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Sample records for contracting rat skeletal

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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.

  6. 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

  7. 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.

  8. 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...

  9. 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.

  10. Contraction-associated translocation of protein kinase C in rat skeletal muscle

    DEFF Research Database (Denmark)

    Richter, Erik; Cleland, P J; Rattigan, S

    1987-01-01

    Electrical stimulation of the sciatic nerve of the anaesthetized rat in vivo led to a time-dependent translocation of protein kinase C from the muscle cytosol to the particulate fraction. Maximum activity of protein kinase C in the particulate fraction occurred after 2 min of intermittent short...... tetanic contractions of the gastrocnemius-plantaris-soleus muscle group and coincided with the loss of activity from the cytosol. Translocation of protein kinase C may imply a role for this kinase in contraction-initiated changes in muscle metabolism....

  11. 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.

  12. Endurance training facilitates myoglobin desaturation during muscle contraction in rat skeletal muscle.

    Science.gov (United States)

    Takakura, Hisashi; Furuichi, Yasuro; Yamada, Tatsuya; Jue, Thomas; Ojino, Minoru; Hashimoto, Takeshi; Iwase, Satoshi; Hojo, Tatsuya; Izawa, Tetsuya; Masuda, Kazumi

    2015-03-24

    At onset of muscle contraction, myoglobin (Mb) immediately releases its bound O2 to the mitochondria. Accordingly, intracellular O2 tension (PmbO2) markedly declines in order to increase muscle O2 uptake (mVO2). However, whether the change in PmbO2 during muscle contraction modulates mVO2 and whether the O2 release rate from Mb increases in endurance-trained muscles remain unclear. The purpose of this study was, therefore, to determine the effect of endurance training on O2 saturation of Mb (SmbO2) and PmbO2 kinetics during muscle contraction. Male Wistar rats were subjected to a 4-week swimming training (Tr group; 6 days per week, 30 min × 4 sets per day) with a weight load of 2% body mass. After the training period, deoxygenated Mb kinetics during muscle contraction were measured using near-infrared spectroscopy under hemoglobin-free medium perfusion. In the Tr group, the VmO2peak significantly increased by 32%. Although the PmbO2 during muscle contraction did not affect the increased mVO2 in endurance-trained muscle, the O2 release rate from Mb increased because of the increased Mb concentration and faster decremental rate in SmbO2 at the maximal twitch tension. These results suggest that the Mb dynamics during muscle contraction are contributing factors to faster VO2 kinetics in endurance-trained muscle.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. Contraction mode itself does not determine the level of mTORC1 activity in rat skeletal muscle.

    Science.gov (United States)

    Ato, Satoru; Makanae, Yuhei; Kido, Kohei; Fujita, Satoshi

    2016-10-01

    Resistance training with eccentric contraction has been shown to augment muscle hypertrophy more than other contraction modes do (i.e., concentric and isometric contraction). However, the molecular mechanisms involved remain unclear. The purpose of this study was to investigate the effect of muscle contraction mode on mammalian target of rapamycin complex 1 (mTORC1) signaling using a standardized force-time integral (load (weight) × contraction time). Male Sprague-Dawley rats were randomly assigned to three groups: eccentric contraction, concentric contraction, and isometric contraction. The right gastrocnemius muscle was exercised via percutaneous electrical stimulation-induced maximal contraction. In experiment 1, different modes of muscle contraction were exerted using the same number of reps in all groups, while in experiment 2, muscle contractions were exerted using a standardized force-time integral. Muscle samples were obtained immediately and 3 h after exercise. Phosphorylation of molecules associated with mTORC1 activity was assessed using western blot analysis. In experiment 1, the force-time integral was significantly different among contraction modes with a higher force-time integral for eccentric contraction compared to that for other contraction modes (P contraction compared to that for isometric contraction (P contraction than for other modes of contraction (P contraction was higher than isometric contraction (P contraction modes 3 h after exercise. Our results suggest that mTORC1 activity is not determined by differences in muscle contraction mode itself. Instead, mTORC1 activity is determined by differences in the force-time integral during muscle contraction. © 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

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

    Science.gov (United States)

    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

  19. Effects of contraction on localization of GLUT4 and v-SNARE isoforms in rat skeletal muscle

    DEFF Research Database (Denmark)

    Rose, Adam John; Jeppesen, Jacob; Kiens, Bente

    2009-01-01

    In skeletal muscle, contractions increase glucose uptake due to a translocation of GLUT4 glucose transporters from intracellular storage sites to the surface membrane. Vesicle associated membrane proteins (VAMPs) are believed to play an important role in docking and fusion of the GLUT4 transporters...... at the surface membrane. However, knowledge about which VAMP isoforms in fact co-localize with GLUT4 vesicles in mature skeletal muscle and whether they translocate during muscle contractions is incomplete. The aim of the present study was to further identify VAMP isoforms which are associated with GLUT4......, there was a redistribution of VAMP2 (+240 +/- 40%), VAMP5 (+79 +/- 9%) and VAMP7 (+79 +/- 29%), but not VAMP3, to fractions enriched in heavy membranes away from low density membranes (-49 +/- 10%, -54 +/- 9%, -14 +/- 11%, respectively) in contracted versus resting muscle. In summary, VAMP2, VAMP3, VAMP5 and VAMP7 co...

  20. 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...

  1. Rat whisker movement after facial nerve lesion: Evidence for autonomic contraction of skeletal muscle.

    NARCIS (Netherlands)

    Heaton, J.T.; Sheu, S.H.; Hohman, M.H.; Knox, C.J.; Weinberg, J.S.; Kleiss, I.J.; Hadlock, T.A.

    2014-01-01

    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

  2. Expression of collagen and related growth factors in rat tendon and skeletal muscle in response to specific contraction types.

    Science.gov (United States)

    Heinemeier, K M; Olesen, J L; Haddad, F; Langberg, H; Kjaer, M; Baldwin, K M; Schjerling, P

    2007-08-01

    Acute exercise induces collagen synthesis in both tendon and muscle, indicating an adaptive response in the connective tissue of the muscle-tendon unit. However, the mechanisms of this adaptation, potentially involving collagen-inducing growth factors (such as transforming growth factor-beta-1 (TGF-beta-1)), as well as enzymes related to collagen processing, are not clear. Furthermore, possible differential effects of specific contraction types on collagen regulation have not been investigated. Female Sprague-Dawley rats were subjected to 4 days of concentric, eccentric or isometric training (n = 7-9 per group) of the medial gastrocnemius, by stimulation of the sciatic nerve. RNA was extracted from medial gastrocnemius and Achilles tendon tissue 24 h after the last training bout, and mRNA levels for collagens I and III, TGF-beta-1, connective tissue growth factor (CTGF), lysyl oxidase (LOX), metalloproteinases (MMP-2 and -9) and their inhibitors (TIMP-1 and 2) were measured by Northern blotting and/or real-time PCR. In tendon, expression of TGF-beta-1 and collagens I and III (but not CTGF) increased in response to all types of training. Similarly, enzymes/factors involved in collagen processing were induced in tendon, especially LOX (up to 37-fold), which could indicate a loading-induced increase in cross-linking of tendon collagen. In skeletal muscle, a similar regulation of gene expression was observed, but in contrast to the tendon response, the effect of eccentric training was significantly greater than the effect of concentric training on the expression of several transcripts. In conclusion, the study supports an involvement of TGF-beta-1 in loading-induced collagen synthesis in the muscle-tendon unit and importantly, it indicates that muscle tissue is more sensitive than tendon to the specific mechanical stimulus.

  3. Glycolysis in contracting rat skeletal muscle is controlled by factors related to energy state

    DEFF Research Database (Denmark)

    Ørtenblad, Niels; Macdonald, Will A; Sahlin, Kent

    2009-01-01

    The control of glycolysis in contracting muscle is not fully understood. The aim of the present study was to examine whether activation of glycolysis is mediated by factors related to the energy state or by a direct effect of Ca2+ on the regulating enzymes. Extensor digitorum longus muscles from...... and 58% of those in Con respectively. Glycolytic rate in BTS was only 51% of that in Con but the relative contribution of ATP derived from PCr (phosphocreatine) and glycolysis and the relation between muscle contents of PCr and Lac (lactate) were not different. Prolonged cyanide incubation of quiescent...... contribution of energy delivered from PCr and glycolysis during both conditions suggests that the glycolytic rate is controlled by factors related to energy state....

  4. 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...

  5. High-intensity stretch-shortening contraction training modifies responsivity of skeletal muscle in old male rats.

    Science.gov (United States)

    Rader, Erik P; Naimo, Marshall A; Ensey, James; Baker, Brent A

    2018-04-01

    Utilization of high-intensity resistance training to counter age-related sarcopenia is currently debated because of the potential for maladaptation when training design is inappropriate. Training design is problematic because the influence of various loading variables (e.g. contraction mode, repetition number, and training frequency) is still not well characterized at old age. To address this in a precisely controlled manner, we developed a rodent model of high-intensity training consisting of maximally-activated stretch-shortening contractions (SSCs), contractions typical during resistance training. With this model, we determined that at old age, high-repetition SSC training (80 SSCs: 8 sets of 10 repetitions) performed frequently (i.e. 3 days per week) for 4.5 weeks induced strength deficits with no muscle mass gain while decreasing frequency to 2 days per week promoted increases in muscle mass and muscle quality (i.e. performance normalized to muscle mass). This finding confirmed the popular notion that decreasing training frequency has a robust effect with age. Meanwhile, the influence of other loading variables remains contentious. The aim of the present study was to assess muscle adaptation following modulation of contraction mode and repetition number during high-intensity SSC training. Muscles of young (3 month old) and old (30 month old) male rats were exposed to 4.5 weeks of low-repetition static training of 4 (i.e. 4 sets of one repetition) isometric (ISO) contractions 3 days per week or a more moderate-repetition dynamic training of 40 SSCs (i.e. 4 sets of 10 repetitions) 3 days per week. For young rats, performance and muscle mass increased regardless of training protocol. For old rats, no muscle mass adaptation was observed for 4 ISO training while 40 SSC training induced muscle mass gain without improvement in muscle quality, an outcome distinct from modulating training frequency. Muscle mass gain for old rats was accompanied by

  6. Altered Regulation of Contraction-Induced Akt/mTOR/p70S6k Pathway Signaling in Skeletal Muscle of the Obese Zucker Rat

    Directory of Open Access Journals (Sweden)

    Anjaiah Katta

    2009-01-01

    Full Text Available Increased muscle loading results in the phosphorylation of the 70 kDa ribosomal S6 kinase (p70S6k, and this event is strongly correlated with the degree of muscle adaptation following resistance exercise. Whether insulin resistance or the comorbidities associated with this disorder may affect the ability of skeletal muscle to activate p70S6k signaling following an exercise stimulus remains unclear. Here, we compare the contraction-induced activation of p70S6k signaling in the plantaris muscles of lean and insulin resistant obese Zucker rats following a single bout of increased contractile loading. Compared to lean animals, the basal phosphorylation of p70S6k (Thr389; 37.2% and Thr421/Ser424; 101.4%, Akt (Thr308; 25.1%, and mTOR (Ser2448; 63.0% was higher in obese animals. Contraction increased the phosphorylation of p70S6k (Thr389, Akt (Ser473, and mTOR (Ser2448 in both models however the magnitude and kinetics of activation differed between models. These results suggest that contraction-induced activation of p70S6k signaling is altered in the muscle of the insulin resistant obese Zucker rat.

  7. 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.

  8. Hydrogen peroxide increases depolarization-induced contraction of mechanically skinned slow twitch fibres from rat skeletal muscles.

    Science.gov (United States)

    Plant, David R; Lynch, Gordon S; Williams, David A

    2002-03-15

    The effect of exogenous hydrogen peroxide (H(2)O(2)) on excitation-contraction (E-C) coupling and sarcoplasmic reticulum (SR) function was compared in mechanically skinned slow twitch fibres (prepared from the soleus muscles) and fast twitch fibres (prepared from the extensor digitorum longus; EDL muscles) of adult rats. Equilibration (5 min) with 1 mM H(2)O(2) diminished the ability of the Ca(2+)-depleted SR to reload Ca(2+) in both slow (P fast twitch fibres (P fast twitch fibres by 24 +/- 5 % (P slow twitch fibres. Treatment with 1 mM H(2)O(2) also increased the peak force of low [caffeine] contracture by approximately 45% in both fibre types compared to control (P slow twitch fibres, compared to control (no H(2)O(2); P fast twitch fibres was not altered by 1 mM H(2)O(2) treatment. Equilibration with 5 mM H(2)O(2) induced a spontaneous force response in both slow and fast twitch fibres, which could be partly reversed by 2 min treatment with 10 mM DTT. Peak DICR was also increased approximately 40% by 5 mM H(2)O(2) in slow twitch fibres compared to control (no H(2)O(2); P slow but not fast twitch fibres. The increase in depolarization-induced contraction in slow twitch fibres might be mediated by an increased SR Ca(2+) release during contraction and/or an increase in Ca(2+) sensitivity.

  9. Expression of collagen and related growth factors in rat tendon and skeletal muscle in response to specific contraction types

    DEFF Research Database (Denmark)

    Heinemeier, K M; Olesen, J L; Haddad, F

    2007-01-01

    greater than the effect of concentric training on the expression of several transcripts. In conclusion, the study supports an involvement of TGF-beta-1 in loading-induced collagen synthesis in the muscle-tendon unit and importantly, it indicates that muscle tissue is more sensitive than tendon......Acute exercise induces collagen synthesis in both tendon and muscle, indicating an adaptive response in the connective tissue of the muscle-tendon unit. However, the mechanisms of this adaptation, potentially involving collagen-inducing growth factors (such as transforming growth factor-beta-1 (TGF......-beta-1)), as well as enzymes related to collagen processing, are not clear. Furthermore, possible differential effects of specific contraction types on collagen regulation have not been investigated. Female Sprague-Dawley rats were subjected to 4 days of concentric, eccentric or isometric training (n = 7...

  10. Role of calpain in eccentric contraction-induced proteolysis of Ca2+-regulatory proteins and force depression in rat fast-twitch skeletal muscle.

    Science.gov (United States)

    Kanzaki, Keita; Watanabe, Daiki; Kuratani, Mai; Yamada, Takashi; Matsunaga, Satoshi; Wada, Masanobu

    2017-02-01

    The aim of this study was to examine the in vivo effects of eccentric contraction (ECC) on calpain-dependent proteolysis of Ca 2+ -regulatory proteins and force production in fast-twitch skeletal muscles. Rat extensor digitorum longus muscles were exposed to 200 repeated ECC in situ and excised immediately [recovery 0 (REC0)] or 3 days [recovery 3 (REC3)] after cessation of ECC. Calpain inhibitor (CI)-treated rats were intraperitoneally injected with MDL-28170 before ECC and during REC3. Tetanic force was markedly reduced at REC0 and remained reduced at REC3. CI treatment ameliorated the ECC-induced force decline but only at REC3. No evidence was found for proteolysis of dihydropyridine receptor (DHPR), junctophilin (JP)1, JP2, ryanodine receptor (RyR), sarcoplasmic reticulum Ca 2+ -ATPase (SERCA)1a, or junctional face protein-45 at REC0. At REC3, ECC resulted in decreases in DHPR, JP1, JP2, RyR, and SERCA1a. CI treatment prevented the decreases in DHPR, JP1, and JP2, whereas it had little effect on RyR and SERCA1a. These findings suggest that DHPR, JP1, and JP2, but not RyR and SERCA1a, undergo calpain-dependent proteolysis in in vivo muscles subjected to ECC and that impaired function of DHPR and/or JP might cause prolonged force deficits with ECC. NEW & NOTEWORTHY Calpain-dependent proteolysis is one of the contributing factors to muscle damage that occurs with eccentric contraction (ECC). It is unclear, however, whether calpains account for proteolysis of Ca 2+ -regulatory proteins in in vivo muscles subjected to ECC. Here, we provide evidence that dihydropyridine receptor and junctophilin, but not ryanodine receptor and sarcoplasmic reticulum Ca 2+ -ATPase, undergo calpain-dependent proteolysis. Copyright © 2017 the American Physiological Society.

  11. 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.

  12. Na+-K+ pump location and translocation during muscle contraction  in rat skeletal muscle

    DEFF Research Database (Denmark)

    Kristensen, Michael; Rasmussen, Martin Krøyer; Juel, Carsten

    2008-01-01

    the translocation. Electrical stimulation and biotin labeling of rat muscle revealed a 40% and 18% increase in the amounts of the Na+-K+ pump a2 subunit and caveolin-3 (Cav-3), respectively, in the sarcolemma. Exercise induced a 36% and 19% increase in the relative amounts of the a2 subunit and Cav-3, respectively...

  13. Glucose uptake and transport in contracting, perfused rat muscle with different pre-contraction glycogen concentrations

    DEFF Research Database (Denmark)

    Hespel, P; Richter, Erik

    1990-01-01

    1. Glucose uptake and transport, muscle glycogen, free glucose and glucose-6-phosphate concentrations were studied in perfused resting and contracting rat skeletal muscle with different pre-contraction glycogen concentrations. Rats were pre-conditioned by a combination of swimming exercise and diet......, resulting in either low (glycogen-depleted rats), normal (control rats) or high (supercompensated rats) muscle glycogen concentrations at the time their hindlimbs were perfused. 2. Compared with control rats, pre-contraction muscle glycogen concentration was approximately 40% lower in glycogen-depleted rats......, whereas it was 40% higher in supercompensated rats. Muscle glycogen break-down correlated positively (r = 0.76; P less than 0.001) with pre-contraction muscle glycogen concentration. 3. Glucose uptake during contractions was approximately 50% higher in glycogen-depleted hindquarters than in control...

  14. Muscle plasticity related to changes in tubulin and αB-crystallin levels induced by eccentric contraction in rat skeletal muscles.

    Science.gov (United States)

    Jee, H; Ochi, E; Sakurai, T; Lim, J-Y; Nakazato, K; Hatta, H

    2016-09-01

    We used the model of eccentric contraction of the hindlimb muscle by Ochi et al. to examine the role of eccentric contraction in muscle plasticity. This model aims to focus on stimulated skeletal muscle responses by measuring tissue weights and tracing the quantities of αB-crystallin and tubulin. The medial gastrocnemius muscle (GCM) responded to electrically induced eccentric contraction (EIEC) with significant increases in tissue weight (p muscle weight after EIEC. EIEC in the GCM caused contractile-induced sustenance of the traced proteins, but the soleus muscle exhibited a remarkable decrease in α-tubulin and a 19% decrease in αB-crystallin. EIEC caused fast-to-slow myosin heavy chain (MHC) isoform type-oriented shift within both the GCM and soleus muscle. These results have shown that different MHC isoform type-expressing slow and fast muscles commonly undergo fast-to-slow type MHC isoform transformation. This suggests that different levels of EIEC affected each of the slow and fast muscles to induce different quantitative changes in the expression of αB-crystallin and α-tubulin.

  15. 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...

  16. 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.

  17. 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

  18. 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.

  19. Dynamic imaging of skeletal muscle contraction in three orthogonal directions

    NARCIS (Netherlands)

    Lopata, R.G.; van Dijk, J.P; Pillen, S.; Nillisen, M.M.; Maas, H.; Thijssen, J.M.; Stegeman, D.F.; Korte, C.L.

    2010-01-01

    In this study, a multidimensional strain estimation method using biplane ultrasound is presented to assess local relative deformation (i.e., local strain) in three orthogonal directions in skeletal muscles during induced and voluntary contractions. The method was tested in the musculus biceps

  20. Dynamic imaging of skeletal muscle contraction in three orthogonal directions.

    NARCIS (Netherlands)

    Lopata, R.G.P.; Dijk, J.P. van; Pillen, S.; Nillesen, M.M.; Maas, H.; Thijssen, J.M.; Stegeman, D.F.; Korte, C.L. de

    2010-01-01

    In this study, a multidimensional strain estimation method using biplane ultrasound is presented to assess local relative deformation (i.e., local strain) in three orthogonal directions in skeletal muscles during induced and voluntary contractions. The method was tested in the musculus biceps

  1. Energetic aspects of skeletal muscle contraction: implications of fiber types.

    Science.gov (United States)

    Rall, J A

    1985-01-01

    In this chapter fundamental energetic properties of skeletal muscles as elucidated from isolated muscle preparations are described. Implications of these intrinsic properties for the energetic characterization of different fiber types and for the understanding of locomotion have been considered. Emphasis was placed on the myriad of physical and chemical techniques that can be employed to understand muscle energetics and on the interrelationship of results from different techniques. The anaerobic initial processes which liberate energy during contraction and relaxation are discussed in detail. The high-energy phosphate (approximately P) utilized during contraction and relaxation can be distributed between actomyosin ATPase or cross-bridge cycling (70%) and the Ca2+ ATPase of the sacroplasmic reticulum (30%). Muscle shortening increases the rate of approximately P hydrolysis, and stretching a muscle during contraction suppresses the rate of approximately P hydrolysis. The economy of an isometric contraction is defined as the ratio of isometric mechanical response to energetic cost and is shown to be a fundamental intrinsic parameter describing muscle energetics. Economy of contraction varies across the animal kingdom by over three orders of magnitude and is different in different mammalian fiber types. In mammalian skeletal muscles differences in economy of contraction can be attributed mainly to differences in the specific actomyosin and Ca2+ ATPase of muscles. Furthermore, there is an inverse relationship between economy of contraction and maximum velocity of muscle shortening (Vmax) and maximum power output. This is a fundamental relationship. Muscles cannot be economical at developing and maintaining force and also exhibit rapid shortening. Interestingly, there appears to be a subtle system of unknown nature that modulates the Vmax and economy of contraction. Efficiency of a work-producing contraction is defined and contrasted to the economy of contraction

  2. 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...

  3. Improved Cell Culture Method for Growing Contracting Skeletal Muscle Models

    Science.gov (United States)

    Marquette, Michele L.; Sognier, Marguerite A.

    2013-01-01

    An improved method for culturing immature muscle cells (myoblasts) into a mature skeletal muscle overcomes some of the notable limitations of prior culture methods. The development of the method is a major advance in tissue engineering in that, for the first time, a cell-based model spontaneously fuses and differentiates into masses of highly aligned, contracting myotubes. This method enables (1) the construction of improved two-dimensional (monolayer) skeletal muscle test beds; (2) development of contracting three-dimensional tissue models; and (3) improved transplantable tissues for biomedical and regenerative medicine applications. With adaptation, this method also offers potential application for production of other tissue types (i.e., bone and cardiac) from corresponding precursor cells.

  4. 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.

  5. The contraction induced increase in gene expression of peroxisome proliferator-activated receptor (PPAR)-gamma coactivator 1alpha (PGC-1alpha), mitochondrial uncoupling protein 3 (UCP3) and hexokinase II (HKII) in primary rat skeletal muscle cells is dependent on reactive oxygen species

    DEFF Research Database (Denmark)

    Silveira, Leonardo R.; Pilegaard, Henriette; Kusuhara, Keiko

    2006-01-01

    We evaluated the role of reactive oxygen species (ROS) for the contraction induced increase in expression of PGC-1alpha, HKII and UCP3 mRNA. Rat skeletal muscle cells were subjected to acute or repeated electrostimulation in the presence and absence of antioxidants. Contraction of muscle cells lead...... to an increased H2O2 formation, as measured by oxidation of H2HFF. Acute contraction of the muscle cells lead to a transient increase in PGC-1alpha and UCP3 mRNA by 172 and 65%, respectively (pantioxidants. Repeated contraction sessions induced...... a sustained elevation in PGC-1alpha and UCP3 mRNA and a transient increase in HKII (pantioxidant cocktail or with GPX+GSH. Incubation of cells for 10 days with ROS produced by xanthine oxidase/xanthine increased the level of PGC-1...

  6. Reduced blood flow to contracting skeletal muscle in ageing humans

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin; Hellsten, Ylva

    2016-01-01

    The ability to sustain a given absolute submaximal workload declines with advancing age likely due to a lower level of blood flow and O2 delivery to the exercising muscles. Given that physical inactivity mimics many of the physiological changes associated with ageing, separating the physiological...... consequences of ageing and physical inactivity can be challenging; yet, observations from cross-sectional and longitudinal studies on the effects of physical activity have provided some insight. Physical activity has the potential to offset the age-related decline in blood flow to contracting skeletal muscle...... the O2 demand of the active skeletal muscle of aged individuals during conditions where systemic blood flow is not limited by cardiac output seems to a large extent to be related to the level of physical activity. This article is protected by copyright. All rights reserved....

  7. Downstream mechanisms of nitric oxide-mediated skeletal muscle glucose uptake during contraction.

    Science.gov (United States)

    Merry, Troy L; Lynch, Gordon S; McConell, Glenn K

    2010-12-01

    There is evidence that nitric oxide (NO) is required for the normal increases in skeletal muscle glucose uptake during contraction, but the mechanisms involved have not been elucidated. We examined whether NO regulates glucose uptake during skeletal muscle contractions via cGMP-dependent or cGMP-independent pathways. Isolated extensor digitorum longus (EDL) muscles from mice were stimulated to contract ex vivo, and potential NO signaling pathways were blocked by the addition of inhibitors to the incubation medium. Contraction increased (P contraction by ∼50% (P contraction; however, DTT attenuated (P contraction-stimulated glucose uptake (by 70%). NOS inhibition and antioxidant treatment reduced contraction-stimulated increases in protein S-glutathionylation and tyrosine nitration (P skeletal muscle glucose uptake during ex vivo contractions via a cGMP/PKG-, AMPK-, and p38 MAPK-independent pathway. In addition, it appears that NO and ROS may regulate skeletal muscle glucose uptake during contraction through a similar pathway.

  8. Skeletal muscle microvascular and interstitial PO2 from rest to contractions.

    Science.gov (United States)

    Hirai, Daniel M; Craig, Jesse C; Colburn, Trenton D; Eshima, Hiroaki; Kano, Yutaka; Sexton, William L; Musch, Timothy I; Poole, David C

    2018-03-01

    Oxygen pressure gradients across the microvascular walls are essential for oxygen diffusion from blood to tissue cells. At any given flux, the magnitude of these transmural gradients is proportional to the local resistance. The greatest resistance to oxygen transport into skeletal muscle is considered to reside in the short distance between red blood cells and myocytes. Although crucial to oxygen transport, little is known about transmural pressure gradients within skeletal muscle during contractions. We evaluated oxygen pressures within both the skeletal muscle microvascular and interstitial spaces to determine transmural gradients during the rest-contraction transient in anaesthetized rats. The significant transmural gradient observed at rest was sustained during submaximal muscle contractions. Our findings support that the blood-myocyte interface provides substantial resistance to oxygen diffusion at rest and during contractions and suggest that modulations in microvascular haemodynamics and red blood cell distribution constitute primary mechanisms driving increased transmural oxygen flux with contractions. Oxygen pressure (PO2) gradients across the blood-myocyte interface are required for diffusive O 2 transport, thereby supporting oxidative metabolism. The greatest resistance to O 2 flux into skeletal muscle is considered to reside between the erythrocyte surface and adjacent sarcolemma, although this has not been measured during contractions. We tested the hypothesis that O 2 gradients between skeletal muscle microvascular (PO2 mv ) and interstitial (PO2 is ) spaces would be present at rest and maintained or increased during contractions. PO2 mv and PO2 is   were determined via phosphorescence quenching (Oxyphor probes G2 and G4, respectively) in the exposed rat spinotrapezius during the rest-contraction transient (1 Hz, 6 V; n = 8). PO2 mv was higher than PO2 is in all instances from rest (34.9 ± 6.0 versus 15.7 ± 6.4) to contractions (28.4 ± 5

  9. Tomographic elastography of contracting skeletal muscles from their natural vibrations

    Science.gov (United States)

    Sabra, Karim G.; Archer, Akibi

    2009-11-01

    Conventional elastography techniques require an external mechanical or radiation excitation to measure noninvasively the viscoelastic properties of skeletal muscles and thus monitor human motor functions. We developed instead a passive elastography technique using only an array of skin-mounted accelerometers to record the low-frequency vibrations of the biceps brachii muscle naturally generated during voluntary contractions and to determine their two-dimensional directionality. Cross-correlating these recordings provided travel-times measurements of these muscle vibrations between multiple sensor pairs. Travel-time tomographic inversions yielded spatial variations of their propagation velocity during isometric elbow flexions which indicated a nonuniform longitudinal stiffening of the biceps.

  10. Skeletal muscle PLIN proteins, ATGL and CGI-58, interactions at rest and following stimulated contraction

    Science.gov (United States)

    Ramos, Sofhia V.; Vandenboom, Rene; Roy, Brian D.; Peters, Sandra J.

    2013-01-01

    Evidence indicates that skeletal muscle lipid droplet-associated proteins (PLINs) regulate lipolysis through protein-protein interactions on the lipid droplet surface. In adipocytes, PLIN1 is thought to regulate lipolysis by directly interacting with comparative gene identification-58 (CGI-58), an activator of adipose triglyceride lipase (ATGL). Upon lipolytic stimulation, PLIN1 is phosphorylated, releasing CGI-58 to fully activate ATGL and initiate triglyceride breakdown. The absence of PLIN1 in skeletal muscle leads us to believe that other PLIN family members undertake this role. Our purpose was to examine interactions between PLIN2, PLIN3, and PLIN5, with ATGL and its coactivator CGI-58 at rest and following contraction. Isolated rat solei were incubated for 30 min at rest or during 30 min of intermittent tetanic stimulation [150-ms volleys at 60 Hz with a train rate of 20 tetani/min (25°C)] to maximally stimulate intramuscular lipid breakdown. Results show that the interaction between ATGL and CGI-58 increased 128% following contraction (P = 0.041). Further, ATGL interacts with PLIN2, PLIN3, and PLIN5 at rest and following contraction. The PLIN2-ATGL interaction decreased significantly by 21% following stimulation (P = 0.013). Both PLIN3 and PLIN5 coprecipitated with CGI-58 at rest and following contraction, while there was no detectable interaction between PLIN2 and CGI-58 in either condition. Therefore, our findings indicate that in skeletal muscle, during contraction-induced muscle lipolysis, ATGL and CGI-58 strongly associate and that the PLIN proteins work together to regulate lipolysis, in part, by preventing ATGL and CGI-58 interactions at rest. PMID:23408028

  11. Skeletal muscle PLIN proteins, ATGL and CGI-58, interactions at rest and following stimulated contraction.

    Science.gov (United States)

    MacPherson, Rebecca E K; Ramos, Sofhia V; Vandenboom, Rene; Roy, Brian D; Peters, Sandra J

    2013-04-15

    Evidence indicates that skeletal muscle lipid droplet-associated proteins (PLINs) regulate lipolysis through protein-protein interactions on the lipid droplet surface. In adipocytes, PLIN1 is thought to regulate lipolysis by directly interacting with comparative gene identification-58 (CGI-58), an activator of adipose triglyceride lipase (ATGL). Upon lipolytic stimulation, PLIN1 is phosphorylated, releasing CGI-58 to fully activate ATGL and initiate triglyceride breakdown. The absence of PLIN1 in skeletal muscle leads us to believe that other PLIN family members undertake this role. Our purpose was to examine interactions between PLIN2, PLIN3, and PLIN5, with ATGL and its coactivator CGI-58 at rest and following contraction. Isolated rat solei were incubated for 30 min at rest or during 30 min of intermittent tetanic stimulation [150-ms volleys at 60 Hz with a train rate of 20 tetani/min (25°C)] to maximally stimulate intramuscular lipid breakdown. Results show that the interaction between ATGL and CGI-58 increased 128% following contraction (P = 0.041). Further, ATGL interacts with PLIN2, PLIN3, and PLIN5 at rest and following contraction. The PLIN2-ATGL interaction decreased significantly by 21% following stimulation (P = 0.013). Both PLIN3 and PLIN5 coprecipitated with CGI-58 at rest and following contraction, while there was no detectable interaction between PLIN2 and CGI-58 in either condition. Therefore, our findings indicate that in skeletal muscle, during contraction-induced muscle lipolysis, ATGL and CGI-58 strongly associate and that the PLIN proteins work together to regulate lipolysis, in part, by preventing ATGL and CGI-58 interactions at rest.

  12. Low Po2 conditions induce reactive oxygen species formation during contractions in single skeletal muscle fibers

    OpenAIRE

    Zuo, Li; Shiah, Amy; Roberts, William J.; Chien, Michael T.; Wagner, Peter D.; Hogan, Michael C.

    2013-01-01

    Contractions in whole skeletal muscle during hypoxia are known to generate reactive oxygen species (ROS); however, identification of real-time ROS formation within isolated single skeletal muscle fibers has been challenging. Consequently, there is no convincing evidence showing increased ROS production in intact contracting fibers under low Po2 conditions. Therefore, we hypothesized that intracellular ROS generation in single contracting skeletal myofibers increases during low Po2 compared wi...

  13. Nanosecond electric pulses modulate skeletal muscle calcium dynamics and contraction

    Science.gov (United States)

    Valdez, Chris; Jirjis, Michael B.; Roth, Caleb C.; Barnes, Ronald A.; Ibey, Bennett L.

    2017-02-01

    Irreversible electroporation therapy is utilized to remove cancerous tissues thru the delivery of rapid (250Hz) and high voltage (V) (1,500V/cm) electric pulses across microsecond durations. Clinical research demonstrated that bipolar (BP) high voltage microsecond pulses opposed to monophasic waveforms relieve muscle contraction during electroporation treatment. Our group along with others discovered that nanosecond electric pulses (nsEP) can activate second messenger cascades, induce cytoskeletal rearrangement, and depending on the nsEP duration and frequency, initiate apoptotic pathways. Of high interest across in vivo and in vitro applications, is how nsEP affects muscle physiology, and if nuances exist in comparison to longer duration electroporation applications. To this end, we exposed mature skeletal muscle cells to monopolar (MP) and BP nsEP stimulation across a wide range of electric field amplitudes (1-20 kV/cm). From live confocal microscopy, we simultaneously monitored intracellular calcium dynamics along with nsEP-induced muscle movement on a single cell level. In addition, we also evaluated membrane permeability with Yo-PRO-1 and Propidium Iodide (PI) across various nsEP parameters. The results from our findings suggest that skeletal muscle calcium dynamics, and nsEP-induced contraction exhibit exclusive responses to both MP and BP nsEP exposure. Overall the results suggest in vivo nsEP application may elicit unique physiology and field applications compared to longer pulse duration electroporation.

  14. 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

  15. The interrelation between aPKC and glucose uptake in the skeletal muscle during contraction and insulin stimulation.

    Science.gov (United States)

    Santos, J M; Benite-Ribeiro, S A; Queiroz, G; Duarte, J A

    2014-12-01

    Contraction and insulin increase glucose uptake in skeletal muscle. While the insulin pathway, better characterized, requires activation of phosphoinositide 3-kinase (PI3K) and atypical protein kinase (aPKC), muscle contraction seems to share insulin-activated components to increase glucose uptake. This study aimed to investigate the interrelation between the pathway involved in glucose uptake evoked by insulin and muscle contraction. Isolated muscle of rats was treated with solvent (control), insulin, wortmannin (PI3K inhibitor) and the combination of insulin plus wortmannin. After treatment, muscles were electrically stimulated (contracted) or remained at rest. Glucose transporter 4 (GLUT4) localization, glucose uptake and phospho-aPKC (aPKC activated form) were assessed. Muscle contraction and insulin increased glucose uptake in all conditions when compared with controls not stimulating an effect that was accompanied by an increase in GLUT4 and of phospho-aPKC at the muscle membrane. Contracted muscles treated with insulin did not show additive effects on glucose uptake or aPKC activity compared with the response when these stimuli were applied alone. Inhibition of PI3K blocked insulin effect on glucose uptake and aPKC but not in the contractile response. Thus, muscle contraction seems to stimulate aPKC and glucose uptake independently of PI3K. Therefore, aPKC may be a convergence point and a rate limit step in the pathway by which, insulin and contraction, increase glucose uptake in skeletal muscle. Copyright © 2014 John Wiley & Sons, Ltd.

  16. 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

  17. 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...

  18. Charge movement and depolarization-contraction coupling in arthropod vs. vertebrate skeletal muscle.

    OpenAIRE

    Scheuer, T; Gilly, W F

    1986-01-01

    Voltage-dependent charge movement has been characterized in arthropod skeletal muscle. Charge movement in scorpion (Centuroides sculpturatus) muscle is distinguishable from that in vertebrate skeletal muscle by criteria of kinetics, voltage dependence, and pharmacology. The function of scorpion charge movement is gating of calcium channels in the sarcolemma, and depolarization-contraction coupling relies on calcium influx through these channels.

  19. Brain-derived neurotrophic factor is produced by skeletal muscle cells in response to contraction and enhances fat oxidation via activation of AMP-activated protein kinase

    DEFF Research Database (Denmark)

    Matthews, V B; Åström, Maj-Brit; Chan, M H S

    2009-01-01

    C12 skeletal muscle cells were electrically stimulated to mimic contraction. L6 myotubes and isolated rat extensor digitorum longus muscles were treated with BDNF and phosphorylation of the proteins AMP-activated protein kinase (AMPK) (Thr(172)) and acetyl coenzyme A carboxylase beta (ACCbeta) (Ser...... kinase (p44/42 Thr(202)/Tyr(204)) phosphorylation in these muscles. In addition, phosphorylation of ACCbeta was markedly elevated in the Bdnf electroporated muscles. CONCLUSIONS/INTERPRETATION: These data identify BDNF as a contraction-inducible protein in skeletal muscle that is capable of enhancing...

  20. Phosphatidylinositol 3-phosphate 5-kinase (PIKfyve) is an AMPK target participating in contraction-stimulated glucose uptake in skeletal muscle.

    Science.gov (United States)

    Liu, Yang; Lai, Yu-Chiang; Hill, Elaine V; Tyteca, Donatienne; Carpentier, Sarah; Ingvaldsen, Ada; Vertommen, Didier; Lantier, Louise; Foretz, Marc; Dequiedt, Franck; Courtoy, Pierre J; Erneux, Christophe; Viollet, Benoît; Shepherd, Peter R; Tavaré, Jeremy M; Jensen, Jørgen; Rider, Mark H

    2013-10-15

    PIKfyve (FYVE domain-containing phosphatidylinositol 3-phosphate 5-kinase), the lipid kinase that phosphorylates PtdIns3P to PtdIns(3,5)P2, has been implicated in insulin-stimulated glucose uptake. We investigated whether PIKfyve could also be involved in contraction/AMPK (AMP-activated protein kinase)-stimulated glucose uptake in skeletal muscle. Incubation of rat epitrochlearis muscles with YM201636, a selective PIKfyve inhibitor, reduced contraction- and AICAriboside (5-amino-4-imidazolecarboxamide riboside)-stimulated glucose uptake. Consistently, PIKfyve knockdown in C2C12 myotubes reduced AICAriboside-stimulated glucose transport. Furthermore, muscle contraction increased PtdIns(3,5)P2 levels and PIKfyve phosphorylation. AMPK phosphorylated PIKfyve at Ser307 both in vitro and in intact cells. Following subcellular fractionation, PIKfyve recovery in a crude intracellular membrane fraction was increased in contracting versus resting muscles. Also in opossum kidney cells, wild-type, but not S307A mutant, PIKfyve was recruited to endosomal vesicles in response to AMPK activation. We propose that PIKfyve activity is required for the stimulation of skeletal muscle glucose uptake by contraction/AMPK activation. PIKfyve is a new AMPK substrate whose phosphorylation at Ser307 could promote PIKfyve translocation to endosomes for PtdIns(3,5)P2 synthesis to facilitate GLUT4 (glucose transporter 4) translocation.

  1. Contraction-induced skeletal muscle FAT/CD36 trafficking and FA uptake is AMPK independent

    DEFF Research Database (Denmark)

    Jeppesen, Jacob; Albers, Peter Hjorth; Rose, Adam John

    2011-01-01

    The aim of this study was to investigate the molecular mechanisms regulating FAT/CD36 translocation and fatty acid uptake in skeletal muscle during contractions. In one model, WT and AMPK KD mice were exercised or EDL and SOL muscles were contracted, ex vivo. In separate studies, FAT/CD36 translo...

  2. Rac1 is a novel regulator of contraction-stimulated glucose uptake in skeletal muscle

    DEFF Research Database (Denmark)

    Sylow, Lykke; Jensen, Thomas Elbenhardt; Kleinert, Maximilian

    2013-01-01

    In skeletal muscle, the actin cytoskeleton-regulating GTPase, Rac1, is necessary for insulin-dependent GLUT4 translocation. Muscle contraction increases glucose transport and represents an alternative signaling pathway to insulin. Whether Rac1 is activated by muscle contraction and regulates...

  3. Effects of contraction mode and stimulation frequency on electrical stimulation-induced skeletal muscle hypertrophy.

    Science.gov (United States)

    Ashida, Yuki; Himori, Koichi; Tatebayashi, Daisuke; Yamada, Ryotaro; Ogasawara, Riki; Yamada, Takashi

    2018-02-01

    We compared the skeletal muscle hypertrophy resulting from isometric (Iso) or eccentric (Ecc) electrical stimulation (ES) training with different stimulation frequencies. Male Wistar rats were assigned to the Iso and Ecc groups. These were divided into three further subgroups that were stimulated at 10 Hz (Iso-10 and Ecc-10), 30 Hz (Iso-30 and Ecc-30), or 100 Hz (Iso-100 and Ecc-100). In experiment 1, the left plantarflexor muscles were stimulated every other day for 3 wk. In experiment 2, mammalian target of rapamycin complex 1 (mTORC1) signaling was investigated 6 h after one bout of ES. The contralateral right muscle served as a control (non-ES). Ecc contractions comprised forced dorsiflexion combined with ES. The peak torque and torque-time integral during ES were higher in the Ecc group than that in the Iso group in all stimulation frequencies examined. The gastrocnemius muscle weight normalized to body weight in ES side was increased compared with the non-ES side by 6, 7, and 17% in the Ecc-30, Iso-100, and Ecc-100 groups, respectively, with a greater gain in Ecc-100 than the Ecc-30 and Iso-100 groups. The p70S6K (Thr389) phosphorylation level was higher in the Ecc-30 and -100 than in the Iso-30 and -100 groups, respectively. The peak torque and torque-time integral were highly correlated with the magnitude of increase in muscle mass and the phosphorylation of p70S6K. These data suggest that ES-induced muscle hypertrophy and mTORC1 activity are determined by loading intensity and volume during muscle contraction independent of the contraction mode. NEW & NOTEWORTHY Eccentric contraction and high-frequency stimulation (HFS) are regarded as an effective way to increase muscle mass by electrical stimulation (ES) training. However, little is known about whether muscle hypertrophy is affected by contraction mode and stimulation frequency in ES training. Here, we provide the evidence that muscle hypertrophy and mammalian target of rapamycin complex 1 activity are

  4. 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)

  5. Nitric oxide is required for the insulin sensitizing effects of contraction in mouse skeletal muscle.

    Science.gov (United States)

    Zhang, Xinmei; Hiam, Danielle; Hong, Yet-Hoi; Zulli, Anthony; Hayes, Alan; Rattigan, Stephen; McConell, Glenn K

    2017-12-15

    People with insulin resistance or type 2 diabetes can substantially increase their skeletal muscle glucose uptake during exercise and insulin sensitivity after exercise. Skeletal muscle nitric oxide (NO) is important for glucose uptake during exercise, although how prior exercise increases insulin sensitivity is unclear. In the present study, we examined whether NO is necessary for normal increases in skeletal muscle insulin sensitivity after contraction ex vivo in mouse muscle. The present study uncovers, for the first time, a novel role for NO in the insulin sensitizing effects of ex vivo contraction, which is independent of blood flow. The factors regulating the increase in skeletal muscle insulin sensitivity after exercise are unclear. We examined whether nitric oxide (NO) is required for the increase in insulin sensitivity after ex vivo contractions. Isolated C57BL/6J mouse EDL muscles were contracted for 10 min or remained at rest (basal) with or without the NO synthase (NOS) inhibition (N G -monomethyl-l-arginine; l-NMMA; 100 μm). Then, 3.5 h post contraction/basal, muscles were exposed to saline or insulin (120 μU ml -1 ) with or without l-NMMA during the last 30 min. l-NMMA had no effect on basal skeletal muscle glucose uptake. The increase in muscle glucose uptake with insulin (57%) was significantly (P contraction (140% increase). NOS inhibition during the contractions had no effect on this insulin-sensitizing effect of contraction, whereas NOS inhibition during insulin prevented the increase in skeletal muscle insulin sensitivity post-contraction. Soluble guanylate cyclase inhibition, protein kinase G (PKG) inhibition or cyclic nucleotide phosphodiesterase inhibition each had no effect on the insulin-sensitizing effect of prior contraction. In conclusion, NO is required for increases in insulin sensitivity several hours after contraction of mouse skeletal muscle via a cGMP/PKG independent pathway. © 2017 The Authors. The Journal of Physiology

  6. 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.

