known regulators promoting type I muscle fiber specification. Surprisingly, transgenic expression of SIRT3M3 reduced muscle mass up to 30%, likely through an up-regulation of FOXO1 transcription factor and its downstream atrophy gene MuRF-1. In summary, these results suggest that SIRT3 regulates the formation of oxidative muscle fiber, improves muscle metabolic function, and reduces muscle mass, changes that mimic the effects of caloric restriction.

  12. Adipophilin distribution and colocalization with lipid droplets in skeletal muscle.

    LENUS (Irish Health Repository)

    Shaw, Christopher S

    2009-05-01

    Intramyocellular lipids (IMCL) are stored as discrete lipid droplets which are associated with a number of proteins. The lipid droplet-associated protein adipophilin (the human orthologue of adipose differentiation-related protein) is ubiquitously expressed and is one of the predominant lipid droplet-proteins in skeletal muscle. The aim of this study was to investigate the subcellular distribution of adipophilin in human muscle fibres and to measure the colocalization of adipophilin with IMCL. Muscle biopsies from six lean male cyclists (BMI 23.4 +\\/- 0.4, aged 31 +\\/- 2 years, W (max) 346 +\\/- 8) were stained for myosin heavy chain type 1, IMCL, adipophilin and mitochondria using immunofluorescence and viewed with widefield and confocal fluorescence microscopy. The present study shows that like IMCL, the adipophilin content is ~twofold greater in type I skeletal muscle fibres and is situated in the areas between the mitochondrial network. Colocalization analysis demonstrated that 61 +\\/- 2% of IMCL contain adipophilin. Although the majority of adipophilin is contained within IMCL, 36 +\\/- 4% of adipophilin is not associated with IMCL. In conclusion, this study indicates that the IMCL pool is heterogeneous, as the majority but not all IMCL contain adipophilin.

  13. [Molecular mechanisms of skeletal muscle hypertrophy].

    Science.gov (United States)

    Astratenkova, I V; Rogozkin, V A

    2014-06-01

    Enzymes Akt, AMPK, mTOR, S6K and PGC-1a coactivator take part in skeletal muscles in the regulation of synthesis of proteins. The expression of these proteins is regulated by growth factors, hormones, nutrients, mechanical loading and leads to an increase in muscle mass and skeletal muscle hypertrophy. The review presents the results of studies published in the past four years, which expand knowledge on the effects of various factors on protein synthesis in skeletal muscle. The attention is focused on the achievements that reveal and clarify the signaling pathways involved in the regulation of protein synthesis in skeletal muscle. The central place is taken by mTOR enzyme which controls and regulates the main stages of the cascade of reactions of muscle proteins providing synthesis in the conditions of human life. coactivator PGC-1a.

  14. Effect of methylglyoxal bis(guanylhydrazone) on hepatic, heart and skeletal muscle mitochrondrial carnitine palmitoyltransferase and. beta. -oxidation of fatty acids

    Energy Technology Data Exchange (ETDEWEB)

    Brady, L.J.; Brady, P.S.; Gandour, R.D.

    1986-05-01

    Methylglyoxal bis(guanylhydrazone) (MGBG) is an antileukemic agent and polyamine analog which inhibits S-adenosyl methionine decarboxylase. However, MGBG also produces mitochondrial structural damage and inhibition of ..beta..-oxidation. The present experiments were designed to determine if MGBG acts via carnitine palmitoyltransferase-A (CPT-A) inhibition. Liver, heart and skeletal muscle mitochondria were isolated from rats following a 24 h fast. MGBG was competitive with 1-carnitine. The MGBG CPT-A Ki were (mM): liver, 5.0 +/- 0.6 (n = 15); heart, 3.2 +/- 1.2 (n = 3); skeletal muscle, 2.8 +/- 1.0 (n = 3). Lysis of hepatic mitochondria with Triton X-100 yielded a Ki of 4.0 +/- 2.0. Purified hepatic CPT was also sensitive to MGBG inhibition (Ki = 4.5 mM). Spermine and spermidine, which are structurally similar to MGBG, did not inhibit CPT or acid-soluble product formation from 1-(/sup 14/C)-palmitoyl-CoA. MGBG inhibited mitochondrial state 3 oxidation rates of palmitoyl-CoA and palmitoylcarnitine, as well as of glutamate. However, the fatty acid substrates were considerably more sensitive than glutamate to MGBG inhibition. MGBG also increased hepatic mitochondrial aggregation which was reversed by 1-carnitine. Fluorescence polarization, using diphenylhexatriene as a probe, indicated that MGBG increased membrane rigidity in a dose dependent manner. This effect was not reversed by 1-carnitine. The authors conclude that MGBG exhibits competitive competition with 1-carnitine for CPT. However, MGBG also exhibits a number of effects which may be mediated through membrane interaction and which are not necessarily reversed by carnitine.

  15. Effect of methylglyoxal bis(guanylhydrazone) on hepatic, heart and skeletal muscle mitochrondrial carnitine palmitoyltransferase and β-oxidation of fatty acids

    International Nuclear Information System (INIS)

    Brady, L.J.; Brady, P.S.; Gandour, R.D.

    1986-01-01

    Methylglyoxal bis(guanylhydrazone) (MGBG) is an antileukemic agent and polyamine analog which inhibits S-adenosyl methionine decarboxylase. However, MGBG also produces mitochondrial structural damage and inhibition of β-oxidation. The present experiments were designed to determine if MGBG acts via carnitine palmitoyltransferase-A (CPT-A) inhibition. Liver, heart and skeletal muscle mitochondria were isolated from rats following a 24 h fast. MGBG was competitive with 1-carnitine. The MGBG CPT-A Ki were (mM): liver, 5.0 +/- 0.6 (n = 15); heart, 3.2 +/- 1.2 (n = 3); skeletal muscle, 2.8 +/- 1.0 (n = 3). Lysis of hepatic mitochondria with Triton X-100 yielded a Ki of 4.0 +/- 2.0. Purified hepatic CPT was also sensitive to MGBG inhibition (Ki = 4.5 mM). Spermine and spermidine, which are structurally similar to MGBG, did not inhibit CPT or acid-soluble product formation from 1-[ 14 C]-palmitoyl-CoA. MGBG inhibited mitochondrial state 3 oxidation rates of palmitoyl-CoA and palmitoylcarnitine, as well as of glutamate. However, the fatty acid substrates were considerably more sensitive than glutamate to MGBG inhibition. MGBG also increased hepatic mitochondrial aggregation which was reversed by 1-carnitine. Fluorescence polarization, using diphenylhexatriene as a probe, indicated that MGBG increased membrane rigidity in a dose dependent manner. This effect was not reversed by 1-carnitine. The authors conclude that MGBG exhibits competitive competition with 1-carnitine for CPT. However, MGBG also exhibits a number of effects which may be mediated through membrane interaction and which are not necessarily reversed by carnitine

  16. Skeletal muscle lymphoma: observations at MR imaging

    International Nuclear Information System (INIS)

    Eustace, S.; Winalski, C.S.; McGowen, A.; Lan, H.; Dorfman, D.

    1996-01-01

    We present the MR appearances of three patients with biopsy-proven primary lymphoma of skeletal muscle. In each case lymphoma resulted in bulky expansion of the involved muscle, homogeneously isointense to skeletal muscle on T1-weighted images, homogeneously hyperintense to skeletal muscle on T2-weighted images and diffusely enhancing following intravenous administration of gadopentate dimeglumine. (orig.)

  17. Mitochondrial Alterations and Oxidative Stress in an Acute Transient Mouse Model of Muscle Degeneration

    Science.gov (United States)

    Ramadasan-Nair, Renjini; Gayathri, Narayanappa; Mishra, Sudha; Sunitha, Balaraju; Mythri, Rajeswara Babu; Nalini, Atchayaram; Subbannayya, Yashwanth; Harsha, Hindalahalli Chandregowda; Kolthur-Seetharam, Ullas; Bharath, Muchukunte Mukunda Srinivas

    2014-01-01

    Muscular dystrophies (MDs) and inflammatory myopathies (IMs) are debilitating skeletal muscle disorders characterized by common pathological events including myodegeneration and inflammation. However, an experimental model representing both muscle pathologies and displaying most of the distinctive markers has not been characterized. We investigated the cardiotoxin (CTX)-mediated transient acute mouse model of muscle degeneration and compared the cardinal features with human MDs and IMs. The CTX model displayed degeneration, apoptosis, inflammation, loss of sarcolemmal complexes, sarcolemmal disruption, and ultrastructural changes characteristic of human MDs and IMs. Cell death caused by CTX involved calcium influx and mitochondrial damage both in murine C2C12 muscle cells and in mice. Mitochondrial proteomic analysis at the initial phase of degeneration in the model detected lowered expression of 80 mitochondrial proteins including subunits of respiratory complexes, ATP machinery, fatty acid metabolism, and Krebs cycle, which further decreased in expression during the peak degenerative phase. The mass spectrometry (MS) data were supported by enzyme assays, Western blot, and histochemistry. The CTX model also displayed markers of oxidative stress and a lowered glutathione reduced/oxidized ratio (GSH/GSSG) similar to MDs, human myopathies, and neurogenic atrophies. MS analysis identified 6 unique oxidized proteins from Duchenne muscular dystrophy samples (n = 6) (versus controls; n = 6), including two mitochondrial proteins. Interestingly, these mitochondrial proteins were down-regulated in the CTX model thereby linking oxidative stress and mitochondrial dysfunction. We conclude that mitochondrial alterations and oxidative damage significantly contribute to CTX-mediated muscle pathology with implications for human muscle diseases. PMID:24220031

  18. Thyroid hormones regulate skeletal muscle regeneration after acute injury.

    Science.gov (United States)

    Leal, Anna Lúcia R C; Albuquerque, João Paulo C; Matos, Marina S; Fortunato, Rodrigo S; Carvalho, Denise P; Rosenthal, Doris; da Costa, Vânia Maria Corrêa

    2015-02-01

    We evaluated the effects of hypo- and hyperthyroid statuses during the initial phase of skeletal muscle regeneration in rats. To induce hypo- or hyperthyroidism, adult male Wistar rats were treated with methimazole (0.03%) or T4 (10 μg/100 g), respectively, for 10 days. Three days before sacrifice, a crush injury was produced in the solear muscles of one half of the animals, while the other half remained intact. T3, T4, TSH, and leptin serum levels were not affected by the injury. Serum T3 and T4 levels were significantly increased in hyperthyroid and hyper-injury animals. Hypothyroidism was confirmed by the significant increase in serum TSH levels in hypothyroid and hypo-injury animals. Injury increased cell infiltration and macrophage accumulation especially in hyperthyroid animals. Both type 2 and type 3 deiodinases were induced by lesion, and the opposite occurred with the type 1 isoform, at least in the control and hyperthyroid groups. Injury increased both MyoD and myogenin expression in all the studied groups, but only MyoD expression was increased by thyroidal status only at the protein level. We conclude that thyroid hormones modulate skeletal muscle regeneration possibly by regulating the inflammatory process, as well as MyoD and myogenin expression in the injured tissue.

  19. Adaptation of motor unit contractile properties in rat medial gastrocnemius to treadmill endurance training: Relationship to muscle mitochondrial biogenesis.

    Science.gov (United States)

    Kryściak, Katarzyna; Majerczak, Joanna; Kryściak, Jakub; Łochyński, Dawid; Kaczmarek, Dominik; Drzymała-Celichowska, Hanna; Krutki, Piotr; Gawedzka, Anna; Guzik, Magdalena; Korostynski, Michał; Szkutnik, Zbigniew; Pyza, Elżbieta; Jarmuszkiewicz, Wiesława; Zoladz, Jerzy A; Celichowski, Jan

    2018-01-01

    This study aimed at investigating the effects of 2, 4 and 8 weeks of endurance training on the contractile properties of slow (S), fast fatigue resistant (FR) and fast fatigable (FF) motor units (MUs) in rat medial gastrocnemius (MG) in relation to the changes in muscle mitochondrial biogenesis. The properties of functionally isolated MUs were examined in vivo. Mitochondrial biogenesis was judged based on the changes in mitochondrial DNA copy number (mtDNA), the content of the electron transport chain (ETC) proteins and PGC-1α in the MG. Moreover, the markers of mitochondria remodeling mitofusins (Mfn1, Mfn2) and dynamin-like protein (Opa1) were studied using qPCR. A proportion of FR MUs increased from 37.9% to 50.8% and a proportion of FF units decreased from 44.7% to 26.6% after 8 weeks of training. The increased fatigue resistance, shortened twitch duration, and increased ability to potentiate force were found as early as after 2 weeks of endurance training, predominantly in FR MUs. Moreover, just after 2 weeks of the training an enhancement of the mitochondrial network remodeling was present as judged by an increase in expression of Mfn1, Opa1 and an increase in PGC-1α in the slow part of MG. Interestingly, no signs of intensification of mitochondrial biogenesis assessed by ETC proteins content and mtDNA in slow and fast parts of gastrocnemius were found at this stage of the training. Nevertheless, after 8 weeks of training an increase in the ETC protein content was observed, but mainly in the slow part of gastrocnemius. Concluding, the functional changes in MUs' contractile properties leading to the enhancement of muscle performance accompanied by an activation of signalling that controls the muscle mitochondrial network reorganisation and mitochondrial biogenesis belong to an early muscle adaptive responses that precede an increase in mitochondrial ETC protein content.

