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Sample records for muscle metaboreceptor stimulation

  1. Acid-sensing ion channels contribute to the metaboreceptor component of the exercise pressor reflex

    OpenAIRE

    McCord, Jennifer L.; Tsuchimochi, Hirotsugu; Kaufman, Marc P.

    2009-01-01

    The exercise pressor reflex is evoked by both mechanical and metabolic stimuli arising in contracting skeletal muscle. Recently, the blockade of acid-sensing ion channels (ASICs) with amiloride and A-316567 attenuated the reflex. Moreover, amiloride had no effect on the mechanoreceptor component of the reflex, prompting us to determine whether ASICs contributed to the metaboreceptor component of the exercise pressor reflex. The metaboreceptor component can be assessed by measuring mean arteri...

  2. Mimicking muscle activity with electrical stimulation

    Science.gov (United States)

    Johnson, Lise A.; Fuglevand, Andrew J.

    2011-02-01

    Functional electrical stimulation is a rehabilitation technology that can restore some degree of motor function in individuals who have sustained a spinal cord injury or stroke. One way to identify the spatio-temporal patterns of muscle stimulation needed to elicit complex upper limb movements is to use electromyographic (EMG) activity recorded from able-bodied subjects as a template for electrical stimulation. However, this requires a transfer function to convert the recorded (or predicted) EMG signals into an appropriate pattern of electrical stimulation. Here we develop a generalized transfer function that maps EMG activity into a stimulation pattern that modulates muscle output by varying both the pulse frequency and the pulse amplitude. We show that the stimulation patterns produced by this transfer function mimic the active state measured by EMG insofar as they reproduce with good fidelity the complex patterns of joint torque and joint displacement.

  3. Leucine stimulation of skeletal muscle protein synthesis

    International Nuclear Information System (INIS)

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

    1986-01-01

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

  4. 21 CFR 890.5860 - Ultrasound and muscle stimulator.

    Science.gov (United States)

    2010-04-01

    ..., muscle spasms, and joint contractures, but not for the treatment of malignancies. The device also passes... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ultrasound and muscle stimulator. 890.5860 Section... Ultrasound and muscle stimulator. (a) Ultrasound and muscle stimulator for use in applying therapeutic deep...

  5. The Effect of Electrical Stimulation in Improving Muscle Tone (Clinical)

    Science.gov (United States)

    Azman, M. F.; Azman, A. W.

    2017-11-01

    Electrical stimulation (ES) and also known as neuromuscular electrical stimulation (NMES) and transcutaneous electrical stimulation (TES) involves the use of electrical current to stimulate the nerves or nerve endings that innervate muscle beneath the skin. Electrical stimulation may be applied superficially on the skin (transcutaneously) or directly into a muscle or muscles (intramuscularly) for the primary purpose of enhancing muscle function. The basic theoretical premise is that if the peripheral nerve can be stimulated, the resulting excitation impulse will be transmitted along the nerve to the motor endplates in the muscle, producing a muscle contraction. In this work, the effect of mere electrical stimulation to the muscle bulk and strength are tested. This paper explains how electrical stimulation can affect the muscle bulk, muscle size, muscle tone, muscle atrophy and muscle strength. The experiment and data collection are performed on 5 subjects and the results obtained are analyzed. This research aims to understand the full potential of electrical stimulation and identifying its possible benefits or disadvantages to the muscle properties. The results indicated that electrical stimulation alone able to improve muscle properties but with certain limits and precautions which might be useful in rehabilitation programme.

  6. Biceps brachii muscle oxygenation in electrical muscle stimulation.

    Science.gov (United States)

    Muthalib, Makii; Jubeau, Marc; Millet, Guillaume Y; Maffiuletti, Nicola A; Ferrari, Marco; Nosaka, Kazunori

    2010-09-01

    The purpose of this study was to compare between electrical muscle stimulation (EMS) and maximal voluntary (VOL) isometric contractions of the elbow flexors for changes in biceps brachii muscle oxygenation (tissue oxygenation index, TOI) and haemodynamics (total haemoglobin volume, tHb = oxygenated-Hb + deoxygenated-Hb) determined by near-infrared spectroscopy (NIRS). The biceps brachii muscle of 10 healthy men (23-39 years) was electrically stimulated at high frequency (75 Hz) via surface electrodes to evoke 50 intermittent (4-s contraction, 15-s relaxation) isometric contractions at maximum tolerated current level (EMS session). The contralateral arm performed 50 intermittent (4-s contraction, 15-s relaxation) maximal voluntary isometric contractions (VOL session) in a counterbalanced order separated by 2-3 weeks. Results indicated that although the torque produced during EMS was approximately 50% of VOL (P<0.05), there was no significant difference in the changes in TOI amplitude or TOI slope between EMS and VOL over the 50 contractions. However, the TOI amplitude divided by peak torque was approximately 50% lower for EMS than VOL (P<0.05), which indicates EMS was less efficient than VOL. This seems likely because of the difference in the muscles involved in the force production between conditions. Mean decrease in tHb amplitude during the contraction phases was significantly (P<0.05) greater for EMS than VOL from the 10th contraction onwards, suggesting that the muscle blood volume was lower in EMS than VOL. It is concluded that local oxygen demand of the biceps brachii sampled by NIRS is similar between VOL and EMS.

  7. Effect of transcutaneous electrical muscle stimulation on muscle volume in patients with septic shock

    DEFF Research Database (Denmark)

    Poulsen, Jesper Brøndum; Møller, Kirsten; Jensen, Claus V

    2011-01-01

    Objective: Intensive care unit admission is associated with muscle wasting and impaired physical function. We investigated the effect of early transcutaneous electrical muscle stimulation on quadriceps muscle volume in patients with septic shock. Design: Randomized interventional study using...

  8. Nonlinear joint angle control for artificially stimulated muscle

    NARCIS (Netherlands)

    Veltink, Petrus H.; Chizeck, Howard J.; Crago, Patrick E.; El-Bialy, Ahmed

    1992-01-01

    Designs of both open- and closed-loop controllers of electrically stimulated muscle that explicitly depend on a nonlinear mathematical model of muscle input-output properties are presented and evaluated. The muscle model consists of three factors: a muscle activation dynamics factor, an angle-torque

  9. Spot light on skeletal muscles: optogenetic stimulation to understand and restore skeletal muscle function.

    Science.gov (United States)

    van Bremen, Tobias; Send, Thorsten; Sasse, Philipp; Bruegmann, Tobias

    2017-08-01

    Damage of peripheral nerves results in paralysis of skeletal muscle. Currently, the only treatment option to restore proper function is electrical stimulation of the innervating nerve or of the skeletal muscles directly. However this approach has low spatial and temporal precision leading to co-activation of antagonistic muscles and lacks cell-type selectivity resulting in pain or discomfort by stimulation of sensible nerves. In contrast to electrical stimulation, optogenetic methods enable spatially confined and cell-type selective stimulation of cells expressing the light sensitive channel Channelrhodopsin-2 with precise temporal control over the membrane potential. Herein we summarize the current knowledge about the use of this technology to control skeletal muscle function with the focus on the direct, non-neuronal stimulation of muscle fibers. The high temporal flexibility of using light pulses allows new stimulation patterns to investigate skeletal muscle physiology. Furthermore, the high spatial precision of focused illumination was shown to be beneficial for selective stimulation of distinct nearby muscle groups. Finally, the cell-type specific expression of the light-sensitive effector proteins in muscle fibers will allow pain-free stimulation and open new options for clinical treatments. Therefore, we believe that direct optogenetic stimulation of skeletal muscles is a very potent method for basic scientists that also harbors several distinct advantages over electrical stimulation to be considered for clinical use in the future.

  10. Effect of transcutaneous electrical muscle stimulation on postoperative muscle mass and protein synthesis

    DEFF Research Database (Denmark)

    Vinge, O; Edvardsen, L; Jensen, F

    1996-01-01

    In an experimental study, 13 patients undergoing major elective abdominal surgery were given postoperative transcutaneous electrical muscle stimulation (TEMS) to the quadriceps femoris muscle on one leg; the opposite leg served as control. Changes in cross-sectional area (CSA) and muscle protein ...... protein synthesis and muscle mass after abdominal surgery and should be evaluated in other catabolic states with muscle wasting.......In an experimental study, 13 patients undergoing major elective abdominal surgery were given postoperative transcutaneous electrical muscle stimulation (TEMS) to the quadriceps femoris muscle on one leg; the opposite leg served as control. Changes in cross-sectional area (CSA) and muscle protein...... synthesis were assessed by computed tomography and ribosome analysis of percutaneous muscle biopsies before surgery and on the sixth postoperative day. The percentage of polyribosomes in the ribosome suspension decreased significantly (P

  11. The optimal stimulation pattern for skeletal muscle is dependent on muscle length

    NARCIS (Netherlands)

    Mela, P.; Veltink, Petrus H.; Huijing, P.A.J.B.M.; Salmons, S.; Jarvis, J.C.

    2002-01-01

    elicited muscle contraction. Such patterns, providing the desired force output with the minimum number of pulses, may reduce muscle fatigue, which has been shown to correlate to the number of pulses delivered. Applications of electrical stimulation to use muscle as a controllable biological actuator

  12. Influence of synchronous and sequential stimulation on muscle fatigue

    NARCIS (Netherlands)

    Thomsen, M.; Thomsen, M.; Veltink, Petrus H.

    1997-01-01

    In acute experiments the sciatic nerve of the rat is electrically stimulated to induce fatigue in the medial Gastrocnemius muscle. Fatigue tests are carried out using intermittent stimulation of different compartments (sequential) or a single compartment (synchronous) of the sciatic nerve. The

  13. Mechanisms limiting glycogen storage in muscle during prolonged insulin stimulation

    DEFF Research Database (Denmark)

    Richter, Erik; Hansen, S A; Hansen, B F

    1988-01-01

    increased muscle glycogen concentrations to maximal values 2, 3, and 3.5 times above normal fed levels in fast-twitch white, slow-twitch red, and fast-twitch red fibers, respectively. Glucose uptake decreased (mean +/- SE) from 34.9 +/- 1.2 mumol.g-1.h-1 at 0 h to 7.5 +/- 0.7 after 7 h of perfusion. During...... compared with initial values. Total muscle water concentration decreased during glycogen loading of the muscles. Mechanisms limiting glycogen storage under maximal insulin stimulation include impaired insulin-stimulated membrane transport of glucose as well as impaired intracellular glucose disposal....

  14. Human skeletal muscle fibroblasts stimulate in vitro myogenesis and in vivo muscle regeneration

    DEFF Research Database (Denmark)

    Mackey, Abigail L; Magnan, Mélanie; Chazaud, Bénédicte

    2017-01-01

    immediately surrounding regenerating muscle fibres. These novel findings indicate an important role for fibroblasts in supporting the regeneration of muscle fibres, potentially through direct stimulation of satellite cell differentiation and fusion, and contribute to understanding of cell-cell cross......-talk during physiological and pathological muscle remodelling. ABSTRACT: Accumulation of skeletal muscle extracellular matrix is an unfavourable characteristic of many muscle diseases, muscle injury and sarcopenia. In addition to the indispensable role satellite cells play in muscle regeneration......, there is emerging evidence in rodents for a regulatory influence on fibroblast activity. However, the influence of fibroblasts on satellite cells and muscle regeneration in humans is unknown. The purpose of this study was to investigate this in vitro and during in vivo regeneration in humans. Following a muscle...

  15. Electrical stimulation counteracts muscle atrophy associated with aging in humans

    Directory of Open Access Journals (Sweden)

    Helmut Kern

    2013-07-01

    Full Text Available Functional and structural muscle decline is a major problem during aging. Our goal was to improve in old subjects quadriceps m. force and mobility functional performances (stair test, chair rise test, timed up and go test with neuromuscular electrical stimulation (9 weeks, 2-3times/week, 20-30 minutes per session. Furthermore we performed histological and biological molecular analyses of vastus lateralis m. biopsies. Our findings demonstrate that electrical stimulation significantly improved mobility functional performancies and muscle histological characteristics and molecular markers.

  16. Electrical Stimulation of Coleopteran Muscle for Initiating Flight.

    Science.gov (United States)

    Choo, Hao Yu; Li, Yao; Cao, Feng; Sato, Hirotaka

    2016-01-01

    Some researchers have long been interested in reconstructing natural insects into steerable robots or vehicles. However, until recently, these so-called cyborg insects, biobots, or living machines existed only in science fiction. Owing to recent advances in nano/micro manufacturing, data processing, and anatomical and physiological biology, we can now stimulate living insects to induce user-desired motor actions and behaviors. To improve the practicality and applicability of airborne cyborg insects, a reliable and controllable flight initiation protocol is required. This study demonstrates an electrical stimulation protocol that initiates flight in a beetle (Mecynorrhina torquata, Coleoptera). A reliable stimulation protocol was determined by analyzing a pair of dorsal longitudinal muscles (DLMs), flight muscles that oscillate the wings. DLM stimulation has achieved with a high success rate (> 90%), rapid response time (cyborg insects or biobots.

  17. Catechins activate muscle stem cells by Myf5 induction and stimulate muscle regeneration.

    Science.gov (United States)

    Kim, A Rum; Kim, Kyung Min; Byun, Mi Ran; Hwang, Jun-Ha; Park, Jung Il; Oh, Ho Taek; Kim, Hyo Kyeong; Jeong, Mi Gyeong; Hwang, Eun Sook; Hong, Jeong-Ho

    2017-07-22

    Muscle weakness is one of the most common symptoms in aged individuals and increases risk of mortality. Thus, maintenance of muscle mass is important for inhibiting aging. In this study, we investigated the effect of catechins, polyphenol compounds in green tea, on muscle regeneration. We found that (-)-epicatechin gallate (ECG) and (-)-epigallocatechin-3-gallate (EGCG) activate satellite cells by induction of Myf5 transcription factors. For satellite cell activation, Akt kinase was significantly induced after ECG treatment and ECG-induced satellite cell activation was blocked in the presence of Akt inhibitor. ECG also promotes myogenic differentiation through the induction of myogenic markers, including Myogenin and Muscle creatine kinase (MCK), in satellite and C2C12 myoblast cells. Finally, EGCG administration to mice significantly increased muscle fiber size for regeneration. Taken together, the results suggest that catechins stimulate muscle stem cell activation and differentiation for muscle regeneration. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Human skeletal muscle fibroblasts stimulate in vitro myogenesis and in vivo muscle regeneration.

    Science.gov (United States)

    Mackey, Abigail L; Magnan, Mélanie; Chazaud, Bénédicte; Kjaer, Michael

    2017-08-01

    Accumulation of skeletal muscle extracellular matrix is an unfavourable characteristic of many muscle diseases, muscle injury and sarcopenia. The extent of cross-talk between fibroblasts, as the source of matrix protein, and satellite cells in humans is unknown. We studied this in human muscle biopsies and cell-culture studies. We observed a strong stimulation of myogenesis by human fibroblasts in cell culture. In biopsies collected 30 days after a muscle injury protocol, fibroblast number increased to four times control levels, where fibroblasts were found to be preferentially located immediately surrounding regenerating muscle fibres. These novel findings indicate an important role for fibroblasts in supporting the regeneration of muscle fibres, potentially through direct stimulation of satellite cell differentiation and fusion, and contribute to understanding of cell-cell cross-talk during physiological and pathological muscle remodelling. Accumulation of skeletal muscle extracellular matrix is an unfavourable characteristic of many muscle diseases, muscle injury and sarcopenia. In addition to the indispensable role satellite cells play in muscle regeneration, there is emerging evidence in rodents for a regulatory influence on fibroblast activity. However, the influence of fibroblasts on satellite cells and muscle regeneration in humans is unknown. The purpose of this study was to investigate this in vitro and during in vivo regeneration in humans. Following a muscle injury protocol in young healthy men (n = 7), the number of fibroblasts (TCF7L2+), satellite cells (Pax7+), differentiating myogenic cells (myogenin+) and regenerating fibres (neonatal/embryonic myosin+) was determined from biopsy cross-sections. Fibroblasts and myogenic precursor cells (MPCs) were also isolated from human skeletal muscle (n = 4) and co-cultured using different cell ratios, with the two cell populations either in direct contact with each other or separated by a permeable

  19. An Implanted, Stimulated Muscle Powered Piezoelectric Generator

    Science.gov (United States)

    Lewandowski, Beth; Gustafson, Kenneth; Kilgore, Kevin

    2007-01-01

    A totally implantable piezoelectric generator system able to harness power from electrically activated muscle could be used to augment the power systems of implanted medical devices, such as neural prostheses, by reducing the number of battery replacement surgeries or by allowing periods of untethered functionality. The features of our generator design are no moving parts and the use of a portion of the generated power for system operation and regulation. A software model of the system has been developed and simulations have been performed to predict the output power as the system parameters were varied within their constraints. Mechanical forces that mimic muscle forces have been experimentally applied to a piezoelectric generator to verify the accuracy of the simulations and to explore losses due to mechanical coupling. Depending on the selection of system parameters, software simulations predict that this generator concept can generate up to approximately 700 W of power, which is greater than the power necessary to drive the generator, conservatively estimated to be 50 W. These results suggest that this concept has the potential to be an implantable, self-replenishing power source and further investigation is underway.

  20. Wanding Through Space: Interactive Calibration for Electric Muscle Stimulation

    DEFF Research Database (Denmark)

    Pohl, Henning; Hornbæk, Kasper; Knibbe, Jarrod

    2018-01-01

    Electric Muscle Stimulation (EMS) has emerged as an interaction paradigm for HCI. It has been used to confer object affordance, provide walking directions, and assist with sketching. However, the electrical signals used for EMS are multi-dimensional and require expert calibration before use...

  1. 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

  2. Electrical Stimulation of Coleopteran Muscle for Initiating Flight.

    Directory of Open Access Journals (Sweden)

    Hao Yu Choo

    Full Text Available Some researchers have long been interested in reconstructing natural insects into steerable robots or vehicles. However, until recently, these so-called cyborg insects, biobots, or living machines existed only in science fiction. Owing to recent advances in nano/micro manufacturing, data processing, and anatomical and physiological biology, we can now stimulate living insects to induce user-desired motor actions and behaviors. To improve the practicality and applicability of airborne cyborg insects, a reliable and controllable flight initiation protocol is required. This study demonstrates an electrical stimulation protocol that initiates flight in a beetle (Mecynorrhina torquata, Coleoptera. A reliable stimulation protocol was determined by analyzing a pair of dorsal longitudinal muscles (DLMs, flight muscles that oscillate the wings. DLM stimulation has achieved with a high success rate (> 90%, rapid response time (< 1.0 s, and small variation (< 0.33 s; indicating little habituation. Notably, the stimulation of DLMs caused no crucial damage to the free flight ability. In contrast, stimulation of optic lobes, which was earlier demonstrated as a successful flight initiation protocol, destabilized the beetle in flight. Thus, DLM stimulation is a promising secure protocol for inducing flight in cyborg insects or biobots.

  3. Automatic Calibration of High Density Electric Muscle Stimulation

    DEFF Research Database (Denmark)

    Knibbe, Jarrod; Strohmeier, Paul; Boring, Sebastian

    2017-01-01

    . (2) EMS requires time consuming, expert calibration -- confining these interaction techniques to the lab. EMS arrays have been shown to increase stimulation resolution, but as calibration complexity increases exponentially as more electrodes are used, we require heuristics or automated procedures......Electric muscle stimulation (EMS) can enable mobile force feedback, support pedestrian navigation, or confer object affordances. To date, however, EMS is limited by two interlinked problems. (1) EMS is low resolution -- achieving only coarse movements and constraining opportunities for exploration...... for successful calibration. We explore the feasibility of using electromyography (EMG) to auto-calibrate high density EMS arrays. We determine regions of muscle activity during human-performed gestures, to inform stimulation patterns for EMS-performed gestures. We report on a study which shows that auto...

  4. Myoelectric stimulation on peroneal muscles resists simulated ankle sprain motion.

    Science.gov (United States)

    Fong, Daniel Tik-Pui; Chu, Vikki Wing-Shan; Chan, Kai-Ming

    2012-07-26

    The inadequate reaction time of the peroneal muscles in response to an incorrect foot contact event has been proposed as one of the etiological factors contributing to ankle joint inversion injury. Thus, the current study aimed to investigate the efficacy of a myoelectric stimulation applied to the peroneal muscles in the prevention of a simulated ankle inversion trauma. Ten healthy male subjects performed simulated inversion and supination tests on a pair of mechanical sprain simulators. An electrical signal was delivered to the peroneal muscles of the subjects through a pair of electrode pads. The start of the stimulus was synchronized with the drop of the sprain simulator's platform. In order to determine the maximum delay time which the stimulus could still resist the simulated ankle sprain motion, different delay time were test (0, 5, 10, and 15ms). Together with the control trial (no stimulus), there were 5 testing conditions for both simulated inversion and supination test. The effect was quantified by the drop in maximum ankle tilting angle and angular velocity, as determined by a motion analysis system with a standard laboratory procedure. Results showed that the myoelectric stimulation was effective in all conditions except the one with myoelectric stimulus delayed for 15ms in simulated supination test. It is concluded that myoelectric stimulation on peroneal muscles could resist an ankle spraining motion. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. ELECTRICAL MUSCLE STIMULATION (EMS IMPLEMENTATION IN EXPLOSIVE STRENGTH DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    Zoran Đokić

    2013-07-01

    Full Text Available Electrical muscle stimulation (EMS, is also known as neuromuscular electrical stimulation (NMES may be used for therapeutic purposes and training. EMS is causing muscle contractions via electrical impulses. The survey was conducted as a case study. The study was conducted on subject of 3 male of different ages. The study lasted 4 weeks, and the respondents have not used any type of training or activity, which would affect the development of explosive strength of the lower extremities. Electrical stimulation was performed in the evening, every other day, with COMPEX mi sport apparatus (Medical SA - All rights reserved - 07/06 - Art. 885,616 - V.2 model. In 4 week period, a total of 13 treatments were performed on selected muscle groups - quadriceps femoris and gastrocnemius. Program of plyometric training (Plyometric (28 min per treatment, for each muscle group were applied. The main objective of this study was to quantify and compare explosive leg strength, using different vertical jump protocols, before and after the EMS program. The initial and final testing was conducted in the laboratory of the Faculty of Sport and Tourism in Novi Sad, on the contact plate AXON JUMP (Bioingeniería Deportiva, VACUMED, 4538 Westinghouse Street Ventura, CA 93 003 under identical conditions. In all three of the respondents indicated an increase in vertical jump in all applied protocols.

  6. Paired associative stimulation targeting the tibialis anterior muscle using either mono or biphasic transcranial magnetic stimulation

    DEFF Research Database (Denmark)

    Mrachacz-Kersting, Natalie; Stevenson, Andrew James Thomas

    2017-01-01

    Paired associative stimulation (PAS) protocols induce plastic changes within the motor cortex. The objectives of this study were to investigate PAS effects targeting the tibialis anterior (TA) muscle using a biphasic transcranial magnetic stimulation (TMS) pulse form and, to determine whether...... a reduced intensity of this pulse would lead to significant changes as has been reported for hand muscles using a monophasic TMS pulse. Three interventions were investigated: (1) suprathreshold PAbi-PAS (n = 11); (2) suprathreshold PAmono-PAS (n = 11) where PAS was applied using a biphasic or monophasic......% for subthreshold PAbi-PAS. PAS using a biphasic pulse form at subthreshold intensities induces similar effects to conventional PAS....

  7. Mechanisms limiting glycogen storage in muscle during prolonged insulin stimulation

    International Nuclear Information System (INIS)

    Richter, E.A.; Hansen, S.A.; Hansen, B.F.

    1988-01-01

    The extent to which muscle glycogen concentrations can be increased during exposure to maximal insulin concentrations and abundant glucose was investigated in the isolated perfused rat hindquarter preparation. Perfusion for 7 h in the presence of 20,000 μU/ml insulin and 11-13 mM glucose increased muscle glycogen concentrations to maximal values 2, 3, and 3.5 times above normal fed levels in fast-twitch white, slow-twitch red, and fast-twitch red fibers, respectively. Glucose uptake decreased from 34.9 μmol·g -1 ·h -1 at 0 h to 7.5 after 7 h of perfusion. During the perfusion muscle glycogen synthase activity decreased and free intracellular glucose and glucose 6-phosphate increased indicating that glucose disposal was impaired. However, glucose transport as measured by the uptake of 3-O-[ 14 C]methyl-D-glucose was also markedly decreased after 5 and 7 h of perfusion compared with initial values. Total muscle water concentration decreased during glycogen loading of the muscles. Mechanisms limiting glycogen storage under maximal insulin stimulation include impaired insulin-stimulated membrane transport of glucose as well as impaired intracellular glucose disposal

  8. Kinesthetic illusions attenuate experimental muscle pain, as do muscle and cutaneous stimulation.

    Science.gov (United States)

    Gay, André; Aimonetti, Jean-Marc; Roll, Jean-Pierre; Ribot-Ciscar, Edith

    2015-07-30

    In the present study, muscle pain was induced experimentally in healthy subjects by administrating hypertonic saline injections into the tibialis anterior (TA) muscle. We first aimed at comparing the analgesic effects of mechanical vibration applied to either cutaneous or muscle receptors of the TA or to both types simultaneously. Secondly, pain alleviation was compared in subjects in whom muscle tendon vibration evoked kinesthetic illusions of the ankle joint. Muscle tendon vibration, which primarily activated muscle receptors, reduced pain intensity by 30% (p<0.01). In addition, tangential skin vibration reduced pain intensity by 33% (p<0.01), primarily by activating cutaneous receptors. Concurrently stimulating both sensory channels induced stronger analgesic effects (-51%, p<0.01), as shown by the lower levels of electrodermal activity. The strongest analgesic effects of the vibration-induced muscle inputs occurred when illusory movements were perceived (-38%, p=0.01). The results suggest that both cutaneous and muscle sensory feedback reduce muscle pain, most likely via segmental and supraspinal processes. Further clinical trials are needed to investigate these new methods of muscle pain relief. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Stimulation of aortic smooth muscle cell mitogenesis by serotonin

    International Nuclear Information System (INIS)

    Nemecek, G.M.; Coughlin, S.R.; Handley, D.A.; Moskowitz, M.A.

    1986-01-01

    Bovine aortic smooth muscle cells in vitro responded to 1 nM to 10 μM serotonin with increased incorporation of [ 3 H]thymidine into DNA. The mitogenic effect of serotonin was half-maximal at 80 nM and maximal above 1 μM. At a concentration of 1 μM, serotonin stimulated smooth muscle cell mitogenesis to the same extent as human platelet-derived growth factor (PDGF) at 12 ng/ml. Tryptamine was ≅ 1/10th as potent as serotonin as a mitogen for smooth muscle cells. Other indoles that are structurally related to serotonin (D- and L-tryptophan, 5-hydroxy-L-tryptophan, N-acetyl-5-hydroxytryptamine, melatonin, 5-hydroxyindoleacetic acid, and 5-hydroxytryptophol) and quipazine were inactive. The stimulatory effect of serotonin on smooth muscle cell DNA synthesis required prolonged (20-24 hr) exposure to the agonist and was attenuated in the presence of serotonin D receptor antagonists. When smooth muscle cells were incubated with submaximal concentrations of serotonin and PDGF, synergistic rather than additive mitogenic responses were observed. These data indicate that serotonin has a significant mitogenic effect on smooth muscle cells in vitro, which appears to be mediated by specific plasma membrane receptors

  10. Recovery Effect of the Muscle Fatigue by the Magnetic Stimulation

    Science.gov (United States)

    Uchida, Kousuke; Nuruki, Atsuo; Tsujimura, Sei-Ichi; Tamari, Youzou; Yunokuchi, Kazutomo

    The purpose of this study is to investigate the effect of magnetic stimulation for muscle fatigue. The six healthy subjects participated in the experiment with the repetition grasp using a hand dynamometer. The measurement of EMG (electromyography) and MMG (mechanomyography) is performed on the left forearm. All subjects performed MVC (maximum voluntary contraction), and repeated exercise in 80%MVC after the MVC measurement. The repetition task was entered when display muscular strength deteriorated. We used an EMG and MMG for the measurement of the muscle fatigue. Provided EMG and MMG waves were calculated integral calculus value (iEMG, and iMMG). The result of iEMG and iMMG were divided by muscular strength, because we calculate integral calculus value per the unit display muscular strength. The result of our study, we found recovery effect by the magnetic stimulation in voluntarily muscular strength and iEMG. However, we can not found in a figure of iMMG.

  11. Functional Neuromuscular Stimulation Controlled by Surface Electromyographic Signals Produced by Volitional Activation of the Same Muscle

    DEFF Research Database (Denmark)

    Sennels, Søren; Biering-Sørensen, Fin; Andersen, Ole Trier

    1997-01-01

    In order to use the volitional electromyography (EMG) as a control signal for the stimulation of the same muscle, it is necessary to eliminate the stimulation artifacts and the muscle responses caused by the stimulation. The stimulation artifacts, caused by the electric field in skin and tissue...

  12. Evidence of skeletal muscle damage following electrically stimulated isometric muscle contractions in humans

    DEFF Research Database (Denmark)

    Mackey, Abigail; Bojsen-Moller, Jens; Qvortrup, Klaus

    2008-01-01

    and desmin-negative staining in a small percentage of myofibers in five and four individuals, respectively. z-Line disruption was evident at varying magnitudes in all subjects and displayed a trend toward a positive correlation (r = 0.73, P = 0.0663) with the force produced by stimulation. Increased muscle...

  13. Mechanical stimulation improves tissue-engineered human skeletal muscle

    Science.gov (United States)

    Powell, Courtney A.; Smiley, Beth L.; Mills, John; Vandenburgh, Herman H.

    2002-01-01

    Human bioartificial muscles (HBAMs) are tissue engineered by suspending muscle cells in collagen/MATRIGEL, casting in a silicone mold containing end attachment sites, and allowing the cells to differentiate for 8 to 16 days. The resulting HBAMs are representative of skeletal muscle in that they contain parallel arrays of postmitotic myofibers; however, they differ in many other morphological characteristics. To engineer improved HBAMs, i.e., more in vivo-like, we developed Mechanical Cell Stimulator (MCS) hardware to apply in vivo-like forces directly to the engineered tissue. A sensitive force transducer attached to the HBAM measured real-time, internally generated, as well as externally applied, forces. The muscle cells generated increasing internal forces during formation which were inhibitable with a cytoskeleton depolymerizer. Repetitive stretch/relaxation for 8 days increased the HBAM elasticity two- to threefold, mean myofiber diameter 12%, and myofiber area percent 40%. This system allows engineering of improved skeletal muscle analogs as well as a nondestructive method to determine passive force and viscoelastic properties of the resulting tissue.

  14. Muscle oxygenation of vastus lateralis and medialis muscles during alternating and pulsed current electrical stimulation.

    Science.gov (United States)

    Aldayel, Abdulaziz; Muthalib, Makii; Jubeau, Marc; McGuigan, Michael; Nosaka, Kazunori

    2011-05-01

    This study compared between alternating and pulsed current electrical muscle stimulation (EMS) for muscle oxygenation and blood volume during isometric contractions. Nine healthy men (23-48 years) received alternating current EMS (2500 Hz) modulated at 75 Hz on the knee extensors of one leg, and pulsed current EMS (75 Hz) for the other leg separated by 2 weeks in a randomised, counter-balanced order. Pulse duration (400 μs), on-off ratio (5-15 s) and other stimulation parameters were matched between conditions and 30 isometric contractions were induced at the knee joint angle of 100° (0° full extension). Changes in tissue oxygenation index (∆TOI) and total hemoglobin volume (∆tHb) of vastus lateralis and medialis muscles over 30 contractions were assessed by a near-infrared spectroscopy, and were compared between conditions by a two-way repeated measures ANOVA. Peak torque produced during EMS increased over 30 contractions in response to the increase in the stimulation intensity for pulsed current, but not for the alternating current EMS. The torque during each isometric contraction was less stable in alternating than pulsed current EMS. The changes in ∆TOI amplitude during relaxation phases and ∆tHb amplitude were not significantly different between conditions. However, the decreases in ∆TOI amplitude during contraction phases from baseline were significantly (P < 0.05) greater for the pulsed current than alternating current from the 18th contraction (-15.6 ± 2.3 vs. -8.9 ± 1.8%) to 30th contraction (-10.7 ± 1.8 vs. -4.8 ± 1.5%). These results suggest that the muscles were less activated in the alternating current EMS when compared with the pulsed current EMS.

  15. Muscle fiber type specific induction of slow myosin heavy chain 2 gene expression by electrical stimulation

    International Nuclear Information System (INIS)

    Crew, Jennifer R.; Falzari, Kanakeshwari; DiMario, Joseph X.

    2010-01-01

    Vertebrate skeletal muscle fiber types are defined by a broad array of differentially expressed contractile and metabolic protein genes. The mechanisms that establish and maintain these different fiber types vary throughout development and with changing functional demand. Chicken skeletal muscle fibers can be generally categorized as fast and fast/slow based on expression of the slow myosin heavy chain 2 (MyHC2) gene in fast/slow muscle fibers. To investigate the cellular and molecular mechanisms that control fiber type formation in secondary or fetal muscle fibers, myoblasts from the fast pectoralis major (PM) and fast/slow medial adductor (MA) muscles were isolated, allowed to differentiate in vitro, and electrically stimulated. MA muscle fibers were induced to express the slow MyHC2 gene by electrical stimulation, whereas PM muscle fibers did not express the slow MyHC2 gene under identical stimulation conditions. However, PM muscle fibers did express the slow MyHC2 gene when electrical stimulation was combined with inhibition of inositol triphosphate receptor (IP3R) activity. Electrical stimulation was sufficient to increase nuclear localization of expressed nuclear-factor-of-activated-T-cells (NFAT), NFAT-mediated transcription, and slow MyHC2 promoter activity in MA muscle fibers. In contrast, both electrical stimulation and inhibitors of IP3R activity were required for these effects in PM muscle fibers. Electrical stimulation also increased levels of peroxisome-proliferator-activated receptor-γ co-activator-1 (PGC-1α) protein in PM and MA muscle fibers. These results indicate that MA muscle fibers can be induced by electrical stimulation to express the slow MyHC2 gene and that fast PM muscle fibers are refractory to stimulation-induced slow MyHC2 gene expression due to fast PM muscle fiber specific cellular mechanisms involving IP3R activity.

  16. Chronic Stimulation-Induced Changes in the Rodent Thyroarytenoid Muscle

    Science.gov (United States)

    McMullen, Colleen A.; Butterfield, Timothy A.; Dietrich, Maria; Andreatta, Richard D.; Andrade, Francisco H.; Fry, Lisa; Stemple, Joseph C.

    2011-01-01

    Purpose: Therapies for certain voice disorders purport principles of skeletal muscle rehabilitation to increase muscle mass, strength, and endurance. However, applicability of limb muscle rehabilitation to the laryngeal muscles has not been tested. In this study, the authors examined the feasibility of the rat thyroarytenoid muscle to remodel as a…

  17. Sensitivity of vertical jumping performance to changes in muscle stimulation onset times: a simulation study

    NARCIS (Netherlands)

    Bobbert, M.F.; van Zandwijk, J.P.

    1999-01-01

    The effect of muscle stimulation dynamics on the sensitivity of jumping achievement to variations in timing of muscle stimulation onsets was investigated. Vertical squat jumps were simulated using a forward dynamic model of the human musculoskeletal system. The model calculates the motion of body

  18. Glycogen depletion and resynthesis during 14 days of chronic low-frequency stimulation of rabbit muscle

    DEFF Research Database (Denmark)

    Prats, C; Bernal, C; Cadefau, J A

    2002-01-01

    Electro-stimulation alters muscle metabolism and the extent of this change depends on application intensity and duration. The effect of 14 days of chronic electro-stimulation on glycogen turnover and on the regulation of glycogen synthase in fast-twitch muscle was studied. The results showed that...

  19. Paired Associative Stimulation Targeting the Tibialis Anterior Muscle using either Mono or Biphasic Transcranial Magnetic Stimulation

    Directory of Open Access Journals (Sweden)

    Natalie Mrachacz-Kersting

    2017-04-01

    Full Text Available Paired associative stimulation (PAS protocols induce plastic changes within the motor cortex. The objectives of this study were to investigate PAS effects targeting the tibialis anterior (TA muscle using a biphasic transcranial magnetic stimulation (TMS pulse form and, to determine whether a reduced intensity of this pulse would lead to significant changes as has been reported for hand muscles using a monophasic TMS pulse. Three interventions were investigated: (1 suprathreshold PAbi-PAS (n = 11; (2 suprathreshold PAmono-PAS (n = 11 where PAS was applied using a biphasic or monophasic pulse form at 120% resting motor threshold (RMT; (3 subthreshold PAbi-PAS (n = 10 where PAS was applied as for (1 at 95% active motor threshold (AMT. The peak-to-peak motor evoked potentials (MEPs were quantified prior to, immediately following, and 30 min after the cessation of the intervention. TA MEP size increased significantly for all interventions immediately post (61% for suprathreshold PAbi-PAS, 83% for suprathreshold PAmono-PAS, 55% for subthreshold PAbi-PAS and 30 min after the cessation of the intervention (123% for suprathreshold PAbi-PAS, 105% for suprathreshold PAmono-PAS, 80% for subthreshold PAbi-PAS. PAS using a biphasic pulse form at subthreshold intensities induces similar effects to conventional PAS.

  20. 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...

  1. Stretch-stimulated glucose transport in skeletal muscle is regulated by Rac1.

    Science.gov (United States)

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

    2015-02-01

    Rac1 regulates stretch-stimulated (i.e. mechanical stress) glucose transport in muscle. Actin depolymerization decreases stretch-induced glucose transport in skeletal muscle. Rac1 is a required part of the mechanical stress-component of the contraction-stimulus to glucose transport in skeletal muscle. An alternative to the canonical insulin signalling pathway for glucose transport is muscle contraction/exercise. Mechanical stress is an integrated part of the muscle contraction/relaxation cycle, and passive stretch stimulates muscle glucose transport. However, the signalling mechanism regulating stretch-stimulated glucose transport is not well understood. We recently reported that the actin cytoskeleton regulating GTPase, Rac1, was activated in mouse muscle in response to stretching. Rac1 is a regulator of contraction- and insulin-stimulated glucose transport, however, its role in stretch-stimulated glucose transport and signalling is unknown. We therefore investigated whether stretch-induced glucose transport in skeletal muscle required Rac1 and the actin cytoskeleton. We used muscle-specific inducible Rac1 knockout mice as well as pharmacological inhibitors of Rac1 and the actin cytoskeleton in isolated soleus and extensor digitorum longus muscles. In addition, the role of Rac1 in contraction-stimulated glucose transport during conditions without mechanical load on the muscles was evaluated in loosely hanging muscles and muscles in which cross-bridge formation was blocked by the myosin ATPase inhibitors BTS and Blebbistatin. Knockout as well as pharmacological inhibition of Rac1 reduced stretch-stimulated glucose transport by 30-50% in soleus and extensor digitorum longus muscle. The actin depolymerizing agent latrunculin B similarly decreased glucose transport in response to stretching by 40-50%. Rac1 inhibition reduced contraction-stimulated glucose transport by 30-40% in tension developing muscle but did not affect contraction-stimulated glucose transport in

  2. Effect of electrical muscle stimulation on prevention of ICU acquired ...

    African Journals Online (AJOL)

    Hassan Abdelaziz Abu-Khaber

    2013-04-19

    Apr 19, 2013 ... shown to increase after an EMS session in rat skeletal muscles.10, ... output, and therefore affect the skeletal muscle metabolism .... Grade 1 No active range of motion & palpable muscle contraction. Grade 0 No active range of motion & no palpable muscle contraction. Table 1 Functions assessed in MRCS.

  3. The influence of strenuous muscle stimulation on the menarche.

    Science.gov (United States)

    Yabuuchi, F; Ichikawa, Y; Arakawa, M; Chiba, G

    1984-03-01

    Nowadays, the average age at which menarche begins is lowering by three to four years every century, that is, four months every decade, according to both Japanese, and European and American annual changes of the average age. It emerged that the menarche shows a tendency to occur later in female gymnasts, because of the influence of strenuous muscle stimulation, and the fact that a higher level of technic is required in gymnastic games each year. These conclusions have been drawn from replies submitted to a questionnaire distributed among a relatively small number of gymnasts who participated in the competitions including the Inter High School Championship and the World Cup Championship. For example, at the age of 14, the percentage of women who had menstruated is almost 100% among women in general, but only 24% among World Cup Championship gymnasts, the average age at menarche of the latter being later than that of the former by as many as 3 years. At the age of 16, the percentage of women who had menstruated is 100% among women in general, but on the other hand, it is only 60% among World Cup Championship gymnasts, in other words, only a low percentage of women, of the latter group, had menstruated. Finally in our study, we established that the age at menarche of gymnasts is three or five years later than that of women in general. From our study, we concluded that the excessive burden imposed on muscles might cause an abnormal menstrual cycle, and the influence on menstruation would be considerable.

  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

    2013-04-01

    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.

  5. Effect of glycogen synthase overexpression on insulin-stimulated muscle glucose uptake and storage.

    Science.gov (United States)

    Fogt, Donovan L; Pan, Shujia; Lee, Sukho; Ding, Zhenping; Scrimgeour, Angus; Lawrence, John C; Ivy, John L

    2004-03-01

    Insulin-stimulated muscle glucose uptake is inversely associated with the muscle glycogen concentration. To investigate whether this association is a cause and effect relationship, we compared insulin-stimulated muscle glucose uptake in noncontracted and postcontracted muscle of GSL3-transgenic and wild-type mice. GSL3-transgenic mice overexpress a constitutively active form of glycogen synthase, which results in an abundant storage of muscle glycogen. Muscle contraction was elicited by in situ electrical stimulation of the sciatic nerve. Right gastrocnemii from GSL3-transgenic and wild-type mice were subjected to 30 min of electrical stimulation followed by hindlimb perfusion of both hindlimbs. Thirty minutes of contraction significantly reduced muscle glycogen concentration in wild-type (49%) and transgenic (27%) mice, although transgenic mice retained 168.8 +/- 20.5 micromol/g glycogen compared with 17.7 +/- 2.6 micromol/g glycogen for wild-type mice. Muscle of transgenic and wild-type mice demonstrated similar pre- (3.6 +/- 0.3 and 3.9 +/- 0.6 micromol.g(-1).h(-1) for transgenic and wild-type, respectively) and postcontraction (7.9 +/- 0.4 and 7.0 +/- 0.4 micromol.g(-1).h(-1) for transgenic and wild-type, respectively) insulin-stimulated glucose uptakes. However, the [14C]glucose incorporated into glycogen was greater in noncontracted (151%) and postcontracted (157%) transgenic muscle vs. muscle of corresponding wild-type mice. These results indicate that glycogen synthase activity is not rate limiting for insulin-stimulated glucose uptake in skeletal muscle and that the inverse relationship between muscle glycogen and insulin-stimulated glucose uptake is an association, not a cause and effect relationship.

  6. Human skeletal muscle fibroblasts stimulate in vitro myogenesis and in vivo muscle regeneration

    DEFF Research Database (Denmark)

    Mackey, Abigail L.; Magnan, Mélanie; Chazaud, Bénédicte

    2017-01-01

    Accumulation of skeletal muscle extracellular matrix is an unfavourable characteristic of many muscle diseases, muscle injury and sarcopenia. In addition to the indispensable role satellite cells play in muscle regeneration, there is emerging evidence in rodents for a regulatory influence...

  7. 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...

  8. Functional Neuromuscular Stimulation Controlled by Surface Electromyographic Signals Produced by the Volitional Activation of the Same Muscle:

    DEFF Research Database (Denmark)

    Sennels, Søren; Fin, Biering-Sørensen; Andersen, Ole Trier

    1997-01-01

    Using the voluntary EMG as a control signal for the stimulation of the same muscle necessitates elimination of stimulus artifacts and the muscle response caused by the stimulation. The stimulus artifacts are easily eliminated by shutting down the amplifier during stimulation. The muscle response ...

  9. Immunohistochemical and Morphofunctional Studies of Skeletal Muscle Tissues with Electric Nerve Stimulation by In Vivo Cryotechnique

    International Nuclear Information System (INIS)

    Fukasawa, Yuki; Ohno, Nobuhiko; Saitoh, Yurika; Saigusa, Takeshi; Arita, Jun; Ohno, Shinichi

    2015-01-01

    In this study, morphological and immunohistochemical alterations of skeletal muscle tissues during persistent contraction were examined by in vivo cryotechnique (IVCT). Contraction of gastrocnemius muscles was induced by sciatic nerve stimulation. The IVCT was performed immediately, 3 min or 10 min after the stimulation start. Prominent ripples of muscle fibers or wavy deformation of sarcolemma were detected immediately after the stimulation, but they gradually diminished to normal levels during the stimulation. The relative ratio of sarcomere and A band lengths was the highest in the control group, but it immediately decreased to the lowest level and then gradually recovered at 3 min or 10 min. Although histochemical intensity of PAS reaction was almost homogeneous in muscle tissues of the control group or immediately after the stimulation, it decreased at 3 min or 10 min. Serum albumin was immunolocalized as dot-like patterns within some muscle fibers at 3 min stimulation. These patterns became more prominent at 10 min, and the dots got larger and saccular in some sarcoplasmic regions. However, IgG1 and IgM were immunolocalized in blood vessels under nerve stimulation conditions. Therefore, IVCT was useful to capture the morphofunctional and metabolic changes of heterogeneous muscle fibers during the persistent contraction

  10. Modifications of baropodograms after transcutaneous electric stimulation of the abductor hallucis muscle in humans standing erect.

    Science.gov (United States)

    Gaillet, Jean-Claude; Biraud, Jean-Claude; Bessou, Monique; Bessou, Paul

    2004-12-01

    Objective data on abductor hallucis muscle biomechanical function in the loaded foot (subject standing erect on both legs) are unavailable. To evaluate the effects of electrical stimulation of the abductor hallucis muscle in the loaded foot on the change of plantar pressures, as measured by digital baropodograms. Six indices were defined to compare baropodograms. The abductor hallucis muscle in 1 foot was subjected to transcutaneous electrical stimulation (20 min) while the subject was standing erect on the floor. Baropodograms were recorded before, immediately thereafter, then 15 days and 2 months later. Differences between baropodogram indices were subjected to one-way anova. Electrical abductor hallucis muscle stimulation induced, on the stimulation side, a post-contraction state easily detected on baropodograms as the increased plantar pressure on the anterior-medial part of the sole, and lateral displacements of the anterior maximal pressure point and the foot thrust center. These mechanical signs, consistent with foot inversion, induce external rotation of the leg and pelvic rotation on the stimulated side, leading to contralateral plantar-pressure changes: decreased maximal pressure point and thrust in the posterior part of the footprint and lateral displacement of the foot thrust center. Electrical stimulation of the abductor hallucis muscle in the loaded foot induces immediate specific changes in baropodogram indices, some of which persist 2 months later. The mechanical effect of abductor hallucis muscle stimulation (foot inversion) and its post-contraction state could be useful in podiatric and postural rehabilitation.

  11. Human brain activity associated with painful mechanical stimulation to muscle and bone.

    Science.gov (United States)

    Maeda, Lynn; Ono, Mayu; Koyama, Tetsuo; Oshiro, Yoshitetsu; Sumitani, Masahiko; Mashimo, Takashi; Shibata, Masahiko

    2011-08-01

    The purpose of this study was to elucidate the central processing of painful mechanical stimulation to muscle and bone by measuring blood oxygen level-dependent signal changes using functional magnetic resonance imaging (fMRI). Twelve healthy volunteers were enrolled. Mechanical pressure on muscle and bone were applied at the right lower leg by an algometer. Intensities were adjusted to cause weak and strong pain sensation at either target site in preliminary testing. Brain activation in response to mechanical nociceptive stimulation targeting muscle and bone were measured by fMRI and analyzed. Painful mechanical stimulation targeting muscle and bone activated the common areas including bilateral insula, anterior cingulate cortex, posterior cingulate cortex, secondary somatosensory cortex (S2), inferior parietal lobe, and basal ganglia. The contralateral S2 was more activated by strong stimulation than by weak stimulation. Some areas in the basal ganglia (bilateral putamen and caudate nucleus) were more activated by muscle stimulation than by bone stimulation. The putamen and caudate nucleus may have a more significant role in brain processing of muscle pain compared with bone pain.

  12. Testosterone Combined with Electrical Stimulation and Standing: Effect on Muscle and Bone

    Science.gov (United States)

    2017-10-01

    AWARD NUMBER: W81XWH-14-2-0190 TITLE: Testosterone Combined with Electrical Stimulation and Standing: Effect on Muscle and Bone PRINCIPAL...including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing...29 Sep 2017 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Testosterone Combined with Electrical Stimulation and Standing: Effect on Muscle and Bone 5b

  13. Bioelectrical activity of limb muscles during cold shivering of stimulation of the vestibular apparatus

    Science.gov (United States)

    Kuzmina, G. I.

    1980-01-01

    The effects of caloric and electric stimulation of the vestibular receptors on the EMG activity of limb muslces in anesthetized cats during cold induced shivering involved flexor muscles alone. Both types of stimulation suppressed bioelectrical activity more effectively in the ipsilateral muscles. The suppression of shivering activity seems to be due to the increased inhibitory effect of descending labyrinth pathways on the function of flexor motoneurons.

  14. Functional electrical stimulation of intrinsic laryngeal muscles under varying loads in exercising horses.

    Directory of Open Access Journals (Sweden)

    Jon Cheetham

    Full Text Available Bilateral vocal fold paralysis (BVCP is a life threatening condition and appears to be a good candidate for therapy using functional electrical stimulation (FES. Developing a working FES system has been technically difficult due to the inaccessible location and small size of the sole arytenoid abductor, the posterior cricoarytenoid (PCA muscle. A naturally-occurring disease in horses shares many functional and etiological features with BVCP. In this study, the feasibility of FES for equine vocal fold paralysis was explored by testing arytenoid abduction evoked by electrical stimulation of the PCA muscle. Rheobase and chronaxie were determined for innervated PCA muscle. We then tested the hypothesis that direct muscle stimulation can maintain airway patency during strenuous exercise in horses with induced transient conduction block of the laryngeal motor nerve. Six adult horses were instrumented with a single bipolar intra-muscular electrode in the left PCA muscle. Rheobase and chronaxie were within the normal range for innervated muscle at 0.55±0.38 v and 0.38±0.19 ms respectively. Intramuscular stimulation of the PCA muscle significantly improved arytenoid abduction at all levels of exercise intensity and there was no significant difference between the level of abduction achieved with stimulation and control values under moderate loads. The equine larynx may provide a useful model for the study of bilateral fold paralysis.

  15. FUSIMOTOR EFFECTS OF MIDBRAIN STIMULATION ON JAW MUSCLE-SPINDLES OF THE ANESTHETIZED CAT

    NARCIS (Netherlands)

    TAYLOR, A; JUCH, PJW

    The effects of electrical stimulation within the midbrain on fusimotor output to the jaw elevator muscles were studied in anaesthetized cats. Muscle spindle afferents recorded in the mesencephalic trigeminal nucleus were categorised as primary or secondary by their responses to succinylcholine

  16. Stretch-stimulated glucose transport in skeletal muscle is regulated by Rac1

    DEFF Research Database (Denmark)

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

    2015-01-01

    -stimulated glucose transport and signaling is unknown. We therefore investigated whether stretch-induced glucose transport in skeletal muscle required Rac1 and the actin cytoskeleton. We used muscle specific inducible Rac1 knockout mice as well as pharmacological inhibitors of Rac1 and the actin cytoskeleton...

  17. Contributions to muscle force and EMG by combined neural excitation and electrical stimulation

    Science.gov (United States)

    Crago, Patrick E.; Makowski, Nathaniel S.; Cole, Natalie M.

    2014-10-01

    Objective. Stimulation of muscle for research or clinical interventions is often superimposed on ongoing physiological activity without a quantitative understanding of the impact of the stimulation on the net muscle activity and the physiological response. Experimental studies show that total force during stimulation is less than the sum of the isolated voluntary and stimulated forces, but the occlusion mechanism is not understood. Approach. We develop a model of efferent motor activity elicited by superimposing stimulation during a physiologically activated contraction. The model combines action potential interactions due to collision block, source resetting, and refractory periods with previously published models of physiological motor unit recruitment, rate modulation, force production, and EMG generation in human first dorsal interosseous muscle to investigate the mechanisms and effectiveness of stimulation on the net muscle force and EMG. Main results. Stimulation during a physiological contraction demonstrates partial occlusion of force and the neural component of the EMG, due to action potential interactions in motor units activated by both sources. Depending on neural and stimulation firing rates as well as on force-frequency properties, individual motor unit forces can be greater, smaller, or unchanged by the stimulation. In contrast, voluntary motor unit EMG potentials in simultaneously stimulated motor units show progressive occlusion with increasing stimulus rate. The simulations predict that occlusion would be decreased by a reverse stimulation recruitment order. Significance. The results are consistent with and provide a mechanistic interpretation of previously published experimental evidence of force occlusion. The models also predict two effects that have not been reported previously—voluntary EMG occlusion and the advantages of a proximal stimulation site. This study provides a basis for the rational design of both future experiments and clinical

  18. Artificial control of muscle by endoneural multi electrode stimulation and sensing

    NARCIS (Netherlands)

    Rutten, Wim; Bouwman, R.L.M.