  7. Regulation of Blood Flow in Contracting Skeletal Muscle in Aging

    DEFF Research Database (Denmark)

    Piil, Peter Bergmann

    Oxygen delivery to skeletal muscle is regulated precisely to match the oxygen demand; however, with aging the regulation of oxygen delivery during exercise is impaired. The present thesis investigated mechanisms underlying the age-related impairment in regulation of blood flow and oxygen delivery......GMP) was used as intervention, and skeletal muscle blood flow, oxygen delivery, and functional sympatholysis was examined. The two studies included 53 healthy, habitually active, male subjects. All subjects participated in an experimental day in which femoral arterial blood flow and blood pressure were assessed...... that improving sympatholytic capacity by training may be a slower process in older than in young men. In conclusion, this thesis provides new important knowledge related to the regulation of skeletal muscle blood flow in aging. Specifically, it demonstrates that changes in cGMP signaling is an underlying cause...

  8. Glucose uptake during contraction in isolated skeletal muscles from neuronal nitric oxide synthase μ knockout mice.

    Science.gov (United States)

    Hong, Yet Hoi; Frugier, Tony; Zhang, Xinmei; Murphy, Robyn M; Lynch, Gordon S; Betik, Andrew C; Rattigan, Stephen; McConell, Glenn K

    2015-05-01

    Inhibition of nitric oxide synthase (NOS) significantly attenuates the increase in skeletal muscle glucose uptake during contraction/exercise, and a greater attenuation is observed in individuals with Type 2 diabetes compared with healthy individuals. Therefore, NO appears to play an important role in mediating muscle glucose uptake during contraction. In this study, we investigated the involvement of neuronal NOSμ (nNOSμ), the main NOS isoform activated during contraction, on skeletal muscle glucose uptake during ex vivo contraction. Extensor digitorum longus muscles were isolated from nNOSμ(-/-) and nNOSμ(+/+) mice. Muscles were contracted ex vivo in a temperature-controlled (30°C) organ bath with or without the presence of the NOS inhibitor N(G)-monomethyl-l-arginine (L-NMMA) and the NOS substrate L-arginine. Glucose uptake was determined by radioactive tracers. Skeletal muscle glucose uptake increased approximately fourfold during contraction in muscles from both nNOSμ(-/-) and nNOSμ(+/+) mice. L-NMMA significantly attenuated the increase in muscle glucose uptake during contraction in both genotypes. This attenuation was reversed by L-arginine, suggesting that L-NMMA attenuated the increase in muscle glucose uptake during contraction by inhibiting NOS and not via a nonspecific effect of the inhibitor. Low levels of NOS activity (~4%) were detected in muscles from nNOSμ(-/-) mice, and there was no evidence of compensation from other NOS isoform or AMP-activated protein kinase which is also involved in mediating muscle glucose uptake during contraction. These results indicate that NO regulates skeletal muscle glucose uptake during ex vivo contraction independently of nNOSμ. Copyright © 2015 the American Physiological Society.

  9. Calcium influx through L-type channels attenuates skeletal muscle contraction via inhibition of adenylyl cyclases.

    Science.gov (United States)

    Menezes-Rodrigues, Francisco Sandro; Pires-Oliveira, Marcelo; Duarte, Thiago; Paredes-Gamero, Edgar Julian; Chiavegatti, Tiago; Godinho, Rosely Oliveira

    2013-11-15

    Skeletal muscle contraction is triggered by acetylcholine induced release of Ca(2+) from sarcoplasmic reticulum. Although this signaling pathway is independent of extracellular Ca(2+), L-type voltage-gated calcium channel (Cav) blockers have inotropic effects on frog skeletal muscles which occur by an unknown mechanism. Taking into account that skeletal muscle fiber expresses Ca(+2)-sensitive adenylyl cyclase (AC) isoforms and that cAMP is able to increase skeletal muscle contraction force, we investigated the role of Ca(2+) influx on mouse skeletal muscle contraction and the putative crosstalk between extracellular Ca(2+) and intracellular cAMP signaling pathways. The effects of Cav blockers (verapamil and nifedipine) and extracellular Ca(2+) chelator EGTA were evaluated on isometric contractility of mouse diaphragm muscle under direct electrical stimulus (supramaximal voltage, 2 ms, 0.1 Hz). Production of cAMP was evaluated by radiometric assay while Ca(2+) transients were assessed by confocal microscopy using L6 cells loaded with fluo-4/AM. Ca(2+) channel blockers verapamil and nifedipine had positive inotropic effect, which was mimicked by removal of extracellular Ca(+2) with EGTA or Ca(2+)-free Tyrode. While phosphodiesterase inhibitor IBMX potentiates verapamil positive inotropic effect, it was abolished by AC inhibitors SQ22536 and NYK80. Finally, the inotropic effect of verapamil was associated with increased intracellular cAMP content and mobilization of intracellular Ca(2+), indicating that positive inotropic effects of Ca(2+) blockers depend on cAMP formation. Together, our results show that extracellular Ca(2+) modulates skeletal muscle contraction, through inhibition of Ca(2+)-sensitive AC. The cross-talk between extracellular calcium and cAMP-dependent signaling pathways appears to regulate the extent of skeletal muscle contraction responses. © 2013 Published by Elsevier B.V.

  10. Contraction-mediated glycogenolysis in mouse skeletal muscle lacking creatine kinase: the role of phosphorylase b activation.

    NARCIS (Netherlands)

    Katz, A.; Andersson, D.C.; Yu, J.; Norman, B.; Sandstrom, M.E.; Wieringa, B.; Westerblad, H.

    2003-01-01

    Skeletal muscle that is deficient in creatine kinase (CK-/-) exhibits accelerated glycogenolysis during contraction. Understanding this phenomenon could provide insight into the control of glycogenolysis during contraction. Therefore, glycogen breakdown was investigated in isolated extensor

  11. 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...

  12. AICAR stimulation metabolome widely mimics electrical contraction in isolated rat epitrochlearis muscle.

    Science.gov (United States)

    Miyamoto, Licht; Egawa, Tatsuro; Oshima, Rieko; Kurogi, Eriko; Tomida, Yosuke; Tsuchiya, Koichiro; Hayashi, Tatsuya

    2013-12-15

    Physical exercise has potent therapeutic and preventive effects against metabolic disorders. A number of studies have suggested that 5'-AMP-activated protein kinase (AMPK) plays a pivotal role in regulating carbohydrate and lipid metabolism in contracting skeletal muscles, while several genetically manipulated animal models revealed the significance of AMPK-independent pathways. To elucidate significance of AMPK and AMPK-independent signals in contracting skeletal muscles, we conducted a metabolomic analysis that compared the metabolic effects of 5-aminoimidazole-4-carboxamide-1-β-D-ribonucleoside (AICAR) stimulation with the electrical contraction ex vivo in isolated rat epitrochlearis muscles, in which both α1- and α2-isoforms of AMPK and glucose uptake were equally activated. The metabolomic analysis using capillary electrophoresis time-of-flight mass spectrometry detected 184 peaks and successfully annotated 132 small molecules. AICAR stimulation exhibited high similarity to the electrical contraction in overall metabolites. Principal component analysis (PCA) demonstrated that the major principal component characterized common effects whereas the minor principal component distinguished the difference. PCA and a factor analysis suggested a substantial change in redox status as a result of AMPK activation. We also found a decrease in reduced glutathione levels in both AICAR-stimulated and contracting muscles. The muscle contraction-evoked influences related to the metabolism of amino acids, in particular, aspartate, alanine, or lysine, are supposed to be independent of AMPK activation. Our results substantiate the significance of AMPK activation in contracting skeletal muscles and provide novel evidence that AICAR stimulation closely mimics the metabolomic changes in the contracting skeletal muscles.

  13. Sepsis attenuates the anabolic response to skeletal muscle contraction.

    Science.gov (United States)

    Steiner, Jennifer L; Lang, Charles H

    2015-04-01

    Electrically stimulated muscle contraction is a potential clinical therapy to treat sepsis-induced myopathy; however, whether sepsis alters contraction-induced anabolic signaling is unknown. Polymicrobial peritonitis was produced by cecal ligation and puncture (CLP) in male C57BL/6 mice and time-matched, pair-fed controls (CON). At ∼24 h post-CLP, the right hindlimb was electrically stimulated via the sciatic nerve to evoke maximal muscle contractions, and the gastrocnemius was collected 2 h later. Protein synthesis was increased by muscle contraction in CON mice. Sepsis suppressed the rate of synthesis in both the nonstimulated (31%) and stimulated (57%) muscle versus CON. Contraction of muscle in CON mice increased the phosphorylation of mTORC1 (mammalian target of rapamycin [mTOR] complex 1) substrates S6K1 (70-kd ribosomal protein S6 kinase 1) Thr (8-fold), S6K1 ThrSer (7-fold) and 4E-BP1 Ser (11-fold). Sepsis blunted the contraction-induced phosphorylation of S6K1 Thr (67%), S6K1 ThrSer (46%), and 4E-BP1 Ser (85%). Conversely, sepsis did not appear to modulate protein elongation as eEF2 Thr phosphorylation was decreased similarly by muscle contraction in both groups. Mitogen-activated protein kinase signaling was discordant following contraction in septic muscle; phosphorylation of extracellular signal-regulated kinase ThrTyr and p38 ThrTyr was increased similarly in both CON and CLP mice, while sepsis prevented the contraction-induced phosphorylation of JNK ThrTyr and c-JUN Ser. The expression of interleukin 6 and tumor necrosis factor α (TNF-α) mRNA in muscle was increased by sepsis, and contraction increased TNF-α to a greater extent in muscle from septic than CON mice. Injection of the mTOR inhibitor Torin2 in separate mice confirmed that contraction-induced increases in S6K1 and 4E-BP1 were mTOR mediated. These findings demonstrate that resistance to contraction-induced anabolic signaling occurs during sepsis and is predominantly mTORC1-dependent.

  14. 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.

  15. β-Adrenergic modulation of skeletal muscle contraction: key role of excitation-contraction coupling.

    Science.gov (United States)

    Cairns, Simeon P; Borrani, Fabio

    2015-11-01

    Our aim is to describe the acute effects of catecholamines/β-adrenergic agonists on contraction of non-fatigued skeletal muscle in animals and humans, and explain the mechanisms involved. Adrenaline/β-agonists (0.1-30 μm) generally augment peak force across animal species (positive inotropic effect) and abbreviate relaxation of slow-twitch muscles (positive lusitropic effect). A peak force reduction also occurs in slow-twitch muscles in some conditions. β2 -Adrenoceptor stimulation activates distinct cyclic AMP-dependent protein kinases to phosphorylate multiple target proteins. β-Agonists modulate sarcolemmal processes (increased resting membrane potential and action potential amplitude) via enhanced Na(+) -K(+) pump and Na(+) -K(+) -2Cl(-) cotransporter function, but this does not increase force. Myofibrillar Ca(2+) sensitivity and maximum Ca(2+) -activated force are unchanged. All force potentiation involves amplified myoplasmic Ca(2+) transients consequent to increased Ca(2+) release from sarcoplasmic reticulum (SR). This unequivocally requires phosphorylation of SR Ca(2+) release channels/ryanodine receptors (RyR1) which sensitize the Ca(2+) -induced Ca(2+) release mechanism. Enhanced trans-sarcolemmal Ca(2+) influx through phosphorylated voltage-activated Ca(2+) channels contributes to force potentiation in diaphragm and amphibian muscle, but not mammalian limb muscle. Phosphorylation of phospholamban increases SR Ca(2+) pump activity in slow-twitch fibres but does not augment force; this process accelerates relaxation and may depress force. Greater Ca(2+) loading of SR may assist force potentiation in fast-twitch muscle. Some human studies show no significant force potentiation which appears to be related to the β-agonist concentration used. Indeed high-dose β-agonists (∼0.1 μm) enhance SR Ca(2+) -release rates, maximum voluntary contraction strength and peak Wingate power in trained humans. The combined findings can explain how adrenaline

  16. 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

  17. Rac1- a novel regulator of contraction-stimulated glucose uptake in skeletal muscle

    DEFF Research Database (Denmark)

    Sylow, Lykke; Møller, Lisbeth L V; Kleinert, Maximilian

    2014-01-01

    -stimulated glucose uptake in skeletal muscle, since muscle-specific Rac1 knockout mice display reduced ex vivo contraction- and in vivo exercise-stimulated glucose uptake in skeletal muscle. The molecular mechanisms by which Rac1 regulate glucose uptake is presently unknown. However, recent studies link Rac1......Muscle contraction stimulates muscle glucose uptake by facilitating translocation of the glucose transporter 4 from intracellular locations to the cell surface, which allows for diffusion of glucose into the myofibers. However, the intracellular mechanisms regulating this process are not well...... understood. The GTPase, Rac1 has, until recently, only been investigated with regards to its involvement in insulin-stimulated glucose uptake. However, we recently found that Rac1 is activated during muscle contraction and exercise in mice and humans. Remarkably, Rac1 seems to be necessary for exercise/contraction...

  18. Rac1 is a novel regulator of contraction-stimulated glucose uptake in skeletal muscle.

    Science.gov (United States)

    Sylow, Lykke; Jensen, Thomas E; Kleinert, Maximilian; Mouatt, Joshua R; Maarbjerg, Stine J; Jeppesen, Jacob; Prats, Clara; Chiu, Tim T; Boguslavsky, Shlomit; Klip, Amira; Schjerling, Peter; Richter, Erik A

    2013-04-01

    In skeletal muscle, the actin cytoskeleton-regulating GTPase, Rac1, is necessary for insulin-dependent GLUT4 translocation. Muscle contraction increases glucose transport and represents an alternative signaling pathway to insulin. Whether Rac1 is activated by muscle contraction and regulates contraction-induced glucose uptake is unknown. Therefore, we studied the effects of in vivo exercise and ex vivo muscle contractions on Rac1 signaling and its regulatory role in glucose uptake in mice and humans. Muscle Rac1-GTP binding was increased after exercise in mice (~60-100%) and humans (~40%), and this activation was AMP-activated protein kinase independent. Rac1 inhibition reduced contraction-stimulated glucose uptake in mouse muscle by 55% in soleus and by 20-58% in extensor digitorum longus (EDL; P contraction-stimulated increment in glucose uptake was decreased by 27% (P = 0.1) and 40% (P muscles, respectively, of muscle-specific inducible Rac1 knockout mice. Furthermore, depolymerization of the actin cytoskeleton decreased contraction-stimulated glucose uptake by 100% and 62% (P muscles, respectively. These are the first data to show that Rac1 is activated during muscle contraction in murine and human skeletal muscle and suggest that Rac1 and possibly the actin cytoskeleton are novel regulators of contraction-stimulated glucose uptake.

  19. 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

  20. Skeletal muscle glucose uptake during contraction is regulated by nitric oxide and ROS independently of AMPK.

    Science.gov (United States)

    Merry, Troy L; Steinberg, Gregory R; Lynch, Gordon S; McConell, Glenn K

    2010-03-01

    Reactive oxygen species (ROS) and nitric oxide (NO) have been implicated in the regulation of skeletal muscle glucose uptake during contraction, and there is evidence that they do so via interaction with AMP-activated protein kinase (AMPK). In this study, we tested the hypothesis that ROS and NO regulate skeletal muscle glucose uptake during contraction via an AMPK-independent mechanism. Isolated extensor digitorum longus (EDL) and soleus muscles from mice that expressed a muscle-specific kinase dead AMPKalpha2 isoform (AMPK-KD) and wild-type litter mates (WT) were stimulated to contract, and glucose uptake was measured in the presence or absence of the antioxidant N-acetyl-l-cysteine (NAC) or the nitric oxide synthase (NOS) inhibitor N(G)-monomethyl-l-arginine (l-NMMA). Contraction increased AMPKalpha2 activity in WT but not AMPK-KD EDL muscles. However, contraction increased glucose uptake in the EDL and soleus muscles of AMPK-KD and WT mice to a similar extent. In EDL muscles, NAC and l-NMMA prevented contraction-stimulated increases in oxidant levels (dichloroflourescein fluorescence) and NOS activity, respectively, and attenuated contraction-stimulated glucose uptake in both genotypes to a similar extent. In soleus muscles of AMPK-KD and WT mice, NAC prevented contraction-stimulated glucose uptake and l-NMMA had no effect. This is likely attributed to the relative lack of neuronal NOS in the soleus muscles compared with EDL muscles. Contraction increased AMPKalpha Thr(172) phosphorylation in EDL and soleus muscles of WT but not AMPK-KD mice, and this was not affected by NAC or l-NMMA treatment. In conclusion, ROS and NO are involved in regulating skeletal muscle glucose uptake during contraction via an AMPK-independent mechanism.

  1. On Using Model Populations to Determine Mechanical Properties of Skeletal Muscle. Application to Concentric Contraction Simulation.

    Science.gov (United States)

    Sierra, M; Miana-Mena, F J; Calvo, B; Muñoz, M J; Rodríguez, J F; Grasa, J

    2015-10-01

    In the field of computational biomechanics, the experimental evaluation of the material properties is crucial for the development of computational models that closely reproduce real organ systems. When simulations of muscle tissue are concerned, stress/strain relations for both passive and active behavior are required. These experimental relations usually exhibit certain variability. In this study, a set of material parameters involved in a 3D skeletal muscle model are determined by using a system biology approach in which the parameters are randomly varied leading to a population of models. Using a set of experimental results from an animal model, a subset of the entire population of models was selected. This reduced population predicted the mechanical response within the window of experimental observations. Hence, a range of model parameters, instead of a single set of them, was determined. Rat Tibialis Anterior muscle was selected for this study. Muscles ([Formula: see text]) were activated through the sciatic nerve and during contraction the tissue pulled a weight fixed to the distal tendon (concentric contraction). Three different weights 1, 2 and 3 N were used and the time course of muscle stretch was analyzed obtaining values of (mean [Formula: see text] standard deviation): [Formula: see text], [Formula: see text] and [Formula: see text] respectively. A paired two-sided sign rank test showed significant differences between the muscle response for the three weights ([Formula: see text]). This study shows that the Monte Carlo method could be used for determine muscle characteristic parameters considering the variability of the experimental population.

  2. 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)

  3. In situ microdialysis of intramuscular prostaglandin and thromboxane in contracting skeletal muscle in humans

    DEFF Research Database (Denmark)

    Karamouzis, M; Langberg, Henning; Skovgaard, D

    2001-01-01

    Arachidonic acid metabolites, especially prostacyclin I2, are regulators of vascular tone, and may be released from contracting muscle. In the present study, the influence of exercise on accumulation of prostaglandins and thromboxane in skeletal muscle was determined by the use of microdialysis...

  4. Rac1 Is a Novel Regulator of Contraction-Stimulated Glucose Uptake in Skeletal Muscle

    Science.gov (United States)

    Sylow, Lykke; Jensen, Thomas E.; Kleinert, Maximilian; Mouatt, Joshua R.; Maarbjerg, Stine J.; Jeppesen, Jacob; Prats, Clara; Chiu, Tim T.; Boguslavsky, Shlomit; Klip, Amira; Schjerling, Peter; Richter, Erik A.

    2013-01-01

    In skeletal muscle, the actin cytoskeleton-regulating GTPase, Rac1, is necessary for insulin-dependent GLUT4 translocation. Muscle contraction increases glucose transport and represents an alternative signaling pathway to insulin. Whether Rac1 is activated by muscle contraction and regulates contraction-induced glucose uptake is unknown. Therefore, we studied the effects of in vivo exercise and ex vivo muscle contractions on Rac1 signaling and its regulatory role in glucose uptake in mice and humans. Muscle Rac1-GTP binding was increased after exercise in mice (∼60–100%) and humans (∼40%), and this activation was AMP-activated protein kinase independent. Rac1 inhibition reduced contraction-stimulated glucose uptake in mouse muscle by 55% in soleus and by 20–58% in extensor digitorum longus (EDL; P Rac1 knockout mice. Furthermore, depolymerization of the actin cytoskeleton decreased contraction-stimulated glucose uptake by 100% and 62% (P Rac1 is activated during muscle contraction in murine and human skeletal muscle and suggest that Rac1 and possibly the actin cytoskeleton are novel regulators of contraction-stimulated glucose uptake. PMID:23274900

  5. CaMKII regulates contraction- but not insulin-induced glucose uptake in mouse skeletal muscle.

    Science.gov (United States)

    Witczak, Carol A; Jessen, Niels; Warro, Daniel M; Toyoda, Taro; Fujii, Nobuharu; Anderson, Mark E; Hirshman, Michael F; Goodyear, Laurie J

    2010-06-01

    Studies using chemical inhibitors have suggested that the Ca(2+)-sensitive serine/threonine kinase Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is a key regulator of both insulin- and contraction-stimulated glucose uptake in skeletal muscle. However, due to nonspecificity of these inhibitors, the specific role that CaMKII may play in the regulation of glucose uptake is not known. We sought to determine whether specific inhibition of CaMKII impairs insulin- and/or contraction-induced glucose uptake in mouse skeletal muscle. Expression vectors containing green fluorescent protein conjugated to a CaMKII inhibitory (KKALHRQEAVDCL) or control (KKALHAQERVDCL) peptide were transfected into tibialis anterior muscles by in vivo electroporation. After 1 wk, muscles were assessed for peptide expression, CaMK activity, insulin- and contraction-induced 2-[(3)H]deoxyglucose uptake, glycogen concentrations, and changes in intracellular signaling proteins. Expression of the CaMKII inhibitory peptide decreased muscle CaMK activity approximately 35% compared with control peptide. Insulin-induced glucose uptake was not changed in muscles expressing the inhibitory peptide. In contrast, expression of the inhibitory peptide significantly decreased contraction-induced muscle glucose uptake (approximately 30%). Contraction-induced decreases in muscle glycogen were not altered by the inhibitory peptide. The CaMKII inhibitory peptide did not alter expression of the glucose transporter GLUT4 and did not impair contraction-induced increases in the phosphorylation of AMP-activated protein kinase (Thr(172)) or TBC1D1/TBC1D4 on phospho-Akt substrate sites. These results demonstrate that CaMKII does not regulate insulin-stimulated glucose uptake in skeletal muscle. However, CaMKII plays a critical role in the regulation of contraction-induced glucose uptake in mouse skeletal muscle.

  6. 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....

  7. (-)-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.

  8. Contraction and AICAR stimulate IL-6 vesicle depletion from skeletal muscle fibers in vivo.

    Science.gov (United States)

    Lauritzen, Hans P M M; Brandauer, Josef; Schjerling, Peter; Koh, Ho-Jin; Treebak, Jonas T; Hirshman, Michael F; Galbo, Henrik; Goodyear, Laurie J

    2013-09-01

    Recent studies suggest that interleukin 6 (IL-6) is released from contracting skeletal muscles; however, the cellular origin, secretion kinetics, and signaling mechanisms regulating IL-6 secretion are unknown. To address these questions, we developed imaging methodology to study IL-6 in fixed mouse muscle fibers and in live animals in vivo. Using confocal imaging to visualize endogenous IL-6 protein in fixed muscle fibers, we found IL-6 in small vesicle structures distributed throughout the fibers under basal (resting) conditions. To determine the kinetics of IL-6 secretion, intact quadriceps muscles were transfected with enhanced green fluorescent protein (EGFP)-tagged IL-6 (IL-6-EGFP), and 5 days later anesthetized mice were imaged before and after muscle contractions in situ. Contractions decreased IL-6-EGFP-containing vesicles and protein by 62% (P contraction. However, contraction-mediated IL-6-EGFP reduction was normal in muscle-specific AMP-activated protein kinase (AMPK) α2-inactive transgenic mice. In contrast, the AMPK activator AICAR decreased IL-6-EGFP vesicles, an effect that was inhibited in the transgenic mice. In conclusion, resting skeletal muscles contain IL-6-positive vesicles that are expressed throughout myofibers. Contractions stimulate the rapid reduction of IL-6 in myofibers, occurring through an AMPKα2-independent mechanism. This novel imaging methodology clearly establishes IL-6 as a contraction-stimulated myokine and can be used to characterize the secretion kinetics of other putative myokines.

  9. High glycogen levels enhance glycogen breakdown in isolated contracting skeletal muscle

    DEFF Research Database (Denmark)

    Richter, Erik; Galbo, H

    1986-01-01

    and after 15 min of intermittent electrical muscle stimulation. Before stimulation, glycogen was higher in rats that swam on the preceding day (supercompensated rats) compared with controls. During muscle contractions, glycogen breakdown in fast-twitch red and white fibers was larger in supercompensated...

  10. 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.

  11. Kinetics of contraction-induced GLUT4 translocation in skeletal muscle fibers from living mice

    DEFF Research Database (Denmark)

    Lauritzen, Hans Peter M. Mortensen; Galbo, Henrik; Toyoda, Taro

    2010-01-01

    Exercise is an important strategy for the treatment of type 2 diabetes. This is due in part to an increase in glucose transport that occurs in the working skeletal muscles. Glucose transport is regulated by GLUT4 translocation in muscle, but the molecular machinery mediating this process is poorly...... understood. The purpose of this study was to 1) use a novel imaging system to elucidate the kinetics of contraction-induced GLUT4 translocation in skeletal muscle and 2) determine the function of AMP-activated protein kinase alpha2 (AMPKalpha2) in this process....

  12. Heat production during contraction in skeletal muscle of hypothyroid mice

    Energy Technology Data Exchange (ETDEWEB)

    Leijendekker, W.J.; van Hardeveld, C.; Elzinga, G. (Free Univ., Amsterdam (Netherlands))

    1987-08-01

    The effect of hypothyroidism on tension-independent and -dependent heat produced during a twitch and a tetanic contraction of extensor digitorum longus (EDL) and soleus muscle of mice was examined. The amount of heat produced during a twitch and the rate of heat development during a tetanus of EDL and soleus were measured at and above optimal length. The effect of hypothyroidism on force production was <30%. Straight lines were used to fit the relation between heat production and force. Hypothyroidism significantly decreases tension-independent heat during contraction of EDL and soleus muscle. Because the tension-independent heat is considered to be related to the Ca{sup 2+} cycling, these findings suggest that ATP splitting due to the Ca{sup 2+} cycling is reduced in hypothyroid mice. This conclusion was strengthened by the observation that the oxalate-supported {sup 45}Ca{sup 2+}-uptake activity and {sup 45}Ca{sup 2+}-loading capacity of muscle homogenates from hypothyroid mice were reduced, respectively, to 51 and to 65% in soleus and to 63 and 73% in EDL muscle as compared with euthyroid mice. The tension-dependent rate of heat development during a tetanus was also decreased in soleus muscle of hypothyroid mice. This suggests a lower rate of ATP hydrolysis related to cross-bridge cycling in this muscle due to the hypothyroid state.

  13. A DIC Based Technique to Measure the Contraction of a Skeletal Muscle Engineered Tissue

    Directory of Open Access Journals (Sweden)

    Emanuele Rizzuto

    2016-01-01

    Full Text Available Tissue engineering is a multidisciplinary science based on the application of engineering approaches to biologic tissue formation. Engineered tissue internal organization represents a key aspect to increase biofunctionality before transplant and, as regarding skeletal muscles, the potential of generating contractile forces is dependent on the internal fiber organization and is reflected by some macroscopic parameters, such as the spontaneous contraction. Here we propose the application of digital image correlation (DIC as an independent tool for an accurate and noninvasive measurement of engineered muscle tissue spontaneous contraction. To validate the proposed technique we referred to the X-MET, a promising 3-dimensional model of skeletal muscle. The images acquired through a high speed camera were correlated with a custom-made algorithm and the longitudinal strain predictions were employed for measuring the spontaneous contraction. The spontaneous contraction reference values were obtained by studying the force response. The relative error between the spontaneous contraction frequencies computed in both ways was always lower than 0.15%. In conclusion, the use of a DIC based system allows for an accurate and noninvasive measurement of biological tissues’ spontaneous contraction, in addition to the measurement of tissue strain field on any desired region of interest during electrical stimulation.

  14. 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.

  15. 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...

  16. Kinetics of contraction-induced GLUT4 translocation in skeletal muscle fibers from living mice

    DEFF Research Database (Denmark)

    Lauritzen, Hans Peter M. Mortensen; Galbo, Henrik; Toyoda, Taro

    2010-01-01

    Exercise is an important strategy for the treatment of type 2 diabetes. This is due in part to an increase in glucose transport that occurs in the working skeletal muscles. Glucose transport is regulated by GLUT4 translocation in muscle, but the molecular machinery mediating this process is poorl...... understood. The purpose of this study was to 1) use a novel imaging system to elucidate the kinetics of contraction-induced GLUT4 translocation in skeletal muscle and 2) determine the function of AMP-activated protein kinase alpha2 (AMPKalpha2) in this process.......Exercise is an important strategy for the treatment of type 2 diabetes. This is due in part to an increase in glucose transport that occurs in the working skeletal muscles. Glucose transport is regulated by GLUT4 translocation in muscle, but the molecular machinery mediating this process is poorly...

  17. Vascular Function and Regulation of Blood Flow in Resting and Contracting Skeletal Muscle

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin

    importance. The present work provides new insight in to vasodilator interactions important for exercise hyperemia and sheds light on mechanisms important for vascular function and regulation of skeletal muscle blood flow in essential hypertension (high blood pressure) and aging and identifies mechanisms......The precise matching of blood flow, oxygen delivery and metabolism is essential as it ensures that any increase in muscle work is precisely matched by increases in oxygen delivery. Therefore, understanding the control mechanisms of skeletal muscle blood flow regulation is of great biological...... in the regulation of exercise hyperemia. Furthermore, blood flow to contracting leg skeletal muscles is reduced both in essential hypertension and with aging. The potential difference in vasoactive system(s) responsible for the reduction in blood flow in the two conditions is in agreement with the suggestion...

  18. Contraction regulates site-specific phosphorylation of TBC1D1 in skeletal muscle.

    Science.gov (United States)

    Vichaiwong, Kanokwan; Purohit, Suneet; An, Ding; Toyoda, Taro; Jessen, Niels; Hirshman, Michael F; Goodyear, Laurie J

    2010-10-15

    TBC1D1 (tre-2/USP6, BUB2, cdc16 domain family member 1) is a Rab-GAP (GTPase-activating protein) that is highly expressed in skeletal muscle, but little is known about TBC1D1 regulation and function. We studied TBC1D1 phosphorylation on three predicted AMPK (AMP-activated protein kinase) phosphorylation sites (Ser231, Ser660 and Ser700) and one predicted Akt phosphorylation site (Thr590) in control mice, AMPKα2 inactive transgenic mice (AMPKα2i TG) and Akt2-knockout mice (Akt2 KO). Muscle contraction significantly increased TBC1D1 phosphorylation on Ser231 and Ser660, tended to increase Ser700 phosphorylation, but had no effect on Thr590. AICAR (5-aminoimidazole-4-carboxyamide ribonucleoside) also increased phosphorylation on Ser231, Ser660 and Ser700, but not Thr590, whereas insulin only increased Thr590 phosphorylation. Basal and contraction-stimulated TBC1D1 Ser231, Ser660 and Ser700 phosphorylation were greatly reduced in AMPKα2i TG mice, although contraction still elicited a small increase in phosphorylation. Akt2 KO mice had blunted insulin-stimulated TBC1D1 Thr590 phosphorylation. Contraction-stimulated TBC1D1 Ser231 and Ser660 phosphorylation were normal in high-fat-fed mice. Glucose uptake in vivo was significantly decreased in tibialis anterior muscles overexpressing TBC1D1 mutated on four predicted AMPK phosphorylation sites. In conclusion, contraction causes site-specific phosphorylation of TBC1D1 in skeletal muscle, and TBC1D1 phosphorylation on AMPK sites regulates contraction-stimulated glucose uptake. AMPK and Akt regulate TBC1D1 phosphorylation, but there must be additional upstream kinases that mediate TBC1D1 phosphorylation in skeletal muscle.

  19. Nonlinear deformation of skeletal muscles in a passive state and in isotonic contraction

    Science.gov (United States)

    Shil'ko, S. V.; Chernous, D. A.; Pleskachevskii, Yu. M.

    2012-07-01

    A procedure for a two-level modeling of deformation of skeletal muscles is offered. Based on a phenomenological model of an individual muscle fiber, consisting of a viscous, a contractive, and two nonlinearly elastic elements (the first level), various means for describing a skeletal muscle as a whole (the second, macroscopic level) are considered. A method for identification of a muscle model by utilizing experimental elongation diagrams in a passive state and in isotonic contraction is put forward. The results of a biomechanical analysis are compared with known experimental data for the isotonic and isometric activation regimes of tailor's muscle of a frog. It is established that preferable is the description of a muscle that takes into account the different lengths of muscle fibers and their twist.

  20. Heat production during contraction in skeletal muscle of hypothyroid mice

    International Nuclear Information System (INIS)

    Leijendekker, W.J.; van Hardeveld, C.; Elzinga, G.

    1987-01-01

    The effect of hypothyroidism on tension-independent and -dependent heat produced during a twitch and a tetanic contraction of extensor digitorum longus (EDL) and soleus muscle of mice was examined. The amount of heat produced during a twitch and the rate of heat development during a tetanus of EDL and soleus were measured at and above optimal length. The effect of hypothyroidism on force production was 2+ cycling, these findings suggest that ATP splitting due to the Ca 2+ cycling is reduced in hypothyroid mice. This conclusion was strengthened by the observation that the oxalate-supported 45 Ca 2+ -uptake activity and 45 Ca 2+ -loading capacity of muscle homogenates from hypothyroid mice were reduced, respectively, to 51 and to 65% in soleus and to 63 and 73% in EDL muscle as compared with euthyroid mice. The tension-dependent rate of heat development during a tetanus was also decreased in soleus muscle of hypothyroid mice. This suggests a lower rate of ATP hydrolysis related to cross-bridge cycling in this muscle due to the hypothyroid state

  1. A novel three-filament model of force generation in eccentric contraction of skeletal muscles.

    Directory of Open Access Journals (Sweden)

    Gudrun Schappacher-Tilp

    Full Text Available We propose and examine a three filament model of skeletal muscle force generation, thereby extending classical cross-bridge models by involving titin-actin interaction upon active force production. In regions with optimal actin-myosin overlap, the model does not alter energy and force predictions of cross-bridge models for isometric contractions. However, in contrast to cross-bridge models, the three filament model accurately predicts history-dependent force generation in half sarcomeres for eccentric and concentric contractions, and predicts the activation-dependent forces for stretches beyond actin-myosin filament overlap.

  2. Effects of adenosine triphosphate concentration on motor force regulation during skeletal muscle contraction

    Science.gov (United States)

    Wei, J.; Dong, C.; Chen, B.

    2017-04-01

    We employ a mechanical model of sarcomere to quantitatively investigate how adenosine triphosphate (ATP) concentration affects motor force regulation during skeletal muscle contraction. Our simulation indicates that there can be negative cross-bridges resisting contraction within the sarcomere and higher ATP concentration would decrease the resistance force from negative cross-bridges by promoting their timely detachment. It is revealed that the motor force is well regulated only when ATP concentration is above a certain level. These predictions may provide insights into the role of ATP in regulating coordination among multiple motors.

  3. Low Po2 conditions induce reactive oxygen species formation during contractions in single skeletal muscle fibers

    Science.gov (United States)

    Shiah, Amy; Roberts, William J.; Chien, Michael T.; Wagner, Peter D.; Hogan, Michael C.

    2013-01-01

    Contractions in whole skeletal muscle during hypoxia are known to generate reactive oxygen species (ROS); however, identification of real-time ROS formation within isolated single skeletal muscle fibers has been challenging. Consequently, there is no convincing evidence showing increased ROS production in intact contracting fibers under low Po2 conditions. Therefore, we hypothesized that intracellular ROS generation in single contracting skeletal myofibers increases during low Po2 compared with a value approximating normal resting Po2. Dihydrofluorescein was loaded into single frog (Xenopus) fibers, and fluorescence was used to monitor ROS using confocal microscopy. Myofibers were exposed to two maximal tetanic contractile periods (1 contraction/3 s for 2 min, separated by a 60-min rest period), each consisting of one of the following treatments: high Po2 (30 Torr), low Po2 (3–5 Torr), high Po2 with ebselen (antioxidant), or low Po2 with ebselen. Ebselen (10 μM) was administered before the designated contractile period. ROS formation during low Po2 treatment was greater than during high Po2 treatment, and ebselen decreased ROS generation in both low- and high-Po2 conditions (P Po2. Force was reduced >30% for each condition except low Po2 with ebselen, which only decreased ∼15%. We concluded that single myofibers under low Po2 conditions develop accelerated and more oxidative stress than at Po2 = 30 Torr (normal human resting Po2). Ebselen decreases ROS formation in both low and high Po2, but only mitigates skeletal muscle fatigue during reduced Po2 conditions. PMID:23576612

  4. Intramuscular fatty acid metabolism in contracting and non-contracting human skeletal muscle

    DEFF Research Database (Denmark)

    Sacchetti, M; Saltin, B; Osada, T

    2002-01-01

    The present study was undertaken to investigate the fate of blood-borne non-esterified fatty acids (NEFA) entering contracting and non-contracting knee extensor muscles of healthy young individuals. [U-(13)C]-palmitate was infused into a forearm vein during 5 h of one-legged knee extensor exercis...... and degraded and that the metabolic fate of plasma NEFA entering the muscle is influenced by muscle contraction, so that a higher proportion is directed towards oxidation at the expense of storage in mTAG.......The present study was undertaken to investigate the fate of blood-borne non-esterified fatty acids (NEFA) entering contracting and non-contracting knee extensor muscles of healthy young individuals. [U-(13)C]-palmitate was infused into a forearm vein during 5 h of one-legged knee extensor exercise.......05) in the contracting muscle, whereas it was unchanged in the non-contracting muscle. The uptake of plasma NEFA, as well as the proportion directed towards oxidation, was higher in the exercising compared to the non-exercising leg, whereas the rate of palmitate incorporation into mTAG was fourfold lower (0.70 +/- 0...

  5. Accelerated 4D phase contrast MRI in skeletal muscle contraction.

    Science.gov (United States)

    Mazzoli, Valentina; Gottwald, Lukas M; Peper, Eva S; Froeling, Martijn; Coolen, Bram F; Verdonschot, Nico; Sprengers, Andre M; van Ooij, Pim; Strijkers, Gustav J; Nederveen, Aart J

    2018-03-05

    3D time-resolved (4D) phase contrast MRI can be used to study muscle contraction. However, 3D coverage with sufficient spatiotemporal resolution can only be achieved by interleaved acquisitions during many repetitions of the motion task, resulting in long scan times. The aim of this study was to develop a compressed sensing accelerated 4D phase contrast MRI technique for quantification of velocities and strain rate of the muscles in the lower leg during active plantarflexion/dorsiflexion. Nine healthy volunteers were scanned during active dorsiflexion/plantarflexion task. For each volunteer, we acquired a reference scan, as well as 4 different accelerated scans (k-space undersampling factors: 3.14X, 4.09X, 4.89X, and 6.41X) obtained using Cartesian Poisson disk undersampling schemes. The data was reconstructed using a compressed sensing pipeline. For each scan, velocity and strain rate values were quantified in the gastrocnemius lateralis, gastrocnemius medialis, tibialis anterior, and soleus. No significant differences in velocity values were observed as a function acceleration factor in the investigated muscles. The strain rate calculation resulted in one positive (s + ) and one negative (s - ) eigenvalue, whereas the third eigenvalue (s 3 ) was consistently 0 for all the acquisitions. No significant differences were observed for the strain rate eigenvalues as a function of acceleration factor. Data undersampling combined with compressed sensing reconstruction allowed obtainment of time-resolved phase contrast acquisitions with 3D coverage and quantitative information comparable to the reference scan. The 3D sensitivity of the method can help in understanding the connection between muscle architecture and muscle function in future studies. © 2018 International Society for Magnetic Resonance in Medicine.

  6. Tetanic contraction induces enhancement of fatigability and sarcomeric damage in atrophic skeletal muscle and its underlying molecular mechanisms.

    Science.gov (United States)

    Yu, Zhi-Bin

    2013-11-01

    Muscle unloading due to long-term exposure of weightlessness or simulated weightlessness causes atrophy, loss of functional capacity, impaired locomotor coordination, and decreased resistance to fatigue in the antigravity muscles of the lower limbs. Besides reducing astronauts' mobility in space and on returning to a gravity environment, the molecular mechanisms for the adaptation of skeletal muscle to unloading also play an important medical role in conditions such as disuse and paralysis. The tail-suspended rat model was used to simulate the effects of weightlessness on skeletal muscles and to induce muscle unloading in the rat hindlimb. Our series studies have shown that the maximum of twitch tension and the twitch duration decreased significantly in the atrophic soleus muscles, the maximal tension of high-frequency tetanic contraction was significantly reduced in 2-week unloaded soleus muscles, however, the fatigability of high-frequency tetanic contraction increased after one week of unloading. The maximal isometric tension of intermittent tetanic contraction at optimal stimulating frequency did not alter in 1- and 2-week unloaded soleus, but significantly decreased in 4-week unloaded soleus. The 1-week unloaded soleus, but not extensor digitorum longus (EDL), was more susceptible to fatigue during intermittent tetanic contraction than the synchronous controls. The changes in K+ channel characteristics may increase the fatigability during high-frequency tetanic contraction in atrophic soleus muscles. High fatigability of intermittent tetanic contraction may be involved in enhanced activity of sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) and switching from slow to fast isoform of myosin heavy chain, tropomyosin, troponin I and T subunit in atrophic soleus muscles. Unloaded soleus muscle also showed a decreased protein level of neuronal nitric oxide synthase (nNOS), and the reduction in nNOS-derived NO increased frequency of calcium sparks and elevated

  7. Skeletal muscle metabolism in hypokinetic rats

    Science.gov (United States)

    Tischler, Marc E.

    1993-01-01

    This grant focused on the mechanisms of metabolic changes associated with unweighting atrophy and reduced growth of hind limb muscles of juvenile rats. Metabolic studies included a number of different areas. Amino acid metabolic studies placed particular emphasis on glutamine and branched-chain amino acid metabolism. These studies were an outgrowth of understanding stress effects and the role of glucocorticoids in these animals. Investigations on protein metabolism were largely concerned with selective loss of myofibrillar proteins and the role of muscle proteolysis. These investigations lead to finding important differences from denervation and atrophy and to define the roles of cytosolic versus lysosomal proteolysis in these atrophy models. A major outgrowth of these studies was demonstrating an ability to prevent atrophy of the unweighted muscle for at least 24 hours. A large amount of work concentrated on carbohydrate metabolism and its regulation by insulin and catecholamines. Measurements focused on glucose transport, glycogen metabolism, and glucose oxidation. The grant was used to develop an important new in situ approach for studying protein metabolism, glucose transport, and hormonal effects which involves intramuscular injection of various agents for up to 24 hours. Another important consequence of this project was the development and flight of Physiological-Anatomical Rodent Experiment-1 (PARE-1), which was launched aboard Space Shuttle Discovery in September 1991. Detailed descriptions of these studies can be found in the 30 peer-reviewed publications, 15 non-reviewed publications, 4 reviews and 33 abstracts (total 82 publications) which were or are scheduled to be published as a result of this project. A listing of these publications grouped by area (i.e. amino acid metabolism, protein metabolism, carbohydrate metabolism, and space flight studies) are included.

  8. 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.

  9. Regulation of Contraction by the Thick Filaments in Skeletal Muscle.

    Science.gov (United States)

    Irving, Malcolm

    2017-12-19

    Contraction of skeletal muscle cells is initiated by a well-known signaling pathway. An action potential in a motor nerve triggers an action potential in a muscle cell membrane, a transient increase of intracellular calcium concentration, binding of calcium to troponin in the actin-containing thin filaments, and a structural change in the thin filaments that allows myosin motors from the thick filaments to bind to actin and generate force. This calcium/thin filament mediated pathway provides the "START" signal for contraction, but it is argued that the functional response of the muscle cell, including the speed of its contraction and relaxation, adaptation to the external load, and the metabolic cost of contraction is largely determined by additional mechanisms. This review considers the role of the thick filaments in those mechanisms, and puts forward a paradigm for the control of contraction in skeletal muscle in which both the thick and thin filaments have a regulatory function. The OFF state of the thick filament is characterized by helical packing of most of the myosin head or motor domains on the thick filament surface in a conformation that makes them unavailable for actin binding or ATP hydrolysis, although a small fraction of the myosin heads are constitutively ON. The availability of the majority fraction of the myosin heads for contraction is controlled in part by the external load on the muscle, so that these heads only attach to actin and hydrolyze ATP when they are required. This phenomenon seems to be the major determinant of the well-known force-velocity relationship of muscle, and controls the metabolic cost of contraction. The regulatory state of the thick filament also seems to control the dynamics of both muscle activation and relaxation. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  10. Skeletal muscle contraction in protecting joints and bones by absorbing mechanical impacts

    Science.gov (United States)

    Rudenko, O. V.; Tsyuryupa, S.; Sarvazyan, A.