  20. Basal and insulin-stimulated skeletal muscle sugar transport in endotoxic and bacteremic rats

    International Nuclear Information System (INIS)

    Westfall, M.V.; Sayeed, M.M.

    1988-01-01

    Membrane glucose transport with and without insulin was studied in soleus muscle from 5-h endotoxic rats (40 mg/kg Salmonella enteritidis lipopolysaccharide), and in soleus and epitrochlearis muscles from 12-h bacteremic (Escherichia coli, 4 X 10(10) CFU/kg) rats. Glucose transport was measured in muscles by evaluating the fractional efflux of 14 C-labeled 3-O-methylglucose ( 14 C-3-MG) after loading muscles with 14 C-3-MG. Basal 3-MG transport was elevated in soleus muscles from endotoxic as well as in soleus and epitrochlearis muscles from bacteremic rats compared with time-matched controls. Low insulin concentrations stimulated 14 C-3-MG transport more in bacteremic and endotoxic rat muscles than in controls. However, sugar transport in the presence of high insulin dose was attenuated in soleus and epitrochlearis muscles from bacteremic rats and soleus muscles from endotoxic rats compared with controls. Analysis of the dose-response relationship with ALLFIT revealed that the maximal transport response to insulin was significantly decreased in both models of septic shock. Sensitivity to insulin (EC50) was increased in endotoxic rat muscles, and a somewhat similar tendency was observed in bacteremic rat soleus muscles. Neural and humoral influences and/or changes in cellular metabolic energy may contribute to the increase in basal transport. Shifts in insulin-mediated transport may be due to alterations in insulin-receptor-effector coupling and/or the number of available glucose transporters

  1. Effect of regional muscle location but not adiposity on mitochondrial biogenesis-regulating proteins

    DEFF Research Database (Denmark)

    Ponce-González, Jesús Gustavo; Ara, Ignacio; Larsen, Steen

    2016-01-01

    PURPOSE: The aim of this study was to determine if the expression of the mitochondrial biogenesis-regulating proteins SIRT1, SIRT3 and PGC-1alpha in human skeletal muscle is influenced by adiposity. METHOD: Twenty-nine male subjects were recruited into three groups: control (n = 10), obese (n = 10...

  2. Defective mitochondrial function in vivo in skeletal muscle in adults with Down's syndrome: a 31P-MRS study.

    Directory of Open Access Journals (Sweden)

    Alexander C Phillips

    Full Text Available Down's syndrome (DS is a developmental disorder associated with intellectual disability (ID. We have previously shown that people with DS engage in very low levels of exercise compared to people with ID not due to DS. Many aspects of the DS phenotype, such as dementia, low activity levels and poor muscle tone, are shared with disorders of mitochondrial origin, and mitochondrial dysfunction has been demonstrated in cultured DS tissue. We undertook a phosphorus magnetic resonance spectroscopy ((31P-MRS study in the quadriceps muscle of 14 people with DS and 11 non-DS ID controls to investigate the post-exercise resynthesis kinetics of phosphocreatine (PCr, which relies on mitochondrial respiratory function and yields a measure of muscle mitochondrial function in vivo. We found that the PCr recovery rate constant was significantly decreased in adults with DS compared to non-DS ID controls (1.7 ± 0.1 min(-1 vs 2.1 ± 0.1 min(-1 respectively who were matched for physical activity levels, indicating that muscle mitochondrial function in vivo is impaired in DS. This is the first study to investigate mitochondrial function in vivo in DS using (31P-MRS. Our study is consistent with previous in vitro studies, supporting a theory of a global mitochondrial defect in DS.

  3. The effect of diuretics and lithium on 3H-ouabain binding site concentration and Na,K-content in rat skeletal muscle

    International Nuclear Information System (INIS)

    Noergaard, Aa.; Kjeldsen, K.

    1986-01-01

    Previous studies have shown an increase in 3 H-ouabain binding sites or Na,K-pumps in vitro in cultured cells in response to incubation in low K, diuretics or lithium. However, in the present study the administration in vivo of various diuretics or lithium combined with supplementary K was not associated with any significant changes in Na,K-content or 3 H-ouabain binding site concentration in rat skeletal muscle. When the diuretics were administered in combination with only the basal K requirement a decrease in both K-content and 3 H-ouabain binding site concentration was seen. This indicates that the decrease in 3 H-ouabain binding site concentration is not caused by these drugs per se but is secondary to the associated K-depletion. The discrepancy between the results obtained using isolated cells and rat skeletal muscles could be related to the fact that cultured cells are not subjected to the normal growth control of the intact organism. It should be emphasized that results obtained using cultured cells do not necessarily reflect processes taking place in the intact organism. (author)

  4. PEDF-derived peptide promotes skeletal muscle regeneration through its mitogenic effect on muscle progenitor cells.

    Science.gov (United States)

    Ho, Tsung-Chuan; Chiang, Yi-Pin; Chuang, Chih-Kuang; Chen, Show-Li; Hsieh, Jui-Wen; Lan, Yu-Wen; Tsao, Yeou-Ping

    2015-08-01

    In response injury, intrinsic repair mechanisms are activated in skeletal muscle to replace the damaged muscle fibers with new muscle fibers. The regeneration process starts with the proliferation of satellite cells to give rise to myoblasts, which subsequently differentiate terminally into myofibers. Here, we investigated the promotion effect of pigment epithelial-derived factor (PEDF) on muscle regeneration. We report that PEDF and a synthetic PEDF-derived short peptide (PSP; residues Ser(93)-Leu(112)) induce satellite cell proliferation in vitro and promote muscle regeneration in vivo. Extensively, soleus muscle necrosis was induced in rats by bupivacaine, and an injectable alginate gel was used to release the PSP in the injured muscle. PSP delivery was found to stimulate satellite cell proliferation in damaged muscle and enhance the growth of regenerating myofibers, with complete regeneration of normal muscle mass by 2 wk. In cell culture, PEDF/PSP stimulated C2C12 myoblast proliferation, together with a rise in cyclin D1 expression. PEDF induced the phosphorylation of ERK1/2, Akt, and STAT3 in C2C12 myoblasts. Blocking the activity of ERK, Akt, or STAT3 with pharmacological inhibitors attenuated the effects of PEDF/PSP on the induction of C2C12 cell proliferation and cyclin D1 expression. Moreover, 5-bromo-2'-deoxyuridine pulse-labeling demonstrated that PEDF/PSP stimulated primary rat satellite cell proliferation in myofibers in vitro. In summary, we report for the first time that PSP is capable of promoting the regeneration of skeletal muscle. The signaling mechanism involves the ERK, AKT, and STAT3 pathways. These results show the potential utility of this PEDF peptide for muscle regeneration. Copyright © 2015 the American Physiological Society.

  5. Diaphragmatic lymphatic vessel behavior during local skeletal muscle contraction.

    Science.gov (United States)

    Moriondo, Andrea; Solari, Eleonora; Marcozzi, Cristiana; Negrini, Daniela

    2015-02-01

    The mechanism through which the stresses developed in the diaphragmatic tissue during skeletal muscle contraction sustain local lymphatic function was studied in 10 deeply anesthetized, tracheotomized adult Wistar rats whose diaphragm was exposed after thoracotomy. To evaluate the direct effect of skeletal muscle contraction on the hydraulic intraluminal lymphatic pressures (Plymph) and lymphatic vessel geometry, the maximal contraction of diaphragmatic fibers adjacent to a lymphatic vessel was elicited by injection of 9.2 nl of 1 M KCl solution among diaphragmatic fibers while Plymph was recorded through micropuncture and vessel geometry via stereomicroscopy video recording. In lymphatics oriented perpendicularly to the longitudinal axis of muscle fibers and located at skeletal muscle contraction (Dmc) decreased to 61.3 ± 1.4% of the precontraction value [resting diameter (Drest)]; however, if injection was at >900 μm from the vessel, Dmc enlarged to 131.1 ± 2.3% of Drest. In vessels parallel to muscle fibers, Dmc increased to 122.8 ± 2.9% of Drest. During contraction, Plymph decreased as much as 22.5 ± 2.6 cmH2O in all submesothelial superficial vessels, whereas it increased by 10.7 ± 5.1 cmH2O in deeper vessels running perpendicular to contracting muscle fibers. Hence, the three-dimensional arrangement of the diaphragmatic lymphatic network seems to be finalized to efficiently exploit the stresses exerted by muscle fibers during the contracting inspiratory phase to promote lymph formation in superficial submesothelial lymphatics and its further propulsion in deeper intramuscular vessels. Copyright © 2015 the American Physiological Society.

  6. Raman spectroscopic study of acute oxidative stress induced changes in mice skeletal muscles

    Science.gov (United States)

    Sriramoju, Vidyasagar; Alimova, Alexandra; Chakraverty, Rahul; Katz, A.; Gayen, S. K.; Larsson, L.; Savage, H. E.; Alfano, R. R.

    2008-02-01

    The oxidative stress due to free radicals is implicated in the pathogenesis of tissue damage in diseases such as muscular dystrophy, Alzheimer dementia, diabetes mellitus, and mitochrondrial myopathies. In this study, the acute oxidative stress induced changes in nicotinamide adenine dinucleotides in mouse skeletal muscles are studied in vitro using Raman spectroscopy. Mammalian skeletal muscles are rich in nicotinamide adenine dinucleotides in both reduced (NADH) and oxidized (NAD) states, as they are sites of aerobic and anaerobic respiration. The relative levels of NAD and NADH are altered in certain physiological and pathological conditions of skeletal muscles. In this study, near infrared Raman spectroscopy is used to identify the molecular fingerprints of NAD and NADH in five-week-old mice biceps femoris muscles. A Raman vibrational mode of NADH is identified in fresh skeletal muscle samples suspended in buffered normal saline. In the same samples, when treated with 1% H IIO II for 5 minutes and 15 minutes, the Raman spectrum shows molecular fingerprints specific to NAD and the disappearance of NADH vibrational bands. The NAD bands after 15 minutes were more intense than after 5 minutes. Since NADH fluoresces and NAD does not, fluorescence spectroscopy is used to confirm the results of the Raman measurements. Fluorescence spectra exhibit an emission peak at 460 nm, corresponding to NADH emission wavelength in fresh muscle samples; while the H IIO II treated muscle samples do not exhibit NADH fluorescence. Raman spectroscopy may be used to develop a minimally invasive, in vivo optical biopsy method to measure the relative NAD and NADH levels in muscle tissues. This may help to detect diseases of muscle, including mitochondrial myopathies and muscular dystrophies.

  7. Fasting- and Exercise-Induced PDH Regulation in Skeletal Muscle

    DEFF Research Database (Denmark)

    Gudiksen, Anders

    in selected mitochondrial proteins. Lastly, increased oxidative capacity leads to exercise-induced skeletal muscle PDH activation that is closely matched to the relative exercise intensity at submaximal exercise, while reaching a higher level at maximal exercise in trained individuals. These responses......Pyruvate dehydrogenase PDH constitutes the only mammalian pathway for irreversible conversion of pyruvate to acetyl-CoA thus providing the vital link between glycolytic energy production, the TCA cycle, and oxidative phosphorylation. Because the PDC controls the conversion of pyruvate it occupies...... a central position in relation to the control of mitochondrial energy production and cellular substrate metabolism. Suppression and activation of PDH becomes essential in situations where glucose availability and/or use changes with swift and appropriate regulation of the complex to maintain energy...