    1991-01-01

    Artificial electrical stimulation of motor nerves for muscle control can be made selective by using intrafascicular micro electrode arrays which contact many individual or small groups of nerve fibres. If at the same time te electrode arrays could record afferent information from the stimulated

  19. Sensory nerve cross-anastomosis and electrical muscle stimulation synergistically enhance functional recovery of chronically denervated muscle.

    Science.gov (United States)

    Willand, Michael P; Holmes, Michael; Bain, James R; de Bruin, Hubert; Fahnestock, Margaret

    2014-11-01

    Long-term muscle denervation leads to severe and irreversible atrophy coupled with loss of force and motor function. These factors contribute to poor functional recovery following delayed reinnervation. The authors' previous work demonstrated that temporarily suturing a sensory nerve to the distal motor stump (called sensory protection) significantly reduces muscle atrophy and improves function following reinnervation. The authors have also shown that 1 month of electrical stimulation of denervated muscle significantly improves function and reduces atrophy. In this study, the authors tested whether a combination of sensory protection and electrical stimulation would enhance functional recovery more than either treatment alone. Rat gastrocnemius muscles were denervated by cutting the tibial nerve. The peroneal nerve was then sutured to the distal tibial stump following 3 months of treatment (i.e., electrical stimulation, sensory protection, or both). Three months after peroneal repair, functional and histologic measurements were taken. All treatment groups had significantly higher muscle weight (pstimulation or sensory protection alone. The combined treatment also produced motor unit counts significantly greater than sensory protection alone (p<0.05). The combination treatment synergistically reduces atrophy and improves reinnervation and functional measures following delayed nerve repair, suggesting that these approaches work through different mechanisms. The authors' research supports the clinical use of both modalities together following peripheral nerve injury.

  20. 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.

  1. Leucine supplementation stimulates protein synthesis and reduces degradation signal activation in muscle of newborn pigs during acute endotoxemia

    Science.gov (United States)

    Sepsis disrupts skeletal muscle proteostasis and mitigates the anabolic response to leucine (Leu) in muscle of mature animals. We have shown that Leu stimulates muscle protein synthesis (PS) in healthy neonatal piglets. To determine if supplemental Leu can stimulate PS and reduce protein degradation...

  2. Regulation of autophagy in human skeletal muscle: effects of exercise, exercise training and insulin stimulation

    DEFF Research Database (Denmark)

    Fritzen, Andreas Mæchel; Madsen, Agnete Louise Bjerregaard; Kleinert, Maximilian

    2016-01-01

    Studies in rodent muscle suggest that autophagy is regulated by acute exercise, exercise training and insulin stimulation. However, little is known about the regulation of autophagy in human skeletal muscle. Here we investigate the autophagic response to acute one-legged exercise, one-legged exer......Studies in rodent muscle suggest that autophagy is regulated by acute exercise, exercise training and insulin stimulation. However, little is known about the regulation of autophagy in human skeletal muscle. Here we investigate the autophagic response to acute one-legged exercise, one......-legged exercise training as well as in response to subsequent insulin stimulation in exercised and non-exercised human muscle. Acute one-legged exercise decreased (phuman muscle....... The decrease in LC3-II/LC3-I ratio did not correlate with activation of AMPK trimer complexes in human muscle. Consistently, pharmacological AMPK activation with AICAR in mouse muscle did not affect the LC3-II/LC3-I ratio. Four hours after exercise, insulin further reduced (p

  3. 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

  4. Evaluation of the neuromuscular compartments in the peroneus longus muscle through electrical stimulation and accelerometry

    Directory of Open Access Journals (Sweden)

    Guillermo A. Mendez

    2013-10-01

    Full Text Available BACKGROUND: Muscles are innervated exclusively by a nerve branch and possess definite actions. However, mammalian skeletal muscles, such as the trapezius, the medial gastrocnemius, and the peroneus longus, are compartmentalized. In the peroneus longus muscle, multiple motor points, which innervate individual neuromuscular compartments (NMC, the superior (S-NMC, anteroinferior (AI-NMC, and posteroinferior (PI-NMC, have been described. The contribution of each neuromuscular compartment to the final action of the muscle is fundamental for the rehabilitation of patients afflicted by neurological and muscle dysfunctions. Interventions are often based on electrical principles that take advantage of the physiological characteristics of muscles and nerves to generate therapeutic effects. OBJECTIVE: To compare the effects of stimulating the different neuromuscular compartments (NMCs of the peroneus longus muscle on the motor threshold (MT and acceleration of the foot. METHOD: This is a cross-sectional study comprising 37 subjects. The three NMCs of the peroneus longus muscle were stimulated, and the acceleration of the foot and the motor threshold of each NMC were evaluated. A repeated measures analysis of variance with Bonferroni corrections of two intra-subjects factors was performed. RESULTS: The stimulation of the different NMCs did not result in any differences in MT (F=2.635, P=0.079. There were significant differences between the axes of acceleration caused by the stimulation of the different NMCs (F=56,233; P=0.000. The stimulation of the posteroinferior compartment resulted in the greatest acceleration in the X-axis (mean 0.614; standard deviation 0.253. CONCLUSIONS: The posteroinferior compartment primarily contributes to the eversion movement of the foot. NMCs have specific functional roles that contribute to the actions of the muscles to which they belong.

  5. Neuromuscular electrical stimulation as a method to maximize the beneficial effects of muscle stem cells transplanted into dystrophic skeletal muscle.

    Directory of Open Access Journals (Sweden)

    Giovanna Distefano

    Full Text Available Cellular therapy is a potential approach to improve the regenerative capacity of damaged or diseased skeletal muscle. However, its clinical use has often been limited by impaired donor cell survival, proliferation and differentiation following transplantation. Additionally, functional improvements after transplantation are all-too-often negligible. Because the host microenvironment plays an important role in the fate of transplanted cells, methods to modulate the microenvironment and guide donor cell behavior are warranted. The purpose of this study was to investigate whether the use of neuromuscular electrical stimulation (NMES for 1 or 4 weeks following muscle-derived stem cell (MDSC transplantation into dystrophic skeletal muscle can modulate the fate of donor cells and enhance their contribution to muscle regeneration and functional improvements. Animals submitted to 4 weeks of NMES after transplantation demonstrated a 2-fold increase in the number of dystrophin+ myofibers as compared to control transplanted muscles. These findings were concomitant with an increased vascularity in the MDSC+NMES group when compared to non-stimulated counterparts. Additionally, animals subjected to NMES (with or without MDSC transplantation presented an increased maximal specific tetanic force when compared to controls. Although cell transplantation and/or the use of NMES resulted in no changes in fatigue resistance, the combination of both MDSC transplantation and NMES resulted in a faster recovery from fatigue, when compared to non-injected and non-stimulated counterparts. We conclude that NMES is a viable method to improve MDSC engraftment, enhance dystrophic muscle strength, and, in combination with MDSC transplantation, improve recovery from fatigue. These findings suggest that NMES may be a clinically-relevant adjunct approach for cell transplantation into skeletal muscle.

  6. Evoked EMG-based torque prediction under muscle fatigue in implanted neural stimulation

    Science.gov (United States)

    Hayashibe, Mitsuhiro; Zhang, Qin; Guiraud, David; Fattal, Charles

    2011-10-01

    In patients with complete spinal cord injury, fatigue occurs rapidly and there is no proprioceptive feedback regarding the current muscle condition. Therefore, it is essential to monitor the muscle state and assess the expected muscle response to improve the current FES system toward adaptive force/torque control in the presence of muscle fatigue. Our team implanted neural and epimysial electrodes in a complete paraplegic patient in 1999. We carried out a case study, in the specific case of implanted stimulation, in order to verify the corresponding torque prediction based on stimulus evoked EMG (eEMG) when muscle fatigue is occurring during electrical stimulation. Indeed, in implanted stimulation, the relationship between stimulation parameters and output torques is more stable than external stimulation in which the electrode location strongly affects the quality of the recruitment. Thus, the assumption that changes in the stimulation-torque relationship would be mainly due to muscle fatigue can be made reasonably. The eEMG was proved to be correlated to the generated torque during the continuous stimulation while the frequency of eEMG also decreased during fatigue. The median frequency showed a similar variation trend to the mean absolute value of eEMG. Torque prediction during fatigue-inducing tests was performed based on eEMG in model cross-validation where the model was identified using recruitment test data. The torque prediction, apart from the potentiation period, showed acceptable tracking performances that would enable us to perform adaptive closed-loop control through implanted neural stimulation in the future.

  7. Selective and graded recruitment of cat hamstring muscles with intrafascicular stimulation.

    Science.gov (United States)

    Dowden, Brett R; Wilder, Andrew M; Hiatt, Scott D; Normann, Richard A; Brown, Nicholas A T; Clark, Gregory A

    2009-12-01

    The muscles of the hamstring group can produce different combinations of hip and knee torque. Thus, the ability to activate the different hamstring muscles selectively is of particular importance in eliciting functional movements such as stance and gait in a person with spinal cord injury. We investigated the ability of intrafascicular stimulation of the muscular branch of the sciatic nerve to recruit the feline hamstring muscles in a selective and graded fashion. A Utah Slanted Electrode Array, consisting of 100 penetrating microelectrodes, was implanted into the muscular branch of the sciatic nerve in six cats. Muscle twitches were evoked in the three compartments of biceps femoris (anterior, middle, and posterior), as well as semitendinosus and semimembranosus, using pulse-width modulated constant-voltage pulses. The resultant compound muscle action potentials were recorded using intramuscular fine-wire electrodes. 74% of the electrodes per implant were able to evoke a threshold response in these muscles, and these electrodes were evenly distributed among the instrumented muscles. Of the five muscles instrumented, on average 2.5 could be selectively activated to 90% of maximum EMG, and 3.5 could be selectively activated to 50% of maximum EMG. The muscles were recruited selectively with a mean stimulus dynamic range of 4.14 +/- 5.05 dB between threshold and either spillover to another muscle or a plateau in the response. This selective and graded activation afforded by intrafascicular stimulation of the muscular branch of the sciatic nerve suggests that it is a potentially useful stimulation paradigm for eliciting distinct forces in the hamstring muscle group in motor neuroprosthetic applications.

  8. Regulation of autophagy in human skeletal muscle: effects of exercise, exercise training and insulin stimulation

    Science.gov (United States)

    Fritzen, Andreas M.; Madsen, Agnete B.; Kleinert, Maximilian; Treebak, Jonas T.; Lundsgaard, Anne‐Marie; Jensen, Thomas E.; Richter, Erik A.; Wojtaszewski, Jørgen; Kiens, Bente

    2016-01-01

    Key points Regulation of autophagy in human muscle in many aspects differs from the majority of previous reports based on studies in cell systems and rodent muscle.An acute bout of exercise and insulin stimulation reduce human muscle autophagosome content.An acute bout of exercise regulates autophagy by a local contraction‐induced mechanism.Exercise training increases the capacity for formation of autophagosomes in human muscle.AMPK activation during exercise seems insufficient to regulate autophagosome content in muscle, while mTORC1 signalling via ULK1 probably mediates the autophagy‐inhibiting effect of insulin. Abstract Studies in rodent muscle suggest that autophagy is regulated by acute exercise, exercise training and insulin stimulation. However, little is known about the regulation of autophagy in human skeletal muscle. Here we investigate the autophagic response to acute one‐legged exercise, one‐legged exercise training and subsequent insulin stimulation in exercised and non‐exercised human muscle. Acute one‐legged exercise decreased (Pexercise in human muscle. The decrease in LC3‐II/LC3‐I ratio did not correlate with activation of 5′AMP activated protein kinase (AMPK) trimer complexes in human muscle. Consistently, pharmacological AMPK activation with 5‐aminoimidazole‐4‐carboxamide riboside (AICAR) in mouse muscle did not affect the LC3‐II/LC3‐I ratio. Four hours after exercise, insulin further reduced (Pexercised and non‐exercised leg in humans. This coincided with increased Ser‐757 phosphorylation of Unc51 like kinase 1 (ULK1), which is suggested as a mammalian target of rapamycin complex 1 (mTORC1) target. Accordingly, inhibition of mTOR signalling in mouse muscle prevented the ability of insulin to reduce the LC3‐II/LC3‐I ratio. In response to 3 weeks of one‐legged exercise training, the LC3‐II/LC3‐I ratio decreased (Pexercise and insulin stimulation reduce muscle autophagosome content, while exercise

  9. Electrical stimulation as a biomimicry tool for regulating muscle cell behavior.

    Science.gov (United States)

    Ahadian, Samad; Ostrovidov, Serge; Hosseini, Vahid; Kaji, Hirokazu; Ramalingam, Murugan; Bae, Hojae; Khademhosseini, Ali

    2013-01-01

    There is a growing need to understand muscle cell behaviors and to engineer muscle tissues to replace defective tissues in the body. Despite a long history of the clinical use of electric fields for muscle tissues in vivo, electrical stimulation (ES) has recently gained significant attention as a powerful tool for regulating muscle cell behaviors in vitro. ES aims to mimic the electrical environment of electroactive muscle cells (e.g., cardiac or skeletal muscle cells) by helping to regulate cell-cell and cell-extracellular matrix (ECM) interactions. As a result, it can be used to enhance the alignment and differentiation of skeletal or cardiac muscle cells and to aid in engineering of functional muscle tissues. Additionally, ES can be used to control and monitor force generation and electrophysiological activity of muscle tissues for bio-actuation and drug-screening applications in a simple, high-throughput, and reproducible manner. In this review paper, we briefly describe the importance of ES in regulating muscle cell behaviors in vitro, as well as the major challenges and prospective potential associated with ES in the context of muscle tissue engineering.

  10. 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

  11. Molecular and cellular mechanisms of muscle aging and sarcopenia and effects of electrical stimulation in seniors

    Directory of Open Access Journals (Sweden)

    Laura Barberi

    2015-08-01

    Full Text Available The prolongation of skeletal muscle strength in aging and neuromuscular disease has been the objective of numerous studies employing a variety of approaches. It is generally accepted that cumulative failure to repair damage related to an overall decrease in anabolic processes is a primary cause of functional impairment in muscle. The functional performance of skeletal muscle tissues declines during post- natal life and it is compromised in different diseases, due to an alteration in muscle fiber composition and an overall decrease in muscle integrity as fibrotic invasions replace functional contractile tissue. Characteristics of skeletal muscle aging and diseases include a conspicuous reduction in myofiber plasticity (due to the progressive loss of muscle mass and in particular of the most powerful fast fibers, alteration in muscle-specific transcriptional mechanisms, and muscle atrophy. An early decrease in protein synthetic rates is followed by a later increase in protein degradation, to affect biochemical, physiological, and morphological parameters of muscle fibers during the aging process. Alterations in regenerative pathways also compromise the functionality of muscle tissues. In this review we will give an overview of the work on molecular and cellular mechanisms of aging and sarcopenia and the effects of electrical stimulation in seniors.

  12. Electrical Stimulation of Denervated Rat Skeletal Muscle Retards Capillary and Muscle Loss in Early Stages of Disuse Atrophy

    Directory of Open Access Journals (Sweden)

    Kouki Nakagawa

    2017-01-01

    Full Text Available The purpose of the present study is to investigate the effects of low-frequency electrical muscle stimulation (ES on the decrease in muscle mass, fiber size, capillary supply, and matrix metalloproteinase (MMP immunoreactivity in the early stages of denervation-induced limb disuse. Direct ES was performed on the tibialis anterior muscle following denervation in seven-week-old male rats. The rats were divided into the following groups: control (CON, denervation (DN, and denervation with direct ES (DN + ES. Direct ES was performed at an intensity of 16 mA and a frequency of 10 Hz for 30 min per day, six days a week, for one week. We performed immunohistochemical staining to determine the expression of dystrophin, CD34, and MMP-2 in transverse sections of TA muscles. The weight, myofiber cross-sectional area (FCSA, and capillary-to-fiber (C/F ratio of the tibialis anterior (TA muscle were significantly reduced in the DN group compared to the control and DN + ES groups. The MMP-2 positive area was significantly greater in DN and DN + ES groups compared to the control group. These findings suggest beneficial effects of direct ES in reducing muscle atrophy and capillary regression without increasing MMP-2 immunoreactivity in the early stages of DN-induced muscle disuse in rat hind limbs.

  13. Electrical Stimulation of Denervated Rat Skeletal Muscle Retards Capillary and Muscle Loss in Early Stages of Disuse Atrophy

    Science.gov (United States)

    Nakagawa, Kouki; Hayao, Keishi; Yotani, Kengo; Ogita, Futoshi; Yamamoto, Noriaki; Onishi, Hideaki

    2017-01-01

    The purpose of the present study is to investigate the effects of low-frequency electrical muscle stimulation (ES) on the decrease in muscle mass, fiber size, capillary supply, and matrix metalloproteinase (MMP) immunoreactivity in the early stages of denervation-induced limb disuse. Direct ES was performed on the tibialis anterior muscle following denervation in seven-week-old male rats. The rats were divided into the following groups: control (CON), denervation (DN), and denervation with direct ES (DN + ES). Direct ES was performed at an intensity of 16 mA and a frequency of 10 Hz for 30 min per day, six days a week, for one week. We performed immunohistochemical staining to determine the expression of dystrophin, CD34, and MMP-2 in transverse sections of TA muscles. The weight, myofiber cross-sectional area (FCSA), and capillary-to-fiber (C/F) ratio of the tibialis anterior (TA) muscle were significantly reduced in the DN group compared to the control and DN + ES groups. The MMP-2 positive area was significantly greater in DN and DN + ES groups compared to the control group. These findings suggest beneficial effects of direct ES in reducing muscle atrophy and capillary regression without increasing MMP-2 immunoreactivity in the early stages of DN-induced muscle disuse in rat hind limbs. PMID:28497057

  14. Combined effect of electrical stimulation and blade tenderization on some bovine muscles

    Energy Technology Data Exchange (ETDEWEB)

    Raccach, M.; Henrickson, R.L.

    1979-01-01

    The electrical stimulation (ES) period was a very important factor determining the tenderness of three bovine muscles: Biceps femoris (BF), Longissimus dorsi (LD), and Semimembranosus (SM). Tenderness (shear force values) increased in most cases with increasing the ES period. An ES period of 15 min was optimal for obtaining a tenderness equal to that obtained by conventional processing of beef. The shortest ES period used (1 min) was adequate in most cases to set the muscles in rigor mortis and in preventing cold shortening. The tenderness of blade tenderized muscles was in most cases independent from the ES period. Blade tenderization was very effective to tenderize the BF muscle followed in decreasing order of efficacy by the LD and SM muscles. The cooking times and cooking losses of the three muscles were not affected by either the ES period or by blade tenderization.

  15. 99mTc-sestamibi muscle scintigraphy to assess the response to neuromuscular electrical stimulation of normal quadriceps femoris muscle

    International Nuclear Information System (INIS)

    Pekindil, Y.; Sarikaya, A.; Birtane, M.; Pekindil, G.; Salan, A.

    2001-01-01

    Neuromuscular electrical stimulation (NMES) is widely used for improving muscle strength by simultaneous contraction in the prevention of muscle atrophy. Although there exist many clinical methods for evaluating the therapeutic response of muscles, 99m Tc-sestamibi which is a skeletal muscle perfusion and metabolism agent has not previously been used for this purpose. The aim of our work was to ascertain whether 99m Tc-sestamibi muscle scintigraphy is useful in the monitoring of therapeutic response to NMES in healthy women. The study included 16 women aged between 21 and 45, with a mean age of 32.7±6.4. Both quadriceps femoris muscles (QFM) of each patient were studied. After randomization to remove the effect of the dominant side, one QFM of each patient was subjected to the NMES procedure for a period of 20 days. NMES was performed with an alternating biphasic rectangular current, from a computed electrical stimulator daily for 23 minutes. After measurement of skinfold thickness over the thigh, pre- and post-NMES girth measurements were assessed in centimeters. Sixty minutes after injections of 555 MBq 99m Tc-sestamibi, static images of the thigh were obtained for 5 minutes. The thigh-to-knee uptake ratio was calculated by semiquantitative analysis and normalized to body surface area (NUR=normalized uptake ratio). The difference between the pre and post NMES NUR values was significant (1.76±0.31 versus 2.25±0.38, p=0.0000). The percentage (%) increase in NUR values also well correlated with the % increase in thigh girth measurements (r=0.89, p=0.0000). These results indicated that 99m Tc-sestamibi muscle scintigraphy as a new tool may be useful in evaluating therapeutic response to NMES. (author)

  16. Epinephrine-stimulated glycogen breakdown activates glycogen synthase and increases insulin-stimulated glucose uptake in epitrochlearis muscles

    DEFF Research Database (Denmark)

    Kolnes, Anders J; Birk, Jesper Bratz; Eilertsen, Einar

    2015-01-01

    Adrenaline increases glycogen synthase (GS) phosphorylation and decreases GS activity but also stimulates glycogen breakdown and low glycogen content normally activates GS. To test the hypothesis that glycogen content directly regulates GS phosphorylation, glycogen breakdown was stimulated...... in condition with decreased GS activation. Saline or adrenaline (0.02mg/100g rat) was injected subcutaneously in Wistar rats (~130 g) with low (24 h fasted), normal (normal diet) and high glycogen content (fasted-refed) and epitrochlearis muscles were removed after 3 h and incubated ex vivo eliminating...... adrenaline action. Adrenaline injection reduced glycogen content in epitrochlearis muscles with high (120.7±17.8 vs 204.6±14.5 mmol•kg(-1); pglycogen (89.5±7.6 vs 152.6±8.1 mmol•kg(-1); pglycogen (90.0±5.0 vs 102.8±7.8 mmol•kg(-1); p=0...

  17. Acylated and unacylated ghrelin do not directly stimulate glucose transport in isolated rodent skeletal muscle.

    Science.gov (United States)

    Cervone, Daniel T; Dyck, David J

    2017-07-01

    Emerging evidence implicates ghrelin, a gut-derived, orexigenic hormone, as a potential mediator of insulin-responsive peripheral tissue metabolism. However, in vitro and in vivo studies assessing ghrelin's direct influence on metabolism have been controversial, particularly due to confounding factors such as the secondary rise in growth hormone (GH) after ghrelin injection. Skeletal muscle is important in the insulin-stimulated clearance of glucose, and ghrelin's exponential rise prior to a meal could potentially facilitate this. This study was aimed at elucidating any direct stimulatory action that ghrelin may have on glucose transport and insulin signaling in isolated rat skeletal muscle, in the absence of confounding secondary factors. Oxidative soleus and glycolytic extensor digitorum longus skeletal muscles were isolated from male Sprague Dawley rats in the fed state and incubated with various concentrations of acylated and unacylated ghrelin in the presence or absence of insulin. Ghrelin did not stimulate glucose transport in either muscle type, with or without insulin. Moreover, GH had no acute, direct stimulatory effect on either basal or insulin-stimulated muscle glucose transport. In agreement with the lack of observed effect on glucose transport, ghrelin and GH also had no stimulatory effect on Ser 473 AKT or Thr 172 AMPK phosphorylation, two key signaling proteins involved in glucose transport. Furthermore, to our knowledge, we are among the first to show that ghrelin can act independent of its receptor and cause an increase in calmodulin-dependent protein kinase 2 (CaMKII) phosphorylation in glycolytic muscle, although this was not associated with an increase in glucose transport. We conclude that both acylated and unacylated ghrelin have no direct, acute influence on skeletal muscle glucose transport. Furthermore, the immediate rise in GH in response to ghrelin also does not appear to directly stimulate glucose transport in muscle. © 2017 The

  18. Human brain activity associated with painful mechanical stimulation to muscle and bone

    OpenAIRE

    Maeda, Lynn; Ono, Mayu; Koyama, Tetsuo; Oshiro, Yoshitetsu; Sumitani, Masahiko; Mashimo, Takashi; Shibata, Masahiko

    2011-01-01

    Purpose The purpose of this study was to elucidate the central processing of painful mechanical stimulation to muscle and bone by measuring blood oxygen level-dependent signal changes using functional magnetic resonance imaging (fMRI). Methods Twelve healthy volunteers were enrolled. Mechanical pressure on muscle and bone were applied at the right lower leg by an algometer. Intensities were adjusted to cause weak and strong pain sensation at either target site in preliminary testing. Brain ac...

  19. IL-6 selectively stimulates fat metabolism in human skeletal muscle

    DEFF Research Database (Denmark)

    Wolsk, Emil; Mygind, Helene; Grøndahl, Thomas S

    2010-01-01

    and glucose metabolism and signaling of both adipose tissue and skeletal muscle. Eight healthy postabsorptive males were infused with either rhIL-6 or saline for 4 h, eliciting IL-6 levels of ~40 and ~1 pg/ml, respectively. Systemic, skeletal muscle, and adipose tissue fat and glucose metabolism was assessed......Interleukin (IL)-6 is chronically elevated in type 2 diabetes but also during exercise. However, the exact metabolic role, and hence the physiological significance, has not been elucidated. The objective of this study was to investigate the in vivo effect of recombinant human (rh) IL-6 on human fat...... before, during, and 2 h after cessation of the infusion. Glucose metabolism was unaffected by rhIL-6. In contrast, rhIL-6 increased systemic fatty acid oxidation approximately twofold after 60 min, and it remained elevated even 2 h after the infusion. The increase in oxidation was followed by an increase...

  20. IL-6 selectively stimulates fat metabolism in human skeletal muscle

    DEFF Research Database (Denmark)

    Wolsk, Emil; Mygind, Helene; Grøndahl, Thomas S

    2010-01-01

    and glucose metabolism and signaling of both adipose tissue and skeletal muscle. Eight healthy postabsorptive males were infused with either rhIL-6 or saline for 4 h, eliciting IL-6 levels of ∼40 and ∼1 pg/ml, respectively. Systemic, skeletal muscle, and adipose tissue fat and glucose metabolism was assessed......Interleukin (IL)-6 is chronically elevated in type 2 diabetes but also during exercise. However, the exact metabolic role, and hence the physiological significance, has not been elucidated. The objective of this study was to investigate the in vivo effect of recombinant human (rh) IL-6 on human fat...... before, during, and 2 h after cessation of the infusion. Glucose metabolism was unaffected by rhIL-6. In contrast, rhIL-6 increased systemic fatty acid oxidation approximately twofold after 60 min, and it remained elevated even 2 h after the infusion. The increase in oxidation was followed by an increase...

  1. Dynamics of force and muscle stimulation in human vertical jumping

    NARCIS (Netherlands)

    Bobbert, M.F.; van Zandwijk, J.P.

    1999-01-01

    PURPOSE: The purpose of this study was to gain insight into the importance of stimulation dynamics for force development in human vertical jumping. METHODS: Maximum height squat jumps were performed by 21 male subjects. As a measure of signal dynamics, rise time (RT) was used, i.e., the time taken

  2. Bilateral responses of upper limb muscles to transcranial magnetic stimulation in human subjects.

    Science.gov (United States)

    Bawa, P; Hamm, J D; Dhillon, P; Gross, P A

    2004-10-01

    Anatomical and behavioural work on primates has shown bilateral innervation of axial and proximal limb muscles, and contralateral control of distal limb muscles. The following study examined if a clear boundary exists between the distal and proximal upper limb muscles that are controlled contralaterally or bilaterally. The right motor cortical area representing the upper limb was stimulated, while surface EMG was recorded bilaterally from various upper limb muscles during rest and phasic voluntary contractions. Peak-to-peak amplitude of motor evoked potential (MEP) was measured for each muscle on both sides. The ratio R = (ipsilateral MEP: contralateral MEP) was calculated for seven pairs of muscles. For each of the seven pairs, R was less than 1.0, implying that for each muscle and subject, the contralateral control is stronger. The boundary where R changed from almost zero to a clearly measurable magnitude depended on the subject. Ipsilateral MEPs from trapezius and pectoralis could be recorded with a small background contraction from almost all subjects; on the other hand, in deltoid and biceps brachii, ipsilateral MEPs were observed only with bimanual phasic contractions. The forearm and hand muscles, in general, did not show any ipsilateral MEPs. Major differences between subjects lay in the presence or the absence of ipsilateral MEPs in biceps brachii and deltoid, without defining a sharp boundary between proximal and distal muscles.

  3. Hyperexcitability to electrical stimulation and accelerated muscle fatiguability of taut bands in rats.

    Science.gov (United States)

    Wang, Yong-Hui; Yin, Ming-Jing; Fan, Zhen-Zhen; Arendt-Nielsen, Lars; Ge, Hong-You; Yue, Shou-Wei

    2014-04-01

    Myofascial trigger points contribute significantly to musculoskeletal pain and motor dysfunction and may be associated with accelerated muscle fatiguability. The aim of this study was to investigate the electrically induced force and fatigue characteristics of muscle taut bands in rats. Muscle taut bands were dissected out and subjected to trains of electrical stimulation. The electrical threshold intensity for muscle contraction and maximum contraction force (MCF), electrical intensity dependent fatigue and electrical frequency dependent fatigue characteristics were assessed in three different sessions (n=10 each) and compared with non-taut bands in the biceps femoris muscle. The threshold intensity for muscle contraction and MCF at the 10th, 15th and 20th intensity dependent fatigue stimuli of taut bands were significantly lower than those of non-taut bands (all pbands were significantly lower than those at the 1st and 5th stimuli (all pbands than for non-taut bands (both pband itself was more excitable to electrical stimulation and significantly less fatigue resistant than normal muscle fibres.

  4. 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.

  5. 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.

  6. Middle cerebral artery flow velocity and blood flow during exercise and muscle ischemia in humans

    DEFF Research Database (Denmark)

    Jørgensen, L G; Perko, M; Hanel, B

    1992-01-01

    Changes in middle cerebral artery flow velocity (Vmean), measured by transcranial Doppler ultrasound, were used to determine whether increases in mean arterial pressure (MAP) or brain activation enhance cerebral perfusion during exercise. We also evaluated the role of "central command......, they support the hypothesis that cerebral perfusion during exercise reflects an increase in brain activation that is independent of MAP, central command, and muscle metaboreceptors but is likely to depend on influence of mechanoreceptors.......," mechanoreceptors, and/or muscle "metaboreceptors" on cerebral perfusion. Ten healthy subjects performed two levels of dynamic exercise corresponding to a heart rate of 110 (range 89-134) and 148 (129-170) beats/min, respectively, and exhaustive one-legged static knee extension. Measurements were continued during 2...

  7. IGF1 stimulates greater muscle hypertrophy in the absence of myostatin in male mice

    Science.gov (United States)

    Insulin-like growth factors (IGFs) and myostatin have opposing roles in regulating the growth and size of skeletal muscle, with IGF1 stimulating, and myostatin inhibiting, growth. However, it remains unclear whether these proteins have mutually dependent, or independent, roles. To clarify this issue...

  8. Muscle potentials evoked by magnetic stimulation of the sciatic nerve in unilateral sciatic nerve dysfunction

    NARCIS (Netherlands)

    Van Soens, I.; Struys, M. M. R. F.; Van Ham, L. M. L.

    Magnetic stimulation of the sciatic nerve and subsequent recording of the muscle-evoked potential (MEP) was performed in eight dogs and three cats with unilateral sciatic nerve dysfunction. Localisation of the lesion in the sciatic nerve was based on the history, clinical neurological examination

  9. 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.

  10. Mechanical stimulation in the engineering of heart muscle.

    Science.gov (United States)

    Liaw, Norman Yu; Zimmermann, Wolfram-Hubertus

    2016-01-15

    Recreating the beating heart in the laboratory continues to be a formidable bioengineering challenge. The fundamental feature of the heart is its pumping action, requiring considerable mechanical forces to compress a blood filled chamber with a defined in- and outlet. Ventricular output crucially depends on venous loading of the ventricles (preload) and on the force generated by the preloaded ventricles to overcome arterial blood pressure (afterload). The rate of contraction is controlled by the spontaneously active sinus node and transmission of its electrical impulses into the ventricles. The underlying principles for these physiological processes are described by the Frank-Starling mechanism and Bowditch phenomenon. It is essential to consider these principles in the design and evaluation of tissue engineered myocardium. This review focuses on current strategies to evoke mechanical loading in hydrogel-based heart muscle engineering. Copyright © 2015. Published by Elsevier B.V.

  11. Blood flow distribution in dog gastrocnemius muscle at rest and during stimulation

    International Nuclear Information System (INIS)

    Piiper, J.; Pendergast, D.R.; Marconi, C.; Meyer, M.; Heisler, N.; Cerretelli, P.

    1985-01-01

    The distribution of blood flow within the isolated perfused dog gastrocnemius muscle (weight 100-240 g) was studied by intra-arterial injection of radioactively labeled microspheres (diameter 15 micron) at rest and during supramaximal stimulation to rhythmic isotonic tetanic contractions of varied frequency against varied loads. After the experiment the muscle was cut into 180-250 pieces of approximately 0.75 g each, and the blood flow to each muscle piece was determined from its radioactivity. The inhomogeneity of blood flow was represented as the frequency distribution of the ratios of regional specific blood flow, i.e., blood flow per unit tissue weight of the piece, QR, to the overall specific blood flow of the muscle, Q. The QR/Q values for the individual pieces of a muscle were found to vary widely both at rest and during stimulation. With rising work load the frequency distribution had a tendency to broaden and flatten, indicating increasing perfusion inhomogeneity. On the average of the experiments, there was no significant difference in specific blood flow between the three anatomic components of the gastrocnemius (lateral and medial heads of gastrocnemius and flexor digitorum superficialis) nor between the superficial and deep portions within these anatomic components, only the distal third of the muscle was relatively less perfused compared with the proximal two-thirds. The considerable inhomogeneity of blood flow as revealed by microsphere embolization and by other methods is expected to exert important limiting effects on local O 2 supply, particularly during exercise

  12. Repeatability and reliability of muscle relaxation properties induced by motor cortical stimulation.

    Science.gov (United States)

    Molenaar, Joery P; Voermans, Nicol C; de Jong, Lysanne A; Stegeman, Dick F; Doorduin, Jonne; van Engelen, Baziel G

    2018-03-15

    Impaired muscle relaxation is a feature of many neuromuscular disorders. However, there are few tests available to quantify muscle relaxation. Transcranial magnetic stimulation (TMS) of the motor cortex can induce muscle relaxation by abruptly inhibiting corticospinal drive. The aim of our study is to investigate if repeatability and reliability of TMS-induced relaxation is greater than voluntary relaxation. Furthermore, effects of sex, cooling and fatigue on muscle relaxation properties were studied. Muscle relaxation of deep finger flexors was assessed in twenty-five healthy subjects (14 M and 11 F, aged 39.1{plus minus}12.7 and 45.3{plus minus}8.7 years old, respectively) using handgrip dynamometry. All outcome measures showed greater repeatability and reliability in TMS-induced relaxation compared to voluntary relaxation. The within-subject coefficient of variability of normalized peak relaxation rate was lower in TMS-induced relaxation than in voluntary relaxation (3.0 vs 19.7% in men, and 6.1 vs 14.3% in women). The repeatability coefficient was lower (1.3 vs 6.1 s -1 in men and 2.3 vs 3.1 s -1 in women), and the intraclass correlation coefficient was higher (0.95 vs 0.53 in men and 0.78 vs 0.69 in women), for TMS-induced relaxation compared to voluntary relaxation. TMS enabled to demonstrate slowing effects of sex, muscle cooling, and muscle fatigue on relaxation properties that voluntary relaxation could not. In conclusion, repeatability and reliability of TMS-induced muscle relaxation was greater compared to voluntary muscle relaxation. TMS-induced muscle relaxation has the potential to be used in clinical practice for diagnostic purposes and therapy effect monitoring in patients with impaired muscle relaxation.

  13. Muscle reflexes during gait elicited by electrical stimulation of the posterior cruciate ligament in humans

    DEFF Research Database (Denmark)

    Fischer-Rasmussen, T; Krogsgaard, M R; Jensen, D B

    2002-01-01

    over the vastus medialis, rectus femoris, vastus lateralis, biceps femoris caput longum, and semitendinosus muscles. The stimuli consisted of four pulses delivered at 200 Hz; the stimulus amplitude was two to three times the sensory threshold. The electrical stimulation of the PCL inhibited the ongoing......We investigated the influence of electrical stimulation of the posterior cruciate ligament (PCL) on the motoneuron pool of the thigh and calf muscle during gait. The study group comprised eight young men without any history of injury to the knee joints. Multistranded teflon-insulated stainless...... steel wires were inserted into the PCL guided by sonography and in four subjects also into the fat pad of the knee. The PCL was electrically stimulated during gait on a treadmill at heel strike and 100 ms after heel strike. Electromyographic signals were recorded with bipolar surface electrodes placed...

  14. ALTERATION OF MUSCLE FUNCTION AFTER ELECTRICAL STIMULATION BOUT OF KNEE EXTENSORS AND FLEXORS

    Directory of Open Access Journals (Sweden)

    Marc Vanderthommen

    2012-12-01

    Full Text Available The purpose was to study the effects on muscle function of an electrical stimulation bout applied unilaterally on thigh muscles in healthy male volunteers. One group (ES group, n = 10 received consecutively 100 isometric contractions of quadriceps and 100 isometric contractions of hamstrings (on-off ratio 6-6 s induced by neuromuscular electrical stimulations (NMES. Changes in muscle torque, muscle soreness (0-10 VAS, muscle stiffness and serum creatine kinase (CK activity were assessed before the NMES exercise (pre-ex as well as 24h (d+1, 48h (d+2 and 120h (d+5 after the bout. A second group (control group, n = 10 were submitted to the same test battery than the ES group and with the same time-frame. The between-group comparison indicated a significant increase in VAS scores and in serum levels of CK only in the ES group. In the ES group, changes were more pronounced in hamstrings than in quadriceps and peaked at d+2 (quadriceps VAS scores = 2.20 ± 1.55 a.u. (0 at pre-ex; hamstrings VAS scores = 3.15 ± 2.14 a.u. (0 at pre-ex; hip flexion angle = 62 ± 5° (75 ± 6° at pre-ex; CK activity = 3021 ± 2693 IU·l-1 (136 ± 50 IU·l-1 at pre-ex. The results of the present study suggested the occurrence of muscle damage that could have been induced by the peculiar muscle recruitment in NMES and the resulting overrated mechanical stress. The sensitivity to the damaging effects of NMES appeared higher in the hamstrings than in quadriceps muscles

  15. Electrical Stimulation Frequency and Skeletal Muscle Characteristics: Effects on Force and Fatigue

    Directory of Open Access Journals (Sweden)

    Maria Vromans

    2017-12-01

    Full Text Available This investigation aimed to determine the force and muscle surface electromyography (EMG responses to different frequencies of electrical stimulation (ES in two groups of muscles with different size and fiber composition (fast- and slow-twitch fiber proportions during a fatigue-inducing protocol. Progression towards fatigue was evaluated in the abductor pollicis brevis (APB and vastus lateralis (VL when activated by ES at three frequencies (10, 35, and 50Hz. Ten healthy adults (mean age: 23.2 ± 3.0 years were recruited; participants signed an IRB approved consent form prior to participation. Protocols were developed to 1 identify initial ES current intensity required to generate the 25% maximal voluntary contraction (MVC at each ES frequency and 2 evaluate changes in force and EMG activity during ES-induced contraction at each frequency while progressing towards fatigue. For both muscles, stimulation at 10Hz required higher current intensity of ES to generate the initial force. There was a significant decline in force in response to ES-induced fatigue for all frequencies and for both muscles (p<0.05. However, the EMG response was not consistent between muscles. During the progression towards fatigue, the APB displayed an initial drop in force followed by an increase in EMG activity and the VL displayed a decrease in EMG activity for all frequencies. Overall, it appeared that there were some significant interactions between muscle size and fiber composition during progression towards fatigue for different ES frequencies. It could be postulated that muscle characteristics (size and fiber composition should be considered when evaluating progression towards fatigue as EMG and force responses are not consistent between muscles.

  16. Implantable power generation system utilizing muscle contractions excited by electrical stimulation.

    Science.gov (United States)

    Sahara, Genta; Hijikata, Wataru; Tomioka, Kota; Shinshi, Tadahiko

    2016-06-01

    An implantable power generation system driven by muscle contractions for supplying power to active implantable medical devices, such as pacemakers and neurostimulators, is proposed. In this system, a muscle is intentionally contracted by an electrical stimulation in accordance with the demands of the active implantable medical device for electrical power. The proposed system, which comprises a small electromagnetic induction generator, electrodes with an electrical circuit for stimulation and a transmission device to convert the linear motion of the muscle contractions into rotational motion for the magneto rotor, generates electrical energy. In an ex vivo demonstration using the gastrocnemius muscle of a toad, which was 28 mm in length and weighed 1.3 g, the electrical energy generated by the prototype exceeded the energy consumed for electrical stimulation, with the net power being 111 µW. It was demonstrated that the proposed implantable power generation system has the potential to replace implantable batteries for active implantable medical devices. © IMechE 2016.

  17. Plasma Amino Acids Stimulate Uncoupled Respiration of Muscle Subsarcolemmal Mitochondria in Lean but Not Obese Humans.

    Science.gov (United States)

    Kras, Katon A; Hoffman, Nyssa; Roust, Lori R; Patel, Shivam H; Carroll, Chad C; Katsanos, Christos S

    2017-12-01

    Obesity is associated with mitochondrial dysfunction in skeletal muscle. Increasing the plasma amino acid (AA) concentrations stimulates mitochondrial adenosine triphosphate (ATP) production in lean individuals. To determine whether acute elevation in plasma AAs enhances muscle mitochondrial respiration and ATP production in subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondria in obese adults. Assessment of SS and IMF mitochondrial function during saline (i.e., control) and AA infusions. Eligible participants were healthy lean (body mass index, mass index >30 kg/m2; age 35 ± 3 years; n = 11) subjects. Single trial of saline infusion followed by AA infusion. SS and IMF mitochondria were isolated from muscle biopsies collected at the end of the saline and AA infusions. Mitochondrial respiration and ATP production. AA infusion increased adenosine 5'-diphosphate (ADP)-stimulated respiration and ATP production rates of SS mitochondria in the lean (P lean subjects only (P lean or obese subjects (P > 0.05). Increasing the plasma AA concentrations enhances the capacity for respiration and ATP production of muscle SS, but not IMF, mitochondria in lean individuals, in parallel with increases in uncoupled respiration. However, neither of these parameters increases in muscle SS or IMF mitochondria in obese individuals. Copyright © 2017 Endocrine Society

  18. ANODAL TRANSCRANIAL DIRECT CURRENT STIMULATION (TDCS) INCREASES ISOMETRIC STRENGTH OF SHOULDER ROTATORS MUSCLES IN HANDBALL PLAYERS.

    Science.gov (United States)

    Hazime, Fuad Ahmad; da Cunha, Ronaldo Alves; Soliaman, Renato Rozenblit; Romancini, Ana Clara Bezerra; Pochini, Alberto de Castro; Ejnisman, Benno; Baptista, Abrahão Fontes

    2017-06-01

    Weakness of the rotator cuff muscles can lead to imbalances in the strength of shoulder external and internal rotators, change the biomechanics of the glenohumeral joint and predispose an athlete to injury. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that has demonstrated promising results in a variety of health conditions. However few studies addressed its potential approach in the realm of athletics. The purpose of this study was to investigate if transcranial direct current stimulation (tDCS) technique increases the isometric muscle strength of shoulder external and internal rotators in handball athletes. Randomized, double-blind, placebo-controlled, crossover study. Eight female handball players aged between 17 and 21 years (Mean=19.65; SD=2.55) with 7.1 ± 4.8 years of experience in training, participating in regional and national competitions were recruited. Maximal voluntary isometric contraction (MVIC) of shoulder external and internal rotator muscles was evaluated during and after 30 and 60 minutes post one session of anodal and sham current (2mA; 0.057mA/cm 2 ) with a one-week interval between stimulations. Compared to baseline, MVIC of shoulder external and internal rotators significantly increased after real but not sham tDCS. Between-group differences were observed for external and internal rotator muscles. Maximal voluntary isometric contraction of external rotation increased significantly during tDCS, and 30 and 60 minutes post-tDCS for real tDCS compared to that for sham tDCS. For internal rotation MVIC increased significantly during and 60 minutes post-tDCS. The results indicate that transcranial direct current stimulation temporarily increases maximal isometric contractions of the internal and external rotators of the shoulder in handball players. 2.

  19. [Selective training of the vastus medialis muscle using electrical stimulator for chondromalacia patella].

    Science.gov (United States)

    Guo, K; Ye, Q; Lin, J; Shen, J; Yang, X

    1996-04-01

    Chondromalacia patella is closely related with subluxation and tilt of patella, as well as with muscular atrophy of quadriceps, especially in vastus medialis muscle. 364 cases of chondromalacia patella were treated with selective training of the vastus medialis muscle using electrical stimulator in our hospital. 211 cases were followed up after treatment from 6 months to 3 years. Among them excellent and good results were seen in 130 cases (62%), fair results were seen in 69 cases (33%) and no change was seen in 12 cases (5%). Significant reduction of CA (P chondromalacia patella.

  20. Skeletal muscle beta-receptors and isoproterenol-stimulated vasodilation in canine heart failure

    International Nuclear Information System (INIS)

    Frey, M.J.; Lanoce, V.; Molinoff, P.B.; Wilson, J.R.

    1989-01-01

    To investigate whether heart failure alters beta-adrenergic receptors on skeletal muscle and its associated vasculature, the density of beta-adrenergic receptors, isoproterenol-stimulated adenylate cyclase activity, and coupling of the guanine nucleotide-binding regulatory protein were compared in 18 control dogs and 16 dogs with heart failure induced by 5-8 wk of ventricular pacing at 260 beats/min. Hindlimb vascular responses to isoproterenol were compared in eight controls and eight of the dogs with heart failure. In dogs with heart failure, the density of beta-receptors on skeletal muscle was reduced in both gastrocnemius (control: 50 +/- 5; heart failure: 33 +/- 8 fmol/mg of protein) and semitendinosus muscle (control: 43 +/- 9; heart failure: 27 +/- 9 fmol/mg of protein, both P less than 0.05). Receptor coupling to the ternary complex, as determined by isoproterenol competition curves with and without guanosine 5'-triphosphate (GTP), was unchanged. Isoproterenol-stimulated adenylate cyclase activity was significantly decreased in semitendinosus muscle (control: 52.4 +/- 4.6; heart failure: 36.5 +/- 9.5 pmol.mg-1.min-1; P less than 0.05) and tended to be decreased in gastrocnemius muscle (control: 40.1 +/- 8.5; heart failure: 33.5 +/- 4.5 pmol.mg-1.min-1; P = NS). Isoproterenol-induced hindlimb vasodilation was not significantly different in controls and in dogs with heart failure. These findings suggest that heart failure causes downregulation of skeletal muscle beta-adrenergic receptors, probably due to receptor exposure to elevated catecholamine levels, but does not reduce beta-receptor-mediated vasodilation in muscle

  1. Electrical stimulation to the trigeminal proprioceptive fibres that innervate the mechanoreceptors in Müller's muscle induces involuntary reflex contraction of the frontalis muscles.

    Science.gov (United States)

    Matsuo, Kiyoshi; Osada, Yoshiro; Ban, Ryokuya

    2013-02-01

    The levator and frontalis muscles lack interior muscle spindles, despite consisting of slow-twitch fibres that involuntarily sustain eyelid-opening and eyebrow-raising against gravity. To compensate for this anatomical defect, this study hypothetically proposes that initial voluntary contraction of the levator fast-twitch muscle fibres stretches the mechanoreceptors in Müller's muscle and evokes proprioception, which continuously induces reflex contraction of slow-twitch fibres of the levator and frontalis muscles. This study sought to determine whether unilateral transcutaneous electrical stimulation to the trigeminal proprioceptive fibres that innervate the mechanoreceptors in Müller's muscle could induce electromyographic responses in the frontalis muscles, with monitoring responses in the orbicularis oculi muscles. The study population included 27 normal subjects and 23 subjects with aponeurotic blepharoptosis, who displayed persistently raised eyebrows on primary gaze and light eyelid closure. The stimulation induced a short-latency response in the ipsilateral frontalis muscle of all subjects and long-latency responses in the bilateral frontalis muscles of normal subjects. However, it did not induce long-latency responses in the bilateral frontalis muscles of subjects with aponeurotic blepharoptosis. The orbicularis oculi muscles showed R1 and/or R2 responses. The stimulation might reach not only the proprioceptive fibres, but also other sensory fibres related to the blink or corneal reflex. The experimental system can provoke a monosynaptic short-latency response in the ipsilateral frontalis muscle, probably through the mesencephalic trigeminal proprioceptive neuron and the frontalis motor neuron, and polysynaptic long-latency responses in the bilateral frontalis muscles through an unknown pathway. The latter neural circuit appeared to be engaged by the circumstances of aponeurotic blepharoptosis.

  2. Electrical muscle stimulation elevates intramuscular BDNF and GDNF mRNA following peripheral nerve injury and repair in rats.

    Science.gov (United States)

    Willand, Michael P; Rosa, Elyse; Michalski, Bernadeta; Zhang, Jennifer J; Gordon, Tessa; Fahnestock, Margaret; Borschel, Gregory H

    2016-10-15

    Despite advances in surgery, patients with nerve injuries frequently have functional deficits. We previously demonstrated in a rat model that daily electrical muscle stimulation (EMS) following peripheral nerve injury and repair enhances reinnervation, detectable as early as two weeks post-injury. In this study, we explain the enhanced early reinnervation observed with electrical stimulation. In two groups of rats, the tibial nerve was transected and immediately repaired. Gastrocnemius muscles were implanted with intramuscular electrodes for sham or muscle stimulation. Muscles were stimulated daily, eliciting 600 contractions for one hour/day, repeated five days per week. Sixteen days following nerve injury, muscles were assessed for functional reinnervation by motor unit number estimation methods using electromyographic recording. In a separate cohort of rats, surgical and electrical stimulation procedures were identical but muscles and distal nerve stumps were harvested for molecular analysis. We observed that stimulated muscles had significantly higher motor unit number counts. Intramuscular levels of brain-derived and glial cell line-derived neurotrophic factor (BDNF and GDNF) mRNA were significantly upregulated in muscles that underwent daily electrical stimulation compared to those without stimulation. The corresponding levels of trophic factor mRNA within the distal stump were not different from one another, indicating that the intramuscular electrical stimulus does not modulate Schwann cell-derived trophic factor transcription. Stimulation over a three-month period maintained elevated muscle-derived GDNF but not BDNF mRNA. In conclusion, EMS elevates intramuscular trophic factor mRNA levels which may explain how EMS enhances neural regeneration following nerve injury. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  3. Blood flow variation in human muscle during electrically stimulated exercise bouts.