    2016-09-01

    We have previously hypothesized that the dissipation of mechanical energy of external impact is a fundamental function of skeletal muscle in addition to its primary function to convert chemical energy into mechanical energy. In this paper, a mathematical justification of this hypothesis is presented. First, a simple mechanical model, in which the muscle is considered as a simple Hookean spring, is considered. This analysis serves as an introduction to the consideration of a biomechanical model taking into account the molecular mechanism of muscle contraction, kinetics of myosin bridges, sarcomere dynamics, and tension of muscle fibers. It is shown that a muscle behaves like a nonlinear and adaptive spring tempering the force of impact and increasing the duration of the collision. The temporal profiles of muscle reaction to the impact as functions of the levels of muscle contraction, durations of the impact front, and the time constants of myosin bridges closing, are obtained. The absorption of mechanical shock energy is achieved due to the increased viscoelasticity of the contracting skeletal muscle. Controlling the contraction level allows for the optimization of the stiffness and viscosity of the muscle necessary for the protection of the joints and bones.

  11. Multivariate analysis of electrical impedance spectra for relaxed and contracted skeletal muscle

    International Nuclear Information System (INIS)

    Zagar, T; Krizaj, D

    2008-01-01

    Four-electrode impedance spectra of relaxed and contracted muscle biceps brachii were analyzed in an adult human subject over the frequency range from 300 Hz to 75 kHz. A feasibility of the principal component analysis of bioimpedance measurement for the evaluation of skeletal muscle contractile state was examined. The principal components score plots show a data grouping of the impedance spectra from the two muscle groups. The classification was performed using a soft independent modeling of class analogy (SIMCA) method. The data set comprised 32 samples (16 samples of contracted muscle and 16 samples of relaxed muscle). The leave-one-out test of the classification yields about 80% of correctly classified samples (11 samples for contracted and 15 samples for relaxed muscle)

  12. An Estimating Method of Contractile State Changes Come From Continuous Isometric Contraction of Skeletal Muscle

    Energy Technology Data Exchange (ETDEWEB)

    Park, H.J.; Lee, S.J. [Wonkwang University, Iksan (Korea)

    2003-01-01

    In this study was proposed that a new estimating method for investigation of contractile state changes which generated from continuous isometric contraction of skeletal muscle. The physiological changes (EMG, ECG) and the psychological changes by CNS(central nervous system) were measured by experiments, while the muscle of subjects contracted continuously with isometric contraction in constant load. The psychological changes were represented as three-step-change named 'fatigue', 'pain' and 'sick(greatly pain)' from oral test, and the method which compared physiological change with psychological change on basis of these three steps was developed. The result of analyzing the physiological signals, EMG and ECG signal changes were observed at the vicinity of judging point in time of psychological changes. Namely, it is supposed that contractile states have three kind of states pattern (stable, fatigue, pain) instead of two states (stable, fatigue). (author). 24 refs., 7 figs.

  13. 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.

  14. Identification of CCL5/RANTES as a novel contraction-reducible myokine in mouse skeletal muscle.

    Science.gov (United States)

    Ishiuchi, Yuri; Sato, Hitoshi; Komatsu, Narumi; Kawaguchi, Hideo; Matsuwaki, Takashi; Yamanouchi, Keitaro; Nishihara, Masugi; Nedachi, Taku

    2018-03-17

    Skeletal muscle is an endocrine organ that secretes several proteins, which are collectively termed myokines. Although many studies suggest that exercise regulates myokine secretion, the underlying mechanisms remain unclear and all the exercise-dependent myokines have not yet been identified. Therefore, in this study, we attempted to identify novel exercise-dependent myokines by using our recently developed in vitro contractile model. Differentiated C2C12 myotubes were cultured with or without electrical pulse stimulation (EPS) for 24 h to induce cell contraction, and the myokines secreted in conditioned medium were analyzed using a cytokine array. Although most myokine secretions were not affected by EPS, the secretion of Chemokine (C-C motif) ligand 5 (CCL5) (regulated on activation, normal T cell expressed and secreted (RANTES)) was significantly reduced by EPS. This was further confirmed by ELISA and quantitative PCR. Contraction-dependent calcium transients and activation of 5'-AMP activating protein kinase (AMPK) appears to be involved in this decrease, as the chelating Ca 2+ by EGTA blocked contraction-dependent CCL5 reduction, whereas the pharmacological activation of AMPK significantly reduced it. However, Ccl5 gene expression was increased by AMPK activation, suggesting that AMPK-dependent CCL5 decrease occurred via post-transcriptional regulation. Finally, mouse experiments revealed that voluntary wheel-running exercise reduced serum CCL5 levels and Ccl5 gene expression in the fast-twitch muscles. Overall, our study provides the first evidence of an exercise-reducible myokine, CCL5, in the mouse skeletal muscle. Although further studies are required to understand the precise roles of the skeletal muscle cell contraction-induced decrease in CCL5, this decrease may explain some exercise-dependent physiological changes such as those in immune responses. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Skeletal myofiber VEGF regulates contraction-induced perfusion and exercise capacity but not muscle capillarity in adult mice.

    Science.gov (United States)

    Knapp, Amy E; Goldberg, Daniel; Delavar, Hamid; Trisko, Breanna M; Tang, Kechun; Hogan, Michael C; Wagner, Peter D; Breen, Ellen C

    2016-07-01

    A single bout of exhaustive exercise signals expression of vascular endothelial growth factor (VEGF) in the exercising muscle. Previous studies have reported that mice with life-long deletion of skeletal myofiber VEGF have fewer capillaries and a severe reduction in endurance exercise. However, in adult mice, VEGF gene deletion conditionally targeted to skeletal myofibers limits exercise capacity without evidence of capillary regression. To explain this, we hypothesized that adult skeletal myofiber VEGF acutely regulates skeletal muscle perfusion during muscle contraction. A tamoxifen-inducible skeletal myofiber-specific VEGF gene deletion mouse (skmVEGF-/-) was used to reduce skeletal muscle VEGF protein by 90% in adult mice. Three weeks after inducing deletion of the skeletal myofiber VEGF gene, skmVEGF-/- mice exhibited diminished maximum running speed (-10%, P Contraction-induced perfusion measured by optical imaging during a period of electrically stimulated muscle contraction was 85% lower in skmVEGF-/- than control mice. No evidence of capillary rarefication was detected in the soleus, gastrocnemius, and extensor digitorum longus (EDL) up to 8 wk after tamoxifen-induced VEGF ablation, and contractility and fatigue resistance of the soleus measured ex vivo were also unchanged. The force-frequency of the EDL showed a small right shift, but fatigue resistance did not differ between EDL from control and skmVEGF-/- mice. These data suggest myofiber VEGF is required for regulating perfusion during periods of contraction and may in this manner affect endurance capacity. Copyright © 2016 the American Physiological Society.

  16. Rac1--a novel regulator of contraction-stimulated glucose uptake in skeletal muscle.

    Science.gov (United States)

    Sylow, Lykke; Møller, Lisbeth L V; Kleinert, Maximilian; Richter, Erik A; Jensen, Thomas E

    2014-12-01

    Muscle contraction stimulates muscle glucose uptake by facilitating translocation of glucose transporter 4 from intracellular locations to the cell surface, which allows for diffusion of glucose into the myofibres. The intracellular mechanisms regulating this process are not well understood. The GTPase Rac1 has, until recently, been investigated only with regard to its involvement in insulin-stimulated glucose uptake. However, we recently found that Rac1 is activated during muscle contraction and exercise in mice and humans. Remarkably, Rac1 seems to be necessary for exercise and contraction-stimulated glucose uptake in skeletal muscle, because muscle-specific Rac1 knockout mice display reduced ex vivo contraction- and in vivo exercise-stimulated glucose uptake. The molecular mechanism by which Rac1 regulates glucose uptake is presently unknown. However, recent studies link Rac1 to the actin cytoskeleton, the small GTPase RalA and/or free radical production, which have previously been shown to be regulators of glucose uptake in muscle. We propose a model in which Rac1 is activated by contraction- and exercise-induced mechanical stress signals and that Rac1 in conjunction with other signalling regulates glucose uptake during muscle contraction and exercise. © 2014 The Authors. Experimental Physiology © 2014 The Physiological Society.

  17. 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

  18. 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

  19. Adenosine concentrations in the interstitium of resting and contracting human skeletal muscle

    DEFF Research Database (Denmark)

    Hellsten, Ylva; Maclean, D.; Rådegran, G.

    1998-01-01

    BACKGROUND: Adenosine has been proposed to be a locally produced regulator of blood flow in skeletal muscle. However, the fundamental questions of to what extent adenosine is formed in skeletal muscle tissue of humans, whether it is present in the interstitium, and where it exerts its vasodilatory...... rest (0.13+/-0.03, 0.07+/-0.03, and 0.07+/-0.02 micromol/L, respectively) to exercise (10 W; 2.00+/-1.32, 2.08+/-1.23, and 1.65+/-0.50 micromol/L, respectively; Pskeletal muscle...... and demonstrates that adenosine and its precursors increase in the exercising muscle interstitium, at a rate associated with intensity of muscle contraction and the magnitude of muscle blood flow....

  20. Connective tissue regeneration in skeletal muscle after eccentric contraction-induced injury.

    Science.gov (United States)

    Mackey, Abigail L; Kjaer, Michael

    2017-03-01

    Human skeletal muscle has the potential to regenerate completely after injury induced under controlled experimental conditions. The events inside the myofibers as they undergo necrosis, followed closely by satellite cell-mediated myogenesis, have been mapped in detail. Much less is known about the adaptation throughout this process of both the connective tissue structures surrounding the myofibers and the fibroblasts, the cells responsible for synthesizing this connective tissue. However, the few studies investigating muscle connective tissue remodeling demonstrate a strong response that appears to be sustained for a long time after the major myofiber responses have subsided. While the use of electrical stimulation to induce eccentric contractions vs. voluntary eccentric contractions appears to lead to a greater extent of myofiber necrosis and regenerative response, this difference is not apparent when the muscle connective tissue responses are compared, although further work is required to confirm this. Pharmacological agents (growth hormone and angiotensin II type I receptor blockers) are considered in the context of accelerating the muscle connective tissue adaptation to loading. Cautioning against this, however, is the association between muscle matrix protein remodeling and protection against reinjury, which suggests that a (so far undefined) period of vulnerability to reinjury may exist during the remodeling phases. The role of individual muscle matrix components and their spatial interaction during adaptation to eccentric contractions is an unexplored field in human skeletal muscle and may provide insight into the optimal timing of rest vs. return to activity after muscle injury. Copyright © 2017 the American Physiological Society.

  1. 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

  2. Modulation effects of cordycepin on the skeletal muscle contraction of toad gastrocnemius muscle.

    Science.gov (United States)

    Yao, Li-Hua; Meng, Wei; Song, Rong-Feng; Xiong, Qiu-Ping; Sun, Wei; Luo, Zhi-Qiang; Yan, Wen-Wen; Li, Yu-Ping; Li, Xin-Ping; Li, Hai-Hang; Xiao, Peng

    2014-03-05

    Isolated toad gastrocnemius muscle is a typical skeletal muscle tissue that is frequently used to study the motor system because it is an important component of the motor system. This study investigates the effects of cordycepin on the skeletal muscle contractile function of isolated toad gastrocnemius muscles by electrical field stimulation. Results showed that cordycepin (20 mg/l to 100 mg/l) significantly decreased the contractile responses in a concentration-dependent manner. Cordycepin (50 mg/l) also produced a rightward shift of the contractile amplitude-stimulation intensity relationship, as indicated by the increases in the threshold stimulation intensity and the saturation stimulation intensity. However, the most notable result was that the maximum amplitude of the muscle contractile force was significantly increased under cordycepin application (122±3.4% of control). This result suggests that the skeletal muscle contractile function and muscle physical fitness to the external stimulation were improved by the decreased response sensitivity in the presence of cordycepin. Moreover, cordycepin also prevented the repetitive stimulation-induced decrease in muscle contractile force and increased the recovery amplitude and recovery ratio of muscle contraction. However, these anti-fatigue effects of cordycepin on muscle contraction during long-lasting muscle activity were absent in Ca2+-free medium or in the presence of all Ca2+ channels blocker (0.4 mM CdCl2). These results suggest that cordycepin can positively affect muscle performance and provide ergogenic and prophylactic benefits in decreasing skeletal muscle fatigue. The mechanisms involving excitation-coupled Ca2+ influxes are strongly recommended.

  3. 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.

  4. Sucrose nonfermenting AMPK-related kinase (SNARK) mediates contraction-stimulated glucose transport in mouse skeletal muscle

    OpenAIRE

    Koh, Ho-Jin; Toyoda, Taro; Fujii, Nobuharu; Jung, Michelle M.; Rathod, Amee; Middelbeek, R. Jan-Willem; Lessard, Sarah J.; Treebak, Jonas T.; Tsuchihara, Katsuya; Esumi, Hiroyasu; Richter, Erik A.; Wojtaszewski, Jørgen F. P.; Hirshman, Michael F.; Goodyear, Laurie J.

    2010-01-01

    The signaling mechanisms that mediate the important effects of contraction to increase glucose transport in skeletal muscle are not well understood, but are known to occur through an insulin-independent mechanism. Muscle-specific knockout of LKB1, an upstream kinase for AMPK and AMPK-related protein kinases, significantly inhibited contraction-stimulated glucose transport. This finding, in conjunction with previous studies of ablated AMPKα2 activity showing no effect on contraction-stimulated...

  5. 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.

  6. Cholesterol Removal from Adult Skeletal Muscle impairs Excitation-Contraction Coupling and Aging reduces Caveolin-3 and alters the Expression of other Triadic Proteins

    Directory of Open Access Journals (Sweden)

    Genaro eBarrientos

    2015-04-01

    Full Text Available Cholesterol and caveolin are integral membrane components that modulate the function/location of many cellular proteins. Skeletal muscle fibers, which have unusually high cholesterol levels in transverse tubules, express the caveolin-3 isoform but its association with transverse tubules remains contentious. Cholesterol removal impairs excitation-contraction coupling in amphibian and mammalian fetal skeletal muscle fibers. Here, we show that treating single muscle fibers from adult mice with the cholesterol removing agent methyl-β-cyclodextrin decreased fiber cholesterol by 26%, altered the location pattern of caveolin-3 and of the voltage dependent calcium channel Cav1.1, and suppressed or reduced electrically evoked Ca2+ transients without affecting membrane integrity or causing sarcoplasmic reticulum calcium depletion. We found that transverse tubules from adult muscle and triad fractions that contain ~10% attached transverse tubules, but not sarcoplasmic reticulum membranes, contained caveolin-3 and Cav1.1; both proteins partitioned into detergent-resistant membrane fractions highly enriched in cholesterol. Aging entails significant deterioration of skeletal muscle function. We found that triad fractions from aged rats had similar cholesterol and RyR1 protein levels compared to triads from young rats, but had lower caveolin-3 and glyceraldehyde 3-phosphate dehydrogenase and increased Na+/K+-ATPase protein levels. Both triad fractions had comparable NADPH oxidase (NOX activity and protein content of NOX2 subunits (p47phox and gp91phox, implying that NOX activity does not increase during aging. These findings show that partial cholesterol removal impairs excitation-contraction coupling and alters caveolin-3 and Cav1.1 location pattern, and that aging reduces caveolin-3 protein content and modifies the expression of other triadic proteins. We discuss the possible implications of these findings for skeletal muscle function in young and aged

  7. 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

  8. Skeletal muscle excitation-contraction coupling: who are the dancing partners?

    Science.gov (United States)

    Rebbeck, Robyn T; Karunasekara, Yamuna; Board, Philip G; Beard, Nicole A; Casarotto, Marco G; Dulhunty, Angela F

    2014-03-01

    There is an overwhelming body of work supporting the idea that excitation-contraction coupling in skeletal muscle depends on a physical interaction between the skeletal muscle isoform of the dihydropyridine receptor L-type Ca(2+) channel and the skeletal isoform of the ryanodine receptor Ca(2+) release channel. A general assumption is that this physical interaction is between "critical" residues that have been identified in the II-III loop of the dihydropyridine receptor alpha subunit and the ryanodine receptor. However, despite extensive searches, the complementary "critical" residues in the ryanodine receptor have not been identified. This raises the possibility that the coupling proceeds either through other subunits of the dihydropyridine receptor and/or other co-proteins within the large RyR1 protein complex. There have been some remarkable advances in recent years in identifying proteins in the RyR complex that impact on the coupling process, and these are considered in this review. A major candidate for a role in the coupling mechanism is the beta subunit of the dihydropyridine receptor, because specific residues in both the beta subunit and ryanodine receptor have been identified that facilitate an interaction between the two proteins and these also impact on excitation-contraction coupling. This role of beta subunit remains to be fully investigated as well as the degree to which it may complement any other direct or indirect voltage-dependent coupling interactions between the DHPR alpha II-III loop and the ryanodine receptor. Copyright © 2014. Published by Elsevier Ltd.

  9. Spatial interaction between tissue pressure and skeletal muscle perfusion during contraction.

    Science.gov (United States)

    van Donkelaar, C C; Huyghe, J M; Vankan, W J; Drost, M R

    2001-05-01

    The vascular waterfall theory attributes decreased muscle perfusion during contraction to increased intramuscular pressure (P(IM)) and concomitant increase in venous resistance. Although P(IM) is distributed during contractions, this theory does not account for heterogeneity. This study hypothesises that pressure heterogeneity could affect the interaction between P(IM) rise and perfusion. Regional tissue perfusion during submaximum (100kPa) tetanic contraction is studied, using a finite element model of perfused contracting skeletal muscle. Capillary flow in muscles with one proximal artery and vein (SIM(1)) and with an additional distal artery and vein (SIM(2)) is compared. Blood flow and pressures at rest and P(IM) during contraction ( approximately 25kPa maximally) are similar between simulations, but capillary flow and venous pressure differ. In SIM(2), venous pressure and capillary flow correspond to P(IM) distribution, whereas capillary flow in SIM(1) is less than 10% of flow in SIM(2), in the muscle half without draining vein. This difference is caused by a high central P(IM), followed by central venous pressure rise, in agreement with the waterfall theory. The high central pressure (SIM(1)), obstructs outflow from the distal veins. Distal venous pressure rises until central blood pressure is reached, although local P(IM) is low. Adding a distal vein (SIM(2)) restores the perfusion. It is concluded that regional effects contribute to the interaction between P(IM) and perfusion during contraction. Unlike stated by the vascular waterfall theory, venous pressure may locally exceed P(IM). Although this can be explained by the principles of this theory, the theory does not include this phenomenon as such.

  10. Capsiate supplementation reduces oxidative cost of contraction in exercising mouse skeletal muscle in vivo.

    Science.gov (United States)

    Yashiro, Kazuya; Tonson, Anne; Pecchi, Émilie; Vilmen, Christophe; Le Fur, Yann; Bernard, Monique; Bendahan, David; Giannesini, Benoît

    2015-01-01

    Chronic administration of capsiate is known to accelerate whole-body basal energy metabolism, but the consequences in exercising skeletal muscle remain very poorly documented. In order to clarify this issue, the effect of 2-week daily administration of either vehicle (control) or purified capsiate (at 10- or 100-mg/kg body weight) on skeletal muscle function and energetics were investigated throughout a multidisciplinary approach combining in vivo and in vitro measurements in mice. Mechanical performance and energy metabolism were assessed strictly non-invasively in contracting gastrocnemius muscle using magnetic resonance (MR) imaging and 31-phosphorus MR spectroscopy (31P-MRS). Regardless of the dose, capsiate treatments markedly disturbed basal bioenergetics in vivo including intracellular pH alkalosis and decreased phosphocreatine content. Besides, capsiate administration did affect neither mitochondrial uncoupling protein-3 gene expression nor both basal and maximal oxygen consumption in isolated saponin-permeabilized fibers, but decreased by about twofold the Km of mitochondrial respiration for ADP. During a standardized in vivo fatiguing protocol (6-min of repeated maximal isometric contractions electrically induced at a frequency of 1.7 Hz), both capsiate treatments reduced oxidative cost of contraction by 30-40%, whereas force-generating capacity and fatigability were not changed. Moreover, the rate of phosphocreatine resynthesis during the post-electrostimulation recovery period remained unaffected by capsiate. Both capsiate treatments further promoted muscle mass gain, and the higher dose also reduced body weight gain and abdominal fat content. These findings demonstrate that, in addition to its anti-obesity effect, capsiate supplementation improves oxidative metabolism in exercising muscle, which strengthen this compound as a natural compound for improving health.

  11. NO-sGC Pathway Modulates Ca2+ Release and Muscle Contraction in Zebrafish Skeletal Muscle.

    Science.gov (United States)

    Xiyuan, Zhou; Fink, Rainer H A; Mosqueira, Matias

    2017-01-01

    Vertebrate skeletal muscle contraction and relaxation is a complex process that depends on Ca 2+ ions to promote the interaction of actin and myosin. This process can be modulated by nitric oxide (NO), a gas molecule synthesized endogenously by (nitric oxide synthase) NOS isoforms. At nanomolar concentrations NO activates soluble guanylate cyclase (sGC), which in turn activates protein kinase G via conversion of GTP into cyclic GMP. Alternatively, NO post-translationally modifies proteins via S-nitrosylation of the thiol group of cysteine. However, the mechanisms of action of NO on Ca 2+ homeostasis during muscle contraction are not fully understood and we hypothesize that NO exerts its effects on Ca 2+ homeostasis in skeletal muscles mainly through negative modulation of Ca 2+ release and Ca 2+ uptake via the NO-sGC-PKG pathway. To address this, we used 5-7 days-post fecundation-larvae of zebrafish, a well-established animal model for physiological and pathophysiological muscle activity. We evaluated the response of muscle contraction and Ca 2+ transients in presence of SNAP, a NO-donor, or L-NAME, an unspecific NOS blocker in combination with specific blockers of key proteins of Ca 2+ homeostasis. We also evaluate the expression of NOS in combination with dihydropteridine receptor, ryanodine receptor and sarco/endoplasmic reticulum Ca 2+ ATPase. We concluded that endogenous NO reduced force production through negative modulation of Ca 2+ transients via the NO-sGC pathway. This effect could be reversed using an unspecific NOS blocker or sGC blocker.

  12. 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...

  13. Effect of PDE5 inhibition on the modulation of sympathetic α-adrenergic vasoconstriction in contracting skeletal muscle of young and older recreationally active humans

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin; Piil, Peter Bergmann; Egelund, Jon

    2015-01-01

    Aging is associated with an altered regulation of blood flow to contracting skeletal muscle; however, the precise mechanisms remain unclear. We recently demonstrated that inhibition of cGMP-binding phosphodiesterase 5 (PDE5) increased blood flow to contracting skeletal muscle of older but not you...

  14. Direct optical activation of skeletal muscle fibres efficiently controls muscle contraction and attenuates denervation atrophy.

    Science.gov (United States)

    Magown, Philippe; Shettar, Basavaraj; Zhang, Ying; Rafuse, Victor F

    2015-10-13

    Neural prostheses can restore meaningful function to paralysed muscles by electrically stimulating innervating motor axons, but fail when muscles are completely denervated, as seen in amyotrophic lateral sclerosis, or after a peripheral nerve or spinal cord injury. Here we show that channelrhodopsin-2 is expressed within the sarcolemma and T-tubules of skeletal muscle fibres in transgenic mice. This expression pattern allows for optical control of muscle contraction with comparable forces to nerve stimulation. Force can be controlled by varying light pulse intensity, duration or frequency. Light-stimulated muscle fibres depolarize proportionally to light intensity and duration. Denervated triceps surae muscles transcutaneously stimulated optically on a daily basis for 10 days show a significant attenuation in atrophy resulting in significantly greater contractile forces compared with chronically denervated muscles. Together, this study shows that channelrhodopsin-2/H134R can be used to restore function to permanently denervated muscles and reduce pathophysiological changes associated with denervation pathologies.

  15. Bridging the myoplasmic gap II: more recent advances in skeletal muscle excitation-contraction coupling.

    Science.gov (United States)

    Bannister, Roger A

    2016-01-01

    In skeletal muscle, excitation-contraction (EC) coupling relies on the transmission of an intermolecular signal from the voltage-sensing regions of the L-type Ca(2+) channel (Ca(V)1.1) in the plasma membrane to the channel pore of the type 1 ryanodine receptor (RyR1) nearly 10 nm away in the membrane of the sarcoplasmic reticulum (SR). Even though the roles of Ca(V)1.1 and RyR1 as voltage sensor and SR Ca(2+) release channel, respectively, have been established for nearly 25 years, the mechanism underlying communication between these two channels remains undefined. In the course of this article, I will review current viewpoints on this topic with particular emphasis on recent studies. © 2016. Published by The Company of Biologists Ltd.

  16. Inefficient functional sympatholysis is an overlooked cause of malperfusion in contracting skeletal muscle

    DEFF Research Database (Denmark)

    Saltin, Bengt; Mortensen, Stefan P

    2012-01-01

    Contracting skeletal muscle can overcome sympathetic vasoconstrictor activity (functional sympatholysis), which allows for a blood supply that matches the metabolic demand. This ability is thought to be mediated by locally released substances that modulate the effect of noradrenaline (NA) on the α...... sympatholysis and muscle blood flow are impaired compared to young men, but regular physical activity can prevent these age related impairments. In young subjects, two weeks of leg immobilization causes a reduced ability for functional sympatholysis, whereas the trained leg maintained this function. Patients...... with essential hypertension have impaired functional sympatholysis in the forearm, and reduced exercise hyperaemia in the leg, but this can be normalized by aerobic exercise training. The effect of physical activity on the local mechanisms that modulate sympathetic vasoconstriction is clear, but it remains...

  17. 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.

  18. The augmenting action of banana tree juice on skeletal muscle contraction.

    Science.gov (United States)

    Singh, Y N; Dryden, W F

    1990-01-01

    An extract obtained from juice expressed from the stem of the plantain banana tree (Musa sapientum L., var. paradisiaca) induces twitch augmentation in skeletal muscles. The mechanism of this action was investigated in the mouse hemi-diaphragm preparation. Directly evoked twitches and potassium induced (K+) contractures were both augmented by the extract. Twitch augmentation was partly dependent on extracellular Ca2+. The action on K(+)-contractures was unaffected by tetrodotoxin, but the rate of relaxation was enhanced in the absence of extracellular calcium (0[Ca2+]o). Muscle contracture induced by high concentrations of extract was also augmented in 0[Ca2+]o and in the presence of the Ca2(+)-channel blocking agent, nifedipine. The time course of the contracture was shortened in 0[Ca2+]o, but not by nifedipine. Nifedipine enhanced the augmenting effect of the extract on twitches but shortened the time-course of this action. In addition, a muscle contracture was superimposed on the twitching muscle at higher concentrations of nifedipine. Manganese, on the other hand, reduced or abolished the augmenting action of the extract. The results are consistent with an action of banana tree juice on the molecule responsible for excitation-contraction coupling in skeletal muscle, resulting in a labilization of intracellular Ca2+.

  19. Interleukin-6 receptor expression in contracting human skeletal muscle: regulating role of IL-6

    DEFF Research Database (Denmark)

    Keller, Pernille; Penkowa, Milena; Keller, Charlotte

    2005-01-01

    Contracting muscle fibers produce and release IL-6, and plasma levels of this cytokine are markedly elevated in response to physical exercise. We recently showed autocrine regulation of IL-6 in human skeletal muscle in vivo and hypothesized that this may involve up-regulation of the IL-6 receptor....... Infusion of rhIL-6 to humans had no effect on the mRNA level of the IL-6 receptor, whereas there was an increase at the protein level. IL-6 receptor mRNA increased similarly in muscle of both IL-6 KO mice and wild-type mice in response to exercise. In conclusion, exercise increases IL-6 receptor production....... Therefore, we investigated IL-6 receptor regulation in response to exercise and IL-6 infusion in humans. Furthermore, using IL-6-deficient mice, we investigated the role of IL-6 in the IL-6 receptor response to exercise. Human skeletal muscle biopsies were obtained in relation to: 3 h of bicycle exercise...

  20. Skeletal Muscle Contraction Time and Tone Decrease After 8 Weeks of Plyometric Training.

    Science.gov (United States)

    Zubac, Damir; Šimunič, Boštjan

    2017-06-01

    The aim of the study was to examine whether an improvement in jumping performance after 8 weeks of plyometric training (PT) runs in parallel with changes in lower-limb skeletal muscle contractile properties. Using noninvasive tensiomyography (TMG), we assessed contraction time (Tc) and the maximal amplitude of radial displacement (Dm) in 20 subjects (50% men; age 22.4 ± 4.7 years of age), randomly divided in PT group (N = 10; PLYO) and a control group (N = 10; CTRL). The PLYO performed 8 weeks of PT. Tensiomyography was measured in 5 leg skeletal muscles: vastus lateralis (VL), biceps femoris (BF), tibialis anterior (TA), gastrocnemius medialis (GM), and gastrocnemius lateralis (GL). Additionally, we evaluated countermovement jump (CMJ) height improvement on a ground force plate. Assessments were repeated before and after PT. After 8 weeks of PT, CMJ height increased by 12.2% in PLYO (p = 0.015), but not in CRTL. Contraction time, which is related to myosin heavy-chain type 1 (MHC-1) proportion, decreased in VL (-8.7%; p muscle tone, decreased in BF (-26.5%; p = 0.032), GM (-14.9%; p = 0.017), GL (-31.5%; p = 0.017), but not in TA (-16.8%; p = 0.113) and VL (-6.0%; p = 0.654). After PT, jumping performance increased, which was paralleled by decreased Tc and decreased muscle tone. Additionally, adaptations to contractile properties were muscle specific, which is important for future studies. It seems that adjustments were dose dependent, being higher in muscles with lower habitual load.

  1. Excitation-contraction coupling and mechano-sensitivity in denervated skeletal muscles

    Directory of Open Access Journals (Sweden)

    Fabio Francini

    2010-09-01

    Full Text Available Skeletal muscle atrophy can be defined as a wasting or decrease in muscle mass and muscle force generation owing lack of use, ageing, injury or disease. Thus, the etiology of atrophy can be different. Atrophy in denervated muscle is a consequence of two factors: 1 the complete lack of motoneuron activity inducing the deficiency of neurotransmitter release and 2 the muscles disuse. The balance of the muscular functions depends on extra- and intra-muscular signals. In the balance are involved the excitation-contraction coupling (ECC, local growth factors, Ca2+-dependent and independent intracellular signals, mechano-sensitivity and mechano-transduction that activate Ca2+-dependent signaling proteins and cytoskeleton- nucleus pathways to the nucleus, that regulate the gene expression. Moreover, retrograde signal from intracellular compartments and cytoskeleton to the sarcolemma are additional factors that regulate the muscle function. Proteolytic systems that operate in atrophic muscles progressively reduce the muscle protein content and so the sarcolemma, ECC and the force generation. In this review we will focus on the more relevant changes of the sarcolemma, excitation-contraction coupling, ECC and mechano-transduction evaluated by electrophysiological methods and observed from early- to long-term denervated skeletal muscles. This review put in particular evidence that long-term denervated muscle maintain a sub-population of fibers with ECC and contractile machinery able to be activated, albeit in lesser amounts, by electrical and mechanical stimulation. Accordingly, this provides a potential molecular explanation of the muscle recovery that occurs in response to rehabilitation strategy as transcutaneous electrical stimulation and passive stretching of denervated muscles, which wre developed as a result of empirical clinical observations.

  2. Sucrose nonfermenting AMPK-related kinase (SNARK) mediates contraction-stimulated glucose transport in mouse skeletal muscle

    DEFF Research Database (Denmark)

    Koh, Ho-Jin; Toyoda, Taro; Fujii, Nobuharu

    2010-01-01

    The signaling mechanisms that mediate the important effects of contraction to increase glucose transport in skeletal muscle are not well understood, but are known to occur through an insulin-independent mechanism. Muscle-specific knockout of LKB1, an upstream kinase for AMPK and AMPK-related prot...

  3. Naftopidil inhibits 5-hydroxytryptamine-induced bladder contraction in rats.

    Science.gov (United States)

    Sakai, Takumi; Kasahara, Ken-ichi; Tomita, Ken-ichi; Ikegaki, Ichiro; Kuriyama, Hiroshi

    2013-01-30

    Naftopidil is an α(1D) and α(1A) subtype-selective α(1)-adrenoceptor antagonist that has been used to treat lower urinary tract symptoms of benign prostatic hyperplasia. In this study, we investigated the effects of naftopidil on 5-hydroxytryptamine (5-HT)-induced rat bladder contraction (10(-8)-10(-4) M). Naftopidil (0.3, 1, and 3 μM) inhibited 5-HT-induced bladder contraction in a concentration-dependent manner. On the other hand, other α(1)-adrenoceptor antagonists, tamsulosin, silodosin or prazosin, did not inhibit 5-HT-induced bladder contraction. The 5-HT-induced bladder contraction was inhibited by both ketanserin and 4-(4-fluoronaphthalen-1-yl)-6-propan-2-ylpyrimidin-2-amine (RS127445), serotonin 5-HT(2A) and 5-HT(2B) receptor antagonists, respectively. In addition, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) and α-methyl-5-HT, 5-HT(2A) and 5-HT(2) receptor agonists, respectively, induced bladder contraction. The 5-HT-induced bladder contraction was not inhibited by N-[2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl]-N-pyridin-2-yl-cyclohexanecarboxamide (WAY-100635), [1-[2[(methylsulfonyl)amino]ethyl]-4-piperidinyl]methyl-1-methyl-1H-indole-3-carboxylate (GR113808) or (R)-3-[2-[2-(4-methylpiperidin-1-yl)ethyl]pyrrolidine-1-sulphonyl]phenol (SB269970), 5-HT(1A), 5-HT(4) and 5-HT(7) receptor antagonists, respectively. Naftopidil inhibited both the 5-HT(2A) and 5-HT(2) receptor agonists-induced bladder contractions. Naftopidil binds to the human 5-HT(2A) and 5-HT(2B) receptors with pKi values of 6.55 and 7.82, respectively. These results suggest that naftopidil inhibits 5-HT-induced bladder contraction via blockade of the 5-HT(2A) and 5-HT(2B) receptors in rats. Furthermore, 5-HT-induced bladder contraction was enhanced in bladder strips obtained from bladder outlet obstructed rats, with this contraction inhibited by naftopidil. The beneficial effects of naftopidil on storage symptoms such as urinary frequency and nocturia in patients with benign

  4. Knockout of the predominant conventional PKC isoform, PKCalpha, in mouse skeletal muscle does not affect contraction-stimulated glucose uptake

    DEFF Research Database (Denmark)

    Jensen, Thomas E; Maarbjerg, Stine J; Rose, Adam J

    2009-01-01

    Conventional (c) protein kinase C (PKC) activity has been shown to increase with skeletal muscle contraction, and numerous studies using primarily pharmacological inhibitors have implicated cPKCs in contraction-stimulated glucose uptake. Here, to confirm that cPKC activity is required for contrac...... working on other parts of contraction-induced signaling or the remaining cPKC isoforms are sufficient for stimulating glucose uptake during contractions.......Conventional (c) protein kinase C (PKC) activity has been shown to increase with skeletal muscle contraction, and numerous studies using primarily pharmacological inhibitors have implicated cPKCs in contraction-stimulated glucose uptake. Here, to confirm that cPKC activity is required...... for contraction-stimulated glucose uptake in mouse muscles, contraction-stimulated glucose uptake ex vivo was first evaluated in the presence of three commonly used cPKC inhibitors (calphostin C, Gö-6976, and Gö-6983) in incubated mouse soleus and extensor digitorum longus (EDL) muscles. All potently inhibited...

  5. Caloric restriction induces energy-sparing alterations in skeletal muscle contraction, fiber composition and local thyroid hormone metabolism that persist during catch-up fat upon refeeding

    Directory of Open Access Journals (Sweden)

    Paula Bresciani M. De Andrade

    2015-09-01

    Full Text Available Weight regain after caloric restriction results in accelerated fat storage in adipose tissue. This catch-up fat phenomenon is postulated to result partly from suppressed skeletal muscle thermogenesis, but the underlying mechanisms are elusive. We investigated whether the reduced rate of skeletal muscle contraction-relaxation cycle that occurs after caloric restriction persists during weight recovery and could contribute to catch-up fat. Using a rat model of semistarvation-refeeding, in which fat recovery is driven by suppressed thermogenesis, we show that contraction and relaxation of leg muscles are slower after both semistarvation and refeeding. These effects are associated with (i higher expression of muscle deiodinase type 3 (DIO3 which inactivates tri-iodothyronine (T3, and lower expression of T3-activating enzyme, deiodinase type 2 (DIO2, (ii slower net formation of T3 from its T4 precursor in muscles, and (iii accumulation of slow fibers at the expense of fast fibers. These semistarvation-induced changes persisted during recovery and correlated with impaired expression of transcription factors involved in slow-twitch muscle development.We conclude that diminished muscle thermogenesis following caloric restriction results from reduced muscle T3 levels, alteration in muscle-specific transcription factors, and fast-to-slow fiber shift causing slower contractility. Energy-sparing effects persist during weight recovery and likely contribute to catch-up fat.

  6. Caloric restriction induces energy-sparing alterations in skeletal muscle contraction, fiber composition and local thyroid hormone metabolism that persist during catch-up fat upon refeeding.

    Science.gov (United States)

    De Andrade, Paula B M; Neff, Laurence A; Strosova, Miriam K; Arsenijevic, Denis; Patthey-Vuadens, Ophélie; Scapozza, Leonardo; Montani, Jean-Pierre; Ruegg, Urs T; Dulloo, Abdul G; Dorchies, Olivier M

    2015-01-01

    Weight regain after caloric restriction results in accelerated fat storage in adipose tissue. This catch-up fat phenomenon is postulated to result partly from suppressed skeletal muscle thermogenesis, but the underlying mechanisms are elusive. We investigated whether the reduced rate of skeletal muscle contraction-relaxation cycle that occurs after caloric restriction persists during weight recovery and could contribute to catch-up fat. Using a rat model of semistarvation-refeeding, in which fat recovery is driven by suppressed thermogenesis, we show that contraction and relaxation of leg muscles are slower after both semistarvation and refeeding. These effects are associated with (i) higher expression of muscle deiodinase type 3 (DIO3), which inactivates tri-iodothyronine (T3), and lower expression of T3-activating enzyme, deiodinase type 2 (DIO2), (ii) slower net formation of T3 from its T4 precursor in muscles, and (iii) accumulation of slow fibers at the expense of fast fibers. These semistarvation-induced changes persisted during recovery and correlated with impaired expression of transcription factors involved in slow-twitch muscle development. We conclude that diminished muscle thermogenesis following caloric restriction results from reduced muscle T3 levels, alteration in muscle-specific transcription factors, and fast-to-slow fiber shift causing slower contractility. These energy-sparing effects persist during weight recovery and contribute to catch-up fat.

  7. 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

  8. The ATP required for potentiation of skeletal muscle contraction is released via pannexin hemichannels.

    Science.gov (United States)

    Riquelme, Manuel A; Cea, Luis A; Vega, José L; Boric, Mauricio P; Monyer, Hannah; Bennett, Michael V L; Frank, Marina; Willecke, Klaus; Sáez, Juan C

    2013-12-01

    During repetitive stimulation of skeletal muscle, extracellular ATP levels raise, activating purinergic receptors, increasing Ca2+ influx, and enhancing contractile force, a response called potentiation. We found that ATP appears to be released through pannexin1 hemichannels (Panx1 HCs). Immunocytochemical analyses and function were consistent with pannexin1 localization to T-tubules intercalated with dihydropyridine and ryanodine receptors in slow (soleus) and fast (extensor digitorum longus, EDL) muscles. Isolated myofibers took up ethidium (Etd+) and released small molecules (as ATP) during electrical stimulation. Consistent with two glucose uptake pathways, induced uptake of 2-NBDG, a fluorescent glucose derivative, was decreased by inhibition of HCs or glucose transporter (GLUT4), and blocked by dual blockade. Adult skeletal muscles apparently do not express connexins, making it unlikely that connexin hemichannels contribute to the uptake and release of small molecules. ATP release, Etd+ uptake, and potentiation induced by repetitive electrical stimulation were blocked by HC blockers and did not occur in muscles of pannexin1 knockout mice. MRS2179, a P2Y1R blocker, prevented potentiation in EDL, but not soleus muscles, suggesting that in fast muscles ATP activates P2Y1 but not P2X receptors. Phosphorylation on Ser and Thr residues of pannexin1 was increased during potentiation, possibly mediating HC opening. Opening of Panx1 HCs during repetitive activation allows efflux of ATP, influx of glucose and possibly Ca2+ too, which are required for potentiation of contraction. This article is part of the Special Issue Section entitled 'Current Pharmacology of Gap Junction Channels and Hemichannels'. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. 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...

  10. 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.

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

    Science.gov (United States)

    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.

  12. Effects of drugs and ionic variations on contractions of rat smooth ...

    African Journals Online (AJOL)

    The result of this suggests that as membrane depolarisation increases contraction in Rat Vas Deferens smooth muscle declined, while Verapamil and Nifedipine were more sensitive in blocking K+ than Ach and NA induced contractions. Keywords: Smooth muscle, Ileum, Stomach strip, Vas deferens, Contractions, Rat.

  13. Excitation contraction uncoupling by high intracellular [Ca2+] in frog skeletal muscle: a voltage clamp study.

    Science.gov (United States)

    Olivera, J Fernando; Pizarro, Gonzalo

    2016-10-01

    Raising the intracellular [Ca 2+ ] ([Ca 2+ ] i ) was previously found to produce uncoupling between the electrical depolarization of the transverse tubules and contraction in skinned muscle fibers. Here we study the effect of elevated [Ca 2+ ] i in voltage clamped cut fibers of frog skeletal muscle to establish how the charge movement, a measure of the activation of the dihydropyridine receptors (DHPR)-voltage sensors, and Ca 2+ release, a consequence of the opening of the ryanodine receptor (RyR)-release channels, were affected. [Ca 2+ ] i was raised by various procedures (pharmacological release from the sarcoplasmic reticulum, application of high [Ca 2+ ] i intracellular solution, permeabilization of the plasma membrane by a Ca 2+ ionophore) all of which produced impairment of excitation-contraction coupling. The charge movement was reduced from 20.2 ± 1.24 to 9.9 ± 0.94 nC/μF meanwhile the Ca 2+ release flux was reduced from 13.5 + 0.7 to 2.2 ± 0.3 μM/ms (n = 33). This suggests that a significant fraction of the DHPRs that remained functional, could not activate RyRs, and were therefore presumably disconnected. These results are broadly consistent with the original reports in skinned fibers. Uncoupling was prevented by the addition to the intracellular solution of the protease inhibitor leupeptin. In approximately 40 % of the uncoupled cells we observed that the [Ca 2+ ] i transient continued to rise after the voltage clamp pulse was turned off. This loss of control by membrane voltage suggests that the uncoupled release channels might have another mechanism of activation, likely by Ca 2+ .

  14. Distinct Skeletal Muscle Gene Regulation from Active Contraction, Passive Vibration, and Whole Body Heat Stress in Humans.

    Science.gov (United States)

    Petrie, Michael A; Kimball, Amy L; McHenry, Colleen L; Suneja, Manish; Yen, Chu-Ling; Sharma, Arpit; Shields, Richard K

    2016-01-01

    Skeletal muscle exercise regulates several important metabolic genes in humans. We know little about the effects of environmental stress (heat) and mechanical stress (vibration) on skeletal muscle. Passive mechanical stress or systemic heat stress are often used in combination with many active exercise programs. We designed a method to deliver a vibration stress and systemic heat stress to compare the effects with active skeletal muscle contraction. The purpose of this study is to examine whether active mechanical stress (muscle contraction), passive mechanical stress (vibration), or systemic whole body heat stress regulates key gene signatures associated with muscle metabolism, hypertrophy/atrophy, and inflammation/repair. Eleven subjects, six able-bodied and five with chronic spinal cord injury (SCI) participated in the study. The six able-bodied subjects sat in a heat stress chamber for 30 minutes. Five subjects with SCI received a single dose of limb-segment vibration or a dose of repetitive electrically induced muscle contractions. Three hours after the completion of each stress, we performed a muscle biopsy (vastus lateralis or soleus) to analyze mRNA gene expression. We discovered repetitive active muscle contractions up regulated metabolic transcription factors NR4A3 (12.45 fold), PGC-1α (5.46 fold), and ABRA (5.98 fold); and repressed MSTN (0.56 fold). Heat stress repressed PGC-1α (0.74 fold change; p muscle contraction. Vibration induced FOXK2 (p muscle contractions. Understanding these responses may assist in developing regenerative rehabilitation interventions to improve muscle cell development, growth, and repair.