  8. Mitochondria mediate tumor necrosis factor-alpha/NF-kappaB signaling in skeletal muscle myotubes

    Science.gov (United States)

    Li, Y. P.; Atkins, C. M.; Sweatt, J. D.; Reid, M. B.; Hamilton, S. L. (Principal Investigator)

    1999-01-01

    Tumor necrosis factor-alpha (TNF-alpha) is implicated in muscle atrophy and weakness associated with a variety of chronic diseases. Recently, we reported that TNF-alpha directly induces muscle protein degradation in differentiated skeletal muscle myotubes, where it rapidly activates nuclear factor kappaB (NF-kappaB). We also have found that protein loss induced by TNF-alpha is NF-kappaB dependent. In the present study, we analyzed the signaling pathway by which TNF-alpha activates NF-kappaB in myotubes differentiated from C2C12 and rat primary myoblasts. We found that activation of NF-kappaB by TNF-alpha was blocked by rotenone or amytal, inhibitors of complex I of the mitochondrial respiratory chain. On the other hand, antimycin A, an inhibitor of complex III, enhanced TNF-alpha activation of NK-kappaB. These results suggest a key role of mitochondria-derived reactive oxygen species (ROS) in mediating NF-kappaB activation in muscle. In addition, we found that TNF-alpha stimulated protein kinase C (PKC) activity. However, other signal transduction mediators including ceramide, Ca2+, phospholipase A2 (PLA2), and nitric oxide (NO) do not appear to be involved in the activation of NF-kappaB.

  9. Both short intense and prolonged moderate in vitro stimulation reduce the mRNA expression of calcium-regulatory proteins in rat skeletal muscle

    DEFF Research Database (Denmark)

    Mänttäri, Satu; Ørtenblad, N; Madsen, Klavs

    2013-01-01

    RNA expression of components involved in Ca(2+) regulation in oxidative and glycolytic skeletal muscle. The mRNA level of Ca(2+)-ATPase (SERCA1, 2), calsequestrin (CASQ1, 2), ryanodine receptor (RyR1), and dihydropyridine receptor (Cacna1) was assessed in rat extensor digitorum longus (EDL) and soleus (SOL...

  10. Expression of developmental myosin and morphological characteristics in adult rat skeletal muscle following exercise-induced injury.

    Science.gov (United States)

    Smith, H K; Plyley, M J; Rodgers, C D; McKee, N H

    1999-07-01

    The extent and stability of the expression of developmental isoforms of myosin heavy chain (MHCd), and their association with cellular morphology, were determined in adult rat skeletal muscle fibres following injury induced by eccentrically-biased exercise. Adult female Wistar rats [274 (10) g] were either assigned as non-exercised controls or subjected to 30 min of treadmill exercise (grade, -16 degrees; speed, 15 m x min(-1)), and then sacrificed following 1, 2, 4, 7, or 12 days of recovery (n = 5-6 per group). Histologically and immunohistologically stained serial, transverse cryosections of the soleus (S), vastus intermedius (VI), and tibialis anterior (TA) muscles were examined using light microscopy and digital imaging. Fibres staining positively for MHCd (MHCd+) were seldom detected in the TA. In the VI and S, higher proportions of MHCd+ fibres (0.8% and 2.5%, respectively) were observed in rats at 4 and 7 days post-exercise, in comparison to all other groups combined (0.2%, 1.2%; P < or = 0.01). In S, MHCd+ fibres were observed less frequently by 12 days (0.7%) than at 7 days (2.6%) following exercise. The majority (85.1%) of the MHCd+ fibres had morphological characteristics indicative of either damage, degeneration, repair or regeneration. Most of the MHCd+ fibres also expressed adult slow, and/or fast myosin heavy chain. Quantitatively, the MHCd+ fibres were smaller (< 2500 microm2) and more angular than fibres not expressing MHCd. Thus, there was a transient increase in a small, but distinct population of MHCd+ fibres following unaccustomed, functional exercise in adult rat S and VI muscles. The observed close coupling of MHCd expression with morphological changes within muscle fibres suggests that these characteristics have a common, initial exercise-induced injury-related stimulus.

  11. Skeletal muscle contraction-induced vasodilation in the microcirculation.

    Science.gov (United States)

    Hong, Kwang-Seok; Kim, Kijeong

    2017-10-01

    Maximal whole body exercise leads skeletal muscle blood flow to markedly increase to match metabolic demands, a phenomenon termed exercise hyperaemia that is accomplished by increasing vasodilation. However, local vasodilatory mechanisms in response to skeletal muscle contraction remain uncertain. This review highlights metabolic vasodilators released from contracting skeletal muscle, endothelium, or blood cells. As a considerable skeletal muscle vasodilation potentially results in hypotension, sympathetic nerve activity needs to be augmented to elevate cardiac output and blood pressure during dynamic exercise. However, since the enhanced sympathetic vasoconstriction restrains skeletal muscle blood flow, intramuscular arteries have an indispensable ability to blunt sympathetic activity for exercise hyperaemia. In addition, we discuss that mechanical compression of the intramuscular vasculature contributes to causing the initial phase of increasing vasodilation following a single muscle contraction. We have also chosen to focus on conducted (or ascending) electrical signals that evoke vasodilation of proximal feed arteries to elevate blood flow in the microcirculation of skeletal muscle. Endothelial hyperpolarization originating within distal arterioles ascends into the proximal feed arteries, thereby increasing total blood flow in contracting skeletal muscle. This brief review summarizes molecular mechanisms underlying the regulation of skeletal muscle blood flow to a single or sustained muscle contraction.

  12. Exercise Training-Induced Adaptations Associated with Increases in Skeletal Muscle Glycogen Content

    Science.gov (United States)

    Manabe, Yasuko; Gollisch, Katja S.C.; Holton, Laura; Kim, Young–Bum; Brandauer, Josef; Fujii, Nobuharu L.; Hirshman, Michael F.; Goodyear, Laurie J.

    2012-01-01

    Chronic exercise training results in numerous skeletal muscle adaptations, including increases in insulin sensitivity and glycogen content. To understand the mechanism for increased muscle glycogen, we studied the effects of exercise training on glycogen regulatory proteins in rat skeletal muscle. Female Sprague Dawley rats performed voluntary wheel running for 1, 4, or 7 weeks. After 7 weeks of training, insulin-stimulated glucose uptake was increased in epitrochlearis muscle. Compared to sedentary control rats, muscle glycogen did not change after 1 week of training, but increased significantly after 4 and 7 weeks. The increases in muscle glycogen were accompanied by elevated glycogen synthase activity and protein expression. To assess the regulation of glycogen synthase, we examined its major activator, protein phosphatase 1 (PP1), and its major deactivator, glycogen synthase kinase 3 (GSK3). Consistent with glycogen synthase activity, PP1 activity was unchanged after 1 week of training but significantly increased after 4 and 7 weeks of training. Protein expression of RGL(GM), another regulatory PP1 subunit, significantly decreased after 4 and 7 weeks of training. Unlike PP1, GSK3 phosphorylation did not follow the pattern of glycogen synthase activity. The ~40% decrease in GSK-3α phosphorylation after 1 week of exercise training persisted until 7 weeks and may function as a negative feedback to elevated glycogen. Our findings suggest that exercise training-induced increases in muscle glycogen content could be regulated by multiple mechanisms including enhanced insulin sensitivity, glycogen synthase expression, allosteric activation of glycogen synthase and PP1activity. PMID:23206309

  13. Mitochondrial alterations and oxidative stress in an acute transient mouse model of muscle degeneration: implications for muscular dystrophy and related muscle pathologies.

    Science.gov (United States)

    Ramadasan-Nair, Renjini; Gayathri, Narayanappa; Mishra, Sudha; Sunitha, Balaraju; Mythri, Rajeswara Babu; Nalini, Atchayaram; Subbannayya, Yashwanth; Harsha, Hindalahalli Chandregowda; Kolthur-Seetharam, Ullas; Srinivas Bharath, Muchukunte Mukunda

    2014-01-03

    Muscular dystrophies (MDs) and inflammatory myopathies (IMs) are debilitating skeletal muscle disorders characterized by common pathological events including myodegeneration and inflammation. However, an experimental model representing both muscle pathologies and displaying most of the distinctive markers has not been characterized. We investigated the cardiotoxin (CTX)-mediated transient acute mouse model of muscle degeneration and compared the cardinal features with human MDs and IMs. The CTX model displayed degeneration, apoptosis, inflammation, loss of sarcolemmal complexes, sarcolemmal disruption, and ultrastructural changes characteristic of human MDs and IMs. Cell death caused by CTX involved calcium influx and mitochondrial damage both in murine C2C12 muscle cells and in mice. Mitochondrial proteomic analysis at the initial phase of degeneration in the model detected lowered expression of 80 mitochondrial proteins including subunits of respiratory complexes, ATP machinery, fatty acid metabolism, and Krebs cycle, which further decreased in expression during the peak degenerative phase. The mass spectrometry (MS) data were supported by enzyme assays, Western blot, and histochemistry. The CTX model also displayed markers of oxidative stress and a lowered glutathione reduced/oxidized ratio (GSH/GSSG) similar to MDs, human myopathies, and neurogenic atrophies. MS analysis identified 6 unique oxidized proteins from Duchenne muscular dystrophy samples (n = 6) (versus controls; n = 6), including two mitochondrial proteins. Interestingly, these mitochondrial proteins were down-regulated in the CTX model thereby linking oxidative stress and mitochondrial dysfunction. We conclude that mitochondrial alterations and oxidative damage significantly contribute to CTX-mediated muscle pathology with implications for human muscle diseases.

  14. Accurate measurement of mitochondrial DNA deletion level and copy number differences in human skeletal muscle.

    Directory of Open Access Journals (Sweden)

    John P Grady

    Full Text Available Accurate and reliable quantification of the abundance of mitochondrial DNA (mtDNA molecules, both wild-type and those harbouring pathogenic mutations, is important not only for understanding the progression of mtDNA disease but also for evaluating novel therapeutic approaches. A clear understanding of the sensitivity of mtDNA measurement assays under different experimental conditions is therefore critical, however it is routinely lacking for most published mtDNA quantification assays. Here, we comprehensively assess the variability of two quantitative Taqman real-time PCR assays, a widely-applied MT-ND1/MT-ND4 multiplex mtDNA deletion assay and a recently developed MT-ND1/B2M singleplex mtDNA copy number assay, across a range of DNA concentrations and mtDNA deletion/copy number levels. Uniquely, we provide a specific guide detailing necessary numbers of sample and real-time PCR plate replicates for accurately and consistently determining a given difference in mtDNA deletion levels and copy number in homogenate skeletal muscle DNA.

  15. Overexpression of PGC-1α Increases Fatty Acid Oxidative Capacity of Human Skeletal Muscle Cells

    Directory of Open Access Journals (Sweden)

    Nataša Nikolić

    2012-01-01

    Full Text Available We investigated the effects of PGC-1α (peroxisome proliferator-activated receptor γ coactivator-1α overexpression on the oxidative capacity of human skeletal muscle cells ex vivo. PGC-1α overexpression increased the oxidation rate of palmitic acid and mRNA expression of genes regulating lipid metabolism, mitochondrial biogenesis, and function in human myotubes. Basal and insulin-stimulated deoxyglucose uptake were decreased, possibly due to upregulation of PDK4 mRNA. Expression of fast fiber-type gene marker (MHCIIa was decreased. Compared to skeletal muscle in vivo, PGC-1α overexpression increased expression of several genes, which were downregulated during the process of cell isolation and culturing. In conclusion, PGC-1α overexpression increased oxidative capacity of cultured myotubes by improving lipid metabolism, increasing expression of genes involved in regulation of mitochondrial function and biogenesis, and decreasing expression of MHCIIa. These results suggest that therapies aimed at increasing PGC-1α expression may have utility in treatment of obesity and obesity-related diseases.

  16. Rat whisker movement after facial nerve lesion: evidence for autonomic contraction of skeletal muscle.

    Science.gov (United States)

    Heaton, James T; Sheu, Shu Hsien; Hohman, Marc H; Knox, Christopher J; Weinberg, Julie S; Kleiss, Ingrid J; Hadlock, Tessa A

    2014-04-18

    Vibrissal whisking is often employed to track facial nerve regeneration in rats; however, we have observed similar degrees of whisking recovery after facial nerve transection with or without repair. We hypothesized that the source of non-facial nerve-mediated whisker movement after chronic denervation was from autonomic, cholinergic axons traveling within the infraorbital branch of the trigeminal nerve (ION). Rats underwent unilateral facial nerve transection with repair (N=7) or resection without repair (N=11). Post-operative whisking amplitude was measured weekly across 10weeks, and during intraoperative stimulation of the ION and facial nerves at ⩾18weeks. Whisking was also measured after subsequent ION transection (N=6) or pharmacologic blocking of the autonomic ganglia using hexamethonium (N=3), and after snout cooling intended to elicit a vasodilation reflex (N=3). Whisking recovered more quickly and with greater amplitude in rats that underwent facial nerve repair compared to resection (Pfacial-nerve-mediated whisking was elicited by electrical stimulation of the ION, temporarily diminished following hexamethonium injection, abolished by transection of the ION, and rapidly and significantly (Pfacial nerve resection. This study provides the first behavioral and anatomical evidence of spontaneous autonomic innervation of skeletal muscle after motor nerve lesion, which not only has implications for interpreting facial nerve reinnervation results, but also calls into question whether autonomic-mediated innervation of striated muscle occurs naturally in other forms of neuropathy. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

  17. Peripheral nerve injury causes transient expression of MHC class I antigens in rat motor neurons and skeletal muscles

    DEFF Research Database (Denmark)

    Maehlen, J; Nennesmo, I; Olsson, A B

    1989-01-01

    After a peripheral nerve lesion (rat facial and sciatic) an induction of major histocompatibility complex (MHC) antigens class I was detected immunohistochemically in skeletal muscle fibers and motor neurons. This MHC expression was transient after a nerve crush, when regeneration occurred......, but persisted after a nerve cut, when regeneration was prevented. Since the time course of MHC class I expression correlates to that of regeneration a role for this cell surface molecule in regeneration may be considered....