    Science.gov (United States)

    Vanderthommen, Marc; Depresseux, Jean-Claude; Dauchat, Luc; Degueldre, Christian; Croisier, Jean-Louis; Crielaard, Jean-Michel

    2002-07-01

    To evaluate, with a high spatial resolution, the blood flow variations in human skeletal muscle during neuromuscular electric stimulation (NMES) and hence to gain better understanding of the mechanisms of muscle spatial recruitment during NMES. One thigh was submitted to 3 stimulation bouts of different durations (S1=4min, S2=8min, S3=12min) with a workload corresponding to 10% of quadriceps maximal isometric voluntary torque. A cyclotron research center at a Belgian university. Ten healthy male volunteers. Not applicable. Participants were studied with positron emission tomography and H(2)(15)O. Tissue blood flow was evaluated during the last 4 minutes of each stimulation bout in multiple regions of interest (ROIs) selected in the transverse section of the stimulated thigh. Mean tissue blood flow was significantly lower during S1 (5.9+/-1.3mL. min(-1). 100g(-1)) than during S2 (10.6+/-3.4mL. min(-1). 100g(-1)) and S3 (11.6+/-3.7mL. min(-1). 100g(-1)) (Precruited ROIs were preferentially located far from the electrode. During NMES, new muscular regions situated far from the stimulation site are recruited. These recruitment mechanisms are particular and contrast with the recruitment of motor units seen during voluntary contraction. Copyright 2002 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

  4. Na+,K+-pump stimulation improves contractility in isolated muscles of mice with hyperkalemic periodic paralysis.

    Science.gov (United States)

    Clausen, Torben; Nielsen, Ole Bækgaard; Clausen, Johannes D; Pedersen, Thomas Holm; Hayward, Lawrence J

    2011-07-01

    In patients with hyperkalemic periodic paralysis (HyperKPP), attacks of muscle weakness or paralysis are triggered by K(+) ingestion or rest after exercise. Force can be restored by muscle work or treatment with β(2)-adrenoceptor agonists. A missense substitution corresponding to a mutation in the skeletal muscle voltage-gated Na(+) channel (Na(v)1.4, Met1592Val) causing human HyperKPP was targeted into the mouse SCN4A gene (mutants). In soleus muscles prepared from these mutant mice, twitch, tetanic force, and endurance were markedly reduced compared with soleus from wild type (WT), reflecting impaired excitability. In mutant soleus, contractility was considerably more sensitive than WT soleus to inhibition by elevated [K(+)](o). In resting mutant soleus, tetrodotoxin (TTX)-suppressible (22)Na uptake and [Na(+)](i) were increased by 470 and 58%, respectively, and membrane potential was depolarized (by 16 mV, P Na(+),K(+) pump-mediated (86)Rb uptake was 83% larger than in WT. Salbutamol stimulated (86)Rb uptake and reduced [Na(+)](i) both in mutant and WT soleus. Stimulating Na(+),K(+) pumps with salbutamol restored force in mutant soleus and extensor digitorum longus (EDL). Increasing [Na(+)](i) with monensin also restored force in soleus. In soleus, EDL, and tibialis anterior muscles of mutant mice, the content of Na(+),K(+) pumps was 28, 62, and 33% higher than in WT, respectively, possibly reflecting the stimulating effect of elevated [Na(+)](i) on the synthesis of Na(+),K(+) pumps. The results confirm that the functional disorders of skeletal muscles in HyperKPP are secondary to increased Na(+) influx and show that contractility can be restored by acute stimulation of the Na(+),K(+) pumps. Calcitonin gene-related peptide (CGRP) restored force in mutant soleus but caused no detectable increase in (86)Rb uptake. Repeated excitation and capsaicin also restored contractility, possibly because of the release of endogenous CGRP from nerve endings in the isolated

  5. A REVIEW OF ELECTRICAL STIMULATION AND ITS EFFECT ON LINGUAL, LABIAL AND BUCCAL MUSCLE STRENGTH.

    Science.gov (United States)

    Safi, Mohammed F; Wright-Harp, Wilhelmina; Lucker, Jay R; Payne, Joan C; Harris, Ovetta

    2014-11-01

    Lingual, labial and buccal weakness (LLBW) is a widespread consequence of several neurological insults. LLBW impact on oral motor functions such as speech production and swallowing is well documented in the literature. Therefore, it is important for the speech-language pathologists to have access to evidence-based approaches for treatment. Thus, it is imperative that the speech-language pathology field search for effective treatment approaches and explore new treatment modalities that can improve therapy outcomes. One relatively new modality in this field is neuromuscular electrical stimulation (NMES). The purpose of this paper is fivefold: (a) to provide an overview of the general effects of NMES on skeletal muscles; (b) to review the effect of NMES on orofacial musculature evaluating the potential appropriateness of NMES for use in strengthening lingual, labial and buccal muscles; (c) to identify future directions for research with consideration of its potential role in improving speech intelligibility and the oral preparatory phase of swallowing in patients with oral motor weakness; (d) to provide a brief anatomic and physiologic bases of LLBW; (e) to provide background information for orofacial myologists who may encounter individuals with LLBW. NMES is a modality that is commonly used in physical therapy and occupational therapy fields that assists in treating several motor and sensory muscular disorders including muscular weakness. The literature reviewed demonstrate that very limited data related to the use of NMES on orofacial muscles exist despite the fact that these muscles can be easily accessed by electrical stimulation from the surface. This review of the research using electrical stimulation of muscles highlights the need for experimental treatment studies that investigate the effect of NMES on orofacial weakness.

  6. Isokinetic and isometric muscle strength combined with transcutaneous electrical muscle stimulation in primary fibromyalgia syndrome

    DEFF Research Database (Denmark)

    Jacobsen, Søren; Wildschiødtz, Gordon; Danneskiold-Samsøe, B

    1991-01-01

    Twenty women with primary fibromyalgia syndrome and 20 age matched healthy women were investigated. The subjects performed maximum voluntary isokinetic contractions of the right quadriceps in an isokinetic dynamometer. Maximum voluntary isometric contractions of the right quadriceps were performed...... of superimposed twitches was 65% in the patient group and 15% in the control group (p = 0.003). Patients with primary fibromyalgia have a lower maximum voluntary muscle strength than expected. The increased presence of superimposed electrically elicited twitches during maximum voluntary contraction indicates...... submaximal force application in primary fibromyalgia syndrome....

  7. 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

  8. 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...

  9. 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.

  10. Insulin-stimulated glucose uptake in healthy and insulin-resistant skeletal muscle

    DEFF Research Database (Denmark)

    Deshmukh, Atul S

    2016-01-01

    transporter protein 4 (GLUT4) to the plasma membrane which leads to facilitated diffusion of glucose into the cell. Understanding the precise signaling events guiding insulin-stimulated glucose uptake is pivotal, because impairment in these signaling events leads to development of insulin resistance and type...... 2 diabetes. This review summarizes current understanding of insulin signaling pathways mediating glucose uptake in healthy and insulin-resistant skeletal muscle....

  11. Optimal arrangement of magnetic coils for functional magnetic stimulation of the inspiratory muscles in dogs.

    Science.gov (United States)

    Lin, Vernon Weh-Hau; Zhu, Ercheng; Sasse, Scott A; Sassoon, Catherine; Hsiao, Ian N

    2005-12-01

    In an attempt to maximize inspiratory pressure and volume, the optimal position of a single or of dual magnetic coils during functional magnetic stimulation (FMS) of the inspiratory muscles was evaluated in twenty-three dogs. Unilateral phrenic magnetic stimulation (UPMS) or bilateral phrenic magnetic stimulation (BPMS), posterior cervical magnetic stimulation (PCMS), anterior cervical magnetic stimulation (ACMS) as well as a combination of PCMS and ACMS were performed. Trans-diaphragmatic pressure (Pdi), flow, and lung volume changes with an open airway were measured. Transdiaphragmatic pressure was also measured with an occluded airway. Changes in inspiratory parameters during FMS were compared with 1) electrical stimulation of surgically exposed bilateral phrenic nerves (BPES) and 2) ventral root electrical stimulation at C5-C7 (VRES C5-C7). Relative to the Pdi generated by BPES of 36.3 +/- 4.5 cm H2O (Mean +/- SEM), occluded Pdi(s) produced by UPMS, BPMS, PCMS, ACMS, and a combined PCMS + ACMS were 51.7%, 61.5%, 22.4%, 100.3%, and 104.5% of the maximal Pdi, respectively. Pdi(s) produced by UPMS, BPMS, PCMS, ACMS, and combined ACMS + PCMS were 38.0%, 45.2%, 16.5%, 73.8%, and 76.8%, respectively, of the Pdi induced by VRES (C5-C7) (48.0 +/- 3.9 cm H2O). The maximal Pdi(s) generated during ACMS and combined PCMS + ACMS were higher than the maximal Pdi(s) generated during UPMS, BPMS, or PCMS (p BPMS or PCMS. ACMS can be used to generate sufficient inspiratory pressure, flow, and volume for activation of the inspiratory muscles.

  12. Secretion of Growth Hormone in Response to Muscle Sensory Nerve Stimulation

    Science.gov (United States)

    Grindeland, Richard E.; Roy, R. R.; Edgerton, V. R.; Gosselink, K. L.; Grossman, E. J.; Sawchenko, P. E.; Wade, Charles E. (Technical Monitor)

    1994-01-01

    Growth hormone (GH) secretion is stimulated by aerobic and resistive exercise and inhibited by exposure to actual or simulated (bedrest, hindlimb suspension) microgravity. Moreover, hypothalamic growth hormone-releasing factor (GRF) and preproGRF mRNA are markedly decreased in spaceflight rats. These observations suggest that reduced sensory input from inactive muscles may contribute to the reduced secretion of GH seen in "0 G". Thus, the aim of this study was to determine the effect of muscle sensory nerve stimulation on secretion of GH. Fed male Wistar rats (304 +/- 23 g) were anesthetized (pentobarbital) and the right peroneal (Pe), tibial (T), and sural (S) nerves were cut. Electrical stimulation of the distal (D) or proximal (P) ends of the nerves was implemented for 15 min. to mimic the EMG activity patterns of ankle extensor muscles of a rat walking 1.5 mph. The rats were bled by cardiac puncture and their anterior pituitaries collected. Pituitary and plasma bioactive (BGH) and immunoactive (IGH) GH were measured by bioassay and RIA.

  13. Neuromuscular Electrical Stimulation for Treatment of Muscle Impairment: Critical Review and Recommendations for Clinical Practice

    Science.gov (United States)

    Houghton, Pamela; Anthony, Joseph; Rennie, Sandy; Shay, Barbara L.; Hoens, Alison M.

    2017-01-01

    Purpose: In response to requests from physiotherapists for guidance on optimal stimulation of muscle using neuromuscular electrical stimulation (NMES), a review, synthesis, and extraction of key data from the literature was undertaken by six Canadian physical therapy (PT) educators, clinicians, and researchers in the field of electrophysical agents. The objective was to identify commonly treated conditions for which there was a substantial body of literature from which to draw conclusions regarding the effectiveness of NMES. Included studies had to apply NMES with visible and tetanic muscle contractions. Method: Four electronic databases (CINAHL, Embase, PUBMED, and SCOPUS) were searched for relevant literature published between database inceptions until May 2015. Additional articles were identified from bibliographies of the systematic reviews and from personal collections. Results: The extracted data were synthesized using a consensus process among the authors to provide recommendations for optimal stimulation parameters and application techniques to address muscle impairments associated with the following conditions: stroke (upper or lower extremity; both acute and chronic), anterior cruciate ligament reconstruction, patellofemoral pain syndrome, knee osteoarthritis, and total knee arthroplasty as well as critical illness and advanced disease states. Summaries of key details from each study incorporated into the review were also developed. The final sections of the article outline the recommended terminology for describing practice using electrical currents and provide tips for safe and effective clinical practice using NMES. Conclusion: This article provides physiotherapists with a resource to enable evidence-informed, effective use of NMES for PT practice. PMID:29162949

  14. A Biological Micro Actuator: Graded and Closed-Loop Control of Insect Leg Motion by Electrical Stimulation of Muscles

    Science.gov (United States)

    Cao, Feng; Zhang, Chao; Vo Doan, Tat Thang; Li, Yao; Sangi, Daniyal Haider; Koh, Jie Sheng; Huynh, Ngoc Anh; Aziz, Mohamed Fareez Bin; Choo, Hao Yu; Ikeda, Kazuo; Abbeel, Pieter; Maharbiz, Michel M.; Sato, Hirotaka

    2014-01-01

    In this study, a biological microactuator was demonstrated by closed-loop motion control of the front leg of an insect (Mecynorrhina torquata, beetle) via electrical stimulation of the leg muscles. The three antagonistic pairs of muscle groups in the front leg enabled the actuator to have three degrees of freedom: protraction/retraction, levation/depression, and extension/flexion. We observed that the threshold amplitude (voltage) required to elicit leg motions was approximately 1.0 V; thus, we fixed the stimulation amplitude at 1.5 V to ensure a muscle response. The leg motions were finely graded by alternation of the stimulation frequencies: higher stimulation frequencies elicited larger leg angular displacement. A closed-loop control system was then developed, where the stimulation frequency was the manipulated variable for leg-muscle stimulation (output from the final control element to the leg muscle) and the angular displacement of the leg motion was the system response. This closed-loop control system, with an optimized proportional gain and update time, regulated the leg to set at predetermined angular positions. The average electrical stimulation power consumption per muscle group was 148 µW. These findings related to and demonstrations of the leg motion control offer promise for the future development of a reliable, low-power, biological legged machine (i.e., an insect–machine hybrid legged robot). PMID:25140875

  15. A biological micro actuator: graded and closed-loop control of insect leg motion by electrical stimulation of muscles.

    Directory of Open Access Journals (Sweden)

    Feng Cao

    Full Text Available In this study, a biological microactuator was demonstrated by closed-loop motion control of the front leg of an insect (Mecynorrhina torquata, beetle via electrical stimulation of the leg muscles. The three antagonistic pairs of muscle groups in the front leg enabled the actuator to have three degrees of freedom: protraction/retraction, levation/depression, and extension/flexion. We observed that the threshold amplitude (voltage required to elicit leg motions was approximately 1.0 V; thus, we fixed the stimulation amplitude at 1.5 V to ensure a muscle response. The leg motions were finely graded by alternation of the stimulation frequencies: higher stimulation frequencies elicited larger leg angular displacement. A closed-loop control system was then developed, where the stimulation frequency was the manipulated variable for leg-muscle stimulation (output from the final control element to the leg muscle and the angular displacement of the leg motion was the system response. This closed-loop control system, with an optimized proportional gain and update time, regulated the leg to set at predetermined angular positions. The average electrical stimulation power consumption per muscle group was 148 µW. These findings related to and demonstrations of the leg motion control offer promise for the future development of a reliable, low-power, biological legged machine (i.e., an insect-machine hybrid legged robot.

  16. Intraoperative muscle electrical stimulation for accurate positioning of the temporalis muscle tendon during dynamic, one-stage lengthening temporalis myoplasty for facial and lip reanimation.

    Science.gov (United States)

    Har-Shai, Yaron; Gil, Tamir; Metanes, Issa; Labbé, Daniel

    2010-07-01

    Facial paralysis is a significant functional and aesthetic handicap. Facial reanimation is performed either by two-stage microsurgical methods or by regional one-stage muscle pedicle flaps. Labbé has modified and improved the regional muscle pedicle transfer flaps for facial reanimation (i.e., the lengthening temporalis myoplasty procedure). This true myoplasty technique is capable of producing a coordinated, spontaneous, and symmetrical smile. An intraoperative electrical stimulation of the temporal muscle is proposed to simulate the smile of the paralyzed side on the surgical table. The intraoperative electrical stimulation of the temporalis muscle, employing direct percutaneous electrode needles or transcutaneous electrical stimulation electrodes, was utilized in 11 primary and four secondary cases with complete facial palsy. The duration of the facial paralysis was up to 12 years. Postoperative follow-up ranged from 3 to 12 months. The insertion points of the temporalis muscle tendon to the nasolabial fold, upper lip, and oral commissure had been changed according to the intraoperative muscle stimulation in six patients of the 11 primary cases (55 percent) and in all four secondary (revisional) cases. A coordinated, spontaneous, and symmetrical smile was achieved in all patients by 3 months after surgery by employing speech therapy and biofeedback. This adjunct intraoperative refinement provides crucial feedback for the surgeon in both primary and secondary facial palsy cases regarding the vector of action of the temporalis muscle and the accuracy of the anchoring points of its tendon, thus enhancing a more coordinated and symmetrical smile.

  17. 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.

  18. 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.

  19. Effect of transcranial direct current stimulation on neuroplasticity in corticomotor pathways of the tongue muscles

    DEFF Research Database (Denmark)

    Kothari, Mohit; Stubbs, Peter William; Figlewski, Krystian

    2017-01-01

    To investigate effects of transcranial direct current stimulation (tDCS) on neuroplasticity in corticomotor pathways related to tongue muscles evoked by a training task using the Tongue Drive System (TDS). Using a cross-over design, 13 healthy participants completed two sessions of tDCS while...... performing 30 min of TDS training. Sessions were spaced at least 2 weeks apart and participants randomly received anodal and sham tDCS stimulation in the first session and the other condition in the second session. Single and paired pulse transcranial magnetic stimulation was used to elicit motor evoked...... potentials (MEPs) of the tongue at three time-points; before, immediately after and 30 min after training. Participant-based reports of fun, pain, fatigue and motivation, level of difficulty and effort were evaluated on numerical rating scales. There was no consistent significant effect of anodal and sham...

  20. TIMP-1 stimulates proliferation of human aortic smooth muscle cells and Ras effector pathways

    International Nuclear Information System (INIS)

    Akahane, Takemi; Akahane, Manabu; Shah, Amy; Thorgeirsson, Unnur P.

    2004-01-01

    Tissue inhibitor of metalloproteinases-1 (TIMP-1) is a multifunctional protein, which is found in most tissues and body fluids. Here, we demonstrated that recombinant TIMP-1 but not the synthetic matrix metalloproteinase inhibitor, GM6001, stimulated proliferation of human aortic smooth muscle cells (AoSMC) in a dose-dependent manner. The mitogenic effect was associated with activation of Ras, increased phosphorylation of ERK, and stimulation of cyclin D1 expression. The phosphatidylinositol 3-kinase (PI3K) signaling pathway was also involved since the PI3K inhibitor, LY294002, abolished the TIMP-1-mediated growth stimulation. These data suggest that TIMP-1 activates Ras, which then turns on the ERK and PI3K signaling pathways to promote cell cycle progression of the AoSMC

  1. Video game-based neuromuscular electrical stimulation system for calf muscle training: a case study.

    Science.gov (United States)

    Sayenko, D G; Masani, K; Milosevic, M; Robinson, M F; Vette, A H; McConville, K M V; Popovic, M R

    2011-03-01

    A video game-based training system was designed to integrate neuromuscular electrical stimulation (NMES) and visual feedback as a means to improve strength and endurance of the lower leg muscles, and to increase the range of motion (ROM) of the ankle joints. The system allowed the participants to perform isotonic concentric and isometric contractions in both the plantarflexors and dorsiflexors using NMES. In the proposed system, the contractions were performed against exterior resistance, and the angle of the ankle joints was used as the control input to the video game. To test the practicality of the proposed system, an individual with chronic complete spinal cord injury (SCI) participated in the study. The system provided a progressive overload for the trained muscles, which is a prerequisite for successful muscle training. The participant indicated that he enjoyed the video game-based training and that he would like to continue the treatment. The results show that the training resulted in a significant improvement of the strength and endurance of the paralyzed lower leg muscles, and in an increased ROM of the ankle joints. Video game-based training programs might be effective in motivating participants to train more frequently and adhere to otherwise tedious training protocols. It is expected that such training will not only improve the properties of their muscles but also decrease the severity and frequency of secondary complications that result from SCI. Copyright © 2010 IPEM. All rights reserved.

  2. Postfatigue potentiation of the paralyzed soleus muscle: evidence for adaptation with long-term electrical stimulation training

    OpenAIRE

    Shields, Richard K.; Dudley-Javoroski, Shauna; Littmann, Andrew E.

    2006-01-01

    Understanding the torque output behavior of paralyzed muscle has important implications for the use of functional neuromuscular electrical stimulation systems. Postfatigue potentiation is an augmentation of peak muscle torque during repetitive activation after a fatigue protocol. The purposes of this study were 1) to quantify postfatigue potentiation in the acutely and chronically paralyzed soleus and 2) to determine the effect of long-term soleus electrical stimulation training on the potent...

  3. Phospholemman is not required for the acute stimulation of Na+-K+-ATPase α2-activity during skeletal muscle fatigue

    Science.gov (United States)

    Manoharan, Palanikumar; Radzyukevich, Tatiana L.; Hakim Javadi, Hesamedin; Stiner, Cory A.; Landero Figueroa, Julio A.; Lingrel, Jerry B

    2015-01-01

    The Na+-K+-ATPase α2-isoform in skeletal muscle is rapidly stimulated during muscle use and plays a critical role in fatigue resistance. The acute mechanisms that stimulate α2-activity are not completely known. This study examines whether phosphorylation of phospholemman (PLM/FXYD1), a regulatory subunit of Na+-K+-ATPase, plays a role in the acute stimulation of α2 in working muscles. Mice lacking PLM (PLM KO) have a normal content of the α2-subunit and show normal exercise capacity, in contrast to the greatly reduced exercise capacity of mice that lack α2 in the skeletal muscles. Nerve-evoked contractions in vivo did not induce a change in total PLM or PLM phosphorylated at Ser63 or Ser68, in either WT or PLM KO. Isolated muscles of PLM KO mice maintain contraction and resist fatigue as well as wild type (WT). Rb+ transport by the α2-Na+-K+-ATPase is stimulated to the same extent in contracting WT and contracting PLM KO muscles. Phosphorylation of sarcolemmal membranes prepared from WT but not PLM KO skeletal muscles stimulates the activity of both α1 and α2 in a PLM-dependent manner. The stimulation occurs by an increase in Na+ affinity without significant change in Vmax and is more effective for α1 than α2. These results demonstrate that phosphorylation of PLM is capable of stimulating the activity of both isozymes in skeletal muscle; however, contractile activity alone is not sufficient to induce PLM phosphorylation. Importantly, acute stimulation of α2, sufficient to support exercise and oppose fatigue, does not require PLM or its phosphorylation. PMID:26468207

  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. Alternate rhythmic vibratory stimulation of trunk muscles affects walking cadence and velocity in Parkinson's disease.

    Science.gov (United States)

    De Nunzio, Alessandro M; Grasso, Margherita; Nardone, Antonio; Godi, Marco; Schieppati, Marco

    2010-02-01

    During the administration of timed bilateral alternate vibration to homonymous leg or trunk muscles during quiet upright stance, Parkinsonian (PD) patients undergo cyclic antero-posterior and medio-lateral transfers of the centre of foot pressure. This event might be potentially exploited for improving gait in these patients. Here, we tested this hypothesis by applying alternate muscle vibration during walking in PD. Fifteen patients and 15 healthy subjects walked on an instrumented walkway under four conditions: no vibration (no-Vib), and vibration of tibialis anterior (TA-Vib), soleus (Sol-Vib) and erector spinae (ES-Vib) muscles of both sides. Trains of vibration (internal frequency 100 Hz) were delivered to right and left side at alternating frequency of 10% above preferred step cadence. During vibration, stride length, cadence and velocity increased in both patients and healthy subjects, significantly so for ES-Vib. Stance and swing time tended to decrease. Width of support base increased with Sol-Vib or TA-Vib, but was unaffected by ES-Vib. Alternate ES vibration enhances gait velocity in PD. The stronger effect of ES over leg muscle vibration might depend on the relevance of the proprioceptive inflow from the trunk muscles and on the absence of adverse effects on the support base width. Trunk control is defective in PD. The effect of timed vibratory stimulation on gait suggests the potential use of trunk proprioceptive stimulation for tuning the central pattern generators for locomotion in PD. Copyright (c) 2009 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  6. Ischaemia and insulin, but not ischaemia and contraction, act synergistically in stimulating muscle glucose uptake in vivo in humans.

    NARCIS (Netherlands)

    Bosselaar, M.; Smits, P.; Tack, C.J.J.

    2009-01-01

    Ischaemia, like muscle contraction, has been reported to induce skeletal muscle glucose uptake in in vitro models. This stimulating effect appears independent of insulin and is probably mediated by activation of AMPK (AMP-activated protein kinase). In the present study, we hypothesized that in vivo

  7. Advanced maturation by electrical stimulation : differences in response between C2C12 and primary muscle progenitor cells

    NARCIS (Netherlands)

    Langelaan, M.L.P.; Boonen, K.J.M.; Rosaria-Chak, K.Y.; Schaft, van der D.W.J.; Post, M.J.; Baaijens, F.P.T.

    2011-01-01

    Skeletal muscle tissue engineering still does not result in the desired functional properties and texture as preferred for regenerative medicine and meat production applications. Electrical stimulation has been appropriately used as a tool to advance muscle cell maturation in vitro, thereby

  8. Cooperation of electrically stimulated muscle and pneumatic muscle to realize RUPERT bi-directional motion for grasping.

    Science.gov (United States)

    Xikai Tu; Jiping He; Yue Wen; Jian Huang; Xinhan Huang; Hailong Huang; Meng Guo; Yong Yuan

    2014-01-01

    Robot-assisted rehabilitation is an active area of research to meet the demand of repetitive therapy in stroke rehabilitation. Robotic upper-extremity repetitive trainer (RUPERT) with its unidirectional pneumatic muscle actuation (PMA) can be used by most stroke patients that have difficulty moving in one direction because of a weak agonist or hyperactive antagonist. In this research, to broaden the usage of RUPERT, we not only add grasping functionality to the rehabilitation robot with the help of surface Functional Electrical Stimulation (FES) but also realize the robot joint bi-directional motion by using a PMA in cooperation with surface FES evoked paralyzed muscle force. This integrative rehabilitation strategy is explored for training patients to practice coordinated reaching and grasping functions. The effectiveness of this FES electrically evoked bio-actuator way is verified through a method that separates the mixed electromyogram (MEMG) into the electrically evoked electromyogram (EEMG) and voluntary electromyogram (VEMG). This is a promising approach to alleviate the size and mechanical complexity of the robot, thereby the cost of the joint bi-directional actuator rehabilitation robot by means of their own characteristics of stroke subjects.

  9. Transcranial direct current stimulation does not affect lower extremity muscle strength training in healthy individuals

    DEFF Research Database (Denmark)

    Maeda, Kazuhei; Yamaguchi, Tomofumi; Tatemoto, Tsuyoshi

    2017-01-01

    The present study investigated the effects of anodal transcranial direct current stimulation (tDCS) on lower extremity muscle strength training in 24 healthy participants. In this triple-blind, sham-controlled study, participants were randomly allocated to the anodal tDCS plus muscle strength...... training (anodal tDCS) group or sham tDCS plus muscle strength training (sham tDCS) group. Anodal tDCS (2 mA) was applied to the primary motor cortex of the lower extremity during muscle strength training of the knee extensors and flexors. Training was conducted once every 3 days for 3 weeks (7 sessions......). Knee extensor and flexor peak torques were evaluated before and after the 3 weeks of training. After the 3-week intervention, peak torques of knee extension and flexion changed from 155.9 to 191.1 Nm and from 81.5 to 93.1 Nm in the anodal tDCS group. Peak torques changed from 164.1 to 194.8 Nm...

  10. IGF1 stimulates greater muscle hypertrophy in the absence of myostatin in male mice.

    Science.gov (United States)

    Hennebry, Alexander; Oldham, Jenny; Shavlakadze, Tea; Grounds, Miranda D; Sheard, Philip; Fiorotto, Marta L; Falconer, Shelley; Smith, Heather K; Berry, Carole; Jeanplong, Ferenc; Bracegirdle, Jeremy; Matthews, Kenneth; Nicholas, Gina; Senna-Salerno, Mônica; Watson, Trevor; McMahon, Christopher D

    2017-08-01

    Insulin-like growth factors (IGFs) and myostatin have opposing roles in regulating the growth and size of skeletal muscle, with IGF1 stimulating, and myostatin inhibiting, growth. However, it remains unclear whether these proteins have mutually dependent, or independent, roles. To clarify this issue, we crossed myostatin null ( Mstn -/- ) mice with mice overexpressing Igf1 in skeletal muscle ( Igf1 + ) to generate six genotypes of male mice; wild type ( Mstn +/+ ), Mstn +/- , Mstn -/- , Mstn +/+ :Igf1 + , Mstn +/- :Igf1 + and Mstn -/- :Igf1 + Overexpression of Igf1 increased the mass of mixed fibre type muscles (e.g. Quadriceps femoris ) by 19% over Mstn +/+ , 33% over Mstn +/- and 49% over Mstn -/- ( P  Myostatin regulated the number, while IGF1 regulated the size of myofibres, and the deletion of Mstn and Igf1 + independently increased the proportion of fast type IIB myosin heavy chain isoforms in T. anterior (up to 10% each, P  myostatin is absent and IGF1 is in excess. Finally, we show that myostatin and IGF1 regulate skeletal muscle size, myofibre type and gonadal fat through distinct mechanisms that involve increasing the total abundance and phosphorylation status of AKT and rpS6. © 2017 Society for Endocrinology.

  11. Spatial factors and muscle spindle input influence the generation of neuromuscular responses to stimulation of the human foot

    Science.gov (United States)

    Layne, Charles S.; Forth, Katharine E.; Abercromby, Andrew F. J.

    2005-05-01

    Removal of the mechanical pressure gradient on the soles leads to physiological adaptations that ultimately result in neuromotor degradation during spaceflight. We propose that mechanical stimulation of the soles serves to partially restore the afference associated with bipedal loading and assists in attenuating the negative neuromotor consequences of spaceflight. A dynamic foot stimulus device was used to stimulate the soles in a variety of conditions with different stimulation locations, stimulation patterns and muscle spindle input. Surface electromyography revealed the lateral side of the sole elicited the greatest neuromuscular response in ankle musculature, followed by the medial side, then the heel. These responses were modified by preceding stimulation. Neuromuscular responses were also influenced by the level of muscle spindle input. These results provide important information that can be used to guide the development of a "passive" countermeasure that relies on sole stimulation and can supplement existing exercise protocols during spaceflight.

  12. Effects of the belt electrode skeletal muscle electrical stimulation system on lower extremity skeletal muscle activity: Evaluation using positron emission tomography.

    Science.gov (United States)

    Numata, Hitoaki; Nakase, Junsuke; Inaki, Anri; Mochizuki, Takafumi; Oshima, Takeshi; Takata, Yasushi; Kinuya, Seigo; Tsuchiya, Hiroyuki

    2016-01-01

    Lower-extremity muscle weakness in athletes after lower limb trauma or surgery can hinder their return to sports, and the associated muscle atrophy may lead to deterioration in performance after returning to sports. Recently, belt electrode skeletal muscle electrical stimulation (B-SES) which can contract all the lower limb skeletal muscles simultaneously was developed. However, no study has evaluated skeletal muscle activity with B-SES. Since only superficial muscles as well as a limited number of muscles can be investigated using electromyography, we investigated whether positron emission tomography (PET) can evaluate the activity of all the skeletal muscles in the body simultaneously. The purpose of this study was to evaluate the effectiveness of the B-SES system using PET. Twelve healthy males (mean age, 24.3 years) were divided into two groups. The subjects in the control group remained in a sitting position for 10 min, and [(18)F] fluorodeoxyglucose (FDG) was intravenously injected. In the exercise group, subjects exercised using the B-SES system for 20 min daily for three consecutive days as a pre-test exercise. On the measurement day, they exercised for 10 min, received an injection of FDG, and exercised for another 10 min. PET-computed tomography images were obtained in each group 60 min after the FDG injection. Regions of interest were drawn in each lower-extremity muscle. We compared each skeletal muscle metabolism using the standardized uptake value. In the exercise group, FDG accumulation in the gluteus maximus, gluteus medius, gluteus minimus, quadriceps femoris, sartorius, and hamstrings was significantly higher than the muscles in the control (P skeletal muscle activity of the gluteal muscles as well as the most lower-extremity muscles simultaneously. Copyright © 2015 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.

  13. Rac1 and AMPK account for the majority of muscle glucose uptake stimulated by ex vivo contraction but not in vivo exercise

    DEFF Research Database (Denmark)

    Sylow, Lykke; Møller, Lisbeth Liliendal Valbjørn; Kleinert, Maximilian

    2017-01-01

    Exercise bypasses insulin resistance to increase glucose uptake in skeletal muscle and therefore represents an important alternative to stimulate glucose uptake in insulin resistant muscle. Both Rac1 and AMPK have been shown to partly regulate contraction-stimulated muscle glucose uptake but whet...

  14. Control of thumb force using surface functional electrical stimulation and muscle load sharing

    Science.gov (United States)

    2013-01-01

    Background Stroke survivors often have difficulties in manipulating objects with their affected hand. Thumb control plays an important role in object manipulation. Surface functional electrical stimulation (FES) can assist movement. We aim to control the 2D thumb force by predicting the sum of individual muscle forces, described by a sigmoidal muscle recruitment curve and a single force direction. Methods Five able bodied subjects and five stroke subjects were strapped in a custom built setup. The forces perpendicular to the thumb in response to FES applied to three thumb muscles were measured. We evaluated the feasibility of using recruitment curve based force vector maps in predicting output forces. In addition, we developed a closed loop force controller. Load sharing between the three muscles was used to solve the redundancy problem having three actuators to control forces in two dimensions. The thumb force was controlled towards target forces of 0.5 N and 1.0 N in multiple directions within the individual’s thumb work space. Hereby, the possibilities to use these force vector maps and the load sharing approach in feed forward and feedback force control were explored. Results The force vector prediction of the obtained model had small RMS errors with respect to the actual measured force vectors (0.22±0.17 N for the healthy subjects; 0.17±0.13 N for the stroke subjects). The stroke subjects showed a limited work range due to limited force production of the individual muscles. Performance of feed forward control without feedback, was better in healthy subjects than in stroke subjects. However, when feedback control was added performances were similar between the two groups. Feedback force control lead, especially for the stroke subjects, to a reduction in stationary errors, which improved performance. Conclusions Thumb muscle responses to FES can be described by a single force direction and a sigmoidal recruitment curve. Force in desired direction can be

  15. Skeletal Muscle-specific G Protein-coupled Receptor Kinase 2 Ablation Alters Isolated Skeletal Muscle Mechanics and Enhances Clenbuterol-stimulated Hypertrophy.

    Science.gov (United States)

    Woodall, Benjamin P; Woodall, Meryl C; Luongo, Timothy S; Grisanti, Laurel A; Tilley, Douglas G; Elrod, John W; Koch, Walter J

    2016-10-14

    GRK2, a G protein-coupled receptor kinase, plays a critical role in cardiac physiology. Adrenergic receptors are the primary target for GRK2 activity in the heart; phosphorylation by GRK2 leads to desensitization of these receptors. As such, levels of GRK2 activity in the heart directly correlate with cardiac contractile function. Furthermore, increased expression of GRK2 after cardiac insult exacerbates injury and speeds progression to heart failure. Despite the importance of this kinase in both the physiology and pathophysiology of the heart, relatively little is known about the role of GRK2 in skeletal muscle function and disease. In this study we generated a novel skeletal muscle-specific GRK2 knock-out (KO) mouse (MLC-Cre:GRK2 fl/fl ) to gain a better understanding of the role of GRK2 in skeletal muscle physiology. In isolated muscle mechanics testing, GRK2 ablation caused a significant decrease in the specific force of contraction of the fast-twitch extensor digitorum longus muscle yet had no effect on the slow-twitch soleus muscle. Despite these effects in isolated muscle, exercise capacity was not altered in MLC-Cre:GRK2 fl/fl mice compared with wild-type controls. Skeletal muscle hypertrophy stimulated by clenbuterol, a β 2 -adrenergic receptor (β 2 AR) agonist, was significantly enhanced in MLC-Cre:GRK2 fl/fl mice; mechanistically, this seems to be due to increased clenbuterol-stimulated pro-hypertrophic Akt signaling in the GRK2 KO skeletal muscle. In summary, our study provides the first insights into the role of GRK2 in skeletal muscle physiology and points to a role for GRK2 as a modulator of contractile properties in skeletal muscle as well as β 2 AR-induced hypertrophy. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  16. Skeletal Muscle-specific G Protein-coupled Receptor Kinase 2 Ablation Alters Isolated Skeletal Muscle Mechanics and Enhances Clenbuterol-stimulated Hypertrophy*

    Science.gov (United States)

    Woodall, Benjamin P.; Woodall, Meryl C.; Luongo, Timothy S.; Grisanti, Laurel A.; Tilley, Douglas G.; Elrod, John W.; Koch, Walter J.

    2016-01-01

    GRK2, a G protein-coupled receptor kinase, plays a critical role in cardiac physiology. Adrenergic receptors are the primary target for GRK2 activity in the heart; phosphorylation by GRK2 leads to desensitization of these receptors. As such, levels of GRK2 activity in the heart directly correlate with cardiac contractile function. Furthermore, increased expression of GRK2 after cardiac insult exacerbates injury and speeds progression to heart failure. Despite the importance of this kinase in both the physiology and pathophysiology of the heart, relatively little is known about the role of GRK2 in skeletal muscle function and disease. In this study we generated a novel skeletal muscle-specific GRK2 knock-out (KO) mouse (MLC-Cre:GRK2fl/fl) to gain a better understanding of the role of GRK2 in skeletal muscle physiology. In isolated muscle mechanics testing, GRK2 ablation caused a significant decrease in the specific force of contraction of the fast-twitch extensor digitorum longus muscle yet had no effect on the slow-twitch soleus muscle. Despite these effects in isolated muscle, exercise capacity was not altered in MLC-Cre:GRK2fl/fl mice compared with wild-type controls. Skeletal muscle hypertrophy stimulated by clenbuterol, a β2-adrenergic receptor (β2AR) agonist, was significantly enhanced in MLC-Cre:GRK2fl/fl mice; mechanistically, this seems to be due to increased clenbuterol-stimulated pro-hypertrophic Akt signaling in the GRK2 KO skeletal muscle. In summary, our study provides the first insights into the role of GRK2 in skeletal muscle physiology and points to a role for GRK2 as a modulator of contractile properties in skeletal muscle as well as β2AR-induced hypertrophy. PMID:27566547

  17. Functional Magnetic Stimulation of Inspiratory and Expiratory Muscles in Subjects With Tetraplegia.

    Science.gov (United States)

    Zhang, Xiaoming; Plow, Ela; Ranganthan, Vinoth; Huang, Honglian; Schmitt, Melissa; Nemunaitis, Gregory; Kelly, Clay; Frost, Frederick; Lin, Vernon

    2016-07-01

    Respiratory complications are major causes of morbidity and mortality in persons with a spinal cord injury, partly because of respiratory muscle paralysis. Earlier investigation has demonstrated that functional magnetic stimulation (FMS) can be used as a noninvasive technology for activating expiratory muscles, thus producing useful expiratory functions (simulated cough) in subjects with spinal cord injury. To evaluate the effectiveness of FMS for conditioning inspiratory and expiratory muscles in persons with tetraplegia. A prospective before and after trial. FMS Laboratory, Louis Stokes Cleveland VA Medical Center, Cleveland, OH. Six persons with tetraplegia. Each subject participated in a 6-week FMS protocol for conditioning the inspiratory and expiratory muscles. A magnetic stimulator was used with the center of a magnetic coil placed at the C7-T1 and T9-T10 spinous processes, respectively. Pulmonary function tests were performed before, during, and after the protocol. Respiratory variables included maximal inspiratory pressure (MIP), inspiratory reserve volume (IRV), peak inspiratory flow (PIF), maximal expiratory pressure (MEP), expiratory reserve volume (ERV), and peak expiratory flow (PEF). After 6 weeks of conditioning, the main outcome measurements (mean ± standard error) were as follows: MIP, 89.6 ± 7.3 cm H2O; IRV, 1.90 ± 0.34 L; PIF, 302.4 ± 36.3 L/min; MEP, 67.4 ± 11.1 cm H2O; ERV, 0.40 ± 0.06 L; and PEF, 372.4 ± 31.9 L/min. These values corresponded to 117%, 107%, 136%, 109%, 130%, and 124% of pre-FMS conditioning values, respectively. Significant improvements were observed in MIP (P = .022), PIF (P = .0001), and PEF (P = .0006), respectively. When FMS was discontinued for 4 weeks, these values showed decreases from their values at the end of the conditioning protocol, which suggests that continual FMS may be necessary to maintain improved respiratory functions. FMS conditioning of the inspiratory and expiratory muscles improved

  18. Effects of transcutaneous electrical stimulation of lower limb muscles on experimental fatty liver.

    Science.gov (United States)

    El-Kafoury, Bataa M; Seif, Ansam A; El-Aziz Abd El-Hady, Enas A; El-Sebaiee, Ahmed E

    2016-03-01

    Although the beneficial effects of exercise on fatty liver have been described, a previous study conducted at our department showed that transcutaneous electrical muscle stimulation (TEMS) of lower abdominal muscles aggravated fatty liver. The present study aims to evaluate the ability of TEMS of the lower limb muscles to improve fatty liver infiltration. Thirty male Wistar rats were randomly allocated into three groups: control; fructose-fed (F), fed fructose-enriched diet for 6weeks; and fructose-fed with transcutaneous electrical muscle stimulation (F+TEMS), fed fructose-enriched diet for 6weeks and lower limb muscles subjected to TEMS during the last 3weeks of feeding, five sessions/week. Body weight, length, body mass index (BMI), and abdominal and lower limb circumferences were all recorded. Fasting blood glucose, serum insulin, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), total protein, serum albumin, high density lipoprotein cholesterol (HDL-C), triglyceride (TG), and total cholesterol (TC) levels were measured. LDL cholesterol (LDL-C) and the atherogenic index (AI) were calculated. Absolute and relative hepatic weights as well as histological examination of the liver were assessed. Final body weight, abdominal and lower limb circumferences, absolute liver weight, homoeostasis model assessment (HOMA) score, and TG, LDL-C, AI, serum ALT, and AST levels were all significantly reduced in the (F+TEMS) group compared to the (F) group. There was a significant increase in GPx and HDL-C levels, HDL/LDL ratio, and total protein and serum albumin content in (F+TEMS) rats compared to (F) rats. Histologically, hepatic tissue from (F+TEMS) rats had minimal steatotic changes that were restricted to zone 1 and less marked inflammatory cell infiltration compared to (F) rats. TEMS was able to reverse steatosis, hyperglycaemia, insulin resistance, dyslipidaemia, and fatty liver caused by fructose feeding. The study confirmed that the variation in

  19. Multi-muscle electrical stimulation and stand training: Effects on standing.

    Science.gov (United States)

    Momeni, Kamyar; Ramanujam, Arvind; Garbarini, Erica L; Forrest, Gail F

    2018-02-15

    To examine the biomechanical and neuromuscular effects of a longitudinal multi-muscle electrical stimulation (submaximal intensities) training of the lower limbs combined with/without activity-based stand training, on the recovery of stability and function for one individual with spinal cord injury (SCI). Single-subject, longitudinal study. Neuroplasticity laboratory. A 34-year-old male, with sensory- and motor-complete SCI (C5/C6). Two consecutive interventions: 61 hours of supine, lower-limb ES (ES-alone) and 51 hours of ES combined with stand training using an overhead body-weight support system (ST + ES). Clinical measures, trunk stability, and muscle activity were assessed and compared across time points. Trunk Stability Limit (TSL) determined improvements in trunk independence. Functional clinical values increased after both interventions, with further increases post ST + ES. Post ES-alone, trunk stability was maintained at 81% body-weight (BW) loading before failure; post ST + ES, BW loading increased to 95%. TSL values decreased post ST + ES (TSL A/P =54.0 kg.cm, TSL M/L =14.5 kg.cm), compared to ES-alone (TSL A/P =8.5 kg.cm, TSL M/L =3.9 kg.cm). Trunk muscle activity decreased post ST + ES training, compared to ES-alone. Neuromuscular and postural trunk control dramatically improved following the multi-muscle ES of the lower limbs with stand training. Multi-muscle ES training paradigm of the lower limb, using traditional parameters, may contribute to the functional recovery of the trunk.

  20. Neuromuscular electrical stimulation prior to presleep protein feeding stimulates the use of protein-derived amino acids for overnight muscle protein synthesis.

    Science.gov (United States)

    Dirks, Marlou L; Groen, Bart B L; Franssen, Rinske; van Kranenburg, Janneau; van Loon, Luc J C

    2017-01-01

    Short periods of muscle disuse result in substantial skeletal muscle atrophy. Recently, we showed that both neuromuscular electrical stimulation (NMES) as well as presleep dietary protein ingestion represent effective strategies to stimulate muscle protein synthesis rates. In this study, we test our hypothesis that NMES can augment the use of presleep protein-derived amino acids for overnight muscle protein synthesis in older men. Twenty healthy, older [69 ± 1 (SE) yr] men were subjected to 24 h of bed rest, starting at 8:00 AM. In the evening, volunteers were subjected to 70-min 1-legged NMES, while the other leg served as nonstimulated control (CON). Immediately following NMES, 40 g of intrinsically l-[1- 13 C]-phenylalanine labeled protein was ingested prior to sleep. Blood samples were taken throughout the night, and muscle biopsies were obtained from both legs in the evening and the following morning (8 h after protein ingestion) to assess dietary protein-derived l-[1- 13 C]-phenylalanine enrichments in myofibrillar protein. Plasma phenylalanine concentrations and plasma l-[1- 13 C]-phenylalanine enrichments increased significantly following protein ingestion and remained elevated for up to 6 h after protein ingestion (P protein-bound l-[1- 13 C]-phenylalanine enrichments (MPE) increased to a greater extent in the stimulated compared with the control leg (0.0344 ± 0.0019 vs. 0.0297 ± 0.0016 MPE, respectively; P protein-derived amino acids in the NMES compared with CON leg. In conclusion, application of NMES prior to presleep protein feeding stimulates the use of dietary protein-derived amino acids for overnight muscle protein synthesis in older men. Neuromuscular electrical stimulation (NMES) as well as presleep dietary protein ingestion represent effective strategies to stimulate muscle protein synthesis rates. Here we demonstrate that in older men after a day of bed rest, the application of NMES prior to presleep protein feeding stimulates the use of

  1. Serratus muscle stimulation effectively treats notalgia paresthetica caused by long thoracic nerve dysfunction: a case series

    Directory of Open Access Journals (Sweden)

    Barad Meredith

    2009-09-01

    Full Text Available Abstract Currently, notalgia paresthetica (NP is a poorly-understood condition diagnosed on the basis of pruritus, pain, or both, in the area medial to the scapula and lateral to the thoracic spine. It has been proposed that NP is caused by degenerative changes to the T2-T6 vertebrae, genetic disposition, or nerve entrapment of the posterior rami of spinal nerves arising at T2-T6. Despite considerable research, the etiology of NP remains unclear, and a multitude of different treatment modalities have correspondingly met with varying degrees of success. Here we demonstrate that NP can be caused by long thoracic nerve injury leading to serratus anterior dysfunction, and that electrical muscle stimulation (EMS of the serratus anterior can successfully and conservatively treat NP. In four cases of NP with known injury to the long thoracic nerve we performed transcutaneous EMS to the serratus anterior in an area far lateral to the site of pain and pruritus, resulting in significant and rapid pain relief. These findings are the first to identify long thoracic nerve injury as a cause for notalgia paresthetica and electrical muscle stimulation of the serratus anterior as a possible treatment, and we discuss the implications of these findings on better diagnosing and treating notalgia paresthetica.

  2. Different stimulation frequencies alter synchronous fluctuations in motor evoked potential amplitude of intrinsic hand muscles – a TMS study.

    Directory of Open Access Journals (Sweden)

    Martin Victor Sale

    2016-03-01

    Full Text Available The amplitude of motor-evoked potentials (MEPs elicited with transcranial magnetic stimulation (TMS varies from trial-to-trial. Synchronous oscillations in cortical neuronal excitability contribute to this variability, however it is not known how different frequencies of stimulation influence MEP variability, and whether these oscillations are rhythmic or aperiodic. We stimulated the motor cortex with TMS at different regular (i.e., rhythmic rates, and compared this with pseudo-random (aperiodic timing. In 18 subjects, TMS was applied at three regular frequencies (0.05 Hz, 0.2 Hz, 1 Hz and one aperiodic frequency (mean 0.2 Hz. MEPs (n = 50 were recorded from three intrinsic hand muscles of the left hand with different functional and anatomical relations. MEP amplitude correlation was highest for the functionally related muscle pair, less for the anatomically related muscle pair and least for the functionally- and anatomically-unrelated muscle pair. MEP correlations were greatest with 1 Hz, and least for stimulation at 0.05 Hz. Corticospinal neuron synchrony is higher with shorter TMS intervals. Further, corticospinal neuron synchrony is similar irrespective of whether the stimulation is periodic or aperiodic. These findings suggest TMS frequency is a crucial consideration for studies using TMS to probe correlated activity between muscle pairs.

  3. 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.

  4. Immediate effect of selective neuromuscular electrical stimulation on the electromyographic activity of the vastus medialis oblique muscle

    Directory of Open Access Journals (Sweden)

    Denise DalAva Augusto

    2008-07-01

    Full Text Available http://dx.doi.org/10.5007/1980-0037.2008v10n2p155 The Patellofemoral pain syndrome (PFPS is described as an anterior or retropatellar knee pain in the absence of other associated diseases, and has often been associated with dysfunction of the vastus medialis oblique muscle (VMO. However, several studies have demonstrated the impossibility of selectively activating this muscle with exercises. The aim of the present study was to analyze the immediate effect of neuromuscular electrical stimulation of VMO muscle by means of monitoring the electromyographic activity of the vastus medialis oblique (VMO and vastus lateralis (VL muscles. Eighteen healthy women with a mean age of 23.2 years and mean BMI of 20 Kg/m2 were evaluated. The study protocol included electromyographic analysis of VMO and VL muscles, before and immediately after neuromuscular electrical stimulation of the VMO muscle. During the electromyographic analysis, the volunteers performed maximal voluntary isometric contraction in a 60° knee extension on an isokinetic dynamometer. “Russian current” apparatus was used for electrical stimulation. Results: The data analysis demonstrated a signifi cant increase in VMO activation intensity immediately after it had been electrically stimulated (p=0.0125, whereas VL activation intensity exhibited no signifi cant increase (p=0.924. Moreover, a significant increase in the VMO/VL ratio was also detected (p=0.048. In this study it was observed that electrical stimulation modifiedthe VMO/VL ratio, which suggests electrical stimulation has a benefi cial effect on VMO muscle strength.

  5. Effects of Neuromuscular Electrical Stimulation During Hemodialysis on Peripheral Muscle Strength and Exercise Capacity: A Randomized Clinical Trial.

    Science.gov (United States)

    Brüggemann, Ana Karla; Mello, Carolina Luana; Dal Pont, Tarcila; Hizume Kunzler, Deborah; Martins, Daniel Fernandes; Bobinski, Franciane; Pereira Yamaguti, Wellington; Paulin, Elaine

    2017-05-01

    To evaluate the effects of neuromuscular electrical stimulation of high and low frequency and intensity, performed during hemodialysis, on physical function and inflammation markers in patients with chronic kidney disease (CKD). Randomized clinical trial. Hemodialysis clinic. Patients with CKD (N=51) were randomized into blocks of 4 using opaque sealed envelopes. They were divided into a group of high frequency and intensity neuromuscular electrical stimulation and a group of low frequency and intensity neuromuscular electrical stimulation. The high frequency and intensity neuromuscular electrical stimulation group was submitted to neuromuscular electrical stimulation at a frequency of 50Hz and a medium intensity of 72.90mA, and the low frequency and intensity neuromuscular electrical stimulation group used a frequency of 5Hz and a medium intensity of 13.85mA, 3 times per week for 1 hour, during 12 sessions. Peripheral muscle strength, exercise capacity, levels of muscle trophism marker (insulin growth factor 1) and levels of proinflammatory (tumor necrosis factor α) and anti-inflammatory (interleukin 10) cytokines. The high frequency and intensity neuromuscular electrical stimulation group showed a significant increase in right peripheral muscle strength (155.35±65.32Nm initial vs 161.60±68.73Nm final; P=.01) and left peripheral muscle strength (156.60±66.51Nm initial vs 164.10±69.76Nm final; P=.02) after the training, which did not occur in the low frequency and intensity neuromuscular electrical stimulation group for both right muscle strength (109.40±32.08Nm initial vs 112.65±38.44Nm final; P=.50) and left muscle strength (113.65±37.79Nm initial vs 116.15±43.01Nm final; P=.61). The 6-minute walk test distance (6MWTD) increased in both groups: high frequency and intensity neuromuscular electrical stimulation group (435.55±95.81m initial vs 457.25±90.64m final; P=.02) and low frequency and intensity neuromuscular electrical stimulation group (403.80

  6. Investigation of the Relationship Between Electrical Stimulation Frequency and Muscle Frequency Response Under Submaximal Contractions.

    Science.gov (United States)

    Papcke, Caluê; Krueger, Eddy; Olandoski, Marcia; Nogueira-Neto, Guilherme Nunes; Nohama, Percy; Scheeren, Eduardo Mendonça

    2018-03-25

    Neuromuscular electrical stimulation (NMES) is a common tool that is used in clinical and laboratory experiments and can be combined with mechanomyography (MMG) for biofeedback in neuroprostheses. However, it is not clear if the electrical current applied to neuromuscular tissues influences the MMG signal in submaximal contractions. The objective of this study is to investigate whether the electrical stimulation frequency influences the mechanomyographic frequency response of the rectus femoris muscle during submaximal contractions. Thirteen male participants performed three maximal voluntary isometric contractions (MVIC) recorded in isometric conditions to determine the maximal force of knee extensors. This was followed by the application of nine modulated NMES frequencies (20, 25, 30, 35, 40, 45, 50, 75, and 100 Hz) to evoke 5% MVIC. Muscle behavior was monitored by the analysis of MMG signals, which were decomposed into frequency bands by using a Cauchy wavelet transform. For each applied electrical stimulus frequency, the mean MMG spectral/frequency response was estimated for each axis (X, Y, and Z axes) of the MMG sensor with the values of the frequency bands used as weights (weighted mean). Only with respect to the Z (perpendicular) axis of the MMG signal, the stimulus frequency of 20 Hz did not exhibit any difference with the weighted mean (P = 0.666). For the frequencies of 20 and 25 Hz, the MMG signal displayed the bands between 12 and 16 Hz in the three axes (P frequencies from 30 to 100 Hz, the muscle presented a higher concentration of the MMG signal between the 22 and 29 Hz bands for the X and Z axes, and between 16 and 34 Hz bands for the Y axis (P frequency, because their frequency contents tend to mainly remain between the 20- and 25-Hz bands. Hence, NMES does not interfere with the use of MMG in neuroprosthesis. © 2018 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  7. Acupuncture plus Low-Frequency Electrical Stimulation (Acu-LFES Attenuates Diabetic Myopathy by Enhancing Muscle Regeneration.