  15. 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...

  16. ALUMINUM CHLORIDE EFFECT ON Ca2+,Mg(2+)-ATPase ACTIVITY AND DYNAMIC PARAMETERS OF SKELETAL MUSCLE CONTRACTION.

    Science.gov (United States)

    Nozdrenko, D M; Abramchuk, O M; Soroca, V M; Miroshnichenko, N S

    2015-01-01

    We studied enzymatic activity and measured strain-gauge contraction properties of the frog Rana temporaria m. tibialis anterior muscle fascicles during the action of aluminum chloride solution. It was shown that AlCl3 solutions did not affect the dynamic properties of skeletal muscle preparation in concentrations less than 10(-4) M Increasing the concentration of AlCl3 to 10(-2) M induce complete inhibition of muscle contraction. A linear correlation between decrease in Ca2+,Mg(2+)-ATPase activity of sarcoplasmic reticulum and the investigated concentrations range of aluminum chloride was observed. The reduction in the dynamic contraction performance and the decrease Ca2+,Mg(2+)-ATPase activity of the sarcoplasmic reticulum under the effect of the investigated AlCl3 solution were minimal in pre-tetanus period of contraction.

  17. Aluminum chloride effect on Ca(2+,Mg(2+-ATPase activity and dynamic parameters of skeletal muscle contraction

    Directory of Open Access Journals (Sweden)

    D. M. Nozdrenko

    2015-10-01

    Full Text Available We studied enzymatic activity and measured strain-gauge contraction properties of the frog Rana temporaria m. tibialis anterior muscle fascicles during the action of aluminum chloride solution. It was shown that AlCl3 solutions did not affect the dynamic properties of skeletal muscle preparation in concentrations less than 10-4 M. Increasing the concentration of AlCl3 to 10-2 M induce complete inhibition of muscle contraction. A linear correlation between decrease in Ca2+,Mg2+-ATPase activity of sarcoplasmic reticulum and the investigated concentrations range of aluminum chloride was observed. The reduction in the dynamic contraction performance and the decrease Ca2+,Mg2+-ATPase activity of the sarcoplasmic reticulum under the effect of the investigated AlCl3 solution were minimal in pre-tetanus period of contraction.

  18. 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.

  19. Role of dystroglycan in limiting contraction-induced injury to the sarcomeric cytoskeleton of mature skeletal muscle.

    Science.gov (United States)

    Rader, Erik P; Turk, Rolf; Willer, Tobias; Beltrán, Daniel; Inamori, Kei-Ichiro; Peterson, Taylor A; Engle, Jeffrey; Prouty, Sally; Matsumura, Kiichiro; Saito, Fumiaki; Anderson, Mary E; Campbell, Kevin P

    2016-09-27

    Dystroglycan (DG) is a highly expressed extracellular matrix receptor that is linked to the cytoskeleton in skeletal muscle. DG is critical for the function of skeletal muscle, and muscle with primary defects in the expression and/or function of DG throughout development has many pathological features and a severe muscular dystrophy phenotype. In addition, reduction in DG at the sarcolemma is a common feature in muscle biopsies from patients with various types of muscular dystrophy. However, the consequence of disrupting DG in mature muscle is not known. Here, we investigated muscles of transgenic mice several months after genetic knockdown of DG at maturity. In our study, an increase in susceptibility to contraction-induced injury was the first pathological feature observed after the levels of DG at the sarcolemma were reduced. The contraction-induced injury was not accompanied by increased necrosis, excitation-contraction uncoupling, or fragility of the sarcolemma. Rather, disruption of the sarcomeric cytoskeleton was evident as reduced passive tension and decreased titin immunostaining. These results reveal a role for DG in maintaining the stability of the sarcomeric cytoskeleton during contraction and provide mechanistic insight into the cause of the reduction in strength that occurs in muscular dystrophy after lengthening contractions.

  20. Sex and nitric oxide bioavailability interact to modulate interstitial PO2 in healthy rat skeletal muscle.

    Science.gov (United States)

    Craig, Jesse C; Colburn, Trenton D; Hirai, Daniel M; Schettler, Michael J; Musch, Timothy I; Poole, David C

    2018-01-25

    Pre-menopausal women express reduced blood pressure and risk of cardiovascular disease relative to age-matched men. This purportedly relates to elevated estrogen levels increasing nitric oxide synthase (NOS) activity and NO-mediated vasorelaxation. We tested the hypotheses that female rat skeletal muscle would: 1) evince higher O 2 delivery-to-utilization ratio (Q̇O 2 /V̇O 2 ) during contractions; and 2) express greater modulation of Q̇O 2 /V̇O 2 with changes to NO bioavailability, compared to males. The spinotrapezius muscle of Sprague-Dawley rats (females (♀)=8, males (♂)=8) was surgically exposed and electrically-stimulated (180s, 1Hz, 6V). OxyphorG4 was injected into the muscle and phosphorescence quenching employed to determine the temporal profile of interstitial PO 2 (PO 2is , determined by Q̇O 2 /V̇O 2 ). This was performed under three conditions: control (CON), 300 µM sodium nitroprusside (SNP; NO donor), and 1.5 mM L-arginine methyl ester (L-NAME; NOS blockade) superfusion. No sex differences were found for the PO 2is kinetics parameters in CON or L-NAME (p>0.05), but females elicited a lower baseline following SNP (♂:42{plus minus}3 vs ♀:36{plus minus}2 mmHg, p0.05). The total NO effect (SNP minus L-NAME) on PO 2is was not different between sexes. However, the spread across both conditions was shifted to a lower absolute range for females (reduced SNP baseline and greater reduction following L-NAME). These data support that females have a greater reliance on basal NO bioavailability and males have greater responsiveness to exogenous NO and less responsiveness to reduced endogenous NO.

  1. 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.

  2. Cytosolic calcium transients are a determinant of contraction-induced HSP72 transcription in single skeletal muscle fibers.

    Science.gov (United States)

    Stary, Creed M; Hogan, Michael C

    2016-05-15

    The intrinsic activating factors that induce transcription of heat shock protein 72 (HSP72) in skeletal muscle following exercise remain unclear. We hypothesized that the cytosolic Ca(2+) transient that occurs with depolarization is a determinant. We utilized intact, single skeletal muscle fibers from Xenopus laevis to test the role of the cytosolic Ca(2+) transient and several other exercise-related factors (fatigue, hypoxia, AMP kinase, and cross-bridge cycling) on the activation of HSP72 transcription. HSP72 and HSP60 mRNA levels were assessed with real-time quantitative PCR; cytosolic Ca(2+) concentration ([Ca(2+)]cyt) was assessed with fura-2. Both fatiguing and nonfatiguing contractions resulted in a significant increase in HSP72 mRNA. As expected, peak [Ca(2+)]cyt remained tightly coupled with peak developed tension in contracting fibers. Pretreatment with N-benzyl-p-toluene sulfonamide (BTS) resulted in depressed peak developed tension with stimulation, while peak [Ca(2+)]cyt remained largely unchanged from control values. Despite excitation-contraction uncoupling, BTS-treated fibers displayed a significant increase in HSP72 mRNA. Treatment of fibers with hypoxia (Po2: skeletal muscle depolarization provides a sufficient activating stimulus for HSP72 transcription. Metabolic or mechanical factors associated with fatigue development and cross-bridge cycling likely play a more limited role. Copyright © 2016 the American Physiological Society.

  3. Rem uncouples excitation–contraction coupling in adult skeletal muscle fibers

    Science.gov (United States)

    Beqollari, Donald; Romberg, Christin F.; Filipova, Dilyana; Meza, Ulises; Papadopoulos, Symeon

    2015-01-01

    In skeletal muscle, excitation–contraction (EC) coupling requires depolarization-induced conformational rearrangements in L-type Ca2+ channel (CaV1.1) to be communicated to the type 1 ryanodine-sensitive Ca2+ release channel (RYR1) of the sarcoplasmic reticulum (SR) via transient protein–protein interactions. Although the molecular mechanism that underlies conformational coupling between CaV1.1 and RYR1 has been investigated intensely for more than 25 years, the question of whether such signaling occurs via a direct interaction between the principal, voltage-sensing α1S subunit of CaV1.1 and RYR1 or through an intermediary protein persists. A substantial body of evidence supports the idea that the auxiliary β1a subunit of CaV1.1 is a conduit for this intermolecular communication. However, a direct role for β1a has been difficult to test because β1a serves two other functions that are prerequisite for conformational coupling between CaV1.1 and RYR1. Specifically, β1a promotes efficient membrane expression of CaV1.1 and facilitates the tetradic ultrastructural arrangement of CaV1.1 channels within plasma membrane–SR junctions. In this paper, we demonstrate that overexpression of the RGK protein Rem, an established β subunit–interacting protein, in adult mouse flexor digitorum brevis fibers markedly reduces voltage-induced myoplasmic Ca2+ transients without greatly affecting CaV1.1 targeting, intramembrane gating charge movement, or releasable SR Ca2+ store content. In contrast, a β1a-binding–deficient Rem triple mutant (R200A/L227A/H229A) has little effect on myoplasmic Ca2+ release in response to membrane depolarization. Thus, Rem effectively uncouples the voltage sensors of CaV1.1 from RYR1-mediated SR Ca2+ release via its ability to interact with β1a. Our findings reveal Rem-expressing adult muscle as an experimental system that may prove useful in the definition of the precise role of the β1a subunit in skeletal-type EC coupling. PMID:26078055

  4. 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

  5. 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

  6. Extracellular adenosine initiates rapid arteriolar vasodilation induced by a single skeletal muscle contraction in hamster cremaster muscle.

    Science.gov (United States)

    Ross, G A; Mihok, M L; Murrant, C L

    2013-05-01

    Recent studies suggest that adenosine (ADO) can be produced extracellularly in response to skeletal muscle contraction. We tested the hypothesis that a single muscle contraction produces extracellular ADO rapidly enough and in physiologically relevant concentrations to be able to contribute to the rapid vasodilation that occurs at the onset of muscle contraction. We stimulated four to five skeletal muscle fibres in the anaesthetized hamster cremaster preparation in situ and measured the change in diameter of arterioles at a site of overlap with the stimulated muscle fibres before and after a single contraction (stimulus frequencies: 4, 20 and 60 Hz; 250 ms train duration). Muscle fibres were stimulated in the absence and presence of non-specific ADO membrane receptor antagonists 8-phenyltheophylline (8-PT, 10(-6) M) or xanthine amine congener (XAC, 10(-6) M) or an inhibitor of an extracellular source of ADO, ecto-5'-nucleotidase inhibitor α,β-methylene adenosine 5'-diphosphate (AMPCP, 10(-5) M). We observed that the dilatory event at 4 s following a single contraction was significantly inhibited at all stimulus frequencies by an average of 63.9 ± 2.6% by 8-PT. The 20-s dilatory event that occurred at 20 and 60 Hz was significantly inhibited by 53.6 ± 2.6 and 73.8 ± 2.3% by 8-PT and XAC respectively. Further, both the 4- and 20-s dilatory events were significantly inhibited by AMPCP by 78.6 ± 6.6 and 67.1 ± 1.5%, respectively, at each stimulus frequency tested. Our data show that ADO is produced extracellularly during a single muscle contraction and that it is produced rapidly enough and in physiologically relevant concentrations to contribute to the rapid vasodilation in response to muscle contraction. © 2013 The Authors Acta Physiologica © 2013 Scandinavian Physiological Society.

  7. Favorable effect of moderate dose caffeine on the skeletal system in ovariectomized rats.

    Science.gov (United States)

    Folwarczna, Joanna; Pytlik, Maria; Zych, Maria; Cegieła, Urszula; Kaczmarczyk-Sedlak, Ilona; Nowińska, Barbara; Sliwiński, Leszek

    2013-10-01

    Caffeine, a methylxanthine present in coffee, has been postulated to be responsible for an increased risk of osteoporosis in coffee drinkers; however, the data are inconsistent. The aim of the present study was to investigate the effects of a moderate dose of caffeine on the skeletal system of rats with normal and decreased estrogen level (developing osteoporosis due to estrogen deficiency). The experiments were carried out on mature nonovariectomized and ovariectomized Wistar rats, divided into control rats and rats receiving caffeine once daily, 20 mg/kg p.o., for 4 wk. Serum bone turnover markers, bone mass, mass of bone mineral, calcium and phosphorus content, histomorphometric parameters, and bone mechanical properties were examined. Caffeine favorably affected the skeletal system of ovariectomized rats, slightly inhibiting the development of bone changes induced by estrogen deficiency (increasing bone mineralization, and improving the strength and structure of cancellous bone). Moreover, it favorably affected mechanical properties of compact bone. There were no significant effects of caffeine in rats with normal estrogen levels. In conclusion, results of the present study indicate that low-to-moderate caffeine intake may exert some beneficial effects on the skeletal system of mature organisms. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    DEFF Research Database (Denmark)

    Alsted, Thomas Junker; Ploug, Thorkil; Prats Gavalda, Clara

    2013-01-01

    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-KO mice. Measurements of IMTG are complicated by the presence of adipocytes located between the muscle fibers....... To circumvent the problem with this contamination we analyzed 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...

  9. 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)

  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. Age-related functional changes and susceptibility to eccentric contraction-induced damage in skeletal muscle cell.

    Science.gov (United States)

    Choi, Seung-Jun

    2016-09-01

    Depending upon external loading conditions, skeletal muscles can either shorten, lengthen, or remain at a fixed length as they produce force. Fixed-end or isometric contractions stabilize joints and allow muscles to act as active struts during locomotion. Active muscles dissipate energy when they are lengthened by an external force that exceeds their current force producing capacity. These unaccustomed eccentric activities often lead to muscle weakness, soreness, and inflammation. During aging, the ability to produce force under these conditions is reduced and appears to be due to not only reductions in muscle mass but also to alterations in the basic mechanisms of contraction. These alterations include impairments in the excitation-contraction process, and the action of the cross-bridges. Also, it is well known that age-related skeletal muscle atrophy is characterized by a preferential atrophy of fast fibers, and increased susceptibility to fast muscle fiber when aged muscles are exposed to eccentric contraction followed by the impaired recovery process has been reported. Taken together, the selective loss of fast muscle fiber in aged muscle could be affected by eccentric-induced muscle damage, which has significant implication to identify the etiology of the age-related functional changes. Therefore, in this review the alteration of age-related muscle function and its impact to/of eccentric induced muscle damage and recovery will be addressed in detail.

  12. Age-related functional changes and susceptibility to eccentric contraction-induced damage in skeletal muscle cell

    Directory of Open Access Journals (Sweden)

    Seung-Jun Choi

    2016-09-01

    Full Text Available Depending upon external loading conditions, skeletal muscles can either shorten, lengthen, or remain at a fixed length as they produce force. Fixed-end or isometric contractions stabilize joints and allow muscles to act as active struts during locomotion. Active muscles dissipate energy when they are lengthened by an external force that exceeds their current force producing capacity. These unaccustomed eccentric activities often lead to muscle weakness, soreness, and inflammation. During aging, the ability to produce force under these conditions is reduced and appears to be due to not only reductions in muscle mass but also to alterations in the basic mechanisms of contraction. These alterations include impairments in the excitation–contraction process, and the action of the cross-bridges. Also, it is well known that age-related skeletal muscle atrophy is characterized by a preferential atrophy of fast fibers, and increased susceptibility to fast muscle fiber when aged muscles are exposed to eccentric contraction followed by the impaired recovery process has been reported. Taken together, the selective loss of fast muscle fiber in aged muscle could be affected by eccentric-induced muscle damage, which has significant implication to identify the etiology of the age-related functional changes. Therefore, in this review the alteration of age-related muscle function and its impact to/of eccentric induced muscle damage and recovery will be addressed in detail.

  13. 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.

  14. 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

  15. [Post-traumatic reconnection of the cervical spinal cord with skeletal striated muscles. Study in adult rats and marmosets].

    Science.gov (United States)

    Horvat, J C; Affane-Boulaid, F; Baillet-Derbin, C; Davarpanah, Y; Destombes, J; Duchossoy, Y; Emery, E; Kassar-Duchossoy, L; Mira, J C; Moissonnier, P; Pécot-Dechavassine, M; Reviron, T; Rhrich-Haddout, F; Tadié, M; Ye, J H

    1997-01-01

    In an attempt at repairing the injured spinal cord of adult mammals (rat, dog and marmoset) and its damaged muscular connections, we are currently using: 1) peripheral nerve autografts (PNG), containing Schwann cells, to trigger and direct axonal regrowth from host and/or transplanted motoneurons towards denervated muscular targets; 2) foetal spinal cord transplants to replace lost neurons. In adult rats and marmosets, a PNG bridge was used to joint the injured cervical spinal cord to a denervated skeletal muscle (longissimus atlantis [rat] or biceps brachii [rat and marmoset]). The spinal lesion was obtained by the implantation procedure of the PNG. After a post-operative delay ranging from 2 to 22 months, the animals were checked electrophysiologically for functional muscular reconnection and processed for a morphological study including retrograde axonal tracing (HRP, Fast Blue, True Blue), histochemistry (AChE, ATPase), immunocytochemistry (ChAT) and EM. It was thus demonstrated that host motoneurons of the cervical enlargement could extend axons all the way through the PNG bridge as: a) in anaesthetized animals, contraction of the reconnected muscle could be obtained by electrical stimulation of the grafted nerve; b) the retrograde axonal tracing studies indicated that a great number of host cervical neurons extended axons into the PNG bridge up to the muscle; c) many of them were assumed to be motoneurons (double labelling with True Blue and an antibody against ChAT); and even alpha-motoneurons (type C axosomatic synapses in HRP labelled neurons seen in EM in the rat); d) numerous ectopic endplates were seen around the intramuscular tip of the PNG. In larger (cavitation) spinal lesions (rat), foetal motoneurons contained in E14 spinal cord transplants could similarly grow axons through PNG bridges up to the reconnected muscle. Taking all these data into account, it can be concluded that neural transplants are interesting tools for evaluating both the

  16. Cytoskeletal Tropomyosin Tm5NM1 Is Required for Normal Excitation–Contraction Coupling in Skeletal Muscle

    Science.gov (United States)

    Vlahovich, Nicole; Kee, Anthony J.; Van der Poel, Chris; Kettle, Emma; Hernandez-Deviez, Delia; Lucas, Christine; Lynch, Gordon S.; Parton, Robert G.; Gunning, Peter W.

    2009-01-01

    The functional diversity of the actin microfilaments relies in part on the actin binding protein tropomyosin (Tm). The muscle-specific Tms regulate actin-myosin interactions and hence contraction. However, there is less known about the roles of the numerous cytoskeletal isoforms. We have shown previously that a cytoskeletal Tm, Tm5NM1, defines a Z-line adjacent cytoskeleton in skeletal muscle. Recently, we identified a second cytoskeletal Tm in this region, Tm4. Here we show that Tm4 and Tm5NM1 define separate actin filaments; the former associated with the terminal sarcoplasmic reticulum (SR) and other tubulovesicular structures. In skeletal muscles of Tm5NM1 knockout (KO) mice, Tm4 localization was unchanged, demonstrating the specificity of the membrane association. Tm5NM1 KO muscles exhibit potentiation of T-system depolarization and decreased force rundown with repeated T-tubule depolarizations consistent with altered T-tubule function. These results indicate that a Tm5NM1-defined actin cytoskeleton is required for the normal excitation–contraction coupling in skeletal muscle. PMID:19005216

  17. Cytoskeletal tropomyosin Tm5NM1 is required for normal excitation-contraction coupling in skeletal muscle.

    Science.gov (United States)

    Vlahovich, Nicole; Kee, Anthony J; Van der Poel, Chris; Kettle, Emma; Hernandez-Deviez, Delia; Lucas, Christine; Lynch, Gordon S; Parton, Robert G; Gunning, Peter W; Hardeman, Edna C

    2009-01-01

    The functional diversity of the actin microfilaments relies in part on the actin binding protein tropomyosin (Tm). The muscle-specific Tms regulate actin-myosin interactions and hence contraction. However, there is less known about the roles of the numerous cytoskeletal isoforms. We have shown previously that a cytoskeletal Tm, Tm5NM1, defines a Z-line adjacent cytoskeleton in skeletal muscle. Recently, we identified a second cytoskeletal Tm in this region, Tm4. Here we show that Tm4 and Tm5NM1 define separate actin filaments; the former associated with the terminal sarcoplasmic reticulum (SR) and other tubulovesicular structures. In skeletal muscles of Tm5NM1 knockout (KO) mice, Tm4 localization was unchanged, demonstrating the specificity of the membrane association. Tm5NM1 KO muscles exhibit potentiation of T-system depolarization and decreased force rundown with repeated T-tubule depolarizations consistent with altered T-tubule function. These results indicate that a Tm5NM1-defined actin cytoskeleton is required for the normal excitation-contraction coupling in skeletal muscle.

  18. Skeletal growth and long-term bone turnover after enterocystoplasty in a chronic rat model

    DEFF Research Database (Denmark)

    Gerharz, E.W.; Gasser, J.A.; Mosekilde, Li.

    2003-01-01

    OBJECTIVE: To investigate skeletal growth and bone metabolism in a chronic animal model of urinary diversion.MATERIALS AND METHODS: Young male Wistar rats (120) were allocated randomly to four groups undergoing: ileocystoplasty, ileocystoplasty and resection of the ileocaecal segment, colocystopl......OBJECTIVE: To investigate skeletal growth and bone metabolism in a chronic animal model of urinary diversion.MATERIALS AND METHODS: Young male Wistar rats (120) were allocated randomly to four groups undergoing: ileocystoplasty, ileocystoplasty and resection of the ileocaecal segment......, colocystoplasty, and controls. All animals received antibiotics for 1 week after surgery; half of each group remained on oral antibiotics. Bone-related biochemistry was measured in serum and urine. Dual-energy X-ray absorptiometry and peripheral quantitative computed tomography (pQCT) were used to determine bone...... no differences in bone length and volume. Loss of bone mass was almost exclusively in rats with ileocystoplasty and resection of the ileocaecal segment (-37.5%, pQCT, P

  19. Phosphoinositides in Ca(2+) signaling and excitation-contraction coupling in skeletal muscle: an old player and newcomers.

    Science.gov (United States)

    Csernoch, Laszlo; Jacquemond, Vincent

    2015-12-01

    Since the postulate, 30 years ago, that phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P 2) as the precursor of inositol 1,4,5-trisphosphate (Ins(1,4,5)P 3) would be critical for skeletal muscle excitation-contraction (EC) coupling, the issue of whether phosphoinositides (PtdInsPs) may have something to do with Ca(2+) signaling in muscle raised limited interest, if any. In recent years however, the PtdInsP world has expanded considerably with new functions for PtdIns(4,5)P 2 but also with functions for the other members of the PtdInsP family. In this context, the discovery that genetic deficiency in a PtdInsP phosphatase has dramatic consequences on Ca(2+) homeostasis in skeletal muscle came unanticipated and opened up new perspectives in regards to how PtdInsPs modulate muscle Ca(2+) signaling under normal and disease conditions. This review intends to make an update of the established, the questioned, and the unknown regarding the role of PtdInsPs in skeletal muscle Ca(2+) homeostasis and EC coupling, with very specific emphasis given to Ca(2+) signals in differentiated skeletal muscle fibers.

  20. A small-molecule benzimidazole derivative that potently activates AMPK to increase glucose transport in skeletal muscle: comparison with effects of contraction and other AMPK activators.

    Science.gov (United States)

    Lai, Yu-Chiang; Kviklyte, Samanta; Vertommen, Didier; Lantier, Louise; Foretz, Marc; Viollet, Benoît; Hallén, Stefan; Rider, Mark H

    2014-06-15

    AMPK (AMP-activated protein kinase) is an attractive therapeutic drug target for treating metabolic disorders. We studied the effects of an AMPK activator developed by Merck (ex229 from patent application WO2010036613), comparing chemical activation with contraction in intact incubated skeletal muscles. We also compared effects of ex229 with those of the Abbott A769662 compound and AICAR (5-amino-4-imidazolecarboxamide riboside). In rat epitrochlearis muscle, ex229 dose-dependently increased AMPK activity of α1-, α2-, β1- and β2-containing complexes with significant increases in AMPK activity seen at a concentration of 50 μM. At a concentration of 100 μM, AMPK activation was similar to that observed after contraction and importantly led to an ~2-fold increase in glucose uptake. In AMPK α1-/α2-catalytic subunit double-knockout myotubes incubated with ex229, the increases in glucose uptake and ACC (acetyl-CoA carboxylase) phosphorylation seen in control cells were completely abolished, suggesting that the effects of the compound were AMPK-dependent. When muscle glycogen levels were reduced by ~50% after starvation, ex229-induced AMPK activation and glucose uptake were amplified in a wortmannin-independent manner. In L6 myotubes incubated with ex229, fatty acid oxidation was increased. Furthermore, in mouse EDL (extensor digitorum longus) and soleus muscles, ex229 increased both AMPK activity and glucose uptake at least 2-fold. In summary, ex229 efficiently activated skeletal muscle AMPK and elicited metabolic effects in muscle appropriate for treating Type 2 diabetes by stimulating glucose uptake and increasing fatty acid oxidation.

  1. 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.

  2. Characterizing the Effects of Chronic 2G Centrifugation on the Rat Skeletal System

    Science.gov (United States)

    Johnson, Aimee; Scott, Ryan; Ronca, April E.; Hoban-Higgins, Tana M.; Fuller, Charles A.; Alwood, Joshua S.

    2017-01-01

    During weightlessness, the skeletal system of astronauts is negatively affected by decreased calcium absorption and bone mass loss. Therefore, it is necessary to counteract these changes for long-term skeletal health during space flights. Our long-term plan is to assess artificial gravity (AG) as a possible solution to mitigate these changes. In this study, we aim to determine the skeletal acclimation to chronic centrifugation. We hypothesize that a 2G hypergravity environment causes an anabolic response in growing male rats. Specifically, we predict chronic 2G to increase tissue mineral density, bone volume fraction of the cancellous tissue and to increase overall bone strength. Systemically, we predict that bone formation markers (i.e., osteocalcin) are elevated and resorption markers (i.e., tartrate resistant acid phosphatase) are decreased or unchanged from controls. The experiment has three groups, each with an n8: chronic 2g, cage control (housed on the centrifuge, but not spun), and a vivarium control (normal rat caging). Pre-pubescent, male Long-Evans rats were used to assess our hypothesis. This group was subject to 90 days of 2G via centrifugation performed at the Chronic Acceleration Research Unit (CARU) at University of California Davis. After 90 days, animals were euthanized and tissues collected. Blood was drawn via cardiac puncture and the right leg collected for structural (via microcomputed tomography) and strength quantification. Understanding how counteract these skeletal changes will have major impacts for both the space-faring astronauts and the people living on Earth.

  3. 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...

  4. 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.)

  5. Distinct Skeletal Muscle Gene Regulation from Active Contraction, Passive Vibration, and Whole Body Heat Stress in Humans.

    Directory of Open Access Journals (Sweden)

    Michael A Petrie

    Full Text Available Skeletal muscle exercise regulates several important metabolic genes in humans. We know little about the effects of environmental stress (heat and mechanical stress (vibration on skeletal muscle. Passive mechanical stress or systemic heat stress are often used in combination with many active exercise programs. We designed a method to deliver a vibration stress and systemic heat stress to compare the effects with active skeletal muscle contraction.The purpose of this study is to examine whether active mechanical stress (muscle contraction, passive mechanical stress (vibration, or systemic whole body heat stress regulates key gene signatures associated with muscle metabolism, hypertrophy/atrophy, and inflammation/repair.Eleven subjects, six able-bodied and five with chronic spinal cord injury (SCI participated in the study. The six able-bodied subjects sat in a heat stress chamber for 30 minutes. Five subjects with SCI received a single dose of limb-segment vibration or a dose of repetitive electrically induced muscle contractions. Three hours after the completion of each stress, we performed a muscle biopsy (vastus lateralis or soleus to analyze mRNA gene expression.We discovered repetitive active muscle contractions up regulated metabolic transcription factors NR4A3 (12.45 fold, PGC-1α (5.46 fold, and ABRA (5.98 fold; and repressed MSTN (0.56 fold. Heat stress repressed PGC-1α (0.74 fold change; p < 0.05; while vibration induced FOXK2 (2.36 fold change; p < 0.05. Vibration similarly caused a down regulation of MSTN (0.74 fold change; p < 0.05, but to a lesser extent than active muscle contraction. Vibration induced FOXK2 (p < 0.05 while heat stress repressed PGC-1α (0.74 fold and ANKRD1 genes (0.51 fold; p < 0.05.These findings support a distinct gene regulation in response to heat stress, vibration, and muscle contractions. Understanding these responses may assist in developing regenerative rehabilitation interventions to improve muscle cell

  6. Contributions of central command and muscle feedback to sympathetic nerve activity in contracting human skeletal muscle

    Directory of Open Access Journals (Sweden)

    Daniel eBoulton

    2016-05-01

    Full Text Available During voluntary contractions, muscle sympathetic nerve activity (MSNA to contracting muscles increases in proportion to force but the underlying mechanisms are not clear. To shed light on these mechanisms, particularly the influences of central command and muscle afferent feedback, the present study tested the hypothesis that MSNA is greater during voluntary compared with electrically-evoked contractions. Seven male subjects performed a series of 1-minute isometric dorsiflexion contractions (left leg separated by 2-minute rest periods, alternating between voluntary and electrically-evoked contractions at similar forces (5-10 % of maximum. MSNA was recorded continuously (microneurography from the left peroneal nerve and quantified from cardiac-synchronised, negative-going spikes in the neurogram. Compared with pre-contraction values, MSNA increased by 51 ± 34 % (P 0.05. MSNA analysed at 15-s intervals revealed that this effect of voluntary contraction appeared 15-30 s after contraction onset (P < 0.01, remained elevated until the end of contraction, and disappeared within 15 s after contraction. These findings suggest that central command, and not feedback from contracting muscle, is the primary mechanism responsible for the increase in MSNA to contracting muscle. The time-course of MSNA suggests that there is a longer delay in the onset of this effect compared with its cessation after contraction.

  7. Benzimidazole derivative small-molecule 991 enhances AMPK activity and glucose uptake induced by AICAR or contraction in skeletal muscle.

    Science.gov (United States)

    Bultot, Laurent; Jensen, Thomas E; Lai, Yu-Chiang; Madsen, Agnete L B; Collodet, Caterina; Kviklyte, Samanta; Deak, Maria; Yavari, Arash; Foretz, Marc; Ghaffari, Sahar; Bellahcene, Mohamed; Ashrafian, Houman; Rider, Mark H; Richter, Erik A; Sakamoto, Kei

    2016-10-01

    AMP-activated protein kinase (AMPK) plays diverse roles and coordinates complex metabolic pathways for maintenance of energy homeostasis. This could be explained by the fact that AMPK exists as multiple heterotrimer complexes comprising a catalytic α-subunit (α1 and α2) and regulatory β (β1 and β2)- and γ (γ1, γ2, γ3)-subunits, which are uniquely distributed across different cell types. There has been keen interest in developing specific and isoform-selective AMPK-activating drugs for therapeutic use and also as research tools. Moreover, establishing ways of enhancing cellular AMPK activity would be beneficial for both purposes. Here, we investigated if a recently described potent AMPK activator called 991, in combination with the commonly used activator 5-aminoimidazole-4-carboxamide riboside or contraction, further enhances AMPK activity and glucose transport in mouse skeletal muscle ex vivo. Given that the γ3-subunit is exclusively expressed in skeletal muscle and has been implicated in contraction-induced glucose transport, we measured the activity of AMPKγ3 as well as ubiquitously expressed γ1-containing complexes. We initially validated the specificity of the antibodies for the assessment of isoform-specific AMPK activity using AMPK-deficient mouse models. We observed that a low dose of 991 (5 μM) stimulated a modest or negligible activity of both γ1- and γ3-containing AMPK complexes. Strikingly, dual treatment with 991 and 5-aminoimidazole-4-carboxamide riboside or 991 and contraction profoundly enhanced AMPKγ1/γ3 complex activation and glucose transport compared with any of the single treatments. The study demonstrates the utility of a dual activator approach to achieve a greater activation of AMPK and downstream physiological responses in various cell types, including skeletal muscle. Copyright © 2016 the American Physiological Society.

  8. Effects of caffeic and chlorogenic acids on the rat skeletal system.

    Science.gov (United States)

    Folwarczna, J; Pytlik, M; Zych, M; Cegieła, U; Nowinska, B; Kaczmarczyk-Sedlak, I; Sliwinski, L; Trzeciak, H; Trzeciak, H I

    2015-02-01

    Caffeic acid, predominantly as esters linked to quinic acid (chlorogenic acids), is a phenolic acid present at high levels in coffee. The aim of the study was to investigate effects of caffeic and chlorogenic acids on the skeletal system of female rats with normal estrogen levels and estrogen-deficient. Caffeic acid (5 and 50 mg/kg p.o. daily) and chlorogenic acid (100 mg/kg p.o. daily) were administered for 4 weeks to non-ovariectomized and bilaterally ovariectomized mature Wistar rats, and their effects were compared with appropriate controls. Moreover, estradiol (0.2 mg/kg p.o. daily) was administered to ovariectomized rats. Bone turnover markers, mass, mineralization and mechanical properties were examined. Although caffeic acid at a low dose exerted some unfavorable effects on the skeletal system, at high doses, caffeic and chlorogenic acids slightly increased mineralization in the tibia and improved mechanical properties of the femoral diaphysis (compact bone). Unlike estradiol, they did not counteract the worsening of the tibial metaphysis bone strength (cancellous bone) and increases in osteocalcin concentration induced by estrogen deficiency. High doses of the phenolic acids slightly favorably affected the rat skeletal system independently of the estrogen status.

  9. Protein kinase C {alpha} activity is important for contraction-induced FXYD1 phosphorylation in skeletal muscle

    DEFF Research Database (Denmark)

    Thomassen, Martin; Rose, Adam John; Jensen, Thomas Elbenhardt

    2011-01-01

    Exercise induced phosphorylation of FXYD1 is a potential important regulator of Na(+), K(+) pump activity. It was investigated if skeletal muscle contractions induce phosphorylation of FXYD1 and if Protein Kinase C a (PKCa) activity is a prerequisite for this possible mechanism. In part 1, human...... muscle biopsies were obtained at rest, after 30 s of high intensity exercise (166±31% of VO(2max)) and after a subsequent 20 min of moderate intensity exercise (79±8% of VO(2max)). In general, FXYD1 phosphorylation was increased compared to rest both after 30 s (P...

  10. Cytoskeletal Tropomyosin Tm5NM1 Is Required for Normal Excitation–Contraction Coupling in Skeletal Muscle

    OpenAIRE

    Vlahovich, Nicole; Kee, Anthony J.; Van der Poel, Chris; Kettle, Emma; Hernandez-Deviez, Delia; Lucas, Christine; Lynch, Gordon S.; Parton, Robert G.; Gunning, Peter W.; Hardeman, Edna C.

    2009-01-01

    The functional diversity of the actin microfilaments relies in part on the actin binding protein tropomyosin (Tm). The muscle-specific Tms regulate actin-myosin interactions and hence contraction. However, there is less known about the roles of the numerous cytoskeletal isoforms. We have shown previously that a cytoskeletal Tm, Tm5NM1, defines a Z-line adjacent cytoskeleton in skeletal muscle. Recently, we identified a second cytoskeletal Tm in this region, Tm4. Here we show that Tm4 and Tm5N...

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

    DEFF Research Database (Denmark)

    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...

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

    Science.gov (United States)

    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.

  13. 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...

  14. 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...

  15. Potentiation of cGMP signaling increases oxygen delivery and oxidative metabolism in contracting skeletal muscle of older but not young humans

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin; Piil, Peter Bergmann; Egelund, Jon

    2015-01-01

    regulation remain unresolved. Cyclic guanosine monophosphate (cGMP) is one of the main second messengers that mediate smooth muscle vasodilation and alterations in cGMP signaling could, therefore, be one mechanism by which skeletal muscle perfusion is impaired with advancing age. The current study aimed...... to evaluate the effect of inhibiting the main enzyme involved in cGMP degradation, phosphodiesterase 5 (PDE5), on blood flow and O2 delivery in contracting skeletal muscle of young and older humans. A group of young (23 ± 1 years) and a group of older (72 ± 2 years) male human subjects performed submaximal...... in the older subjects correlated with the increase in leg O2 uptake (r (2) = 0.843). These findings suggest an insufficient O2 delivery to the contracting skeletal muscle of aged individuals and that reduced cGMP availability is a novel mechanism underlying impaired skeletal muscle perfusion with advancing age....

  16. Role of Active Contraction and Tropomodulins in Regulating Actin Filament Length and Sarcomere Structure in Developing Zebrafish Skeletal Muscle.

    Science.gov (United States)

    Mazelet, Lise; Parker, Matthew O; Li, Mei; Arner, Anders; Ashworth, Rachel

    2016-01-01

    Whilst it is recognized that contraction plays an important part in maintaining the structure and function of mature skeletal muscle, its role during development remains undefined. In this study the role of movement in skeletal muscle maturation was investigated in intact zebrafish embryos using a combination of genetic and pharmacological approaches. An immotile mutant line (cacnb1 (ts25) ) which lacks functional voltage-gated calcium channels (dihydropyridine receptors) in the muscle and pharmacological immobilization of embryos with a reversible anesthetic (Tricaine), allowed the study of paralysis (in mutants and anesthetized fish) and recovery of movement (reversal of anesthetic treatment). The effect of paralysis in early embryos (aged between 17 and 24 hours post-fertilization, hpf) on skeletal muscle structure at both myofibrillar and myofilament level was determined using both immunostaining with confocal microscopy and small angle X-ray diffraction. The consequences of paralysis and subsequent recovery on the localization of the actin capping proteins Tropomodulin 1 & 4 (Tmod) in fish aged from 17 hpf until 42 hpf was also assessed. The functional consequences of early paralysis were investigated by examining the mechanical properties of the larval muscle. The length-force relationship, active and passive tension, was measured in immotile, recovered and control skeletal muscle at 5 and 7 day post-fertilization (dpf). Recovery of muscle function was also assessed by examining swimming patterns in recovered and control fish. Inhibition of the initial embryonic movements (up to 24 hpf) resulted in an increase in myofibril length and a decrease in width followed by almost complete recovery in both moving and paralyzed fish by 42 hpf. In conclusion, myofibril organization is regulated by a dual mechanism involving movement-dependent and movement-independent processes. The initial contractile event itself drives the localization of Tmod1 to its sarcomeric

  17. Role of active contraction and tropomodulins in regulating actin filament length and sarcomere structure in developing zebrafish skeletal muscle

    Directory of Open Access Journals (Sweden)

    Lise eMazelet

    2016-03-01

    Full Text Available Whilst it is recognised that contraction plays an important part in maintaining the structure and function of mature skeletal muscle, its role during development remains undefined. In this study the role of movement in skeletal muscle maturation was investigated in intact zebrafish embryos using a combination of genetic and pharmacological approaches. An immotile mutant line (cacnb1ts25 which lacks functional voltage-gated calcium channels (dihydropyridine receptors in the muscle and pharmacological immobilisation of embryos with a reversible anaesthetic (Tricaine, allowed the study of paralysis (in mutants and anaesthetised fish and recovery of movement (reversal of anaesthetic treatment. The effect of paralysis in early embryos (aged between 17-24 hours post fertilisation, hpf on skeletal muscle structure at both myofibrillar and myofilament level was determined using both immunostaining with confocal microscopy and small angle X-ray diffraction. The consequences of paralysis and subsequent recovery on the localisation of the actin capping proteins Tropomodulin 1 &4 (Tmod in fish aged from 17hpf until 42hpf was also assessed. The functional consequences of early paralysis were investigated by examining the mechanical properties of the larval muscle. The length-force relationship, active and passive tension, was measured in immotile, recovered and control skeletal muscle at 5 and 7 day post fertilisation (dpf. Recovery of muscle function was also assessed by examining swimming patterns in recovered and control fish. Inhibition of the initial embryonic movements (up to 24 hpf resulted in an increase in myofibril length and a decrease in width followed by almost complete recovery in both moving and paralysed fish by 42hpf. In conclusion, myofibril organisation is regulated by a dual mechanism involving movement-dependent and movement-independent processes. The initial contractile event itself drives the localisation of Tmod1 to its sarcomeric

  18. 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.

  19. 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

  20. Cannabinoid signalling inhibits sarcoplasmic Ca2+ release and regulates excitation–contraction coupling in mammalian skeletal muscle

    Science.gov (United States)

    Oláh, Tamás; Bodnár, Dóra; Tóth, Adrienn; Vincze, János; Fodor, János; Reischl, Barbara; Kovács, Adrienn; Ruzsnavszky, Olga; Dienes, Beatrix; Szentesi, Péter; Friedrich, Oliver

    2016-01-01

    Key points Marijuana was found to cause muscle weakness, although the exact regulatory role of its receptors (CB1 cannabinoid receptor; CB1R) in the excitation–contraction coupling (ECC) of mammalian skeletal muscle remains unknown.We found that CB1R activation or its knockout did not affect muscle force directly, whereas its activation decreased the Ca2+‐sensitivity of the contractile apparatus and made the muscle fibres more prone to fatigue.We demonstrate that CB1Rs are not connected to the inositol 1,4,5‐trisphosphate pathway either in myotubes or in adult muscle fibres.By contrast, CB1Rs constitutively inhibit sarcoplasmic Ca2+ release and sarcoplasmic reticulum Ca2+ ATPase during ECC in a Gi/o protein‐mediated way in adult skeletal muscle fibres but not in myotubes.These results help with our understanding of the physiological effects and pathological consequences of CB1R activation in skeletal muscle and may be useful in the development of new cannabinoid drugs. Abstract Marijuana was found to cause muscle weakness, although it is unknown whether it affects the muscles directly or modulates only the motor control of the central nervous system. Although the presence of CB1 cannabinoid receptors (CB1R), which are responsible for the psychoactive effects of the drug in the brain, have recently been demonstrated in skeletal muscle, it is unclear how CB1R‐mediated signalling affects the contraction and Ca²⁺ homeostasis of mammalian skeletal muscle. In the present study, we demonstrate that in vitro CB1R activation increased muscle fatigability and decreased the Ca2+‐sensitivity of the contractile apparatus, whereas it did not alter the amplitude of single twitch contractions. In myotubes, CB1R agonists neither evoked, nor influenced inositol 1,4,5‐trisphosphate (IP3)‐mediated Ca2+ transients, nor did they alter excitation–contraction coupling. By contrast, in isolated muscle fibres of wild‐type mice, although CB1R agonists did not evoke IP3

  1. Cannabinoid signalling inhibits sarcoplasmic Ca2+ release and regulates excitation-contraction coupling in mammalian skeletal muscle.

    Science.gov (United States)

    Oláh, Tamás; Bodnár, Dóra; Tóth, Adrienn; Vincze, János; Fodor, János; Reischl, Barbara; Kovács, Adrienn; Ruzsnavszky, Olga; Dienes, Beatrix; Szentesi, Péter; Friedrich, Oliver; Csernoch, László

    2016-12-15

    Marijuana was found to cause muscle weakness, although the exact regulatory role of its receptors (CB1 cannabinoid receptor; CB1R) in the excitation-contraction coupling (ECC) of mammalian skeletal muscle remains unknown. We found that CB1R activation or its knockout did not affect muscle force directly, whereas its activation decreased the Ca 2+ -sensitivity of the contractile apparatus and made the muscle fibres more prone to fatigue. We demonstrate that CB1Rs are not connected to the inositol 1,4,5-trisphosphate pathway either in myotubes or in adult muscle fibres. By contrast, CB1Rs constitutively inhibit sarcoplasmic Ca 2+ release and sarcoplasmic reticulum Ca 2+ ATPase during ECC in a G i/o protein-mediated way in adult skeletal muscle fibres but not in myotubes. These results help with our understanding of the physiological effects and pathological consequences of CB1R activation in skeletal muscle and may be useful in the development of new cannabinoid drugs. Marijuana was found to cause muscle weakness, although it is unknown whether it affects the muscles directly or modulates only the motor control of the central nervous system. Although the presence of CB1 cannabinoid receptors (CB1R), which are responsible for the psychoactive effects of the drug in the brain, have recently been demonstrated in skeletal muscle, it is unclear how CB1R-mediated signalling affects the contraction and Ca²⁺ homeostasis of mammalian skeletal muscle. In the present study, we demonstrate that in vitro CB1R activation increased muscle fatigability and decreased the Ca 2+ -sensitivity of the contractile apparatus, whereas it did not alter the amplitude of single twitch contractions. In myotubes, CB1R agonists neither evoked, nor influenced inositol 1,4,5-trisphosphate (IP 3 )-mediated Ca 2+ transients, nor did they alter excitation-contraction coupling. By contrast, in isolated muscle fibres of wild-type mice, although CB1R agonists did not evoke IP 3 -mediated Ca 2

  2. Visualization of dynamic change in contraction-induced lipid composition in mouse skeletal muscle by matrix-assisted laser desorption/ionization imaging mass spectrometry.