  18. Mechanical modeling of skeletal muscle functioning

    NARCIS (Netherlands)

    van der Linden, B.J.J.J.

    1998-01-01

    For movement of body or body segments is combined effort needed of the central nervous system and the muscular-skeletal system. This thesis deals with the mechanical functioning of skeletal muscle. That muscles come in a large variety of geometries, suggest the existence of a relation between muscle

  19. Skeletal muscle expression of p43, a truncated thyroid hormone receptor α, affects lipid composition and metabolism.

    Science.gov (United States)

    Casas, François; Fouret, Gilles; Lecomte, Jérome; Cortade, Fabienne; Pessemesse, Laurence; Blanchet, Emilie; Wrutniak-Cabello, Chantal; Coudray, Charles; Feillet-Coudray, Christine

    2018-02-01

    Thyroid hormone is a major regulator of metabolism and mitochondrial function. Thyroid hormone also affects reactions in almost all pathways of lipids metabolism and as such is considered as the main hormonal regulator of lipid biogenesis. The aim of this study was to explore the possible involvement of p43, a 43 Kda truncated form of the nuclear thyroid hormone receptor TRα1 which stimulates mitochondrial activity. Therefore, using mouse models overexpressing p43 in skeletal muscle (p43-Tg) or lacking p43 (p43-/-), we have investigated the lipid composition in quadriceps muscle and in mitochondria. Here, we reported in the quadriceps muscle of p43-/- mice, a fall in triglycerides, an inhibition of monounsaturated fatty acids (MUFA) synthesis, an increase in elongase index and an decrease in desaturase index. However, in mitochondria from p43-/- mice, fatty acid profile was barely modified. In the quadriceps muscle of p43-Tg mice, MUFA content was decreased whereas the unsaturation index was increased. In addition, in quadriceps mitochondria of p43-Tg mice, we found an increase of linoleic acid level and unsaturation index. Last, we showed that cardiolipin content, a key phospholipid for mitochondrial function, remained unchanged both in quadriceps muscle and in its mitochondria whatever the mice genotype. In conclusion, this study shows that muscle lipid content and fatty acid profile are strongly affected in skeletal muscle by p43 levels. We also demonstrate that regulation of cardiolipin biosynthesis by the thyroid hormone does not imply p43.

  20. Do antioxidant supplements interfere with skeletal muscle adaptation to exercise training?

    Science.gov (United States)

    Ristow, Michael

    2016-01-01

    Abstract A popular belief is that reactive oxygen species (ROS) and reactive nitrogen species (RNS) produced during exercise by the mitochondria and other subcellular compartments ubiquitously cause skeletal muscle damage, fatigue and impair recovery. However, the importance of ROS and RNS as signals in the cellular adaptation process to stress is now evident. In an effort to combat the perceived deleterious effects of ROS and RNS it has become common practice for active individuals to ingest supplements with antioxidant properties, but interfering with ROS/RNS signalling in skeletal muscle during acute exercise may blunt favourable adaptation. There is building evidence that antioxidant supplementation can attenuate endurance training‐induced and ROS/RNS‐mediated enhancements in antioxidant capacity, mitochondrial biogenesis, cellular defence mechanisms and insulin sensitivity. However, this is not a universal finding, potentially indicating that there is redundancy in the mechanisms controlling skeletal muscle adaptation to exercise, meaning that in some circumstances the negative impact of antioxidants on acute exercise response can be overcome by training. Antioxidant supplementation has been more consistently reported to have deleterious effects on the response to overload stress and high‐intensity training, suggesting that remodelling of skeletal muscle following resistance and high‐intensity exercise is more dependent on ROS/RNS signalling. Importantly there is no convincing evidence to suggest that antioxidant supplementation enhances exercise‐training adaptions. Overall, ROS/RNS are likely to exhibit a non‐linear (hormetic) pattern on exercise adaptations, where physiological doses are beneficial and high exposure (which would seldom be achieved during normal exercise training) may be detrimental. PMID:26638792

  1. Low intensity exercise training improves skeletal muscle regeneration potential

    Directory of Open Access Journals (Sweden)

    Tiziana ePietrangelo

    2015-12-01

    Full Text Available Purpose: The aim of this study was to determine whether 12 days of low-to-moderate exercise training at low altitude (598 m a.s.l. improves skeletal muscle regeneration in sedentary adult women.Methods: Satellite cells were obtained from the vastus lateralis skeletal muscle of seven women before and after this exercise training at low altitude. They were investigated for differentiation aspects, superoxide anion production, antioxidant enzymes, mitochondrial potential variation after a depolarizing insult, intracellular Ca2+ concentrations, and micro (miRNA expression (miR-1, miR-133, miR-206.Results: In these myogenic populations of adult stem cells, those obtained after exercise training, showed increased Fusion Index and intracellular Ca2+ concentrations. This exercise training also generally reduced superoxide anion production in cells (by 12% to 67%, although not in two women, where there was an increase of ~15% along with a reduced superoxide dismutase activity. miRNA expression showed an exercise-induced epigenetic transcription profile that was specific according to the reduced or increased superoxide anion production of the cells. Conclusions: The present study shows that low-to-moderate exercise training at low altitude improves the regenerative capacity of skeletal muscle in adult women. The differentiation of cells was favored by increased intracellular calcium concentration and increased the fusion index. This low-to-moderate training at low altitude also depicted the epigenetic signature of cells.

  2. Attenuated fatigue in slow twitch skeletal muscle during isotonic exercise in rats with chronic heart failure.

    Directory of Open Access Journals (Sweden)

    Morten Munkvik

    Full Text Available During isometric contractions, slow twitch soleus muscles (SOL from rats with chronic heart failure (chf are more fatigable than those of sham animals. However, a muscle normally shortens during activity and fatigue development is highly task dependent. Therefore, we examined the development of skeletal muscle fatigue during shortening (isotonic contractions in chf and sham-operated rats. Six weeks following coronary artery ligation, infarcted animals were classified as failing (chf if left ventricle end diastolic pressure was >15 mmHg. During isoflurane anaesthesia, SOL with intact blood supply was stimulated (1s on 1s off at 30 Hz for 15 min and allowed to shorten isotonically against a constant afterload. Muscle temperature was maintained at 37°C. In resting muscle, maximum isometric force (F(max and the concentrations of ATP and CrP were not different in the two groups. During stimulation, F(max and the concentrations declined in parallel sham and chf. Fatigue, which was evident as reduced shortening during stimulation, was also not different in the two groups. The isometric force decline was fitted to a bi-exponential decay equation. Both time constants increased transiently and returned to initial values after approximately 200 s of the fatigue protocol. This resulted in a transient rise in baseline tension between stimulations, although this effect which was less prominent in chf than sham. Myosin light chain 2s phosphorylation declined in both groups after 100 s of isotonic contractions, and remained at this level throughout 15 min of stimulation. In spite of higher energy demand during isotonic than isometric contractions, both shortening capacity and rate of isometric force decline were as well or better preserved in fatigued SOL from chf rats than in sham. This observation is in striking contrast to previous reports which have employed isometric contractions to induce fatigue.

  3. Lactate dehydrogenase is not a mitochondrial enzyme in human and mouse vastus lateralis muscle

    DEFF Research Database (Denmark)

    Rasmussen, Hans N; van Hall, Gerrit; Rasmussen, Ulla F

    2002-01-01

    The presence of lactate dehydrogenase in skeletal muscle mitochondria was investigated to clarify whether lactate is a possible substrate for mitochondrial respiration. Mitochondria were prepared from 100 mg samples of human and mouse vastus lateralis muscle. All fractions from the preparation...... procedure were assayed for marker enzymes and lactate dehydrogenase (LDH). The mitochondrial fraction contained no LDH activity (detection limit approximately 0.05 % of the tissue activity) and the distribution of LDH activity among the fractions paralleled that of pyruvate kinase, i.e. LDH was fractionated...... as a cytoplasmic enzyme. Respiratory experiments with the mitochondrial fraction also indicated the absence of LDH. Lactate did not cause respiration, nor did it affect the respiration of pyruvate + malate. The major part of the native cytochrome c was retained in the isolated mitochondria, which, furthermore...

  4. Reduced skeletal muscle mitochondrial respiration and improved glucose metabolism in nondiabetic obese women during a very low calorie dietary intervention leading to rapid weight loss

    DEFF Research Database (Denmark)

    Rabøl, Rasmus; Svendsen, Pernille F; Skovbro, Mette

    2009-01-01

    Reduced oxidative capacity of skeletal muscle has been proposed to lead to accumulation of intramyocellular triglyceride (IMTG) and insulin resistance. We have measured mitochondrial respiration before and after a 10% low-calorie-induced weight loss in young obese women to examine the relationship...... between mitochondrial function, IMTG, and insulin resistance. Nine obese women (age, 32.3 years [SD, 3.0]; body mass index, 33.4 kg/m(2) [SD, 2.6]) completed a 53-day (SE, 3.8) very low calorie diet (VLCD) of 500 to 600 kcal/d without altering physical activity. The target of the intervention was a 10...... resistance in young obese women and do not support a direct relationship between IMTG and insulin sensitivity in young obese women during weight loss....

  5. Mitochondrial mass is inversely correlated to complete lipid oxidation in human myotubes

    DEFF Research Database (Denmark)

    Gaster, Michael

    2011-01-01

    Exercise increases while physical inactivity decrease mitochondrial content and oxidative capacity of skeletal muscles in vivo. It is unknown whether mitochondrial mass and substrate oxidation are related in non-contracting skeletal muscle. Mitochondrial mass, ATP, ADP, AMP, glucose and lipid......, basal glucose oxidation and incomplete lipid oxidation were significantly increased while complete lipid oxidation was lower. Mitochondrial mass was not correlated to glucose oxidation or incomplete lipid oxidation in human myotubes but inversely correlated to complete lipid oxidation. Thus within...... a stable energetic background, an increased mitochondrial mass in human myotubes was not positive correlated to an increased substrate oxidation as expected from skeletal muscles in vivo but surprisingly with a reduced complete lipid oxidation....

  6. A nerve stimulation method to selectively recruit smaller motor-units in rat skeletal muscle.

    Science.gov (United States)

    van Bolhuis, A I; Holsheimer, J; Savelberg, H H

    2001-05-30

    Electrical stimulation of peripheral nerve results in a motor-unit recruitment order opposite to that attained by natural neural control, i.e. from large, fast-fatiguing to progressively smaller, fatigue-resistant motor-units. Yet animal studies involving physiological exercise protocols of low intensity and long duration require minimal fatigue. The present study sought to apply a nerve stimulation method to selectively recruit smaller motor-units in rat skeletal muscle. Two pulse generators were used, independently supplying short supramaximal cathodal stimulating pulses (0.5 ms) and long subthreshold cathodal inactivating pulses (1.5 s) to the sciatic nerve. Propagation of action potentials was selectively blocked in nerve fibres of different diameter by adjusting the strength of the inactivating current. A tensile-testing machine was used to gauge isometric muscle force of the plantaris and both heads of the gastrocnemius muscle. The order of motor-unit recruitment was estimated from twitch characteristics, i.e. peak force and relaxation time. The results showed prolonged relaxation at lower twitch peak forces as the intensity of the inactivating current increased, indicating a reduction of the number of large motor-units to force production. It is shown that the nerve stimulation method described is effective in mimicking physiological muscle control.