    Directory of Open Access Journals (Sweden)

    Zhen Su

    Full Text Available Mortality and morbidity are increased in patients with muscle atrophy resulting from catabolic diseases such as diabetes. At present there is no pharmacological treatment that successfully reverses muscle wasting from catabolic conditions. We hypothesized that acupuncture plus low frequency electric stimulation (Acu-LFES would mimic the impact of exercise and prevent diabetes-induced muscle loss. Streptozotocin (STZ was used to induce diabetes in mice. The mice were then treated with Acu-LFES for 15 minutes daily for 14 days. Acupuncture points were selected according to the WHO Standard Acupuncture Nomenclature guide. The needles were connected to an SDZ-II electronic acupuncture device delivering pulses at 20Hz and 1mA. Acu-LFES prevented soleus and EDL muscle weight loss and increased hind-limb muscle grip function in diabetic mice. Muscle regeneration capacity was significantly increased by Acu-LFES. The expression of Pax7, MyoD, myogenin and embryo myosin heavy chain (eMyHC was significantly decreased in diabetic muscle vs. control muscle. The suppressed levels in diabetic muscle were reversed by Acu-LFES. The IGF-1 signaling pathway was also upregulated by Acu-LFES. Phosphorylation of Akt, mTOR and p70S6K were downregulated by diabetes leading to a decline in muscle mass, however, Acu-LFES countered the diabetes-induced decline. In addition, microRNA-1 and -206 were increased by Acu-LFES after 24 days of treatment. We conclude that Acu-LFES is effective in counteracting diabetes-induced skeletal muscle atrophy by increasing IGF-1 and its stimulation of muscle regeneration.

  8. The pH heterogeneity in human calf muscle during neuromuscular electrical stimulation.

    Science.gov (United States)

    Stutzig, Norman; Rzanny, Reinhard; Moll, Kevin; Gussew, Alexander; Reichenbach, Jürgen R; Siebert, Tobias

    2017-06-01

    The aim of the study was to examine pH heterogeneity during fatigue induced by neuromuscular electrical stimulation (NMES) using phosphorus magnetic resonance spectroscopy ( 31 P-MRS). It is hypothesized that three pH components would occur in the 31 P-MRS during fatigue, representing three fiber types. The medial gastrocnemius of eight subjects was stimulated within a 3-Tesla whole body MRI scanner. The maximal force during stimulation (F stim ) was examined by a pressure sensor. Phosphocreatine (PCr), adenosintriphosphate, inorganic phosphate (Pi), and the corresponding pH were estimated by a nonvolume-selective 31 P-MRS using a small loop coil at rest and during fatigue. During fatigue, F stim and PCr decreased to 27% and 33% of their initial levels, respectively. In all cases, the Pi peak increased when NMES was started and split into three different peaks. Based on the single Pi peaks during fatigue, an alkaline (6.76 ± 0.08), a medium (6.40 ± 0.06), and an acidic (6.09 ± 0.05) pH component were observed compared to the pH (7.02 ± 0.02) at rest. It is suggested that NMES is able to induce pH heterogeneity in the medial gastrocnemius, and that the single Pi peaks represent the different muscle fiber types of the skeletal muscle. Magn Reson Med 77:2097-2106, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  9. Neuromuscular electrical stimulation of the cricothyroid muscle in patients with suspected superior laryngeal nerve weakness.

    Science.gov (United States)

    Guzman, Marco; Rubin, Adam; Cox, Paul; Landini, Fernando; Jackson-Menaldi, Cristina

    2014-03-01

    In this retrospective case study, we report the apparent clinical effectiveness of neuromuscular electrical stimulation (NMES) in combination with voice therapy (VT) for rehabilitating dysphonia secondary to suspected superior laryngeal nerve (SLN) weakness in two female patients. Both patients failed or plateaued with traditional VT but had significant improvement with the addition of NMES of the cricothyroid muscle and SLN using a VitalStim unit. Stimulation was provided simultaneously with voice exercises based on musical phonatory tasks. Both acoustic analysis and endoscopic evaluation demonstrated important improvements after treatment. In the first patient, the major change was obtained within the primo passaggio region; specifically, a decrease in voice breaks was demonstrated. In the second patient, an improvement in voice quality (less breathiness) and vocal range were the most important findings. Additionally, each patient reported a significant improvement in their voice complaints. Neuromuscular laryngeal electrical stimulation in combination with vocal exercises might be a useful tool to improve voice quality in patients with SLN injury. Copyright © 2014 The Voice Foundation. Published by Mosby, Inc. All rights reserved.

  10. Electrical Stimulation of Artificial Heart Muscle: a look into the electrophysiological and genetic implications

    Science.gov (United States)

    Mohamed, Mohamed A; Islas, Jose F; Schwartz, Robert J; Birla, Ravi K

    2016-01-01

    Development of tissue-engineered hearts for treatment of myocardial infarction or biological pacemakers has been hindered by the production of mostly arrhythmic or in-synergistic constructs. Electrical stimulation (ES) of these constructs has been shown to produce tissues with greater twitch force and better adrenergic response. In order to further our understanding of the mechanisms underlying the effect of ES, we fabricated a bioreactor capable of delivering continuous or intermittent waveforms of various types to multiple constructs simultaneously. In this study, we examined the effect of an intermittent biphasic square wave on our artificial heart muscle (AHM) composed of neonatal rat cardiac cells and fibrin gel. Twitch forces, spontaneous contraction rates, biopotentials, gene expression profiles, and histological observations were examined for the ES protocol over a 12 day culture period. We demonstrate improved consistency between samples for twitch force and contraction rate, and higher normalized twitch force amplitudes for electrically stimulated AHM. Improvements in electrophysiology within the AHM was noted by higher conduction velocities and lower latency in electrical response for electrically stimulated AHM. Genes expressing key electrophysiological and structural markers peaked at days 6 and 8 of culture, only a few days after the initiation of ES. These results may be used for optimization strategies to establish protocols for producing AHM capable of replacing damaged heart tissue in either a contractile or electrophysiological capacity. Optimized AHM can lead to alternative treatments to heart failure and alleviate the limited donor supply crisis. PMID:28459744

  11. Electrical Stimulation of Artificial Heart Muscle: A Look Into the Electrophysiologic and Genetic Implications.

    Science.gov (United States)

    Mohamed, Mohamed A; Islas, Jose F; Schwartz, Robert J; Birla, Ravi K

    Development of tissue-engineered hearts for treatment of myocardial infarction or biologic pacemakers has been hindered by the production of mostly arrhythmic or in-synergistic constructs. Electrical stimulation (ES) of these constructs has been shown to produce tissues with greater twitch force and better adrenergic response. To further our understanding of the mechanisms underlying the effect of ES, we fabricated a bioreactor capable of delivering continuous or intermittent waveforms of various types to multiple constructs simultaneously. In this study, we examined the effect of an intermittent biphasic square wave on our artificial heart muscle (AHM) composed of neonatal rat cardiac cells and fibrin gel. Twitch forces, spontaneous contraction rates, biopotentials, gene expression profiles, and histologic observations were examined for the ES protocol over a 12 day culture period. We demonstrate improved consistency between samples for twitch force and contraction rate, and higher normalized twitch force amplitudes for electrically stimulated AHMs. Improvements in electrophysiology within the AHM were noted by higher conduction velocities and lower latency in electrical response for electrically stimulated AHMs. Genes expressing key electrophysiologic and structural markers peaked at days 6 and 8 of culture, only a few days after the initiation of ES. These results may be used for optimization strategies to establish protocols for producing AHMs capable of replacing damaged heart tissue in either a contractile or electrophysiologic capacity. Optimized AHMs can lead to alternative treatments to heart failure and alleviate the limited donor supply crisis.

  12. Evoked EMG versus Muscle Torque during Fatiguing Functional Electrical Stimulation-Evoked Muscle Contractions and Short-Term Recovery in Individuals with Spinal Cord Injury

    Science.gov (United States)

    Estigoni, Eduardo H.; Fornusek, Che; Hamzaid, Nur Azah; Hasnan, Nazirah; Smith, Richard M.; Davis, Glen M.

    2014-01-01

    This study investigated whether the relationship between muscle torque and m-waves remained constant after short recovery periods, between repeated intervals of isometric muscle contractions induced by functional electrical stimulation (FES). Eight subjects with spinal cord injury (SCI) were recruited for the study. All subjects had their quadriceps muscles group stimulated during three sessions of isometric contractions separated by 5 min of recovery. The evoked-electromyographic (eEMG) signals, as well as the produced torque, were synchronously acquired during the contractions and during short FES bursts applied during the recovery intervals. All analysed m-wave variables changed progressively throughout the three contractions, even though the same muscle torque was generated. The peak to peak amplitude (PtpA), and the m-wave area (Area) were significantly increased, while the time between the stimulus artefact and the positive peak (PosT) were substantially reduced when the muscles became fatigued. In addition, all m-wave variables recovered faster and to a greater extent than did torque after the recovery intervals. We concluded that rapid recovery intervals between FES-evoked exercise sessions can radically interfere in the use of m-waves as a proxy for torque estimation in individuals with SCI. This needs to be further investigated, in addition to seeking a better understanding of the mechanisms of muscle fatigue and recovery. PMID:25479324

  13. Effect of early implementation of electrical muscle stimulation to prevent muscle atrophy and weakness in patients after anterior cruciate ligament reconstruction.

    Science.gov (United States)

    Hasegawa, Satoshi; Kobayashi, Masahiko; Arai, Ryuzo; Tamaki, Akira; Nakamura, Takashi; Moritani, Toshio

    2011-08-01

    Following anterior cruciate ligament (ACL) reconstruction, restricted weight bearing and immobilization results in thigh and calf muscle atrophy and weakness. The purpose of this study was to assess the effect of electrical muscle stimulation (EMS) on prevention of muscle atrophy in patients during the early rehabilitation stage after ACL reconstruction. Twenty patients with acute ACL tears were divided into two groups randomly. The control group (CON group) participated in only the usual rehabilitation program. In addition to this protocol, the electrical muscle stimulation group (EMS group) received EMS training using the wave form of 20 Hz exponential pulse from the 2nd post-operative day to 4 weeks after the surgery. Muscle thickness of vastus lateralis and calf increased significantly 4 weeks after surgery in the EMS group, while it decreased significantly in the CON group. The decline of knee extension strength was significantly less in the EMS group than in the CON group at 4 weeks after the surgery, and the EMS group showed greater recovery of knee extension strength at 3 months after surgery. EMS implemented during the early rehabilitation stage is effective in maintaining and increasing muscle thickness and strength in the operated limb. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Amino acids augment muscle protein synthesis in neonatal pigs during acute endotoxemia by stimulating mTOR-dependent translation initiation.

    Science.gov (United States)

    Orellana, Renán A; Jeyapalan, Asumthia; Escobar, Jeffery; Frank, Jason W; Nguyen, Hanh V; Suryawan, Agus; Davis, Teresa A

    2007-11-01

    In skeletal muscle of adults, sepsis reduces protein synthesis by depressing translation initiation and induces resistance to branched-chain amino acid stimulation. Normal neonates maintain a high basal muscle protein synthesis rate that is sensitive to amino acid stimulation. In the present study, we determined the effect of amino acids on protein synthesis in skeletal muscle and other tissues in septic neonates. Overnight-fasted neonatal pigs were infused with endotoxin (LPS, 0 and 10 microg.kg(-1).h(-1)), whereas glucose and insulin were maintained at fasting levels; amino acids were clamped at fasting or fed levels. In the presence of fasting insulin and amino acids, LPS reduced protein synthesis in longissimus dorsi (LD) and gastrocnemius muscles and increased protein synthesis in the diaphragm, but had no effect in masseter and heart muscles. Increasing amino acids to fed levels accelerated muscle protein synthesis in LD, gastrocnemius, masseter, and diaphragm. LPS stimulated protein synthesis in liver, lung, spleen, pancreas, and kidney in fasted animals. Raising amino acids to fed levels increased protein synthesis in liver of controls, but not LPS-treated animals. The increase in muscle protein synthesis in response to amino acids was associated with increased mTOR, 4E-BP1, and S6K1 phosphorylation and eIF4G-eIF4E association in control and LPS-infused animals. These findings suggest that amino acids stimulate skeletal muscle protein synthesis during acute endotoxemia via mTOR-dependent ribosomal assembly despite reduced basal protein synthesis rates in neonatal pigs. However, provision of amino acids does not further enhance the LPS-induced increase in liver protein synthesis.

  15. A Biological Micro Actuator: Graded and Closed-Loop Control of Insect Leg Motion by Electrical Stimulation of Muscles

    OpenAIRE

    Cao, Feng; Zhang, Chao; Vo Doan, Tat Thang; Li, Yao; Sangi, Daniyal Haider; Koh, Jie Sheng; Huynh, Ngoc Anh; Aziz, Mohamed Fareez Bin; Choo, Hao Yu; Ikeda, Kazuo; Abbeel, Pieter; Maharbiz, Michel M.; Sato, Hirotaka

    2014-01-01

    In this study, a biological microactuator was demonstrated by closed-loop motion control of the front leg of an insect (Mecynorrhina torquata, beetle) via electrical stimulation of the leg muscles. The three antagonistic pairs of muscle groups in the front leg enabled the actuator to have three degrees of freedom: protraction/retraction, levation/depression, and extension/flexion. We observed that the threshold amplitude (voltage) required to elicit leg motions was approximately 1.0 V; thus, ...

  16. Rac1 governs exercise‐stimulated glucose uptake in skeletal muscle through regulation of GLUT4 translocation in mice

    Science.gov (United States)

    Nielsen, Ida L.; Kleinert, Maximilian; Møller, Lisbeth L. V.; Ploug, Thorkil; Schjerling, Peter; Bilan, Philip J.; Klip, Amira; Jensen, Thomas E.; Richter, Erik A.

    2016-01-01

    Key point Exercise increases skeletal muscle energy turnover and one of the important substrates for the working muscle is glucose taken up from the blood.The GTPase Rac1 can be activated by muscle contraction and has been found to be necessary for insulin‐stimulated glucose uptake, although its role in exercise‐stimulated glucose uptake is unknown.We show that Rac1 regulates the translocation of the glucose transporter GLUT4 to the plasma membrane in skeletal muscle during exercise.We find that Rac1 knockout mice display significantly reduced glucose uptake in skeletal muscle during exercise. Abstract Exercise increases skeletal muscle energy turnover and one of the important substrates for the working muscle is glucose taken up from the blood. Despite extensive efforts, the signalling mechanisms vital for glucose uptake during exercise are not yet fully understood, although the GTPase Rac1 is a candidate molecule. The present study investigated the role of Rac1 in muscle glucose uptake and substrate utilization during treadmill exercise in mice in vivo. Exercise‐induced uptake of radiolabelled 2‐deoxyglucose at 65% of maximum running capacity was blocked in soleus muscle and decreased by 80% and 60% in gastrocnemius and tibialis anterior muscles, respectively, in muscle‐specific inducible Rac1 knockout (mKO) mice compared to wild‐type littermates. By developing an assay to quantify endogenous GLUT4 translocation, we observed that GLUT4 content at the sarcolemma in response to exercise was reduced in Rac1 mKO muscle. Our findings implicate Rac1 as a regulatory element critical for controlling glucose uptake during exercise via regulation of GLUT4 translocation. PMID:27061726

  17. Group-level variations in motor representation areas of thenar and anterior tibial muscles: Navigated Transcranial Magnetic Stimulation Study.

    Science.gov (United States)

    Niskanen, Eini; Julkunen, Petro; Säisänen, Laura; Vanninen, Ritva; Karjalainen, Pasi; Könönen, Mervi

    2010-08-01

    Navigated transcranial magnetic stimulation (TMS) can be used to stimulate functional cortical areas at precise anatomical location to induce measurable responses. The stimulation has commonly been focused on anatomically predefined motor areas: TMS of that area elicits a measurable muscle response, the motor evoked potential. In clinical pathologies, however, the well-known homunculus somatotopy theory may not be straightforward, and the representation area of the muscle is not fixed. Traditionally, the anatomical locations of TMS stimulations have not been reported at the group level in standard space. This study describes a methodology for group-level analysis by investigating the normal representation areas of thenar and anterior tibial muscle in the primary motor cortex. The optimal representation area for these muscles was mapped in 59 healthy right-handed subjects using navigated TMS. The coordinates of the optimal stimulation sites were then normalized into standard space to determine the representation areas of these muscles at the group-level in healthy subjects. Furthermore, 95% confidence interval ellipsoids were fitted into the optimal stimulation site clusters to define the variation between subjects in optimal stimulation sites. The variation was found to be highest in the anteroposterior direction along the superior margin of the precentral gyrus. These results provide important normative information for clinical studies assessing changes in the functional cortical areas because of plasticity of the brain. Furthermore, it is proposed that the presented methodology to study TMS locations at the group level on standard space will be a suitable tool for research purposes in population studies. 2010 Wiley-Liss, Inc.

  18. Common neural structures activated by epidural and transcutaneous lumbar spinal cord stimulation: Elicitation of posterior root-muscle reflexes.

    Directory of Open Access Journals (Sweden)

    Ursula S Hofstoetter

    Full Text Available Epidural electrical stimulation of the lumbar spinal cord is currently regaining momentum as a neuromodulation intervention in spinal cord injury (SCI to modify dysregulated sensorimotor functions and augment residual motor capacity. There is ample evidence that it engages spinal circuits through the electrical stimulation of large-to-medium diameter afferent fibers within lumbar and upper sacral posterior roots. Recent pilot studies suggested that the surface electrode-based method of transcutaneous spinal cord stimulation (SCS may produce similar neuromodulatory effects as caused by epidural SCS. Neurophysiological and computer modeling studies proposed that this noninvasive technique stimulates posterior-root fibers as well, likely activating similar input structures to the spinal cord as epidural stimulation. Here, we add a yet missing piece of evidence substantiating this assumption. We conducted in-depth analyses and direct comparisons of the electromyographic (EMG characteristics of short-latency responses in multiple leg muscles to both stimulation techniques derived from ten individuals with SCI each. Post-activation depression of responses evoked by paired pulses applied either epidurally or transcutaneously confirmed the reflex nature of the responses. The muscle responses to both techniques had the same latencies, EMG peak-to-peak amplitudes, and waveforms, except for smaller responses with shorter onset latencies in the triceps surae muscle group and shorter offsets of the responses in the biceps femoris muscle during epidural stimulation. Responses obtained in three subjects tested with both methods at different time points had near-identical waveforms per muscle group as well as same onset latencies. The present results strongly corroborate the activation of common neural input structures to the lumbar spinal cord-predominantly primary afferent fibers within multiple posterior roots-by both techniques and add to unraveling the

  19. Partial fast-to-slow conversion of regenerating rat fast-twitch muscle by chronic low-frequency stimulation.

    Science.gov (United States)

    Pette, Dirk; Sketelj, Janez; Skorjanc, Dejan; Leisner, Elmi; Traub, Irmtrud; Bajrović, Fajko

    2002-01-01

    Chronic low-frequency stimulation (CLFS) of rat fast-twitch muscles induces sequential transitions in myosin heavy chain (MHC) expression from MHCIIb --> MHCIId/x --> MHCIIa. However, the 'final' step of the fast-to-slow transition, i.e., the upregulation of MHCI, has been observed only after extremely long stimulation periods. Assuming that fibre degeneration/regeneration might be involved in the upregulation of slow myosin, we investigated the effects of CLFS on extensor digitorum longus (EDL) muscles regenerating after bupivacaine-induced fibre necrosis. Normal, non-regenerating muscles responded to both 30- and 60-day CLFS with fast MHC isoform transitions (MHCIIb --> MHCIId --> MHCIIa) and only slight increases in MHCI. CLFS of regenerating EDL muscles caused similar transitions among the fast isoforms but, in addition, caused significant increases in MHCI (to approximately 30% relative concentration). Stimulation periods of 30 and 60 days induced similar changes in the regenerating bupivacaine-treated muscles, indicating that the upregulation of slow myosin was restricted to regenerating fibres, but only during an early stage of regeneration. These results suggest that satellite cells and/or regenerating fast rat muscle fibres are capable of switching directly to a slow program under the influence of CLFS and, therefore, appear to be more malleable than adult fibres.

  20. 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...

  1. Correlation of orbital muscle changes evaluated by magnetic resonance imaging and thyroid-stimulating antibody in patients with Graves' ophthalmopathy

    International Nuclear Information System (INIS)

    Nishikawa, M.; Yoshimura, M.; Inada, M.

    1993-01-01

    To evaluate the relationship between eye changes and autoantibody to the thyrotropin receptor in patients with Graves' disease, the authors evaluated the eye changes using magnetic resonance imaging and the results were correlated with thyroid-stimulating antibody, thyrotropin binding inhibitor immunoglobulin and thyroid growth activity. Subjects were 15 patients with Graves' disease who had Graves' ophthalmopathy, including exophthalmos and other signs and symptoms, and 9 patients without ophthalmopathy; all were maintained in a euthyroid state by antithyroid drugs. The thyrotropin-binding inhibitor imunoglobulin was measured by a kit, and thyroid-stimulating antibody and thyroid growth activity were evaluated by cyclic adenosine 3', 5'-monophosphate production and [ 3 H]thymidine incorporation, respectively, by cultured functional rat thyroid lined cells. The sum of the swelling ratios of the four extraocular muscles correlated well with the degree of exophthalmos. The thyrotropin-binding inhibitor immunoglobulin was positive in 9 out of 15 patients with ophthalmopathy; however, no correlation was observed between the activity and exophthalmos or muscle swelling. No significant correlation was observed between muscle changes and thyroid growth activity either. On the other hand, thyroid-stimulating antibody in Graves' patients with ophthalmopathy was significantly higher than that in patients without ophthalmopathy. Moreover, the level of the stimulating activity in Graves' patients with ophthalmopathy showed a significant positive correlation with the sum of the swelling ratios of the individual eight eye muscles. These results suggest that thyroid-stimulating antibody has a close relation to Graves' ophthalmopathy. 23 refs., 4 figs

  2. Production of inositol trisphosphates upon α-adrenergic stimulation in BC3H-1 muscle cells

    International Nuclear Information System (INIS)

    Ambler, S.K.; Thompson, B.; Brown, J.H.; Taylor, P.

    1986-01-01

    Activation of α 1 -adrenergic receptors in BC3H-1 muscle cells rapidly mobilizes intracellular and results in a paradoxically slower accumulation of inositol trisphosphate. A possible explanation for this discrepancy may be provided by the recent findings of Irvine et al. of additional Ins P3 isomers besides the Ca ++ -mobilizing isomer, Ins 1,4,5-P3. They have eluted and separated the inositol phosphates of BC3H-1 cells with an NH 4 + x HCO 2 - /H 3 PO 4 gradient on a Whatman Partisil 10SAX column using Hewlett-Packard HPLC. Commercial [ 3 H]Ins 1,4,5-P3 and [ 3 H]inositol phosphates from carbachol-stimulated parotid glands were used as standards. Little or no Ins 1,3,4-P3 could be detected in control or phenylephrine-treated BC3H-1 cells. Ins 1,4,5-P3 followed the pattern of agonist stimulation observed previously. As a positive control, Ins P3 isomers were also measured in 1321N1 astrocytoma cells. Muscarinic stimulation of 1321N1 cells results in both the rapid accumulation of Ins P3 and Ca ++ mobilization. There is no detectable basal Ins 1,3,4-P3, but carbachol stimulates a rapid production of this compound in 1321N1 cells. Agonist activation also results in a rapid increase in Ins 1,4,5-P3 above basal values. These studies indicate that Ins 1,3,4-P3 does not contribute to the InsP3 signal in BC3H-1 cells and multiple mechanisms may exist for the coupling of receptors to PI turnover

  3. Two weeks of metformin treatment induces AMPK dependent enhancement of insulin-stimulated glucose uptake in mouse soleus muscle

    DEFF Research Database (Denmark)

    Kristensen, Jonas Møller; Treebak, Jonas Thue; Schjerling, Peter

    2014-01-01

    signaling. Methods: Oral doses of metformin or saline treatment were given muscle-specific kinase α2 dead AMPK mice (KD) and wild type (WT) littermates either once or chronically for 2 weeks. Soleus and Extensor Digitorum Longus (EDL) muscles were used for measurements of glucose transport and Western blot......Background: Metformin-induced activation of AMPK has been associated with enhanced glucose uptake in skeletal muscle but so far no direct causality has been examined. We hypothesized that an effect of in vivo metformin treatment on glucose uptake in mouse skeletal muscles is dependent upon AMPK...... analyzes. Results: Chronic treatment with metformin enhanced insulin-stimulated glucose uptake in soleus muscles of WT (45%, P...

  4. Pelvic floor muscle exercises with or without electric stimulation and post-prostectomy urinary incontinence: a systematic review

    OpenAIRE

    Zaidan,Patrícia; Silva,Elirez Bezerra da

    2016-01-01

    Abstract Introduction: Urinary incontinence (UI) after prostatectomy is difficult to treat and causes profound adverse impacts on the individual's quality of life. The main clinical treatments available for post-prostatectomy UI consist of behavioral techniques and physical therapy techniques, such as exercises, electrical stimulation and biofeedback for pelvic floor muscles (PFMs). Objective: To investigate the effectiveness of PFM exercises with or without electrical stimulation for reduc...

  5. 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

  6. Presence and Absence of Muscle Contraction Elicited by Peripheral Nerve Electrical Stimulation Differentially Modulate Primary Motor Cortex Excitability

    Science.gov (United States)

    Sasaki, Ryoki; Kotan, Shinichi; Nakagawa, Masaki; Miyaguchi, Shota; Kojima, Sho; Saito, Kei; Inukai, Yasuto; Onishi, Hideaki

    2017-01-01

    Modulation of cortical excitability by sensory inputs is a critical component of sensorimotor integration. Sensory afferents, including muscle and joint afferents, to somatosensory cortex (S1) modulate primary motor cortex (M1) excitability, but the effects of muscle and joint afferents specifically activated by muscle contraction are unknown. We compared motor evoked potentials (MEPs) following median nerve stimulation (MNS) above and below the contraction threshold based on the persistence of M-waves. Peripheral nerve electrical stimulation (PES) conditions, including right MNS at the wrist at 110% motor threshold (MT; 110% MNS condition), right MNS at the index finger (sensory digit nerve stimulation [DNS]) with stimulus intensity approximately 110% MNS (DNS condition), and right MNS at the wrist at 90% MT (90% MNS condition) were applied. PES was administered in a 4 s ON and 6 s OFF cycle for 20 min at 30 Hz. In Experiment 1 (n = 15), MEPs were recorded from the right abductor pollicis brevis (APB) before (baseline) and after PES. In Experiment 2 (n = 15), M- and F-waves were recorded from the right APB. Stimulation at 110% MNS at the wrist evoking muscle contraction increased MEP amplitudes after PES compared with those at baseline, whereas DNS at the index finger and 90% MNS at the wrist not evoking muscle contraction decreased MEP amplitudes after PES. M- and F-waves, which reflect spinal cord or muscular and neuromuscular junctions, did not change following PES. These results suggest that muscle contraction and concomitant muscle/joint afferent inputs specifically enhance M1 excitability. PMID:28392766

  7. The response of denervated muscle to long-term stimulation (1985, revisited here in 2014

    Directory of Open Access Journals (Sweden)

    Terje Lomo

    2014-03-01

    Full Text Available In 1985, at a meeting in Abano, I presented results showing that direct stimulation of skeletal muscles with appropriate stimulus patterns prevents the effects of denervation on non-junctional properties of muscle fibers. Hence, it appeared unnecessary to postulate that unknown nerve-derived trophic factors control such properties, as posited by the (anterograde neurotrophic hypothesis. Here I discuss this conclusion in the light of what we know today, particularly with respect to the many lines of evidence that were then taken to support the trophic hypothesis, but which today have alternative interpretations consistent with control by evoked impulse activity. Despite much effort, no one has yet identified any nerve-derived factor consistent with the neurotrophic hypothesis. Reports favoring the existence of neurotrophic factors were numerous before 2000. Now they have essentially disappeared from the literature, including original research papers, textbooks and handbooks, suggesting that the hypothesis is no longer arguable. Thus, the results that I presented in our paper in 1985 seem to have held up rather well.

  8. Effects of noxious stimulation to the back or calf muscles on gait stability.

    Science.gov (United States)

    van den Hoorn, Wolbert; Hug, François; Hodges, Paul W; Bruijn, Sjoerd M; van Dieën, Jaap H

    2015-11-26

    Gait stability is the ability to deal with small perturbations that naturally occur during walking. Changes in motor control caused by pain could affect this ability. This study investigated whether nociceptive stimulation (hypertonic saline injection) in a low back (LBP) or calf (CalfP) muscle affects gait stability. Sixteen participants walked on a treadmill at 0.94ms(-1) and 1.67ms(-1), while thorax kinematics were recorded using 3D-motion capture. From 110 strides, stability (local divergence exponent, LDE), stride-to-stride variability and root mean squares (RMS) of thorax linear velocities were calculated along the three movement axes. At 0.94ms(-1), independent of movement axes, gait stability was lower (higher LDE) and stride-to-stride variability was higher, during LBP and CalfP than no pain. This was more pronounced during CalfP, likely explained by the biomechanical function of calf muscles in gait, as supported by greater mediolateral RMS and stance time asymmetry than in LBP and no pain. At 1.67ms(-1), independent of movement axes, gait stability was greater and stride-to-stride variability was smaller with LBP than no pain and CalfP, whereas CalfP was not different from no pain. Opposite effects of LBP on gait stability between speeds suggests a more protective strategy at the faster speed. Although mediolateral RMS was greater and participants had more asymmetric stance times with CalfP than LBP and no pain, limited effect of CalfP at the faster speed could relate to greater kinematic constraints and smaller effects of calf muscle activity on propulsion at this speed. In conclusion, pain effects on gait stability depend on pain location and walking speed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. 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.

  10. {sup 99m}Tc-sestamibi muscle scintigraphy to assess the response to neuromuscular electrical stimulation of normal quadriceps femoris muscle

    Energy Technology Data Exchange (ETDEWEB)

    Pekindil, Y.; Sarikaya, A.; Birtane, M.; Pekindil, G.; Salan, A. [Trakya Univ., Edirne (Turkey). Hospital

    2001-08-01

    Neuromuscular electrical stimulation (NMES) is widely used for improving muscle strength by simultaneous contraction in the prevention of muscle atrophy. Although there exist many clinical methods for evaluating the therapeutic response of muscles, {sup 99m}Tc-sestamibi which is a skeletal muscle perfusion and metabolism agent has not previously been used for this purpose. The aim of our work was to ascertain whether {sup 99m}Tc-sestamibi muscle scintigraphy is useful in the monitoring of therapeutic response to NMES in healthy women. The study included 16 women aged between 21 and 45, with a mean age of 32.7{+-}6.4. Both quadriceps femoris muscles (QFM) of each patient were studied. After randomization to remove the effect of the dominant side, one QFM of each patient was subjected to the NMES procedure for a period of 20 days. NMES was performed with an alternating biphasic rectangular current, from a computed electrical stimulator daily for 23 minutes. After measurement of skinfold thickness over the thigh, pre- and post-NMES girth measurements were assessed in centimeters. Sixty minutes after injections of 555 MBq {sup 99m}Tc-sestamibi, static images of the thigh were obtained for 5 minutes. The thigh-to-knee uptake ratio was calculated by semiquantitative analysis and normalized to body surface area (NUR=normalized uptake ratio). The difference between the pre and post NMES NUR values was significant (1.76{+-}0.31 versus 2.25{+-}0.38, p=0.0000). The percentage (%) increase in NUR values also well correlated with the % increase in thigh girth measurements (r=0.89, p=0.0000). These results indicated that {sup 99m}Tc-sestamibi muscle scintigraphy as a new tool may be useful in evaluating therapeutic response to NMES. (author)

  11. Peripheral nerve stimulation (PNS) in the trapezius muscle region alleviate chronic neuropathic pain after lower brachial plexus root avulsion lesion: A case report

    DEFF Research Database (Denmark)

    Sørensen, Jens Christian Hedemann; Meier, Kaare; Perinpam, Larshan

    Peripheral nerve stimulation (PNS) in the trapezius muscle region alleviate chronic neuropathic pain after lower brachial plexus root avulsion lesion: A case report......Peripheral nerve stimulation (PNS) in the trapezius muscle region alleviate chronic neuropathic pain after lower brachial plexus root avulsion lesion: A case report...

  12. 3D Modelling and monitoring of denervated muscle under Functional Electrical Stimulation treatment and associated bone structural changes

    Directory of Open Access Journals (Sweden)

    Paolo Gargiulo

    2011-03-01

    Full Text Available A novel clinical rehabilitation method for patients who have permanent and non recoverable muscle denervation in the legs was developed in the frame of the European Project RISE. The technique is based on FES and the project results shows, in these severely disabled patients, restoration of muscle tissue and function. This study propose novel methods based on image processing technique and medical modelling to monitor growth in denervated muscle treated with FES. Geometrical and structural changes in muscle and bone are studied and modelled. Secondary effects on the bone mineral density produced by the stimulation treatment and due the elicited muscle contraction are also investigated. The restoration process in DDM is an important object of discussion since there isn’t yet a complete understanding of the mechanisms regulating growth in denervated muscle. This study approaches the problem from a macroscopic point of view, developing 3-dimensional models of the whole stimulated muscles and following changes in volume, geometry and density very accurately. The method is based on the acquisition of high resolution Spiral CT scans from patients who have long-term flaccid paraplegia and the use of special image processing tools allowing tissue discriminations and muscle segmentation. Three patients were measured at different points of time during 4 years of electrical stimulation treatment. In this study is quantitatively demonstrated the influences of FES treatment on the different quadriceps bellies. The rectus femoris muscle is positioned in the middle of the quadriceps and responds (in general better to stimulation. In a patient with abundant adipose tissue surrounding the quadriceps, rectus femoris almost doubled the volume during the FES treatment while in the other bellies the changes measured were minimal. The analysis of the density shows clearly a restoration of the muscular structure in the growing muscle. The remarkable increase of

  13. Dietary obacunone supplementation stimulates muscle hypertrophy, and suppresses hyperglycemia and obesity through the TGR5 and PPARγ pathway

    Energy Technology Data Exchange (ETDEWEB)

    Horiba, Taro, E-mail: thoriba@mail.kikkoman.co.jp [Research and Development Division, Kikkoman Corporation, Chiba (Japan); Katsukawa, Masahiro [Research and Development Division, Kikkoman Corporation, Chiba (Japan); Mita, Moeko; Sato, Ryuichiro [Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Science, The University of Tokyo, Tokyo (Japan)

    2015-08-07

    Obacunone is a limonoid that is predominantly found in Citrus. Although various biological activities of limonoids have been reported, little is known about the beneficial effects of obacunone on metabolic disorders. In the present study, we examined the effects of dietary obacunone supplementation on obese KKAy mice, to clarify the function of obacunone in metabolic regulation. Mice were pair-fed a normal diet either alone or supplemented with 0.1% w/w obacunone for 28 days. Compared with the control, obacunone-fed mice had lower glycosylated hemoglobin, blood glucose, and white adipose tissue weight, although there was no significant difference in body weight. Obacunone treatment also significantly increased the weight of the gastrocnemius and quadriceps muscles. Reporter gene assays revealed that obacunone stimulated the transcriptional activity of the bile acids-specific G protein-coupled receptor, TGR5, in a dose-dependent manner. In addition, obacunone inhibited adipocyte differentiation in 3T3-L1 cells and antagonized ligand-stimulated peroxisome proliferator-activated receptor γ (PPARγ) transcriptional activity. These results suggest that obacunone stimulates muscle hypertrophy and prevents obesity and hyperglycemia, and that these beneficial effects are likely to be mediated through the activation of TGR5 and inhibition of PPARγ transcriptional activity. - Highlights: • Citrus limonoid obacunone prevents hyperglycemia in obese, diabetic KKAy mice. • Obacunone reduces fat content and stimulates muscle hypertrophy in KKAy mice. • Obacunone stimulates TGR5 transcriptional activities. • Obacunone antagonizes PPARγ and inhibits lipid accumulation in adipocytes.

  14. Dietary obacunone supplementation stimulates muscle hypertrophy, and suppresses hyperglycemia and obesity through the TGR5 and PPARγ pathway

    International Nuclear Information System (INIS)

    Horiba, Taro; Katsukawa, Masahiro; Mita, Moeko; Sato, Ryuichiro

    2015-01-01

    Obacunone is a limonoid that is predominantly found in Citrus. Although various biological activities of limonoids have been reported, little is known about the beneficial effects of obacunone on metabolic disorders. In the present study, we examined the effects of dietary obacunone supplementation on obese KKAy mice, to clarify the function of obacunone in metabolic regulation. Mice were pair-fed a normal diet either alone or supplemented with 0.1% w/w obacunone for 28 days. Compared with the control, obacunone-fed mice had lower glycosylated hemoglobin, blood glucose, and white adipose tissue weight, although there was no significant difference in body weight. Obacunone treatment also significantly increased the weight of the gastrocnemius and quadriceps muscles. Reporter gene assays revealed that obacunone stimulated the transcriptional activity of the bile acids-specific G protein-coupled receptor, TGR5, in a dose-dependent manner. In addition, obacunone inhibited adipocyte differentiation in 3T3-L1 cells and antagonized ligand-stimulated peroxisome proliferator-activated receptor γ (PPARγ) transcriptional activity. These results suggest that obacunone stimulates muscle hypertrophy and prevents obesity and hyperglycemia, and that these beneficial effects are likely to be mediated through the activation of TGR5 and inhibition of PPARγ transcriptional activity. - Highlights: • Citrus limonoid obacunone prevents hyperglycemia in obese, diabetic KKAy mice. • Obacunone reduces fat content and stimulates muscle hypertrophy in KKAy mice. • Obacunone stimulates TGR5 transcriptional activities. • Obacunone antagonizes PPARγ and inhibits lipid accumulation in adipocytes

  15. The pathway to muscle fibrosis depends on myostatin stimulating the differentiation of fibro/adipogenic progenitor cells in chronic kidney disease.

    Science.gov (United States)

    Dong, Jiangling; Dong, Yanjun; Chen, Zihong; Mitch, William E; Zhang, Liping

    2017-01-01

    Fibrosis in skeletal muscle develops after injury or in response to chronic kidney disease (CKD), but the origin of cells becoming fibrous tissue and the initiating and sustaining mechanisms causing muscle fibrosis are unclear. We identified muscle fibro/adipogenic progenitor cells (FAPs) that potentially differentiate into adipose tissues or fibrosis. We also demonstrated that CKD stimulates myostatin production in muscle. Therefore, we tested whether CKD induces myostatin, which stimulates fibrotic differentiation of FAPs leading to fibrosis in skeletal muscles. We isolated FAPs from mouse muscles and found that myostatin stimulates their proliferation and conversion into fibrocytes. In vivo, FAPs isolated from EGFP-transgenic mice (FAPs-EGFP) were transplanted into muscles of mice with CKD or into mouse muscles that were treated with myostatin. CKD or myostatin stimulated FAPs-EGFP proliferation in muscle and increased α-smooth muscle actin expression in FAP-EGFP cells. When myostatin was inhibited with a neutralizing peptibody (a chimeric peptide-Fc fusion protein), the FAP proliferation and muscle fibrosis induced by CKD were both suppressed. Knocking down Smad3 in cultured FAPs interrupted their conversion into fibrocytes, indicating that myostatin directly converts FAPs into fibrocytes. Thus, counteracting myostatin may be a strategy for preventing the development of fibrosis in skeletal muscles of patients with CKD. Copyright © 2016 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

  16. Skeletal muscle PLIN3 and PLIN5 are serine phosphorylated at rest and following lipolysis during adrenergic or contractile stimulation

    Science.gov (United States)

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

    2013-01-01

    In adipose tissue, access of adipose triglyceride and hormone-sensitive lipases (ATGL and HSL) to the lipid droplet depends on PLIN1 phosphorylation, however, PLIN1 is not expressed in skeletal muscle and the phosphorylation of the expressed PLINs has yet to be investigated. Further, direct interactions between skeletal muscle PLINs and HSL are unknown. We investigated the isolated and combined effects of epinephrine and contraction on PLIN-to-lipase interactions as well as phosphorylation. Isolated rat solei were assigned to one of four 30 min in vitro conditions (25°C): (1) rest; (2) intermittent tetanic stimulation (60 Hz for 150 msec; train rate 20/min); (3) 5 nmol/L epinephrine; (4) intermittent tetanic stimulation and 5 nmol/L epinephrine. Immunoprecipitation of serine phosphorylated proteins followed by Western blotting for PLIN2, PLIN3, PLIN5, revealed that only PLIN2 is not phosphorylated under any of the experimental conditions. This is the first study to show that in whole rat skeletal muscle PLIN3 and PLIN5 are serine phosphorylated. The degree of serine phosphorylation remained unchanged following adrenergic and/or contractile stimulation. Oil red O staining of muscle sections for lipid content shows a significant decrease following each condition, confirming lipolysis occurred (P < 0.05). PLIN2, 3, and 5 all interact with HSL and ATGL, but these interactions were unchanged following treatments. Our results show that in skeletal muscle, PLIN2 is not serine phosphorylated at rest or with lipolytic stimulation and that while PLIN3, PLIN5 are serine phosphorylated at rest, the degree of phosphorylation does not change with lipolytic stimulation. PMID:24303154

  17. Pressure pain threshold changes after repeated mechano-nociceptive stimulation of the trapezius muscle: possible influence of previous pain experience

    DEFF Research Database (Denmark)

    Sjölund, Bengt H; Persson, Ann L

    2007-01-01

    or an increase. Normalized data, transformed into mean unidirectional PPT differences, showed statistically highly significant changes after intervention. The relative risk of reacting with lowered PPTs on noxious stimulation was 3.7 times higher for subjects who had not given birth to children than for subjects...... over 1 trapezius muscle (skin anaesthetized) in 27 healthy women before and after the intervention. With a mean stimulation rate of 0.40 Hz and a mean nociceptive stimulation intensity of 1.78 x Threshold, subjects were found to systematically react with a change in PPT, either a decrease...... who had given birth to 1 or several children (Pstimulation of the trapezius muscle in healthy females evokes moderate and temporary...

  18. Growth hormone stimulates the collagen synthesis in human tendon and skeletal muscle without affecting myofibrillar protein synthesis

    DEFF Research Database (Denmark)

    Doessing, Simon; Heinemeier, Katja M; Holm, Lars

    2010-01-01

    young individuals. rhGH administration caused an increase in serum GH, serum IGF-I, and IGF-I mRNA expression in tendon and muscle. Tendon collagen I mRNA expression and tendon collagen protein synthesis increased by 3.9-fold and 1.3-fold, respectively (P ...RNA expression and muscle collagen protein synthesis increased by 2.3-fold and 5.8-fold, respectively (P protein synthesis was unaffected by elevation of GH and IGF-I. Moderate exercise did not enhance the effects of GH manipulation. Thus, increased GH availability stimulates...... matrix collagen synthesis in skeletal muscle and tendon, but without any effect upon myofibrillar protein synthesis. The results suggest that GH is more important in strengthening the matrix tissue than for muscle cell hypertrophy in adult human musculotendinous tissue....

  19. FIRST SOUND EVIDENCE OF MUSCLE REGENERATION IN RECOVERY OF FUNCTION OF HUMAN PERMANENT DENERVATED MUSCLES BY A LONG-LASTING FUNCTIONAL ELECTRICAL STIMULATION (FES TRAINING: BIOPSY FINDINGS

    Directory of Open Access Journals (Sweden)

    Helmut Kern

    2004-12-01

    Full Text Available Contrary to general believe, in one case of 18month cauda equina lesion four-month electrical stimulation of thigh muscles (impulse energy 1.92 Joule increased stimulation frequency from 2 to 20 Hz, i. e., up to tetanic contractions. After 2 years of treatment, CT-cross sectional area of quadriceps improved 58.3% (right and 44.4% (left with increased muscle density. Mean myofiber size was 37.2 ± 24.8 µm (right and 40.5 ±  24.9 µm (left. Improvement of stimulated knee torque, from zero to 12.0 Nm and 10.5 Nm, respectively, enabled to stand up trials. Surviving myofibers undergo re-growth (they show the chess board appearance of normal muscle, and dying myofibers continuously regenerate (up to 3% are embryonic myosin positive 3-year post-FES. Regeneration events are essential components of the FES rehabilitation protocol due to superior excitability of regenerated myofibers in comparison to long-term denervated, degenerated myofibers, which were almost not excitable before FES training.

  20. Branched-Chain Amino Acid Ingestion Stimulates Muscle Myofibrillar Protein Synthesis following Resistance Exercise in Humans

    Directory of Open Access Journals (Sweden)

    Sarah R. Jackman

    2017-06-01

    Full Text Available The ingestion of intact protein or essential amino acids (EAA stimulates mechanistic target of rapamycin complex-1 (mTORC1 signaling and muscle protein synthesis (MPS following resistance exercise. The purpose of this study was to investigate the response of myofibrillar-MPS to ingestion of branched-chain amino acids (BCAAs only (i.e., without concurrent ingestion of other EAA, intact protein, or other macronutrients following resistance exercise in humans. Ten young (20.1 ± 1.3 years, resistance-trained men completed two trials, ingesting either 5.6 g BCAA or a placebo (PLA drink immediately after resistance exercise. Myofibrillar-MPS was measured during exercise recovery with a primed, constant infusion of L-[ring13C6] phenylalanine and collection of muscle biopsies pre and 4 h-post drink ingestion. Blood samples were collected at time-points before and after drink ingestion. Western blotting was used to measure the phosphorylation status of mTORC1 signaling proteins in biopsies collected pre, 1-, and 4 h-post drink. The percentage increase from baseline in plasma leucine (300 ± 96%, isoleucine (300 ± 88%, and valine (144 ± 59% concentrations peaked 0.5 h-post drink in BCAA. A greater phosphorylation status of S6K1Thr389 (P = 0.017 and PRAS40 (P = 0.037 was observed in BCAA than PLA at 1 h-post drink ingestion. Myofibrillar-MPS was 22% higher (P = 0.012 in BCAA (0.110 ± 0.009%/h than PLA (0.090 ± 0.006%/h. Phenylalanine Ra was ~6% lower in BCAA (18.00 ± 4.31 μmol·kgBM−1 than PLA (21.75 ± 4.89 μmol·kgBM−1; P = 0.028 after drink ingestion. We conclude that ingesting BCAAs alone increases the post-exercise stimulation of myofibrillar-MPS and phosphorylation status mTORC1 signaling.

  1. Two weeks of metformin treatment induces AMPK-dependent enhancement of insulin-stimulated glucose uptake in mouse soleus muscle

    Science.gov (United States)

    Kristensen, Jonas Møller; Treebak, Jonas T.; Schjerling, Peter; Goodyear, Laurie

    2014-01-01

    Metformin-induced activation of the 5′-AMP-activated protein kinase (AMPK) has been associated with enhanced glucose uptake in skeletal muscle, but so far no direct causality has been examined. We hypothesized that an effect of in vivo metformin treatment on glucose uptake in mouse skeletal muscles is dependent on AMPK signaling. Oral doses of metformin or saline treatment were given to muscle-specific kinase dead (KD) AMPKα2 mice and wild-type (WT) littermates either once or chronically for 2 wk. Soleus and extensor digitorum longus muscles were used for measurements of glucose transport and Western blot analyses. Chronic treatment with metformin enhanced insulin-stimulated glucose uptake in soleus muscles of WT (∼45%, P metformin treatment. Insulin signaling at the level of Akt and TBC1D4 protein expression as well as Akt Thr308/Ser473 and TBC1D4 Thr642/Ser711 phosphorylation were not changed by metformin treatment. Also, protein expressions of Rab4, GLUT4, and hexokinase II were unaltered after treatment. The acute metformin treatment did not affect glucose uptake in muscle of either of the genotypes. In conclusion, we provide novel evidence for a role of AMPK in potentiating the effect of insulin on glucose uptake in soleus muscle in response to chronic metformin treatment. PMID:24644243

  2. Effect of tendon vibration during wide-pulse neuromuscular electrical stimulation (NMES) on the decline and recovery of muscle force.

    Science.gov (United States)

    Bochkezanian, Vanesa; Newton, Robert U; Trajano, Gabriel S; Vieira, Amilton; Pulverenti, Timothy S; Blazevich, Anthony J

    2017-05-02

    Neuromuscular electrical stimulation (NMES) is commonly used to activate skeletal muscles and reverse muscle atrophy in clinical populations. Clinical recommendations for NMES suggest the use of short pulse widths (100-200 μs) and low-to-moderate pulse frequencies (30-50 Hz). However, this type of NMES causes rapid muscle fatigue due to the (non-physiological) high stimulation intensities and non-orderly recruitment of motor units. The use of both wide pulse widths (1000 μs) and tendon vibration might optimize motor unit activation through spinal reflex pathways and thus delay the onset of muscle fatigue, increasing muscle force and mass. Thus, the objective of this study was to examine the acute effects of patellar tendon vibration superimposed onto wide-pulse width (1000 μs) knee extensor electrical stimulation (NMES, 30 Hz) on peak muscle force, total impulse before "muscle fatigue", and the post-exercise recovery of muscle function. Tendon vibration (Vib), NMES (STIM) or NMES superimposed onto vibration (STIM + Vib) were applied in separate sessions to 16 healthy adults. Total torque-time integral (TTI), maximal voluntary contraction torque (MVIC) and indirect measures of muscle damage were tested before, immediately after, 1 h and 48 h after each stimulus. TTI increased (145.0 ± 127.7%) in STIM only for "positive responders" to the tendon vibration (8/16 subjects), but decreased in "negative responders" (-43.5 ± 25.7%). MVIC (-8.7%) and rectus femoris electromyography (RF EMG) (-16.7%) decreased after STIM (group effect) for at least 1 h, but not after STIM + Vib. No changes were detected in indirect markers of muscle damage in any condition. Tendon vibration superimposed onto wide-pulse width NMES increased TTI only in 8 of 16 subjects, but reduced voluntary force loss (fatigue) ubiquitously. Negative responders to tendon vibration may derive greater benefit from wide-pulse width NMES alone.

  3. K+-induced alterations in airway muscle responsiveness to electrical field stimulation

    International Nuclear Information System (INIS)

    Murlas, C.; Ehring, G.; Suszkiw, J.; Sperelakis, N.

    1986-01-01

    We investigated possible pre- and postsynaptic effects of K+-induced depolarization on ferret tracheal smooth muscle (TSM) responsiveness to cholinergic stimulation. To assess electromechanical activity, cell membrane potential (Em) and tension (Tm) were simultaneously recorded in buffer containing 6, 12, 18, or 24 mM K+ before and after electrical field stimulation (EFS) or exogenous acetylcholine (ACh). In 6 mM K+, Em was -58.1 +/- 1.0 mV (mean +/- SE). In 12 mM K+, Em was depolarized to -52.3 +/- 0.9 mV, basal Tm did not change, and both excitatory junctional potentials and contractile responses to EFS at short stimulus duration were larger than in 6 mM K+. No such potentiation occurred at a higher K+, although resting Em and Tm increased progressively above 12 mM K+. The sensitivity of ferret TSM to exogenous ACh appeared unaffected by K+. To determine whether the hyperresponsiveness in 12 mM K+ was due, in part, to augmented ACh release from intramural airway nerves, experiments were done using TSM preparations incubated with [3H]choline to measure [3H]ACh release at rest and during EFS. Although resting [3H]ACh release increased progressively in higher K+, release evoked by EFS was maximal in 12 mM K+ and declined in higher concentrations. We conclude that small elevations in the extracellular K+ concentration augment responsiveness of the airways, by increasing the release of ACh both at rest and during EFS from intramural cholinergic nerve terminals. Larger increases in K+ appear to be inhibitory, possibly due to voltage-dependent effects that occur both pre- and postsynaptically

  4. 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.