    Science.gov (United States)

    Goto-Inoue, Naoko; Manabe, Yasuko; Miyatake, Shouta; Ogino, Shinya; Morishita, Ai; Hayasaka, Takahiro; Masaki, Noritaka; Setou, Mitsutoshi; Fujii, Nobuharu L

    2012-06-01

    Lipids in skeletal muscle play a fundamental role both in normal muscle metabolism and in disease states. Skeletal muscle lipid accumulation is associated with several chronic metabolic disorders, including obesity, insulin resistance, and type 2 diabetes. However, it is poorly understood whether the lipid composition of skeletal muscle changes by contraction, due to the complexity of lipid molecular species. In this study, we used matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) to investigate changes in skeletal muscle lipid composition induced by contraction. We successfully observed the reduction of diacylglycerol and triacylglycerol, which are generally associated with muscle contraction. Interestingly, we found the accumulation of some saturated and mono-unsaturated fatty acids and poly-unsaturated fatty acids containing phosphatidylcholine in contracted muscles. Moreover, the distributions of several types of lipid were changed by contraction. Our results show that changes in the lipid amount, lipid composition, and energy metabolic activity can be evaluated in each local spot of cells and tissues at the same time using MALDI-IMS. In conclusion, MALDI-IMS is a powerful tool for studying lipid changes associated with contractions.

  3. Skeletal growth and long-term bone turnover after enterocystoplasty in a chronic rat model

    DEFF Research Database (Denmark)

    Gerharz, E.W.; Gasser, J.A.; Mosekilde, Li.

    2003-01-01

    OBJECTIVE: To investigate skeletal growth and bone metabolism in a chronic animal model of urinary diversion.MATERIALS AND METHODS: Young male Wistar rats (120) were allocated randomly to four groups undergoing: ileocystoplasty, ileocystoplasty and resection of the ileocaecal segment, colocystopl......OBJECTIVE: To investigate skeletal growth and bone metabolism in a chronic animal model of urinary diversion.MATERIALS AND METHODS: Young male Wistar rats (120) were allocated randomly to four groups undergoing: ileocystoplasty, ileocystoplasty and resection of the ileocaecal segment...... mass ex vivo.RESULTS: Most (90%) of the rats survived the study period (8 months); six rats died from bowel obstruction at the level of the entero-anastomosis and four had to be killed because of persistent severe diarrhoea. Vital intestinal mucosa was found in all augmented bladders. There were...... no differences in bone length and volume. Loss of bone mass was almost exclusively in rats with ileocystoplasty and resection of the ileocaecal segment (-37.5%, pQCT, P

  4. 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.

  5. Contraction-evoked vasodilation and functional hyperaemia are compromised in branching skeletal muscle arterioles of young pre-diabetic mice.

    Science.gov (United States)

    Novielli, N M; Jackson, D N

    2014-06-01

    To investigate the effects of pre-diabetes on microvascular network function in contracting skeletal muscle. We hypothesized that pre-diabetes compromises contraction-evoked vasodilation of branching second-order (2A), third-order (3A) and fourth-order (4A) arterioles, where distal arterioles would be affected the greatest. Intravital video microscopy was used to measure arteriolar diameter (in 2A, 3A and 4A) and blood flow (in 2A and 3A) changes to electrical field stimulation of the gluteus maximus muscle in pre-diabetic (The Pound Mouse, PD) and control (c57bl6, CTRL) mice. Baseline diameter and blood flow were similar between groups (2A: ~20 μm, 3A: ~14 μm and 4A: ~8 μm; 2A: ~1 nL s(-1) and 3A: ~0.5 nL s(-1) ). Single tetanic contraction (100 Hz; 200, 400, 800 ms duration) evoked rapid-onset vasodilation (ROV) and blood flow responses that were blunted by ~50% and up to 81%, respectively, in PD vs. CTRL (P contraction (2 and 8 Hz, 30 s) evoked vasodilatory and blood flow responses that were also attenuated by ~50% and up to 71%, respectively, in PD vs. CTRL (P contraction was also up to 2.5-fold greater at 4A vs. 2A in CTRL; however spatial differences in vasodilation across arteriolar branch orders was disrupted in PD. Arteriolar dysregulation in pre-diabetes causes deficits in contraction-evoked dilation and blood flow, where greatest deficits occur at distal arterioles. © 2014 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

  6. 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

  7. Capillary response to skeletal muscle contraction: evidence that redundancy between vasodilators is physiologically relevant during active hyperaemia.

    Science.gov (United States)

    Lamb, Iain R; Novielli, Nicole M; Murrant, Coral L

    2018-04-15

    The current theory behind matching blood flow to metabolic demand of skeletal muscle suggests redundant interactions between metabolic vasodilators. Capillaries play an important role in blood flow control given their ability to respond to muscle contraction by causing conducted vasodilatation in upstream arterioles that control their perfusion. We sought to determine whether redundancies occur between vasodilators at the level of the capillary by stimulating the capillaries with muscle contraction and vasodilators relevant to muscle contraction. We identified redundancies between potassium and both adenosine and nitric oxide, between nitric oxide and potassium, and between adenosine and both potassium and nitric oxide. During muscle contraction, we demonstrate redundancies between potassium and nitric oxide as well as between potassium and adenosine. Our data show that redundancy is physiologically relevant and involved in the coordination of the vasodilator response during muscle contraction at the level of the capillaries. We sought to determine if redundancy between vasodilators is physiologically relevant during active hyperaemia. As inhibitory interactions between vasodilators are indicative of redundancy, we tested whether vasodilators implicated in mediating active hyperaemia (potassium (K + ), adenosine (ADO) and nitric oxide (NO)) inhibit one another's vasodilatory effects through direct application of pharmacological agents and during muscle contraction. Using the hamster cremaster muscle and intravital microscopy, we locally stimulated capillaries with one vasodilator in the absence and the presence of a second vasodilator (10 -7 m S-nitroso-N-acetylpenicillamine (SNAP), 10 -7 m ADO, 10 mm KCl) applied sequentially and simultaneously, and observed the response in the associated upstream 4A arteriole controlling the perfusion of the stimulated capillary. We found that KCl significantly attenuated SNAP- and ADO-induced vasodilatations by ∼49.7% and

  8. Finite element model of intermuscular pressure during isometric contraction of skeletal muscle

    NARCIS (Netherlands)

    Jenkyn, T.R.; Koopman, B.; Huijing, P.A.J.B.M.; Lieber, R.L.; Kaufman, K.R.

    2002-01-01

    The measurement of in vivo intramuscular pressure (IMP) has recently become practical and IMP appears well correlated with muscle tension. A numerical model of skeletal muscle was developed to examine the mechanisms producing IMP. Unipennate muscle is modelled as a two-dimensional material continuum

  9. 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.

  10. 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

  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. Spatial interaction between tissue pressure and skeletal muscle perfusion during contraction

    NARCIS (Netherlands)

    Donkelaar, van C.C.; Huyghe, J.M.R.J.; Vankan, W.J.; Drost, M.R.

    2001-01-01

    The vascular waterfall theory attributes decreased muscle perfusion during contraction to increased intramuscular pressure (P_IM ) and concomitant increase in venous resistance. Although P_IM is distributed during contractions, this theory does not account for heterogeneity.This study hypothesises

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

    Directory of Open Access Journals (Sweden)

    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. Charge Movement in a Fast Twitch Skeletal Muscle from Rat

    OpenAIRE

    Simon, B. J.; Beam, K. G.

    1983-01-01

    Voltage-dependent charge movement in the rat omohyoid muscle was investigated using the three microelectrode voltage clamp technique. The charge that moved during a depolarization from the holding potential (-90 mV) to the test potential, V, increased with increasing V, saturating around 0 mV. The charge vs. voltage relationship was well fitted by Q = Qmax/{1 + exp[-(V - V)/k]}, with Qmax = 28.5 nC/μF, V = -34.2 mV, and k = 8.7 mV. Repolarization of the fiber from the test potential back to t...

  15. 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.

  16. Skeletal muscle PLIN proteins, ATGL and CGI-58, interactions at rest and following stimulated contraction

    OpenAIRE

    MacPherson, Rebecca E. K.; Ramos, Sofhia V.; Vandenboom, Rene; Roy, Brian D.; Peters, Sandra J.

    2013-01-01

    Evidence indicates that skeletal muscle lipid droplet-associated proteins (PLINs) regulate lipolysis through protein-protein interactions on the lipid droplet surface. In adipocytes, PLIN1 is thought to regulate lipolysis by directly interacting with comparative gene identification-58 (CGI-58), an activator of adipose triglyceride lipase (ATGL). Upon lipolytic stimulation, PLIN1 is phosphorylated, releasing CGI-58 to fully activate ATGL and initiate triglyceride breakdown. The absence of PLIN...

  17. Connective tissue regeneration in skeletal muscle after eccentric contraction-induced injury

    DEFF Research Database (Denmark)

    Mackey, Abigail Louise; Kjaer, Michael

    2017-01-01

    Human skeletal muscle has the potential to regenerate completely after injury induced under controlled experimental conditions. The events inside the myofibres as they undergo necrosis, followed closely by satellite cell mediated myogenesis, have been mapped in detail. Much less is known about...... the adaptation throughout this process of both the connective tissue structures surrounding the myofibres, and the fibroblasts, the cells responsible for synthesising this connective tissue. However, the few studies investigating muscle connective tissue remodelling demonstrate a strong response that appears...

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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

  20. Skeletal Effects of the Saturated 3-Thia Fatty Acid Tetradecylthioacetic Acid in Rats

    Directory of Open Access Journals (Sweden)

    Astrid Kamilla Stunes

    2011-01-01

    Full Text Available This study explores the skeletal effects of the peroxisome proliferator activated receptor (PPARpan agonist tetradecylthioacetic acid (TTA. Rats, without (Study I and with ovariectomy (OVX or sham operation (Study II, were given TTA or vehicle daily for 4 months. Bone markers in plasma, whole body and femoral bone mineral density and content (BMD and BMC, and body composition were examined. Histomorphometric and biomechanical analyses (Study I and biomechanical and μCT analyses (Study II of the femur were performed. Normal rats fed TTA had higher femoral BMD and increased total and cortical area in femur compared to controls. The ovariectomized groups had decreased BMD and impaired microarchitecture parameters compared to SHAM. However, the TTA OVX group maintained femoral BMC, trabecular thickness in the femoral head, and cortical volume in the femoral metaphysis as SHAM. TTA might increase BMD and exert a light preventive effect on estrogen-related bone loss in rats.

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

    Directory of Open Access Journals (Sweden)

    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.

  2. Preconditioning of skeletal muscle against contraction-induced damage: the role of adaptations to oxidants in mice.

    Science.gov (United States)

    McArdle, F; Spiers, S; Aldemir, H; Vasilaki, A; Beaver, A; Iwanejko, L; McArdle, A; Jackson, M J

    2004-11-15

    Adaptations of skeletal muscle following exercise are accompanied by changes in gene expression, which can result in protection against subsequent potentially damaging exercise. One cellular signal activating these adaptations may be an increased production of reactive oxygen and nitrogen species (ROS). The aim of this study was to examine the effect of a short period of non-damaging contractions on the subsequent susceptibility of muscle to contraction-induced damage and to examine the changes in gene expression that occur following the initial contraction protocol. Comparisons with changes in gene expression in cultured myotubes following treatment with a non-damaging concentration of hydrogen peroxide (H(2)O(2)) were used to identify redox-sensitive genes whose expression may be modified by the increased ROS production during contractions. Hindlimb muscles of mice were subjected to a preconditioning, non-damaging isometric contraction protocol in vivo. After 4 or 12 h, extensor digitorum longus (EDL) and soleus muscles were removed and subjected to a (normally) damaging contraction protocol in vitro. Muscles were also analysed for changes in gene expression induced by the preconditioning protocol using cDNA expression techniques. In a parallel study, C(2)C(12) myotubes were treated with a non-damaging concentration (100 microM) of H(2)O(2) and, at 4 and 12 h following treatment, myotubes were treated with a damaging concentration of H(2)O(2) (2 mM). Myotubes were analysed for changes in gene expression at 4 h following treatment with 100 microM H(2)O(2) alone. Data demonstrate that a prior period of non-damaging contractile activity resulted in significant protection of EDL and soleus muscles against a normally damaging contraction protocol 4 h later. This protection was associated with significant changes in gene expression. Prior treatment of myotubes with a non-damaging concentration of H(2)O(2) also resulted in significant protection against a damaging

  3. Supplementation with vitamins C and E inhibits the release of interleukin-6 from contracting human skeletal muscle

    DEFF Research Database (Denmark)

    Fischer, Christian P; Hiscock, Natalie J; Penkowa, Milena

    2004-01-01

    (6 h). Leg blood flow was measured using Doppler ultrasonography. Plasma IL-6 concentration was measured in blood sampled from the femoral artery and vein. The net release of IL-6 was calculated using Fick's principle. Plasma vitamin C and E concentrations were elevated in Treatment compared...... in Control, but not in Treatment. In conclusion, our results show that supplementation with vitamins C and E attenuated the systemic IL-6 response to exercise primarily via inhibition of the IL-6 protein release from the contracting skeletal muscle per se....... (Treatment versus Control: 7.9 pg ml(-1), 95% confidence interval (CI) 6.0-10.7 pg ml(-1), versus 19.7 pg ml(-1), CI 13.8-29.4 pg ml(-1), at 3.5 h, P C-reactive protein and cortisol levels all increased after the exercise...

  4. Human Skeletal Muscle Stem Cells in Adaptations to Exercise; Effects of Resistance Exercise Contraction Mode and Protein Supplementation

    DEFF Research Database (Denmark)

    Farup, Jean

    2014-01-01

    the effect of contraction mode specific resistance training and protein supplementation on whole muscle and tendon hypertrophy. Quadriceps muscle and patellar tendon cross-sectional area (CSA) was quantified using magnetic resonance imaging pre and post 12 weeks of eccentric (Ecc) or concentric (Conc...... concentric resistance training and ingestion of protein influence myocellular adaptations, with special emphasis on muscle stem cell adaptations, during both acute and prolonged resistance exercise in human skeletal muscle. Paper I. Whey protein supplementation accelerates satellite cell proliferation during...... recovery from eccentric exercise In paper I, we evaluated the effect of a single bout of unaccustomed eccentric exercise on fiber type specific SC content by immunohistochemistry. Subjects received either hydrolysed whey protein (Whey) or iso-caloric carbohydrate (Placebo) in the days post eccentric...

  5. Exercise training improves blood flow to contracting skeletal muscle of older men via enhanced cGMP signaling

    DEFF Research Database (Denmark)

    Piil, Peter Bergmann; Smith Jørgensen, Tue; Egelund, Jon

    2018-01-01

    Physical activity has the potential to offset age-related impairments in the regulation of blood flow and O2 delivery to the exercising muscles; however, the mechanisms underlying this effect of physical activity remain poorly understood. The present study examined the role of cGMP in training...... a period of aerobic high-intensity exercise training. To determine the role of cGMP signaling, pharmacological inhibition of phosphodiesterase 5 (PDE5) was performed. Before training, inhibition of PDE5 increased (P... group; however, these effects of PDE5 inhibition were not detected after training. These findings suggest a role for enhanced cGMP signaling in the training-induced improvement of regulation of blood flow in contracting skeletal muscle of older men....

  6. Leptin administration affects growth and skeletal development in a rat intrauterine growth restriction model: preliminary study.

    Science.gov (United States)

    Bar-El Dadon, Shimrit; Shahar, Ron; Katalan, Vered; Monsonego-Ornan, Efrat; Reifen, Ram

    2011-09-01

    Skeletal abnormalities are one of the hallmarks of growth delay during gestation. The aim of this study was to determine changes induced by leptin in skeletal growth and development in a rat model of intrauterine growth retardation (IUGR) and to elucidate the possible underlying mechanisms. Intrauterine growth retardation was induced prepartum and the effects of leptin to mothers prenatally or to offspring postnatally were studied. Radii were harvested and tested mechanically and structurally. Tibias were evaluated for growth-plate morphometry. On day 40 postpartum, total bone length and mineral density and tibial growth-plate width and numbers of cells within its zones of offspring treated with leptin were significantly greater than in the control group. Postnatal leptin administration in an IUGR model improves the structural properties and elongation rate of bone. These findings could pave the way to preventing some phenotypic presentations of IUGR. Copyright © 2011 Elsevier Inc. All rights reserved.

  7. 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...

  8. Physical interaction of junctophilin and the CaV1.1 C terminus is crucial for skeletal muscle contraction.

    Science.gov (United States)

    Nakada, Tsutomu; Kashihara, Toshihide; Komatsu, Masatoshi; Kojima, Katsuhiko; Takeshita, Toshikazu; Yamada, Mitsuhiko

    2018-04-24

    Close physical association of Ca V 1.1 L-type calcium channels (LTCCs) at the sarcolemmal junctional membrane (JM) with ryanodine receptors (RyRs) of the sarcoplasmic reticulum (SR) is crucial for excitation-contraction coupling (ECC) in skeletal muscle. However, the molecular mechanism underlying the JM targeting of LTCCs is unexplored. Junctophilin 1 (JP1) and JP2 stabilize the JM by bridging the sarcolemmal and SR membranes. Here, we examined the roles of JPs in localization and function of LTCCs. Knockdown of JP1 or JP2 in cultured myotubes inhibited LTCC clustering at the JM and suppressed evoked Ca 2+ transients without disrupting JM structure. Coimmunoprecipitation and GST pull-down assays demonstrated that JPs physically interacted with 12-aa residues in the proximal C terminus of the Ca V 1.1. A JP1 mutant lacking the C terminus including the transmembrane domain (JP1ΔCT) interacted with the sarcolemmal/T-tubule membrane but not the SR membrane. Expression of this mutant in adult mouse muscles in vivo exerted a dominant-negative effect on endogenous JPs, impairing LTCC-RyR coupling at triads without disrupting JM morphology, and substantially reducing Ca 2+ transients without affecting SR Ca 2+ content. Moreover, the contractile force of the JP1ΔCT-expressed muscle was dramatically reduced compared with the control. Taken together, JPs recruit LTCCs to the JM through physical interaction and ensure robust ECC at triads in skeletal muscle.

  9. NRIP is newly identified as a Z-disc protein, activating calmodulin signaling for skeletal muscle contraction and regeneration.

    Science.gov (United States)

    Chen, Hsin-Hsiung; Chen, Wen-Pin; Yan, Wan-Lun; Huang, Yuan-Chun; Chang, Szu-Wei; Fu, Wen-Mei; Su, Ming-Jai; Yu, I-Shing; Tsai, Tzung-Chieh; Yan, Yu-Ting; Tsao, Yeou-Ping; Chen, Show-Li

    2015-11-15

    Nuclear receptor interaction protein (NRIP, also known as DCAF6 and IQWD1) is a Ca(2+)-dependent calmodulin-binding protein. In this study, we newly identify NRIP as a Z-disc protein in skeletal muscle. NRIP-knockout mice were generated and found to have reduced muscle strength, susceptibility to fatigue and impaired adaptive exercise performance. The mechanisms of NRIP-regulated muscle contraction depend on NRIP being downstream of Ca(2+) signaling, where it stimulates activation of both 'calcineurin-nuclear factor of activated T-cells, cytoplasmic 1' (CaN-NFATc1; also known as NFATC1) and calmodulin-dependent protein kinase II (CaMKII) through interaction with calmodulin (CaM), resulting in the induction of mitochondrial activity and the expression of genes encoding the slow class of myosin, and in the regulation of Ca(2+) homeostasis through the internal Ca(2+) stores of the sarcoplasmic reticulum. Moreover, NRIP-knockout mice have a delayed regenerative capacity. The amount of NRIP can be enhanced after muscle injury and is responsible for muscle regeneration, which is associated with the increased expression of myogenin, desmin and embryonic myosin heavy chain during myogenesis, as well as for myotube formation. In conclusion, NRIP is a novel Z-disc protein that is important for skeletal muscle strength and regenerative capacity. © 2015. Published by The Company of Biologists Ltd.

  10. 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.

  11. Sonomyography Analysis on Thickness of Skeletal Muscle During Dynamic Contraction Induced by Neuromuscular Electrical Stimulation: A Pilot Study.

    Science.gov (United States)

    Qiu, Shuang; Feng, Jing; Xu, Jiapeng; Xu, Rui; Zhao, Xin; Zhou, Peng; Qi, Hongzhi; Zhang, Lixin; Ming, Dong

    2017-01-01

    Neuromuscular electrical stimulation (NMES) that stimulates skeletal muscles to induce contractions has been widely applied to restore functions of paralyzed muscles. However, the architectural changes of stimulated muscles induced by NMES are still not well understood. The present study applies sonomyography (SMG) to evaluate muscle architecture under NMES-induced and voluntary movements. The quadriceps muscles of seven healthy subjects were tested for eight cycles during an extension exercise of the knee joint with/without NMES, and SMG and the knee joint angle were recorded during the process of knee extension. A least squares support vector machine (LS-SVM) LS-SVM model was developed and trained using the data sets of six cycles collected under NMES, while the remaining data was used to test. Muscle thickness changes were extracted from ultrasound images and compared between NMES-induced and voluntary contractions, and LS-SVM was used to model a relationship between dynamical knee joint angles and SMG signals. Muscle thickness showed to be significantly correlated with joint angle in NMES-induced contractions, and a significant negative correlation was observed between Vastus intermedius (VI) thickness and rectus femoris (RF) thickness. In addition, there was a significant difference between voluntary and NMES-induced contractions . The LS-SVM model based on RF thickness and knee joint angle provided superior performance compared with the model based on VI thickness and knee joint angle or total thickness and knee joint angle. This suggests that a strong relation exists between the RF thickness and knee joint angle. These results provided direct evidence for the potential application of RF thickness in optimizing NMES system as well as measuring muscle state under NMES.

  12. Enhanced Glycogen Storage of a Subcellular Hot Spot in Human Skeletal Muscle during Early Recovery from Eccentric Contractions

    Science.gov (United States)

    Nielsen, Joachim; Farup, Jean; Rahbek, Stine Klejs; de Paoli, Frank Vincenzo; Vissing, Kristian

    2015-01-01

    Unaccustomed eccentric exercise is accompanied by muscle damage and impaired glucose uptake and glycogen synthesis during subsequent recovery. Recently, it was shown that the role and regulation of glycogen in skeletal muscle are dependent on its subcellular localization, and that glycogen synthesis, as described by the product of glycogen particle size and number, is dependent on the time course of recovery after exercise and carbohydrate availability. In the present study, we investigated the subcellular distribution of glycogen in fibers with high (type I) and low (type II) mitochondrial content during post-exercise recovery from eccentric contractions. Analysis was completed on five male subjects performing an exercise bout consisting of 15 x 10 maximal eccentric contractions. Carbohydrate-rich drinks were subsequently ingested throughout a 48 h recovery period and muscle biopsies for analysis included time points 3, 24 and 48 h post exercise from the exercising leg, whereas biopsies corresponding to prior to and at 48 h after the exercise bout were collected from the non-exercising, control leg. Quantitative imaging by transmission electron microscopy revealed an early (post 3 and 24 h) enhanced storage of intramyofibrillar glycogen (defined as glycogen particles located within the myofibrils) of type I fibers, which was associated with an increase in the number of particles. In contrast, late in recovery (post 48 h), intermyofibrillar, intramyofibrillar and subsarcolemmal glycogen in both type I and II fibers were lower in the exercise leg compared with the control leg, and this was associated with a smaller size of the glycogen particles. We conclude that in the carbohydrate-supplemented state, the effect of eccentric contractions on glycogen metabolism depends on the subcellular localization, muscle fiber’s oxidative capacity, and the time course of recovery. The early enhanced storage of intramyofibrillar glycogen after the eccentric contractions may

  13. 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

  14. 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.

  15. 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

  16. Involvement of Rac1 and the actin cytoskeleton in insulin- and contraction-stimulated intracellular signaling and glucose uptake in mature skeletal muscle

    DEFF Research Database (Denmark)

    Sylow, Lykke

    understood. The aim of the current PhD was therefore to investigate the involvement of Rac1 and the actin cytoskeleton in the regulation of insulin- and contraction-stimulated glucose uptake in mature skeletal muscle. The central findings of this PhD thesis was that Rac1 was activated by both insulin...

  17. 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.

  18. 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

  19. Contraction and AICAR Stimulate IL-6 Vesicle Depletion From Skeletal Muscle Fibers In Vivo

    DEFF Research Database (Denmark)

    Lauritzen, Hans P M M; Brandauer, Josef; Schjerling, Peter

    2013-01-01

    muscle fibers and in live animals in vivo. Using confocal imaging to visualize endogenous IL-6 protein in fixed muscle fibers, we found IL-6 in small vesicle structures distributed throughout the fibers under basal (resting) conditions. To determine the kinetics of IL-6 secretion, intact quadriceps...... muscles were transfected with enhanced green fluorescent protein (EGFP)-tagged IL-6 (IL-6-EGFP), and 5 days later anesthetized mice were imaged before and after muscle contractions in situ. Contractions decreased IL-6-EGFP-containing vesicles and protein by 62% (P

  20. Radiometrical, hormonal and biological correlates of skeletal growth in the female rat from birth to senescence.

    Science.gov (United States)

    del Pozo, Emilio; Janner, Marco; Mackenzie, Andrew R; Arampatzis, Spyridon; Dixon, Arnold K; Perrelet, Romain; Ruch, Walter; Lippuner, Kurt; Zapf, Juergen; Lamberts, Steven W; Mullis, Primus E

    2014-01-01

    We investigated the skeletal growth profile of female rats from birth to senescence (100weeks) on the basis of sequential radiometrical, hormonal and biochemical parameters. Weaning rats entered the study which was divided into two sections: a) sequential measurements of vertebral and tibial growths and bone mineral density (BMD), estimation of mineral content of the entire skeleton (BMC) and chemical analysis of vertebral Ca; and b) determination of basal and pulsatile growth hormone (rGH), insulin-like growth hormone (IGF-I), estradiol (E2), parathyroid hormone (PTH), osteocalcin (OC) and urinary d-pyridinoline (dp) throughout the experimental period. Vertebral and tibial growths ceased at week 25 whereas BMD and BMC as well as total vertebral Ca exhibited a peak bone mass at week 40. rGH pulsatile profiles were significantly higher in younger animals coinciding with the period of active growth and IGF-I peaked at 7weeks, slowly declining thereafter and stabilizing after week 60. OC and dp closely paralleled IGF-I coinciding with the period of enhanced skeletal growth, remaining thereafter in the low range indicative of reduced bone turnover. E2 increased during reproductive life but the lower values subsequently recorded were still in the physiological range, strongly suggesting a protective role of this steroid on bone remodeling. PTH followed a similar profile to E2, but the significance of this after completion of growth remains unclear. Mechanisms governing skeletal growth in the female rat appear similar to those in humans. Bone progression and attainment of peak bone mass are under simultaneous control of rGH, IGF-I and calciotropic hormones and are modulated by E2. This steroid seems to protect the skeleton from resorption before senescence whereas the role of PTH in this context remains uncertain. Copyright © 2014. Published by Elsevier Ltd.

  1. 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.

  2. 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.

  3. Electromechanical delay components during skeletal muscle contraction and relaxation in patients with myotonic dystrophy type 1.

    Science.gov (United States)

    Esposito, Fabio; Cè, Emiliano; Rampichini, Susanna; Limonta, Eloisa; Venturelli, Massimo; Monti, Elena; Bet, Luciano; Fossati, Barbara; Meola, Giovanni

    2016-01-01

    The electromechanical delay during muscle contraction and relaxation can be partitioned into mainly electrochemical and mainly mechanical components by an EMG, mechanomyographic, and force combined approach. Component duration and measurement reliability were investigated during contraction and relaxation in a group of patients with myotonic dystrophy type 1 (DM1, n = 13) and in healthy controls (n = 13). EMG, mechanomyogram, and force were recorded in DM1 and in age- and body-matched controls from tibialis anterior (distal muscle) and vastus lateralis (proximal muscle) muscles during maximum voluntary and electrically-evoked isometric contractions. The electrochemical and mechanical components of the electromechanical delay during muscle contraction and relaxation were calculated off-line. Maximum strength was significantly lower in DM1 than in controls under both experimental conditions. All electrochemical and mechanical components were significantly longer in DM1 in both muscles. Measurement reliability was very high in both DM1 and controls. The high reliability of the measurements and the differences between DM1 patients and controls suggest that the EMG, mechanomyographic, and force combined approach could be utilized as a valid tool to assess the level of neuromuscular dysfunction in this pathology, and to follow the efficacy of pharmacological or non-pharmacological interventions. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Opposite effect of ATP on contraction force of tonic and phasic skeletal muscles in frogs.

    Science.gov (United States)

    Grishin, S N; Kamaliev, R R; Teplov, A Yu; Ziganshin, A U

    2011-07-01

    Experiments in vitro showed that ATP and adenosine equally suppressed contractions of frog m. sartorius, which belongs to the phasic type muscles. Adenosine receptors antagonist 8-SPT abolished the effect of adenosine, but did not change the effect of ATP. This fact proves the independence of signaling pathways of these purines. ATP produced an opposite effect on the tonic muscle m. cruralis and increased the force of its contraction. Adenosine produced an inhibitory effect on the force of m. cruralis contration. In this case, 8-SPT also eliminated the effect of adenosine, but did not change the effect of ATP. The potentiating effect of ATP was blocked by suramin, a nonselective antagonist of P2 receptors, which attests to their involvement into the effects of this purine. The opposite effects of purinergic regulation reflect fundamental differences in functional organization of phasic and tonic muscular systems. It was hypothesized that the increase in contraction force under the effect of ATP is a mechanism providing maitenance of the contracted state of tonic muscle without appreciable metabolic costs.

  5. Caffeine at a Moderate Dose Did Not Affect the Skeletal System of Rats with Streptozotocin-Induced Diabetes.

    Science.gov (United States)

    Folwarczna, Joanna; Janas, Aleksandra; Cegieła, Urszula; Pytlik, Maria; Śliwiński, Leszek; Matejczyk, Magdalena; Nowacka, Anna; Rudy, Karolina; Krivošíková, Zora; Štefíková, Kornélia; Gajdoš, Martin

    2017-10-30

    Diabetes may lead to the development of osteoporosis. Coffee drinking, apart from its health benefits, is taken into consideration as an osteoporosis risk factor. Data from human and animal studies on coffee and caffeine bone effects are inconsistent. The aim of the study was to investigate effects of caffeine at a moderate dose on the skeletal system of rats in two models of experimental diabetes induced by streptozotocin. Effects of caffeine administered orally (20 mg/kg aily for four weeks) were investigated in three-month-old female Wistar rats, which, two weeks before the start of caffeine administration, received streptozotocin (60 mg/kg, intraperitoneally) alone or streptozotocin after nicotinamide (230 mg/kg, intraperitoneally). Bone turnover markers, mass, mineral density, histomorphometric parameters, and mechanical properties were examined. Streptozotocin induced diabetes, with profound changes in the skeletal system due to increased bone resorption and decreased bone formation. Although streptozotocin administered after nicotinamide induced slight increases in glucose levels at the beginning of the experiment only, slight, but significant unfavorable changes in the skeletal system were demonstrated. Administration of caffeine did not affect the investigated skeletal parameters of rats with streptozotocin-induced disorders. In conclusion, caffeine at a moderate dose did not exert a damaging effect on the skeletal system of diabetic rats.

  6. Caffeine at a Moderate Dose Did Not Affect the Skeletal System of Rats with Streptozotocin-Induced Diabetes

    Directory of Open Access Journals (Sweden)

    Joanna Folwarczna

    2017-10-01

    Full Text Available Diabetes may lead to the development of osteoporosis. Coffee drinking, apart from its health benefits, is taken into consideration as an osteoporosis risk factor. Data from human and animal studies on coffee and caffeine bone effects are inconsistent. The aim of the study was to investigate effects of caffeine at a moderate dose on the skeletal system of rats in two models of experimental diabetes induced by streptozotocin. Effects of caffeine administered orally (20 mg/kg aily for four weeks were investigated in three-month-old female Wistar rats, which, two weeks before the start of caffeine administration, received streptozotocin (60 mg/kg, intraperitoneally alone or streptozotocin after nicotinamide (230 mg/kg, intraperitoneally. Bone turnover markers, mass, mineral density, histomorphometric parameters, and mechanical properties were examined. Streptozotocin induced diabetes, with profound changes in the skeletal system due to increased bone resorption and decreased bone formation. Although streptozotocin administered after nicotinamide induced slight increases in glucose levels at the beginning of the experiment only, slight, but significant unfavorable changes in the skeletal system were demonstrated. Administration of caffeine did not affect the investigated skeletal parameters of rats with streptozotocin-induced disorders. In conclusion, caffeine at a moderate dose did not exert a damaging effect on the skeletal system of diabetic rats.

  7. Catch-slip bonds can be dispensable for motor force regulation during skeletal muscle contraction

    Science.gov (United States)

    Dong, Chenling; Chen, Bin

    2015-07-01

    It is intriguing how multiple molecular motors can perform coordinated and synchronous functions, which is essential in various cellular processes. Recent studies on skeletal muscle might have shed light on this issue, where rather precise motor force regulation was partly attributed to the specific stochastic features of a single attached myosin motor. Though attached motors can randomly detach from actin filaments either through an adenosine triphosphate (ATP) hydrolysis cycle or through "catch-slip bond" breaking, their respective contribution in motor force regulation has not been clarified. Here, through simulating a mechanical model of sarcomere with a coupled Monte Carlo method and finite element method, we find that the stochastic features of an ATP hydrolysis cycle can be sufficient while those of catch-slip bonds can be dispensable for motor force regulation.

  8. Phosphocreatine kinetics at the onset of contractions in skeletal muscle of MM creatine kinase knockout mice

    Science.gov (United States)

    Roman, Brian B.; Meyer, Ronald A.; Wiseman, Robert W.

    2002-01-01

    Phosphocreatine (PCr) depletion during isometric twitch stimulation at 5 Hz was measured by (31)P-NMR spectroscopy in gastrocnemius muscles of pentobarbital-anesthetized MM creatine kinase knockout (MMKO) vs. wild-type C57B (WT) mice. PCr depletion after 2 s of stimulation, estimated from the difference between spectra gated to times 200 ms and 140 s after 2-s bursts of contractions, was 2.2 +/- 0.6% of initial PCr in MMKO muscle vs. 9.7 +/- 1.6% in WT muscles (mean +/- SE, n = 7, P muscle after 2 s only if ADP-stimulated oxidative phosphorylation was included in the model. Taken together, the results suggest that cytoplasmic ADP more rapidly increases and oxidative phosphorylation is more rapidly activated at the onset of contractions in MMKO compared with WT muscles.

  9. Significance of insulin for glucose metabolism in skeletal muscle during contractions

    DEFF Research Database (Denmark)

    Hespel, P; Vergauwen, Lieven; Vandenberghe, K

    1996-01-01

    is essentially effected via increased blood flow, significantly contributes to stimulate glucose uptake. Again, however, increased glucose delivery appears to be a more potent stimulus of muscle glucose uptake as the circulating insulin level is increased. Furthermore, contractions and elevated flow prove...... is effected primarily via mechanisms exerted within the muscle cell related to the contractile activity per se. Yet contractions become a more potent stimulus of muscle glucose uptake as the plasma insulin level is increased. In addition, enhanced glucose delivery to muscle, which during exercise...... to be additive stimuli of muscle glucose uptake at any plasma insulin level. In conclusion, the extent to which muscle glucose uptake is stimulated during exercise depends on various factors, including 1) the intensity of the contractile activity, 2) the magnitude of the exercise-associated increase in muscle...

  10. Skeletal muscle collagen content in humans after high-force eccentric contractions

    DEFF Research Database (Denmark)

    Mackey, Abigail; Donnelly, Alan E; Turpeenniemi-Hujanen, Taina

    2004-01-01

    The purpose of this study was to investigate the effects of high-force eccentric muscle contractions on collagen remodeling and on circulating levels of matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMP) in humans. Nine volunteers [5 men and 4 women, mean age 23 (SD...... 4) yr] each performed a bout of 100 maximum voluntary eccentric contractions of the knee extensors. Muscle biopsies were taken before exercise and on days 4 and 22 afterward. Image analysis of stained tissue sections was used to quantify endomysial collagen staining intensity. Maximum voluntary...... contractile force declined by 39 +/- 23% (mean +/- SD) on day 2 postexercise and recovered thereafter. Serum creatine kinase activity peaked on day 4 postexercise (P Collagen type IV staining intensity increased significantly on day 22 postexercise to 126 +/- 29% (mean +/- SD) of preexercise values...

  11. 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...

  12. Structural changes during contraction in vertebrate skeletal muscle as studied by time-resolved X-ray diffraction technique

    International Nuclear Information System (INIS)

    Sugi, H.; Tanaka, H.; Kobayashi, T.; Iwamoto, H.; Wakabayashi, K.; Hamanaka, T.; Mitsui, T.; Amemiya, Y.

    1986-01-01

    To obtain information about the structural changes in vertebrate skeletal muscle during contraction, time-resolved X-ray diffraction studies were performed on the intensity changes of the 59 A and 51 A actin layer lines from bullfrog sartorius muscle during the isometric force development, and the intensity changes of the 143 A and 215 A myosin meridional reflections and of the 1,0 and 1,1 equatorial reflections when isometrically contracting muscle was subjected to sinusoidal length changes (1%, 5-10Hz) with the following results. The integrated intensities of the 59 A and 51 A actin layer lines increased during the force development by 30-50% for the 59 A reflection, and by about 70% for the 51 A reflection compard to their respective resting values. These intensity changes were greater than those taking place during the transition from rest to rigor state, and observed to precede the intensity changes of the 429 A myosin off-meridional reflection and of equatorial reflections. When sinusoidal length changes were applied to the muscle generating steady isometric force, the resulting periodic intensity changes in the 1,0 and 1,1 equatorial reflections were in phase and in antiphase with the length changes, respectively. On the other hand, the 143 A myosin reflection exhibited a characteristic periodic change; its intensity reached a maximum at each boundary between the stretch and release phases of the length changes. These results are discussed in connection with the behavior of the cross-bridges during contraction. (author)

  13. 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....

  14. Contraction intensity and feeding affect collagen and myofibrillar protein synthesis rates differently in human skeletal muscle

    DEFF Research Database (Denmark)

    Holm, Lars; Hall, Gerrit van; Rose, Adam John

    2010-01-01

    Exercise stimulates muscle protein fractional synthesis rate (FSR) but the importance of contractile intensity and whether it interplays with feeding is not understood. This was investigated following two distinct resistance exercise (RE) contraction intensities using an intra-subject design...... to feeding. Further, although functionally linked, the contractile and the supportive matrix structures upregulate their protein synthesis rate quite differently in response to feeding and contractile-activity and -intensity....

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. Simulating the activation, contraction and movement of skeletal muscles using the bidomain model.

    Science.gov (United States)

    Lopez Rincon, A; Cantu, C; Soto, R; Shimoda, S

    2016-08-01

    A simulation of the muscle activation, contraction and movement is here presented. This system was developed based on the Bidomain mathematical model of the electrical propagation in muscles. This study shows an electrical stimuli input to a muscle and how this behave. The comparison between healthy subject and patient with muscle activation impairment is depicted, depending on whether the signal reaches a threshold. A 3D model of a bicep muscle and a forearm bone connected was constructed using OpenGL. This platform could be used for development of controllers for biomechatronic systems in future works. This kind of bioinspired model could be used for a better understanding of the neuromotor system.

  3. 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.

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

    Science.gov (United States)

    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.

  5. 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.

  6. 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.

  7. 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)

  8. 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

  9. 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.

  10. Skeletal muscle fiber type composition and performance during repeated bouts of maximal, concentric contractions

    Science.gov (United States)

    Colliander, E. B.; Dudley, G. A.; Tesch, P. A.

    1988-01-01

    Force output and fatigue and recovery patterns were studied during intermittent short-term exercise. 27 men performed three bouts of 30 maximal unilateral knee extensions on 2 different occasions. Blood flow was maintained or occluded during recovery periods (60 s). Blood flow was restricted by inflating a pneumatic cuff placed around the proximal thigh. Muscle biopsies from vastus lateralis were analyzed for identification of fast twitch (FT) and slow twitch (ST) fibers and relative FT area. Peak torque decreased during each bout of exercise and more when blood flow was restricted during recovery. Initial peak torque (IPT) and average peak torque (APT) decreased over the three exercise bouts. This response was 3 fold greater without than with blood flow during recovery. IPT and APT decreased more in individuals with mainly FT fibers than in those with mainly ST fibers. It is suggested that performance during repeated bouts of maximal concentric contractions differs between individuals with different fiber type composition. Specifically, in high intensity, intermittent exercise with emphasis on anaerobic energy release a high FT composition may not necessarily be advantageous for performance.

  11. The influence of electromagnetic radiation generated by a mobile phone on the skeletal system of rats.

    Science.gov (United States)

    Sieroń-Stołtny, Karolina; Teister, Łukasz; Cieślar, Grzegorz; Sieroń, Dominik; Śliwinski, Zbigniew; Kucharzewski, Marek; Sieroń, Aleksander

    2015-01-01

    The study was focused on the influence of electromagnetic field generated by mobile phone on the skeletal system of rats, assessed by measuring the macrometric parameters of bones, mechanical properties of long bones, calcium and phosphorus content in bones, and the concentration of osteogenesis (osteocalcin) and bone resorption (NTX, pyridinoline) markers in blood serum. The study was carried out on male rats divided into two groups: experimental group subjected to 28-day cycle of exposures in electromagnetic field of 900 MHz frequency generated by mobile phone and a control, sham-exposed one. The mobile phone-generated electromagnetic field did not influence the macrometric parameters of long bones and L4 vertebra, it altered mechanical properties of bones (stress and energy at maximum bending force, stress at fracture), it decreased the content of calcium in long bones and L4 vertebra, and it altered the concentration of osteogenesis and bone resorption markers in rats. On the basis of obtained results, it was concluded that electromagnetic field generated by 900 MHz mobile phone does not have a direct impact on macrometric parameters of bones; however, it alters the processes of bone mineralization and the intensity of bone turnover processes and thus influences the mechanical strength of bones.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. Sustained inhibition of rat myometrial gap junctions and contractions by lindane

    Directory of Open Access Journals (Sweden)

    Grindatti Carmen M

    2003-10-01

    Full Text Available Abstract Background Gap junctions increase in size and abundance coincident with parturition, forming an intercellular communication network that permits the uterus to develop the forceful, coordinated contractions necessary for delivery of the fetus. Lindane, a pesticide used in the human and veterinary treatment of scabies and lice as well as in agricultural applications, inhibits uterine contractions in vitro, inhibits myometrial gap junctions, and has been associated with prolonged gestation length in rats. The aim of the present study was to investigate whether brief exposures to lindane would elicit sustained inhibition of rat uterine contractile activity and myometrial gap junction intercellular communication. Methods To examine effects on uterine contraction, longitudinal uterine strips isolated from late gestation (day 20 rats were exposed to lindane in muscle baths and monitored for changes in spontaneous phasic contractions during and after exposure to lindane. Lucifer yellow dye transfer between myometrial cells in culture was used to monitor gap junction intercellular communication. Results During a 1-h exposure, 10 micro M and 100 micro M lindane decreased peak force and frequency of uterine contraction but 1 micro M lindane did not. After removal of the exposure buffer, contraction force remained significantly depressed in uterine strips exposed to 100 micro M lindane, returning to less than 50% basal levels 5 h after cessation of lindane exposure. In cultured myometrial myocytes, significant sustained inhibition of Lucifer yellow dye transfer was observed 24 h after lindane exposures as brief as 10 min and as low as 0.1 micro M lindane. Conclusion Brief in vitro exposures to lindane have long-term effects on myometrial functions that are necessary for parturition, inhibiting spontaneous phasic contractions in late gestation rat uterus and gap junction intercellular communication in myometrial cell cultures.