  7. Glucose-induced insulin resistance of skeletal-muscle glucose transport and uptake

    DEFF Research Database (Denmark)

    Richter, Erik; Hansen, B F; Hansen, S A

    1988-01-01

    in the presence of glucose and insulin. The data indicate that exposure to a moderately increased glucose concentration (12 mM) leads to rapidly developing resistance of skeletal-muscle glucose transport and uptake to maximal insulin stimulation. The effect of glucose is enhanced by simultaneous insulin exposure......, whereas exposure for 5 h to insulin itself does not cause measurable resistance to maximal insulin stimulation.......The ability of glucose and insulin to modify insulin-stimulated glucose transport and uptake was investigated in perfused skeletal muscle. Here we report that perfusion of isolated rat hindlimbs for 5 h with 12 mM-glucose and 20,000 microunits of insulin/ml leads to marked, rapidly developing...

  8. (−)-EPICATECHIN IMPROVES MITOCHONDRIAL RELATED PROTEIN LEVELS AND AMELIORATES OXIDATIVE STRESS IN DYSTROPHIC DELTA SARCOGLYCAN NULL MOUSE STRIATED MUSCLE

    Science.gov (United States)

    Ramirez-Sanchez, Israel; De los Santos, Sergio; Gonzalez-Basurto, Silvia; Canto, Patricia; Mendoza-Lorenzo, Patricia; Palma-Flores, Carlos; Ceballos-Reyes, Guillermo; Villarreal, Francisco; Zentella-Dehesa, Alejandro; Coral-Vazquez, Ramon

    2014-01-01

    Muscular dystrophies (MD) are a group of heterogeneous genetic disorders characterized by progressive striated muscle wasting and degeneration. Although the genetic basis for many of these disorders has been identified, the exact mechanism for disease pathogenesis remains unclear. The presence of oxidative stress (OS) is known to contribute to the pathophysiology and severity of the MD. Mitochondrial dysfunction is observed in MD and likely represents an important determinant of increased OS. Experimental antioxidant therapies have been implemented with the aim of protecting against disease progression, but results from clinical trials have been disappointing. In this study, we explored the capacity of the cacao flavonoid (−)-epicatechin (Epi) to mitigate OS by acting as a positive regulator of mitochondrial structure/function endpoints and redox balance control systems in skeletal and cardiac muscles of dystrophic, δ-sarcoglycan (δ-SG) null mice. Wild type or δ-SG null 2.5 month old male mice were treated via oral gavage with either water (control animals) or Epi (1 mg/kg, twice/day) for 2 weeks. Results evidence a significant normalization of total protein carbonylation, recovery of reduced/oxidized glutathione (GSH/GSSG ratio) and enhanced superoxide dismutase 2, catalase and citrate synthase activities with Epi treatment. These effects were accompanied by increases in protein levels for thiolredoxin, glutathione peroxidase, superoxide dismutase 2, catalase and mitochondrial endpoints. Furthermore, we evidence decreases in heart and skeletal muscle fibrosis, accompanied with an improvement in skeletal muscle function with treatment. These results warrant the further investigation of Epi as a potential therapeutic agent to mitigate MD associated muscle degeneration. PMID:25284161

  9. Effects of experimental hyperthyroidism on protein turnover in skeletal and cardiac muscle as measured by [14C]tyrosine infusion.

    Science.gov (United States)

    Carter, W J; Benjamin, W S; Faas, F H

    1982-04-15

    The effect of T3 (3,3',5-tri-iodothyronine) on protein turnover in skeletal and cardiac muscle was measured in intact rats by means of a 6 h [14C]tyrosine-infusion technique. Treatment with 25-30 micrograms of T3/100 g body wt. daily for 4-7 days increased the fractional rate of protein synthesis in skeletal muscle. Since the fractional growth rate of the muscle was decreased or unchanged, T3 treatment increased the rate of muscle protein breakdown. These findings suggest that increased protein degradation is an important factor in decreasing skeletal-muscle mass in hyperthyroidism. In contrast with skeletal muscle, T3 treatment for 7 days caused an equivalent increase in the rate of cardiac muscle growth and protein synthesis. This suggests that hyperthyroidism does not increase protein breakdown in heart muscle as it does in skeletal muscle. The failure of T3 to increase proteolysis in heart muscle may be due to a different action on the cardiac myocyte or to systemic effects of T3 which increase cardiac work.

  10. Increased intrinsic mitochondrial function in humans with mitochondrial haplogroup H

    DEFF Research Database (Denmark)

    Larsen, Steen; Díez-Sánchez, Carmen; Rabøl, Rasmus

    2014-01-01

    and determined their mitochondrial haplogroup, mitochondrial oxidative phosphorylation capacity (OXPHOS), mitochondrial content (citrate synthase (CS)) and VO2max. Intrinsic mitochondrial function is calculated as mitochondrial OXPHOS capacity divided by mitochondrial content (CS). Haplogroup H showed a 30......% higher intrinsic mitochondrial function compared with the other haplo group U. There was no relationship between haplogroups and VO2max. In skeletal muscle from men with mitochondrial haplogroup H, an increased intrinsic mitochondrial function is present....

  11. Leucine-rich diet alters the eukaryotic translation initiation factors expression in skeletal muscle of tumour-bearing rats

    Directory of Open Access Journals (Sweden)

    Mello Maria

    2007-03-01

    Full Text Available Abstract Background Cancer-cachexia induces a variety of metabolic disorders on protein turnorver, decreasing protein synthesis and increasing protein degradation. Controversly, insulin, other hormones, and branched-chain amino acids, especially leucine, stimulate protein synthesis and modulate the activity of translation initiation factors involved in protein synthesis. Since the tumour effects are more pronounced when associated with pregnancy, ehancing muscle-wasting proteolysis, in this study, the influence of a leucine-rich diet on the protein synthesis caused by cancer were investigated. Methods Pregnant rats with or without Walker 256 tumour were distributed into six groups. During 20 days of experiment, three groups were fed with a control diet: C – pregnant control, W – tumour-bearing, and P – pair-fed, which received the same amount of food as ingested by the W group; three other groups of pregnant rats were fed a leucine-rich diet: L – pregnant leucine, WL – tumour-bearing, and PL – pair-fed, which received the same amount of food as ingested by the WL group. Results The gastrocnemius muscle of WL rats showed increased incorporation of leucine in protein compared to W rats; the leucine-rich diet also prevented the decrease in plasma insulin normally seen in W. The expression of translation initiation factors increased when tumour-bearing rats fed leucine-rich diet, with increase of ~35% for eIF2α and eIF5, ~17% for eIF4E and 20% for eIF4G; the expression of protein kinase S6K1 and protein kinase C was also highly enhanced. Conclusion The results suggest that a leucine-rich diet increased the protein synthesis in skeletal muscle in tumour-bearing rats possibly through the activation of eIF factors and/or the S6kinase pathway.

  12. Leucine-rich diet alters the eukaryotic translation initiation factors expression in skeletal muscle of tumour-bearing rats

    International Nuclear Information System (INIS)

    Ventrucci, Gislaine; Mello, Maria Alice R; Gomes-Marcondes, Maria Cristina C

    2007-01-01

    Cancer-cachexia induces a variety of metabolic disorders on protein turnorver, decreasing protein synthesis and increasing protein degradation. Controversly, insulin, other hormones, and branched-chain amino acids, especially leucine, stimulate protein synthesis and modulate the activity of translation initiation factors involved in protein synthesis. Since the tumour effects are more pronounced when associated with pregnancy, ehancing muscle-wasting proteolysis, in this study, the influence of a leucine-rich diet on the protein synthesis caused by cancer were investigated. Pregnant rats with or without Walker 256 tumour were distributed into six groups. During 20 days of experiment, three groups were fed with a control diet: C – pregnant control, W – tumour-bearing, and P – pair-fed, which received the same amount of food as ingested by the W group; three other groups of pregnant rats were fed a leucine-rich diet: L – pregnant leucine, WL – tumour-bearing, and PL – pair-fed, which received the same amount of food as ingested by the WL group. The gastrocnemius muscle of WL rats showed increased incorporation of leucine in protein compared to W rats; the leucine-rich diet also prevented the decrease in plasma insulin normally seen in W. The expression of translation initiation factors increased when tumour-bearing rats fed leucine-rich diet, with increase of ~35% for eIF2α and eIF5, ~17% for eIF4E and 20% for eIF4G; the expression of protein kinase S6K1 and protein kinase C was also highly enhanced. The results suggest that a leucine-rich diet increased the protein synthesis in skeletal muscle in tumour-bearing rats possibly through the activation of eIF factors and/or the S6kinase pathway

  13. Leucine-rich diet alters the eukaryotic translation initiation factors expression in skeletal muscle of tumour-bearing rats

    Energy Technology Data Exchange (ETDEWEB)

    Ventrucci, Gislaine [Laboratório de Nutrição e Câncer, Departamento de Fisiologia e Biofísica, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), Campinas, 13083-970, São Paulo (Brazil); Mello, Maria Alice R [Departamento de Fisiologia e Biofísica, Instituto Biociências, Universidade Estadual de São Paulo, UNESP, Rio Claro, 13506-900, São Paulo (Brazil); Gomes-Marcondes, Maria Cristina C [Laboratório de Nutrição e Câncer, Departamento de Fisiologia e Biofísica, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), Campinas, 13083-970, São Paulo (Brazil)

    2007-03-06

    Cancer-cachexia induces a variety of metabolic disorders on protein turnorver, decreasing protein synthesis and increasing protein degradation. Controversly, insulin, other hormones, and branched-chain amino acids, especially leucine, stimulate protein synthesis and modulate the activity of translation initiation factors involved in protein synthesis. Since the tumour effects are more pronounced when associated with pregnancy, ehancing muscle-wasting proteolysis, in this study, the influence of a leucine-rich diet on the protein synthesis caused by cancer were investigated. Pregnant rats with or without Walker 256 tumour were distributed into six groups. During 20 days of experiment, three groups were fed with a control diet: C – pregnant control, W – tumour-bearing, and P – pair-fed, which received the same amount of food as ingested by the W group; three other groups of pregnant rats were fed a leucine-rich diet: L – pregnant leucine, WL – tumour-bearing, and PL – pair-fed, which received the same amount of food as ingested by the WL group. The gastrocnemius muscle of WL rats showed increased incorporation of leucine in protein compared to W rats; the leucine-rich diet also prevented the decrease in plasma insulin normally seen in W. The expression of translation initiation factors increased when tumour-bearing rats fed leucine-rich diet, with increase of ~35% for eIF2α and eIF5, ~17% for eIF4E and 20% for eIF4G; the expression of protein kinase S6K1 and protein kinase C was also highly enhanced. The results suggest that a leucine-rich diet increased the protein synthesis in skeletal muscle in tumour-bearing rats possibly through the activation of eIF factors and/or the S6kinase pathway.

  14. CaMKII content affects contractile, but not mitochondrial, characteristics in regenerating skeletal muscle

    NARCIS (Netherlands)

    Eilers, W.; Jaspers, R.T.; de Haan, A.; Ferrié, C.; Valdivieso, P.; Flueck, M.

    2014-01-01

    Background: The multi-meric calcium/calmodulin-dependent protein kinase II (CaMKII) is the main CaMK in skeletal muscle and its expression increases with endurance training. CaMK family members are implicated in contraction-induced regulation of calcium handling, fast myosin type IIA expression and

  15. Leg vascular and skeletal muscle mitochondrial adaptations to aerobic high-intensity exercise training are enhanced in the early postmenopausal phase

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin; Egelund, Jon; Mandrup Jensen, Camilla Maria

    2017-01-01

    the haemodynamic response to acute exercise in matched pre- and postmenopausal women before and after 12 weeks of aerobic high intensity exercise training. Twenty premenopausal and 16 early postmenopausal (3.1 ± 0.5 [mean ± SEM] years after final menstrual period) women only separated by 4 (50 ± 0 versus 54 ± 1...... receptor α (ERRα) were increased (P training in the postmenopausal women whereas only the levels of mitochondrial complex V, eNOS, and COX-2 were increased (P aerobic......Exercise training leads to favourable adaptations within skeletal muscle; however, this effect of exercise training may be blunted in postmenopausal women due to the loss of oestrogens. Furthermore, postmenopausal women may have an impaired vascular response to acute exercise. We examined...

  16. Peripheral endocannabinoids regulate skeletal muscle development and maintenance

    Directory of Open Access Journals (Sweden)

    Dongjiao Zhao

    2010-12-01

    Full Text Available As a principal tissue responsible for insulin-mediated glucose uptake, skeletal muscle is important for whole-body health. The role of peripheral endocannabinoids as regulators of skeletal muscle metabolism has recently gained a lot of interest, as endocannabinoid system disorders could cause peripheral insulin resistance. We investigated the role of the peripheral endocannabinoid system in skeletal muscle development and maintenance. Cultures of C2C12 cells, primary satellite cells and mouse skeletal muscle single fibers were used as model systems for our studies. We found an increase in cannabinoid receptor type 1 (CB1 mRNA and endocannabinoid synthetic enzyme mRNA skeletal muscle cells during differentiation. We also found that activation of CB1 inhibited myoblast differentiation, expanded the number of satellite cells, and stimulated the fast-muscle oxidative phenotype. Our findings contribute to understanding of the role of the endocannabinoid system in skeletal muscle metabolism and muscle oxygen consumption, and also help to explain the effects of the peripheral endocannabinoid system on whole-body energy balance.