  5. Local muscle metabolic demand induced by neuromuscular electrical stimulation and voluntary contractions at different force levels: a NIRS study

    Directory of Open Access Journals (Sweden)

    Makii Muthalib

    2016-06-01

    Full Text Available Functional Muscle metabolic demand during contractions evoked by neuromuscular electrical stimulation (NMES has been consistently documented to be greater than voluntary contractions (VOL at the same force level (10-50% maximal voluntary contraction-MVC. However, we have shown using a near-infrared spectroscopy (NIRS technique that local muscle metabolic demand is similar between NMES and VOL performed at MVC levels, thus controversy exists. This study therefore compared biceps brachii muscle metabolic demand (tissue oxygenation index-TOI and total hemoglobin volume-tHb during a 10s isometric contraction of the elbow flexors between NMES (stimulation frequency of 30Hz and current level to evoke 30% MVC and VOL at 30% MVC (VOL-30%MVC and MVC (VOL-MVC level in 8 healthy men (23-33-y. Greater changes in TOI and tHb induced by NMES than VOL-30%MVC confirm previous studies of a greater local metabolic demand for NMES than VOL at the same force level. The same TOI and tHb changes for NMES and VOL-MVC suggest that local muscle metabolic demand and intramuscular pressure were similar between conditions. In conclusion, these findings indicate that NMES induce a similar local muscle metabolic demand as that of maximal VOL.

  6. Local Muscle Metabolic Demand Induced by Neuromuscular Electrical Stimulation and Voluntary Contractions at Different Force Levels: A NIRS Study.

    Science.gov (United States)

    Muthalib, Makii; Kerr, Graham; Nosaka, Kazunori; Perrey, Stephane

    2016-06-13

    Functional Muscle metabolic demand during contractions evoked by neuromuscular electrical stimulation (NMES) has been consistently documented to be greater than voluntary contractions (VOL) at the same force level (10-50% maximal voluntary contraction-MVC). However, we have shown using a near-infrared spectroscopy (NIRS) technique that local muscle metabolic demand is similar between NMES and VOL performed at MVC levels, thus controversy exists. This study therefore compared biceps brachii muscle metabolic demand (tissue oxygenation index-TOI and total hemoglobin volume-tHb) during a 10s isometric contraction of the elbow flexors between NMES (stimulation frequency of 30Hz and current level to evoke 30% MVC) and VOL at 30% MVC (VOL-30%MVC) and MVC (VOL-MVC) level in 8 healthy men (23-33-y). Greater changes in TOI and tHb induced by NMES than VOL-30%MVC confirm previous studies of a greater local metabolic demand for NMES than VOL at the same force level. The same TOI and tHb changes for NMES and VOL-MVC suggest that local muscle metabolic demand and intramuscular pressure were similar between conditions. In conclusion, these findings indicate that NMES induce a similar local muscle metabolic demand as that of maximal VOL.

  7. Modulation of Muscle Tone and Sympathovagal Balance in Cervical Dystonia Using Percutaneous Stimulation of the Auricular Vagus Nerve.

    Science.gov (United States)

    Kampusch, Stefan; Kaniusas, Eugenijus; Széles, Jozsef C

    2015-10-01

    Primary cervical dystonia is characterized by abnormal, involuntary, and sustained contractions of cervical muscles. Current ways of treatment focus on alleviating symptomatic muscle activity. Besides pharmacological treatment, in severe cases patients may receive neuromodulative intervention such as deep brain stimulation. However, these (highly invasive) methods have some major drawbacks. For the first time, percutaneous auricular vagus nerve stimulation (pVNS) was applied in a single case of primary cervical dystonia. Auricular vagus nerve stimulation was already shown to modulate the (autonomous) sympathovagal balance of the body and proved to be an effective treatment in acute and chronic pain, epilepsy, as well as major depression. pVNS effects on cervical dystonia may be hypothesized to rely upon: (i) the alteration of sensory input to the brain, which affects structures involved in the genesis of motoric and nonmotoric dystonic symptoms; and (ii) the alteration of the sympathovagal balance with a sustained impact on involuntary movement control, pain, quality of sleep, and general well-being. The presented data provide experimental evidence that pVNS may be a new alternative and minimally invasive treatment in primary cervical dystonia. One female patient (age 50 years) suffering from therapy refractory cervical dystonia was treated with pVNS over 20 months. Significant improvement in muscle pain, dystonic symptoms, and autonomic regulation as well as a subjective improvement in motility, sleep, and mood were achieved. A subjective improvement in pain recorded by visual analog scale ratings (0-10) was observed from 5.42 to 3.92 (medians). Muscle tone of the mainly affected left and right trapezius muscle in supine position was favorably reduced by about 96%. Significant reduction of muscle tone was also achieved in sitting and standing positions of the patient. Habituation to stimulation leading to reduced stimulation efficiency was observed and

  8. 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...

  9. Toward the restoration of hand use to a paralyzed monkey: brain-controlled functional electrical stimulation of forearm muscles.

    Directory of Open Access Journals (Sweden)

    Eric A Pohlmeyer

    2009-06-01

    Full Text Available Loss of hand use is considered by many spinal cord injury survivors to be the most devastating consequence of their injury. Functional electrical stimulation (FES of forearm and hand muscles has been used to provide basic, voluntary hand grasp to hundreds of human patients. Current approaches typically grade pre-programmed patterns of muscle activation using simple control signals, such as those derived from residual movement or muscle activity. However, the use of such fixed stimulation patterns limits hand function to the few tasks programmed into the controller. In contrast, we are developing a system that uses neural signals recorded from a multi-electrode array implanted in the motor cortex; this system has the potential to provide independent control of multiple muscles over a broad range of functional tasks. Two monkeys were able to use this cortically controlled FES system to control the contraction of four forearm muscles despite temporary limb paralysis. The amount of wrist force the monkeys were able to produce in a one-dimensional force tracking task was significantly increased. Furthermore, the monkeys were able to control the magnitude and time course of the force with sufficient accuracy to track visually displayed force targets at speeds reduced by only one-third to one-half of normal. Although these results were achieved by controlling only four muscles, there is no fundamental reason why the same methods could not be scaled up to control a larger number of muscles. We believe these results provide an important proof of concept that brain-controlled FES prostheses could ultimately be of great benefit to paralyzed patients with injuries in the mid-cervical spinal cord.

  10. Palpebral portion of the orbicularis oculi muscle to repetitive nerve stimulation testing: A potential assessment indicator in patients with generalized myasthenia gravis.

    Science.gov (United States)

    Yan, Chong; Song, Jie; Pang, Song; Yi, Fangfang; Xi, Jianying; Zhou, Lei; Ding, Ding; Wang, Weifeng; Qiao, Kai; Zhao, Chongbo

    2018-02-01

    Repetitive nerve stimulation (RNS) is a valuable diagnostic method for myasthenia gravis (MG). However, its association with clinical severity was scarcely studied. We reviewed medical records and retrospectively enrolled 121 generalized MG patients. Sensitivity of different muscles to RNS and clinical scoring systems was evaluated. RNS testing revealed facial muscles have the highest positive rate, followed by proximal muscles and distal muscles, with the palpebral portion of the orbicularis oculi muscle most sensitive. Amplitude decrement of compound muscle action potential (CMAP) in the palpebral portion of the orbicularis oculi muscle is related to quantitative myasthenia gravis (QMG) scores, MG-specific manual muscle testing (MMT) scores and myasthenia gravis-related activities of daily living (MG-ADL) scores. We suggest that RNS testing of the palpebral portion of the orbicularis oculi muscle is a potential assessment indicator in patients with generalized MG. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Mechanisms underlying enhancements in muscle force and power output during maximal cycle ergometer exercise induced by chronic β2-adrenergic stimulation in men

    DEFF Research Database (Denmark)

    Hostrup, Morten; Kalsen, Anders; Onslev, Johan

    2015-01-01

    The study was a randomized placebo-controlled trial investigating mechanisms by which chronic β2-adrenergic stimulation enhances muscle force and power output during maximal cycle ergometer exercise in young men. Eighteen trained men were assigned to an experimental group (oral terbutaline 5 mg∙30...... of muscle proteins involved in growth, ion handling, lactate production and clearance increased (P≤0.05) with the intervention in TER compared to PLA, with no change in oxidative enzymes. Our observations suggest that muscle hypertrophy is the primary mechanism underlying enhancements in muscle force...... and peak power during maximal cycling induced by chronic β2-adrenergic stimulation in humans....

  12. 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...

  13. 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.

  14. Test–Retest Reliability and Concurrent Validity of an fMRI-Compatible Pneumatic Vibrator to Stimulate Muscle Proprioceptors.

    Science.gov (United States)

    Goossens, Nina; Janssens, Lotte; Pijnenburg, Madelon; Caeyenberghs, Karen; Van Rompuy, Charlotte; Meugens, Paul; Sunaert, Stefan; Brumagne, Simon

    Processing proprioceptive information in the brain is essential for optimal postural control and can be studied with proprioceptive stimulation, provided by muscle vibration, during functional magnetic resonance imaging (fMRI). Classic electromagnetic muscle vibrators, however, cannot be used in the high-strength magnetic field of the fMRI scanner. Pneumatic vibrators offer an fMRI-compatible alternative. However, whether these devices produce reliable and valid proprioceptive stimuli has not been investigated, although this is essential for these devices to be used in longitudinal research. Test–retest reliability and concurrent validity of the postural response to muscle vibration, provided by custom-made fMRI-compatible pneumatic vibrators, were assessed in a repeated-measures design. Mean center of pressure (CoP) displacements during, respectively, ankle muscle and back muscle vibration (45–60 Hz, 0.5 mm) provided by an electromagnetic and a pneumatic vibrator were measured in ten young healthy subjects. The test was repeated on the same day and again within one week. Intraclass correlation coefficients (ICC) were calculated to assess (a) intra- and interday reliability of the postural responses to, respectively, pneumatic and electromagnetic vibration, and (b) concurrent validity of the response to pneumatic compared to electromagnetic vibration. Test–retest reliability of mean CoP displacements during pneumatic vibration was good to excellent (ICCs = 0.64–0.90) and resembled that of responses to electromagnetic vibration (ICCs = 0.64–0.94). Concurrent validity of the postural effect of pneumatic vibration was good to excellent (ICCs = 0.63–0.95). In conclusion, the proposed fMRI-compatible pneumatic vibrator can be used with confidence to stimulate muscle spindles during fMRI to study central processing of proprioception.

  15. Percutaneous tibial nerve stimulation versus electrical stimulation with pelvic floor muscle training for overactive bladder syndrome in women: results of a randomized controlled study

    Directory of Open Access Journals (Sweden)

    Carlo Vecchioli Scaldazza

    Full Text Available ABSTRACT Introduction This study compared percutaneous tibial nerve stimulation (PTNS versus electrical stimulation with pelvic floor muscle training (ES + PFMT in women with overactive bladder syndrome (OAB. Materials and Methods 60 women with OAB were enrolled. Patients were randomized into two groups. In group A, women underwent ES with PFMT, in group B women underwent PTNS. Results A statistically significant reduction in the number of daily micturitions, episodes of nocturia and urge incontinence was found in the two groups but the difference was more substantial in women treated with PTNS; voided volume increased in both groups. Quality of life improved in both groups, whereas patient perception of urgency improved only in women treated with PTNS. Global impression of improvement revealed a greater satisfaction in patients treated with PTNS. Conclusion This study demonstrates the effectiveness of PTNS and ES with PFMT in women with OAB, but greater improvements were found with PTNS.

  16. Electrical stimulation attenuates morphological alterations and prevents atrophy of the denervated cranial tibial muscle.

    Science.gov (United States)

    Bueno, Cleuber Rodrigo de Souza; Pereira, Mizael; Favaretto, Idvaldo Aparecido; Bortoluci, Carlos Henrique Fachin; Santos, Thais Caroline Pereira Dos; Dias, Daniel Ventura; Daré, Letícia Rossi; Rosa, Geraldo Marco

    2017-01-01

    To investigate if electrical stimulation through Russian current is able to maintain morphology of the cranial tibial muscle of experimentally denervated rats. Thirty-six Wistar rats were divided into four groups: the Initial Control Group, Final Control Group, Experimental Denervated and Treated Group, Experimental Denervated Group. The electrostimulation was performed with a protocol of Russian current applied three times per week, for 45 days. At the end, the animals were euthanized and histological and morphometric analyses were performed. Data were submitted to statistical analysis with a significance level of pprotocolo de corrente russa aplicada três vezes por semanas, durante 45 dias. Ao final, os animais foram eutanasiados e, em seguida, foram realizadas as análises histológica e morfométrica. Os dados foram submetidos à análise estatística, com nível de significância de p<0,05. Os Grupos Experimental Desnervado e o Grupo Experimental Desnervado Tratado apresentaram área de secção transversal da fibra menor quando comparados ao Grupo Controle Final. Entretanto, constatou-se diferença significativa entre o Grupo Experimental Desnervado e o Grupo Experimental Desnervado Tratado, mostrando que a estimulação elétrica minimizou atrofia muscular. Ainda, observou-se que o Grupo Experimental Desnervado Tratado apresentou resultados semelhantes ao Grupo Controle Inicial. A estimulação elétrica por meio da corrente russa foi favorável na manutenção da morfologia do músculo tibial cranial desnervado experimentalmente, minimizando a atrofia muscular.

  17. An Innovative High-Tech Acupuncture Product: SXDZ-100 Nerve Muscle Stimulator, Its Theoretical Basis, Design, and Application

    Directory of Open Access Journals (Sweden)

    Xinyan Gao

    2012-01-01

    Full Text Available We introduce the theoretical basis, design, and application of a patented innovative high-tech product, SXDZ-100 nerve and muscle stimulator. This product is featured with a built-in chip containing transcoding information from different acupuncture manipulation collected from the wide dynamic neurons (WDR in the spinal dorsal horn in animal experiments, which is bioinformation feedback therapy. The discharges of WDR neurons excited by different manipulations are analyzed using chaos theory in this study. It combines the advantages of manual acupuncture (MA like no receptor adaptation and treatment individualization and that of electroacupuncture (EA such as relatively low stimulation intensity and good quantification and thus makes it more effective than common stimulators in acupuncture clinic.

  18. Stimulation of muscle protein synthesis by somatotropin in pigs is independent of the somatotropin-induced increase in circulating insulin.

    Science.gov (United States)

    Wilson, Fiona A; Orellana, Renán A; Suryawan, Agus; Nguyen, Hanh V; Jeyapalan, Asumthia S; Frank, Jason; Davis, Teresa A

    2008-07-01

    Chronic treatment of growing pigs with porcine somatotropin (pST) promotes protein synthesis and doubles postprandial levels of insulin, a hormone that stimulates translation initiation. This study aimed to determine whether the pST-induced increase in skeletal muscle protein synthesis was mediated through an insulin-induced stimulation of translation initiation. After 7-10 days of pST (150 microg x kg(-1) x day(-1)) or control saline treatment, pancreatic glucose-amino acid clamps were performed in overnight-fasted pigs to reproduce 1) fasted (5 microU/ml), 2) fed control (25 microU/ml), and 3) fed pST-treated (50 microU/ml) insulin levels while glucose and amino acids were maintained at baseline fasting levels. Fractional protein synthesis rates and indexes of translation initiation were examined in skeletal muscle. Effectiveness of pST treatment was confirmed by reduced urea nitrogen and elevated insulin-like growth factor I levels in plasma. Skeletal muscle protein synthesis was independently increased by both insulin and pST. Insulin increased the phosphorylation of protein kinase B and the downstream effectors of the mammalian target of rapamycin, ribosomal protein S6 kinase, and eukaryotic initiation factor (eIF)4E-binding protein-1 (4E-BP1). Furthermore, insulin reduced inactive 4E-BP1.eIF4E complex association and increased active eIF4E.eIF4G complex formation, indicating enhanced eIF4F complex assembly. However, pST treatment did not alter translation initiation factor activation. We conclude that the pST-induced stimulation of skeletal muscle protein synthesis in growing pigs is independent of the insulin-associated activation of translation initiation.

  19. Helium-neon laser used to stimulate regeneration of the skeletal muscle damaged by ionizing radiation

    International Nuclear Information System (INIS)

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

    1983-01-01

    A comparative study was made of the therapeutic effects of transplantation of the regenerating muscular tissue and helium-neon lazer rays on the skeletal muscle received 20 Gy x radiation. The results of four series of experiments showed that the effect of lazer rays on the irradiated transversely cut musculus gastrocnemius is simular to that of transplantation of the minced muscular tissue to the defect of the muscle. Regeneration of the muscle in both cases is normalized so that the regenerating muscular organ slightly differs from the control regenerate of unirradiated muscle

  20. 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

  1. Effectiveness of transcutaneous electrical nerve stimulation and microcurrent electrical nerve stimulation in bruxism associated with masticatory muscle pain - A comparative study

    Directory of Open Access Journals (Sweden)

    Rajpurohit Bharat

    2010-01-01

    Full Text Available Objectives: To compare the effectiveness of transcutaneous electrical nerve stimulation (TENS and microcurrent electrical nerve stimulation (MENS on masticatory muscles pain bruxism patient. Materials and Methods : A total of 60 subjects with the clinical diagnosis of bruxism were randomly allocated to two study groups. Group A received TENS (50 Hz, pulse width 0.5 mSec, intensity 0-60 mA for 20 minutes for a period of seven days and Group B received MENS (0.5 Hz, intensity 1,000 μA for 20 minutes for a period of seven days. The outcome measures were assessed in term of Visual Analog Scale (VAS and digital pressometer of 2 Kgf. Results : The study showed significant change in intensity of pain as per VAS score ( P ≤ 0.0001 and tenderness as per digital pressometer ( P ≤ 0.0001. Conclusion : MENS could be used as an effective pain-relieving adjunct to TENS in the treatment of masticatory muscle pain due to bruxism.

  2. Assessment of abdominal muscle function in individuals with motor-complete spinal cord injury above T6 in response to transcranial magnetic stimulation.

    Science.gov (United States)

    Bjerkefors, Anna; Squair, Jordan W; Chua, Romeo; Lam, Tania; Chen, Zhen; Carpenter, Mark G

    2015-02-01

    To use transcranial magnetic stimulation and electromyography to assess the potential for preserved function in the abdominal muscles in individuals classified with motor-complete spinal cord injury above T6. Five individuals with spinal cord injury (C5-T3) and 5 able-bodied individuals. Transcranial magnetic stimulation was delivered over the abdominal region of primary motor cortex during resting and sub-maximal (or attempted) contractions. Surface electromyography was used to record motor-evoked potentials as well as maximal voluntary (or attempted) contractions in the abdominal muscles and the diaphragm. Responses to transcranial magnetic stimulation in the abdominal muscles occurred in all spinal cord injury subjects. Latencies of muscle response onsets were similar in both groups; however, peak-to-peak amplitudes were smaller in the spinal cord injury group. During maximal voluntary (or attempted) contractions all spinal cord injury subjects were able to elicit electromyography activity above resting levels in more than one abdominal muscle across tasks. Individuals with motor-complete spinal cord injury above T6 were able to activate abdominal muscles in response to transcranial magnetic stimulation and during maximal voluntary (or attempted) contractions. The activation was induced directly through corticospinal pathways, and not indirectly by stretch reflex activations of the diaphragm. Transcranial magnetic stimulation and electromyography measurements provide a useful method to assess motor preservation of abdominal muscles in persons with spinal cord injury.

  3. Leucine stimulates protein synthesis in skeletal muscle of neonatal pigs by enhancing mTORC1 activation.

    Science.gov (United States)

    Suryawan, Agus; Jeyapalan, Asumthia S; Orellana, Renan A; Wilson, Fiona A; Nguyen, Hanh V; Davis, Teresa A

    2008-10-01

    Skeletal muscle in the neonate grows at a rapid rate due in part to an enhanced sensitivity to the postprandial rise in amino acids, particularly leucine. To elucidate the molecular mechanism by which leucine stimulates protein synthesis in neonatal muscle, overnight-fasted 7-day-old piglets were treated with rapamycin [an inhibitor of mammalian target of rapamycin (mTOR) complex (mTORC)1] for 1 h and then infused with leucine for 1 h. Fractional rates of protein synthesis and activation of signaling components that lead to mRNA translation were determined in skeletal muscle. Rapamycin completely blocked leucine-induced muscle protein synthesis. Rapamycin markedly reduced raptor-mTOR association, an indicator of mTORC1 activation. Rapamycin blocked the leucine-induced phosphorylation of mTOR, S6 kinase 1 (S6K1), and eukaryotic initiation factor (eIF)4E-binding protein-1 (4E-BP1) and formation of the eIF4E.eIF4G complex and increased eIF4E.4E-BP1 complex abundance. Rapamycin had no effect on the association of mTOR with rictor, a crucial component for mTORC2 activation, or G protein beta-subunit-like protein (GbetaL), a component of mTORC1 and mTORC2. Neither leucine nor rapamycin affected the phosphorylation of AMP-activated protein kinase (AMPK), PKB, or tuberous sclerosis complex (TSC)2, signaling components that reside upstream of mTOR. Eukaryotic elongation factor (eEF)2 phosphorylation was not affected by leucine or rapamycin, although current dogma indicates that eEF2 phosphorylation is mTOR dependent. Together, these in vivo data suggest that leucine stimulates muscle protein synthesis in neonates by enhancing mTORC1 activation and its downstream effectors.

  4. Electrical vs manual acupuncture stimulation in a rat model of polycystic ovary syndrome: different effects on muscle and fat tissue insulin signaling.

    Directory of Open Access Journals (Sweden)

    Julia Johansson

    Full Text Available In rats with dihydrotestosterone (DHT-induced polycystic ovary syndrome (PCOS, repeated low-frequency electrical stimulation of acupuncture needles restores whole-body insulin sensitivity measured by euglycemic hyperinsulinemic clamp. We hypothesized that electrical stimulation causing muscle contractions and manual stimulation causing needle sensation have different effects on insulin sensitivity and related signaling pathways in skeletal muscle and adipose tissue, with electrical stimulation being more effective in DHT-induced PCOS rats. From age 70 days, rats received manual or low-frequency electrical stimulation of needles in abdominal and hind limb muscle five times/wk for 4-5 wks; controls were handled but untreated rats. Low-frequency electrical stimulation modified gene expression (decreased Tbc1d1 in soleus, increased Nr4a3 in mesenteric fat and protein expression (increased pAS160/AS160, Nr4a3 and decreased GLUT4 by western blot and increased GLUT4 expression by immunohistochemistry in soleus muscle; glucose clearance during oral glucose tolerance tests was unaffected. Manual stimulation led to faster glucose clearance and modified mainly gene expression in mesenteric adipose tissue (increased Nr4a3, Mapk3/Erk, Adcy3, Gsk3b, but not protein expression to the same extent; however, Nr4a3 was reduced in soleus muscle. The novel finding is that electrical and manual muscle stimulation affect glucose homeostasis in DHT-induced PCOS rats through different mechanisms. Repeated electrical stimulation regulated key functional molecular pathways important for insulin sensitivity in soleus muscle and mesenteric adipose tissue to a larger extent than manual stimulation. Manual stimulation improved whole-body glucose tolerance, an effect not observed after electrical stimulation, but did not affect molecular signaling pathways to the same extent as electrical stimulation. Although more functional signaling pathways related to insulin sensitivity

  5. Effects of heat stimulation and l-ascorbic acid 2-phosphate supplementation on myogenic differentiation of artificial skeletal muscle tissue constructs.

    Science.gov (United States)

    Ikeda, Kazushi; Ito, Akira; Sato, Masanori; Kanno, Shota; Kawabe, Yoshinori; Kamihira, Masamichi

    2017-05-01

    Although skeletal muscle tissue engineering has been extensively studied, the physical forces produced by tissue-engineered skeletal muscles remain to be improved for potential clinical utility. In this study, we examined the effects of mild heat stimulation and supplementation of a l-ascorbic acid derivative, l-ascorbic acid 2-phosphate (AscP), on myoblast differentiation and physical force generation of tissue-engineered skeletal muscles. Compared with control cultures at 37°C, mouse C2C12 myoblast cells cultured at 39°C enhanced myotube diameter (skeletal muscle hypertrophy), whereas mild heat stimulation did not promote myotube formation (differentiation rate). Conversely, AscP supplementation resulted in an increased differentiation rate but did not induce skeletal muscle hypertrophy. Following combined treatment with mild heat stimulation and AscP supplementation, both skeletal muscle hypertrophy and differentiation rate were enhanced. Moreover, the active tension produced by the tissue-engineered skeletal muscles was improved following combined treatment. These findings indicate that tissue culture using mild heat stimulation and AscP supplementation is a promising approach to enhance the function of tissue-engineered skeletal muscles. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  6. Racl Signaling Is Required for Insulin-Stimulated Glucose Uptake and Is Dysregulated in Insulin-Resistant Murine and Human Skeletal Muscle

    DEFF Research Database (Denmark)

    Sylow, L.; Jensen, T. E.; Kleinert, M.

    2013-01-01

    The actin cytoskeleton-regulating GTPase Racl is required for insulin-stimulated GLUT4 translocation in cultured muscle cells. However, involvement of Racl and its downstream signaling in glucose transport in insulin-sensitive and insulin-resistant mature skeletal muscle has not previously been i...

  7. Dorsal root ganglion neurons innervating skeletal muscle respond to physiological combinations of protons, ATP, and lactate mediated by ASIC, P2X, and TRPV1.

    Science.gov (United States)

    Light, Alan R; Hughen, Ronald W; Zhang, Jie; Rainier, Jon; Liu, Zhuqing; Lee, Jeewoo

    2008-09-01

    The adequate stimuli and molecular receptors for muscle metaboreceptors and nociceptors are still under investigation. We used calcium imaging of cultured primary sensory dorsal root ganglion (DRG) neurons from C57Bl/6 mice to determine candidates for metabolites that could be the adequate stimuli and receptors that could detect these stimuli. Retrograde DiI labeling determined that some of these neurons innervated skeletal muscle. We found that combinations of protons, ATP, and lactate were much more effective than individually applied compounds for activating rapid calcium increases in muscle-innervating dorsal root ganglion neurons. Antagonists for P2X, ASIC, and TRPV1 receptors suggested that these three receptors act together to detect protons, ATP, and lactate when presented together in physiologically relevant concentrations. Two populations of muscle-innervating DRG neurons were found. One responded to low metabolite levels (likely nonnoxious) and used ASIC3, P2X5, and TRPV1 as molecular receptors to detect these metabolites. The other responded to high levels of metabolites (likely noxious) and used ASIC3, P2X4, and TRPV1 as their molecular receptors. We conclude that a combination of ASIC, P2X5 and/or P2X4, and TRPV1 are the molecular receptors used to detect metabolites by muscle-innervating sensory neurons. We further conclude that the adequate stimuli for muscle metaboreceptors and nociceptors are combinations of protons, ATP, and lactate.

  8. Immediate effect of selective neuromuscular electrical stimulation on the electromyographic activity of the vastus medialis oblique muscle

    Directory of Open Access Journals (Sweden)

    Jamilson Simões Brasileiro

    2008-04-01

    Full Text Available The Patellofemoral pain syndrome (PFPS is described as an anterior or retropatellar knee pain in the absence of other associated diseases, and has often been associated with dysfunction of the vastus medialis oblique muscle (VMO. However, several studies have demonstrated the impossibility of selectively activating this muscle with exercises. The aim of the present study was to analyze the immediate effect of neuromuscular electrical stimulation of VMO muscle by means of monitoring the electromyographic activity of the vastus medialis oblique (VMO and vastus lateralis (VL muscles. Eighteen healthy women with a mean age of 23.2 years and mean BMI of 20 Kg/m2 were evaluated. The study protocol included electromyographic analysis of VMO and VL muscles, before and immediately after neuromuscular electrical stimulation of the VMO muscle. During the electromyographic analysis, the volunteers performed maximal voluntary isometric contraction in a 60° knee extension on an isokinetic dynamometer. “Russian current” apparatus was used for electrical stimulation. Results: The data analysis demonstrated a signifi cant increase in VMO activation intensity immediately after it had been electrically stimulated (p=0.0125, whereas VL activation intensity exhibited no signifi cant increase (p=0.924. Moreover, a significant increase in the VMO/VL ratio was also detected (p=0.048. In this study it was observed that electrical stimulation modifiedthe VMO/VL ratio, which suggests electrical stimulation has a benefi cial effect on VMO muscle strength. Resumo A Síndrome da dor patelofemoral (SDPF é descrita como dor anterior ou retro-patelar do joelho na ausência de outras patologias associadas, sendo freqüentemente associada à disfunção do Vasto Medial Oblíquo (VMO. Entretanto, diversos estudos têm demonstrado a impossibilidade de ativar seletivamente este músculo através de exercícios. O objetivo do presente estudo foi analisar o efeito imediato da

  9. Engineering skeletal muscle tissues from murine myoblast progenitor cells and application of electrical stimulation

    NARCIS (Netherlands)

    Schaft, van der D.W.J.; Spreeuwel, van A.C.C.; Boonen, K.J.M.; Langelaan, M.L.P.; Bouten, C.V.C.; Baaijens, F.P.T.

    2013-01-01

    Engineered muscle tissues can be used for several different purposes, which include the production of tissues for use as a disease model in vitro, e.g. to study pressure ulcers, for regenerative medicine and as a meat alternative 1. The first reported 3D muscle constructs have been made many years

  10. Effects of a combined mechanical stimulation protocol: Value for skeletal muscle tissue engineering

    NARCIS (Netherlands)

    Boonen, K.J.M.; Langelaan, M.L.P.; Polak, R.B.; Schaft, van der D.W.J.; Baaijens, F.P.T.; Post, M.J.

    2010-01-01

    Skeletal muscle is an appealing topic for tissue engineering because of its variety in applications for regenerative medicine, in vitro physiological model systems, and in vitro meat production. Besides conventional biochemical cues to promote muscle tissue maturation in vitro, biophysical stimuli

  11. Acute insulin resistance stimulates and insulin sensitization attenuates vascular smooth muscle cell migration and proliferation.

    Science.gov (United States)

    Cersosimo, Eugenio; Xu, Xiaojing; Upala, Sikarin; Triplitt, Curtis; Musi, Nicolas

    2014-08-01

    Differential activation/deactivation of insulin signaling, PI-3K and MAP-K pathways by high glucose and palmitate, with/out the insulin sensitizer pioglitazone (PIO), have been previously shown in vascular smooth muscle cells (VSMCs). To determine the biological impact of these molecular changes, we examined VSMC migration and proliferation ("M"&"P") patterns in similar conditions. VSMCs from healthy human coronary arteries were incubated in growth medium and "M"&"P" were analyzed after exposure to high glucose (25 mmol/L) ± palmitate (200 μmol/L) and ± PIO (8 μmol/L) for 5 h. "M"&"P" were assessed by: (1) polycarbonate membrane barrier with chemo-attractants and extended cell protrusions quantified by optical density (OD595 nm); (2) % change in radius area (2D Assay) using inverted microscopy images; and (3) cell viability assay expressed as cell absorbance (ABS) in media. "M" in 25 mmol/L glucose media increased by ~25% from baseline and % change in radius area rose from ~20% to ~30%. The addition of PIO was accompanied by a significant decrease in "M" from 0.25 ± 0.02 to 0.19 ± 0.02; a comparable decline from 0.25 ± 0.02 to 0.18 ± 0.02 was also seen with 25 mmol/L of glucose +200 μmol/L of palmitate. When PIO was coincubated with high glucose plus palmitate there was a 50% reduction in % change in radius. A ~10% increase in ABS, reflecting augmented "P" in media with 25 mmol/L glucose versus control was documented. The addition of PIO reduced ABS from 0.208 ± 0.03 to 0.183 ± 0.06. Both high glucose and palmitate showed ABS of ~0.140 ± 0.02, which decreased with PIO to ~0.120 ± 0.02, indicating "P" was reduced. These results confirm that high glucose and palmitate stimulate VSMCs migration and proliferation in vitro, which is attenuated by coincubation with the insulin sensitizer PIO. Although, we cannot ascertain whether these functional changes are coincident with the activation/deactivation of signal molecules, our findings are consistent with the

  12. Rac1 and AMPK Account for the Majority of Muscle Glucose Uptake Stimulated by Ex Vivo Contraction but Not In Vivo Exercise.

    Science.gov (United States)

    Sylow, Lykke; Møller, Lisbeth L V; Kleinert, Maximilian; D'Hulst, Gommaar; De Groote, Estelle; Schjerling, Peter; Steinberg, Gregory R; Jensen, Thomas E; Richter, Erik A

    2017-06-01

    Exercise bypasses insulin resistance to increase glucose uptake in skeletal muscle and therefore represents an important alternative to stimulate glucose uptake in insulin-resistant muscle. Both Rac1 and AMPK have been shown to partly regulate contraction-stimulated muscle glucose uptake, but whether those two signaling pathways jointly account for the entire signal to glucose transport is unknown. We therefore studied the ability of contraction and exercise to stimulate glucose transport in isolated muscles with AMPK loss of function combined with either pharmacological inhibition or genetic deletion of Rac1.Muscle-specific knockout (mKO) of Rac1, a kinase-dead α2 AMPK (α2KD), and double knockout (KO) of β1 and β2 AMPK subunits (β1β2 KO) each partially decreased contraction-stimulated glucose transport in mouse soleus and extensor digitorum longus (EDL) muscle. Interestingly, when pharmacological Rac1 inhibition was combined with either AMPK β1β2 KO or α2KD, contraction-stimulated glucose transport was almost completely inhibited. Importantly, α2KD+Rac1 mKO double-transgenic mice also displayed severely impaired contraction-stimulated glucose transport, whereas exercise-stimulated glucose uptake in vivo was only partially reduced by Rac1 mKO with no additive effect of α2KD. It is concluded that Rac1 and AMPK together account for almost the entire ex vivo contraction response in muscle glucose transport, whereas only Rac1, but not α2 AMPK, regulates muscle glucose uptake during submaximal exercise in vivo. © 2017 by the American Diabetes Association.

  13. Can repetitive transcranial magnetic stimulation increase muscle strength in functional neurological paresis? A proof-of-principle study.

    Science.gov (United States)

    Broersma, M; Koops, E A; Vroomen, P C; Van der Hoeven, J H; Aleman, A; Leenders, K L; Maurits, N M; van Beilen, M

    2015-05-01

    Therapeutic options are limited in functional neurological paresis disorder. Earlier intervention studies did not control for a placebo effect, hampering assessment of effectivity. A proof-of-principle investigation was conducted into the therapeutic potential of repetitive transcranial magnetic stimulation (rTMS), using a single-blind two-period placebo-controlled cross-over design. Eleven patients received active 15 Hz rTMS over the contralateral motor cortex (hand area), in two periods of 5 days, for 30 min once a day at 80% of resting motor threshold, with a train length of 2 s and an intertrain interval of 4 s. Eight of these eleven patients were also included in the placebo treatment condition. Primary outcome measure was change in muscle strength as measured by dynamometry after treatment. Secondary outcome measure was the subjective change in muscle strength after treatment. In patients who received both treatments, active rTMS induced a significantly larger median increase in objectively measured muscle strength (24%) compared to placebo rTMS (6%; P difference due to treatment, i.e. patients did not perceive these objectively measured motor improvements (P = 0.40). Our findings suggest that rTMS by itself can potentially improve muscle weakness in functional neurological paresis disorder. Whereas patients' muscle strength increased as measured with dynamometry, patients did not report increased functioning of the affected hand, subjectively. The results may indicate that decreased muscle strength is not the core symptom and that rTMS should be added to behavioral approaches in functional neurological paresis. © 2015 EAN.

  14. Glucose stimulates protein synthesis in skeletal muscle of neonatal pigs through an AMPK- and mTOR-independent process.

    Science.gov (United States)

    Jeyapalan, Asumthia S; Orellana, Renan A; Suryawan, Agus; O'Connor, Pamela M J; Nguyen, Hanh V; Escobar, Jeffery; Frank, Jason W; Davis, Teresa A

    2007-08-01

    Skeletal muscle protein synthesis is elevated in neonates in part due to an enhanced response to the rise in insulin and amino acids after eating. In vitro studies suggest that glucose plays a role in protein synthesis regulation. To determine whether glucose, independently of insulin and amino acids, is involved in the postprandial rise in skeletal muscle protein synthesis, pancreatic-substrate clamps were performed in neonatal pigs. Insulin secretion was inhibited with somatostatin and insulin was infused to reproduce fasting or fed levels, while glucose and amino acids were clamped at fasting or fed levels. Fractional protein synthesis rates and translational control mechanisms were examined. Raising glucose alone increased protein synthesis in fast-twitch glycolytic muscles but not in other tissues. The response in muscle was associated with increased phosphorylation of protein kinase B (PKB) and enhanced formation of the active eIF4E.eIF4G complex but no change in phosphorylation of AMP-activated protein kinase (AMPK), tuberous sclerosis complex 2 (TSC2), mammalian target of rapamycin (mTOR), 4E-binding protein-1 (4E-BP1), ribosomal protein S6 kinase (S6K1), or eukaryotic elongation factor 2 (eEF2). Raising glucose, insulin, and amino acids increased protein synthesis in most tissues. The response in muscle was associated with phosphorylation of PKB, mTOR, S6K1, and 4E-BP1 and enhanced eIF4E.eIF4G formation. The results suggest that the postprandial rise in glucose, independently of insulin and amino acids, stimulates protein synthesis in neonates, and this response is specific to fast-twitch glycolytic muscle and occurs by AMPK- and mTOR-independent pathways.

  15. Neuromuscular electrical stimulation and inspiratory muscle training as potential adjunctive rehabilitation options for patients with heart failure.

    Science.gov (United States)

    Arena, Ross; Pinkstaff, Sherry; Wheeler, Emma; Peberdy, Mary Ann; Guazzi, Marco; Myers, Jonathan

    2010-01-01

    Aerobic and resistance exercise training programs produce an abundance of physiologic and clinical benefits in patients with heart failure (HF). Improved maximal aerobic capacity, submaximal aerobic endurance, muscle force production, perceived quality of life, and skeletal muscle characteristics are among the more established outcomes resulting from these rehabilitation techniques. Moreover, both aerobic and resistance exercise training appear to portend a low risk to patients with HF when appropriate exercise prescription methods are followed. While the aforementioned training techniques will undoubtedly continue to be at the center of a well-formulated rehabilitation program, other adjunctive interventions, which are presently underutilized in clinical practice, may prove beneficial in patients with HF. Specifically, both neuromuscular electrical stimulation (NMES) and inspiratory muscle training (IMT) appear to significantly improve several physiologic, exercise, symptomatologic, and quality-of-life parameters. NMES targets skeletal muscle abnormalities, whereas IMT primarily targets the weakened respiratory musculature, both often encountered in patients with HF. A PubMed search using relevant key words identified 19 original investigations examining the impact of NMES (13 studies) and IMT (6 studies) training programs in patients with HF. The resultant review (1) provides a summary of the original research outcomes of both NMES and IMT in patients with HF; (2) addresses current research gaps, providing a direction for future investigations; and (3) provides clinical scenarios where NMES and IMT may prove to be beneficial during the rehabilitation of patients with HF.

  16. Gamma-sarcoglycan is required for the response of archvillin to mechanical stimulation in skeletal muscle

    Science.gov (United States)

    Spinazzola, Janelle M.; Smith, Tara C.; Liu, Min; Luna, Elizabeth J.; Barton, Elisabeth R.

    2015-01-01

    Loss of gamma-sarcoglycan (γ-SG) induces muscle degeneration and signaling defects in response to mechanical load, and its absence is common to both Duchenne and limb girdle muscular dystrophies. Growing evidence suggests that aberrant signaling contributes to the disease pathology; however, the mechanisms of γ-SG-mediated mechanical signaling are poorly understood. To uncover γ-SG signaling pathway components, we performed yeast two-hybrid screens and identified the muscle-specific protein archvillin as a γ-SG and dystrophin interacting protein. Archvillin protein and message levels were significantly upregulated at the sarcolemma of murine γ-SG-null (gsg−/−) muscle but delocalized in dystrophin-deficient mdx muscle. Similar elevation of archvillin protein was observed in human quadriceps muscle lacking γ-SG. Reintroduction of γ-SG in gsg−/− muscle by rAAV injection restored archvillin levels to that of control C57 muscle. In situ eccentric contraction of tibialis anterior (TA) muscles from C57 mice caused ERK1/2 phosphorylation, nuclear activation of P-ERK1/2 and stimulus-dependent archvillin association with P-ERK1/2. In contrast, TA muscles from gsg−/− and mdx mice exhibited heightened P-ERK1/2 and increased nuclear P-ERK1/2 localization following eccentric contractions, but the archvillin–P-ERK1/2 association was completely ablated. These results position archvillin as a mechanically sensitive component of the dystrophin complex and demonstrate that signaling defects caused by loss of γ-SG occur both at the sarcolemma and in the nucleus. PMID:25605665

  17. Insulin does not stimulate muscle protein synthesis during increased plasma branched-chain amino acids alone but still decreases whole body proteolysis in humans.

    Science.gov (United States)

    Everman, Sarah; Meyer, Christian; Tran, Lee; Hoffman, Nyssa; Carroll, Chad C; Dedmon, William L; Katsanos, Christos S

    2016-10-01

    Insulin stimulates muscle protein synthesis when the levels of total amino acids, or at least the essential amino acids, are at or above their postabsorptive concentrations. Among the essential amino acids, branched-chain amino acids (BCAA) have the primary role in stimulating muscle protein synthesis and are commonly sought alone to stimulate muscle protein synthesis in humans. Fourteen healthy young subjects were studied before and after insulin infusion to examine whether insulin stimulates muscle protein synthesis in relation to the availability of BCAA alone. One half of the subjects were studied in the presence of postabsorptive BCAA concentrations (control) and the other half in the presence of increased plasma BCAA (BCAA). Compared with that prior to the initiation of the insulin infusion, fractional synthesis rate of muscle protein (%/h) did not change (P > 0.05) during insulin in either the control (0.04 ± 0.01 vs 0.05 ± 0.01) or the BCAA (0.05 ± 0.02 vs. 0.05 ± 0.01) experiments. Insulin decreased (P BCAA (0.89 ± 0.07 vs 0.61 ± 0.03) experiments, but the change was not different between the two experiments (P > 0.05). In conclusion, insulin does not stimulate muscle protein synthesis in the presence of increased circulating levels of plasma BCAA alone. Insulin's suppressive effect on proteolysis is observed independently of the levels of circulating plasma BCAA. Copyright © 2016 the American Physiological Society.

  18. Electrically Stimulated Antagonist Muscle Contraction Increased Muscle Mass and Bone Mineral Density of One Astronaut - Initial Verification on the International Space Station.

    Science.gov (United States)

    Shiba, Naoto; Matsuse, Hiroo; Takano, Yoshio; Yoshimitsu, Kazuhiro; Omoto, Masayuki; Hashida, Ryuki; Tagawa, Yoshihiko; Inada, Tomohisa; Yamada, Shin; Ohshima, Hiroshi

    2015-01-01

    Musculoskeletal atrophy is one of the major problems of extended periods of exposure to weightlessness such as on the International Space Station (ISS). We developed the Hybrid Training System (HTS) to maintain an astronaut's musculoskeletal system using an electrically stimulated antagonist to resist the volitional contraction of the agonist instead of gravity. The present study assessed the system's orbital operation capability and utility, as well as its preventative effect on an astronaut's musculoskeletal atrophy. HTS was attached to the non-dominant arm of an astronaut staying on the ISS, and his dominant arm without HTS was established as the control (CTR). 10 sets of 10 reciprocal elbow curls were one training session, and 12 total sessions of training (3 times per week for 4 weeks) were performed. Pre and post flight ground based evaluations were performed by Biodex (muscle performance), MRI (muscle volume), and DXA (BMD, lean [muscle] mass, fat mass). Pre and post training inflight evaluations were performed by a hand held dynamometer (muscle force) and a measuring tape (upper arm circumference). The experiment was completed on schedule, and HTS functioned well without problems. Isokinetic elbow extension torque (Nm) changed -19.4% in HTS, and -21.7% in CTR. Isokinetic elbow flexion torque changed -23.7% in HTS, and there was no change in CTR. Total Work (Joule) of elbow extension changed -8.3% in HTS, and +0.3% in CTR. For elbow flexion it changed -23.3% in HTS and -32.6% in CTR. Average Power (Watts) of elbow extension changed +22.1% in HTS and -8.0% in CTR. For elbow flexion it changed -6.5% in HTS and -4.8% in CTR. Triceps muscle volume according to MRI changed +11.7% and that of biceps was +2.1% using HTS, however -0.1% and -0.4% respectively for CTR. BMD changed +4.6% in the HTS arm and -1.2% for CTR. Lean (muscle) mass of the arm changed only +10.6% in HTS. Fat mass changed -12.6% in HTS and -6.4% in CTR. These results showed the orbital operation

  19. Electrically Stimulated Antagonist Muscle Contraction Increased Muscle Mass and Bone Mineral Density of One Astronaut - Initial Verification on the International Space Station.

    Directory of Open Access Journals (Sweden)

    Naoto Shiba

    Full Text Available Musculoskeletal atrophy is one of the major problems of extended periods of exposure to weightlessness such as on the International Space Station (ISS. We developed the Hybrid Training System (HTS to maintain an astronaut's musculoskeletal system using an electrically stimulated antagonist to resist the volitional contraction of the agonist instead of gravity. The present study assessed the system's orbital operation capability and utility, as well as its preventative effect on an astronaut's musculoskeletal atrophy.HTS was attached to the non-dominant arm of an astronaut staying on the ISS, and his dominant arm without HTS was established as the control (CTR. 10 sets of 10 reciprocal elbow curls were one training session, and 12 total sessions of training (3 times per week for 4 weeks were performed. Pre and post flight ground based evaluations were performed by Biodex (muscle performance, MRI (muscle volume, and DXA (BMD, lean [muscle] mass, fat mass. Pre and post training inflight evaluations were performed by a hand held dynamometer (muscle force and a measuring tape (upper arm circumference.The experiment was completed on schedule, and HTS functioned well without problems. Isokinetic elbow extension torque (Nm changed -19.4% in HTS, and -21.7% in CTR. Isokinetic elbow flexion torque changed -23.7% in HTS, and there was no change in CTR. Total Work (Joule of elbow extension changed -8.3% in HTS, and +0.3% in CTR. For elbow flexion it changed -23.3% in HTS and -32.6% in CTR. Average Power (Watts of elbow extension changed +22.1% in HTS and -8.0% in CTR. For elbow flexion it changed -6.5% in HTS and -4.8% in CTR. Triceps muscle volume according to MRI changed +11.7% and that of biceps was +2.1% using HTS, however -0.1% and -0.4% respectively for CTR. BMD changed +4.6% in the HTS arm and -1.2% for CTR. Lean (muscle mass of the arm changed only +10.6% in HTS. Fat mass changed -12.6% in HTS and -6.4% in CTR.These results showed the orbital

  20. Supplemental Stimulation Improves Swing Phase Kinematics During Exoskeleton Assisted Gait of SCI Subjects With Severe Muscle Spasticity

    Science.gov (United States)

    Ekelem, Andrew; Goldfarb, Michael

    2018-01-01

    Spasticity is a common comorbidity associated with spinal cord injury (SCI). Robotic exoskeletons have recently emerged to facilitate legged mobility in people with motor complete SCI. Involuntary muscle activity attributed to spasticity, however, can prevent such individuals from using an exoskeleton. Specifically, although most exoskeleton technologies can accommodate low to moderate spasticity, the presence of moderate to severe spasticity can significantly impair gait kinematics when using an exoskeleton. In an effort to potentially enable individuals with moderate to severe spasticity to use exoskeletons more effectively, this study investigates the use of common peroneal stimulation in conjunction with exoskeleton gait assistance. The electrical stimulation is timed with the exoskeleton swing phase, and is intended to acutely suppress extensor spasticity through recruitment of the flexion withdrawal reflex (i.e., while the stimulation is activated) to enable improved exoskeletal walking. In order to examine the potential efficacy of this approach, two SCI subjects with severe extensor spasticity (i.e., modified Ashworth ratings of three to four) walked in an exoskeleton with and without supplemental stimulation while knee and hip motion was measured during swing phase. Stimulation was alternated on and off every ten steps to eliminate transient therapeutic effects, enabling the acute effects of stimulation to be isolated. These experiments indicated that common peroneal stimulation on average increased peak hip flexion during the swing phase of walking by 21.1° (236%) and peak knee flexion by 14.4° (56%). Additionally, use of the stimulation decreased the swing phase RMS motor current by 228 mA (15%) at the hip motors and 734 mA (38%) at the knee motors, indicating improved kinematics were achieved with reduced effort from the exoskeleton. Walking with the exoskeleton did not have a significant effect on modified Ashworth scores, indicating the common

  1. Supplemental Stimulation Improves Swing Phase Kinematics During Exoskeleton Assisted Gait of SCI Subjects With Severe Muscle Spasticity.

    Science.gov (United States)

    Ekelem, Andrew; Goldfarb, Michael

    2018-01-01

    Spasticity is a common comorbidity associated with spinal cord injury (SCI). Robotic exoskeletons have recently emerged to facilitate legged mobility in people with motor complete SCI. Involuntary muscle activity attributed to spasticity, however, can prevent such individuals from using an exoskeleton. Specifically, although most exoskeleton technologies can accommodate low to moderate spasticity, the presence of moderate to severe spasticity can significantly impair gait kinematics when using an exoskeleton. In an effort to potentially enable individuals with moderate to severe spasticity to use exoskeletons more effectively, this study investigates the use of common peroneal stimulation in conjunction with exoskeleton gait assistance. The electrical stimulation is timed with the exoskeleton swing phase, and is intended to acutely suppress extensor spasticity through recruitment of the flexion withdrawal reflex (i.e., while the stimulation is activated) to enable improved exoskeletal walking. In order to examine the potential efficacy of this approach, two SCI subjects with severe extensor spasticity (i.e., modified Ashworth ratings of three to four) walked in an exoskeleton with and without supplemental stimulation while knee and hip motion was measured during swing phase. Stimulation was alternated on and off every ten steps to eliminate transient therapeutic effects, enabling the acute effects of stimulation to be isolated. These experiments indicated that common peroneal stimulation on average increased peak hip flexion during the swing phase of walking by 21.1° (236%) and peak knee flexion by 14.4° (56%). Additionally, use of the stimulation decreased the swing phase RMS motor current by 228 mA (15%) at the hip motors and 734 mA (38%) at the knee motors, indicating improved kinematics were achieved with reduced effort from the exoskeleton. Walking with the exoskeleton did not have a significant effect on modified Ashworth scores, indicating the common

  2. Supplemental Stimulation Improves Swing Phase Kinematics During Exoskeleton Assisted Gait of SCI Subjects With Severe Muscle Spasticity

    Directory of Open Access Journals (Sweden)

    Andrew Ekelem

    2018-06-01

    Full Text Available Spasticity is a common comorbidity associated with spinal cord injury (SCI. Robotic exoskeletons have recently emerged to facilitate legged mobility in people with motor complete SCI. Involuntary muscle activity attributed to spasticity, however, can prevent such individuals from using an exoskeleton. Specifically, although most exoskeleton technologies can accommodate low to moderate spasticity, the presence of moderate to severe spasticity can significantly impair gait kinematics when using an exoskeleton. In an effort to potentially enable individuals with moderate to severe spasticity to use exoskeletons more effectively, this study investigates the use of common peroneal stimulation in conjunction with exoskeleton gait assistance. The electrical stimulation is timed with the exoskeleton swing phase, and is intended to acutely suppress extensor spasticity through recruitment of the flexion withdrawal reflex (i.e., while the stimulation is activated to enable improved exoskeletal walking. In order to examine the potential efficacy of this approach, two SCI subjects with severe extensor spasticity (i.e., modified Ashworth ratings of three to four walked in an exoskeleton with and without supplemental stimulation while knee and hip motion was measured during swing phase. Stimulation was alternated on and off every ten steps to eliminate transient therapeutic effects, enabling the acute effects of stimulation to be isolated. These experiments indicated that common peroneal stimulation on average increased peak hip flexion during the swing phase of walking by 21.1° (236% and peak knee flexion by 14.4° (56%. Additionally, use of the stimulation decreased the swing phase RMS motor current by 228 mA (15% at the hip motors and 734 mA (38% at the knee motors, indicating improved kinematics were achieved with reduced effort from the exoskeleton. Walking with the exoskeleton did not have a significant effect on modified Ashworth scores, indicating the

  3. 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

  4. Caffeine and contraction synergistically stimulate 5'-AMP-activated protein kinase and insulin-independent glucose transport in rat skeletal muscle.