  17. A Ca2+-calmodulin-eEF2K-eEF2 signalling cascade, but not AMPK, contributes to the suppression of skeletal muscle protein synthesis during contractions

    DEFF Research Database (Denmark)

    Rose, Adam John; Alsted, Thomas Junker; Jensen, Thomas Elbenhardt

    2009-01-01

    Skeletal muscle protein synthesis rate decreases during contractions but the underlying regulatory mechanisms are poorly understood. It was hypothesised that there would be a coordinated regulation of eukaryotic elongation factor 2 (eEF2) and eukaryotic initiation factor 4E-binding protein 1 (4EBP1......) phosphorylation by signalling cascades downstream of rises in intracellular [Ca(2+)] and decreased energy charge via AMP activated protein kinase (AMPK) in contracting skeletal muscle. When fast-twitch skeletal muscles were contracted ex vivo using different protocols, the suppression of protein synthesis...... correlated more closely with changes in eEF2 rather than 4EBP1 phosphorylation. Using a combination of Ca(2+) release agents and ATPase inhibitors it was shown that the 60-70% suppression of fast-twitch skeletal muscle protein synthesis during contraction was equally distributed between Ca(2+) and energy...

  18. 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.

  19. Intermedin inhibits norepinephrine-induced contraction of rat seminal vesicle

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    P.F. Wong

    2014-09-01

    Conclusion: The results demonstrated that the inhibitory action of IMD on NE-induced seminal vesicle contraction was mediated via the ADM receptor(s and the nitric oxide production pathway, partially by the IMD receptor, but not by the CGRP receptor and the cAMP-PKA pathway.

  20. 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.

  1. 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.

  2. 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

  3. Acetylcholine and choline contents of rat skeletal muscle determined by a radioenzymatic microassay: effects of drugs

    International Nuclear Information System (INIS)

    Consolo, S.

    1986-01-01

    This paper describes a specific, radioenzymatic microassay for measuring picomole quantities of ACh in skeletal muscle. The levels of ACh as well ascholine in the extensor digitorum longus (EDL), soleus and gastrocnemiusmuscles of the rat are reported after focussed microwave irradiation to the hind limb to prevent post-mortem changes in ACh and choline contents. Particular attention was directed to the effect of some drugs potently affecting neuromuscular transmission at the end plate. Preparation of tissue samples, extraction and electrophoresis are described. A 26 ul portion of a second incubation mixture of tritium-acetylcoenzyme A and 14 ul of a partially purified choline acetyltransferase solution were added. A flow sheet giving an overview of he analytical steps involved in the method are shown

  4. 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

  5. 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.

  6. 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

  7. 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.

  8. Upper motor neurone modulation of the structure of the terminal cisternae in rat skeletal muscle fibres.

    Science.gov (United States)

    Dulhunty, A F; Gage, P W; Valois, A A

    1981-12-23

    There are fewer indentations on the flat surfaces of terminal cisternae in soleus (slow-twitch) than in extensor digitorum longus (EDL, fast-twitch) muscle fibres of rats. Following mid-thoracic spinal cord transection, there is an increase in the number of indentations in soleus fibres but no change in EDL fibres. The increase in the numbers of indentations after spinal cord transections is correlated with changes in the contractile and charge movement properties of the soleus fibres so that they resemble normal EDL fibres. The indentations appear to have an important role in excitation-contraction coupling.

  9. Effects of Trigonelline, an Alkaloid Present in Coffee, on Diabetes-Induced Disorders in the Rat Skeletal System.

    Science.gov (United States)

    Folwarczna, Joanna; Janas, Aleksandra; Pytlik, Maria; Cegieła, Urszula; Śliwiński, Leszek; Krivošíková, Zora; Štefíková, Kornélia; Gajdoš, Martin

    2016-03-02

    Diabetes increases bone fracture risk. Trigonelline, an alkaloid with potential antidiabetic activity, is present in considerable amounts in coffee. The aim of the study was to investigate the effects of trigonelline on experimental diabetes-induced disorders in the rat skeletal system. Effects of trigonelline (50 mg/kg p.o. daily for four weeks) were investigated in three-month-old female Wistar rats, which, two weeks before the start of trigonelline administration, received streptozotocin (60 mg/kg i.p.) or streptozotocin after nicotinamide (230 mg/kg i.p.). Serum bone turnover markers, bone mineralization, and mechanical properties were studied. Streptozotocin induced diabetes, with significant worsening of bone mineralization and bone mechanical properties. Streptozotocin after nicotinamide induced slight glycemia increases in first days of experiment only, however worsening of cancellous bone mechanical properties and decreased vertebral bone mineral density (BMD) were demonstrated. Trigonelline decreased bone mineralization and tended to worsen bone mechanical properties in streptozotocin-induced diabetic rats. In nicotinamide/streptozotocin-treated rats, trigonelline significantly increased BMD and tended to improve cancellous bone strength. Trigonelline differentially affected the skeletal system of rats with streptozotocin-induced metabolic disorders, intensifying the osteoporotic changes in streptozotocin-treated rats and favorably affecting bones in the non-hyperglycemic (nicotinamide/streptozotocin-treated) rats. The results indicate that, in certain conditions, trigonelline may damage bone.

  10. Deformation and three-dimensional displacement of fibers in isometrically contracting rat plantaris muscles

    NARCIS (Netherlands)

    Savelberg, Hans H.C.M.; Willems, Paul J.B.; Willems, P.; Baan, Guus C.; Huijing, P.A.J.B.M.

    2001-01-01

    In this study, the deformation of different fibers of the rat m. plantaris during isometric contractions at different muscle lengths was considered. Because the m. plantaris has an obviously inhomogeneous architecture, its fibers on the medial side of the muscle belly are judged to be shorter than

  11. Genomic expression analysis of rat chromosome 4 for skeletal traits at femoral neck.

    Science.gov (United States)

    Alam, Imranul; Sun, Qiwei; Liu, Lixiang; Koller, Daniel L; Liu, Yunlong; Edenberg, Howard J; Econs, Michael J; Foroud, Tatiana; Turner, Charles H

    2008-10-08

    Hip fracture is the most devastating osteoporotic fracture type with significant morbidity and mortality. Several studies in humans and animal models identified chromosomal regions linked to hip size and bone mass. Previously, we identified that the region of 4q21-q41 on rat chromosome (Chr) 4 harbors multiple femoral neck quantitative trait loci (QTLs) in inbred Fischer 344 (F344) and Lewis (LEW) rats. The purpose of this study is to identify the candidate genes for femoral neck structure and density by correlating gene expression in the proximal femur with the femoral neck phenotypes linked to the QTLs on Chr 4. RNA was extracted from proximal femora of 4-wk-old rats from F344 and LEW strains, and two other strains, Copenhagen 2331 and Dark Agouti, were used as a negative control. Microarray analysis was performed using Affymetrix Rat Genome 230 2.0 arrays. A total of 99 genes in the 4q21-q41 region were differentially expressed (P level of the gene in that strain. A total of 18 candidate genes were strongly correlated (r(2) > 0.50) with femoral neck width and prioritized for further analysis. Quantitative PCR analysis confirmed 14 of 18 of the candidate genes. Ingenuity pathway analysis revealed several direct or indirect relationships among the candidate genes related to angiogenesis (VEGF), bone growth (FGF2), bone formation (IGF2 and IGF2BP3), and resorption (TNF). This study provides a shortened list of genetic determinants of skeletal traits at the hip and may lead to novel approaches for prevention and treatment of hip fracture.

  12. 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

  13. Inhibition of xanthine oxidase reduces oxidative stress and improves skeletal muscle function in response to electrically stimulated isometric contractions in aged mice

    Science.gov (United States)

    Ryan, Michael J.; Jackson, Janna R.; Hao, Yanlei; Leonard, Stephen S.; Alway, Stephen E.

    2012-01-01

    Oxidative stress is a putative factor responsible for reducing function and increasing apoptotic signaling in skeletal muscle with aging. This study examined the contribution and functional significance of the xanthine oxidase enzyme as a potential source of oxidant production in aged skeletal muscle during repetitive in situ electrically stimulated isometric contractions. Xanthine oxidase activity was inhibited in young adult and aged mice via a subcutaneously placed time release (2.5 mg/day) allopurinol pellet, 7 days prior to the start of in situ electrically stimulated isometric contractions. Gastrocnemius muscles were electrically activated with 20 maximal contractions for three consecutive days. Xanthine oxidase activity was 65% greater in the gastrocnemius muscle of aged mice compared to young mice. Xanthine oxidase activity also increased after in situ electrically stimulated isometric contractions in muscles from both young (33%) and aged (28%) mice, relative to contralateral non-contracted muscles. Allopurinol attenuated the exercise-induced increase in oxidative stress, but it did not affect the elevated basal levels of oxidative stress that was associated with aging. In addition, inhibition of xanthine oxidase activity decreased caspase 3 activity, but it had no effect on other markers of mitochondrial associated apoptosis. Our results show that compared to control conditions, suppression of xanthine oxidase activity by allopurinol reduced xanthine oxidase activity, H2O2 levels, lipid peroxidation and caspase-3 activity, prevented the in situ electrically stimulated isometric contraction-induced loss of glutathione, prevented the increase of catalase and copper-zinc superoxide dismutase activities, and increased maximal isometric force in the plantar flexor muscles of aged mice after repetitive electrically evoked contractions. PMID:21530649

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. Diverse effects of a 445 nm diode laser on isometric contraction of the rat aorta

    Science.gov (United States)

    Park, Sang Woong; Shin, Kyung Chul; Park, Hyun Ji; Lee, In Wha; Kim, Hyung-Sik; Chung, Soon-Cheol; Kim, Ji-Sun; Jun, Jae-Hoon; Kim, Bokyung; Bae, Young Min

    2015-01-01

    The usefulness of visible lasers in treating vascular diseases is controversial. It is probable that multiple effects of visible lasers on blood vessels and their unclear mechanisms have hampered the usefulness of this therapy. Therefore, elucidating the precise actions and mechanisms of the effects of lasers on blood vessels would provide insight into potential biomedical applications. Here, using organ chamber isometric contraction measurements, western blotting, patch-clamp, and en face immunohistochemistry, we showed that a 445 nm diode laser contracted rat aortic rings, both by activating endothelial nitric oxide synthase and by increasing oxidative stress. In addition to the effects on the endothelium, the laser also directly relaxed and contracted vascular smooth muscle by inhibiting L-type Ca2+ channels and by activating protein tyrosine kinases, respectively. Thus, we conclude that exposure to 445 nm laser might contract and dilate blood vessels in the endothelium and smooth muscle via distinct mechanisms. PMID:26417517

  4. Contraction-induced interleukin-6 gene transcription in skeletal muscle is regulated by c-Jun terminal kinase/activator protein-1.

    Science.gov (United States)

    Whitham, Martin; Chan, M H Stanley; Pal, Martin; Matthews, Vance B; Prelovsek, Oja; Lunke, Sebastian; El-Osta, Assam; Broenneke, Hella; Alber, Jens; Brüning, Jens C; Wunderlich, F Thomas; Lancaster, Graeme I; Febbraio, Mark A

    2012-03-30

    Exercise increases the expression of the prototypical myokine IL-6, but the precise mechanism by which this occurs has yet to be identified. To mimic exercise conditions, C2C12 myotubes were mechanically stimulated via electrical pulse stimulation (EPS). We compared the responses of EPS with the pharmacological Ca(2+) carrier calcimycin (A23187) because contraction induces marked increases in cytosolic Ca(2+) levels or the classical IκB kinase/NFκB inflammatory response elicited by H(2)O(2). We demonstrate that, unlike H(2)O(2)-stimulated increases in IL-6 mRNA, neither calcimycin- nor EPS-induced IL-6 mRNA expression is under the transcriptional control of NFκB. Rather, we show that EPS increased the phosphorylation of JNK and the reporter activity of the downstream transcription factor AP-1. Furthermore, JNK inhibition abolished the EPS-induced increase in IL-6 mRNA and protein expression. Finally, we observed an exercise-induced increase in both JNK phosphorylation and IL-6 mRNA expression in the skeletal muscles of mice after 30 min of treadmill running. Importantly, exercise did not increase IL-6 mRNA expression in skeletal muscle-specific JNK-deficient mice. These data identify a novel contraction-mediated transcriptional regulatory pathway for IL-6 in skeletal muscle.

  5. Relaxant effect of the ethanol extract of Helichrysum plicatum (Asteraceae) on isolated rat ileum contractions.

    Science.gov (United States)

    Bigovic, Dubravka; Brankovic, Suzana; Kitic, Dusanka; Radenkovic, Mirjana; Jankovic, Teodora; Savikin, Katarina; Zivanovic, Slavoljub

    2010-05-10

    Helichrysum plicatum (Turkish Helichrysum) has been used in folk medicine for the treatment of gastric and hepatic disorders. The aim of the present study was to examine the relaxant activity of an extract of H. plicatum flowers on isolated rat ileum. Segments of ileum of rats were suspended in an organ bath. Cumulative concentrations of H. plicatum ethanol extract induced a relaxant effect on spontaneous rat ileum contractions. H. plicatum extract caused a mean contractile response of 81.68 +/- 6.17% (at a dose of 0.01 mg/mL) and 30.08 +/- 9.07% (at a dose of 1 mg/mL). A similar effect was observed with papaverine (0.01-3 microg/mL). H. plicatum extract (0.01-1 mg/mL) relaxed high K+ (80 mM) precontractions, an effect similar to that caused by papaverine (0.01-3 microg/mL). The plant extract (0.03-0.3 mg/mL) also induced a significant depression of the cumulative concentration response curve for acetylcholine (5-1500 nM) (p Helichrysum plicatum flowers on the isolated rat intestine Extract of H. plicatum can inhibit the spontaneous ileum contractions and contractions induced by acetylcholine, histamine, barium and potassium ions.

  6. In vivo determination of steric and electrostatic exclusion of albumin in rat skin and skeletal muscle.

    Science.gov (United States)

    Gyenge, Christina C; Tenstad, Olav; Wiig, Helge

    2003-11-01

    In order to estimate the magnitude of electrostatic exclusion provided by the fixed negative charges of the skin and muscle interstitia of rat in vivo we measured the distribution volumes of two differently charged albumin probes within these tissues. An implanted osmotic pump was used to reach and maintain a steady-state extracellular concentration of a mixture containing two iodine-labelled probes: a charged-modified human serum albumin, cHSA (i.e. a positive probe, isoelectirc point (pI) = 7.6) and a native human serum albumin, HSA (i.e. a normally charged, negative probe, pI = 5.0). Steady-state tissue concentrations were achieved after intravenous infusion of probes for 5-7 days. At the end of this period the animals were nephrectomized and a bolus of 51Cr-EDTA was administered for estimating the extracellular volume. Plasma volumes were measured as 5-min distribution volume of 125I-HSA in separate experiments. The steady-state interstitial fluid concentrations of all probes were determined using nylon wicks implanted postmortem. Calculations of labelled probes were made for interstitial fluid volumes (Vi), extravascular albumin distribution volumes (Vav,a) and relative interstitial excluded volume fractions (Vex,a/Vi). We found that the positive probe is excluded from a significantly smaller fraction of the interstitium. Specifically, the average relative albumin exclusion fractions obtained were: 16% and 26% in skeletal muscle and 30% and 40% in skin, for cHSA and HSA, respectively. On average, the fixed negative charges of the interstitium are responsible for about 40% of the total albumin exclusion in skeletal muscle and 25% in the whole skin tissue and thus, contribute significantly to volume exclusion in these tissues.

  7. Effects of Streptomycin Administration on Increases in Skeletal Muscle Fiber Permeability and Size Following Eccentric Muscle Contractions.

    Science.gov (United States)

    Hayao, Keishi; Tamaki, Hiroyuki; Nakagawa, Kouki; Tamakoshi, Keigo; Takahashi, Hideaki; Yotani, Kengo; Ogita, Futoshi; Yamamoto, Noriaki; Onishi, Hideaki

    2018-06-01

    The purpose of this study was to investigate the preventive effect of streptomycin (Str) administration on changes in membrane permeability and the histomorphological characteristics of damaged muscle fibers following eccentric contraction (ECC ). Eighteen 7-week-old male Fischer 344 rats were randomly assigned to three groups: control (Cont), ECC, and ECC with Str (ECC + Str). The tibialis anterior (TA) muscles in both ECC groups were stimulated electrically and exhibited ECC. Evans blue dye (EBD), a marker of muscle fiber damage associated with increased membrane permeability, was injected 24 hr before TA muscle sampling. The number of EBD-positive fibers, muscle fiber cross-sectional area (CSA), and roundness were determined via histomorphological analysis. The ECC intervention resulted in an increased fraction of EBD-positive fibers, a larger CSA, and decreased roundness. The fraction of EBD-positive fibers was 79% lower in the ECC + Str group than in the ECC group. However, there was no difference in the CSA and roundness of the EBD-positive fibers between the two ECC groups. These results suggest that Str administration can reduce the number of myofibers that increase membrane permeability following ECC, but does not ameliorate the extent of fiber swelling in extant EBD-positive fibers. Anat Rec, 301:1096-1102, 2018. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

  8. 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

  9. 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....

  10. 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.

  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

    Directory of Open Access Journals (Sweden)

    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. 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)

  14. Altered elementary calcium release events and enhanced calcium release by thymol in rat skeletal muscle.

    Science.gov (United States)

    Szentesi, Péter; Szappanos, Henrietta; Szegedi, Csaba; Gönczi, Monika; Jona, István; Cseri, Julianna; Kovács, László; Csernoch, László

    2004-03-01

    The effects of thymol on steps of excitation-contraction coupling were studied on fast-twitch muscles of rodents. Thymol was found to increase the depolarization-induced release of calcium from the sarcoplasmic reticulum, which could not be attributed to a decreased calcium-dependent inactivation of calcium release channels/ryanodine receptors or altered intramembrane charge movement, but rather to a more efficient coupling of depolarization to channel opening. Thymol increased ryanodine binding to heavy sarcoplasmic reticulum vesicles, with a half-activating concentration of 144 micro M and a Hill coefficient of 1.89, and the open probability of the isolated and reconstituted ryanodine receptors, from 0.09 +/- 0.03 to 0.22 +/- 0.04 at 30 micro M. At higher concentrations the drug induced long-lasting open events on a full conducting state. Elementary calcium release events imaged using laser scanning confocal microscopy in the line-scan mode were reduced in size, 0.92 +/- 0.01 vs. 0.70 +/- 0.01, but increased in duration, 56 +/- 1 vs. 79 +/- 1 ms, by 30 micro M thymol, with an increase in the relative proportion of lone embers. Higher concentrations favored long events, resembling embers in control, with duration often exceeding 500 ms. These findings provide direct experimental evidence that the opening of a single release channel will generate an ember, rather than a spark, in mammalian skeletal muscle.

  15. Proteomic and carbonylation profile analysis of rat skeletal muscles following acute swimming exercise.

    Directory of Open Access Journals (Sweden)

    Francesca Magherini

    Full Text Available Previous studies by us and other groups characterized protein expression variation following long-term moderate training, whereas the effects of single bursts of exercise are less known. Making use of a proteomic approach, we investigated the effects of acute swimming exercise (ASE on protein expression and carbonylation patterns in two hind limb muscles: the Extensor Digitorum Longus (EDL and the Soleus, mostly composed of fast-twitch and slow-twitch fibres, respectively. Carbonylation is one of the most common oxidative modifications of proteins and a marker of oxidative stress. In fact, several studies suggest that physical activity and the consequent increase in oxygen consumption can lead to increase in reactive oxygen and nitrogen species (RONS production, hence the interest in examining the impact of RONS on skeletal muscle proteins following ASE. Results indicate that protein expression is unaffected by ASE in both muscle types. Unexpectedly, the protein carbonylation level was reduced following ASE. In particular, the analysis found 31 and 5 spots, in Soleus and EDL muscles respectively, whose carbonylation is reduced after ASE. Lipid peroxidation levels in Soleus were markedly reduced as well. Most of the decarbonylated proteins are involved either in the regulation of muscle contractions or in the regulation of energy metabolism. A number of hypotheses may be advanced to account for such results, which will be addressed in future studies.

  16. 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

  17. Eccentric contractions affect muscle membrane phospholipid fatty acid composition in rats

    DEFF Research Database (Denmark)

    Helge, Jørn Wulff; Therkildsen, K J; Jørgensen, T B

    2001-01-01

    This study investigated if prior eccentric contractions, and thus mechanical strain and muscle damage, exert an effect on the muscle membrane phospholipid fatty acid composition in rats, and whether a possible effect could be attenuated by dietary supplements. Twenty-three rats were randomised...... muscle, was excised from both legs. In the muscles stimulated to contract eccentrically, compared to the control muscles, the proportion of arachidonic acid, C20:4,n-6 (17.7 +/- 0.6; 16.4 +/- 0.4% of total fatty acids, respectively) and docosapentanoeic acid, C22:5,n-3 (2.9 +/- 0.1 and 2.7 +/- 0.......1% of total fatty acids, respectively) was uniformly higher across groups (P fatty acids) compared to the control leg (38.2 +/- 0...

  18. 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

  19. Activity of Ca(2+,Mg(2+-ATPase of sarcoplasmic reticulum and contraction strength of the frog skeletal muscles under the effect of organophosphorus insecticides

    Directory of Open Access Journals (Sweden)

    D. M. Nozdrenko

    2015-08-01

    Full Text Available The results of an experimental study of organo­phosphorus insecticides, including pirimiphosmethyl, diazinon and chlorpyrifos caused a decline of the contraction properties in m. tibialis anterior fiber bundles of Rana temporaria, as well as sarcoplasmic reticulum Ca2+,Mg2+-ATPase enzymatic activity reduction are outlined in this paper. Concentration-dependent strengths response diminishing in isolated skeletal muscle fiber bundles as a result of non-cholinergic influence of organophosphorus insecticides were found. A decrease of Ca2+,Mg2+-ATPase enzymatic activity in sarcoplasmic reticulum was observed after administration of each insecticide. The most significant inhibition of this enzyme was observed when using chlorpyrifos.

  20. [ACTIVITY OF Ca2+,Mg(2+)-ATPase OF SARCOPLASMIC RETICULUM AND CONTRACTION STRENGTH OF THE FROG SKELETAL MUSCLES UNDER THE EFFECT OF ORGANOPHOSPHORUS INSECTICIDES].

    Science.gov (United States)

    Nozdrenko, D M; Korchinska, L V; Soroca, V M

    2015-01-01

    The results of an experimental study of organophosphorus insecticides, including pirimiphosmethyl, diazinon and chlorpyrifos caused a decline of the contraction properties in m. tibialis anterior fiber bundles of Rana temporaria, as well as sarcoplasmic reticulum Ca2+, Mg(2+)-ATPase enzymatic activity reduction are outlined in this paper. Concentration-dependent strengths response diminishing in isolated skeletal muscle fiber bundles as a result of non-cholinergic influence of organophosphorus insecticides were found. A decrease of Ca2+, Mg(2+)-ATPase enzymatic activity in sarcoplasmic reticulum was observed after administration of each insecticide. The most significant inhibition of this enzyme was observed when using chlorpyrifos.

  1. Expression of the skeletal calsequestrin isoform in normal and regenerated skeletal muscles and in the hearts of rats with altered thyroid status

    Czech Academy of Sciences Publication Activity Database

    Soukup, Tomáš; Sulimenko, Vadym; Marková, Vladimíra; Kopecká, Kateřina; Zachařová, Gisela; Paleček, Jiří

    2012-01-01

    Roč. 61, č. 6 (2012), s. 575-586 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GA304/08/0256; GA ČR(CZ) GA305/09/1228; GA ČR(CZ) GBP304/12/G069 Grant - others:EC(XE) Myores 511978 Institutional research plan: CEZ:AV0Z50110509; CEZ:AV0Z50520701 Institutional support: RVO:67985823 ; RVO:68378050 Keywords : skeletal calsequestrin * calcium and muscle contraction * thyroid hormones * western blot and qRT-PCR analysis * muscle transplantation * fast and slow muscle fibers Subject RIV: EA - Cell Biology Impact factor: 1.531, year: 2012

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

    Directory of Open Access Journals (Sweden)

    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.

  3. Effects of fetal hypothyroidism on uterine smooth muscle contraction and structure of offspring rats.

    Science.gov (United States)

    Bagheripuor, Fatemeh; Ghanbari, Mahboubeh; Piryaei, Abbas; Ghasemi, Asghar

    2018-05-01

    What is the central question of this study? Does fetal hypothyroidism in rats alter uterine contractions and structure in the adult offspring? What is the main finding and its importance? Our study indicated that maternal hypothyroidism during pregnancy increased gestational length and decreased litter size. In addition, maternal hypothyroidism caused delayed puberty onset, irregular uterine contractions and histological changes in the uterus in the female offspring. This model might contribute to a better understanding of the cellular and molecular mechanisms involved in uterine contractions in fetal hypothyroidism, studies which are not possible in humans, and might help to establish therapeutic methods for these disorders observed in uterine contractions. Thyroid hormones play an essential role in fetal growth. Hypothyroidism impairs reproductive function in both humans and animals. The aim of this study was to assess the effects of fetal hypothyroidism on uterine smooth muscle contraction and structure in the adult offspring. The control group of female Wistar rats consumed tap water, whereas the hypothyroid group received water containing 0.025% of 6-propyl-2-thiouracial throughout gestation from mating until delivery. Isometric contractility and histological changes in uterine tissue were evaluated in the adult female offspring. We tested the effects of carbachol (10 -10 -10 -3  m) and oxytocin (10 -13 -10 -8  m) on uterine smooth muscle contraction in the fetal hypothyroid (FH) and control groups. Compared with control uteri, carbachol induced contractions with lower amplitude in the FH group (area under the curve: 1820.0 ± 250.0 versus 1370.0 ± 125.0 a.u., control versus FH group, respectively, P muscle layer and the cross-sectional area of the uterus were also significantly lower in the FH group. Gestational length was longer and litter size smaller in FH rats compared with control animals; FH offspring also had delayed puberty. In conclusion

  4. "INHIBITORY EFFECT OF ALUMINIUM ON KCL AND PHENYLEPHRINE INDUCED CONTRACTION IN ISOLATED RAT AORTA"

    Directory of Open Access Journals (Sweden)

    T. Mashhoodi

    2004-10-01

    Full Text Available It has been shown in some investigations that cardiovascular events are the main causes of death in hemodialysis patients. The exact etiology is unknown but some of the articles have reported a relation between aluminium ions in the dialysis solution and cardiovascular disorders. To determine the probable effect of aluminium on vasculature function, in vitro effects of aluminium ion on vasoconstriction induced by KCl (30 mM or phenylephrine (10 µM were investigated using isolated rat aorta. AlCl3 (1-4 mM decreased both KCl and phenylephrine induced contractions in a dose dependent manner (P<0.01. Complete inhibition of the contractions occurred using the higher doses of aluminium. Results of this study suggest that because of inhibitory effects of aluminium on vascular contractions, the probable cardiovascular dysfunction must be considered in aluminium intoxication.

  5. 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.

  6. 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

  7. Regulation of the sodium-potassium pump in cultured rat skeletal myotubes by intracellular sodium ions

    International Nuclear Information System (INIS)

    Brodie, C.; Sampson, S.R.

    1989-01-01

    The properties of the Na-K pump and some of the factors controlling its amount and function were studied in rat myotubes in culture. The number of Na-K pump sites was quantified by measuring the amount of [ 3 H]ouabain bound to whole-cell preparations. Activity of the pump was determined by measurement of ouabain-sensitive 86 Rb-uptake and component of membrane potential. Chronic treatment of myotubes with tetrodotoxin (TTX), which lowers [Na]i, decreased the number of Na-K pumps, the ouabain-sensitive 86Rb uptake, and the size of the electrogenic pump component of Em. In contrast, chronic treatment with either ouabain or veratridine, which increases [Na+]i, resulted in an elevated level of Na-K pump sites. This effect was blocked by inhibitors of protein synthesis. Neither rates of degradation nor affinity of pump sites in cells treated with TTX, veratridine, or ouabain differred from those in control cells. The number and activity of Na-K pump sites were unaffected by chronic elevation in [Ca]i or chronic depolarization. We conclude that alterations in the level in intracellular Na ions play the major role in regulation of Na-K pump synthesis in cultured mammalian skeletal muscle

  8. 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.

  9. Is abdominal wall contraction important for normal voiding in the female rat?

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    Boone Timothy B

    2007-03-01

    Full Text Available Abstract Background Normal voiding behavior in urethane-anesthetized rats includes contraction of the abdominal wall striated muscle, similar to the visceromotor response (VMR to noxious bladder distension. Normal rat voiding requires pulsatile release of urine from a pressurized bladder. The abdominal wall contraction accompanying urine flow may provide a necessary pressure increment for normal efficient pulsatile voiding. This study aimed to evaluate the occurrence and necessity of the voiding-associated abdominal wall activity in urethane-anesthetized female rats Methods A free-voiding model was designed to allow assessment of abdominal wall activity during voiding resulting from physiologic bladder filling, in the absence of bladder or urethral instrumentation. Physiologic diuresis was promoted by rapid intravascular hydration. Intercontraction interval (ICI, voided volumes and EMG activity of the rectus abdominis were quantified. The contribution of abdominal wall contraction to voiding was eliminated in a second group of rats by injecting botulinum-A (BTX, 5 U into each rectus abdominis to induce local paralysis. Uroflow parameters were compared between intact free-voiding and BTX-prepared animals. Results Abdominal wall response is present in free voiding. BTX preparation eliminated the voiding-associated EMG activity. Average per-void volume decreased from 1.8 ml to 1.1 ml (p Conclusion The voiding-associated abdominal wall response is a necessary component of normal voiding in urethane anesthetized female rats. As the proximal urethra may be the origin of the afferent signaling which results in the abdominal wall response, the importance of the bladder pressure increment due to this response may be in maintaining a normal duration intermittent pulsatile high frequency oscillatory (IPHFO/flow phase and thus efficient voiding. We propose the term Voiding-associated Abdominal Response (VAR for the physiologic voiding-associated EMG

  10. 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....

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

    Science.gov (United States)

    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

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

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    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.

  13. Influence of exercise contraction mode and protein supplementation on human skeletal muscle satellite cell content and muscle fiber growth

    DEFF Research Database (Denmark)

    Farup, Jean; Rahbek, Stine Klejs; Riis, Simon

    2014-01-01

    -specific association between emergence of satellite cells (SCs), muscle growth, and remodeling in response to 12 wk unilateral resistance training performed as eccentric (Ecc) or concentric (Conc) resistance training ± whey protein (Whey, 19.5 g protein + 19.5 g glucose) or placebo (Placebo, 39 g glucose......Skeletal muscle satellite cells (SCs) are involved in remodeling and hypertrophy processes of skeletal muscle. However, little knowledge exists on extrinsic factors that influence the content of SCs in skeletal muscle. In a comparative human study, we investigated the muscle fiber type......) supplementation. Muscle biopsies (vastus lateralis) were analyzed for fiber type-specific SCs, myonuclei, and fiber cross-sectional area (CSA). Following training, SCs increased with Conc in both type I and type II fibers (P

  14. Differential regulation of PGC-1α expression in rat liver and skeletal muscle in response to voluntary running

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    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.

  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. 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.

  17. Enhanced Glycogen Storage of a Subcellular Hot Spot in Human Skeletal Muscle during Early Recovery from Eccentric Contractions

    DEFF Research Database (Denmark)

    Nielsen, Joachim; Farup, Jean; Rahbek, Stine Klejs

    2015-01-01

    Unaccustomed eccentric exercise is accompanied by muscle damage and impaired glucose uptake and glycogen synthesis during subsequent recovery. Recently, it was shown that the role and regulation of glycogen in skeletal muscle are dependent on its subcellular localization, and that glycogen synthe...

  18. Impact of electromagnetic radiation exposure during pregnancy on embryonic skeletal development in rats

    Directory of Open Access Journals (Sweden)

    Ali SAEED H Alchalabi

    2017-03-01

    Full Text Available Objective: To evaluate the teratogenic effect of mobile phone radiation exposure during pregnancy on embryonic skeletal development at the common used mobile phone frequency in our environment. Methods: Sixty female Sprague-Dawley rats were distributed into three experiment groups; control and two exposed groups (1 h/day, 2 h/day exposure groups (n=20/ each group and exposed to whole body radiation during gestation period from day 1- day 20. Electromagnetic radiofrequency signal generator was used to generate 1 800 MHz GSM-like signals at specific absorption rate value 0.974 W/kg. Animals were exposed during experiment in an especial designed Plexiglas box (60 cm × 40 cm × 30 cm. At the end of exposure duration at day 20 of pregnancy animals were sacrificed and foetuses were removed, washed with normal saline and processed to Alizarin red and Alcian blue stain. Skeleton specimens were examined under a stereo microscope and skeleton's snaps were being carefully captured by built in camera fixed on the stereo microscope. Results: Intrauterine exposure to electromagnetic radiation lead to variation in degree of ossification, mineralization, formation of certain parts of the skeleton majorly in head and lesser in other parts. Deformity and absence of formation of certain bones in the head, ribs, and coccygeal vertebrae were recorded in skeleton of foetuses from exposed dams compare to control group. Conclusions: The electromagnetic radiation exposure during pregnancy alter the processes of bone mineralization and the intensity of bone turnover processes, and thus impact embryonic skeleton formation and development directly.

  19. Changes in contractile activation characteristics of rat fast and slow skeletal muscle fibres during regeneration.

    Science.gov (United States)

    Gregorevic, Paul; Plant, David R; Stupka, Nicole; Lynch, Gordon S

    2004-07-15

    Damaged skeletal muscle fibres are replaced with new contractile units via muscle regeneration. Regenerating muscle fibres synthesize functionally distinct isoforms of contractile and regulatory proteins but little is known of their functional properties during the regeneration process. An advantage of utilizing single muscle fibre preparations is that assessment of their function is based on the overall characteristics of the contractile apparatus and regulatory system and as such, these preparations are sensitive in revealing not only coarse, but also subtle functional differences between muscle fibres. We examined the Ca(2+)- and Sr(2+)-activated contractile characteristics of permeabilized fibres from rat fast-twitch (extensor digitorum longus) and slow-twitch (soleus) muscles at 7, 14 and 21 days following myotoxic injury, to test the hypothesis that fibres from regenerating fast and slow muscles have different functional characteristics to fibres from uninjured muscles. Regenerating muscle fibres had approximately 10% of the maximal force producing capacity (P(o)) of control (uninjured) fibres, and an altered sensitivity to Ca(2+) and Sr(2+) at 7 days post-injury. Increased force production and a shift in Ca(2+) sensitivity consistent with fibre maturation were observed during regeneration such that P(o) was restored to 36-45% of that in control fibres by 21 days, and sensitivity to Ca(2+) and Sr(2+) was similar to that of control (uninjured) fibres. The findings support the hypothesis that regenerating muscle fibres have different contractile activation characteristics compared with mature fibres, and that they adopt properties of mature fast- or slow-twitch muscle fibres in a progressive manner as the regeneration process is completed.

  20. 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.

  1. Calcium currents in a fast-twitch skeletal muscle of the rat.

    Science.gov (United States)

    Donaldson, P L; Beam, K G

    1983-10-01

    obscured by nonlinear charge movement. Nonetheless, at physiological temperatures, the rate of calcium channel activation in rat skeletal muscle is about five times faster than activation of calcium channels in frog muscle. This pathway may be an important source of calcium entry in mammalian muscle.

  2. 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.

  3. 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)

  4. 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.

  5. Impaired sarcoplasmic reticulum Ca(2+) release rate after fatiguing stimulation in rat skeletal muscle

    DEFF Research Database (Denmark)

    Ørtenblad, Niels; Sjøgaard, G; Madsen, Klavs

    2000-01-01

    during the first 0.5-1 h the metabolic state recovered to resting levels, and a slow phase from 1-3 h characterized by a rather slow recovery of the mechanical properties. The recovery of SR Ca(2+) release rate was closely correlated to +dF/dt during the slow phase of recovery (r(2) = 0.51; P ... to 66% that persisted for 1 h, followed by a gradual recovery to 87% of prefatigue release rate at 3 h recovery. Tetanic force and rate of force development (+dF/dt) and relaxation (-dF/dt) were depressed by approximately 80% after stimulation. Recovery occurred in two phases: an initial phase, in which......The purpose of the study was to characterize the sarcoplasmic reticulum (SR) function and contractile properties before and during recovery from fatigue in the rat extensor digitorum longus muscle. Fatiguing contractions (60 Hz, 150 ms/s for 4 min) induced a reduction of the SR Ca(2+) release rate...

  6. Expression of Dihydropyridine and Ryanodine Receptors in Type IIA Fibers of Rat Skeletal Muscle

    International Nuclear Information System (INIS)

    Anttila, Katja; Mänttäri, Satu; Järvilehto, Matti

    2007-01-01

    In this study, the fiber type specificity of dihydropyridine receptors (DHPRs) and ryanodine receptors (RyRs) in different rat limb muscles was investigated. Western blot and histochemical analyses provided for the first time evidence that the expression of both receptors correlates to a specific myosin heavy chain (MHC) composition. We observed a significant (p=0.01) correlation between DHP as well as Ry receptor density and the expression of MHC IIa (correlation factor r=0.674 and r=0.645, respectively) in one slow-twitch, postural muscle (m. soleus), one mixed, fast-twitch muscle (m. gastrocnemius) and two fast-twitch muscles (m. rectus femoris, m. extensor digitorum longus). The highest DHP and Ry receptor density was found in the white part of m. rectus femoris (0.058±0.0060 and 0.057±0.0158 ODu, respectively). As expected, the highest relative percentage of MHC IIa was also found in the white part of m. rectus femoris (70.0±7.77%). Furthermore, histochemical experiments revealed that the IIA fibers stained most strongly for the fluorophore-conjugated receptor blockers. Our data clearly suggest that the expression of DHPRs and RyRs follows a fiber type-specific pattern, indicating an important role for these proteins in the maintenance of an effective Ca 2+ cycle in the fast contracting fiber type IIA

  7. 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

  8. 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.)

  9. Eccentric Contraction-Induced Muscle Injury: Reproducible, Quantitative, Physiological Models to Impair Skeletal Muscle's Capacity to Generate Force.

    Science.gov (United States)

    Call, Jarrod A; Lowe, Dawn A

    2016-01-01

    In order to investigate the molecular and cellular mechanisms of muscle regeneration an experimental injury model is required. Advantages of eccentric contraction-induced injury are that it is a controllable, reproducible, and physiologically relevant model to cause muscle injury, with injury being defined as a loss of force generating capacity. While eccentric contractions can be incorporated into conscious animal study designs such as downhill treadmill running, electrophysiological approaches to elicit eccentric contractions and examine muscle contractility, for example before and after the injurious eccentric contractions, allows researchers to circumvent common issues in determining muscle function in a conscious animal (e.g., unwillingness to participate). Herein, we describe in vitro and in vivo methods that are reliable, repeatable, and truly maximal because the muscle contractions are evoked in a controlled, quantifiable manner independent of subject motivation. Both methods can be used to initiate eccentric contraction-induced injury and are suitable for monitoring functional muscle regeneration hours to days to weeks post-injury.

  10. 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.

  11. 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.

  12. α(1) adrenergic receptor agonist, phenylephrine, actively contracts early rat rib fracture callus ex vivo.

    Science.gov (United States)

    McDonald, Stuart J; Dooley, Philip C; McDonald, Aaron C; Djouma, Elvan; Schuijers, Johannes A; Ward, Alex R; Grills, Brian L

    2011-05-01

    Early, soft fracture callus that links fracture ends together is smooth muscle-like in nature. We aimed to determine if early fracture callus could be induced to contract and relax ex vivo by similar pathways to smooth muscle, that is, contraction via α(1) adrenergic receptor (α(1) AR) activation with phenylephrine (PE) and relaxation via β(2) adrenergic receptor (β(2) AR) stimulation with terbutaline. A sensitive force transducer quantified 7 day rat rib fracture callus responses in modified Krebs-Henseliet (KH) solutions. Unfractured ribs along with 7, 14, and 21 day fracture calluses were analyzed for both α(1) AR and β(2) AR gene expression using qPCR, whilst 7 day fracture callus was examined via immunohistochemistry for both α(1) AR and β(2) AR- immunoreactivity. In 7 day callus, PE (10(-6)  M) significantly induced an increase in force that was greater than passive force generated in calcium-free KH (n = 8, mean 51% increase, 95% CI: 26-76%). PE-induced contractions in calluses were attenuated by the α(1) AR antagonist, prazosin (10(-6)  M; n = 7, mean 5% increase, 95% CI: 2-11%). Terbutaline did not relax callus. Gene expression of α(1) ARs was constant throughout fracture healing; however, β(2) AR expression was down-regulated at 7 days compared to unfractured rib (p contract. We propose that increased concentrations of α(1) AR agonists such as noradrenaline may tonically contract callus in vivo to promote osteogenesis. Copyright © 2010 Orthopaedic Research Society.

  13. 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, ...

  14. 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.

  15. Model of excitation-contraction coupling of rat neonatal ventricular myocytes.

    Science.gov (United States)

    Korhonen, Topi; Hänninen, Sandra L; Tavi, Pasi

    2009-02-01

    The neonatal rat ventricular myocyte culture is one of the most popular experimental cardiac cell models. To our knowledge, the excitation-contraction coupling (ECC) of these cells, i.e., the process linking the electrical activity to the cytosolic Ca2+ transient and contraction, has not been previously analyzed, nor has it been presented as a complete system in detail. Neonatal cardiomyocytes are in the postnatal developmental stage, and therefore, the features of their ECC differ vastly from those of adult ventricular myocytes. We present the first complete analysis of ECC in these cells by characterizing experimentally the action potential and calcium signaling and developing the first mathematical model of ECC in neonatal cardiomyocytes that we know of. We show that in comparison to adult cardiomyocytes, neonatal cardiomyocytes have long action potentials, heterogeneous cytosolic Ca2+ signals, weaker sarcoplasmic reticulum Ca2+ handling, and stronger sarcolemmal Ca2+ handling, with a significant contribution by the Na+/Ca2+ exchanger. The developed model reproduces faithfully the ECC of rat neonatal cardiomyocytes with a novel description of spatial cytosolic [Ca2+] signals. Simulations also demonstrate how an increase in the cell size (hypertrophy) affects the ECC in neonatal cardiomyocytes. This model of ECC in developing cardiomyocytes provides a platform for developing future models of cardiomyocytes at different developmental stages.

  16. Effect of stimulation intensity and botulinum toxin isoform on rat bladder strip contractions.

    Science.gov (United States)

    Smith, Christopher P; Boone, Timothy B; de Groat, William C; Chancellor, Michael B; Somogyi, George T

    2003-07-15

    The present experiments compared the inhibitory effects of botulinum toxin A (BoNT-A) and botulinum toxin D (BoNT-D) on neurally evoked contractions of rat bladder strips. We examined the effect of fatigue (trains of 100 shocks at 20Hz every 20s for 10min) followed by non-fatigue stimulation (trains of 100 shocks at 20Hz every 100s for 20min) on the onset of effect and potency of the two toxins. For non-fatigue experiments, strips were untreated (n=4); or incubated with 1.36nM BoNT-A (n=4). During fatigue experiments, strips were untreated (n=5); or treated with either 1.36nM BoNT-A (n=6) or 0.8nM BoNT-D (n=6). In non-fatigue experiments, BoNT-A produced significant decreases in contractile area after 1h of stimulation compared to untreated strips (PD bladder strips, were statistically significant (PD-treated strips, as a significant reduction (PD) and untreated bladder strips responded similarly to atropine, suggesting that the effects of BoNT result from inhibition of both acetylcholine and ATP release. Our results demonstrate that BoNT-D may be a more effective agent to inhibit transmitter release from autonomic nerves of the rat lower urinary tract. Moreover, in our hands, non-fatigue stimulation is as effective as fatigue stimulation in inhibiting bladder strip contractions.

  17. 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.

  18. Mast cell concentration and skin wound contraction in rats treated with Brazilian pepper essential oil (Schinus terebinthifolius Raddi).

    Science.gov (United States)

    Estevão, Lígia Reis Moura; Medeiros, Juliana Pinto de; Simões, Ricardo Santos; Arantes, Rosa Maria Esteves; Rachid, Milene Alvarenga; Silva, Regildo Márcio Gonçalves da; Mendonça, Fábio de Souza; Evêncio-Neto, Joaquim

    2015-04-01

    To evaluate wound contraction and the concentration of mast cells in skin wounds treated with 5% BPT essential oil-based ointment in rats. Twenty rats, male, of adult age, were submitted to skin surgery on the right (RA) and left antimeres (LA) of the thoracic region. They were divided into two groups: control (RA - wounds receiving daily topical application of vaseline and lanolin) and treated (LA - wounds treated daily with the topical ointment). The skin region with wounds were collected at days 4, 7, 14 and 21 after surgery. Those were fixed in 10% formaldehyde and later processed for paraffin embedding. Sections were obtained and stained by H.E for histopathology analysis. The degree of epithelial contraction was measured and mast cell concentration were also evaluated. The treated group showed higher mast cell concentrations (poil increases mast cell concentration and promotes skin wound contraction in rats.