  17. Low birth weight is associated with adiposity, impaired skeletal muscle energetics, and weight loss resistance in mice

    Science.gov (United States)

    Beauchamp, Brittany; Ghosh, Sujoy; Dysart, Michael; Kanaan, Georges N.; Chu, Alphonse; Blais, Alexandre; Rajamanickam, Karunanithi; Tsai, Eve C.; Patti, Mary-Elizabeth; Harper, Mary-Ellen

    2014-01-01

    Background In utero undernutrition is associated with obesity and insulin resistance, although its effects on skeletal muscle remain poorly defined. Therefore, in the current study we explored the effects of in utero food restriction on muscle energy metabolism in mice. Methods We used an experimental mouse model system of maternal undernutrition during late pregnancy to examine offspring from undernourished dams (U) and control offspring from ad libitum fed dams (C). Weight loss of 10 wk old offspring on a 4 wk 40% calorie restricted diet was also followed. Experimental approaches included bioenergetic analyses in isolated mitochondria, intact (permeabilized) muscle and at the whole body level. Results U have increased adiposity and decreased glucose tolerance compared to C. Strikingly, when U are put on a 40% calorie restricted diet they lose half as much weight as calorie restricted controls. Mitochondria from muscle overall from U had decreased coupled (state 3) and uncoupled (state 4) respiration and increased maximal respiration compared to C. Mitochondrial yield was lower in U than C. In permeabilized fiber preparations from mixed fiber type muscle U had decreased mitochondrial content and decreased adenylate free leak respiration, fatty acid oxidative capacity, and state 3 respiratory capacity through complex I. Fiber maximal oxidative phosphorylation capacity did not differ between U and C but was decreased with calorie restriction. Conclusions Our results reveal that in utero undernutrition alters metabolic physiology through a profound effect on skeletal muscle energetics and blunts response to a hypocaloric diet in adulthood. We propose that mitochondrial dysfunction links undernutrition in utero with metabolic disease in adulthood. PMID:25091727

  18. The organization of the Golgi complex and microtubules in skeletal muscle is fiber type-dependent

    DEFF Research Database (Denmark)

    Ralston, E; Lu, Z; Ploug, Thorkil

    1999-01-01

    Skeletal muscle has a nonconventional Golgi complex (GC), the organization of which has been a subject of controversy in the past. We have now examined the distribution of the GC by immunofluorescence and immunogold electron microscopy in whole fibers from different rat muscles, both innervated a...

  19. Structure–function relationship of skeletal muscle provides inspiration for design of new artificial muscle

    International Nuclear Information System (INIS)

    Gao, Yingxin; Zhang, Chi

    2015-01-01

    A variety of actuator technologies have been developed to mimic biological skeletal muscle that generates force in a controlled manner. Force generation process of skeletal muscle involves complicated biophysical and biochemical mechanisms; therefore, it is impossible to replace biological muscle. In biological skeletal muscle tissue, the force generation of a muscle depends not only on the force generation capacity of the muscle fiber, but also on many other important factors, including muscle fiber type, motor unit recruitment, architecture, structure and morphology of skeletal muscle, all of which have significant impact on the force generation of the whole muscle or force transmission from muscle fibers to the tendon. Such factors have often been overlooked, but can be incorporated in artificial muscle design, especially with the discovery of new smart materials and the development of innovative fabrication and manufacturing technologies. A better understanding of the physiology and structure–function relationship of skeletal muscle will therefore benefit the artificial muscle design. In this paper, factors that affect muscle force generation are reviewed. Mathematical models used to model the structure–function relationship of skeletal muscle are reviewed and discussed. We hope the review will provide inspiration for the design of a new generation of artificial muscle by incorporating the structure–function relationship of skeletal muscle into the design of artificial muscle. (topical review)

  20. Structure-function relationship of skeletal muscle provides inspiration for design of new artificial muscle

    Science.gov (United States)

    Gao, Yingxin; Zhang, Chi

    2015-03-01

    A variety of actuator technologies have been developed to mimic biological skeletal muscle that generates force in a controlled manner. Force generation process of skeletal muscle involves complicated biophysical and biochemical mechanisms; therefore, it is impossible to replace biological muscle. In biological skeletal muscle tissue, the force generation of a muscle depends not only on the force generation capacity of the muscle fiber, but also on many other important factors, including muscle fiber type, motor unit recruitment, architecture, structure and morphology of skeletal muscle, all of which have significant impact on the force generation of the whole muscle or force transmission from muscle fibers to the tendon. Such factors have often been overlooked, but can be incorporated in artificial muscle design, especially with the discovery of new smart materials and the development of innovative fabrication and manufacturing technologies. A better understanding of the physiology and structure-function relationship of skeletal muscle will therefore benefit the artificial muscle design. In this paper, factors that affect muscle force generation are reviewed. Mathematical models used to model the structure-function relationship of skeletal muscle are reviewed and discussed. We hope the review will provide inspiration for the design of a new generation of artificial muscle by incorporating the structure-function relationship of skeletal muscle into the design of artificial muscle.

  1. Cytoskeleton, L-type Ca2+ and stretch activated channels in injured skeletal muscle

    Directory of Open Access Journals (Sweden)

    Fabio Francini

    2013-07-01

    Full Text Available The extra-sarcomeric cytoskeleton (actin microfilaments and anchoring proteins is involved in maintaining the sarco-membrane stiffness and integrity and in turn the mechanical stability and function of the intra- and sub-sarcoplasmic proteins. Accordingly, it regulates Ca2+ entry through the L-type Ca2+ channels and the mechano-sensitivity of the stretch activated channels (SACs. Moreover, being intra-sarcomeric cytoskeleton bound to costameric proteins and other proteins of the sarcoplasma by intermediate filaments, as desmin, it integrates the properties of the sarcolemma with the skeletal muscle fibres contraction. The aim of this research was to compare the cytoskeleton, SACs and the ECC alterations in two different types of injured skeletal muscle fibres: by muscle denervation and mechanical overload (eccentric contraction. Experiments on denervation were made in isolated Soleus muscle of male Wistar rats; forced eccentric-contraction (EC injury was achieved in Extensor Digitorum Longus muscles of Swiss mice. The method employed conventional intracellular recording with microelectrodes inserted in a single fibre of an isolated skeletal muscle bundle. The state of cytoskeleton was evaluated by recording SAC currents and by evaluating the resting membrane potential (RMP value determined in current-clamp mode. The results demonstrated that in both injured skeletal muscle conditions the functionality of L-type Ca2+ current, ICa, was affected. In parallel, muscle fibres showed an increase of the resting membrane permeability and of the SAC current. These issues, together with a more depolarized RMP are an index of altered cytoskeleton. In conclusion, we found a symilar alteration of ICa, SAC and cytoskeleton in both injured skeletal muscle conditions.

  2. Ginsenoside Rb1 improves postoperative fatigue syndrome by reducing skeletal muscle oxidative stress through activation of the PI3K/Akt/Nrf2 pathway in aged rats.

    Science.gov (United States)

    Zhuang, Cheng-Le; Mao, Xiang-Yu; Liu, Shu; Chen, Wei-Zhe; Huang, Dong-Dong; Zhang, Chang-Jing; Chen, Bi-Cheng; Shen, Xian; Yu, Zhen

    2014-10-05

    Ginsenoside Rb1 is reported to possess anti-fatigue activity, but the mechanisms remain unknown. The aim of this study was to investigate the molecular mechanisms responsible for the anti-fatigue effect of ginsenoside Rb1 on postoperative fatigue syndrome induced by major small intestinal resection (MSIR) in aged rat. Aged rats with MSIR were administrated with ginsenoside Rb1 (15 mg/kg) once a day from 3 days before surgery to the day of sacrifice, or with saline as corresponding controls. Rats without MSIR but going through the same surgery procedure were administrated with saline as blank controls. Anti-fatigue effect was assessed by an open field test; superoxide dismutase, reactive oxygen species and malondialdehyde in skeletal muscle were determined. The mRNA levels of Akt2 and Nrf2 in skeletal muscle were measured by real-time quantitative PCR. The activation of Akt and Nrf2 was examined by western blot and immunohistofluorescence. Our results revealed that ginsenoside Rb1 significantly increased the journey and the rearing frequency, decreased the time of rest in aged rats with MSIR. In addition, ginsenoside Rb1 significantly reduced reactive oxygen species and malondialdehyde release and increased the superoxide dismutase activity of skeletal muscle in aged rats with MSIR. Ginsenoside Rb1 also increased the expression of Akt2 and Nrf2 mRNA, up-regulated Akt phosphorylation and Nrf2 nuclear translocation. These findings indicate that ginsenoside Rb1 has an anti-fatigue effect on postoperative fatigue syndrome in aged rat, and the mechanism possibly involves activation of the PI3K/Akt pathway with subsequent Nrf2 nuclear translocation and induction of antioxidant enzymes. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Mitochondrial-Targeted Antioxidant Maintains Blood Flow, Mitochondrial Function, and Redox Balance in Old Mice Following Prolonged Limb Ischemia

    Directory of Open Access Journals (Sweden)

    Shunsuke Miura

    2017-09-01

    Full Text Available Aging is a major factor in the decline of limb blood flow with ischemia. However, the underlying mechanism remains unclear. We investigated the role of mitochondrial reactive oxygen species (ROS with regard to limb perfusion recovery in aging during ischemia. We performed femoral artery ligation in young and old mice with or without treatment with a scavenger of mitochondrial superoxide, MitoTEMPO (180 μg/kg/day, from pre-operative day 7 to post-operative day (POD 21 infusion using an implanted mini-pump. The recoveries of cutaneous blood flow in the ischemic hind limb were lower in old mice than in young mice but were improved in MitoTEMPO-treated old mice. Mitochondrial DNA damage appeared in ischemic aged muscles but was eliminated by MitoTEMPO treatment. For POD 2, MitoTEMPO treatment suppressed the expression of p53 and the ratio of Bax/Bcl2 and upregulated the expression of hypoxia-inducible factor-1α (HIF-1α and vascular endothelial growth factor (VEGF in ischemic aged skeletal muscles. For POD 21, MitoTEMPO treatment preserved the expression of PGC-1α in ischemic aged skeletal muscle. The ischemic soleus of old mice showed a lower mitochondrial respiratory control ratio in POD 21 compared to young mice, which was recovered in MitoTEMPO-treated old mice. Scavenging of mitochondrial superoxide attenuated mitochondrial DNA damage and preserved the mitochondrial respiration, in addition to suppression of the expression of p53 and preservation of the expression of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α in ischemic skeletal muscles with aging. Resolution of excessive mitochondrial superoxide could be an effective therapy to recover blood flow of skeletal muscle during ischemia in senescence.