    Science.gov (United States)

    Tsuda, Satoshi; Egawa, Tatsuro; Kitani, Kazuto; Oshima, Rieko; Ma, Xiao; Hayashi, Tatsuya

    2015-10-01

    5'-Adenosine monophosphate-activated protein kinase (AMPK) has been identified as a key mediator of contraction-stimulated insulin-independent glucose transport in skeletal muscle. Caffeine acutely stimulates AMPK in resting skeletal muscle, but it is unknown whether caffeine affects AMPK in contracting muscle. Isolated rat epitrochlearis muscle was preincubated and then incubated in the absence or presence of 3 mmol/L caffeine for 30 or 120 min. Electrical stimulation (ES) was used to evoke tetanic contractions during the last 10 min of the incubation period. The combination of caffeine plus contraction had additive effects on AMPKα Thr(172) phosphorylation, α-isoform-specific AMPK activity, and 3-O-methylglucose (3MG) transport. In contrast, caffeine inhibited basal and contraction-stimulated Akt Ser(473) phosphorylation. Caffeine significantly delayed muscle fatigue during contraction, and the combination of caffeine and contraction additively decreased ATP and phosphocreatine contents. Caffeine did not affect resting tension. Next, rats were given an intraperitoneal injection of caffeine (60 mg/kg body weight) or saline, and the extensor digitorum longus muscle was dissected 15 min later. ES of the sciatic nerve was performed to evoke tetanic contractions for 5 min before dissection. Similar to the findings from isolated muscles incubated in vitro, the combination of caffeine plus contraction in vivo had additive effects on AMPK phosphorylation, AMPK activity, and 3MG transport. Caffeine also inhibited basal and contraction-stimulated Akt phosphorylation in vivo. These findings suggest that caffeine and contraction synergistically stimulate AMPK activity and insulin-independent glucose transport, at least in part by decreasing muscle fatigue and thereby promoting energy consumption during contraction. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological

  5. Burn-induced stimulation of lysosomal enzyme synthesis in skeletal muscle

    International Nuclear Information System (INIS)

    Odessey, R.

    1986-01-01

    A localized burn injury to a rat hindlimb results in atrophy of soleus muscle (in the absence of cellular damage) which is attributable to an increase in muscle protein breakdown. Previous work has shown that lysosomal enzyme activities (cathepsins B, H, L, and D) are elevated in muscle from the burned leg by 50% to 100%. There is no change in endogenous neutral protease activity (+/- Ca ++ ). The increase in protease activity can not be attributed to changes in endogenous protease inhibitors. The latency [(Triton X100 treated - control)/triton treated] of lysosomal enzymes is approximately 50% and is not altered by burn injury. The rate of sucrose uptake is also not altered by burn. These experiments suggest that the rate of substrate supply to the lysosomal apparatus via endocytosis or autophagocytosis is not altered by burn. When muscles are preincubated with 3 H-phenylalanine or 3 H-mannose burn increased incorporation into protein of the fraction containing lysosomes by 100%. Preincubation in the presence of tunicamycin (an inhibitor of glycoprotein synthesis) inhibited incorporation of both labels into a microsomal fraction of the muscle from the burned leg, but has little effect on incorporation in the control muscle. These findings are consistent with the hypothesis that the burn-induced increase in protein breakdown is caused by an increase in lysosomal protease synthesis

  6. Metabolic costs of force generation for constant-frequency and catchlike-inducing electrical stimulation in human tibialis anterior muscle

    DEFF Research Database (Denmark)

    Ratkevicius, Aivaras; Quistorff, Bjørn

    2002-01-01

    -frequency trains, catchlike-inducing trains produced a faster force generation and were more effective in maintaining the force--time integral as well as peak force. However, ATP costs of force generation were similar for the catchlike-inducing and constant-frequency stimulation (6.7 plus/minus 1.1 and 6.6 plus......Metabolic costs of force generation were compared for constant-frequency and catchlike-inducing electrical stimulation. Repetitive catchlike-inducing trains consisted of 2 interpulse intervals (IPIs) at 12.5 ms, 1 IPI at 25 ms, and 5 IPIs at 50 ms. Constant-frequency trains consisted of 8 IPIs...... at 37.5 ms. One train was delivered to the peroneal nerve every 2.5 s for 36 times under ischemic conditions. Anaerobic adenosine triphosphate (ATP) turnover was determined using 31-phosphorus magnetic resonance spectroscopy (P-MRS) of the human tibialis anterior muscle. Compared with constant...

  7. 3D false color computed tomography for diagnosis and follow-up of permanent denervated human muscles submitted to home-based Functional Electrical Stimulation

    Directory of Open Access Journals (Sweden)

    Ugo Carraro

    2015-03-01

    Full Text Available This report outlines the use of a customized false-color 3D computed tomography (CT protocol for the imaging of the rectus femoris of spinal cord injury (SCI patients suffering from complete and permanent denervation, as characterized by complete Conus and Cauda Equina syndrome. This muscle imaging method elicits the progression of the syndrome from initial atrophy to eventual degeneration, as well as the extent to which patients' quadriceps could be recovered during four years of home-based functional electrical stimulation (h-b FES. Patients were pre-selected from several European hospitals and functionally tested by, and enrolled in the EU Commission Shared Cost Project RISE (Contract n. QLG5-CT-2001-02191 at the Department of Physical Medicine, Wilhelminenspital, Vienna, Austria. Denervated muscles were electrically stimulated using a custom-designed stimulator, large surface electrodes, and customized progressive stimulation settings. Spiral CT images and specialized computational tools were used to isolate the rectus femoris muscle and produce 3D and 2D reconstructions of the denervated muscles. The cross sections of the muscles were determined by 2D Color CT, while muscle volumes were reconstructed by 3D Color CT. Shape, volume, and density changes were measured over the entirety of each rectus femoris muscle. Changes in tissue composition within the muscle were visualized by associating different colors to specified Hounsfield unit (HU values for fat, (yellow: [-200; -10], loose connective tissue or atrophic muscle, (cyan: [-9; 40], and normal muscle, fascia and tendons included, (red: [41; 200]. The results from this analysis are presented as the average HU values within the rectus femoris muscle reconstruction, as well as the percentage of these tissues with respect to the total muscle volume. Results from this study demonstrate that h-b FES induces a compliance-dependent recovery of muscle volume and size of muscle fibers, as

  8. 3D False Color Computed Tomography for Diagnosis and Follow-Up of Permanent Denervated Human Muscles Submitted to Home-Based Functional Electrical Stimulation.

    Science.gov (United States)

    Carraro, Ugo; Edmunds, Kyle J; Gargiulo, Paolo

    2015-03-11

    This report outlines the use of a customized false-color 3D computed tomography (CT) protocol for the imaging of the rectus femoris of spinal cord injury (SCI) patients suffering from complete and permanent denervation, as characterized by complete Conus and Cauda Equina syndrome. This muscle imaging method elicits the progression of the syndrome from initial atrophy to eventual degeneration, as well as the extent to which patients' quadriceps could be recovered during four years of home-based functional electrical stimulation (h-b FES). Patients were pre-selected from several European hospitals and functionally tested by, and enrolled in the EU Commission Shared Cost Project RISE (Contract n. QLG5-CT-2001-02191) at the Department of Physical Medicine, Wilhelminenspital, Vienna, Austria. Denervated muscles were electrically stimulated using a custom-designed stimulator, large surface electrodes, and customized progressive stimulation settings. Spiral CT images and specialized computational tools were used to isolate the rectus femoris muscle and produce 3D and 2D reconstructions of the denervated muscles. The cross sections of the muscles were determined by 2D Color CT, while muscle volumes were reconstructed by 3D Color CT. Shape, volume, and density changes were measured over the entirety of each rectus femoris muscle. Changes in tissue composition within the muscle were visualized by associating different colors to specified Hounsfield unit (HU) values for fat, (yellow: [-200; -10]), loose connective tissue or atrophic muscle, (cyan: [-9; 40]), and normal muscle, fascia and tendons included, (red: [41; 200]). The results from this analysis are presented as the average HU values within the rectus femoris muscle reconstruction, as well as the percentage of these tissues with respect to the total muscle volume. Results from this study demonstrate that h-b FES induces a compliance-dependent recovery of muscle volume and size of muscle fibers, as evidenced by the

  9. Normal insulin-stimulated endothelial function and impaired insulin-stimulated muscle glucose uptake in young adults with low birth weight

    DEFF Research Database (Denmark)

    Hermann, T S; Rask-Madsen, C; Ihlemann, N

    2003-01-01

    of acetylcholine and sodium nitroprusside in the forearm of fourteen 21-yr-old men with low birth weight and 16 controls of normal birth weight. Glucose uptake was measured during intraarterial insulin infusion. Dose-response studies were repeated during insulin infusion. The maximal blood flow during......Low birth weight has been linked to insulin resistance and cardiovascular disease. We hypothesized that insulin sensitivity of both muscle and vascular tissues were impaired in young men with low birth weight. Blood flow was measured by venous occlusion plethysmography during dose-response studies...... acetylcholine infusion was 14.1 +/- 2.7 and 14.4 +/- 2.1 [ml x (100 ml forearm)(-1) x min(-1)] in low and normal birth weight subjects, respectively. Insulin coinfusion increased acetylcholine-stimulated flow in both groups: 18.0 +/- 3.1 vs. 17.9 +/- 3.1 [ml x (100 ml forearm)(-1) x min(-1)], NS. Insulin...

  10. Pelvic floor muscle exercises with or without electric stimulation and post-prostectomy urinary incontinence: a systematic review

    Directory of Open Access Journals (Sweden)

    Patrícia Zaidan

    Full Text Available Abstract Introduction: Urinary incontinence (UI after prostatectomy is difficult to treat and causes profound adverse impacts on the individual's quality of life. The main clinical treatments available for post-prostatectomy UI consist of behavioral techniques and physical therapy techniques, such as exercises, electrical stimulation and biofeedback for pelvic floor muscles (PFMs. Objective: To investigate the effectiveness of PFM exercises with or without electrical stimulation for reducing post-prostatectomy UI. Methods: We included only randomized controlled trials (RCTs which used PFM exercises with or without electrical stimulation. The search was conducted in August of 2013 in the databases of the U.S. National Library of Medicine (MEDLINE, Scientific Electronic Library Online (SciELO, Physiotherapy Evidence Database (PEDro and Virtual Health Library (VHL. We searched for RCTs published between 1999 and 2013. As keywords for our search, we used the following descriptors from the Health Sciences Descriptors (DeCS: urinary incontinence, pelvic diaphragm, prostatectomy, pelvic floor exercises, electrostimulation and electrical stimulation. We also used the following descriptors from the Medical Subject Headings (MeSH: electrical stimulation, pelvic floor, urinary incontinence, prostatectomy, physiotherapy and exercise therapy. Results: Of the 59 RCTs found, 26 were excluded as duplicates, and 28 were excluded for not displaying a minimum score of 5.0 on the PEDro Scale, which left us with five RCTs. Conclusion: PFM exercises can be effective for treating UI after radical prostatectomy, especially if begun soon after surgery. Associating electrical stimulation with PFM exercises did not show additional benefit for treating urinary incontinence. However, the selected studies presented some methodological weaknesses that may have compromised their internal validity.

  11. Neuromuscular electrical stimulation for preventing skeletal-muscle weakness and wasting in critically ill patients

    DEFF Research Database (Denmark)

    Maffiuletti, Nicola A.; Roig, Marc; Karatzanos, Eleftherios

    2013-01-01

    ill patients, in comparison with usual care. Methods: We searched PubMed, CENTRAL, CINAHL, Web of Science, and PEDro to identify randomized controlled trials exploring the effect of NMES in critically ill patients, which had a well-defined NMES protocol, provided outcomes related to skeletal......-muscle strength and/or mass, and for which full text was available. Two independent reviewers extracted data on muscle-related outcomes (strength and mass), and participant and intervention characteristics, and assessed the methodological quality of the studies. Owing to the lack of means and standard deviations...... yielded 8 eligible studies involving 172 patients. The methodological quality of the studies was moderate to high. Five studies reported an increase in strength or better preservation of strength with NMES, with one study having a large effect size. Two studies found better preservation of muscle mass...

  12. The influence of low temperature, type of muscle and electrical stimulation on the course of rigor mortis, ageing and tenderness of beef muscles.

    Science.gov (United States)

    Olsson, U; Hertzman, C; Tornberg, E

    1994-01-01

    The course of rigor mortis, ageing and tenderness have been evaluated for two beef muscles, M. semimembranosus (SM) and M. longissimus dorsi (LD), when entering rigor at constant temperatures in the cold-shortening region (1, 4, 7 and 10°C). The influence of electrical stimulation (ES) was also examined. Post-mortem changes were registered by shortening and isometric tension and by following the decline of pH, ATP and creatine phosphate. The effect of ageing on tenderness was recorded by measuring shear-force (2, 8 and 15 days post mortem) and the sensory properties were assessed 15 days post mortem. It was found that shortening increased with decreasing temperature, resulting in decreased tenderness. Tenderness for LD, but not for SM, was improved by ES at 1 and 4°C, whereas ES did not give rise to any decrease in the degree of shortening during rigor mortis development. This suggests that ES influences tenderization more than it prevents cold-shortening. The samples with a pre-rigor mortis temperature of 1°C could not be tenderized, when stored up to 15 days, whereas this was the case for the muscles entering rigor mortis at the other higher temperatures. The results show that under the conditions used in this study, the course of rigor mortis is more important for the ultimate tenderness than the course of ageing. Copyright © 1994. Published by Elsevier Ltd.

  13. Terbinafine: effects on platelet-derived growth factor-stimulated smooth muscle cells in vitro and myointimal proliferation in vivo

    International Nuclear Information System (INIS)

    McCarthy, L.; Van Halen, R.G.; St Denny, I.H.; Glinka, K.G.; Handley, D.A.; Stuetz, A.; Nemecek, G.M.

    1987-01-01

    Terbinafine (T; (E)-N-(6,6-dimethyl-2-hepten-4-ynyl)-N-methyl-1-naphthalenemethanamine), an antimycotic agent with antimitogenic activity in fibroblasts, was examined for its effects on platelet-derived growth factor (PDGF)-stimulated aortic smooth muscle cell DNA synthesis in vitro and myointimal proliferation in vivo. Exposure of smooth muscle cells to 1-25 μM T resulted in a concentration-dependent inhibition of PDGF-induced mitogenesis as determined by [ 3 H]thymidine incorporation or cell number. The IC 50 for T was approximately 5 μM. The inhibitory effect of terbinafine persisted in the presence of 0.4-8.0 μg/ml cholesterol or 130 μg/ml mevalonate. Administration of T to rats for 2 d before and 14 d after balloon catheter carotid injury resulted in a 40% decrease in lesion area. These observations indicate that T is both a potent in vitro antagonist of the smooth muscle cell mitogenic response to PDGF and an effective, well-tolerated, orally active inhibitor of myointimal proliferation in vivo

  14. Terbinafine: effects on platelet-derived growth factor-stimulated smooth muscle cells in vitro and myointimal proliferation in vivo

    Energy Technology Data Exchange (ETDEWEB)

    McCarthy, L.; Van Halen, R.G.; St. Denny, I.H.; Glinka, K.G.; Handley, D.A.; Stuetz, A.; Nemecek, G.M.

    1987-05-01

    Terbinafine (T; (E)-N-(6,6-dimethyl-2-hepten-4-ynyl)-N-methyl-1-naphthalenemethanamine), an antimycotic agent with antimitogenic activity in fibroblasts, was examined for its effects on platelet-derived growth factor (PDGF)-stimulated aortic smooth muscle cell DNA synthesis in vitro and myointimal proliferation in vivo. Exposure of smooth muscle cells to 1-25 ..mu..M T resulted in a concentration-dependent inhibition of PDGF-induced mitogenesis as determined by (/sup 3/H)thymidine incorporation or cell number. The IC/sub 50/ for T was approximately 5 ..mu..M. The inhibitory effect of terbinafine persisted in the presence of 0.4-8.0 ..mu..g/ml cholesterol or 130 ..mu..g/ml mevalonate. Administration of T to rats for 2 d before and 14 d after balloon catheter carotid injury resulted in a 40% decrease in lesion area. These observations indicate that T is both a potent in vitro antagonist of the smooth muscle cell mitogenic response to PDGF and an effective, well-tolerated, orally active inhibitor of myointimal proliferation in vivo.

  15. Cerebral cortex activation mapping upon electrical muscle stimulation by 32-channel time-domain functional near-infrared spectroscopy.

    Science.gov (United States)

    Re, Rebecca; Muthalib, Makii; Contini, Davide; Zucchelli, Lucia; Torricelli, Alessandro; Spinelli, Lorenzo; Caffini, Matteo; Ferrari, Marco; Quaresima, Valentina; Perrey, Stephane; Kerr, Graham

    2013-01-01

    The application of different EMS current thresholds on muscle activates not only the muscle but also peripheral sensory axons that send proprioceptive and pain signals to the cerebral cortex. A 32-channel time-domain fNIRS instrument was employed to map regional cortical activities under varied EMS current intensities applied on the right wrist extensor muscle. Eight healthy volunteers underwent four EMS at different current thresholds based on their individual maximal tolerated intensity (MTI), i.e., 10 % < 50 % < 100 % < over 100 % MTI. Time courses of the absolute oxygenated and deoxygenated hemoglobin concentrations primarily over the bilateral sensorimotor cortical (SMC) regions were extrapolated, and cortical activation maps were determined by general linear model using the NIRS-SPM software. The stimulation-induced wrist extension paradigm significantly increased activation of the contralateral SMC region according to the EMS intensities, while the ipsilateral SMC region showed no significant changes. This could be due in part to a nociceptive response to the higher EMS current intensities and result also from increased sensorimotor integration in these cortical regions.

  16. Effect of Neuromuscular Electrical Muscle Stimulation on Energy Expenditure in Healthy Adults

    Directory of Open Access Journals (Sweden)

    Ya-Ju Chang

    2011-02-01

    Full Text Available Weight loss/weight control is a major concern in prevention of cardiovascular disease and the realm of health promotion. The primary aim of this study was to investigate the effect of neuromuscular electrical stimulation (NMES at different intensities on energy expenditure (oxygen and calories in healthy adults. The secondary aim was to develop a generalized linear regression (GEE model to predict the increase of energy expenditure facilitated by NMES and identify factors (NMES stimulation intensity level, age, body mass index, weight, body fat percentage, waist/hip ratio, and gender associated with this NMES-induced increase of energy expenditure. Forty sedentary healthy adults (18 males and 22 females participated. NMES was given at the following stimulation intensities for 10 minutes each: sensory level (E1, motor threshold (E2, and maximal intensity comfortably tolerated (E3. Cardiopulmonary gas exchange was evaluated during rest, NMES, and recovery stage. The results revealed that NMES at E2 and E3 significantly increased energy expenditure and the energy expenditure at recovery stage was still significantly higher than baseline. The GEE model demonstrated that a linear dose-response relationship existed between the stimulation intensity and the increase of energy expenditure. No subject’s demographic or anthropometric characteristics tested were significantly associated with the increase of energy expenditure. This study suggested NMES may be used to serve as an additional intervention for weight loss programs. Future studies to develop electrical stimulators or stimulation electrodes to maximize the comfort of NMES are recommended.

  17. Effect of neuromuscular electrical muscle stimulation on energy expenditure in healthy adults.

    Science.gov (United States)

    Hsu, Miao-Ju; Wei, Shun-Hwa; Chang, Ya-Ju

    2011-01-01

    Weight loss/weight control is a major concern in prevention of cardiovascular disease and the realm of health promotion. The primary aim of this study was to investigate the effect of neuromuscular electrical stimulation (NMES) at different intensities on energy expenditure (oxygen and calories) in healthy adults. The secondary aim was to develop a generalized linear regression (GEE) model to predict the increase of energy expenditure facilitated by NMES and identify factors (NMES stimulation intensity level, age, body mass index, weight, body fat percentage, waist/hip ratio, and gender) associated with this NMES-induced increase of energy expenditure. Forty sedentary healthy adults (18 males and 22 females) participated. NMES was given at the following stimulation intensities for 10 minutes each: sensory level (E1), motor threshold (E2), and maximal intensity comfortably tolerated (E3). Cardiopulmonary gas exchange was evaluated during rest, NMES, and recovery stage. The results revealed that NMES at E2 and E3 significantly increased energy expenditure and the energy expenditure at recovery stage was still significantly higher than baseline. The GEE model demonstrated that a linear dose-response relationship existed between the stimulation intensity and the increase of energy expenditure. No subject's demographic or anthropometric characteristics tested were significantly associated with the increase of energy expenditure. This study suggested NMES may be used to serve as an additional intervention for weight loss programs. Future studies to develop electrical stimulators or stimulation electrodes to maximize the comfort of NMES are recommended.

  18. Insulin stimulation regulates AS160 and TBC1D1 phosphorylation sites in human skeletal muscle

    DEFF Research Database (Denmark)

    Middelbeek, R J W; Chambers, M A; Tantiwong, P

    2013-01-01

    Individuals with obesity and type 2 diabetes (T2D) are typically insulin resistant, exhibiting impaired skeletal muscle glucose uptake. Animal and cell culture experiments have shown that site-specific phosphorylation of the Rab-GTPase-activating proteins AS160 and TBC1D1 is critical for GLUT4 tr...

  19. Prior AICAR stimulation increases insulin sensitivity in mouse skeletal muscle in an AMPK-dependent manner

    DEFF Research Database (Denmark)

    Kjøbsted, Rasmus; Treebak, Jonas Thue; Fentz, Joachim

    2015-01-01

    Acute exercise increases glucose uptake in skeletal muscle by an insulin-independent mechanism. In the period after exercise insulin sensitivity to increase glucose uptake is enhanced. The molecular mechanisms underpinning this phenomenon are poorly understood, but appear to involve an increased ...

  20. Force Per Active Area and Muscle Injury during Electrically Stimulated Contractions

    OpenAIRE

    BLACK, CHRISTOPHER D.; MCCULLY, KEVIN K.

    2008-01-01

    Multiple mechanical factors have been implicated in the initiation of exercise-induced muscle injury. Although high absolute force levels are associated with greater injury, the importance of high force per active area independent of absolute force remains to be determined, especially in humans.

  1. Endurance exercise differentially stimulates heart and axial muscle development in zebrafish (Danio rerio)

    NARCIS (Netherlands)

    Meulen, T. van der; Schipper, H.; Boogaart, J.G. van den; Huising, M.O.; Kranenbarg, S.; Leeuwen, J.L. van

    2006-01-01

    Mechanical load is an important factor in the differentiation of cells and tissues. To investigate the effects of increased mechanical load on development of muscle and bone, zebrafish were subjected to endurance swim training for 6 h/day for 10 wk starting at 14 days after fertilization. During the

  2. Effects of Constant and Doublet Frequency Electrical Stimulation Patterns on Force Production of Knee Extensor Muscles.

    Directory of Open Access Journals (Sweden)

    Carole Cometti

    Full Text Available This study compared knee extensors' neuromuscular fatigue in response to two 30-minute stimulation patterns: constant frequency train (CFT and doublet frequency train (DFT. Fifteen men underwent two separate sessions corresponding to each pattern. Measurements included torque evoked by each contraction and maximal voluntary contractions (MVC measured before and immediately after the stimulation sessions. In addition, activation level and torque evoked during doublets (Pd and tetanic contractions at 80-Hz (P80 and 20-Hz (P20 were determined in six subjects. Results indicated greater mean torque during the DFT stimulation session as compared with CFT. But, no difference was obtained between the two stimulation patterns for MVC and evoked torque decreases. Measurements conducted in the subgroup depicted a significant reduction of Pd, P20 and P80. Statistical analyses also revealed bigger P20 immediate reductions after CFT than after DFT. We concluded that DFT could be a useful stimulation pattern to produce and maintain greater force with quite similar fatigue than CFT.

  3. Akt and Rac1 signalling are jointly required for insulin-stimulated glucose uptake in skeletal muscle and downregulated in insulin resistance

    DEFF Research Database (Denmark)

    Sylow, Lykke; Kleinert, Maximilian; Pehmøller, Christian

    2014-01-01

    Skeletal muscle plays a major role in regulating whole body glucose metabolism. Akt and Rac1 are important regulators of insulin-stimulated glucose uptake in skeletal muscle. However the relative role of each pathway and how they interact is not understood. Here we delineate how Akt and Rac1...... pathways signal to increase glucose transport independently of each other and are simultaneously downregulated in insulin resistant muscle. Pharmacological inhibition of Rac1 and Akt signalling was used to determine the contribution of each pathway to insulin-stimulated glucose uptake in mouse muscles....... The actin filament-depolymerizing agent LatrunculinB was combined with pharmacological inhibition of Rac1 or Akt, to examine whether either pathway mediates its effect via the actin cytoskeleton. Akt and Rac1 signalling were investigated under each condition, as well as upon Akt2 knockout and in ob/ob mice...

  4. Effects of electrical stimulation-induced gluteal versus gluteal and hamstring muscles activation on sitting pressure distribution in persons with a spinal cord injury.

    Science.gov (United States)

    Smit, C A J; Haverkamp, G L G; de Groot, S; Stolwijk-Swuste, J M; Janssen, T W J

    2012-08-01

    Ten participants underwent two electrical stimulation (ES) protocols applied using a custom-made electrode garment with built-in electrodes. Interface pressure was measured using a force-sensitive area. In one protocol, both the gluteal and hamstring (g+h) muscles were activated, in the other gluteal (g) muscles only. To study and compare the effects of electrically induced activation of g+h muscles versus g muscles only on sitting pressure distribution in individuals with a spinal cord injury (SCI). Ischial tuberosities interface pressure (ITs pressure) and pressure gradient. In all participants, both protocols of g and g+h ES-induced activation caused a significant decrease in IT pressure. IT pressure after g+h muscles activation was reduced significantly by 34.5% compared with rest pressure, whereas a significant reduction of 10.2% after activation of g muscles only was found. Pressure gradient reduced significantly only after stimulation of g+h muscles (49.3%). g+h muscles activation showed a decrease in pressure relief (Δ IT) over time compared with g muscles only. Both protocols of surface ES-induced of g and g+h activation gave pressure relief from the ITs. Activation of both g+h muscles in SCI resulted in better IT pressure reduction in sitting individuals with a SCI than activation of g muscles only. ES might be a promising method in preventing pressure ulcers (PUs) on the ITs in people with SCI. Further research needs to show which pressure reduction is sufficient in preventing PUs.

  5. Muscle fatigue resistance during stimulated contractions is reduced in young male smokers.

    NARCIS (Netherlands)

    Morse, C.I.; Wust, R.C.I.; Jones, D.A.; de Haan, A.; Degens, H.

    2007-01-01

    Aim: To determine whether muscle function is compromised in healthy smokers in comparison with activity-matched non-smokers. Methods: Nine male smokers (aged 22.2 ± 2.5 years: mean ± SD) with a smoking history of 2.5 ± 3.1 pack years, and ten male control participants (25.4 ± 2.9 years) matched for

  6. Macrophage secretory products selectively stimulate dermatan sulfate proteoglycan production in cultured arterial smooth muscle cells

    International Nuclear Information System (INIS)

    Edwards, I.J.; Wagner, W.D.; Owens, R.T.

    1990-01-01

    Arterial dermatan sulfate proteoglycan has been shown to increase with atherosclerosis progression, but factors responsible for this increase are unknown. To test the hypothesis that smooth muscle cell proteoglycan synthesis may be modified by macrophage products, pigeon arterial smooth muscle cells were exposed to the media of either cholesteryl ester-loaded pigeon peritoneal macrophages or a macrophage cell line P388D1. Proteoglycans radiolabeled with [35S]sulfate and [3H]serine were isolated from culture media and smooth muscle cells and purified following precipitation with 1-hexadecylpyridinium chloride and chromatography. Increasing concentrations of macrophage-conditioned media were associated with a dose-response increase in [35S]sulfate incorporation into secreted proteoglycans, but there was no change in cell-associated proteoglycans. Incorporation of [3H]serine into total proteoglycan core proteins was not significantly different (5.2 X 10(5) dpm and 5.5 X 10(5) disintegrations per minute (dpm) in control and conditioned media-treated cultures, respectively), but selective effects were observed on individual proteoglycan types. Twofold increases in dermatan sulfate proteoglycan and limited degradation of chondroitin sulfate proteoglycan were apparent based on core proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Immunoinhibition studies indicated that interleukin-1 was involved in the modulation of proteoglycan synthesis by macrophage-conditioned media. These data provide support for the role of macrophages in alteration of the matrix proteoglycans synthesized by smooth muscle cells and provide a mechanism to account for the reported increased dermatan sulfate/chondroitin sulfate ratios in the developing atherosclerotic lesion

  7. Myofibrillar proteolysis in response to voluntary or electrically stimulated muscle contractions in humans

    DEFF Research Database (Denmark)

    Hansen, M; Trappe, T; Crameri, R M

    2008-01-01

    Knowledge about the effects of exercise on myofibrillar protein breakdown in human subjects is limited. Our purpose was to measure the changes in the degradation of myofibrillar proteins in response to different ways of eliciting muscle contractions using the local interstitial 3-methyl-histidine......Knowledge about the effects of exercise on myofibrillar protein breakdown in human subjects is limited. Our purpose was to measure the changes in the degradation of myofibrillar proteins in response to different ways of eliciting muscle contractions using the local interstitial 3-methyl....... Only after ES did the histochemical stainings show significant disruption of cytoskeletal proteins. Furthermore, intracellular disruption and destroyed Z-lines were markedly more pronounced in ES vs VOL. In conclusion, the local level of interstitial 3-MH in the skeletal muscle was significantly...... enhanced after ES compared with VOL immediately after exercise, while the level of 3-MH did not change in the post-exercise period after VOL. These results indicate that the local myofibrillar breakdown is accelerated after ES associated with severe myofiber damage....

  8. A nerve stimulation method to selectively recruit smaller motor-units in rat skeletal muscle

    NARCIS (Netherlands)

    van Bolhuis, A.I.; Holsheimer, J.; Savelsberg, H.H.C.M.

    2001-01-01

    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

  9. 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...

  10. Studies of gene expression and activity of hexokinase, phosphofructokinase and glycogen synthase in human skeletal muscle in states of altered insulin-stimulated glucose metabolism

    DEFF Research Database (Denmark)

    Vestergaard, H

    1999-01-01

    been reported to increase the basal concentration of muscle GS mRNA in NIDDM patients to a level similar to that seen in control subjects although insulin-stimulated glucose disposal rates remain reduced in NIDDM patients. In the insulin resistant states examined so far, basal and insulin-stimulated......When whole body insulin-stimulated glucose disposal rate is measured in man applying the euglycaemic, hyperinsulinaemic clamp technique it has been shown that approximately 75% of glucose is taken up by skeletal muscle. After the initial transport step, glucose is rapidly phosphorylated to glucose...... critical roles in glucose oxidation/glycolysis and glucose storage, respectively. Glucose transporters and glycogen synthase activities are directly and acutely stimulated by insulin whereas the activities of hexokinases and phosphofructokinase may primarily be allosterically regulated. The aim...

  11. Reduced malonyl-CoA content in recovery from exercise correlates with improved insulin-stimulated glucose uptake in human skeletal muscle

    DEFF Research Database (Denmark)

    Frøsig, Christian; Roepstorff, Carsten; Brandt, Nina

    2009-01-01

    This study evaluated whether improved insulin-stimulated glucose uptake in recovery from acute exercise coincides with reduced malonyl-CoA (MCoA) content in human muscle. Furthermore, we investigated whether a high-fat diet [65 energy-% (Fat)] would alter the content of MCoA and insulin action...... to be compromised, although to a minor extent, by the Fat diet. Collectively, this study indicates that reduced muscle MCoA content in recovery from exercise may be part of the adaptive response leading to improved insulin action on glucose uptake after exercise in human muscle....

  12. Rac1 and AMPK Account for the Majority of Muscle Glucose Uptake Stimulated by Ex Vivo Contraction but Not In Vivo Exercise

    DEFF Research Database (Denmark)

    Sylow, Lykke; Møller, Lisbeth; Kleinert, Maximilian

    2017-01-01

    , but whether those two signaling pathways jointly account for the entire signal to glucose transport is unknown. We therefore studied the ability of contraction and exercise to stimulate glucose transport in isolated muscles with AMPK loss of function combined with either pharmacological inhibition or genetic...... uptake in vivo was only partially reduced by Rac1 mKO with no additive effect of a2KD. It is concluded that Rac1 and AMPK together account for almost the entire ex vivo contraction response in muscle glucose transport, whereas only Rac1, but not a2 AMPK, regulates muscle glucose uptake during submaximal...

  13. β-actin shows limited mobility and is only required for supraphysiological insulin-stimulated glucose transport in young adult soleus muscle

    DEFF Research Database (Denmark)

    Madsen, Agnete Louise Bjerregaard; Knudsen, Jonas Roland; Henriquez-Olguin, Carlos

    2018-01-01

    Studies in skeletal muscle cell cultures suggest that the cortical actin cytoskeleton is a major requirement for insulin-stimulated glucose transport, implicating the β-actin isoform which, in many cell types, is the main actin isoform. However, it is not clear that β-actin plays such a role...... in mature mouse muscle under the majority of the tested conditions. Thus, our work reveals fundamental differences in the role of the cortical β-actin cytoskeleton in mature muscle compared to cell culture....

  14. Contraction-stimulated glucose transport in muscle is controlled by AMPK and mechanical stress but not sarcoplasmatic reticulum Ca2+ release

    Directory of Open Access Journals (Sweden)

    Thomas E. Jensen

    2014-10-01

    Full Text Available Understanding how muscle contraction orchestrates insulin-independent muscle glucose transport may enable development of hyperglycemia-treating drugs. The prevailing concept implicates Ca2+ as a key feed forward regulator of glucose transport with secondary fine-tuning by metabolic feedback signals through proteins such as AMPK. Here, we demonstrate in incubated mouse muscle that Ca2+ release is neither sufficient nor strictly necessary to increase glucose transport. Rather, the glucose transport response is associated with metabolic feedback signals through AMPK, and mechanical stress-activated signals. Furthermore, artificial stimulation of AMPK combined with passive stretch of muscle is additive and sufficient to elicit the full contraction glucose transport response. These results suggest that ATP-turnover and mechanical stress feedback are sufficient to fully increase glucose transport during muscle contraction, and call for a major reconsideration of the established Ca2+ centric paradigm.

  15. Mechanisms for greater insulin-stimulated glucose uptake in normal and insulin-resistant skeletal muscle after acute exercise

    Science.gov (United States)

    2015-01-01

    Enhanced skeletal muscle and whole body insulin sensitivity can persist for up to 24–48 h after one exercise session. This review focuses on potential mechanisms for greater postexercise and insulin-stimulated glucose uptake (ISGU) by muscle in individuals with normal or reduced insulin sensitivity. A model is proposed for the processes underlying this improvement; i.e., triggers initiate events that activate subsequent memory elements, which store information that is relayed to mediators, which translate memory into action by controlling an end effector that directly executes increased insulin-stimulated glucose transport. Several candidates are potential triggers or memory elements, but none have been conclusively verified. Regarding potential mediators in both normal and insulin-resistant individuals, elevated postexercise ISGU with a physiological insulin dose coincides with greater Akt substrate of 160 kDa (AS160) phosphorylation without improved proximal insulin signaling at steps from insulin receptor binding to Akt activity. Causality remains to be established between greater AS160 phosphorylation and improved ISGU. The end effector for normal individuals is increased GLUT4 translocation, but this remains untested for insulin-resistant individuals postexercise. Following exercise, insulin-resistant individuals can attain ISGU values similar to nonexercising healthy controls, but after a comparable exercise protocol performed by both groups, ISGU for the insulin-resistant group has been consistently reported to be below postexercise values for the healthy group. Further research is required to fully understand the mechanisms underlying the improved postexercise ISGU in individuals with normal or subnormal insulin sensitivity and to explain the disparity between these groups after similar exercise. PMID:26487009

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

    Energy Technology Data Exchange (ETDEWEB)

    Everts, M.E.; Clausen, T. (Aarhus Univ. (Denmark))

    1988-11-01

    The effects of hypothyroidism and 3,5,3{prime}-triiodothyronine (T{sub 3}) treatment on passive Na{sup +}-K{sup +} fluxes and Na{sup +}-K{sup +} pump concentration were investigated in isolated rat muscle. Within 12 h after a single dose of T{sub 3} (20 {mu}g/100 g body wt), K{sup +} 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{sup +} influx but no significant increase in ({sup 3}H)ouabain binding site concentration. After 3 days of T{sub 3} treatment, the stimulating effect on K{sup +} efflux and Na{sup +} influx in soleus reached a plateau {approximately}80 and 40% above control levels, respectively, whereas the maximum increase in ({sup 3}H)ouabain binding site concentration (103%) was only fully developed after 8 days. Hypothyroidism decreased {sup 86}Rb efflux by 30%. The efflux of K{sup +} and the influx of Na{sup +} per contraction (both {approximately}7 nmol/g wet wt) as well as the net loss of K{sup +} induced by electrical stimulation were unaffected by T{sub 3} treatment. The rise in resting K{sup +} efflux after 12-24 h of T{sub 3} treatment could be partly blocked by dantrolene or trifluoroperazine, indicating that an increase in the cytoplasmic Ca{sup 2+} concentration may contribute to the early rise in K{sup +} efflux. It is concluded that the early rise in the resting passive leaks of Na{sup +} and K{sup +} induced by T{sub 3} is a major driving force for Na{sup +}-K{sup +} pump synthesis.

  17. Stimulation of muscle protein synthesis by whey and caseinate ingestion after resistance exercise in elderly individuals

    DEFF Research Database (Denmark)

    Dideriksen, K J; Reitelseder, S; Petersen, S G

    2011-01-01

    Sarcopenia is a well-known phenomenon in elderly individuals and resistance exercise together with sufficient amino acid (AA) availability has proved to be a counteractive implement. However, the source of AA and supplement timing require further investigation. The objective was to compare muscle...... protein synthesis (MPS) to intakes of whey and caseinate after heavy resistance exercise in healthy elderly individuals, and, furthermore, to compare the timing effect of caseinate intake. Twenty-four elderly men and women (mean ± SEM; 68 ± 1 years) were randomized to one of four groups: caseinate intake...

  18. 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

  19. A estimulação russa no fortalecimento da musculatura abdominal Russian stimulation in strengthening abdominal muscle

    Directory of Open Access Journals (Sweden)

    Evelyne Patrícia Fernandes Lima

    2012-06-01

    Full Text Available INTRODUÇÃO - A flacidez muscular surge com maior frequência nas mulheres, o que causa fator ruim para a estética corporal. OBJETIVO - Analisar os resultados da corrente russa no fortalecimento da musculatura abdominal. MÉTODOS - Revisão bibliográfica com base nas publicações acessíveis pelas seguintes bases de dados: Medline/Pubmed, Scielo, Lilacs com cruzamento dos descritores corrente russa, flacidez, abdômen. O uso da eletroestimulação age tanto sobre as fibras brancas, que respondem pela velocidade, como também sobre as fibras vermelhas dado à sua sustentação, e ainda sobre as fibras intermediárias. CONCLUSÃO - Os dados publicados mostram a satisfação e êxito do tratamento, enfatizando que a corrente russa favorece o aumento da hipertrofia e força muscular.INTRODUCTION - Muscle weakness appears most often in women, the factor that causes bad esthetics. OBJECTIVE - To analyze the results of the Russian current strengthening the abdominal muscles. METHODS - Literature review based on publications available in the following databases: Medline / Pubmed, Scielo, Lilacs with crossing headings Russian current, sagging, abdomen. The use of electrical stimulation acts both on the white fibers, which account for the speed, but also on the red fibers given their support, and on intermediate fibers. CONCLUSION - The data published show the satisfaction and success of treatment, emphasizing that the Russian current promotes increase of muscle strength and hypertrophy.

  20. α-Trinositol inhibits FGF-stimulated growth of smooth muscle and breast cancer cells

    International Nuclear Information System (INIS)

    Siren, Matti J.; Vainiomaeki, Maija; Vaeaenaenen, Kalervo; Haerkoenen, Pirkko

    2004-01-01

    α-Trinositol (D-myo-inositol-1,2,6-trisphosphate), an isomer of the intracellular messenger IP 3 , has been studied for its anti-inflammatory and other effects in animal experiments and in human. The mechanisms of action remain unknown. Several human pathologies are associated with uncontrolled production of fibroblast growth factors (FGFs). FGF-2 induces vascular smooth muscle cell proliferation, which contributes to restenosis after coronary balloon angioplasty. The expression of several FGFs is also increased in tumors. We studied the effects of the water- and lipid-soluble derivatives of α-trinositol on the FGF-2- and/or FGF-8-induced proliferation of human pulmonary artery smooth muscle cells (HPASMC) and S115 mouse breast cancer cells. α-Trinositol decreased the FGF-mediated proliferation of HPASMC and S115 cells. Membrane permeability did not seem obligatory since the lipid-soluble form of α-trinositol was less effective than the water-soluble derivative. These results suggest a new biological function for certain phosphoinositides in the modulation of FGF-regulated processes

  1. The Oligo Fucoidan Inhibits Platelet-Derived Growth Factor-Stimulated Proliferation of Airway Smooth Muscle Cells

    Directory of Open Access Journals (Sweden)

    Chao-Huei Yang

    2016-01-01

    Full Text Available In the pathogenesis of asthma, the proliferation of airway smooth muscle cells (ASMCs is a key factor in airway remodeling and causes airway narrowing. In addition, ASMCs are also the effector cells of airway inflammation. Fucoidan extracted from marine brown algae polysaccharides has antiviral, antioxidant, antimicrobial, anticlotting, and anticancer properties; however, its effectiveness for asthma has not been elucidated thus far. Platelet-derived growth factor (PDGF-treated primary ASMCs were cultured with or without oligo-fucoidan (100, 500, or 1000 µg/mL to evaluate its effects on cell proliferation, cell cycle, apoptosis, and Akt, ERK1/2 signaling pathway. We found that PDGF (40 ng/mL increased the proliferation of ASMCs by 2.5-fold after 48 h (p < 0.05. Oligo-fucoidan reduced the proliferation of PDGF-stimulated ASMCs by 75%–99% after 48 h (p < 0.05 and induced G1/G0 cell cycle arrest, but did not induce apoptosis. Further, oligo-fucoidan supplementation reduced PDGF-stimulated extracellular signal-regulated kinase (ERK1/2, Akt, and nuclear factor (NF-κB phosphorylation. Taken together, oligo-fucoidan supplementation might reduce proliferation of PDGF-treated ASMCs through the suppression of ERK1/2 and Akt phosphorylation and NF-κB activation. The results provide basis for future animal experiments and human trials.

  2. Voluntary wheel running selectively augments insulin-stimulated vasodilation in arterioles from white skeletal muscle of insulin-resistant rats.

    Science.gov (United States)

    Mikus, Catherine R; Roseguini, Bruno T; Uptergrove, Grace M; Morris, E Matthew; Rector, Randy Scott; Libla, Jessica L; Oberlin, Douglas J; Borengasser, Sarah J; Taylor, Angelina M; Ibdah, Jamal A; Laughlin, Maurice Harold; Thyfault, John P

    2012-11-01

    Exercise (RUN) prevents declines in insulin-mediated vasodilation, an important component of insulin-mediated glucose disposal, in rats prone to obesity and insulin resistance. Determine whether RUN (1) improves insulin-stimulated vasodilation after insulin resistance has been established, and (2) differentially affects arterioles from red and white muscle. Insulin signaling and vasoreactivity to insulin (1-1000 μIU/mL) were assessed in 2A from the Gw and Gr of SED OLETF rats at 12 and 20 weeks of age (SED12, SED20) and those undergoing RUN (RUN20) or caloric restriction (CR20; to match body weight of RUN) from 12 to 20 weeks. Glucose and insulin responses to i.p. glucose were reduced in RUN20, elevated in SED20 (p RUN20 (p RUN selectively improved insulin-mediated vasodilation in Gw 2As, in part through attenuated ET-1 sensitivity/production, an adaptation that was independent of changes in adiposity and may contribute to enhanced insulin-stimulated glucose disposal. © 2012 John Wiley & Sons Ltd.

  3. α-MSH stimulates glucose uptake in mouse muscle and phosphorylates Rab-GTPase-activating protein TBC1D1 independently of AMPK

    DEFF Research Database (Denmark)

    Møller, Cathrine Laustrup; Kjøbsted, Rasmus; Enriori, Pablo J

    2016-01-01

    The melanocortin system includes five G-protein coupled receptors (family A) defined as MC1R-MC5R, which are stimulated by endogenous agonists derived from proopiomelanocortin (POMC). The melanocortin system has been intensely studied for its central actions in body weight and energy expenditure...... pathway involved in α-MSH-stimulated glucose uptake in differentiated L6 myotubes and mouse muscle explants. In order to examine the involvement of AMPK, we investigate -MSH stimulation in both wild type and AMPK deficient mice. We found that -MSH significantly induces phosphorylation of TBC1 domain (TBC1...

  4. The effect of exercise and beta2-adrenergic stimulation on glutathionylation and function of the Na,K-ATPase in human skeletal muscle

    DEFF Research Database (Denmark)

    Juel, Carsten; Hostrup, Morten; Bangsbo, Jens

    2015-01-01

    ) on Na,K-ATPase activity. Ten male subjects performed three bouts of 4-min submaximal exercise followed by intense exercise to exhaustion with and without beta2-adrenergic stimulation with terbutaline. Muscle biopsies were obtained from m. vastus lateralis at rest (Control samples) and at exhaustion....... In vitro glutathionylation reduced (P basal glutathionylation in Control samples and no further glutathionylation with exercise and beta......2-adrenergic stimulation. Immunoprecipitation with an anti-GSH antibody and subsequent immunodetection with β1 antibodies showed approximately 20% glutathionylation in Control samples and further glutathionylation after exercise (to 32%) and beta2-adrenergic stimulation (to 38%, P

  5. The Use of Functional Electrical Stimulation on the Upper Limb and Interscapular Muscles of Patients with Stroke for the Improvement of Reaching Movements: A Feasibility Study

    Directory of Open Access Journals (Sweden)

    Alicia Cuesta-Gómez

    2017-05-01

    Full Text Available IntroductionReaching movements in stroke patients are characterized by decreased amplitudes at the shoulder and elbow joints and greater displacements of the trunk, compared to healthy subjects. The importance of an appropriate and specific contraction of the interscapular and upper limb (UL muscles is crucial to achieving proper reaching movements. Functional electrical stimulation (FES is used to activate the paretic muscles using short-duration electrical pulses.ObjectiveTo evaluate whether the application of FES in the UL and interscapular muscles of stroke patients with motor impairments of the UL modifies patients’ reaching patterns, measured using instrumental movement analysis systems.DesignA cross-sectional study was carried out.SettingThe VICON Motion System® was used to conduct motion analysis.ParticipantsTwenty-one patients with chronic stroke.InterventionThe Compex® electric stimulator was used to provide muscle stimulation during two conditions: a placebo condition and a FES condition.Main outcome measuresWe analyzed the joint kinematics (trunk, shoulder, and elbow from the starting position until the affected hand reached the glass.ResultsParticipants receiving FES carried out the movement with less trunk flexion, while shoulder flexion elbow extension was increased, compared to placebo conditions.ConclusionThe application of FES to the UL and interscapular muscles of stroke patients with motor impairment of the UL has improved reaching movements.

  6. Prolonged electrical stimulation-induced gluteal and hamstring muscle activation and sitting pressure in spinal cord injury: Effect of duty cycle

    NARCIS (Netherlands)

    MSc Karin J.A. Legemate; MD Christof A. J. Smit; MSc Anja de Koning; PhD Sonja de Groot; MD, PhD Janneke M. Stolwijk-Swuste; PhD Thomas W.H. Janssen

    2013-01-01

    Abstract—Pressure ulcers (PUs) are highly prevalent in people with spinal cord injury (SCI). Electrical stimulation (ES) activates muscles and might reduce risk factors. Our objectives were to study and compare the effects of two duty cycles during 3 h of ES-induced gluteal and hamstring activation

  7. Prolonged electrical stimulation-induced gluteal and hamstring muscle activation and sitting pressure in spinal cord injury : Effect of duty cycle

    NARCIS (Netherlands)

    Smit, Christof A. J.; Legemate, Karin J. A.; de Koning, Anja; de Groot, Sonja; Stolwijk-Swuste, Janneke M.; Janssen, Thomas W. J.

    2013-01-01

    Pressure ulcers (PUs) are highly prevalent in people with spinal cord injury (SCI). Electrical stimulation (ES) activates muscles and might reduce risk factors. Our objectives were to study and compare the effects of two duty cycles during 3 h of ES-induced gluteal and hamstring activation on

  8. Effects of electrical stimulation-induced gluteal versus gluteal and hamstring muscles activation on sitting pressure distribution in persons with a spinal cord injury

    NARCIS (Netherlands)

    Smit, C. A. J.; Haverkamp, G. L. G.; de Groot, S.; Stolwijk-Swuste, J. M.; Janssen, T. W. J.

    Study design: Ten participants underwent two electrical stimulation (ES) protocols applied using a custom-made electrode garment with built-in electrodes. Interface pressure was measured using a force-sensitive area. In one protocol, both the gluteal and hamstring (g+h) muscles were activated, in

  9. Gluteal blood flow and oxygenation during electrical stimulation-induced muscle activation versus pressure relief movements in wheelchair users with a spinal cord injury

    NARCIS (Netherlands)

    Smit, C. A. J.; Zwinkels, M.; van Dijk, T.; de Groot, S.; Stolwijk-Swuste, J. M.; Janssen, T. W. J.

    Background: Prolonged high ischial tuberosities pressure (IT pressure), decreased regional blood flow (BF) and oxygenation (%SO2) are risk factors for developing pressure ulcers (PUs) in patients with spinal cord injury (SCI). Electrical stimulation (ES)-induced gluteal and hamstring muscle

  10. 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...

  11. RhoA–Rho kinase and Platelet Activating Factor Stimulation of Ovine Fetal Pulmonary Vascular Smooth Muscle Cell Proliferation

    Science.gov (United States)

    Renteria, Lissette S.; Austin, Monique; Lazaro, Mariecon; Andrews, Mari Ashley; Lustina, Jennessee; Raj, J. Usha; Ibe, Basil O.

    2013-01-01

    Objectives Platelet Activating Factor (PAF) is produced by pulmonary vascular smooth muscle Cells (PVSMC). We studied effect of Rho kinase on PAF stimulation of PVSMC proliferation in an attempt to understand a role for RhoA/Rho kinase on PAF-induced ovine fetal pulmonary vascular remodeling. Our hypothesis is that PAF acts through Rho kinase, as one of its downstream signaling, to induce arterial (SMC-PA) and venous (SMC-PV) growth in the hypoxic lung environment of the fetus in utero. Materials and methods Rho kinase and MAPK effects on PAF receptor (PAFR)-mediated cell growth and PAFR expression were studied by DNA synthesis, Western and immunocytochemistry. Effects of constructs T19N and G14V on PAF-induced cell proliferation was also studied. Results Hypoxia increased PVSMC proliferation and the Rho kinase inhibitors, Y-27632 and Fasudil (HA-1077) as well as MAPK inhibitors PD 98059 and SB 203580 attenuated PAF stimulation of cell proliferation. RhoA T19N and G14V stimulated cell proliferation, but co-incubation with PAF did not affect proliferative effects of the constructs. PAFR protein expression was significantly down-regulated in both cell types by both Y-27632 and HA-1077 with comparable profiles. Also cells treated with Y-27632 showed less PAF receptor fluorescence with significant disruption of the cell morphology. Conclusions Our results show that Rho kinase nonspecifically modulates PAFR-mediated responses via a translational modification of PAFR protein and suggest that, in vivo, activation of Rho kinase by PAF may be one other pathway to sustain PAFR-mediated PVSMC growth. PMID:24033386

  12. RhoA-Rho kinase and platelet-activating factor stimulation of ovine foetal pulmonary vascular smooth muscle cell proliferation.

    Science.gov (United States)

    Renteria, L S; Austin, M; Lazaro, M; Andrews, M A; Lustina, J; Raj, J U; Ibe, B O

    2013-10-01

    Platelet-activating factor (PAF) is produced by pulmonary vascular smooth muscle cells (PVSMC). We studied effects of Rho kinase on PAF stimulation of PVSMC proliferation in an attempt to understand the role of RhoA/Rho kinase on PAF-induced ovine foetal pulmonary vascular remodelling. Our hypothesis is that PAF acts through Rho kinase, as one of its downstream signals, to induce arterial (SMC-PA) and venous (SMC-PV) cell proliferation in the hypoxic lung environment of the foetus, in utero. Rho kinase and MAPK effects on PAF receptor (PAFR)-mediated cell population expansion, and PAFR expression, were studied by DNA synthesis, western blot analysis and immunocytochemistry. Effects of constructs T19N and G14V on PAF-induced cell proliferation were also investigated. Hypoxia increased PVSMC proliferation and Rho kinase inhibitors, Y-27632 and Fasudil (HA-1077) as well as MAPK inhibitors PD 98059 and SB 203580 attenuated PAF stimulation of cell proliferation. RhoA T19N and G14V stimulated cell proliferation, but co-incubation with PAF did not affect proliferative effects of the constructs. PAFR protein expression was significantly downregulated in both cell types by both Y-27632 and HA-1077, with comparable profiles. Also, cells treated with Y-27632 had less PAF receptor fluorescence with significant disruption of cell morphology. Our results show that Rho kinase non-specifically modulated PAFR-mediated responses by a translational modification of PAFR protein, and suggest that, in vivo, activation of Rho kinase by PAF may be a further pathway to sustain PAFR-mediated PVSMC proliferation. © 2013 John Wiley & Sons Ltd.