  19. 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.

  20. The Role of Lumbar Sympathetic Nerves in Regulation of Blood Flow to Skeletal Muscle during Anaphylactic Hypotension in Anesthetized Rats.

    Directory of Open Access Journals (Sweden)

    Jie Song

    Full Text Available During hypovolemic shock, skeletal muscle blood flow could be redistributed to vital organs via vasoconstriction in part evoked by activation of the innervating sympathetic nerve activity. However, it is not well known whether this mechanism operates during anaphylactic shock. We determined the femoral artery blood flow (FBF and lumbar sympathetic nerve activity (LSNA mainly regulating the hindquater muscle blood flow during anaphylactic hypotension in anesthetized rats. Anesthetized Sprague-Dawley rats were randomly allocated to the following groups (n = 7/group: (1 non-sensitized, (2 anaphylaxis, (3 anaphylaxis-lumbar sympathectomy (LS and (4 anaphylaxis-sinoaortic denervation (SAD groups. Anaphylaxis was induced by an intravenous injection of the ovalbumin antigen to the sensitized rats. The systemic arterial pressure (SAP, heart rate (HR, central venous pressure (CVP, FBF and LSNA were continuously measured. In the anaphylaxis group, LSNA and HR increased, while SAP and FBF decreased after antigen injection. In the anaphylaxis-SAD group, LSNA did not significantly change during the early phase, but the responses of SAP and FBF were similar to those in the anaphylaxis group. In the anaphylaxis-LS group, both FBF and SAP decreased similarly to the anaphylaxis group during anaphylactic hypotension. These results indicated that LSNA increased via baroreceptor reflex, but this sympathoexcitation or LS did not affect antigen-induced decreases in FBF or SAP. Lumbar sympathetic nerves are not involved in regulation of the blood flow to the hindlimb or systemic blood pressure during anaphylactic hypotension in anesthetized rats.

  1. The effects of tetracaine on charge movement in fast twitch rat skeletal muscle fibres.

    Science.gov (United States)

    Hollingworth, S; Marshall, M W; Robson, E

    1990-02-01

    1. The effects of tetracaine, a local anaesthetic that inhibits muscle contraction, on membrane potential and intramembrane charge movements were investigated in fast twitch rat muscle fibres (extensor digitorum longus). 2. The resting membrane potentials of surface fibres from muscles bathed in isotonic Ringer solution containing 2 mM-tetracaine were well maintained, but higher concentrations of tetracaine caused a time-dependent fall of potential. Muscle fibres bathed in hypertonic solutions containing 2 mM-tetracaine were rapidly depolarized. In both isotonic and hypertonic solutions, the depolarizing effect of tetracaine could not be reversed. 3. Charge movement measurements were made using the middle-of-the-fibre voltage clamp technique. The voltage dependence of charge movements measured in cold isotonic solutions was well fitted by a Boltzmann distribution (Q(V) = Qmax/(1 + exp(-(V-V)/k] where Qmax = 37.3 +/- 2.8 nC muF-1, V = -17.9 +/- 1.2 mV and k = 12.6 +/- 0.8 mV (n = 6, 2 degrees C; means +/- S.E. of means). Similar values were obtained when 2 mM-tetracaine was added to the isotonic bathing fluid (Qmax = 40.6 +/- 2.3 nC microF-1, V = -14.1 +/- 1.3 mV, k = 15.3 +/- 0.8 mV; n = 8, 2 degrees C). 4. Charge movements measured around mechanical threshold in muscle fibres bathed in hypertonic solutions were reduced when 2 mM-tetracaine was added to the bathing fluid. The tetracaine-sensitive component of charge was well fitted with an unconstrained Boltzmann distribution which gave: Qmax = 7.5 nC microF-1, V = -46.5 mV, k = 5.5 mV. The e-fold rise of the foot of the curve was 9.3 mV.

  2. Effects of thyroid hormone on Na+-K+ transport in resting and stimulated rat skeletal muscle

    International Nuclear Information System (INIS)

    Everts, M.E.; Clausen, T.

    1988-01-01

    The effects of hypothyroidism and 3,5,3'-triiodothyronine (T 3 ) treatment on passive Na + -K + fluxes and Na + -K + pump concentration were investigated in isolated rat muscle. Within 12 h after a single dose of T 3 (20 μg/100 g body wt), K + efflux had increased by 21% in soleus and by 20% in extensor digitorum longus muscle. In the presence of ouabain, even larger effects were observed. These changes were associated with a 12% rise in amiloride-suppressible Na + influx but no significant increase in [ 3 H]ouabain binding site concentration. After 3 days of T 3 treatment, the stimulating effect on K + efflux and Na + influx in soleus reached a plateau ∼80 and 40% above control levels, respectively, whereas the maximum increase in [ 3 H]ouabain binding site concentration (103%) was only fully developed after 8 days. Hypothyroidism decreased 86 Rb efflux by 30%. The efflux of K + and the influx of Na + per contraction (both ∼7 nmol/g wet wt) as well as the net loss of K + induced by electrical stimulation were unaffected by T 3 treatment. The rise in resting K + efflux after 12-24 h of T 3 treatment could be partly blocked by dantrolene or trifluoroperazine, indicating that an increase in the cytoplasmic Ca 2+ concentration may contribute to the early rise in K + efflux. It is concluded that the early rise in the resting passive leaks of Na + and K + induced by T 3 is a major driving force for Na + -K + pump synthesis

  3. 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.

  4. Characteristics of myogenic response and ankle torque recovery after lengthening contraction-induced rat gastrocnemius injury

    Directory of Open Access Journals (Sweden)

    Song Hongsun

    2012-10-01

    Full Text Available Abstract Background Although muscle dysfunction caused by unfamiliar lengthening contraction is one of most important issues in sports medicine, there is little known about the molecular events on regeneration process. The purpose of this study was to investigate the temporal and spatial expression patterns of myogenin, myoD, pax7, and myostatin after acute lengthening contraction (LC-induced injury in the rat hindlimb. Methods We employed our originally developed device with LC in rat gastrocnemius muscle (n = 24. Male Wistar rats were anesthetized with isoflurane (aspiration rate, 450 ml/min, concentration, 2.0%. The triceps surae muscle of the right hindlimb was then electrically stimulated with forced isokinetic dorsi-flexion (180°/sec and from 0 to 45°. Tissue contents of myoD, myogenin, pax7, myostatin were measured by western blotting and localizations of myoD and pax7 was measured by immunohistochemistry. After measuring isometric tetanic torque, a single bout of LC was performed in vivo. Results The torque was significantly decreased on days 2 and 5 as compared to the pre-treatment value, and recovered by day 7. The content of myoD and pax7 showed significant increases on day 2. Myogenin showed an increase from day 2 to 5. Myostatin on days 5 and 7 were significantly increased. Immunohistochemical analysis showed that myoD-positive/pax7-positive cells increased on day 2, suggesting that activated satellite cells play a role in the destruction and the early recovery phases. Conclusion We, thus, conclude that myogenic events associate with torque recovery after LC-induced injury.

  5. The acute response of pericytes to muscle-damaging eccentric contraction and protein supplementation in human skeletal muscle.

    Science.gov (United States)

    De Lisio, Michael; Farup, Jean; Sukiennik, Richard A; Clevenger, Nicole; Nallabelli, Julian; Nelson, Brett; Ryan, Kelly; Rahbek, Stine K; de Paoli, Frank; Vissing, Kristian; Boppart, Marni D

    2015-10-15

    Skeletal muscle pericytes increase in quantity following eccentric exercise (ECC) and contribute to myofiber repair and adaptation in mice. The purpose of the present investigation was to examine pericyte quantity in response to muscle-damaging ECC and protein supplementation in human skeletal muscle. Male subjects were divided into protein supplement (WHY; n = 12) or isocaloric placebo (CHO; n = 12) groups and completed ECC using an isokinetic dynamometer. Supplements were consumed 3 times/day throughout the experimental time course. Biopsies were collected prior to (PRE) and 3, 24, 48, and 168 h following ECC. Reflective of the damaging protocol, integrin subunits, including α7, β1A, and β1D, increased (3.8-fold, 3.6-fold and 3.9-fold, respectively, P muscle-damaging ECC increases α7β1 integrin content in human muscle, yet pericyte quantity is largely unaltered. Future studies should focus on the capacity for ECC to influence pericyte function, specifically paracrine factor release as a mechanism toward pericyte contribution to repair and adaptation postexercise. Copyright © 2015 the American Physiological Society.

  6. Noninvasive observation of skeletal muscle contraction using near-infrared time-resolved reflectance and diffusing-wave spectroscopy

    Science.gov (United States)

    Belau, Markus; Ninck, Markus; Hering, Gernot; Spinelli, Lorenzo; Contini, Davide; Torricelli, Alessandro; Gisler, Thomas

    2010-09-01

    We introduce a method for noninvasively measuring muscle contraction in vivo, based on near-infrared diffusing-wave spectroscopy (DWS). The method exploits the information about time-dependent shear motions within the contracting muscle that are contained in the temporal autocorrelation function g(1)(τ,t) of the multiply scattered light field measured as a function of lag time, τ, and time after stimulus, t. The analysis of g(1)(τ,t) measured on the human M. biceps brachii during repetitive electrical stimulation, using optical properties measured with time-resolved reflectance spectroscopy, shows that the tissue dynamics giving rise to the speckle fluctuations can be described by a combination of diffusion and shearing. The evolution of the tissue Cauchy strain e(t) shows a strong correlation with the force, indicating that a significant part of the shear observed with DWS is due to muscle contraction. The evolution of the DWS decay time shows quantitative differences between the M. biceps brachii and the M. gastrocnemius, suggesting that DWS allows to discriminate contraction of fast- and slow-twitch muscle fibers.

  7. Interleukin-6 production in contracting human skeletal muscle is influenced by pre-exercise muscle glycogen content

    DEFF Research Database (Denmark)

    Steensberg, A; Febbraio, M A; Osada, T

    2001-01-01

    1. Prolonged exercise results in a progressive decline in glycogen content and a concomitant increase in the release of the cytokine interleukin-6 (IL-6) from contracting muscle. This study tests the hypothesis that the exercise-induced IL-6 release from contracting muscle is linked to the intram......1. Prolonged exercise results in a progressive decline in glycogen content and a concomitant increase in the release of the cytokine interleukin-6 (IL-6) from contracting muscle. This study tests the hypothesis that the exercise-induced IL-6 release from contracting muscle is linked...... to the intramuscular glycogen availability. 2. Seven men performed 5 h of a two-legged knee-extensor exercise, with one leg with normal, and one leg with reduced, muscle glycogen content. Muscle biopsies were obtained before (pre-ex), immediately after (end-ex) and 3 h into recovery (3 h rec) from exercise in both...... legs. In addition, catheters were placed in one femoral artery and both femoral veins and blood was sampled from these catheters prior to exercise and at 1 h intervals during exercise and into recovery. 3. Pre-exercise glycogen content was lower in the glycogen-depleted leg compared with the control...

  8. 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.

  9. 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

  10. 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.

  11. Hyperthyroidism enhances 5-HT-induced contraction of the rat pulmonary artery: role of calcium-activated chloride channel activation.

    Science.gov (United States)

    Oriowo, Mabayoje A; Oommen, Elsie; Khan, Islam

    2011-11-01

    Experimentally-induced hyperthyroidism in rodents is associated with signs and symptoms of pulmonary hypertension. The main objective of the present study was to investigate the effect of thyroxine-induced pulmonary hypertension on the contractile response of the pulmonary artery to 5-HT and the possible underlying signaling pathway. 5-HT concentration-dependently contracted artery segments from control and thyroxine-treated rats with pD(2) values of 5.04 ± 0.19 and 5.34 ± 0.14, respectively. The maximum response was significantly greater in artery segments from thyroxine-treated rats. Neither BW 723C86 (5-HT(2B)-receptor agonist) nor CP 93129 (5-HT(1B)-receptor agonist) contracted ring segments of the pulmonary artery from control and thyroxine-treated rats at concentrations up to 10(-4)M. There was no significant difference in the level of expression of 5-HT(2A)-receptor protein between the two groups. Ketanserin (3 × 10(-8)M) produced a rightward shift of the concentration-response curve to 5-HT in both groups with equal potency (-logK(B) values were 8.1 ± 0.2 and 7.9 ± 0.1 in control and thyroxine-treated rats, respectively). Nifedipine (10(-6)M) inhibited 5-HT-induced contractions in artery segments from control and thyroxine-treated rats and was more effective against 5-HT-induced contraction in artery segments for thyroxine-treated rats. The calcium-activated chloride channel blocker, niflumic acid (10(-4)M) also inhibited 5-HT-induced contractions in artery segments from control and thyroxine-treated rats and was more effective against 5-HT-induced contraction in artery segments for thyroxine-treated rats. It was concluded that hyperthyroidism enhanced 5-HT-induced contractions of the rat pulmonary artery by a mechanism involving increased activity of calcium-activated chloride channels. Copyright © 2011 Elsevier B.V. All rights reserved.

  12. AMPK alpha1 activation is required for stimulation of glucose uptake by twitch contraction, but not by H2O2, in mouse skeletal muscle

    DEFF Research Database (Denmark)

    Jensen, Thomas Elbenhardt; Schjerling, Peter; Viollet, Benoit

    2008-01-01

    into muscle by certain stimuli. In contrast, no clear function has yet been determined for alpha(1) AMPK in skeletal muscle, possibly due to alpha-AMPK isoform signaling redundancy. By applying low-intensity twitch-contraction and H(2)O(2) stimulation to activate alpha(1) AMPK, but not alpha(2) AMPK......, in wildtype and alpha-AMPK transgenic mouse muscles, this study aimed to define conditions where alpha(1) AMPK is required to increase muscle glucose uptake. METHODOLOGY/PRINCIPAL FINDINGS: Following stimulation with H(2)O(2) (3 mM, 20 min) or twitch-contraction (0.1 ms pulse, 2 Hz, 2 min), signaling and 2......-deoxyglucose uptake were measured in incubated soleus muscles from wildtype and muscle-specific kinase-dead AMPK (KD), alpha(1) AMPK knockout or alpha(2) AMPK knockout mice. H(2)O(2) increased the activity of both alpha(1) and alpha(2) AMPK in addition to Akt phosphorylation, and H(2)O(2)-stimulated glucose...

  13. Production of interleukin-6 in contracting human skeletal muscles can account for the exercise-induced increase in plasma interleukin-6

    DEFF Research Database (Denmark)

    Steensberg, A; Van Hall, Gerrit; Osada, T

    2000-01-01

    1. Plasma interleukin (IL)-6 concentration is increased with exercise and it has been demonstrated that contracting muscles can produce IL-The question addressed in the present study was whether the IL-6 production by contracting skeletal muscle is of such a magnitude that it can account for the IL...... and every hour during the exercise. Leg blood flow was measured in parallel by the ultrasound Doppler technique. IL-6 was measured by enzyme-linked immunosorbent assay (ELISA). 3. Arterial plasma concentrations for IL-6 increased 19-fold compared to rest. The a-fv difference for IL-6 over the exercising leg...... followed the same pattern as did the net IL-6 release. Over the resting leg, there was no significant a-fv difference or net IL-6 release. The work was produced by 2.5 kg of active muscle, which means that during the last 2 h of exercise, the median IL-6 production was 6.8 ng min-1 (kg active muscle)-1...

  14. Structural changes of the regulatory proteins bound to the thin filaments in skeletal muscle contraction by X-ray fiber diffraction

    International Nuclear Information System (INIS)

    Sugimoto, Yasunobu; Takezawa, Yasunori; Matsuo, Tatsuhito; Ueno, Yutaka; Minakata, Shiho; Tanaka, Hidehiro; Wakabayashi, Katsuzo

    2008-01-01

    In order to clarify the structural changes related to the regulation mechanism in skeletal muscle contraction, the intensity changes of thin filament-based reflections were investigated by X-ray fiber diffraction. The time course and extent of intensity changes of the first to third order troponin (TN)-associated meridional reflections with a basic repeat of 38.4 nm were different for each of these reflections. The intensity of the first and second thin filament layer lines changed in a reciprocal manner both during initial activation and during the force generation process. The axial spacings of the TN-meridional reflections decreased by ∼0.1% upon activation relative to the relaxing state and increased by ∼0.24% in the force generation state, in line with that of the 2.7-nm reflection. Ca 2+ -binding to TN triggered the shortening and a change in the helical symmetry of the thin filaments. Modeling of the structural changes using the intensities of the thin filament-based reflections suggested that the conformation of the globular core domain of TN altered upon activation, undergoing additional conformational changes at the tension plateau. The tail domain of TN moved together with tropomyosin during contraction. The results indicate that the structural changes of regulatory proteins bound to the actin filaments occur in two steps, the first in response to the Ca 2+ -binding and the second induced by actomyosin interaction

  15. Alcohol impairs skeletal muscle protein synthesis and mTOR signaling in a time-dependent manner following electrically stimulated muscle contraction.

    Science.gov (United States)

    Steiner, Jennifer L; Lang, Charles H

    2014-11-15

    Alcohol (EtOH) decreases protein synthesis and mammalian target of rapamycin (mTOR)-mediated signaling and blunts the anabolic response to growth factors in skeletal muscle. The purpose of the current investigation was to determine whether acute EtOH intoxication antagonizes the contraction-induced increase in protein synthesis and mTOR signaling in skeletal muscle. Fasted male mice were injected intraperitoneally with 3 g/kg EtOH or saline (control), and the right hindlimb was electrically stimulated (10 sets of 6 contractions). The gastrocnemius muscle complex was collected 30 min, 4 h, or 12 h after stimulation. EtOH decreased in vivo basal protein synthesis (PS) in the nonstimulated muscle compared with time-matched Controls at 30 min, 4 h, and 12 h. In Control, but not EtOH, PS was decreased 15% after 30 min. In contrast, PS was increased in Control 4 h poststimulation but remained unchanged in EtOH. Last, stimulation increased PS 10% in Control and EtOH at 12 h, even though the absolute rate remained reduced by EtOH. The stimulation-induced increase in the phosphorylation of S6K1 Thr(421)/Ser(424) (20-52%), S6K1 Thr(389) (45-57%), and its substrate rpS6 Ser(240/244) (37-72%) was blunted by EtOH at 30 min, 4 h, and 12 h. Phosphorylation of 4E-BP1 Ser(65) was also attenuated by EtOH (61%) at 4 h. Conversely, phosphorylation of extracellular signal-regulated kinase Thr(202)/Tyr(204) was increased by stimulation in Control and EtOH mice at 30 min but only in Control at 4 h. Our data indicate that acute EtOH intoxication suppresses muscle protein synthesis for at least 12 h and greatly impairs contraction-induced changes in synthesis and mTOR signaling. Copyright © 2014 the American Physiological Society.

  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. 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...

  18. Alpha adrenergic receptor blockade increases capillarisation and fractional O2 extraction and lowers blood flow in contracting human skeletal muscle

    DEFF Research Database (Denmark)

    Mortensen, Stefan P; Egginton, Stuart; Madsen, Mads

    2017-01-01

    AIM: To investigate the effect of elevated basal shear stress on angiogenesis in humans, and the role of enhanced skeletal muscle capillarisation on blood flow and O2 extraction. METHODS: Limb haemodynamics and O2 extraction was measured at rest and during one-leg knee-extensor exercise (12 and 24W......) in 10 healthy untrained young men before and after 4 weeks treatment with an α1 receptor-antagonist (Terazosin, 1-2 mg day(-1) ). Corresponding biopsies were taken from the m. vastus lateralis. RESULTS: Resting leg blood flow was increased by 57% 6 hours following Terazosin treatment (P... basal capillary-to-fibre ratio was 1.69±0.08 and increased to 1.90±0.08 after treatment (Pblood flow and venous lactate levels lower (6-7%; P

  19. New insights into structure-function relationship of the DHPR beta1a subunit in skeletal muscle excitation-contraction coupling using zebrafish 'relaxed' as an expression system

    International Nuclear Information System (INIS)

    Dayal, A.

    2010-01-01

    The paralyzed zebrafish strain relaxed carries a null mutation for the skeletal muscle dihydropyridine receptor (DHPR) [beta]1a subunit. The lack of [beta]1a not only impedes functional [alpha]1S membrane expression but also precludes the skeletal muscle-specific ultrastructural arrangement of DHPRs into tetrads opposite ryanodine receptor (RyR1), coherent with the absence of skeletal muscle excitation-contraction (EC) coupling. With the plethora of experimental approaches feasible with zebrafish model organism and importantly with the [beta]1-null mutation having a monogenetic inheritance and because of the survival of the relaxed larvae for some days, we were able to establish the zebrafish relaxed as an expression system. Linking in vitro to in vivo observations, a clear differentiation between the major functional roles of [beta] subunits in EC coupling was feasible. The skeletal muscle [beta]1a subunit was able to restore all parameters of EC coupling upon expression in relaxed myotubes and larvae. Expression of the phylogenetically closest isoform to [beta]1a, the cardiac/neuronal [beta]2a subunit or the most distant neuronal [beta]M from the housefly in relaxed myotubes and larvae was likewise able to fully restore [alpha]1S triad targeting and facilitate charge movement. However, efficient tetrad formation and thus intact DHPR-RyR1 coupling was exclusively promoted by the [beta]1a isoform. Consequently, we postulated a model according to which [beta]1a acts as a unique allosteric modifier of [alpha]1S conformation crucial for skeletal muscle EC coupling. Therefore, unique structural elements in [beta]1a must be present which endow it with this exclusive property. Earlier, a unique hydrophobic heptad repeat motif (LVV) in the [beta]1a C-terminus was postulated by others to be essential for skeletal muscle EC coupling. We wanted to address the question if the proposed [beta]1a heptad repeat motif could be an active element of the DHPR-RyR1 signal transduction

  20. 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.

  1. The Effect of Exercise on the Skeletal Muscle Phospholipidome of Rats Fed a High-Fat Diet

    Directory of Open Access Journals (Sweden)

    Jong Sam Lee

    2010-10-01

    Full Text Available The aim of this study was to examine the effect of endurance training on skeletal muscle phospholipid molecular species from high-fat fed rats. Twelve female Sprague-Dawley rats were fed a high-fat diet (78.1% energy. The rats were randomly divided into two groups, a sedentary control group and a trained group (125 min of treadmill running at 8 m/min, 4 days/wk for 4 weeks. Forty-eight hours after their last training bout phospholipids were extracted from the red and white vastus lateralis and analyzed by electrospray-ionization mass spectrometry. Exercise training was associated with significant alterations in the relative abundance of a number of phospholipid molecular species. These changes were more prominent in red vastus lateralis than white vastus lateralis. The largest observed change was an increase of ~30% in the abundance of 1-palmitoyl-2-linoleoyl phosphatidylcholine ions in oxidative fibers. Reductions in the relative abundance of a number of phospholipids containing long-chain n-3 polyunsaturated fatty acids were also observed. These data suggest a possible reduction in phospholipid remodeling in the trained animals. This results in a decrease in the phospholipid n-3 to n-6 ratio that may in turn influence endurance capacity.

  2. In utero glucocorticoid (GLC) exposure reduces fetal skeletal muscle growth in rats

    Science.gov (United States)

    Maternal undernutrition and stress expose the fetus to above normal levels of GLC and predispose to intrauterine growth restriction. The aim of this study was to determine if fetal GLC exposure impairs skeletal muscle growth independently of maternal undernutrition. Three groups (n=7/group) of timed...

  3. Body, heart, thyroid gland and skeletal muscle weight changes in rats with altered thyroid status

    Czech Academy of Sciences Publication Activity Database

    Soukup, Tomáš; Zachařová, Gisela; Smerdu, V.; Jirmanová, Isa

    2001-01-01

    Roč. 50, č. 6 (2001), s. 619-626 ISSN 0862-8408 R&D Projects: GA ČR GA304/00/1653 Institutional research plan: CEZ:AV0Z5011922 Keywords : thyroid state * skeletal muscles * body and organ weight Subject RIV: FH - Neurology Impact factor: 1.027, year: 2001

  4. 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)

  5. SPASMOLYTIC ACTIVITY OF THE AQUEOUS AND ETHANOL CELERY LEAVES (APIUM GRAVEOLENS L. EXTRACTS ON THE CONTRACTION OF ISOLATED RAT ILEUM

    Directory of Open Access Journals (Sweden)

    Suzana Branković

    2015-06-01

    Full Text Available Celery (Apium graveolens L. is a plant species in the family Apiaceae, which has been used in traditional medicine for the treatment of gastrointestinal diseases. This study investigated the effects of aqueous and ethanol extracts from celery leaves on intestinal contractility. Air-dried and powdered leaves were extracted with distilled water and 96% ethanol, respectively. The activities of the extracts on the smooth muscle contractions were evaluated using isolated rat ileum model. The isolated rat ileum was mounted in a 10ml tissue bath. The results suggest that the cumulative concentrations of the extracts of celery statistically significantly inhibited spontaneous rat ileum contractions (p<0.01. The extracts dose-dependently reduced the contractile effects of acetylcholine on the isolated ileum (p<0.05. Ethanol extract exhibited significantly greater relaxant activity than the aqueous extract (p<0.05. These results suggest that the aqueous and ethanol extracts of celery leaves can produce the inhibition of the spontaneous rat ileum contractions and contractions induced by acetylcholine. These data indicate that celery extracts act as intestinal smooth muscle relaxants, which justifies their use in gastrointestinal disorders.

  6. [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.

  7. Vitamin A Oral Supplementation Induces Oxidative Stress and Suppresses IL-10 and HSP70 in Skeletal Muscle of Trained Rats

    Directory of Open Access Journals (Sweden)

    Lyvia Lintzmaier Petiz

    2017-04-01

    Full Text Available Exercise training intensity is the major variant that influences the relationship between exercise, redox balance, and immune response. Supplement intake is a common practice for oxidative stress prevention; the effects of vitamin A (VA on exercise training are not yet described, even though this molecule exhibits antioxidant properties. We investigated the role of VA supplementation on redox and immune responses of adult Wistar rats subjected to swimming training. Animals were divided into four groups: sedentary, sedentary + VA, exercise training, and exercise training + VA. Over eight weeks, animals were submitted to intense swimming 5 times/week and a VA daily intake of 450 retinol equivalents/day. VA impaired the total serum antioxidant capacity acquired by exercise, with no change in interleukin-1β and tumor necrosis factor-α levels. In skeletal muscle, VA caused lipid peroxidation and protein damage without differences in antioxidant enzyme activities; however, Western blot analysis showed that expression of superoxide dismutase-1 was downregulated, and upregulation of superoxide dismutase-2 induced by exercise was blunted by VA. Furthermore, VA supplementation decreased anti-inflammatory interleukin-10 and heat shock protein 70 expression, important factors for positive exercise adaptations and tissue damage prevention. Our data showed that VA supplementation did not confer any antioxidative and/or protective effects, attenuating exercise-acquired benefits in the skeletal muscle.

  8. 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.

  9. 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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  12. Comparison of T-2 Toxin and HT-2 Toxin Distributed in the Skeletal System with That in Other Tissues of Rats by Acute Toxicity Test.

    Science.gov (United States)

    Yu, Fang Fang; Lin, Xia Lu; Yang, Lei; Liu, Huan; Wang, Xi; Fang, Hua; Lammi, ZMikko J; Guo, Xiong

    2017-11-01

    Twelve healthy rats were divided into the T-2 toxin group receiving gavage of 1 mg/kg T-2 toxin and the control group receiving gavage of normal saline. Total relative concentrations of T-2 toxin and HT-2 toxin in the skeletal system (thighbone, knee joints, and costal cartilage) were significantly higher than those in the heart, liver, and kidneys (P skeletal system (thighbone and costal cartilage) were also significantly higher than those in the heart, liver, and kidneys. The rats administered T-2 toxin showed rapid metabolism compared with that in rats administered HT-2 toxin, and the metabolic conversion rates in the different tissues were 68.20%-90.70%. Copyright © 2017 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

  13. Leucine-Enriched Essential Amino Acids Augment Muscle Glycogen Content in Rats Seven Days after Eccentric Contraction

    Directory of Open Access Journals (Sweden)

    Hiroyuki Kato

    2017-10-01

    Full Text Available Eccentric contractions induce muscle damage, which impairs recovery of glycogen and adenosine tri-phosphate (ATP content over several days. Leucine-enriched essential amino acids (LEAAs enhance the recovery in muscles that are damaged after eccentric contractions. However, the role of LEAAs in this process remains unclear. We evaluated the content in glycogen and high energy phosphates molecules (phosphocreatine (PCr, adenosine di-phosphate (ADP and ATP in rats that were following electrically stimulated eccentric contractions. Muscle glycogen content decreased immediately after the contraction and remained low for the first three days after the stimulation, but increased seven days after the eccentric contraction. LEAAs administration did not change muscle glycogen content during the first three days after the contraction. Interestingly, however, it induced a further increase in muscle glycogen seven days after the stimulation. Contrarily, ATP content decreased immediately after the eccentric contraction, and remained lower for up to seven days after. Additionally, LEAAs administration did not affect the ATP content over the experimental period. Finally, ADP and PCr levels did not significantly change after the contractions or LEAA administration. LEAAs modulate the recovery of glycogen content in muscle after damage-inducing exercise.

  14. 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

  15. 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.

  16. 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

  17. 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.

  18. Gestational Protein Restriction in Wistar Rats; Effect of Taurine Supplementation on Properties of Newborn Skeletal Muscle

    DEFF Research Database (Denmark)

    Larsen, Lea Hüche; Sandø-Pedersen, Sofie; Ørstrup, Laura Kofoed Hvidsten

    2017-01-01

    Taurine ameliorates changes occurring in newborn skeletal muscle as a result of gestational protein restriction in C57BL/6 mice, but taurine supplementation effects may be exaggerated in C57BL/6 mice due to their inherent excessive taurinuria.We examined if maternal taurine supplementation could...... by taurine supplementation (LP-Tau). LP-Tau offspring had significantly lower birth weight compared to controls. Gene expression profiling revealed 895 significantly changed genes, mainly an LP-induced down-regulation of genes involved in protein translation. Taurine fully or partially rescued 32......% of these changes, but with no distinct pattern as to which genes were rescued.Skeletal muscle taurine content in LP-Tau offspring was increased, but no changes in mRNA levels of the taurine synthesis pathway were observed. Taurine transporter mRNA levels, but not protein levels, were increased by LP diet...

  19. 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

  20. ESTRADIOL IN FEMALES MAY NEGATE SKELETAL MUSCLE MYOSTATIN MRNA EXPRESSION AND SERUM MYOSTATIN PROPEPTIDE LEVELS AFTER ECCENTRIC MUSCLE CONTRACTIONS

    Directory of Open Access Journals (Sweden)

    Darryn S. Willoughby

    2006-12-01

    Full Text Available Eccentric contractions produce a significant degree of inflammation and muscle injury that may increase the expression of myostatin. Due to its anti- oxidant and anti-flammatory effects, circulating 17-β estradiol (E2 may attenuate myostatin expression. Eight males and eight females performed 7 sets of 10 reps of eccentric contractions of the knee extensors at 150% 1-RM. Each female performed the eccentric exercise bout on a day that fell within her mid-luteal phase (d 21-23 of her 28-d cycle. Blood and muscle samples were obtained before and 6 and 24 h after exercise, while additional blood samples were obtained at 48 and 72 h after exercise. Serum E2 and myostatin LAP/propeptide (LAP/pro levels were determined with ELISA, and myostatin mRNA expression determined using RT-PCR. Data were analyzed with two-way ANOVA and bivariate correlations (p 0.05. Compared to pre-exercise, males had significant increases (p < 0.05 in LAP/propetide and mRNA of 78% and 28%, respectively, at 24 h post-exercise, whereas females underwent respective decreases of 10% and 21%. E2 and LAP/propeptide were correlated at 6 h (r = -0.804, p = 0.016 and 24 h post- exercise (r = -0.841, p = 0.009 in males, whereas in females E2 levels were correlated to myostatin mRNA at 6 h (r =0.739, p = 0.036 and 24 h (r = 0.813, p = 0.014 post-exercise and LAP/propeptide at 6 h (r = 0.713, p = 0.047 and 24 h (r = 0.735, p = 0.038. In females, myostatin mRNA expression and serum LAP/propeptide levels do not appear to be significantly up-regulated following eccentric exercise, and may be due to higher levels of circulating E2

  1. Regulation and role of hormone-sensitive lipase in rat skeletal muscle

    DEFF Research Database (Denmark)

    Donsmark, Morten; Langfort, Jozef; Holm, Cecilia

    2004-01-01

    the effects of contractions and adrenaline on HSL activity are partially additive. In line with the view that the two stimuli act by different mechanisms, training increases contraction-mediated HSL activation but diminishes adrenaline-mediated HSL activation in muscle. In conclusion, HSL is present...... fibre types, being higher in oxidative fibres than in glycolytic fibres. When analysed under conditions optimal for HSL, neutral lipase activity in muscle can be stimulated by adrenaline as well as by contractions. These increases are abolished by the presence of anti-HSL antibody during analysis....... Moreover, immunoprecipitation with affinity-purified anti-HSL antibody causes similar reductions in muscle HSL protein concentration and in measured neutral lipase responses to contractions. The immunoreactive HSL in muscle is stimulated by adrenaline via beta-adrenergic activation of c...

  2. Membrane depolarization increases ryanodine sensitivity to Ca2+ release to the cytosol in L6 skeletal muscle cells: Implications for excitation-contraction coupling.

    Science.gov (United States)

    Pitake, Saumitra; Ochs, Raymond S

    2016-04-01

    The dihydropyridine receptor in the plasma membrane and the ryanodine receptor in the sarcoplasmic reticulum are known to physically interact in the process of excitation-contraction coupling. However, the mechanism for subsequent Ca(2+) release through the ryanodine receptor is unknown. Our lab has previously presented evidence that the dihydropyridine receptor and ryanodine receptor combine as a channel for the entry of Ca(2+) under resting conditions, known as store operated calcium entry. Here, we provide evidence that depolarization during excitation-contraction coupling causes the dihydropyridine receptor to disengage from the ryanodine receptor. The newly freed ryanodine receptor can then transport Ca(2+) from the sarcoplasmic reticulum to the cytosol. Experimentally, this should more greatly expose the ryanodine receptor to exogenous ryanodine. To examine this hypothesis, we titrated L6 skeletal muscle cells with ryanodine in resting and excited (depolarized) states. When L6 muscle cells were depolarized with high potassium or exposed to the dihydropyridine receptor agonist BAYK-8644, known to induce dihydropyridine receptor movement within the membrane, ryanodine sensitivity was enhanced. However, ryanodine sensitivity was unaffected when Ca(2+) was elevated without depolarization by the ryanodine receptor agonist chloromethylcresol, or by increasing Ca(2+) concentration in the media. Ca(2+) entry currents (from the extracellular space) during excitation were strongly inhibited by ryanodine, but Ca(2+) entry currents in the resting state were not. We conclude that excitation releases the ryanodine receptor from occlusion by the dihydropyridine receptor, enabling Ca(2+) release from the ryanodine receptor to the cytosol. © 2015 by the Society for Experimental Biology and Medicine.

  3. Contractions activate hormone-sensitive lipase in rat muscle by protein kinase C and mitogen-activated protein kinase

    DEFF Research Database (Denmark)

    Donsmark, Morten; Langfort, Jozef; Holm, Cecilia

    2003-01-01

    and contractions. Adrenaline acts via cAMP-dependent protein kinase (PKA). The signalling mediating the effect of contractions is unknown and was explored in this study. Incubated soleus muscles from 70 g male rats were electrically stimulated to perform repeated tetanic contractions for 5 min. The contraction......Intramuscular triacylglycerol is an important energy store and is also related to insulin resistance. The mobilization of fatty acids from this pool is probably regulated by hormone-sensitive lipase (HSL), which has recently been shown to exist in muscle and to be activated by both adrenaline......-induced activation of HSL was abolished by the protein kinase C (PKC) inhibitors bisindolylmaleimide I and calphostin C and reduced 50% by the mitogen-activated protein kinase kinase (MEK) inhibitor U0126, which also completely blocked extracellular signal-regulated kinase (ERK) 1 and 2 phosphorylation. None...

  4. Positron emission tomography detects greater blood flow and less blood flow heterogeneity in the exercising skeletal muscles of old compared with young men during fatiguing contractions

    Science.gov (United States)

    Rudroff, Thorsten; Weissman, Jessica A; Bucci, Marco; Seppänen, Marko; Kaskinoro, Kimmo; Heinonen, Ilkka; Kalliokoski, Kari K

    2014-01-01

    The purpose of this study was to investigate blood flow and its heterogeneity within and among the knee muscles in five young (26 ± 6 years) and five old (77 ± 6 years) healthy men with similar levels of physical activity while they performed two types of submaximal fatiguing isometric contraction that required either force or position control. Positron emission tomography (PET) and [15O]-H2O were used to determine blood flow at 2 min (beginning) and 12 min (end) after the start of the tasks. Young and old men had similar maximal forces and endurance times for the fatiguing tasks. Although muscle volumes were lower in the older subjects, total muscle blood flow was similar in both groups (young men: 25.8 ± 12.6 ml min−1; old men: 25.1 ± 15.4 ml min−1; age main effect, P = 0.77) as blood flow per unit mass of muscle in the exercising knee extensors was greater in the older (12.5 ± 6.2 ml min−1 (100 g)−1) than the younger (8.6 ± 3.6 ml min−1 (100 g)−1) men (age main effect, P = 0.001). Further, blood flow heterogeneity in the exercising knee extensors was significantly lower in the older (56 ± 27%) than the younger (67 ± 34%) men. Together, these data show that although skeletal muscles are smaller in older subjects, based on the intact neural drive to the muscle and the greater, less heterogeneous blood flow per gram of muscle, old fit muscle achieves adequate exercise hyperaemia. Key points The results of previous studies that attempted to demonstrate the effects of ageing on skeletal muscle blood flow are controversial because these studies used indirect assessments of skeletal muscle blood flow obtained via whole limb blood flow measurements that provide no information on the distribution of blood flow within particular muscles. We used positron emission tomography to measure blood flow per gram of muscle in old and young men with similar levels of physical activity

  5. Skeletal muscle cell contraction reduces a novel myokine, chemokine (C-X-C motif) ligand 10 (CXCL10): potential roles in exercise-regulated angiogenesis.

    Science.gov (United States)

    Ishiuchi, Yuri; Sato, Hitoshi; Tsujimura, Kazuki; Kawaguchi, Hideo; Matsuwaki, Takashi; Yamanouchi, Keitaro; Nishihara, Masugi; Nedachi, Taku

    2018-01-01

    Accumulating evidence indicates that skeletal muscle secrets proteins referred to as myokines and that exercise contributes to their regulation. In this study, we propose that chemokine (C-X-C motif) ligand 10 (CXCL10) functions as a novel myokine. Initially, we stimulated differentiated C2C12 myotubes with or without electrical pulse stimulation (EPS) to identify novel myokines. Cytokine array analysis revealed that CXCL10 secretion was significantly reduced by EPS, which was further confirmed by enzyme-linked immunosorbent assay and quantitative polymerase chain reaction analysis. Treadmill experiments in mice identified significant reduction of Cxcl10 gene expression in the soleus muscle. Additionally, contraction-dependent p38 MAPK activation appeared to be involved in this reduction. Furthermore, C2C12 conditioned medium obtained after applying EPS could induce survival of MSS31, a vascular endothelial cell model, which was partially attenuated by the addition of recombinant CXCL10. Overall, our findings suggest CXCL10 as a novel exercise-reducible myokine, to control endothelial cell viability.

  6. Contraction-induced increases in Na+-K+-ATPase mRNA levels in human skeletal muscle are not amplified by activation of additional muscle mass

    DEFF Research Database (Denmark)

    Nordsborg, Nikolai; Thomassen, Martin; Lundby, Carsten

    2005-01-01

    The present study tested the hypothesis that exercise with a large compared with a small active muscle mass results in a higher contraction-induced increase in Na+-K+-ATPase mRNA expression due to greater hormonal responses. Furthermore, the relative abundance of Na+-K+-ATPase subunit a1, a2, a3, a......% of the a2 expression, and no reliable detection of a3 and a4 was possible. In conclusion, activation of additional muscle mass does not result in a higher exercise-induced increase in Na+-K+-ATPase subunit-specific mRNA.......4, ß1, ß2, and ß3 mRNA in human skeletal muscle was investigated. On two occasions, eight subjects performed one-legged knee extension exercise (L) or combined one-legged knee extension and bilateral arm cranking (AL) for 5.00, 4.25, 3.50, 2.75, and 2.00 min separated by 3 min of rest. Leg exercise...

  7. Whey protein hydrolysate enhances HSP90 but does not alter HSP60 and HSP25 in skeletal muscle of rats.

    Directory of Open Access Journals (Sweden)

    Carolina Soares Moura

    Full Text Available Whey protein hydrolysate (WPH intake has shown to increase HSP70 expression. The aim of the present study was to investigate whether WPH intake would also influences HSP90, HSP60 and HSP25 expression, as well as associated parameters. Forty-eight male Wistar rats were divided into sedentary (unstressed and exercised (stressed groups, and were fed with three different sources of protein: whey protein (WP, whey protein hydrolysate (WPH and casein (CAS as a control, based on the AIN93G diet for 3 weeks. WPH intake increased HSP90 expression in both sedentary and exercised animals compared to WP or CAS, however no alteration was found from exercise or diet to HSP60 or HSP25. Co-chaperone Aha1 and p-HSF1 were also increased in the exercised animals fed with WPH in comparison with WP or CAS, consistent with enhanced HSP90 expression. VEGF and p-AKT were increased in the WPH exercised group. No alteration was found in BCKDH, PI3-Kinase (p85, GFAT, OGT or PGC for diet or exercise. The antioxidant system GPx, catalase and SOD showed different responses to diet and exercise. The data indicate that WPH intake enhanced factors related to cell survival, such as HSP90 and VEGF, but does not alter HSP60 or HSP25 in rat skeletal muscle.

  8. 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

  9. Muscle Contraction.

    Science.gov (United States)

    Sweeney, H Lee; Hammers, David W

    2018-02-01

    SUMMARYMuscle cells are designed to generate force and movement. There are three types of mammalian muscles-skeletal, cardiac, and smooth. Skeletal muscles are attached to bones and move them relative to each other. Cardiac muscle comprises the heart, which pumps blood through the vasculature. Skeletal and cardiac muscles are known as striated muscles, because the filaments of actin and myosin that power their contraction are organized into repeating arrays, called sarcomeres, that have a striated microscopic appearance. Smooth muscle does not contain sarcomeres but uses the contraction of filaments of actin and myosin to constrict blood vessels and move the contents of hollow organs in the body. Here, we review the principal molecular organization of the three types of muscle and their contractile regulation through signaling mechanisms and discuss their major structural and functional similarities that hint at the possible evolutionary relationships between the cell types. Copyright © 2018 Cold Spring Harbor Laboratory Press; all rights reserved.

  10. Genomic expression analysis of rat chromosome 4 for skeletal traits at femoral neck

    OpenAIRE

    Alam, Imranul; Sun, Qiwei; Liu, Lixiang; Koller, Daniel L.; Liu, Yunlong; Edenberg, Howard J.; Econs, Michael J.; Foroud, Tatiana; Turner, Charles H.

    2008-01-01

    Hip fracture is the most devastating osteoporotic fracture type with significant morbidity and mortality. Several studies in humans and animal models identified chromosomal regions linked to hip size and bone mass. Previously, we identified that the region of 4q21-q41 on rat chromosome (Chr) 4 harbors multiple femoral neck quantitative trait loci (QTLs) in inbred Fischer 344 (F344) and Lewis (LEW) rats. The purpose of this study is to identify the candidate genes for femoral neck structure an...

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

    Science.gov (United States)

    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.