  4. Transcriptome-wide RNA sequencing analysis of rat skeletal muscle feed arteries. II. Impact of exercise training in obesity

    Science.gov (United States)

    Jenkins, Nathan T.; Thorne, Pamela K.; Martin, Jeffrey S.; Rector, R. Scott; Davis, J. Wade; Laughlin, M. Harold

    2014-01-01

    We employed next-generation RNA sequencing (RNA-Seq) technology to determine the extent to which exercise training alters global gene expression in skeletal muscle feed arteries and aortic endothelial cells of obese Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Transcriptional profiles of the soleus and gastrocnemius muscle feed arteries (SFA and GFA, respectively) and aortic endothelial cell-enriched samples from rats that underwent an endurance exercise training program (EndEx; n = 12) or a interval sprint training program (IST; n = 12) or remained sedentary (Sed; n = 12) were examined. In response to EndEx, there were 39 upregulated (e.g., MANF) and 20 downregulated (e.g., ALOX15) genes in SFA and 1 upregulated (i.e., Wisp2) and 1 downregulated (i.e., Crem) gene in GFA [false discovery rate (FDR) exercise programs. Expression of only two genes (Tubb2b and Slc9a3r2) was altered (i.e., increased) by exercise in all three arteries. The finding that both EndEx and IST produced greater transcriptional changes in the SFA compared with the GFA is intriguing when considering the fact that treadmill bouts of exercise are associated with greater relative increases in blood flow to the gastrocnemius muscle compared with the soleus muscle. PMID:24408995

  5. Chemotherapy inhibits skeletal muscle ubiquitin-proteasome-dependent proteolysis.

    Science.gov (United States)

    Tilignac, Thomas; Temparis, Sandrine; Combaret, Lydie; Taillandier, Daniel; Pouch, Marie-Noëlle; Cervek, Matjaz; Cardenas, Diana M; Le Bricon, Thierry; Debiton, Eric; Samuels, Susan E; Madelmont, Jean-Claude; Attaix, Didier

    2002-05-15

    Chemotherapy has cachectic effects, but it is unknown whether cytostatic agents alter skeletal muscle proteolysis. We hypothesized that chemotherapy-induced alterations in protein synthesis should result in the increased incidence of abnormal proteins, which in turn should stimulate ubiquitin-proteasome-dependent proteolysis. The effects of the nitrosourea cystemustine were investigated in skeletal muscles from both healthy and colon 26 adenocarcinoma-bearing mice, an appropriate model for testing the impact of cytostatic agents. Muscle wasting was seen in both groups of mice 4 days after a single cystemustine injection, and the drug further increased the loss of muscle proteins already apparent in tumor-bearing animals. Cystemustine cured the tumor-bearing mice with 100% efficacy. Surprisingly, within 11 days of treatment, rates of muscle proteolysis progressively decreased below basal levels observed in healthy control mice and contributed to the cessation of muscle wasting. Proteasome-dependent proteolysis was inhibited by mechanisms that include reduced mRNA levels for 20S and 26S proteasome subunits, decreased protein levels of 20S proteasome subunits and the S14 non-ATPase subunit of the 26S proteasome, and impaired chymotrypsin- and trypsin-like activities of the enzyme. A combination of cisplatin and ifosfamide, two drugs that are widely used in the treatment of cancer patients, also depressed the expression of proteasomal subunits in muscles from rats bearing the MatB adenocarcinoma below basal levels. Thus, a down-regulation of ubiquitin-proteasome-dependent proteolysis is observed with various cytostatic agents and contributes to reverse the chemotherapy-induced muscle wasting.

  6. Regenerated rat skeletal muscle after periodic contusions

    Directory of Open Access Journals (Sweden)

    V.B. Minamoto

    2001-11-01

    Full Text Available In the present study we evaluated the morphological aspect and changes in the area and incidence of muscle fiber types of long-term regenerated rat tibialis anterior (TA muscle previously submitted to periodic contusions. Animals received eight consecutive traumas: one trauma per week, for eight weeks, and were evaluated one (N = 8 and four (N = 9 months after the last contusion. Serial cross-sections were evaluated by toluidine blue staining, acid phosphatase and myosin ATPase reactions. The weight of injured muscles was decreased compared to the contralateral intact one (one month: 0.77 ± 0.15 vs 0.91 ± 0.09 g, P = 0.03; four months: 0.79 ± 0.14 vs 1.02 ± 0.07 g, P = 0.0007, respectively and showed abundant presence of split fibers and fibers with centralized nuclei, mainly in the deep portion. Damaged muscles presented a higher incidence of undifferentiated fibers when compared to the intact one (one month: 3.4 ± 2.1 vs 0.5 ± 0.3%, P = 0.006; four months: 2.3 ± 1.6 vs 0.3 ± 0.3%, P = 0.007, respectively. Injured TA evaluated one month later showed a decreased area of muscle fibers when compared to the intact one (P = 0.003. Thus, we conclude that: a muscle fibers were damaged mainly in the deep portion, probably because they were compressed against the tibia; b periodic contusions in the TA muscle did not change the percentage of type I and II muscle fibers; c periodically injured TA muscles took four months to reach a muscle fiber area similar to that of the intact muscle.

  7. Omega-3 Fatty Acids and Skeletal Muscle Health

    Directory of Open Access Journals (Sweden)

    Stewart Jeromson

    2015-11-01

    Full Text Available Skeletal muscle is a plastic tissue capable of adapting and mal-adapting to physical activity and diet. The response of skeletal muscle to adaptive stimuli, such as exercise, can be modified by the prior nutritional status of the muscle. The influence of nutrition on skeletal muscle has the potential to substantially impact physical function and whole body metabolism. Animal and cell based models show that omega-3 fatty acids, in particular those of marine origin, can influence skeletal muscle metabolism. Furthermore, recent human studies demonstrate that omega-3 fatty acids of marine origin can influence the exercise and nutritional response of skeletal muscle. These studies show that the prior omega-3 status influences not only the metabolic response of muscle to nutrition, but also the functional response to a period of exercise training. Omega-3 fatty acids of marine origin therefore have the potential to alter the trajectory of a number of human diseases including the physical decline associated with aging. We explore the potential molecular mechanisms by which omega-3 fatty acids may act in skeletal muscle, considering the n-3/n-6 ratio, inflammation and lipidomic remodelling as possible mechanisms of action. Finally, we suggest some avenues for further research to clarify how omega-3 fatty acids may be exerting their biological action in skeletal muscle.

  8. Characterization of the equine skeletal muscle transcriptome identifies novel functional responses to exercise training.

    LENUS (Irish Health Repository)

    McGivney, Beatrice A

    2010-01-01

    BACKGROUND: Digital gene expression profiling was used to characterize the assembly of genes expressed in equine skeletal muscle and to identify the subset of genes that were differentially expressed following a ten-month period of exercise training. The study cohort comprised seven Thoroughbred racehorses from a single training yard. Skeletal muscle biopsies were collected at rest from the gluteus medius at two time points: T(1) - untrained, (9 +\\/- 0.5 months old) and T(2) - trained (20 +\\/- 0.7 months old). RESULTS: The most abundant mRNA transcripts in the muscle transcriptome were those involved in muscle contraction, aerobic respiration and mitochondrial function. A previously unreported over-representation of genes related to RNA processing, the stress response and proteolysis was observed. Following training 92 tags were differentially expressed of which 74 were annotated. Sixteen genes showed increased expression, including the mitochondrial genes ACADVL, MRPS21 and SLC25A29 encoded by the nuclear genome. Among the 58 genes with decreased expression, MSTN, a negative regulator of muscle growth, had the greatest decrease.Functional analysis of all expressed genes using FatiScan revealed an asymmetric distribution of 482 Gene Ontology (GO) groups and 18 KEGG pathways. Functional groups displaying highly significant (P < 0.0001) increased expression included mitochondrion, oxidative phosphorylation and fatty acid metabolism while functional groups with decreased expression were mainly associated with structural genes and included the sarcoplasm, laminin complex and cytoskeleton. CONCLUSION: Exercise training in Thoroughbred racehorses results in coordinate changes in the gene expression of functional groups of genes related to metabolism, oxidative phosphorylation and muscle structure.

  9. Influence of endurance training on skeletal muscle mitophagy regulatory proteins in type 2 diabetic men.

    Science.gov (United States)

    Brinkmann, Christian; Przyklenk, Axel; Metten, Alexander; Schiffer, Thorsten; Bloch, Wilhelm; Brixius, Klara; Gehlert, Sebastian

    2017-11-01

    Mitophagy is a form of autophagy for the elimination of mitochondria. Mitochondrial content and function are reduced in the skeletal muscle of patients with type 2 diabetes mellitus (T2DM). Physical training has been shown to restore mitochondrial capacity in T2DM patients, but the role of mitophagy has not been examined in this context. This study analyzes the impact of a 3-month endurance training on important skeletal muscle mitophagy regulatory proteins and oxidative phosphorylation (OXPHOS) complexes in T2DM patients. Muscle biopsies were obtained from eight overweight/obese T2DM men (61±10 years) at T1 (6 weeks pre-training), T2 (1 week pre-training), and T3 (3 to 4 days post-training). Protein contents were determined by Western blotting. The training increased mitochondrial complex II significantly (T2-T3: +29%, p = 0.037). The protein contents of mitophagy regulatory proteins (phosphorylated form of forkhead box O3A (pFOXO3A), mitochondrial E3 ubiquitin protein ligase-1 (MUL1), Bcl-2/adenovirus E1B 19-kD interacting protein-3 (BNIP3), microtubule-associated protein 1 light chain-3B (the ratio LC3B-II/LC3B-I was determined)) did not differ significantly between T1, T2, and T3. The results imply that training-induced changes in OXPHOS subunits (significant increase in complex II) are not accompanied by changes in mitophagy regulatory proteins in T2DM men. Future studies should elucidate whether acute exercise might affect mitophagic processes in T2DM patients (and whether a transient regulation of mitophagy regulatory proteins is evident) to fully clarify the role of physical activity and mitophagy for mitochondrial health in this particular patient group.

  10. [Autophagy-lysosome pathway in skeletal muscle of diabetic nephropathy rats and the effect of low-protein diet plus α-keto acids on it].

    Science.gov (United States)

    Huang, Juan; Yuan, Wei-jie; Wang, Jia-lin; Gu, Li-jie; Yin, Jun; Dong, Ting; Bao, Jin-fang; Tang, Zhi-huan

    2013-11-26

    To explore the regulation of autophagy-lysosome pathway (ALP) in skeletal muscle of diabetic nephropathy and examine the effect of low protein diet plus α-keto acid on ALP. A total of 45 24-week-old Goto-Kakizaki rats were randomized to receive normal protein (22%) diet (NPD), low-protein (6%) diet (LPD) or low-protein (5%) plus α-keto acids (1%) diet (Keto) (n = 15 each). Wistar control rats had a normal protein diet. The mRNA and protein levels of ALP markers LC3B, Bnip3, Cathepsin L in soleus muscle were evaluated at 48 weeks. Electron microscopy was used to confirm the changes of autophagy. Compared with CTL group, the mRNA levels of LC3B, Bnip3, Cathepsin L in soleus muscle of rats on NPD were higher, and protein levels of LC3B-I, LC3B-II, Bnip3, Cathepsin L in soleus muscle of rats on NPD also higher than CTL group (0.82 ± 0.33 vs 0.25 ± 0.07, 0.76 ± 0.38 vs 0.20 ± 0.12, 1.25 ± 0.30 vs 0.56 ± 0.19, 1.29 ± 0.40 vs 0.69 ± 0.20). The mRNA levels of LC3B, Bnip3 and Cathepsin L in LPD group were slightly lower, compared with NPD group. However there was no statistical significance. Similarly the protein levels of LC3B-I, LC3B-II, Bnip3 and Cathepsin L in LPD group were slightly lower with no statistical significance. In contrast, the mRNA levels of LC3B, Bnip3 and Cathepsin L were greatly lower in Keto group in comparison with NPD and LPD. And protein levels of LC3B-I, LC3B-II, Bnip3 and Cathepsin L were also greatly lower in Keto group in comparison with NPD and LPD. Additionally, autophagosome or auto-lysosome was found in NPD and LPD groups by electron microscopy. ALP is activated in skeletal muscle of diabetic nephropathy rats. And low protein plus α-keto acid decrease the activation of ALP and improve muscle wasting.

  11. Effects of hypertonic dextrose on injured rat skeletal muscles.

    Science.gov (United States)

    Kunduracioglu, Burak; Ulkar, Bulent; Sabuncuoglu, Bizden T; Can, Belgin; Bayrakci, Kenan

    2006-04-01

    Histological examination of proliferative therapy effects on the healing process of muscular injury. We performed this study between March and August 2002 at Ankara University, School of Medicine, Laboratory of Animal Experiments, Ankara, Turkey. We used an experimental animal model by conducting a standardized cut injury of the gastrocnemius muscle in 30 adult male albino rats, which we divided into 2 groups; proliferative therapy group and control group. We evaluated the injured rat muscles by light microscopy on the fifth, eight, and twelfth day of injury. The muscular regeneration process began at day 5 in both the control and proliferative therapy groups. The proliferative therapy group revealed a prominent inflammatory reaction, fibroblast migration, and necrosis with accompanying regeneration and excessive connective tissue formation. We cannot consider proliferative therapy an appropriate treatment modality for muscular injuries, unless there is evidence of normal muscle physiology and biomechanics post traumatically.

  12. Guava leaf extracts promote glucose metabolism in SHRSP.Z-Leprfa/Izm rats by improving insulin resistance in skeletal muscle.