  13. Stimulation of muscle protein synthesis by whey and caseinate ingestion after resistance exercise in elderly individuals

    DEFF Research Database (Denmark)

    Dideriksen, K J; Reitelseder, S; Petersen, S G

    2011-01-01

    Sarcopenia is a well-known phenomenon in elderly individuals and resistance exercise together with sufficient amino acid (AA) availability has proved to be a counteractive implement. However, the source of AA and supplement timing require further investigation. The objective was to compare muscle...... protein synthesis (MPS) to intakes of whey and caseinate after heavy resistance exercise in healthy elderly individuals, and, furthermore, to compare the timing effect of caseinate intake. Twenty-four elderly men and women (mean ± SEM; 68 ± 1 years) were randomized to one of four groups: caseinate intake...... and caseinate feeding immediately after heavy resistance exercise in elderly individuals, and MPS is similar with caseinate ingestion before and after exercise....

  14. Effect of tendon vibration during wide-pulse neuromuscular electrical stimulation (NMES) on muscle force production in people with spinal cord injury (SCI).

    Science.gov (United States)

    Bochkezanian, Vanesa; Newton, Robert U; Trajano, Gabriel S; Vieira, Amilton; Pulverenti, Timothy S; Blazevich, Anthony J

    2018-02-13

    Neuromuscular electrical stimulation (NMES) is commonly used in skeletal muscles in people with spinal cord injury (SCI) with the aim of increasing muscle recruitment and thus muscle force production. NMES has been conventionally used in clinical practice as functional electrical stimulation (FES), using low levels of evoked force that cannot optimally stimulate muscular strength and mass improvements, and thus trigger musculoskeletal changes in paralysed muscles. The use of high intensity intermittent NMES training using wide-pulse width and moderate-intensity as a strength training tool could be a promising method to increase muscle force production in people with SCI. However, this type of protocol has not been clinically adopted because it may generate rapid muscle fatigue and thus prevent the performance of repeated high-intensity muscular contractions in paralysed muscles. Moreover, superimposing patellar tendon vibration onto the wide-pulse width NMES has been shown to elicit further increases in impulse or, at least, reduce the rate of fatigue in repeated contractions in able-bodied populations, but there is a lack of evidence to support this argument in people with SCI. Nine people with SCI received two NMES protocols with and without superimposing patellar tendon vibration on different days (i.e. STIM and STIM+vib), which consisted of repeated 30 Hz trains of 58 wide-pulse width (1000 μs) symmetric biphasic pulses (0.033-s inter-pulse interval; 2 s stimulation train; 2-s inter-train interval) being delivered to the dominant quadriceps femoris. Starting torque was 20% of maximal doublet-twitch torque and stimulations continued until torque declined to 50% of the starting torque. Total knee extensor impulse was calculated as the primary outcome variable. Total knee extensor impulse increased in four subjects when patellar tendon vibration was imposed (59.2 ± 15.8%) but decreased in five subjects (- 31.3 ± 25.7%). However, there were no

  15. Effects of transportation during the hot season, breed and electrical stimulation on histochemical and meat quality characteristics of goat longissimus muscle.

    Science.gov (United States)

    Kadim, Isam T; Mahgoub, Osman; Al-Marzooqi, Waleed; Khalaf, Samera; Al-Sinawi, Shadia S H; Al-Amri, Issa

    2010-06-01

    The effects of transportation and electrical stimulation (90 V) on physiological, histochemical and meat quality characteristics of two breeds of Omani goats were assessed. Twenty 1-year-old male goats from each breed (Batina and Dhofari) were divided into two groups: 3 h transported during the hot season (42 degrees C day time temperature) and non-transported. Animals were blood-sampled before loading and prior to slaughter. Electrical stimulation was applied 20 min postmortem to 50% randomly selected carcasses of both breeds. Temperature and pH decline of the Longissimus was monitored. Ultimate pH, shear force, sarcomere length, myofibrillar fragmentation index, expressed juice, cooking loss and colour were measured from samples of Longissimus dorsi muscles. Electrical stimulation and transportation had a significant effect on most biochemical and meat quality characteristics of Longissimus dorsi. The transported goats had higher plasma cortisol (P goats. Electrical stimulation resulted in a significantly (P Meat from transported goats had significantly higher pH, expressed juice and shear force, but contained significantly lower sarcomere length and L* values than non-transported goats. The proportion of the myosin ATPase staining did not change as a function of stimulation, transportation or breed. These results indicated that subjecting goats to transportation for 3 h under high ambient temperatures can generate major physiological and muscle metabolism responses. Electrical stimulation improved quality characteristics of meat from both groups. This indicates that electrical stimulation may reduce detrimental effects of transportation on meat quality of Omani goats.

  16. Experimental hyperthyroidism in rats increases the expression of the ubiquitin ligases atrogin-1 and MuRF1 and stimulates multiple proteolytic pathways in skeletal muscle.

    Science.gov (United States)

    O'Neal, Patrick; Alamdari, Nima; Smith, Ira; Poylin, Vitaliy; Menconi, Michael; Hasselgren, Per-Olof

    2009-11-01

    Muscle wasting is commonly seen in patients with hyperthyroidism and is mainly caused by stimulated muscle proteolysis. Loss of muscle mass in several catabolic conditions is associated with increased expression of the muscle-specific ubiquitin ligases atrogin-1 and MuRF1 but it is not known if atrogin-1 and MuRF1 are upregulated in hyperthyroidism. In addition, it is not known if thyroid hormone increases the activity of proteolytic mechanisms other than the ubiquitin-proteasome pathway. We tested the hypotheses that experimental hyperthyroidism in rats, induced by daily intraperitoneal injections of 100 microg/100 g body weight of triiodothyronine (T3), upregulates the expression of atrogin-1 and MuRF1 in skeletal muscle and stimulates lysosomal, including cathepsin L, calpain-, and caspase-3-dependent protein breakdown in addition to proteasome-dependent protein breakdown. Treatment of rats with T3 for 3 days resulted in an approximately twofold increase in atrogin-1 and MuRF1 mRNA levels. The same treatment increased proteasome-, cathepsin L-, and calpain-dependent proteolytic rates by approximately 40% but did not influence caspase-3-dependent proteolysis. The expression of atrogin-1 and MuRF1 remained elevated during a more prolonged period (7 days) of T3 treatment. The results provide support for a role of the ubiquitin-proteasome pathway in muscle wasting during hyperthyroidism and suggest that other proteolytic pathways as well may be activated in the hyperthyroid state. (c) 2009 Wiley-Liss, Inc.

  17. Hypertrophy Stimulation at the Onset of Type I Diabetes Maintains the Soleus but Not the EDL Muscle Mass in Wistar Rats

    Directory of Open Access Journals (Sweden)

    Marco A. S. Fortes

    2017-10-01

    Full Text Available Diabetes mellitus induces a reduction in skeletal muscle mass and strength. Strength training is prescribed as part of treatment since it improves glycemic control and promotes increase of skeletal muscle mass. The mechanisms involved in overload-induced muscle hypertrophy elicited at the establishment of the type I diabetic state was investigated in Wistar rats. The purpose was to examine whether the overload-induced hypertrophy can counteract the hypotrophy associated to the diabetic state. The experiments were performed in oxidative (soleus or glycolytic (EDL muscles. PI3K/Akt/mTOR protein synthesis pathway was evaluated 7 days after overload-induced hypertrophy of soleus and of EDL muscles. The mRNA expression of genes associated with different signaling pathways that control muscle hypertrophy was also evaluated: mechanotransduction (FAK, Wnt/β-catenin, myostatin, and follistatin. The soleus and EDL muscles when submitted to overload had similar hypertrophic responses in control and diabetic animals. The increase of absolute and specific twitch and tetanic forces had the same magnitude as muscle hypertrophic response. Hypertrophy of the EDL muscle from diabetic animals mostly involved mechanical loading-stimulated PI3K/Akt/mTOR pathway besides the reduced activation of AMP-activated protein kinase (AMPK and decrease of myostatin expression. Hypertrophy was more pronounced in the soleus muscle of diabetic animals due to a more potent activation of rpS6 and increased mRNA expression of insulin-like growth factor-1 (IGF-1, mechano-growth factor (MGF and follistatin, and decrease of myostatin, MuRF-1 and atrogin-1 contents. The signaling changes enabled the soleus muscle mass and force of the diabetic rats to reach the values of the control group.

  18. Hypertrophy Stimulation at the Onset of Type I Diabetes Maintains the Soleus but Not the EDL Muscle Mass in Wistar Rats

    Science.gov (United States)

    Fortes, Marco A. S.; Scervino, Maria V. M.; Marzuca-Nassr, Gabriel N.; Vitzel, Kaio F.; da Justa Pinheiro, Carlos H.; Curi, Rui

    2017-01-01

    Diabetes mellitus induces a reduction in skeletal muscle mass and strength. Strength training is prescribed as part of treatment since it improves glycemic control and promotes increase of skeletal muscle mass. The mechanisms involved in overload-induced muscle hypertrophy elicited at the establishment of the type I diabetic state was investigated in Wistar rats. The purpose was to examine whether the overload-induced hypertrophy can counteract the hypotrophy associated to the diabetic state. The experiments were performed in oxidative (soleus) or glycolytic (EDL) muscles. PI3K/Akt/mTOR protein synthesis pathway was evaluated 7 days after overload-induced hypertrophy of soleus and of EDL muscles. The mRNA expression of genes associated with different signaling pathways that control muscle hypertrophy was also evaluated: mechanotransduction (FAK), Wnt/β-catenin, myostatin, and follistatin. The soleus and EDL muscles when submitted to overload had similar hypertrophic responses in control and diabetic animals. The increase of absolute and specific twitch and tetanic forces had the same magnitude as muscle hypertrophic response. Hypertrophy of the EDL muscle from diabetic animals mostly involved mechanical loading-stimulated PI3K/Akt/mTOR pathway besides the reduced activation of AMP-activated protein kinase (AMPK) and decrease of myostatin expression. Hypertrophy was more pronounced in the soleus muscle of diabetic animals due to a more potent activation of rpS6 and increased mRNA expression of insulin-like growth factor-1 (IGF-1), mechano-growth factor (MGF) and follistatin, and decrease of myostatin, MuRF-1 and atrogin-1 contents. The signaling changes enabled the soleus muscle mass and force of the diabetic rats to reach the values of the control group. PMID:29123487

  19. Potent PPARγ Ligands from Swietenia macrophylla Are Capable of Stimulating Glucose Uptake in Muscle Cells

    Directory of Open Access Journals (Sweden)

    Wai Kwan Lau

    2015-12-01

    Full Text Available Numerous documented ethnopharmacological properties have been associated with Swietenia macrophylla (Meliaceae, with its seed extract reported to display anti-hypoglycemic activities in diabetic rats. In the present study, three compounds isolated from the seeds of S. macrophylla were tested on a modified ELISA binding assay and showed to possess PPARγ ligand activity. They were corresponded to PPARγ-mediated cellular response, stimulated adipocyte differentiation but produced lower amount of fat droplets compared to a conventional anti-diabetic agent, rosiglitazone. The up-regulation of adipocytes was followed by increased adipocyte-related gene expressions such as adiponectin, adipsin, and PPARγ. The S. macrophylla compounds also promoted cellular glucose uptake via the translocation of GLUT4 glucose transporter.

  20. RELM-β promotes human pulmonary artery smooth muscle cell proliferation via FAK-stimulated surviving

    International Nuclear Information System (INIS)

    Lin, Chunlong; Li, Xiaohui; Luo, Qiong; Yang, Hui; Li, Lun; Zhou, Qiong; Li, Yue; Tang, Hao; Wu, Lifu

    2017-01-01

    Resistin-like molecule-β (RELM-β), focal adhesion kinase (FAK), and survivin may be involved in the proliferation of cultured human pulmonary artery smooth muscle cells (HPAMSCs), which is involved in pulmonary hypertension. HPAMSCs were treated with human recombinant RELM-β (rhRELM-β). siRNAs against FAK and survivin were transfected into cultured HPASMCs. Expression of FAK and survivin were examined by RT-PCR and western blot. Immunofluorescence was used to localize FAK. Flow cytometry was used to examine cell cycle distribution and cell death. Compared to the control group, all rhRELM-β-treated groups demonstrated significant increases in the expression of FAK and survivin (P<0.05). rhRELM-β significantly increased the proportion of HPASMCs in the S phase and decreased the proportion in G0/G1. FAK siRNA down-regulated survivin expression while survivin siRNA did not affect FAK expression. FAK siRNA effectively inhibited FAK and survivin expression in RELM-β-treated HPASMCs and partially suppressed cell proliferation. RELM-β promoted HPASMC proliferation and upregulated FAK and survivin expression. In conclusion, results suggested that FAK is upstream of survivin in the signaling pathway mediating cell proliferation. FAK seems to be important in RELM-β-induced HPASMC proliferation, partially by upregulating survivin expression. - Highlights: • rhRELM-β increased the expression of FAK and survivin. • rhRELM-β increased the proportion of HPASMCs in the S phase. • FAK is upstream of survivin in the signaling pathway mediating cell proliferation. • FAK is important in RELM-β-induced HPASMC proliferation, partly via survivin.

  1. RELM-β promotes human pulmonary artery smooth muscle cell proliferation via FAK-stimulated surviving

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chunlong, E-mail: lclmd@sina.com; Li, Xiaohui; Luo, Qiong; Yang, Hui; Li, Lun; Zhou, Qiong; Li, Yue; Tang, Hao; Wu, Lifu

    2017-02-01

    Resistin-like molecule-β (RELM-β), focal adhesion kinase (FAK), and survivin may be involved in the proliferation of cultured human pulmonary artery smooth muscle cells (HPAMSCs), which is involved in pulmonary hypertension. HPAMSCs were treated with human recombinant RELM-β (rhRELM-β). siRNAs against FAK and survivin were transfected into cultured HPASMCs. Expression of FAK and survivin were examined by RT-PCR and western blot. Immunofluorescence was used to localize FAK. Flow cytometry was used to examine cell cycle distribution and cell death. Compared to the control group, all rhRELM-β-treated groups demonstrated significant increases in the expression of FAK and survivin (P<0.05). rhRELM-β significantly increased the proportion of HPASMCs in the S phase and decreased the proportion in G0/G1. FAK siRNA down-regulated survivin expression while survivin siRNA did not affect FAK expression. FAK siRNA effectively inhibited FAK and survivin expression in RELM-β-treated HPASMCs and partially suppressed cell proliferation. RELM-β promoted HPASMC proliferation and upregulated FAK and survivin expression. In conclusion, results suggested that FAK is upstream of survivin in the signaling pathway mediating cell proliferation. FAK seems to be important in RELM-β-induced HPASMC proliferation, partially by upregulating survivin expression. - Highlights: • rhRELM-β increased the expression of FAK and survivin. • rhRELM-β increased the proportion of HPASMCs in the S phase. • FAK is upstream of survivin in the signaling pathway mediating cell proliferation. • FAK is important in RELM-β-induced HPASMC proliferation, partly via survivin.

  2. Mechanical Coupling of Smooth Muscle Cells Using Microengineered Substrates and Local Stimulation

    Science.gov (United States)

    Copeland, Craig; Hunter, David; Tung, Leslie; Chen, Christopher; Reich, Daniel

    2013-03-01

    Mechanical stresses directly affect many cellular processes, including signal transduction, growth, differentiation, and survival. Cells can themselves generate such stresses by activating myosin to contract the actin cytoskeleton, which in turn can regulate both cell-substrate and cell-cell interactions. We are studying mechanical forces at cell-cell and cell-substrate interactions using arrays of selectively patterned flexible PDMS microposts combined with the ability to apply local chemical stimulation. Micropipette ``spritzing'', a laminar flow technique, uses glass micropipettes mounted on a microscope stage to deliver drugs to controlled regions within a cellular construct while cell traction forces are recorded via the micropost array. The pipettes are controlled by micromanipulators allowing for rapid and precise movement across the array and the ability to treat multiple constructs within a sample. This technique allows for observing the propagation of a chemically induced mechanical stimulus through cell-cell and cell-substrate interactions. We have used this system to administer the acto-myosin inhibitors Blebbistatin and Y-27632 to single cells and observed the subsequent decrease in cell traction forces. Experiments using trypsin-EDTA have shown this system to be capable of single cell manipulation through removal of one cell within a pair configuration while leaving the other cell unaffected. This project is supported in part by NIH grant HL090747

  3. Muscle injections with lidocaine improve resting fatigue and pain in patients with chronic fatigue syndrome

    Directory of Open Access Journals (Sweden)

    Staud R

    2017-06-01

    Full Text Available Roland Staud,1 Taylor Kizer,1 Michael E Robinson2 1Department of Medicine, College of Medicine, 2Department of Clinical and Health Psychology, University of Florida, Gainesville, FL, USA Objective: Patients with chronic fatigue syndrome (CFS complain of long-lasting fatigue and pain which are not relieved by rest and worsened by physical exertion. Previous research has implicated metaboreceptors of muscles to play an important role for chronic fatigue and pain. Therefore, we hypothesized that blocking impulse input from deep tissues with intramuscular lidocaine injections would improve not only the pain but also fatigue of CFS patients. Methods: In a double-blind, placebo-controlled study, 58 CFS patients received 20 mL of 1% lidocaine (200 mg or normal saline once into both trapezius and gluteal muscles. Study outcomes included clinical fatigue and pain, depression, and anxiety. In addition, mechanical and heat hyperalgesia were assessed and serum levels of lidocaine were obtained after the injections. Results: Fatigue ratings of CFS patients decreased significantly more after lidocaine compared to saline injections (p = 0.03. In contrast, muscle injections reduced pain, depression, and anxiety (p < 0.001, but these changes were not statistically different between lidocaine and saline (p > 0.05. Lidocaine injections increased mechanical pain thresholds of CFS patients (p = 0.04 but did not affect their heat hyperalgesia. Importantly, mood changes or lidocaine serum levels did not significantly predict fatigue reductions. Conclusion: These results demonstrate that lidocaine injections reduce clinical fatigue of CFS patients significantly more than placebo, suggesting an important role of peripheral tissues for chronic fatigue. Future investigations will be necessary to evaluate the clinical benefits of such interventions. Keywords: muscle injections, lidocaine, metaboreceptor, chronic fatigue 

  4. Contraction-stimulated glucose transport in muscle is controlled by AMPK and mechanical stress but not sarcoplasmatic reticulum Ca2+ release

    DEFF Research Database (Denmark)

    Jensen, Thomas Elbenhardt; Sylow, Lykke; Rose, Adam John

    2014-01-01

    signals through proteins such as AMPK. Here, we demonstrate in incubated mouse muscle that Ca(2+) release is neither sufficient nor strictly necessary to increase glucose transport. Rather, the glucose transport response is associated with metabolic feedback signals through AMPK, and mechanical stress......-activated signals. Furthermore, artificial stimulation of AMPK combined with passive stretch of muscle is additive and sufficient to elicit the full contraction glucose transport response. These results suggest that ATP-turnover and mechanical stress feedback are sufficient to fully increase glucose transport...

  5. Triiodothyronine Acutely Stimulates Glucose Transport into L6 Muscle Cells Without Increasing Surface GLUT4, GLUT1, or GLUT3

    Science.gov (United States)

    Teixeira, Silvania Silva; Tamrakar, Akhilesh K.; Goulart-Silva, Francemilson; Serrano-Nascimento, Caroline; Klip, Amira

    2012-01-01

    Background Thyroid hormones (THs) act genomically to stimulate glucose transport by elevating glucose transporter (Slc2a) expression and glucose utilization by cells. However, nongenomic effects of THs are now emerging. Here, we assess how triiodothyronine (T3) acutely affects glucose transport and the content of GLUT4, GLUT1, and GLUT3 at the surface of muscle cells, and possible interactions between T3 and insulin action. Methods Differentiated L6 myotubes transfected with myc-tagged Slc2a4 (L6-GLUT4myc) or Slc2a1 (L6-GLUT1myc) and wild-type L6 myotubes were studied in the following conditions: control, hypothyroid (Tx), Tx plus T3, Tx plus insulin, and Tx plus insulin and T3. Results Glucose uptake and GLUT4 content at the cell surface decreased in the Tx group relative to controls. T3 treatment for 30 minutes increased glucose transport into L6-GLUT4myc cells without altering surface GLUT4 content, which increased only thereafter. The total amount of GLUT4 protein remained unchanged among the groups studied. The surface GLUT1 content of L6-GLUT1myc cells also remained unaltered after T3 treatment; however, in these cells glucose transport was not stimulated by T3. In wild-type L6 cells, although T3 treatment increased the total amount of GLUT3, it did not change the surface GLUT3 content. Moreover, within 30 minutes, T3 stimulation of glucose uptake was additive to that of insulin in L6-GLUT4myc cells. As expected, insulin elevated surface GLUT4 content and glucose uptake. However, interestingly, surface GLUT4 content remained unchanged or even dropped with T3 plus insulin. Conclusions These data reveal that T3 rapidly increases glucose uptake in L6-GLUT4myc cells, which, at least for 30 minutes, did not depend on an increment in GLUT4 at the cell surface yet potentiates insulin action. We propose that this rapid T3 effect involves activation of GLUT4 transporters at the cell surface, but cannot discount the involvement of an unknown GLUT. PMID:22663547

  6. An exploratory study of voice change associated with healthy speakers after transcutaneous electrical stimulation to laryngeal muscles.

    Science.gov (United States)

    Fowler, Linda P; Gorham-Rowan, Mary; Hapner, Edie R

    2011-01-01

    The purpose of this study was to determine if measurable changes in fundamental frequency (F(0)) and relative sound level (RSL) occurred in healthy speakers after transcutaneous electrical stimulation (TES) as applied via VitalStim (Chattanooga Group, Chattanooga, TN). A prospective, repeated-measures design. Ten healthy female and 10 healthy male speakers, 20-53 years of age, participated in the study. All participants were nonsmokers and reported negative history for voice disorders. Participants received 1 hour of TES while engaged in eating, drinking, and conversation to simulate a typical dysphagia therapy protocol. Voice recordings were obtained before and immediately after TES. The voice samples consisted of a sustained vowel task and reading of the Rainbow Passage. Measurements of F(0) and RSL were obtained using TF32 (Milenkovic, 2005, University of Wisconsin). The participants also reported any sensations 5 minutes and 24 hours after TES. Measurable changes in F(0) and RSL were found for both tasks but were variable in direction and magnitude. These changes were not statistically significant. Subjective comments ranged from reports of a vocal warm-up feeling to delayed onset muscle soreness. These findings demonstrate that application of TES produces measurable changes in F(0) and RSL. However, the direction and magnitude of these changes are highly variable. Further research is needed to determine factors that may affect the extent to which TES contributes to significant changes in voice. Copyright © 2011 The Voice Foundation. Published by Mosby, Inc. All rights reserved.

  7. Mammalian target of rapamycin complex 1 activation is required for the stimulation of human skeletal muscle protein synthesis by essential amino acids.

    Science.gov (United States)

    Dickinson, Jared M; Fry, Christopher S; Drummond, Micah J; Gundermann, David M; Walker, Dillon K; Glynn, Erin L; Timmerman, Kyle L; Dhanani, Shaheen; Volpi, Elena; Rasmussen, Blake B

    2011-05-01

    The relationship between mammalian target of rapamycin complex 1 (mTORC1) signaling and muscle protein synthesis during instances of amino acid surplus in humans is based solely on correlational data. Therefore, the goal of this study was to use a mechanistic approach specifically designed to determine whether increased mTORC1 activation is requisite for the stimulation of muscle protein synthesis following L-essential amino acid (EAA) ingestion in humans. Examination of muscle protein synthesis and signaling were performed on vastus lateralis muscle biopsies obtained from 8 young (25 ± 2 y) individuals who were studied prior to and following ingestion of 10 g of EAA during 2 separate trials in a randomized, counterbalanced design. The trials were identical except during 1 trial, participants were administered a single oral dose of a potent mTORC1 inhibitor (rapamycin) prior to EAA ingestion. In response to EAA ingestion, an ~60% increase in muscle protein synthesis was observed during the control trial, concomitant with increased phosphorylation of mTOR (Ser(2448)), ribosomal S6 kinase 1 (Thr(389)), and eukaryotic initiation factor 4E binding protein 1 (Thr(37/46)). In contrast, prior administration of rapamycin completely blocked the increase in muscle protein synthesis and blocked or attenuated activation of mTORC1-signaling proteins. The inhibition of muscle protein synthesis and signaling was not due to differences in either extracellular or intracellular amino acid availability, because these variables were similar between trials. These data support a fundamental role for mTORC1 activation as a key regulator of human muscle protein synthesis in response to increased EAA availability. This information will be useful in the development of evidence-based nutritional therapies targeting mTORC1 to counteract muscle wasting associated with numerous clinical conditions.

  8. Citrulline stimulates muscle protein synthesis in the post-absorptive state in healthy people fed a low-protein diet – A pilot study

    Science.gov (United States)

    Jourdan, Marion; Nair, K. Sreekumaran; Carter, Rickey E.; Schimke, Jill; Ford, G. Charles; Marc, Julie; Aussel, Christian; Cynober, Luc

    2015-01-01

    Background and Aims Amino acid (AA) availability is critical to maintain protein homeostasis and reduced protein intake causes a decline in protein synthesis. Citrulline, an amino acid metabolite, has been reported to stimulate muscle protein synthesis in malnourished rats. Methods To determine whether citrulline stimulates muscle protein synthesis in healthy adults while on a low-protein diet, we studied 8 healthy participants twice in a cross-over study design. Following a 3-days of low-protein intake, either citrulline or a non-essential AA mixture (NEAA) was given orally as small boluses over the course of 8 hours. [ring-13C6] phenylalanine and [15N] tyrosine were administered as tracers to assess protein metabolism. Fractional synthesis rates (FSR) of muscle proteins were measured using phenylalanine enrichment in muscle tissue fluid as the precursor pool. Results FSR of mixed muscle protein was higher during the administration of citrulline than during NEAA (NEAA: 0.049 ± 0.005; citrulline: 0.060 ± 0.006; p=0.03), while muscle mitochondrial protein FSR and whole-body protein turnover were not different between the studies. Citrulline administration increased arginine and ornithine plasma concentrations without any effect on glucose, insulin, C-peptide, and IGF-1 levels. Citrulline administration did not promote mitochondria protein synthesis, transcripts, or citrate synthesis. Conclusions Citrulline ingestion enhances mixed muscle protein synthesis in healthy participants on 3-day low-protein intake. This anabolic action of citrulline appears to be independent of insulin action and may offer potential clinical application in conditions involving low amino acid intake. PMID:24972455

  9. Citrulline stimulates muscle protein synthesis in the post-absorptive state in healthy people fed a low-protein diet - A pilot study.

    Science.gov (United States)

    Jourdan, Marion; Nair, K Sreekumaran; Carter, Rickey E; Schimke, Jill; Ford, G Charles; Marc, Julie; Aussel, Christian; Cynober, Luc

    2015-06-01

    Amino acid (AA) availability is critical to maintain protein homeostasis and reduced protein intake causes a decline in protein synthesis. Citrulline, an amino acid metabolite, has been reported to stimulate muscle protein synthesis in malnourished rats. To determine whether citrulline stimulates muscle protein synthesis in healthy adults while on a low-protein diet, we studied 8 healthy participants twice in a cross-over study design. Following a 3-days of low-protein intake, either citrulline or a non-essential AA mixture (NEAA) was given orally as small boluses over the course of 8 h. [ring-(13)C6] phenylalanine and [(15)N] tyrosine were administered as tracers to assess protein metabolism. Fractional synthesis rates (FSR) of muscle proteins were measured using phenylalanine enrichment in muscle tissue fluid as the precursor pool. FSR of mixed muscle protein was higher during the administration of citrulline than during NEAA (NEAA: 0.049 ± 0.005; citrulline: 0.060 ± 0.006; P = 0.03), while muscle mitochondrial protein FSR and whole-body protein turnover were not different between the studies. Citrulline administration increased arginine and ornithine plasma concentrations without any effect on glucose, insulin, C-peptide, and IGF-1 levels. Citrulline administration did not promote mitochondria protein synthesis, transcripts, or citrate synthesis. Citrulline ingestion enhances mixed muscle protein synthesis in healthy participants on 3-day low-protein intake. This anabolic action of citrulline appears to be independent of insulin action and may offer potential clinical application in conditions involving low amino acid intake. Copyright © 2014. Published by Elsevier Ltd.

  10. Isolation and individual electrical stimulation of single smooth-muscle cells from the urinary bladder of the pig

    NARCIS (Netherlands)

    J.J. Glerum (Jacobus); R. van Mastrigt (Ron); J.C. Romijn (Johannes); D.J. Griffiths (Derek)

    1987-01-01

    textabstractIn contrast to striated muscle, measurements on strips of smooth muscle cannot be uniquely interpreted in terms of an array of contractile units. Therefore scaling down to the single-cell level is necessary to gain detailed understanding of the contractile process in this type of muscle.

  11. The effect of neuromuscular electrical stimulation on muscle strength, functional capacity and body composition in haemodialysis patients

    Directory of Open Access Journals (Sweden)

    Vicent Esteve

    2017-01-01

    Conclusions: (1 NMES improved muscle strength, functional capacity and quadriceps muscle composition in our patients. (2 Based on the results obtained, NMES could be a new therapeutic alternative to prevent muscle atrophy and progressive physical deterioration. (3 However, future studies are necessary to establish the potential beneficial effects of NMES in HD patients.

  12. Prolonged electrical stimulation-induced gluteal and hamstring muscle activation and sitting pressure in spinal cord injury: Effect of duty cycle

    OpenAIRE

    Christof A. J. Smit, MD; Karin J. A. Legemate, MSc; Anja de Koning, MSc; Sonja de Groot, PhD; Janneke M. Stolwijk-Swuste, MD, PhD; Thomas W. J. Janssen, PhD

    2013-01-01

    Pressure ulcers (PUs) are highly prevalent in people with spinal cord injury (SCI). Electrical stimulation (ES) activates muscles and might reduce risk factors. Our objectives were to study and compare the effects of two duty cycles during 3 h of ES-induced gluteal and hamstring activation on interface pressure distribution in sitting individuals with SCI and study the usability of a newly developed electrode garment (ES shorts). Ten individuals with SCI participated in this study, in which t...

  13. Impaired insulin-stimulated phosphorylation of Akt and AS160 in skeletal muscle of women with polycystic ovary syndrome is reversed by pioglitazone treatment

    DEFF Research Database (Denmark)

    Højlund, Kurt; Glintborg, Dorte; Andersen, Nicoline R

    2008-01-01

    , and we examined the effect of 16 weeks of treatment with pioglitazone in PCOS patients. RESULTS: Impaired insulin-mediated total (R(d)) oxidative and nonoxidative glucose disposal (NOGD) was paralleled by reduced insulin-stimulated Akt phosphorylation at Ser473 and Thr308 and AS160 phosphorylation......OBJECTIVE: Insulin resistance in skeletal muscle is a major risk factor for type 2 diabetes in women with polycystic ovary syndrome (PCOS). However, the molecular mechanisms underlying skeletal muscle insulin resistance and the insulin-sensitizing effect of thiazolidinediones in PCOS in vivo...... are less well characterized. RESEARCH DESIGN AND METHODS: We determined molecular mediators of insulin signaling to glucose transport in skeletal muscle biopsies of 24 PCOS patients and 14 matched control subjects metabolically characterized by euglycemic-hyperinsulinemic clamps and indirect calorimetry...

  14. Lean and Obese Zucker Rat Extensor Digitorum Longus Muscle high-frequency electrical stimulation (HFES Data: Regulation of p70S6kinase Associated Proteins

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    Kevin M. Rice

    2018-02-01

    Full Text Available Anaerobic exercise has been advocated as a prescribed treatment for the management of diabetes: however, alterations in exercise-induced signaling remain largely unexplored in the diabetic muscle. Here, we compare the basal and the in situ contraction-induced phosphorylation of the AKT, GSK3beta, mTor, p70s6K, Pten, and Shp2 in the lean and obese (fa/fa Zucker rat Extensor Digitorum Longus (EDL muscle following a single bout of contractile stimuli. This article represents data associated with prior publications from our lab (Katta et al., 2009a, 2009b; Tullgren et al., 1991 [1–3] and concurrent Data in Brief articles (Ginjupalli et al., 2017a, 2017b; Rice et al., 2017a, 2017b [4–7]. Keywords: Diabetes, Skeletal muscle, High-frequency electrical stimulation (HFES, Zucker rat, Extensor Digitorum Longus, p70s6k

  15. Role of cyclic AMP sensor Epac1 in masseter muscle hypertrophy and myosin heavy chain transition induced by β2-adrenoceptor stimulation.

    Science.gov (United States)

    Ohnuki, Yoshiki; Umeki, Daisuke; Mototani, Yasumasa; Jin, Huiling; Cai, Wenqian; Shiozawa, Kouichi; Suita, Kenji; Saeki, Yasutake; Fujita, Takayuki; Ishikawa, Yoshihiro; Okumura, Satoshi

    2014-12-15

    The predominant isoform of β-adrenoceptor (β-AR) in skeletal muscle is β2-AR and that in the cardiac muscle is β1-AR. We have reported that Epac1 (exchange protein directly activated by cAMP 1), a new protein kinase A-independent cAMP sensor, does not affect cardiac hypertrophy in response to pressure overload or chronic isoproterenol (isoprenaline) infusion. However, the role of Epac1 in skeletal muscle hypertrophy remains poorly understood. We thus examined the effect of disruption of Epac1, the major Epac isoform in skeletal muscle, on masseter muscle hypertrophy induced by chronic β2-AR stimulation with clenbuterol (CB) in Epac1-null mice (Epac1KO). The masseter muscle weight/tibial length ratio was similar in wild-type (WT) and Epac1KO at baseline and was significantly increased in WT after CB infusion, but this increase was suppressed in Epac1KO. CB treatment significantly increased the proportion of myosin heavy chain (MHC) IIb at the expense of that of MHC IId/x in both WT and Epac1KO, indicating that Epac1 did not mediate the CB-induced MHC isoform transition towards the faster isoform. The mechanism of suppression of CB-mediated hypertrophy in Epac1KO is considered to involve decreased activation of Akt signalling. In addition, CB-induced histone deacetylase 4 (HDAC4) phosphorylation on serine 246 mediated by calmodulin kinase II (CaMKII), which plays a role in skeletal muscle hypertrophy, was suppressed in Epac1KO. Our findings suggest that Epac1 plays a role in β2-AR-mediated masseter muscle hypertrophy, probably through activation of both Akt signalling and CaMKII/HDAC4 signalling. © 2014 The Authors. The Journal of Physiology © 2014 The Physiological Society.

  16. 40-Hz square-wave stimulation requires less energy to produce muscle contraction: compared with the TASER® X26 conducted energy weapon.

    Science.gov (United States)

    Comeaux, James A; Jauchem, James R; Cox, D Duane; Crane, Carrie C; D'Andrea, John A

    2013-07-01

    Conducted energy weapons (CEWs) (including the Advanced TASER(®) X26 model produced by TASER International, Inc.) incapacitate individuals by causing muscle contractions. In this study using anesthetized swine, the potential incapacitating effect of primarily monophasic, 19-Hz voltage imposed by the commercial CEW was compared with the effect of voltages imposed by a laboratory device that created 40-Hz square waves. Forces of muscle contraction were measured with the use of strain gauges. Stimulation with 40-Hz square waves required less pulse energy than stimulation with the commercial CEW to produce similar muscle contraction. The square-pulse stimulation, at the higher repetition rate, caused a more complete tetanus at a lower energy. Use of such a simple shape of waveform may be used to make future nonlethal weapon devices more efficient. © 2013 American Academy of Forensic Sciences Published 2013. This article is a U.S. Government work and is in the public domain in the U.S.A.

  17. 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.

  18. A novel PKB/Akt inhibitor, MK-2206, effectively inhibits insulin-stimulated glucose metabolism and protein synthesis in isolated rat skeletal muscle.

    Science.gov (United States)

    Lai, Yu-Chiang; Liu, Yang; Jacobs, Roxane; Rider, Mark H

    2012-10-01

    PKB (protein kinase B), also known as Akt, is a key component of insulin signalling. Defects in PKB activation lead to insulin resistance and metabolic disorders, whereas PKB overactivation has been linked to tumour growth. Small-molecule PKB inhibitors have thus been developed for cancer treatment, but also represent useful tools to probe the roles of PKB in insulin action. In the present study, we examined the acute effects of two allosteric PKB inhibitors, MK-2206 and Akti 1/2 (Akti) on PKB signalling in incubated rat soleus muscles. We also assessed the effects of the compounds on insulin-stimulated glucose uptake, glycogen and protein synthesis. MK-2206 dose-dependently inhibited insulin-stimulated PKB phosphorylation, PKBβ activity and phosphorylation of PKB downstream targets (including glycogen synthase kinase-3α/β, proline-rich Akt substrate of 40 kDa and Akt substrate of 160 kDa). Insulin-stimulated glucose uptake, glycogen synthesis and glycogen synthase activity were also decreased by MK-2206 in a dose-dependent manner. Incubation with high doses of MK-2206 (10 μM) inhibited insulin-induced p70 ribosomal protein S6 kinase and 4E-BP1 (eukaryotic initiation factor 4E-binding protein-1) phosphorylation associated with increased eEF2 (eukaryotic elongation factor 2) phosphorylation. In contrast, Akti only modestly inhibited insulin-induced PKB and mTOR (mammalian target of rapamycin) signalling, with little or no effect on glucose uptake and protein synthesis. MK-2206, rather than Akti, would thus be the tool of choice for studying the role of PKB in insulin action in skeletal muscle. The results point to a key role for PKB in mediating insulin-stimulated glucose uptake, glycogen synthesis and protein synthesis in skeletal muscle.

  19. Maximal Voluntary Activation of the Elbow Flexors Is under Predicted by Transcranial Magnetic Stimulation Compared to Motor Point Stimulation Prior to and Following Muscle Fatigue

    Directory of Open Access Journals (Sweden)

    Edward W. J. Cadigan

    2017-09-01

    Full Text Available Transcranial magnetic (TMS and motor point stimulation have been used to determine voluntary activation (VA. However, very few studies have directly compared the two stimulation techniques for assessing VA of the elbow flexors. The purpose of this study was to compare TMS and motor point stimulation for assessing VA in non-fatigued and fatigued elbow flexors. Participants performed a fatigue protocol that included twelve, 15 s isometric elbow flexor contractions. Participants completed a set of isometric elbow flexion contractions at 100, 75, 50, and 25% of maximum voluntary contraction (MVC prior to and following fatigue contractions 3, 6, 9, and 12 and 5 and 10 min post-fatigue. Force and EMG of the bicep and triceps brachii were measured for each contraction. Force responses to TMS and motor point stimulation and EMG responses to TMS (motor evoked potentials, MEPs and Erb's point stimulation (maximal M-waves, Mmax were also recorded. VA was estimated using the equation: VA% = (1−SITforce/PTforce × 100. The resting twitch was measured directly for motor point stimulation and estimated for both motor point stimulation and TMS by extrapolation of the linear regression between the superimposed twitch force and voluntary force. MVC force, potentiated twitch force and VA significantly (p < 0.05 decreased throughout the elbow flexor fatigue protocol and partially recovered 10 min post fatigue. VA was significantly (p < 0.05 underestimated when using TMS compared to motor point stimulation in non-fatigued and fatigued elbow flexors. Motor point stimulation compared to TMS superimposed twitch forces were significantly (p < 0.05 higher at 50% MVC but similar at 75 and 100% MVC. The linear relationship between TMS superimposed twitch force and voluntary force significantly (p < 0.05 decreased with fatigue. There was no change in triceps/biceps electromyography, biceps/triceps MEP amplitudes, or bicep MEP amplitudes throughout the fatigue protocol at

  20. Effect of stimulus parameters and contraction level on inhibitory responses in human jaw-closing muscles: Implications for contingent stimulation

    DEFF Research Database (Denmark)

    Jadidi, F; Wang, K; Arendt-Nielsen, Lars

    2009-01-01

      Objective: Examine the effect of stimulus duration as well as stimulus intensity and level of muscle contraction on the inhibitory responses in human jaw-closing muscles. Design: The inhibitory jaw-reflexes, ES1 and ES2, were recorded in the surface electromyogram (EMG) of masseter and temporal...

  1. 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...

  2. 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

  3. Efficient generation of smooth muscle cells from adipose-derived stromal cells by 3D mechanical stimulation can substitute the use of growth factors in vascular tissue engineering.

    Science.gov (United States)

    Parvizi, Mojtaba; Bolhuis-Versteeg, Lydia A M; Poot, André A; Harmsen, Martin C

    2016-07-01

    Occluding artery disease causes a high demand for bioartificial replacement vessels. We investigated the combined use of biodegradable and creep-free poly (1,3-trimethylene carbonate) (PTMC) with smooth muscle cells (SMC) derived by biochemical or mechanical stimulation of adipose tissue-derived stromal cells (ASC) to engineer bioartificial arteries. Biochemical induction of cultured ASC to SMC was done with TGF-β1 for 7d. Phenotype and function were assessed by qRT-PCR, immunodetection and collagen contraction assays. The influence of mechanical stimulation on non-differentiated and pre-differentiated ASC, loaded in porous tubular PTMC scaffolds, was assessed after culturing under pulsatile flow for 14d. Assays included qRT-PCR, production of extracellular matrix and scanning electron microscopy. ASC adhesion and TGF-β1-driven differentiation to contractile SMC on PTMC did not differ from tissue culture polystyrene controls. Mesenchymal and SMC markers were increased compared to controls. Interestingly, pre-differentiated ASC had only marginal higher contractility than controls. Moreover, in 3D PTMC scaffolds, mechanical stimulation yielded well-aligned ASC-derived SMC which deposited ECM. Under the same conditions, pre-differentiated ASC-derived SMC maintained their SMC phenotype. Our results show that mechanical stimulation can replace TGF-β1 pre-stimulation to generate SMC from ASC and that pre-differentiated ASC keep their SMC phenotype with increased expression of SMC markers. Copyright © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Effects of Force Load, Muscle Fatigue, and Magnetic Stimulation on Surface Electromyography during Side Arm Lateral Raise Task: A Preliminary Study with Healthy Subjects.

    Science.gov (United States)

    Cao, Liu; Wang, Ying; Hao, Dongmei; Rong, Yao; Yang, Lin; Zhang, Song; Zheng, Dingchang

    2017-01-01

    The aim of this study was to quantitatively investigate the effects of force load, muscle fatigue, and extremely low-frequency (ELF) magnetic stimulation on surface electromyography (SEMG) signal features during side arm lateral raise task. SEMG signals were recorded from 18 healthy subjects on the anterior deltoid using a BIOSEMI ActiveTwo system during side lateral raise task (with the right arm 90 degrees away from the body) with three different loads on the forearm (0 kg, 1 kg, and 3 kg; their order was randomized between subjects). The arm maintained the loads until the subject felt exhausted. The first 10 s recording for each load was regarded as nonfatigue status and the last 10 s before the subject was exhausted was regarded as fatigue status. The subject was then given a five-minute resting between different loads. Two days later, the same experiment was repeated on every subject, and this time the ELF magnetic stimulation was applied to the subject's deltoid muscle during the five-minute rest period. Three commonly used SEMG features, root mean square (RMS), median frequency (MDF), and sample entropy (SampEn), were analyzed and compared between different loads, nonfatigue/fatigue status, and ELF stimulation and no stimulation. Variance analysis results showed that the effect of force load on RMS was significant ( p 0.05). In comparison with nonfatigue status, for all the different force loads with and without ELF stimulation, RMS was significantly larger at fatigue (all p < 0.001) and MDF and SampEn were significantly smaller (all p < 0.001).

  5. Effects of Force Load, Muscle Fatigue, and Magnetic Stimulation on Surface Electromyography during Side Arm Lateral Raise Task: A Preliminary Study with Healthy Subjects

    Directory of Open Access Journals (Sweden)

    Liu Cao

    2017-01-01

    Full Text Available The aim of this study was to quantitatively investigate the effects of force load, muscle fatigue, and extremely low-frequency (ELF magnetic stimulation on surface electromyography (SEMG signal features during side arm lateral raise task. SEMG signals were recorded from 18 healthy subjects on the anterior deltoid using a BIOSEMI ActiveTwo system during side lateral raise task (with the right arm 90 degrees away from the body with three different loads on the forearm (0 kg, 1 kg, and 3 kg; their order was randomized between subjects. The arm maintained the loads until the subject felt exhausted. The first 10 s recording for each load was regarded as nonfatigue status and the last 10 s before the subject was exhausted was regarded as fatigue status. The subject was then given a five-minute resting between different loads. Two days later, the same experiment was repeated on every subject, and this time the ELF magnetic stimulation was applied to the subject’s deltoid muscle during the five-minute rest period. Three commonly used SEMG features, root mean square (RMS, median frequency (MDF, and sample entropy (SampEn, were analyzed and compared between different loads, nonfatigue/fatigue status, and ELF stimulation and no stimulation. Variance analysis results showed that the effect of force load on RMS was significant (p0.05. In comparison with nonfatigue status, for all the different force loads with and without ELF stimulation, RMS was significantly larger at fatigue (all p<0.001 and MDF and SampEn were significantly smaller (all p<0.001.

  6. Muscle Recruitment and Coordination following Constraint-Induced Movement Therapy with Electrical Stimulation on Children with Hemiplegic Cerebral Palsy: A Randomized Controlled Trial.

    Directory of Open Access Journals (Sweden)

    Kaishou Xu

    Full Text Available To investigate changes of muscle recruitment and coordination following constraint-induced movement therapy, constraint-induced movement therapy plus electrical stimulation, and traditional occupational therapy in treating hand dysfunction.In a randomized, single-blind, controlled trial, children with hemiplegic cerebral palsy were randomly assigned to receive constraint-induced movement therapy (n = 22, constraint-induced movement therapy plus electrical stimulation (n = 23, or traditional occupational therapy (n = 23. Three groups received a 2-week hospital-based intervention and a 6-month home-based exercise program following hospital-based intervention. Constraint-induced movement therapy involved intensive functional training of the involved hand during which the uninvolved hand was constrained. Electrical stimulation was applied on wrist extensors of the involved hand. Traditional occupational therapy involved functional unimanual and bimanual training. All children underwent clinical assessments and surface electromyography (EMG at baseline, 2 weeks, 3 and 6 months after treatment. Surface myoelectric signals were integrated EMG, root mean square and cocontraction ratio. Clinical measures were grip strength and upper extremity functional test.Constraint-induced movement therapy plus electrical stimulation group showed both a greater rate of improvement in integrated EMG of the involved wrist extensors and cocontraction ratio compared to the other two groups at 3 and 6 months, as well as improving in root mean square of the involved wrist extensors than traditional occupational therapy group (p<0.05. Positive correlations were found between both upper extremity functional test scores and integrated EMG of the involved wrist as well as grip strength and integrated EMG of the involved wrist extensors (p<0.05.Constraint-induced movement therapy plus electrical stimulation is likely to produce the best outcome in improving muscle recruitment

  7. Electrical stimulation of paralyzed vibrissal muscles reduces endplate reinnervation and does not promote motor recovery after facial nerve repair in rats.

    Science.gov (United States)

    Sinis, Nektarios; Horn, Frauke; Genchev, Borislav; Skouras, Emmanouil; Merkel, Daniel; Angelova, Srebrina K; Kaidoglou, Katerina; Michael, Joern; Pavlov, Stoyan; Igelmund, Peter; Schaller, Hans-Eberhard; Irintchev, Andrey; Dunlop, Sarah A; Angelov, Doychin N

    2009-10-01

    The outcome of peripheral nerve injuries requiring surgical repair is poor. Recent work has suggested that electrical stimulation (ES) of denervated muscles could be beneficial. Here we tested whether ES has a positive influence on functional recovery after injury and surgical repair of the facial nerve. Outcomes at 2 months were compared to animals receiving sham stimulation (SS). Starting on the first day after end-to-end suture (facial-facial anastomosis), electrical stimulation (square 0.1 ms pulses at 5 Hz at an ex tempore established threshold amplitude of between 3.0 and 5.0V) was delivered to the vibrissal muscles for 5 min a day, 3 times a week. Restoration of vibrissal motor performance following ES or SS was evaluated using the video-based motion analysis and correlated with the degree of collateral axonal branching at the lesion site, the number of motor endplates in the target musculature and the quality of their reinnervation, i.e. the degree of mono- versus poly-innervation. Neither protocol reduced collateral branching. ES did not improve functional outcome, but rather reduced the number of innervated motor endplates to approximately one-fifth of normal values and failed to reduce the proportion of poly-innervated motor endplates. We conclude that ES is not beneficial for recovery of whisker function after facial nerve repair in rats.

  8. The effects of elevated levels of sodium bicarbonate (NaHCO₃) on the acute power output and time to fatigue of maximally stimulated mouse soleus and EDL muscles.

    Science.gov (United States)

    Higgins, M F; Tallis, J; Price, M J; James, R S

    2013-05-01

    This study examined the effects of elevated buffer capacity [~32 mM HCO₃(-)] through administration of sodium bicarbonate (NaHCO₃) on maximally stimulated isolated mouse soleus (SOL) and extensor digitorum longus (EDL) muscles undergoing cyclical length changes at 37 °C. The elevated buffering capacity was of an equivalent level to that achieved in humans with acute oral supplementation. We evaluated the acute effects of elevated [HCO₃(-)] on (1) maximal acute power output (PO) and (2) time to fatigue to 60 % of maximum control PO (TLIM60), the level of decline in muscle PO observed in humans undertaking similar exercise, using the work loop technique. Acute PO was on average 7.0 ± 4.8 % greater for NaHCO₃-treated EDL muscles (P < 0.001; ES = 2.0) and 3.6 ± 1.8 % greater for NaHCO₃-treated SOL muscles (P < 0.001; ES = 2.3) compared to CON. Increases in PO were likely due to greater force production throughout shortening. The acute effects of NaHCO₃ on EDL were significantly greater (P < 0.001; ES = 0.9) than on SOL. Treatment of EDL (P = 0.22; ES = 0.6) and SOL (P = 0.19; ES = 0.9) with NaHCO₃ did not alter the pattern of fatigue. Although significant differences were not observed in whole group data, the fatigability of muscle performance was variable, suggesting that there might be inter-individual differences in response to NaHCO₃ supplementation. These results present the best indication to date that NaHCO₃ has direct peripheral effects on mammalian skeletal muscle resulting in increased acute power output.

  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. Corticomotor control of lumbar multifidus muscles is impaired in chronic low back pain: concurrent evidence from ultrasound imaging and double-pulse transcranial magnetic stimulation.

    Science.gov (United States)

    Massé-Alarie, Hugo; Beaulieu, Louis-David; Preuss, Richard; Schneider, Cyril

    2016-04-01

    Chronic low back pain (CLBP) is often associated with impaired control of deep trunk muscles and reorganization of the primary motor areas (M1). Precisely, functional changes of the lumbar multifidus muscles (MF) involved in spine stability may be of special interest in rehabilitation. Therefore, we tested MF corticomotor control using double transcranial magnetic stimulation (TMS) paradigms for the first time in this muscle and examined its link with MF volitional activation. Eleven individuals with lateralized CLBP and 13 pain-free participants were recruited. Ultrasound imaging enabled measurement of MF volitional isometric contraction in prone lying. TMS of MF M1 area was used to test hemispheric excitability and mechanisms in relation to motor programming, i.e., active motor threshold (AMT), amplitude of motor-evoked potentials and short-interval intracortical inhibition (SICI) and facilitation (SICF). In CLBP, SICI level was lower in the left hemisphere and MF volitional contraction was not related to AMT (M1 excitability), conversely to what was observed in the pain-free group. No other between-group difference was detected. These original findings support a plasticity of cortical maps controlling paravertebral muscles and likely including a different motor strategy for the control of MF. Changes of M1 function may thus underlie impaired motor control of lumbopelvic spine and pain persistence in CLBP.