  12. Vagally mediated effects of brain stem dopamine on gastric tone and phasic contractions of the rat.

    Science.gov (United States)

    Anselmi, L; Toti, L; Bove, C; Travagli, R A

    2017-11-01

    Dopamine (DA)-containing fibers and neurons are embedded within the brain stem dorsal vagal complex (DVC); we have shown previously that DA modulates the membrane properties of neurons of the dorsal motor nucleus of the vagus (DMV) via DA1 and DA2 receptors. The vagally dependent modulation of gastric tone and phasic contractions, i.e., motility, by DA, however, has not been characterized. With the use of microinjections of DA in the DVC while recording gastric tone and motility, the aims of the present study were 1 ) assess the gastric effects of brain stem DA application, 2 ) identify the DA receptor subtype, and, 3 ) identify the postganglionic pathway(s) activated. Dopamine microinjection in the DVC decreased gastric tone and motility in both corpus and antrum in 29 of 34 rats, and the effects were abolished by ipsilateral vagotomy and fourth ventricular treatment with the selective DA2 receptor antagonist L741,626 but not by application of the selective DA1 receptor antagonist SCH 23390. Systemic administration of the cholinergic antagonist atropine attenuated the inhibition of corpus and antrum tone in response to DA microinjection in the DVC. Conversely, systemic administration of the nitric oxide synthase inhibitor nitro-l-arginine methyl ester did not alter the DA-induced decrease in gastric tone and motility. Our data provide evidence of a dopaminergic modulation of a brain stem vagal neurocircuit that controls gastric tone and motility. NEW & NOTEWORTHY Dopamine administration in the brain stem decreases gastric tone and phasic contractions. The gastric effects of dopamine are mediated via dopamine 2 receptors on neurons of the dorsal motor nucleus of the vagus. The inhibitory effects of dopamine are mediated via inhibition of the postganglionic cholinergic pathway. Copyright © 2017 the American Physiological Society.

  13. Histomorphometric analysis of the response of rat skeletal muscle to swimming, immobilization and rehabilitation

    Directory of Open Access Journals (Sweden)

    C.C.F. Nascimento

    2008-09-01

    Full Text Available The objective of the present study was to determine to what extent, if any, swimming training applied before immobilization in a cast interferes with the rehabilitation process in rat muscles. Female Wistar rats, mean weight 260.52 ± 16.26 g, were divided into 4 groups of 6 rats each: control, 6 weeks under baseline conditions; trained, swimming training for 6 weeks; trained-immobilized, swimming training for 6 weeks and then immobilized for 1 week; trained-immobilized-rehabilitated, swimming training for 6 weeks, immobilized for 1 week and then remobilized with swimming for 2 weeks. The animals were then sacrificed and the soleus and tibialis anterior muscles were dissected, frozen in liquid nitrogen and processed histochemically (H&E and mATPase. Data were analyzed statistically by the mixed effects linear model (P < 0.05. Cytoarchitectural changes such as degenerative characteristics in the immobilized group and regenerative characteristics such as centralized nucleus, fiber size variation and cell fragmentation in the groups submitted to swimming were more significant in the soleus muscle. The diameters of the lesser soleus type 1 and type 2A fibers were significantly reduced in the trained-immobilized group compared to the trained group (P < 0.001. In the tibialis anterior, there was an increase in the number of type 2B fibers and a reduction in type 2A fibers when trained-immobilized rats were compared to trained rats (P < 0.001. In trained-immobilized-rehabilitated rats, there was a reduction in type 2B fibers and an increase in type 2A fibers compared to trained-immobilized rats (P < 0.009. We concluded that swimming training did not minimize the deleterious effects of immobilization on the muscles studied and that remobilization did not favor tissue re-adaptation.

  14. Methanol fractionations of Catha edulis Frosk (Celastraceae) contracted Lewis rat aorta in vitro: a comparison between crimson and green leaves.

    Science.gov (United States)

    Mahmood, Samira Abdulla; Pavlovic, Dragan; Hoffmann, Ulrich

    2009-05-07

    The study investigated the effect of methanol extract and its fractionations obtained from Yemeni khat on the smooth muscle isometric tension in Lewis rat aortal ring preparations and compared the effects of the crimson and green leaves. Khat leaves were sorted into green (khat Light; KL) and crimson (khat Dark; KD) leaves, extracted with methanol, followed with solvent-solvent extraction (benzene, chloroform and ethylacetate). The contractile activity of the fractions was tested using aortal ring preparations. The control (phenylepherine contraction) methanol extracts contracted aortas at concentrations 250, 125 and 67.5 microg/ml buffer by 80.2%, 57.3%, 26.4% and 81.5%, 65.6%, 24.6% for KL and KD, respectively. Fractions of benzene (BF) and ethylacetate (EaF) contracted the aorta with 2 microgm, whereas, chloroform (ChF) with 1 microgm/1 ml buffer was less potent. The shape of contraction curve produced by EaF differed from that of ChF and BF of both (KL and KD). The EaF induced-contraction peaked after 3.3 +/- 0.94 mins, whereas those of BF and CHF peaked after 18.0 +/- 2.2, 19.7 +/- 0.94 mins, respectively. Pre-incubation with nifedipine (10(-6) M) insignificantly reduced the contraction induced by all fractionations, but prazosin (10(-6) M) reduced the contraction by 81.9%, 63.1%, 71.8% with p = 0.23, 0.09, 0.15 for BF, ChF and EaF of KL, respectively. It significantly reduced contraction of ChF, 64.1%; p = 0.02, and of EaF, 73.5%; p = 0.04 of KD, while the reduction in contraction of BF was 63.1%; p = 0.06. In conclusion, fractions of green and crimson Yemeni khat leaves contracted aortas of Lewis rats. Both leaves behave almost similarly. Contraction induced by chloroform fraction produced alpha-sympathetic activity.

  15. L-arginine and Arginase Products Potentiate Dexmedetomidine-induced Contractions in the Rat Aorta.

    Science.gov (United States)

    Wong, Emily S W; Man, Ricky Y K; Ng, Kwok F J; Leung, Susan W S; Vanhoutte, Paul M

    2018-03-01

    The α2-adrenergic sedative/anesthetic agent dexmedetomidine exerts biphasic effects on isolated arteries, causing endothelium-dependent relaxations at concentrations at or below 30 nM, followed by contractions at higher concentrations. L-arginine is a common substrate of endothelial nitric oxide synthase and arginases. This study was designed to investigate the role of L-arginine in modulating the overall vascular response to dexmedetomidine. Isometric tension was measured in isolated aortic rings of Sprague Dawley rats. Cumulative concentrations of dexmedetomidine (10 nM to 10 μM) were added to quiescent rings (with and without endothelium) after previous incubation with vehicle, N-nitro-L-arginine methyl ester hydrochloride (L-NAME; nitric oxide synthase inhibitor), prazosin (α1-adrenergic antagonist), rauwolscine (α2-adrenergic antagonist), L-arginine, (S)-(2-boronethyl)-L-cysteine hydrochloride (arginase inhibitor), N-hydroxy-L-arginine (arginase inhibitor), urea and/or ornithine. In some preparations, immunofluorescent staining, immunoblotting, or measurement of urea content were performed. Dexmedetomidine did not contract control rings with endothelium but evoked concentration-dependent increases in tension in such rings treated with L-NAME (Emax 50 ± 4%) or after endothelium-removal (Emax 74 ± 5%; N = 7 to 12). Exogenous L-arginine augmented the dexmedetomidine-induced contractions in the presence of L-NAME (Emax 75 ± 3%). This potentiation was abolished by (S)-(2-boronethyl)-L-cysteine hydrochloride (Emax 16 ± 4%) and N-hydroxy-L-arginine (Emax 18 ± 4%). Either urea or ornithine, the downstream arginase products, had a similar potentiating effect as L-arginine. Immunoassay measurements demonstrated an upregulation of arginase I by L-arginine treatment in the presence of L-NAME (N = 4). These results suggest that when vascular nitric oxide homeostasis is impaired, the potentiation of the vasoconstrictor effect of

  16. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  18. Fiber specific changes in sphingolipid metabolism in skeletal muscles of hyperthyroid rats.

    Science.gov (United States)

    Chabowski, A; Zendzian-Piotrowska, M; Mikłosz, A; Łukaszuk, B; Kurek, K; Górski, J

    2013-07-01

    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, with diverse fiber compositions: soleus (slow-twitch oxidative), red (fast-twitch oxidative-glycolytic) and white (fast-twitch glycolytic) section of gastrocnemius. We demonstrated that T3 induced accumulation of sphinganine, ceramide, sphingosine, as well as sphingomyelin, mostly in soleus and in red, but not white section of gastrocnemius. Concomitantly, the activity of serine palmitoyltransferase and acid/neutral ceramidase was increased in more oxidative muscles. In conclusion, hyperthyroidism induced fiber specific changes in the content of sphingolipids that were relatively more related to de novo synthesis of ceramide rather than to its generation via hydrolysis of sphingomyelin.

  19. 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.

  20. 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

  1. Antispasmodic effects of Pycnocycla spinosa seed and aerial part extracts on rat ileum and uterus smooth muscle contractions

    Directory of Open Access Journals (Sweden)

    2008-08-01

    Full Text Available Background and the purpose of study: Hydroalcoholic extract of Pycnocycla spinosa has a relaxant effect on ileum and inhibits castor oil induced diarrhoea in mice. However, effects of P. spinosa seed extracts on ileum and uterus hasn't been investigated.  The aim of this study was to investigate effect of P. spinosa seed and extracts of the aerial part on rat ileum and uterus smooth muscle contraction. Methods: A 70% ethanol extract of seed and aerial parts of P. spinosa was prepared by a percolation method. Uterine horns or ileum were dissected from non-pregnant female Wistar rats (200-230g and cut into longitudinal strips and mounted for isotonic recording under 1g tension in Tyrode's solution. Effects of the extracts were examined on tonic contractions induced by KCl (80mM on both tissues and on phasic spasm induced by oxytocin (0.002iu/ml on the uterus. Results: The aerial part extract inhibited rat ileum contractions induced by 80mM KCl (IC50=42±3.4mg/ml in a concentration dependent manner and it also inhibited rat uterus contraction induced by 80 mM KCl. However, its inhibitory effects were observed with higher concentration of the extract (IC50=420±90mg/ml and at concentration of 1.28mg/ml of the extract in the bath the response was 19±7%.  The aerial part extract (40-640mg/ml also reduced the evoked phasic response of uterus by oxytocin (IC50=71±17.3mg/ml. The seed extract reduced the uterus response to oxytocin in a concentration-dependent manner, and inhibited tissue response completely at 160mg/ml (IC50=27±4mg/ml.  Major conclusion: From this study it was concluded that the seed extract of P. spinosa have similar inhibitory properties on rat isolated uterus and ileum contractions, while the extract of the aerial part of P. spinosa is more selective inhibitor of ileum contraction, and at higher concentrations it also inhibits uterus spasm.

  2. Reduced sarcoplasmic reticulum content of releasable Ca2+ in rat soleus muscle fibres after eccentric contractions

    DEFF Research Database (Denmark)

    Nielsen, J S; Sahlin, K; Ørtenblad, N

    2007-01-01

    AIM: The purpose was to evaluate the effects of fatiguing eccentric contractions (EC) on calcium (Ca2+) handling properties in mammalian type I muscles. We hypothesized that EC reduces both endogenous sarcoplasmic reticulum (SR) content of releasable Ca2+ (eSRCa2+) and myofibrillar Ca2+ sensitivity....... METHODS: Isolated rat soleus muscles performed 30 EC bouts. Single fibres were isolated from the muscle and after mechanical removal of sarcolemma used to measure eSRCa2+, rate of SR Ca2+ loading and myofibrillar Ca2+ sensitivity. RESULTS: Following EC maximal force in whole muscle was reduced by 30......% and 16/100 Hz force ratio by 33%. The eSRCa2+ in fibres from non-stimulated muscles was 45 +/- 5% of the maximal loading capacity. After EC, eSRCa2+ per fibre CSA decreased by 38% (P = 0.05), and the maximal capacity of SR Ca2+ loading was depressed by 32%. There were no effects of EC on either...

  3. Effects of cannabidiol on contractions and calcium signaling in rat ventricular myocytes.

    Science.gov (United States)

    Ali, Ramez M; Al Kury, Lina T; Yang, Keun-Hang Susan; Qureshi, Anwar; Rajesh, Mohanraj; Galadari, Sehamuddin; Shuba, Yaroslav M; Howarth, Frank Christopher; Oz, Murat

    2015-04-01

    Cannabidiol (CBD), a major nonpsychotropic cannabinoid found in Cannabis plant, has been shown to influence cardiovascular functions under various physiological and pathological conditions. In the present study, the effects of CBD on contractility and electrophysiological properties of rat ventricular myocytes were investigated. Video edge detection was used to measure myocyte shortening. Intracellular Ca(2+) was measured in cells loaded with the Ca(2+) sensitive fluorescent indicator fura-2 AM. Whole-cell patch clamp was used to measure action potential and Ca(2+) currents. Radioligand binding was employed to study pharmacological characteristics of CBD binding. CBD (1μM) caused a significant decrease in the amplitudes of electrically evoked myocyte shortening and Ca(2+) transients. However, the amplitudes of caffeine-evoked Ca(2+) transients and the rate of recovery of electrically evoked Ca(2+) transients following caffeine application were not altered. CBD (1μM) significantly decreased the duration of APs. Further studies on L-type Ca(2+) channels indicated that CBD inhibits these channels with IC50 of 0.1μM in a voltage-independent manner. Radioligand studies indicated that the specific binding of [(3)H]Isradipine, was not altered significantly by CBD. The results suggest that CBD depresses myocyte contractility by suppressing L-type Ca(2+) channels at a site different than dihydropyridine binding site and inhibits excitation-contraction coupling in cardiomyocytes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Muscle architecture and fibre characteristics of rat gastrocnemius and semimembranosus muscles during isometric contractions.

    Science.gov (United States)

    Huijing, P A; van Lookeren Campagne, A A; Koper, J F

    1989-01-01

    Rat gastrocnemius medialis (GM) and semimembranosus (SM) muscles have a very different morphology. GM is a very pennate muscle, combining relatively short muscle fibre length with sizable fibre angles and long muscle and aponeurosis lengths. SM is a more parallel-fibred muscle, combining a relatively long fibre length with a small fibre angle and short aponeurosis length. The mechanisms of fibre shortening as well as angle increase are operational in GM as well as SM. However, as a consequence of isometric contraction, changes of fibre length and angle are greater for GM than for SM at any relative muscle length. These differences are particularly notable at short muscle lengths: at 80% of optimum muscle length, fibre length changes of approximately 30% are coupled to fibre angle changes of 15 degrees in GM, while for SM these changes are 4% and 0.6 degrees, respectively. A considerable difference was found for normalized active slack muscle length (GM approximately 80 and SM approximately 45%). This is explained by differences of degree of pennation as well as factors related to differences found for estimated fibre length-force characteristics. Estimated normalized active fibre slack length was considerably smaller for SM than for GM (approximately 40 and 60%, respectively). The most likely explanation of these findings are differences of distribution of optimum fibre lengths, possibly in combination with differences of myofilament lengths and/or fibre length distributions.

  5. NS309 decreases rat detrusor smooth muscle membrane potential and phasic contractions by activating SK3 channels

    Science.gov (United States)

    Parajuli, Shankar P; Hristov, Kiril L; Soder, Rupal P; Kellett, Whitney F; Petkov, Georgi V

    2013-01-01

    Background and Purpose Overactive bladder (OAB) is often associated with abnormally increased detrusor smooth muscle (DSM) contractions. We used NS309, a selective and potent opener of the small or intermediate conductance Ca2+-activated K+ (SK or IK, respectively) channels, to evaluate how SK/IK channel activation modulates DSM function. Experimental Approach We employed single-cell RT-PCR, immunocytochemistry, whole cell patch-clamp in freshly isolated rat DSM cells and isometric tension recordings of isolated DSM strips to explore how the pharmacological activation of SK/IK channels with NS309 modulates DSM function. Key Results We detected SK3 but not SK1, SK2 or IK channels expression at both mRNA and protein levels by RT-PCR and immunocytochemistry in DSM single cells. NS309 (10 μM) significantly increased the whole cell SK currents and hyperpolarized DSM cell resting membrane potential. The NS309 hyperpolarizing effect was blocked by apamin, a selective SK channel inhibitor. NS309 inhibited the spontaneous phasic contraction amplitude, force, frequency, duration and tone of isolated DSM strips in a concentration-dependent manner. The inhibitory effect of NS309 on spontaneous phasic contractions was blocked by apamin but not by TRAM-34, indicating no functional role of the IK channels in rat DSM. NS309 also significantly inhibited the pharmacologically and electrical field stimulation-induced DSM contractions. Conclusions and Implications Our data reveal that SK3 channel is the main SK/IK subtype in rat DSM. Pharmacological activation of SK3 channels with NS309 decreases rat DSM cell excitability and contractility, suggesting that SK3 channels might be potential therapeutic targets to control OAB associated with detrusor overactivity. PMID:23145946

  6. 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

  7. 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.

  8. 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.

  9. Transcriptional profiling of rat skeletal muscle hypertrophy under restriction of blood flow.

    Science.gov (United States)

    Xu, Shouyu; Liu, Xueyun; Chen, Zhenhuang; Li, Gaoquan; Chen, Qin; Zhou, Guoqing; Ma, Ruijie; Yao, Xinmiao; Huang, Xiao

    2016-12-15

    Blood flow restriction (BFR) under low-intensity resistance training (LIRT) can produce similar effects upon muscles to that of high-intensity resistance training (HIRT) while overcoming many of the restrictions to HIRT that occurs in a clinical setting. However, the potential molecular mechanisms of BFR induced muscle hypertrophy remain largely unknown. Here, using a BFR rat model, we aim to better elucidate the mechanisms regulating muscle hypertrophy as induced by BFR and reveal possible clinical therapeutic targets for atrophy cases. We performed genome wide screening with microarray analysis to identify unique differentially expressed genes during rat muscle hypertrophy. We then successfully separated the differentially expressed genes from BRF treated soleus samples by comparing the Affymetrix rat Genome U34 2.0 array with the control. Using qRT-PCR and immunohistochemistry (IHC) we also analyzed other related differentially expressed genes. Results suggested that muscle hypertrophy induced by BFR is essentially regulated by the rate of protein turnover. Specifically, PI3K/AKT and MAPK pathways act as positive regulators in controlling protein synthesis where ubiquitin-proteasome acts as a negative regulator. This represents the first general genome wide level investigation of the gene expression profile in the rat soleus after BFR treatment. This may aid our understanding of the molecular mechanisms regulating and controlling muscle hypertrophy and provide support to the BFR strategies aiming to prevent muscle atrophy in a clinical setting. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Altered expression and insulin-induced trafficking of Na+-K+-ATPase in rat skeletal muscle

    DEFF Research Database (Denmark)

    Galuska, Dana; Kotova, Olga; Barres, Romain

    2009-01-01

    Skeletal muscle Na(+)-K(+)-ATPase plays a central role in the clearance of K(+) from the extracellular fluid, therefore maintaining blood [K(+)]. Na(+)-K(+)-ATPase activity in peripheral tissue is impaired in insulin resistant states. We determined effects of high-fat diet (HFD) and exercise......(+)-K(+)-ATPase activity after 4 wk of HFD. Exercise training restored alpha(1)-, alpha(2)-, and beta(1)-subunit expression and Na(+)-K(+)-ATPase activity to control levels and reduced beta(2)-subunit expression 2.2-fold (P ... phospholemman. Phospholemman mRNA and protein expression were increased after HFD and restored to control levels after ET. Insulin-stimulated translocation of the alpha(2)-subunit to plasma membrane was impaired by HFD, whereas alpha(1)-subunit translocation remained unchanged. Alterations in sodium pump...

  11. Salvia miltiorrhiza Induces Tonic Contraction of the Lower Esophageal Sphincter in Rats via Activation of Extracellular Ca2+ Influx

    Directory of Open Access Journals (Sweden)

    Ching-Chung Tsai

    2015-08-01

    Full Text Available Up to 40% of patients with gastroesophageal reflux disease (GERD suffer from proton pump inhibitor refractory GERD but clinically the medications to strengthen the lower esophageal sphincter (LES to avoid irritating reflux are few in number. This study aimed to examine whether Salvia miltiorrhiza (SM extracts induce tonic contraction of rat LES ex vivo and elucidate the underlying mechanisms. To investigate the mechanism underlying the SM extract-induced contractile effects, rats were pretreated with atropine (a muscarinic receptor antagonist, tetrodotoxin (a sodium channel blocker, nifedipine (a calcium channel blocker, and Ca2+-free Krebs-Henseleit solution with ethylene glycol tetraacetic acid (EGTA, followed by administration of cumulative dosages of SM extracts. SM extracts induced dose-related tonic contraction of the LES, which was unaffected by tetrodotoxin, atropine, or nifedipine. However, the SM extract-induced LES contraction was significantly inhibited by Ca2+-free Krebs-Henseleit solution with EGTA. Next, SM extracts significantly induce extracellular Ca2+ entry into primary LES cells in addition to intracellular Ca2+ release and in a dose-response manner. Confocal fluorescence microscopy showed that the SM extracts consistently induced significant extracellular Ca2+ influx into primary LES cells in a time-dependent manner. In conclusion, SM extracts could induce tonic contraction of LES mainly through the extracellular Ca2+ influx pathway.

  12. Altered Elementary Calcium Release Events and Enhanced Calcium Release by Thymol in Rat Skeletal Muscle

    OpenAIRE

    Szentesi, Péter; Szappanos, Henrietta; Szegedi, Csaba; Gönczi, Monika; Jona, István; Cseri, Julianna; Kovács, László; Csernoch, László

    2004-01-01

    The effects of thymol on steps of excitation-contraction coupling were studied on fast-twitch muscles of rodents. Thymol was found to increase the depolarization-induced release of calcium from the sarcoplasmic reticulum, which could not be attributed to a decreased calcium-dependent inactivation of calcium release channels/ryanodine receptors or altered intramembrane charge movement, but rather to a more efficient coupling of depolarization to channel opening. Thymol increased ryanodine bind...

  13. Development of an Assay Based on the Effects of PGBx on the Isolated Perfused Rat Heart and Rat Skeletal Muscle.

    Science.gov (United States)

    1980-09-01

    had no effect on discphe- nol induced alterations in spontaneous heart rate, but did appear to prevent the increase in coronary flow caused by...Phosphorylase a i -24 activity was also the same in each of the groups examined (Table 2-4). DISCUSSION The ability of PGBx to prevent 2,4-dinitrophenol-induced...euthyroid and hyperthyroid rats. Eur. J. Pharmac. 19, 12-17. Aronson, C. E. and Serlick, E. R. (1977a) Effects of chlorpromazine on the isolated

  14. 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.

  15. Characterization of thyroid hormone effects on Na-K pump and membrane potential of cultured rat skeletal myotubes

    International Nuclear Information System (INIS)

    Brodie, C.; Sampson, S.R.

    1988-01-01

    The purpose of this study was to characterize the effects of thyroid hormone on the Na-K pump and resting membrane potential (EM) of rat skeletal myotubes in culture. Myotubes were obtained from fetal (19-21 day) or neonatal rats (1-2 day) by serial trypsinization and maintained in culture for up to 10 days. Cells were treated with T4 or T3 on day 6 or 7, and measurements were made of EM, [ 3 H]ouabain binding, and ouabain-sensitive 86 Rb uptake at various times thereafter. Hormone treatment increased the values of all three variables within 24 h, plateau levels being attained by 48-72 h. Cycloheximide and actinomycin D totally blocked the effects of thyroid hormone when added together to the cells, thus suggesting that protein synthesis is necessary for the effects of these hormones. Scatchard analysis showed that the new receptors have lower ouabain affinity than those in control. Blockade of spontaneously occurring action potentials with tetrodotoxin, which blocks voltage-dependent Na channels, or Na/H antiporter with amiloride, abolished the hormone effects seen after 24 h and significantly reduced those obtained after 48 h of hormone treatment. The results demonstrate that thyroid hormone-induced increased amount and activity of the electrogenic Na-K pump in cultured myotubes occurs, at least in part, in response to an initial effect to increase Na influx. Moreover, the findings are consistent with the concept that the Na-K pump plays an important role in regulation of EM in this preparation

  16. A leucine-supplemented diet improved protein content of skeletal muscle in young tumor-bearing rats

    Directory of Open Access Journals (Sweden)

    Gomes-Marcondes M.C.C.

    2003-01-01

    Full Text Available Cancer cachexia induces host protein wastage but the mechanisms are poorly understood. Branched-chain amino acids play a regulatory role in the modulation of both protein synthesis and degradation in host tissues. Leucine, an important amino acid in skeletal muscle, is higher oxidized in tumor-bearing animals. A leucine-supplemented diet was used to analyze the effects of Walker 256 tumor growth on body composition in young weanling Wistar rats divided into two main dietary groups: normal diet (N, 18% protein and leucine-rich diet (L, 15% protein plus 3% leucine, which were further subdivided into control (N or L or tumor-bearing (W or LW subgroups. After 12 days, the animals were sacrificed and their carcass analyzed. The tumor-bearing groups showed a decrease in body weight and fat content. Lean carcass mass was lower in the W and LW groups (W = 19.9 ± 0.6, LW = 23.1 ± 1.0 g vs N = 29.4 ± 1.3, L = 28.1 ± 1.9 g, P < 0.05. Tumor weight was similar in both tumor-bearing groups fed either diet. Western blot analysis showed that myosin protein content in gastrocnemius muscle was reduced in tumor-bearing animals (W = 0.234 ± 0.033 vs LW = 0.598 ± 0.036, N = 0.623 ± 0.062, L = 0.697 ± 0.065 arbitrary intensity, P < 0.05. Despite accelerated tumor growth, LW animals exhibited a smaller reduction in lean carcass mass and muscle myosin maintenance, suggesting that excess leucine in the diet could counteract, at least in part, the high host protein wasting in weanling tumor-bearing rats.

  17. Partial Restoration Of Skeletal Strength In Ovariectomized Rats By Treatment With Strontium Salts

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Andersen, Pernille/Høegh; Christgau, Stephan

    AIM Ovariectomy of female rats induces significant bone-loss by depriving endogenous estrogen production. We assessed whether administration of strontium salts had a therapeutic benefit in this animal model of postmenopausal osteoporosis. INTRODUCTION In most women after menopause, the rate of bone...... loss exceeds the rate of bone formation, resulting in a net decrease in bone mass and ultimately in development of osteoporosis and elevated risk of sustaining fragility fracture. Most approved osteoporosis treatments work by decreasing the rate of bone resorption, however, these treatments also......-M and S-G respectively compared to 671 mg/cm3 in vehicle treated OVX and 750 mg/cm3 SHAM rats). Bone strength analysis revealed a significant increase (p...

  18. Calcium currents in a fast-twitch skeletal muscle of the rat

    OpenAIRE

    1983-01-01

    Slow ionic currents were measured in the rat omohyoid muscle with the three-microelectrode voltage-clamp technique. Sodium and delayed rectifier potassium currents were blocked pharmacologically. Under these conditions, depolarizing test pulses elicited an early outward current, followed by a transient slow inward current, followed in turn by a late outward current. The early outward current appeared to be a residual delayed rectifier current. The slow inward current was identified as a calci...

  19. A comparative study of charge movement in rat and frog skeletal muscle fibres.

    Science.gov (United States)

    Hollingworth, S; Marshall, M W

    1981-12-01

    1. The middle of the fibre voltage--clamp technique (Adrian & Marshall, 1977), modified where necessary for electrically short muscle fibres, has been used to measure non-linear charge movements in mammalian fast twitch (rat extensor digitorum longus), mammalian slow twitch (rat soleus) and frog (sartorius) muscles. 2. The maximum amount of charge moved in mammalian fast twitch muscle at 2 degrees C in hypertonic solution, was 3--5 times greater than in slow twitch muscle. The voltage distribution of fast twitch charge was 10--15 mV more positive when compared to slow twitch. 3. In both mammalian muscle types hypertonic Ringer solution negatively shifted the voltage distribution of charge some 6 mV. The steepness of charge moved around mechanical threshold was unaffected by hypertonicity. 4. The amount of charge in frog sartorius fibres at 2 degrees C in hypertonic solution was about half of that in rat fast twitch muscle; the voltage distribution of the frog charge was similar to rat soleus muscle. 5. Warming between 2 and 15 degrees C had no effect on either the amount of steady-state distribution of charge in mammalian or frog muscles. 6. At 2 degrees C, the kinetics of charge movement in fast and slow twitch mammalian muscles were similar and 2--3 times faster than frog muscle at the same temperature. In fast and slow mammalian fibres at 2 degrees C similar times were taken to shift the same fractions of the total amount of charge. The Q10 of charge movement kinetics was between 1.2 and 2.0 in the three muscles studied.

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

    OpenAIRE

    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...

  1. Would Interstitial Fluid Flow be Responsible for Skeletal Maintenance in Tail-Suspended Rats?

    Science.gov (United States)

    Li, Wen-Ting; Huang, Yun-Fei; Sun, Lian-Wen; Luan, Hui-Qin; Zhu, Bao-Zhang; Fan, Yu-Bo

    2017-02-01

    Despite the fast development of manned space flight, the mechanism and countermeasures of weightlessness osteoporosis in astronauts are still within research. It is accepted that unloading has been considered as primary factor, but the precise mechanism is still unclear. Since bone's interstitial fluid flow (IFF) is believed to be significant to nutrient supply and waste metabolism of bone tissue, it may influence bone quality as well. We investigated IFF's variation in different parts of body (included parietal bone, ulna, lumbar, tibia and tailbone) of rats using a tail-suspended (TS) system. Ten female Sprague-Dawley (SD) rats were divided into two groups: control (CON) and tail-suspension (TS) group. And after 21 days' experiment, the rats were injected reactive red to observe lacuna's condition under a confocal laser scanning microscope. The variations of IFF were analyzed by the number and area of lacuna. Volumetric bone mineral density (vBMD) and microarchitecture of bones were evaluated by micro-CT. The correlation coefficients between lacuna's number/area and vBMD were also analyzed. According to our experimental results, a 21 days' tail-suspension could cause a decrease of IFF in lumbar, tibia and tailbone and an increase of IFF in ulna. But in parietal bone, it showed no significant change. The vBMD and microarchitecture parameters also decreased in lumbar and tibia and increased in ulna. But in parietal bone and tailbone, it showed no significant change. And correlation analysis showed significant correlation between vBMD and lacuna's number in lumbar, tibia and ulna. Therefore, IFF decrease may be partly contribute to bone loss in tail-suspended rats, and it should be further investigated.

  2. Effect of pinacidil on norepinephrine- and potassium-induced contractions and membrane potential in rat and human resistance vessels and in rat aorta

    International Nuclear Information System (INIS)

    Videbaek, L.M.; Aalkjaer, C.; Mulvany, M.J.

    1988-01-01

    The effect of pinacidil on contractile responses to norepinephrine, potassium, and membrane potential was examined in rat and human resistance vessels. In some experiments rat aorta was also used. Pinacidil (0.1-30 microM) caused a concentration-dependent relaxation of norepinephrine-induced contractions in all vessels studied. In the same concentration range, pinacidil had only little effect on potassium (125 mM) activated rat mesenteric and femoral resistance vessels. In denervated rat mesenteric resistance vessels, a depolarization with potassium (125 mM) before superimposing a norepinephrine tone markedly diminished the effect of pinacidil. In resting rat mesenteric resistance vessels, pinacidil (1-10 microM) caused a hyperpolarization of 10-15 mV. In rat aorta, pinacidil (10 microM) caused a significant (p less than 0.001) increase in 86 Rb+ efflux rate constant whereas 1 microM had no effect. The results of these experiments indicate that the vasodilating effect may be caused by a hyperpolarization of the vascular smooth muscle cell membrane

  3. The effects of low frequency electrical stimulation on satellite cell activity in rat skeletal muscle during hindlimb suspension

    Directory of Open Access Journals (Sweden)

    Zhang Hong-Yu

    2010-11-01

    Full Text Available Abstract Background The ability of skeletal muscle to grow and regenerate is dependent on resident stem cells called satellite cells. It has been shown that chronic hindlimb unloading downregulates the satellite cell activity. This study investigated the role of low-frequency electrical stimulation on satellite cell activity during a 28 d hindlimb suspension in rats. Results Mechanical unloading resulted in a 44% reduction in the myofiber cross-sectional area as well as a 29% and 34% reduction in the number of myonuclei and myonuclear domains, respectively, in the soleus muscles (P vs the weight-bearing control. The number of quiescent (M-cadherin+, proliferating (BrdU+ and myoD+, and differentiated (myogenin+ satellite cells was also reduced by 48-57% compared to the weight-bearing animals (P P Conclusion This study shows that electrical stimulation partially attenuated the decrease in muscle size and satellite cells during hindlimb unloading. The causal relationship between satellite cell activation and electrical stimulation remain to be established.

  4. Biphasic regulation of development of the high-affinity saxitoxin receptor by innervation in rat skeletal muscle

    International Nuclear Information System (INIS)

    Sherman, S.J.; Catterall, W.A.

    1982-01-01

    Specific binding of 3 H-saxitoxin (STX) was used to quantitate the density of voltage-sensitive sodium channels in developing rat skeletal muscle. In adult triceps surae, a single class of sites with a KD . 2.9 nM and a density of 21 fmol/mg wet wt was detected. The density of these high-affinity sites increased from 2.0 fmol/mg wet wt to the adult value in linear fashion during days 2-25 after birth. Denervation of the triceps surae at day 11 or 17 reduced final saxitoxin receptor site density to 10.4 or 9.2 fmol/mg wet wt, respectively, without changing KD. Denervation of the triceps surae at day 5 did not alter the subsequent development of saxitoxin receptor sites during days 5-9 and accelerated the increase of saxitoxin receptor sites during days 9-13. After day 13, saxitoxin receptor development abruptly ceased and the density of saxitoxin receptor sites declined to 11 fmol/wg wet wt. These results show that the regulation of high-affinity saxitoxin receptor site density by innervation is biphasic. During the first phase, which is independent of continuing innervation, the saxitoxin receptor density increases to 47-57% of the adult level. After day 11, the second phase of development, which is dependent on continuing innervation, gives rise to the adult density of saxitoxin receptors

  5. A General Mathematical Algorithm for Predicting the Course of Unfused Tetanic Contractions of Motor Units in Rat Muscle.

    Directory of Open Access Journals (Sweden)

    Rositsa Raikova

    Full Text Available An unfused tetanus of a motor unit (MU evoked by a train of pulses at variable interpulse intervals is the sum of non-equal twitch-like responses to these stimuli. A tool for a precise prediction of these successive contractions for MUs of different physiological types with different contractile properties is crucial for modeling the whole muscle behavior during various types of activity. The aim of this paper is to develop such a general mathematical algorithm for the MUs of the medial gastrocnemius muscle of rats. For this purpose, tetanic curves recorded for 30 MUs (10 slow, 10 fast fatigue-resistant and 10 fast fatigable were mathematically decomposed into twitch-like contractions. Each contraction was modeled by the previously proposed 6-parameter analytical function, and the analysis of these six parameters allowed us to develop a prediction algorithm based on the following input data: parameters of the initial twitch, the maximum force of a MU and the series of pulses. Linear relationship was found between the normalized amplitudes of the successive contractions and the remainder between the actual force levels at which the contraction started and the maximum tetanic force. The normalization was made according to the amplitude of the first decomposed twitch. However, the respective approximation lines had different specific angles with respect to the ordinate. These angles had different and non-overlapping ranges for slow and fast MUs. A sensitivity analysis concerning this slope was performed and the dependence between the angles and the maximal fused tetanic force normalized to the amplitude of the first contraction was approximated by a power function. The normalized MU contraction and half-relaxation times were approximated by linear functions depending on the normalized actual force levels at which each contraction starts. The normalization was made according to the contraction time of the first contraction. The actual force levels

  6. 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.

  7. 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.

  8. 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.

  9. Effect of Kaiyu Qingwei Granule (开郁清胃颗粒) on Insulin Receptor in Liver and Skeletal Muscular Cell Membrane in Diabetes Mellitus Rats

    Institute of Scientific and Technical Information of China (English)

    LIU Hong-fang (柳红芳); TONG Xiao-lin(仝小林); WANG Qing-guo(王庆国); ZUO Ping-ping(左萍萍); GUO An-chen(郭安臣); LIU Hong-xing(刘红星)

    2003-01-01

    Objective: To investigate the effect of Kaiyu Qingwei granule (KYQWG,开郁清胃颗粒) on the insulin binding capacity of liver and skeletal muscular cell membrane and serum insulin-like growth factor-1 (IGF-1) in streptozotocin-induced diabetic rats. Methods:Rats in four experimental groups were investigated: the control group, the model group, the KYQWG group and the Metformin group. The insulin binding rate (IBR) of liver and skeletal muscular cell membrane was detected by receptor-ligand radiometric method and changes of serum levels of glucose, insulin and IGF-1 were observed before and after 4 weeks of medication. Results: The KYQWG group had a lower blood glucose level and IBR of liver and muscular cell membrane, as compared with those in the model group (P<0.01 or P<0.05), and a higher level of IGF-1 than that in the model group(P<0.01), but had no obvious changes in the serum level of insulin. Conclusion: KYQWG may increase the serum level of IGF-1 in diabetic rats, thus to decrease the insulin resistance at ante-receptor sites and improve the sugar metabolic disturbance in rats with diabetes mellitus.

  10. Mineral and Skeletal Homeostasis Influence the Manner of Bone Loss in Metabolic Osteoporosis due to Calcium-Deprived Diet in Different Sites of Rat Vertebra and Femur

    Directory of Open Access Journals (Sweden)

    Marzia Ferretti

    2015-01-01

    Full Text Available Rats fed calcium-deprived diet develop osteoporosis due to enhanced bone resorption, secondary to parathyroid overactivity resulting from nutritional hypocalcemia. Therefore, rats provide a good experimental animal model for studying bone modelling alterations during biochemical osteoporosis. Three-month-old Sprague-Dawley male rats were divided into 4 groups: (1 baseline, (2 normal diet for 4 weeks, (3 calcium-deprived diet for 4 weeks, and (4 calcium-deprived diet for 4 weeks and concomitant administration of PTH (1-34 40 µg/Kg/day. Histomorphometrical analyses were made on cortical and trabecular bone of lumbar vertebral body as well as of mid-diaphysis and distal metaphysis of femur. In all rats fed calcium-deprived diet, despite the reduction of trabecular number (due to the maintenance of mineral homeostasis, an intense activity of bone deposition occurs on the surface of the few remaining trabeculae (in answering to mechanical stresses and, consequently, to maintain the skeletal homeostasis. Different responses were detected in different sites of cortical bone, depending on their main function in answering mineral or skeletal homeostasis. This study represents the starting point for work-in-progress researches, with the aim of defining in detail timing and manners of evolution and recovery of biochemical osteoporosis.

  11. 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.

  12. Hypoxia in Combination With Muscle Contraction Improves Insulin Action and Glucose Metabolism in Human Skeletal Muscle via the HIF-1α Pathway.

    Science.gov (United States)

    Görgens, Sven W; Benninghoff, Tim; Eckardt, Kristin; Springer, Christian; Chadt, Alexandra; Melior, Anita; Wefers, Jakob; Cramer, Andrea; Jensen, Jørgen; Birkeland, Kåre I; Drevon, Christian A; Al-Hasani, Hadi; Eckel, Jürgen

    2017-11-01

    Skeletal muscle insulin resistance is the hallmark of type 2 diabetes and develops long before the onset of the disease. It is well accepted that physical activity improves glycemic control, but the knowledge on underlying mechanisms mediating the beneficial effects remains incomplete. Exercise is accompanied by a decrease in intramuscular oxygen levels, resulting in induction of HIF-1α. HIF-1α is a master regulator of gene expression and might play an important role in skeletal muscle function and metabolism. Here we show that HIF-1α is important for glucose metabolism and insulin action in skeletal muscle. By using a genome-wide gene expression profiling approach, we identified RAB20 and TXNIP as two novel exercise/HIF-1α-regulated genes in skeletal muscle. Loss of Rab20 impairs insulin-stimulated glucose uptake in human and mouse skeletal muscle by blocking the translocation of GLUT4 to the cell surface. In addition, exercise/HIF-1α downregulates the expression of TXNIP , a well-known negative regulator of insulin action. In conclusion, we are the first to demonstrate that HIF-1α is a key regulator of glucose metabolism in skeletal muscle by directly controlling the transcription of RAB20 and TXNIP These results hint toward a novel function of HIF-1α as a potential pharmacological target to improve skeletal muscle insulin sensitivity. © 2017 by the American Diabetes Association.

  13. Effects of thyroid hormones on calcium contents and 45Ca exchange in rat skeletal muscle

    International Nuclear Information System (INIS)

    Everts, M.E.; Clausen, T.

    1986-01-01

    In 4-wk-old rats, pretreatment with L-triiodothyronine (T3) increased calcium content by 100% and the 30-min 45 Ca uptake by 64% in the soleus, whereas the extensor digitorum longus (EDL) muscle showed no significant change. The stimulation of 45 Ca uptake was resistant to dantrolene and methoxyverapamil (D600) and could not be attributed to altered permeability of the plasma membrane to calcium, but appears to reflect increased net accumulation of calcium in intracellular pools. The stimulating effect of high K0 (20 mM) on 45 Ca uptake was more pronounced in soleus than in EDL and could be suppressed by dantrolene and D600. The results indicate that the effects of T3 on calcium content and 45 Ca exchange are primarily exerted on muscles containing a large proportion of slow-twitch, oxidative fibers. In soleus muscle from hyperthyroid rats the stimulating effects of high K0 on 45 Ca uptake and lactate production were, respectively, 3.4 and 4.5 times larger than in those obtained from controls. These observations further support the earlier proposed idea [C. van Hardeveld and T. Clausen. Am. J. Physiol. 247 (Endocrinol. Metab. 10): E421-E430, 1984] that the metabolic effects of thyroid hormone depend on the availability of cellular as well as extracellular calcium

  14. Effects of thyroid hormones on calcium contents and 45Ca exchange in rat skeletal muscle

    Energy Technology Data Exchange (ETDEWEB)

    Everts, M.E.; Clausen, T.

    1986-09-01

    In 4-wk-old rats, pretreatment with L-triiodothyronine (T3) increased calcium content by 100% and the 30-min /sup 45/Ca uptake by 64% in the soleus, whereas the extensor digitorum longus (EDL) muscle showed no significant change. The stimulation of /sup 45/Ca uptake was resistant to dantrolene and methoxyverapamil (D600) and could not be attributed to altered permeability of the plasma membrane to calcium, but appears to reflect increased net accumulation of calcium in intracellular pools. The stimulating effect of high K0 (20 mM) on /sup 45/Ca uptake was more pronounced in soleus than in EDL and could be suppressed by dantrolene and D600. The results indicate that the effects of T3 on calcium content and /sup 45/Ca exchange are primarily exerted on muscles containing a large proportion of slow-twitch, oxidative fibers. In soleus muscle from hyperthyroid rats the stimulating effects of high K0 on /sup 45/Ca uptake and lactate production were, respectively, 3.4 and 4.5 times larger than in those obtained from controls. These observations further support the earlier proposed idea (C. van Hardeveld and T. Clausen. Am. J. Physiol. 247 (Endocrinol. Metab. 10): E421-E430, 1984) that the metabolic effects of thyroid hormone depend on the availability of cellular as well as extracellular calcium.

  15. Changes in the cholinergic system of rat sciatic nerve and skeletal muscle following suspension induced disuse

    Science.gov (United States)

    Gupta, R. C.; Misulis, K. E.; Dettbarn, W. D.

    1984-01-01

    Muscle disused induced changes in the cholinergic system of sciatic nerve, slow twitch soleus (SOL) and fast twitch extensor digitorum longus (EDL) muscle were studied in rats. Rats with hindlimbs suspended for 2 to 3 weeks showed marked elevation in the activity of choline acetyltransferase (ChAT) in sciatic nerve (38%), in SOL (108%) and in EDL (67%). Acetylcholinesterase (AChE) activity in SOL increased by 163% without changing the molecular forms pattern of 4S, 10S, 12S, and 16S. No significant changes in activity and molecular forms pattern of AChE were seen in EDL or in AChE activity of sciatic nerve. Nicotinic receptor binding of 3H-acetylcholine was increased in both muscles. When measured after 3 weeks of hindlimb suspension the normal distribution of type 1 fibers in SOL was reduced and a corresponding increase in type IIa and IIb fibers is seen. In EDL no significant change in fiber proportion is observed. Muscle activity, such as loadbearing, appears to have a greater controlling influence on the characteristics of the slow twitch SOL muscle than upon the fast twitch EDL muscle.

  16. A robust neuromuscular system protects rat and human skeletal muscle from sarcopenia.

    Science.gov (United States)

    Pannérec, Alice; Springer, Margherita; Migliavacca, Eugenia; Ireland, Alex; Piasecki, Mathew; Karaz, Sonia; Jacot, Guillaume; Métairon, Sylviane; Danenberg, Esther; Raymond, Frédéric; Descombes, Patrick; McPhee, Jamie S; Feige, Jerome N

    2016-04-01

    Declining muscle mass and function is one of the main driv