    Science.gov (United States)

    Guo, Xiangyu; Yoshitomi, Hisae; Gao, Ming; Qin, Lingling; Duan, Ying; Sun, Wen; Xu, Tunhai; Xie, Peifeng; Zhou, Jingxin; Huang, Liansha; Liu, Tonghua

    2013-03-01

    Metabolic syndrome (MS) and type 2 diabetes mellitus (T2DM) have been associated with insulin-resistance; however, the effective therapies in improving insulin sensitivity are limited. This study is aimed at investigating the effect of Guava Leaf (GL) extracts on glucose tolerance and insulin resistance in SHRSP.Z-Leprfa/Izm rats (SHRSP/ZF), a model of spontaneously metabolic syndrome. Male rats at 7 weeks of age were administered with vehicle water or treated by gavage with 2 g/kg GL extracts daily for six weeks, and their body weights, water and food consumption, glucose tolerance, and insulin resistance were measured. Compared with the controls, treatment with GL extracts did not modulate the amounts of water and food consumption, but significantly reduced the body weights at six weeks post treatment. Treatment with GL extracts did not alter the levels of fasting plasma glucose and insulin, but significantly reduced the levels of plasma glucose at 60 and 120 min post glucose challenge, also reduced the values of AUC and quantitative insulin sensitivity check index (QUICKI) at 42 days post treatment. Furthermore, treatment with GL extracts promoted IRS-1, AKT, PI3Kp85 expression, then IRS-1, AMKP, and AKT308, but not AKT473, phosphorylation, accompanied by increasing the ratios of membrane to total Glut 4 expression and adiponectin receptor 1 transcription in the skeletal muscles. These data indicated that GL extracts improved glucose metabolism and insulin sensitivity in the skeletal muscles of rats by modulating the insulin-related signaling.

  13. Passive Repetitive Stretching for a Short Duration within a Week Increases Myogenic Regulatory Factors and Myosin Heavy Chain mRNA in Rats' Skeletal Muscles

    Directory of Open Access Journals (Sweden)

    Yurie Kamikawa

    2013-01-01

    Full Text Available Stretching is a stimulation of muscle growth. Stretching for hours or days has an effect on muscle hypertrophy. However, differences of continuous stretching and repetitive stretching to affect muscle growth are not well known. To clarify the difference of continuous and repetitive stretching within a short duration, we investigated the gene expression of muscle-related genes on stretched skeletal muscles. We used 8-week-old male Wistar rats ( for this study. Animals medial gastrocnemius muscle was stretched continuously or repetitively for 15 min daily and 4 times/week under anesthesia. After stretching, muscles were removed and total RNA was extracted. Then, reverse transcriptional quantitative real-time PCR was done to evaluate the mRNA expression of MyoD, myogenin, and embryonic myosin heavy chain (MyHC. Muscles, either stretched continuously or repetitively, increased mRNA expression of MyoD, myogenin, and embryonic MyHC more than unstretched muscles. Notably, repetitive stretching resulted in more substantial effects on embryonic MyHC gene expression than continuous stretching. In conclusion, passive stretching for a short duration within a week is effective in increasing myogenic factor expression, and repetitive stretching had more effects than continuous stretching for skeletal muscle on muscle growth. These findings are applicable in clinical muscle-strengthening therapy.

  14. 18F-fluorodeoxyglucose accumulation in the heart, brain and skeletal muscle of rats; the influence of time after injection, depressed lipid metabolism and glucose-insulin

    International Nuclear Information System (INIS)

    Kasalicky, J.; Konopkova, M.; Melichar, F.

    2001-01-01

    To study the effect of lipid depressing drugs on 18 FDG myocardial concentration. The changes of 18 FDG uptake in myocardium, brain and skeletal muscle of rats were compared as influenced by acipimox, tyloxapol and glucose with insulin. 5.55 MBq of 18 FDG were administered to Wistar rats. Control rats were killed 15, 30, 45 and 60 minutes following intravenous injection and the radioactivity concentration (cpm/g of tissue) in relation to injected cpm was determined in a well crystal adjusted to 511 KeV in order to check the time of maximal 18 FDG tissue uptake. The radioactivity in myocardium, skeletal muscle and brain in intact animals was compared with that of rats treated with tyloxapol (tritton WR 1339, 125 mg intravenously immediately before 18 FDG injection), acipimox (nicotinic acid derivative, 25 mg by stomach cannula 15 minutes before 18 FDG), or glucose with insulin (intravenous injection of 0.04 g and 0.04 UI immediately before 18 FDG). The animals were killed 45 minutes following 18 FDG injection. Tyloxapol and acipimox significantly elevated myocardial 18 FDG concentration (tyloxapol +37% and acipimox +48%), but the increase in 18 FDG concentration after glucose and insulin was slight and insignificant. The changes in skeletal muscle after lipid depressing agents were quite contrasting; the decrease in 18 FDG concentration was -74% after tyloxapol and -44% following acipimox administration. The accumulation of 18 FDG in brain was not influenced markedly by the drugs used or by glucose with insulin. The highest 18 FDG uptake in myocardium could be achieved by depressing the lipid metabolism and not by administration of glucose with insulin only. A marked increase in glucose accumulation in myocardium is not possible without previous shift from the utilisation of fatty acids. This finding is fully in agreement with present knowledge about energetic metabolism of myocardium. (author)

  15. Quantification of skeletal muscle mitochondrial function by 31P magnetic resonance spectroscopy techniques : A quantitative review

    NARCIS (Netherlands)

    Kemp, G.J.; Ahmad, R.E.; Nicolay, K.; Prompers, J.J.

    2015-01-01

    Magnetic resonance spectroscopy (MRS) can give information about cellular metabolism in vivo which is difficult to obtain in other ways. In skeletal muscle, non-invasive 31P MRS measurements of the post-exercise recovery kinetics of pH, [PCr], [Pi] and [ADP] contain valuable information about muscle

  16. Lentivirus administration to rat muscle provides efficient sustained expression of erythropoietin

    NARCIS (Netherlands)

    Seppen, J.; Barry, S. C.; Harder, B.; Osborne, W. R.

    2001-01-01

    A lentivirus pseudotyped with vesicular stomatitis virus G protein (VSV-G) encoding rat erythropoietin (EPO) complementary DNA was administered to rat skeletal muscle and red blood cell production was serially monitored. After a single intramuscular injection hematocrit values increased and reached

  17. Hydrogen peroxide production regulates the mitochondrial function in insulin resistant muscle cells: effect of catalase overexpression.

    Science.gov (United States)

    Barbosa, Marina R; Sampaio, Igor H; Teodoro, Bruno G; Sousa, Thais A; Zoppi, Claudio C; Queiroz, André L; Passos, Madla A; Alberici, Luciane C; Teixeira, Felipe R; Manfiolli, Adriana O; Batista, Thiago M; Cappelli, Ana Paula Gameiro; Reis, Rosana I; Frasson, Danúbia; Kettelhut, Isis C; Parreiras-e-Silva, Lucas T; Costa-Neto, Claudio M; Carneiro, Everardo M; Curi, Rui; Silveira, Leonardo R

    2013-10-01

    The mitochondrial redox state plays a central role in the link between mitochondrial overloading and insulin resistance. However, the mechanism by which the ROS induce insulin resistance in skeletal muscle cells is not completely understood. We examined the association between mitochondrial function and H2O2 production in insulin resistant cells. Our hypothesis is that the low mitochondrial oxygen consumption leads to elevated ROS production by a mechanism associated with reduced PGC1α transcription and low content of phosphorylated CREB. The cells were transfected with either the encoded sequence for catalase overexpression or the specific siRNA for catalase inhibition. After transfection, myotubes were incubated with palmitic acid (500μM) and the insulin response, as well as mitochondrial function and fatty acid metabolism, was determined. The low mitochondrial oxygen consumption led to elevated ROS production by a mechanism associated with β-oxidation of fatty acids. Rotenone was observed to reduce the ratio of ROS production. The elevated H2O2 production markedly decreased the PGC1α transcription, an effect that was accompanied by a reduced phosphorylation of Akt and CREB. The catalase transfection prevented the reduction in the phosphorylated level of Akt and upregulated the levels of phosphorylated CREB. The mitochondrial function was elevated and H2O2 production reduced, thus increasing the insulin sensitivity. The catalase overexpression improved mitochondrial respiration protecting the cells from fatty acid-induced, insulin resistance. This effect indicates that control of hydrogen peroxide production regulates the mitochondrial respiration preventing the insulin resistance in skeletal muscle cells by a mechanism associated with CREB phosphorylation and β-oxidation of fatty acids. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Metformin-treated patients with type 2 diabetes have normal mitochondrial complex I respiration

    DEFF Research Database (Denmark)

    Larsen, Steen; Rabøl, R; Hansen, C N

    2012-01-01

    The glucose-lowering drug metformin has been shown to inhibit complex I of the mitochondrial electron transport chain in skeletal muscle. To investigate this effect in vivo we studied skeletal muscle mitochondrial respiratory capacity and content from patients with type 2 diabetes treated...

  19. Skeletal Muscle-specific G Protein-coupled Receptor Kinase 2 Ablation Alters Isolated Skeletal Muscle Mechanics and Enhances Clenbuterol-stimulated Hypertrophy.

    Science.gov (United States)

    Woodall, Benjamin P; Woodall, Meryl C; Luongo, Timothy S; Grisanti, Laurel A; Tilley, Douglas G; Elrod, John W; Koch, Walter J

    2016-10-14

    GRK2, a G protein-coupled receptor kinase, plays a critical role in cardiac physiology. Adrenergic receptors are the primary target for GRK2 activity in the heart; phosphorylation by GRK2 leads to desensitization of these receptors. As such, levels of GRK2 activity in the heart directly correlate with cardiac contractile function. Furthermore, increased expression of GRK2 after cardiac insult exacerbates injury and speeds progression to heart failure. Despite the importance of this kinase in both the physiology and pathophysiology of the heart, relatively little is known about the role of GRK2 in skeletal muscle function and disease. In this study we generated a novel skeletal muscle-specific GRK2 knock-out (KO) mouse (MLC-Cre:GRK2 fl/fl ) to gain a better understanding of the role of GRK2 in skeletal muscle physiology. In isolated muscle mechanics testing, GRK2 ablation caused a significant decrease in the specific force of contraction of the fast-twitch extensor digitorum longus muscle yet had no effect on the slow-twitch soleus muscle. Despite these effects in isolated muscle, exercise capacity was not altered in MLC-Cre:GRK2 fl/fl mice compared with wild-type controls. Skeletal muscle hypertrophy stimulated by clenbuterol, a β 2 -adrenergic receptor (β 2 AR) agonist, was significantly enhanced in MLC-Cre:GRK2 fl/fl mice; mechanistically, this seems to be due to increased clenbuterol-stimulated pro-hypertrophic Akt signaling in the GRK2 KO skeletal muscle. In summary, our study provides the first insights into the role of GRK2 in skeletal muscle physiology and points to a role for GRK2 as a modulator of contractile properties in skeletal muscle as well as β 2 AR-induced hypertrophy. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  20. Skeletal Muscle-specific G Protein-coupled Receptor Kinase 2 Ablation Alters Isolated Skeletal Muscle Mechanics and Enhances Clenbuterol-stimulated Hypertrophy*

    Science.gov (United States)

    Woodall, Benjamin P.; Woodall, Meryl C.; Luongo, Timothy S.; Grisanti, Laurel A.; Tilley, Douglas G.; Elrod, John W.; Koch, Walter J.

    2016-01-01

    GRK2, a G protein-coupled receptor kinase, plays a critical role in cardiac physiology. Adrenergic receptors are the primary target for GRK2 activity in the heart; phosphorylation by GRK2 leads to desensitization of these receptors. As such, levels of GRK2 activity in the heart directly correlate with cardiac contractile function. Furthermore, increased expression of GRK2 after cardiac insult exacerbates injury and speeds progression to heart failure. Despite the importance of this kinase in both the physiology and pathophysiology of the heart, relatively little is known about the role of GRK2 in skeletal muscle function and disease. In this study we generated a novel skeletal muscle-specific GRK2 knock-out (KO) mouse (MLC-Cre:GRK2fl/fl) to gain a better understanding of the role of GRK2 in skeletal muscle physiology. In isolated muscle mechanics testing, GRK2 ablation caused a significant decrease in the specific force of contraction of the fast-twitch extensor digitorum longus muscle yet had no effect on the slow-twitch soleus muscle. Despite these effects in isolated muscle, exercise capacity was not altered in MLC-Cre:GRK2fl/fl mice compared with wild-type controls. Skeletal muscle hypertrophy stimulated by clenbuterol, a β2-adrenergic receptor (β2AR) agonist, was significantly enhanced in MLC-Cre:GRK2fl/fl mice; mechanistically, this seems to be due to increased clenbuterol-stimulated pro-hypertrophic Akt signaling in the GRK2 KO skeletal muscle. In summary, our study provides the first insights into the role of GRK2 in skeletal muscle physiology and points to a role for GRK2 as a modulator of contractile properties in skeletal muscle as well as β2AR-induced hypertrophy. PMID:27566547