  11. Nutrient-induced stimulation of protein synthesis in mouse skeletal muscle is limited by the mTORC1 repressor REDD1.

    Science.gov (United States)

    Gordon, Bradley S; Williamson, David L; Lang, Charles H; Jefferson, Leonard S; Kimball, Scot R

    2015-04-01

    In skeletal muscle, the nutrient-induced stimulation of protein synthesis requires signaling through the mechanistic target of rapamycin complex 1 (mTORC1). Expression of the repressor of mTORC1 signaling, regulated in development and DNA damage 1 (REDD1), is elevated in muscle during various atrophic conditions and diminished under hypertrophic conditions. The question arises as to what extent REDD1 limits the nutrient-induced stimulation of protein synthesis. The objective was to examine the role of REDD1 in limiting the response of muscle protein synthesis and mTORC1 signaling to a nutrient stimulus. Wild type REDD1 gene (REDD1(+/+)) and disruption in the REDD1 gene (REDD1(-/-)) mice were feed deprived for 16 h and randomized to remain feed deprived or refed for 15 or 60 min. The tibialis anterior was then removed for analysis of protein synthesis and mTORC1 signaling. In feed-deprived mice, protein synthesis and mTORC1 signaling were significantly lower in REDD1(+/+) than in REDD1(-/-) mice. Thirty minutes after the start of refeeding, protein synthesis in REDD1(+/+) mice was stimulated by 28%, reaching a value similar to that observed in feed-deprived REDD1(-/-) mice, and was accompanied by increased phosphorylation of mTOR (Ser2448), p70S6K1 (Thr389), and 4E-BP1 (Ser65) by 81%, 167%, and 207%, respectively. In refed REDD1(-/-) mice, phosphorylation of mTOR (Ser2448), p70S6K1 (Thr389), and 4E-BP1 (Ser65) were significantly augmented above the values observed in refed REDD1(+/+) mice by 258%, 405%, and 401%, respectively, although protein synthesis was not coordinately increased. Seventy-five minutes after refeeding, REDD1 expression in REDD1(+/+) mice was reduced (∼15% of feed-deprived REDD1(+/+) values), and protein synthesis and mTORC1 signaling were not different between refed REDD1(+/+) mice and REDD1(-/-) mice. The results show that REDD1 expression limits protein synthesis in mouse skeletal muscle by inhibiting mTORC1 signaling during periods of feed

  12. IGF-I Stimulates Cooperative Interaction between the IGF-I Receptor and CSK Homologous Kinase that Regulates SHPS-1 Phosphorylation in Vascular Smooth Muscle Cells

    Science.gov (United States)

    Radhakrishnan, Yashwanth; Shen, Xinchun; Maile, Laura A.; Xi, Gang

    2011-01-01

    IGF-I plays an important role in smooth muscle cell proliferation and migration. In vascular smooth muscle cells cultured in 25 mm glucose, IGF-I stimulated a significant increase in Src homology 2 domain containing protein tyrosine phosphatase substrate-1 (SHPS-1) phosphorylation compared with 5 mm glucose and this increase was required for smooth muscle cell proliferation. A proteome-wide screen revealed that carboxyl-terminal SRC kinase homologous kinase (CTK) bound directly to phosphotyrosines in the SHPS-1 cytoplasmic domain. Because the kinase(s) that phosphorylates these tyrosines in response to IGF-I is unknown, we determined the roles of IGF-I receptor (IGF-IR) and CTK in mediating SHPS-1 phosphorylation. After IGF-I stimulation, CTK was recruited to IGF-IR and subsequently to phospho-SHPS-1. Expression of an IGF-IR mutant that eliminated CTK binding reduced CTK transfer to SHPS-1, SHPS-1 phosphorylation, and cell proliferation. IGF-IR phosphorylated SHPS-1, which provided a binding site for CTK. CTK recruitment to SHPS-1 resulted in a further enhancement of SHPS-1 phosphorylation. CTK knockdown also impaired IGF-I-stimulated SHPS-1 phosphorylation and downstream signaling. Analysis of specific tyrosines showed that mutation of tyrosines 428/452 in SHPS-1 to phenylalanine reduced SHPS-1 phosphorylation but allowed CTK binding. In contrast, the mutation of tyrosines 469/495 inhibited IGF-IR-mediated the phosphorylation of SHPS-1 and CTK binding, suggesting that IGF-IR phosphorylated Y469/495, allowing CTK binding, and that CTK subsequently phosphorylated Y428/452. Based on the above findings, we conclude that after IGF-I stimulation, CTK is recruited to IGF-IR and its recruitment facilitates CTK's subsequent association with phospho-SHPS-1. This results in the enhanced CTK transfer to SHPS-1, and the two kinases then fully phosphorylate SHPS-1, which is necessary for IGF-I stimulated cellular proliferation. PMID:21799000

  13. Application of neuromuscular electrical stimulation of the lower limb skeletal muscles in the rehabilitation of patients with chronic heart failure and chronic obstructive pulmonary disease

    Directory of Open Access Journals (Sweden)

    Ewa Barbara Kucio

    2017-03-01

    Full Text Available Increasing physical activity is a widely-known method of rehabilitation of patients with chronic heart failure (CHF and chronic obstructive pulmonary disease (COPD. However, what kind of procedure is to be applied if a patient suffers from advanced heart or respiratory failure, cannot undertake physical exercise due to locomotor system disorders or is currently undergoing respiratorotherapy? Recent research shows that neuromuscular electrical stimulation of the lower limb skeletal muscles (NMES may comprise an alternative to physical training in patients with CHF and COPD. The aim of this study is to summarize the current state of knowledge on the use of NMES in cardiac rehabilitation of patients with CHF and pulmonary rehabilitation of patients with COPD. As demonstrated in recent research on the topic, NMES – due to forcing the muscles to activate – increases exercise tolerance, muscle mass and endurance in patients with CHF and COPD. The beneficial effect of NMES on blood circulation in the muscles, aerobic enzymes activity, functioning of the vascular endothelium, reduction of pro-inflammatory cytokines concentration and increased quality of life has also been presented. It is to be accentuated that NMES treatment, due to lesser physical exertion and, in turn, a decreased feeling of dyspnea are more comfortable for the patient than traditional physical training. Moreover, NMES treatment, after foregoing training, can be applied at home. Potential side effects include transient muscle pain and minor skin damage due to improper positioning of the electrodes. To summarize, NMES treatment is well received by CHF and COPD patients and brings about increased exercise tolerance, as well as better quality of life. Devices used for NMES therapy, due to progressive miniaturization, are easily accessible and relatively inexpensive.

  14. NF-κB activity in muscle from obese and type 2 diabetic subjects under basal and exercise-stimulated conditions.

    Science.gov (United States)

    Tantiwong, Puntip; Shanmugasundaram, Karthigayan; Monroy, Adriana; Ghosh, Sangeeta; Li, Mengyao; DeFronzo, Ralph A; Cersosimo, Eugenio; Sriwijitkamol, Apiradee; Mohan, Sumathy; Musi, Nicolas

    2010-11-01

    NF-κB is a transcription factor that controls the gene expression of several proinflammatory proteins. Cell culture and animal studies have implicated increased NF-κB activity in the pathogenesis of insulin resistance and muscle atrophy. However, it is unclear whether insulin-resistant human subjects have abnormal NF-κB activity in muscle. The effect that exercise has on NF-κB activity/signaling also is not clear. We measured NF-κB DNA-binding activity and the mRNA level of putative NF-κB-regulated myokines interleukin (IL)-6 and monocyte chemotactic protein-1 (MCP-1) in muscle samples from T2DM, obese, and lean subjects immediately before, during (40 min), and after (210 min) a bout of moderate-intensity cycle exercise. At baseline, NF-κB activity was elevated 2.1- and 2.7-fold in obese nondiabetic and T2DM subjects, respectively. NF-κB activity was increased significantly at 210 min following exercise in lean (1.9-fold) and obese (2.6-fold) subjects, but NF-κB activity did not change in T2DM. Exercise increased MCP-1 mRNA levels significantly in the three groups, whereas IL-6 gene expression increased significantly only in lean and obese subjects. MCP-1 and IL-6 gene expression peaked at the 40-min exercise time point. We conclude that insulin-resistant subjects have increased basal NF-κB activity in muscle. Acute exercise stimulates NF-κB in muscle from nondiabetic subjects. In T2DM subjects, exercise had no effect on NF-κB activity, which could be explained by the already elevated NF-κB activity at baseline. Exercise-induced MCP-1 and IL-6 gene expression precedes increases in NF-κB activity, suggesting that other factors promote gene expression of these cytokines during exercise.

  15. Spatial distribution of motor units recruited during electrical stimulation of the quadriceps muscle versus the femoral nerve.

    Science.gov (United States)

    Rodriguez-Falces, Javier; Maffiuletti, Nicola A; Place, Nicolas

    2013-11-01

    In this study we investigated differences in the spatial recruitment of motor units (MUs) in the quadriceps when electrical stimulation is applied over the quadriceps belly versus the femoral nerve. M-waves and mechanical twitches were evoked using over-the-quadriceps and femoral nerve stimulation of gradually increasing intensity from 22 young, healthy subjects. Spatial recruitment was investigated using recruitment curves of M-waves recorded from the vastus medialis (VM) and vastus lateralis (VL) and of twitches recorded from the quadriceps. At maximal stimulation intensity (Imax), no differences were found between nerve and over-the-quadriceps stimulation. At submaximal intensities, VL M-wave amplitude was higher for over-the-quadriceps stimulation at 40% Imax, and peak twitch force was greater for nerve stimulation at 60% and 80% Imax. For the VM, MU spatial recruitment during nerve and over-the-quadriceps stimulation of increasing intensity occurred in a similar manner, whereas significant differences were observed for the VL. Copyright © 2013 Wiley Periodicals, Inc.

  16. Electrically Stimulated Antagonist Muscle Contraction Increased Muscle Mass and Bone Mineral Density of One Astronaut - Initial Verification on the International Space Station

    OpenAIRE

    Shiba, Naoto; Matsuse, Hiroo; Takano, Yoshio; Yoshimitsu, Kazuhiro; Omoto, Masayuki; Hashida, Ryuki; Tagawa, Yoshihiko; Inada, Tomohisa; Yamada, Shin; Ohshima, Hiroshi

    2015-01-01

    Background Musculoskeletal atrophy is one of the major problems of extended periods of exposure to weightlessness such as on the International Space Station (ISS). We developed the Hybrid Training System (HTS) to maintain an astronaut?s musculoskeletal system using an electrically stimulated antagonist to resist the volitional contraction of the agonist instead of gravity. The present study assessed the system?s orbital operation capability and utility, as well as its preventative effect on a...

  17. Failure of activation of spinal motoneurones after muscle fatigue in healthy subjects studied by transcranial magnetic stimulation

    DEFF Research Database (Denmark)

    Andersen, Birgit; Westlund, Barbro; Krarup, Christian

    2003-01-01

    . This points to increased probability of repetitive spinal MN activation during fatigue even if some MNs in the pool failed to discharge. Silent period duration following cortical stimulation lengthened by an average of 55 ms after the contraction and recovered within a time course similar to that of the TST......During a sustained maximal effort a progressive decline in the ability to drive motoneurones (MNs) develops. We used the recently developed triple stimulation technique (TST) to study corticospinal conduction after fatiguing exercise in healthy subjects. This method employs a collision technique...... conventional transcranial magnetic stimulation (TMS) and responses to peripheral nerve stimulation were recorded following the same fatigue protocol. The size of both the MEPs and the peripheral responses increased after the contraction and were in direct contrast to the decrease in size of the TST response...

  18. Increased probability of repetitive spinal motoneuron activation by transcranial magnetic stimulation after muscle fatigue in healthy subjects

    DEFF Research Database (Denmark)

    Andersen, Birgit; Felding, Ulrik Ascanius; Krarup, Christian

    2012-01-01

    Triple stimulation technique (TST) has previously shown that transcranial magnetic stimulation (TMS) fails to activate a proportion of spinal motoneurons (MNs) during motor fatigue. The TST response depression without attenuation of the conventional motor evoked potential suggested increased...... probability of repetitive spinal MN activation during exercise even if some MNs failed to discharge by the brain stimulus. Here we used a modified TST (Quadruple stimulation; QuadS and Quintuple stimulation; QuintS) to examine the influence of fatiguing exercise on second and third MN discharges after......, reflecting that a greater proportion of spinal MNs were activated 2 or 3 times by the transcranial stimulus. The size of QuadS responses did not return to pre-contraction levels during 10 min observation time indicating long-lasting increase in excitatory input to spinal MNs. In addition, the post...

  19. Expression profiling of skeletal muscle following acute and chronic β2-adrenergic stimulation: implications for hypertrophy, metabolism and circadian rhythm

    Directory of Open Access Journals (Sweden)

    Lynch Gordon S

    2009-09-01

    Full Text Available Abstract Background Systemic administration of β-adrenoceptor (β-AR agonists has been found to induce skeletal muscle hypertrophy and significant metabolic changes. In the context of energy homeostasis, the importance of β-AR signaling has been highlighted by the inability of β1-3-AR-deficient mice to regulate energy expenditure and susceptibility to diet induced obesity. However, the molecular pathways and gene expression changes that initiate and maintain these phenotypic modulations are poorly understood. Therefore, the aim of this study was to identify differential changes in gene expression in murine skeletal muscle associated with systemic (acute and chronic administration of the β2-AR agonist formoterol. Results Skeletal muscle gene expression (from murine tibialis anterior was profiled at both 1 and 4 hours following systemic administration of the β2-AR agonist formoterol, using Illumina 46K mouse BeadArrays. Illumina expression profiling revealed significant expression changes in genes associated with skeletal muscle hypertrophy, myoblast differentiation, metabolism, circadian rhythm, transcription, histones, and oxidative stress. Differentially expressed genes relevant to the regulation of muscle mass and metabolism (in the context of the hypertrophic phenotype were further validated by quantitative RT-PCR to examine gene expression in response to both acute (1-24 h and chronic administration (1-28 days of formoterol at multiple timepoints. In terms of skeletal muscle hypertrophy, attenuation of myostatin signaling (including differential expression of myostatin, activin receptor IIB, phospho-Smad3 etc was observed following acute and chronic administration of formoterol. Acute (but not chronic administration of formoterol also significantly induced the expression of genes involved in oxidative metabolism, including hexokinase 2, sorbin and SH3 domain containing 1, and uncoupling protein 3. Interestingly, formoterol

  20. [Positions of the implanted stimulating electrodes for artificial facial nerve for inducing contraction of the orbicularis oris muscle in rabbit with peripheral facial paralysis].

    Science.gov (United States)

    Xu, D Y; Zhao, N J; Zhao, Y X; Luo, D; Sun, Y J; Li, K Y

    2017-11-07

    Objective: To explore the optimal positions of the implanted stimulating eletrodes for artificial facial nerve (AFN) for inducing contraction of the orbicularis oris muscle (OOM) in rabbit with peripheral facial paralysis. Methods: According to the four microelectrodes of the AFN stimulating side, four modes of the implanted positions were divided. In line with different modes, the electrodes were implanted into the affected OOM of the rabbits with unilateral peripheral facial paralysis. AFN output electric stimulation to induce contraction of the affected OOM with uniform stimulating frequency and pulse length in vitro. Then compared the stimulus threshold amplitude and the peak amplitude separately among different modes by SAS 9.3 version statistical software. Results: The differences of the stimulus threshold amplitude and the peak amplitude had no statistically significant separately between the first mode and the second mode ( P >0.05), but there were statistically significant differences between the third mode and the fourth mode ( P <0.05). Both kinds of the amplitudes were approximated between the first mode and the second mode respectively, and higher than those in the third mode or the fourth mode. Furthermore, both kinds of the amplitudes in the fourth mode were higher than those in the third mode. Conclusions: The microelectrodes of the AFN stimulating lateral are implanted into the upper lip with a public microelectrode and an output microelectrode, into the lower lip with an output microelectrode, and into the way, which is located to the angle 40° to 45° about the line joining between the midpoint of the ipsilateral auricle root and the corner of the mouth with an output microelectrode. This is the third positional mode which requires lowest effective stimulus current intensity. Thus the mode is suitable as the optimal placement programme.

  1. Electrical stimulation-induced Gluteal and Hamstring muscle activation can reduce sitting pressure in individuals with a spinal cord injury

    NARCIS (Netherlands)

    Janssen, T. W J; De Koning, A.; Legemate, K. J A; Smit, C. A J

    2010-01-01

    Individuals with spinal cord injury (SCI) are at high risk of developing pressure sores, in part due to high sitting pressures under the buttocks. PURPOSE: To evaluate the effect of ES-induced activation of the gluteal and hamstring muscles on the sitting pressure in individuals with SCI. METHODS:

  2. Rac1 governs exercise-stimulated glucose uptake in skeletal muscle through regulation of GLUT4 translocation in mice

    DEFF Research Database (Denmark)

    Sylow, Lykke; Laurent, Ida; Kleinert, Maximilian

    2016-01-01

    is a candidate molecule. This study investigated the role of Rac1 in muscle glucose uptake and substrate utilization during treadmill exercise in mice in vivo. Exercise-induced uptake of radiolabelled 2-deoxyglucose (2-DG) at 65% max running capacity was blocked in soleus and decreased by 80 and 60...

  3. Endotoxemia stimulates skeletal muscle Na+-K+-ATPase and raises blood lactate under aerobic conditions in humans

    DEFF Research Database (Denmark)

    Bundgaard, Henning; Kjeldsen, Keld; Suarez Krabbe, Karen

    2002-01-01

    We assessed the hypothesis that the epinephrine surge present during sepsis accelerates aerobic glycolysis and lactate production by increasing activity of skeletal muscle Na(+)-K(+)-ATPase. Healthy volunteers received an intravenous bolus of endotoxin or placebo in a randomized order on two...

  4. Transcutaneous electrical nerve stimulator of 5000 Hz frequency provides better analgesia than that of 100 Hz frequency in mice muscle pain model

    Directory of Open Access Journals (Sweden)

    Hung-Tsung Hsiao

    2017-04-01

    Full Text Available Transcutaneous electrical nerve stimulators (TENSs have been proved to be effective in muscle pain management for several decades. However, there is no consensus for the optimal TENS program. Previous research demonstrated that a 100 Hz TENS (L-TENS provided better analgesia than a conventional TENS ( 100 Hz TENS with a 100 Hz TENS. We used a 5000 Hz (5 kHz frequency TENS (M-TENS and an L-TENS to compare analgesic effect on a mice skin/muscle incision retraction model. Three groups of mice were used (sham, L-TENS, and M-TENS and applied with different TENS programs on Day 4 after the mice skin/muscle incision retraction model; TENS therapy was continued as 20 min/d for 3 days. Mice analgesic effects were measured via Von Frey microfilaments with the up–down method. After therapy, mice spinal cord dorsal horn and dorsal root ganglion (DRG were harvested for cytokine evaluation (tumor necrosis factor-α and interleukin-1β with the Western blotting method. Our data demonstrated that the M-TENS produced better analgesia than the L-TENS. Cytokine in the spinal cord or DRG all expressed lower than that of the sham group. However, there is no difference in both cytokine levels between TENSs of different frequencies in the spinal cord and DRG. We concluded that the M-TENS produced faster and better mechanical analgesia than the L-TENS in the mice skin/muscle incision retraction model. Those behavior differences were not in accordance with cytokine changes in the spinal cord or DRG.

  5. Effects of Neuromuscular Electrical Stimulation on the Masticatory Muscles and Physiologic Sleep Variables in Adults with Cerebral Palsy: A Novel Therapeutic Approach.

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    Lilian Chrystiane Giannasi

    Full Text Available Cerebral palsy (CP is a term employed to define a group of non-progressive neuromotor disorders caused by damage to the immature or developing brain, with consequent limitations regarding movement and posture. CP may impair orapharygeal muscle tone, leading to a compromised chewing function and to sleep disorders (such as obstructive sleep apnea. Thirteen adults with CP underwent bilateral masseter and temporalis neuromuscular electrical stimulation (NMES therapy. The effects on the masticatory muscles and sleep variables were evaluated using electromyography (EMG and polysomnography (PSG, respectively, prior and after 2 months of NMES. EMG consisted of 3 tests in different positions: rest, mouth opening and maximum clenching effort (MCE. EMG values in the rest position were 100% higher than values recorded prior to therapy for all muscles analyzed (p < 0.05; mean mouth opening increased from 38.0 ± 8.0 to 44.0 ± 10.0 cm (p = 0.03. A significant difference in MCE was found only for the right masseter. PSG revealed an improved in the AHI from 7.2±7.0/h to 2.3±1.5/h (p < 0.05; total sleep time improved from 185 min to 250 min (p = 0.04 and minimun SaO2 improved from 83.6 ± 3.0 to 86.4 ± 4.0 (p = 0.04. NMES performed over a two-month period led to improvements in the electrical activity of the masticatory muscles at rest, mouth opening, isometric contraction and sleep variables, including the elimination of obstructive sleep apnea events in patients with CP. Trial registration: ReBEC RBR994XFS http://www.ensaiosclinicos.gov.br.

  6. GH signaling in human adipose and muscle tissue during 'feast and famine': amplification of exercise stimulation following fasting compared to glucose administration.

    Science.gov (United States)

    Vendelbo, Mikkel H; Christensen, Britt; Grønbæk, Solbritt B; Høgild, Morten; Madsen, Michael; Pedersen, Steen B; Jørgensen, Jens O L; Jessen, Niels; Møller, Niels

    2015-09-01

    Fasting and exercise stimulates, whereas glucose suppresses GH secretion, but it is uncertain how these conditions impact GH signaling in peripheral tissues. To test the original 'feast and famine hypothesis' by Rabinowitz and Zierler, according to which the metabolic effects of GH are predominant during fasting, we specifically hypothesized that fasting and exercise act in synergy to increase STAT-5b target gene expression. Eight healthy men were studied on two occasions in relation to a 1 h exercise bout: i) with a concomitant i.v. glucose infusion ('feast') and ii) after a 36 h fast ('famine'). Muscle and fat biopsy specimens were obtained before, immediately after, and 30 min after exercise. GH increased during exercise on both examination days and this effect was amplified by fasting, and free fatty acid (FFA) levels increased after fasting. STAT-5b phosphorylation increased similarly following exercise on both occasions. In adipose tissue, suppressors of cytokine signaling 1 (SOCS1) and SOCS2 were increased after exercise on the fasting day and both fasting and exercise increased cytokine inducible SH2-containing protein (CISH). In muscle, SOCS2 and CISH mRNA were persistently increased after fasting. Muscle SOCS1, SOCS3, and CISH mRNA expression increased, whereas SOCS2 decreased after exercise on both examination days. This study demonstrates that fasting and exercise act in tandem to amplify STAT-5b target gene expression (SOCS and CISH) in adipose and muscle tissue in accordance with the 'feast and famine hypothesis'; the adipose tissue signaling responses, which hitherto have not been scrutinized, may play a particular role in promoting FFA mobilization. © 2015 European Society of Endocrinology.

  7. Results of preoperative electrical stimulation of pelvic floor muscles in the continence status following radical retropubic prostatectomy

    Directory of Open Access Journals (Sweden)

    Carla Elaine Laurienzo

    2013-04-01

    Full Text Available Purpose To evaluate preoperative rectal electrical stimulation in the recovery of urinary continence in patients who undergo radical retropubic prostatectomy. Materials and Methods Patients were divided into 3 randomized groups: control, pelvic exercises, and electrical stimulation. A 1 hour pad-test, the ICIQ-SF, and the SF-36 were performed 1, 3, and 6 months after the surgical procedure. Results Of the 58 patients who were initially included in the study, 9 were excluded due to radiotherapy after surgical intervention, an indwelling urethral catheter for more than 30 days, high surgical risk, loss of follow-up, or incomplete participation in the study routines and spontaneous interruption. Forty-nine patients concluded the study (15 in the control group, 17 in the exercise group, and 17 in the electrical stimulation group. We did not observe any significant difference in the pad test (p > 0.05, the 8 domains of the SF-36, or ICIQ-SF score compared with control groups (control, exercise, and electrical stimulation. Conclusion Preoperative rectal electrical stimulation has no impact on continence status in patients who undergo radical retropubic prostatectomy. There is no difference in the three above mentioned groups with regard to urinary leakage and quality of life.

  8. The impact of neuromuscular electrical stimulation on recovery after intensive, muscle damaging, maximal speed training in professional team sports players.

    Science.gov (United States)

    Taylor, Tom; West, Daniel J; Howatson, Glyn; Jones, Chris; Bracken, Richard M; Love, Thomas D; Cook, Christian J; Swift, Eamon; Baker, Julien S; Kilduff, Liam P

    2015-05-01

    During congested fixture periods in team sports, limited recovery time and increased travel hinder the implementation of many recovery strategies; thus alternative methods are required. We examined the impact of a neuromuscular electrical stimulation device on 24-h recovery from an intensive training session in professional players. Twenty-eight professional rugby and football academy players completed this randomised and counter-balanced study, on 2 occasions, separated by 7 days. After baseline perceived soreness, blood (lactate and creatine kinase) and saliva (testosterone and cortisol) samples were collected, players completed a standardised warm-up and baseline countermovement jumps (jump height). Players then completed 60 m × 50 m maximal sprints, with 5 min recovery between efforts. After completing the sprint session, players wore a neuromuscular electrical stimulation device or remained in normal attire (CON) for 8 h. All measures were repeated immediately, 2 and 24-h post-sprint. Player jump height was reduced from baseline at all time points under both conditions; however, at 24-h neuromuscular electrical stimulation was significantly more recovered (mean±SD; neuromuscular electrical stimulation -3.2±3.2 vs. CON -7.2±3.7%; P0.05). Neuromuscular electrical stimulation improves recovery from intensive training in professional team sports players. This strategy offers an easily applied recovery strategy which may have particular application during sleep and travel. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  9. Role of catechins on ET-1 induced stimulation of PLD and NADPH oxidase activities in pulmonary smooth muscle cells: Determination of the probable mechanism by molecular docking studies.

    Science.gov (United States)

    Chakraborti, Sajal; Sarkar, Jaganmay; Bhuyan, Rajabrata; Chakraborti, Tapati

    2017-12-05

    Treatment of human pulmonary artery smooth muscle cells with ET-1 stimulated PLD and NADPH oxidase activities, which were inhibited upon pretreatment with bosentan (ET-1 receptor antagonist), FIPI (PLD inhibitor), apocynin (NADPH oxidase inhibitor) and EGCG & ECG (catechins having galloyl group), but not EGC & EC (catechins devoid of galloyl group). Herein, we determined the probable mechanism by which the galloyl group containing catechins inhibit ET-1 induced stimulation of PLD activity by molecular docking analyses based on our biochemical studies. ET-1 induced stimulation of PLD activity was inhibited by SecinH3 (inhibitor of cytohesin). Arf-6 and cytohesin-1 were associated in the cell membrane, which was not inhibited by the catechins during ET-1 treatment to the cells. However, EGCG and ECG inhibited binding of GTPγS with Arf-6 even in presence of cytohesin-1. The molecular docking analyses revealed that the galloyl group containing catechins (EGCG/ECG) with cytohesin1-Arf6GDP, but not the non-galloyl-containing catechins (EGC and EC), prevents GDP/GTP exchange in Arf-6 which seems to be an important mechanism for inhibition of ET-1 induced activation of PLD and subsequently increase in NADPH oxidase activities.

  10. Failure of activation of spinal motoneurones after muscle fatigue in healthy subjects studied by transcranial magnetic stimulation

    DEFF Research Database (Denmark)

    Andersen, Birgit; Westlund, Barbro; Krarup, Christian

    2003-01-01

    During a sustained maximal effort a progressive decline in the ability to drive motoneurones (MNs) develops. We used the recently developed triple stimulation technique (TST) to study corticospinal conduction after fatiguing exercise in healthy subjects. This method employs a collision technique....... This points to increased probability of repetitive spinal MN activation during fatigue even if some MNs in the pool failed to discharge. Silent period duration following cortical stimulation lengthened by an average of 55 ms after the contraction and recovered within a time course similar to that of the TST...

  11. Repeated stimulation, inter-stimulus interval and inter-electrode distance alters muscle contractile properties as measured by Tensiomyography.

    Directory of Open Access Journals (Sweden)

    Hannah V Wilson

    Full Text Available The influence of methodological parameters on the measurement of muscle contractile properties using Tensiomyography (TMG has not been published.To investigate the; (1 reliability of stimulus amplitude needed to elicit maximum muscle displacement (Dm, (2 effect of changing inter-stimulus interval on Dm (using a fixed stimulus amplitude and contraction time (Tc, (3 the effect of changing inter-electrode distance on Dm and Tc.Within subject, repeated measures.10 participants for each objective.Dm and Tc of the rectus femoris, measured using TMG.The coefficient of variance (CV and the intra-class correlation (ICC of stimulus amplitude needed to elicit maximum Dm was 5.7% and 0.92 respectively. Dm was higher when using an inter-electrode distance of 7cm compared to 5cm [P = 0.03] and when using an inter-stimulus interval of 10s compared to 30s [P = 0.017]. Further analysis of inter-stimulus interval data, found that during 10 repeated stimuli Tc became faster after the 5th measure when compared to the second measure [P<0.05]. The 30s inter-stimulus interval produced the most stable Tc over 10 measures compared to 10s and 5s respectively.Our data suggest that the stimulus amplitude producing maximum Dm of the rectus femoris is reliable. Inter-electrode distance and inter-stimulus interval can significantly influence Dm and/ or Tc. Our results support the use of a 30s inter-stimulus interval over 10s or 5s. Future studies should determine the influence of methodological parameters on muscle contractile properties in a range of muscles.

  12. Repeated stimulation, inter-stimulus interval and inter-electrode distance alters muscle contractile properties as measured by Tensiomyography

    Science.gov (United States)

    Johnson, Mark I.; Francis, Peter

    2018-01-01

    Context The influence of methodological parameters on the measurement of muscle contractile properties using Tensiomyography (TMG) has not been published. Objective To investigate the; (1) reliability of stimulus amplitude needed to elicit maximum muscle displacement (Dm), (2) effect of changing inter-stimulus interval on Dm (using a fixed stimulus amplitude) and contraction time (Tc), (3) the effect of changing inter-electrode distance on Dm and Tc. Design Within subject, repeated measures. Participants 10 participants for each objective. Main outcome measures Dm and Tc of the rectus femoris, measured using TMG. Results The coefficient of variance (CV) and the intra-class correlation (ICC) of stimulus amplitude needed to elicit maximum Dm was 5.7% and 0.92 respectively. Dm was higher when using an inter-electrode distance of 7cm compared to 5cm [P = 0.03] and when using an inter-stimulus interval of 10s compared to 30s [P = 0.017]. Further analysis of inter-stimulus interval data, found that during 10 repeated stimuli Tc became faster after the 5th measure when compared to the second measure [P<0.05]. The 30s inter-stimulus interval produced the most stable Tc over 10 measures compared to 10s and 5s respectively. Conclusion Our data suggest that the stimulus amplitude producing maximum Dm of the rectus femoris is reliable. Inter-electrode distance and inter-stimulus interval can significantly influence Dm and/ or Tc. Our results support the use of a 30s inter-stimulus interval over 10s or 5s. Future studies should determine the influence of methodological parameters on muscle contractile properties in a range of muscles. PMID:29451885

  13. BeWo cells stimulate smooth muscle cell apoptosis and elastin breakdown in a model of spiral artery transformation

    OpenAIRE

    Harris, L. K.; Keogh, R. J.; Wareing, M.; Baker, P. N.; Cartwright, J. E.; Whitley, G. S.; Aplin, J. D.

    2007-01-01

    BACKGROUND: During pregnancy, extravillous trophoblast invades the uterine wall and enters the spiral arteries. Remodelling ensues, with loss of vascular smooth muscle cells (SMCs) to create high flow, low resistance vessels. Pregnancies complicated by pre-eclampsia are characterized by incomplete arterial remodelling. Endovascular trophoblast is not easily accessible for studies to establish the pathogenesis of pre-eclampsia, so we have developed a model appropriate to carry out mechanistic ...

  14. Changes in forearm muscle temperature alter renal vascular responses to isometric handgrip.

    Science.gov (United States)

    Kuipers, Nathan T; Sauder, Charity L; Kearney, Matthew L; Ray, Chester A

    2007-12-01

    The purpose of the present study was to examine the effect of heating and cooling the forearm muscles on renal vascular responses to ischemic isometric handgrip (IHG). It was hypothesized that heating and cooling the forearm would augment and attenuate, respectively, renal vascular responses to IHG. Renal vascular responses to IHG were studied during forearm heating at 39 degrees C (n = 15, 26 +/- 1 yr) and cooling at 26 degrees C (n = 12, 26 +/- 1 yr). For a control trial, subjects performed the experimental protocol while the forearm was normothermic (approximately 34 degrees C). Muscle temperature (measured by intramuscular probe) was controlled by changing the temperature of water cycling through a water-perfused sleeve. The experimental protocol was as follows: 3 min at baseline, 1 min of ischemia, ischemic IHG to fatigue, and 2 min of postexercise muscle ischemia. At rest, renal artery blood velocity (RBV; Doppler ultrasound) and renal vascular conductance (RVC = RBV/mean arterial blood pressure) were not different between normothermia and the two thermal conditions. During ischemic IHG, there were greater decreases in RBV and RVC in the heating trial. However, RBV and RVC were similar during postexercise muscle ischemia during heating and normothermia. RVC decreased less during cooling than in normothermia while the subjects performed the ischemic IHG protocol. During postexercise muscle ischemia, RVC was greater during cooling than in normothermia. These results indicate that heating augments mechanoreceptor-mediated renal vasoconstriction whereas cooling blunts metaboreceptor-mediated renal vasoconstriction.

  15. Reverse mode Na+/Ca2+ exchange mediated by STIM1 contributes to Ca2+ influx in airway smooth muscle following agonist stimulation

    Directory of Open Access Journals (Sweden)

    Fox Jane

    2010-12-01

    Full Text Available Abstract Background Agonist stimulation of airway smooth muscle (ASM results in IP3 mediated Ca2+ release from the sarcoplasmic reticulum followed by the activation of store operated and receptor operated non-selective cation channels. Activation of these non-selective channels also results in a Na+ influx. This localised increase in Na+ levels can potentially switch the Na+/Ca2+ exchanger into reverse mode and so result in a further influx of Ca2+. The aim of this study was to characterise the expression and physiological function of the Na+/Ca2+ exchanger in cultured human bronchial smooth muscle cells and determine its contribution to agonist induced Ca2+ influx into these cells. Methods The expression profile of NCX (which encodes the Na+/Ca2+ exchanger homologues in cultured human bronchial smooth muscle cells was determined by reverse transcriptase PCR. The functional activity of reverse mode NCX was investigated using a combination of whole cell patch clamp, intracellular Ca2+ measurements and porcine airway contractile analyses. KB-R7943 (an antagonist for reverse mode NCX and target specific siRNA were utilised as tools to inhibit NCX function. Results NCX1 protein was detected in cultured human bronchial smooth muscle cells (HBSMC cells and NCX1.3 was the only mRNA transcript variant detected. A combination of intracellular Na+ loading and addition of extracellular Ca2+ induced an outwardly rectifying current which was augmented following stimulation with histamine. This outwardly rectifying current was inhibited by 10 μM KB-R7943 (an antagonist of reverse mode NCX1 and was reduced in cells incubated with siRNA against NCX1. Interestingly, this outwardly rectifying current was also inhibited following knockdown of STIM1, suggesting for the first time a link between store operated cation entry and NCX1 activation. In addition, 10 μM KB-R7943 inhibited agonist induced changes in cytosolic Ca2+ and induced relaxation of porcine

  16. Alterations of the amplitude of low-frequency fluctuation in healthy subjects with theta-burst stimulation of the cortex of the suprahyoid muscles.

    Science.gov (United States)

    Ruan, Xiuhang; Xu, Guangqing; Gao, Cuihua; Liu, Lingling; Liu, Yanli; Jiang, Lisheng; Chen, Xin; Yu, Shaode; Jiang, Xinqing; Lan, Yue; Wei, Xinhua

    2017-12-04

    Theta burst stimulation (TBS) has emerged as a promising tool for the treatment of swallowing disorders; however, the short-term after-effects of brain activation induced by TBS remain unknown. Here, we measured the changes in spontaneous brain activation using the amplitude of low-frequency fluctuation (ALFF) approach in subjects who underwent different TBS protocols. Sixty right-handed healthy participants (male, n=30; female, n=30; mean age=23.5y) were recruited in this study and randomly assigned to three groups that underwent three different TBS protocols. In group 1, continuous TBS (cTBS) was positioned on the left hemisphere of the suprahyoid muscle cortex. For group 2, intermittent TBS (iTBS) was placed on the left hemisphere of the suprahyoid muscle cortex. Group 3 underwent combined cTBS/iTBS protocols in which iTBS on the right hemisphere was performed immediately after completing cTBS on the left suprahyoid muscle cortex. Compared to pre-TBS, post-cTBS showed decreased ALFF in the anterior cingulate gyrus (BA 32); post-iTBS induced an increase in ALFF in the bilateral precuneus (BA 7); and post-cTBS/iTBS induced a decrease in ALFF in the brainstem, and resulted in increased ALFF in the middle cingulate gyrus (BA 24) as well as the left precentral gyrus (BA 6). Compared the effect of post-TBS protocols, increased ALFF was found in left posterior cerebellum lobe and left inferior parietal lobule (BA 40) (post-cTBS vs post-iTBS), and decreased ALFF exhibited in paracentral lobule (BA 4) (post-iTBS vs post-cTBS/iTBS). These findings indicate that multiple brain areas involved in swallowing regulation after stimulation of TBS over the suprahyoid muscles. cTBS induces decreased after-effects while iTBS results in increased after-effects on spontaneous brain activation. Moreover, iTBS can eliminate the after-effects of cTBS applied on the contralateral swallowing cortex and alter the activity of contralateral motor cortex and brainstem. Our findings provide a

  17. [Effect of Different Stimulating Strength of Electroacupuncture on Gastrointestinal Motility and RhoA/ROCK Signaling in Gastric Antral Smooth Muscle in Diabetic Gastroparesis Rats].

    Science.gov (United States)

    Wu, Xue-Fen; Chen, Xiao-Li; Zheng, Xue-Na; Guo, Xin; Xie, Zhi-Qiang; Liu, Li; Wei, Xin-Ran; Yue, Zeng-Hui

    2018-03-25

    To observe the effect of different strength of electroacupuncture (EA) stimulation on gastrointestinal motility and Ras homolog gene family member (RhoA)/Rho associated coiled-coil forming protein kinase (ROCK) signaling in diabetic gastroparesis (DGP) rats, so as to reveal the underlying mechanisms of EA for improving DGP. Sixty SD rats were randomly and equally divided into blank control, DGP model, weak EA, medium EA, and strong EA groups ( n =12 rats in each). The DGP model was established by intraperitoneal injection of streptozotocin (STZ, 55 mmol/kg, 2%) and high-sugar and high-fat fodder feeding for 8 weeks. EA (0.12, 0.24, 0.36 mA, 20 Hz/100 Hz) was applied to "Zusanli" (ST 36), "Sanyinjiao" (SP 6) and "Liangmen" (ST 21) for 20 min, once daily for 15 successive days. Blood glucose levels were measured weekly with blood glucose meter and blood glucose test paper. Fecal phenol red excretion method was used to display gastric emptying and small intestinal propulsion function. The expression of RhoA protein in the gastric antral smooth muscle tissue was detected by immunohistochemistry and Western blot (WB), separately, and that of ROCK, myosin phosphatase target subunit 1 (MYPT 1) and phosphorylated (p)-MYPT 1 proteins in gastric antrum detected by WB. Compared with the blank control group, the gastric emptying rate and small intestine propulsion rate of the model group were significantly decreased ( P ROCK, MYPT 1 and p-MYPT 1 proteins in the gastric antrum were significantly down-regulated relevant to the control group ( P ROCK, MYPT 1 and p-MYPT 1 proteins were significantly increased in the strong, medium and weak EA stimulation groups ( P ROCK, MYPT 1 and p-MYPT 1 proteins, and obviously superior to the medium stimulation in up-regulating RhoA and MYPT 1 protein levels ( P ROCK, MYPT 1 and p-MYPT 1 proteins ( P ROCK and p-MYPT 1 proteins ( P >0.05). Electroacupuncture stimulation of ST 36-SP 6-ST 21 at 0.12, 0.24 and 0.36 mA can promote the

  18. Muscle glycogenolysis during exercise

    DEFF Research Database (Denmark)

    Richter, Erik; Ruderman, N B; Gavras, H

    1982-01-01

    glycogenolysis during exercise: contractions principally stimulate glycogenolysis early in exercise, and a direct effect of epinephrine on muscle is needed for continued glycogenolysis. In addition, epinephrine increased oxygen consumption and glucose uptake in both resting and electrically stimulated...

  19. The Efficacy of Functional Electrical Stimulation of the Abdominal Muscles in the Treatment of Chronic Constipation in Patients with Multiple Sclerosis: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Christine Singleton

    2016-01-01

    Full Text Available Chronic constipation in patients with multiple sclerosis (MS is common and the current methods of treatment are ineffective in some patients. Anecdotal observations suggest that functional electrical stimulation (FES of the abdominal muscles may be effective in the management of constipation in these patients. Patients and Methods. In this exploratory investigation we studied the effects of FES on the whole gut transit time (WGTT and the colonic transit time (CTT. In addition, we evaluated the treatment effect on the patients’ constipation-related quality of life and on the use of laxatives and the use of manual bowel evacuation. FES was given for 30 minutes twice a day for a period of six weeks. Four female patients were studied. Results. The WGTT and CTT and constipation-related quality of life improved in all patients. The patients’ use of laxatives was reduced. No adverse effects of FES treatment were reported. Conclusion. The findings of this pilot study suggest that FES applied to the abdominal muscles may be an effective treatment modality for severe chronic constipation in patients with MS.

  20. Dihydrotestosterone stimulates amino acid uptake and the expression of LAT2 in mouse skeletal muscle fibres through an ERK1/2-dependent mechanism

    Science.gov (United States)

    Hamdi, M M; Mutungi, G

    2011-01-01

    Abstract Dihydrotestosterone (DHT) has acute/non-genomic actions in adult mammalian skeletal muscles whose physiological functions are still poorly understood. Therefore, the primary aim of this study was to investigate the acute/non-genomic effects of DHT on amino acid uptake as well as the cellular signal transduction events underlying these actions in mouse fast- and slow-twitch skeletal muscle fibre bundles. 14C-Labelled amino acids were used to investigate the effects of DHT and testosterone (T) on amino acid uptake and pharmacological interventions were used to determine the cellular signal transduction events mediating these actions. While T had no effect on the uptake of isoleucine (Ile) and α-methylaminoisobutyric acid (MeAIB) in both fibre types, DHT increased their uptake in the fast-twitch fibre bundles. This effect was reversed by inhibitors of protein translation, the epidermal growth factor receptor (EGFR), system A, system L, mTOR and MEK. However, it was relatively insensitive to inhibitors of transcription, androgen receptors and PI3K/Akt. Additionally, DHT treatment increased the expression of LAT2 and the phosphorylation of the EGFR in the fast-twitch fibre bundles and that of ERK1/2, RSK1/2 and ATF2 in both fibre types. Also, it decreased the phosphorylation of eEF2 and increased the incorporation of Ile into proteins in both fibre types. Most of these effects were reversed by EGFR and MEK inhibitors. From these findings we suggest that another physiological function of the acute/non-genomic actions of DHT in isolated mammalian skeletal muscle fibres is to stimulate amino acid uptake. This effect is mediated through the EGFR and involves the activation of the MAPK pathway and an increase in LAT2 expression. PMID:21606113

  1. Recovery of whisking function promoted by manual stimulation of the vibrissal muscles after facial nerve injury requires insulin-like growth factor 1 (IGF-1).

    Science.gov (United States)

    Kiryakova, S; Söhnchen, J; Grosheva, M; Schuetz, U; Marinova, Ts; Dzhupanova, R; Sinis, N; Hübbers, C U; Skouras, E; Ankerne, J; Fries, J W U; Irintchev, A; Dunlop, S A; Angelov, D N

    2010-04-01

    Recently, we showed that manual stimulation (MS) of denervated vibrissal muscles enhanced functional recovery following facial nerve cut and suture (FFA) by reducing poly-innervation at the neuro-muscular junctions (NMJ). Although the cellular correlates of poly-innervation are established, with terminal Schwann cells (TSC) processes attracting axon sprouts to "bridge" adjacent NMJ, molecular correlates are poorly understood. Since quantitative RT-PCR revealed a rapid increase of IGF-1 mRNA in denervated muscles, we examined the effect of daily MS for 2 months after FFA in IGF-1(+/-) heterozygous mice; controls were wild-type (WT) littermates including intact animals. We quantified vibrissal motor performance and the percentage of NMJ bridged by S100-positive TSC. There were no differences between intact WT and IGF-1(+/-) mice for vibrissal whisking amplitude (48 degrees and 49 degrees ) or the percentage of bridged NMJ (0%). After FFA and handling alone (i.e. no MS) in WT animals, vibrissal whisking amplitude was reduced (60% lower than intact) and the percentage of bridged NMJ increased (42% more than intact). MS improved both the amplitude of vibrissal whisking (not significantly different from intact) and the percentage of bridged NMJ (12% more than intact). After FFA and handling in IGF-1(+/-) mice, the pattern was similar (whisking amplitude 57% lower than intact; proportion of bridged NMJ 42% more than intact). However, MS did not improve outcome (whisking amplitude 47% lower than intact; proportion of bridged NMJ 40% more than intact). We conclude that IGF-I is required to mediate the effects of MS on target muscle reinnervation and recovery of whisking function. Copyright 2010 Elsevier Inc. All rights reserved.

  2. Andrographolide inhibits nuclear factor-κB activation through JNK-Akt-p65 signaling cascade in tumor necrosis factor-α-stimulated vascular smooth muscle cells.

    Science.gov (United States)

    Chen, Yu-Ying; Hsu, Ming-Jen; Hsieh, Cheng-Ying; Lee, Lin-Wen; Chen, Zhih-Cherng; Sheu, Joen-Rong

    2014-01-01

    Critical vascular inflammation leads to vascular dysfunction and cardiovascular diseases, including abdominal aortic aneurysms, hypertension, and atherosclerosis. Andrographolide is the most active and critical constituent isolated from the leaves of Andrographis paniculata, a herbal medicine widely used for treating anti-inflammation in Asia. In this study, we investigated the mechanisms of the inhibitory effects of andrographolide in vascular smooth muscle cells (VSMCs) exposed to a proinflammatory stimulus, tumor necrosis factor-α (TNF-α). Treating TNF-α-stimulated VSMCs with andrographolide suppressed the expression of inducible nitric oxide synthase in a concentration-dependent manner. A reduction in TNF-α-induced c-Jun N-terminal kinase (JNK), Akt, and p65 phosphorylation was observed in andrographolide-treated VSMCs. However, andrographolide affected neither IκBα degradation nor p38 mitogen-activated protein kinase or extracellular signal-regulated kinase 1/2 phosphorylation under these conditions. Both treatment with LY294002, a phosphatidylinositol 3-kinase/Akt inhibitor, and treatment with SP600125, a JNK inhibitor, markedly reversed the andrographolide-mediated inhibition of p65 phosphorylation. In addition, LY294002 and SP600125 both diminished Akt phosphorylation, whereas LY294002 had no effects on JNK phosphorylation. These results collectively suggest that therapeutic interventions using andrographolide can benefit the treatment of vascular inflammatory diseases, and andrographolide-mediated inhibition of NF-κB activity in TNF-α-stimulated VSMCs occurs through the JNK-Akt-p65 signaling cascade, an IκBα-independent mechanism.

  3. Effects of flotation-restricted environmental stimulation technique on stress-related muscle pain: what makes the difference in therapy--attention-placebo or the relaxation response?

    Science.gov (United States)

    Bood, Sven A; Sundequist, Ulf; Kjellgren, Anette; Nordstrom, Gun; Norlander, Torsten

    2005-01-01

    The purpose of the present study was to examine the potential effects of attention-placebo on flotation tank therapy. Flotation-restricted environmental stimulation technique is a method whereby an individual lies in a floating tank and all stimuli are reduced to a minimum. Thirty-two patients were diagnosed as having stress-related muscular pain. In addition, 16 of the participants had received the diagnosis of burnout depression. The patients were treated with flotation-restricted environmental stimulation technique for six weeks. One-half of the patients were also given special attention for 12 weeks (high attention), while the remainder received attention for only six weeks (normal attention). The participants exhibited lowered blood pressure, reduced pain, anxiety, depression, stress and negative affectivity, as well as increased optimism, energy and positive affectivity. The results were largely unaffected by the degree of attention-placebo or diagnosis. It was concluded that flotation therapy is an effective, noninvasive method for treating stress-related pain, and that the method is not more affected by placebo than by other methods currently used in pain treatment. The treatment of both burnout depression and pain related to muscle tension constitutes a major challenge for the patient as well as the care provider, an area in which great gains can be made if the treatment is effective. Flotation therapy may constitute an integral part of such treatment.

  4. Atorvastatin Protects Vascular Smooth Muscle Cells From TGF-β1-Stimulated Calcification by Inducing Autophagy via Suppression of the β-Catenin Pathway

    Directory of Open Access Journals (Sweden)

    Demin Liu

    2014-01-01

    Full Text Available Background: Arterial calcification is a major event in the progression of atherosclerosis. It is reported that statins exhibit various protective effects against vascular smooth muscle cell (VSMC inflammation and proliferation in cardiovascular remodeling. Although statins counteract atherosclerosis, the molecular mechanisms of statins on the calcium release from VSMCs have not been clearly elucidated. Methods: Calcium content of VSMCs was measured using enzyme-linked immunosorbent assay (ELISA. The expression of proteins involved in cellular transdifferentiation was analyzed by western blot. Cell autophagy was measured by fluorescence microscopic analysis for acridine orange staining and transmission electron microscopy analysis. The autophagic inhibitors (3-MA, chloroquine, NH4Cl and bafilomycin A1 and β-catenin inhibitor JW74 were used to assess the effects of atorvastatin on autophagy and the involvement of β-catenin on cell calcification respectively. Furthermore, cell transfection was performed to overexpress β-catenin. Results: In VSMCs, atorvastatin significantly suppressed transforming growth factor-β1 (TGF-β1-stimulated calcification, accompanied by the induction of autophagy. Downregulation of autophagy with autophagic inhibitors significantly suppressed the inhibitory effect of atorvastatin on cell calcification. Moreover, the beneficial effect of atorvastatin on calcification and autophagy was reversed by β-catenin overexpression. Conversely, JW74 supplement enhanced this effect. Conclusion: These data demonstrated that atorvastatin protect VSMC from TGF-β1-stimulated calcification by inducing autophagy through suppression of the β-catenin pathway, identifying autophagy induction might be a therapeutic strategy for use in vascular calcification.

  5. Consumption of whole eggs promotes greater stimulation of postexercise muscle protein synthesis than consumption of isonitrogenous amounts of egg whites in young men.

    Science.gov (United States)

    van Vliet, Stephan; Shy, Evan L; Abou Sawan, Sidney; Beals, Joseph W; West, Daniel Wd; Skinner, Sarah K; Ulanov, Alexander V; Li, Zhong; Paluska, Scott A; Parsons, Carl M; Moore, Daniel R; Burd, Nicholas A

    2017-12-01

    Background: Protein in the diet is commonly ingested from whole foods that contain various macro- and micronutrients. However, the effect of consuming protein within its natural whole-food matrix on postprandial protein metabolism remains understudied in humans. Objective: We aimed to compare the whole-body and muscle protein metabolic responses after the consumption of whole eggs with egg whites during exercise recovery in young men. Design: In crossover trials, 10 resistance-trained men [aged 21 ± 1 y; 88 ± 3 kg; body fat: 16% ± 1% (means ± SEMs)] received primed continuous l-[ ring - 2 H 5 ]phenylalanine and l-[1- 13 C]leucine infusions and performed a single bout of resistance exercise. After exercise, participants consumed intrinsically l-[5,5,5- 2 H 3 ]leucine-labeled whole eggs (18 g protein, 17 g fat) or egg whites (18 g protein, 0 g fat). Repeated blood and muscle biopsy samples were collected to assess whole-body leucine kinetics, intramuscular signaling, and myofibrillar protein synthesis. Results: Plasma appearance rates of protein-derived leucine were more rapid after the consumption of egg whites than after whole eggs ( P = 0.01). Total plasma availability of leucine over the 300-min postprandial period was similar ( P = 0.75) between the ingestion of whole eggs (68% ± 1%) and egg whites (66% ± 2%), with no difference in whole-body net leucine balance ( P = 0.27). Both whole-egg and egg white conditions increased the phosphorylation of mammalian target of rapamycin complex 1, ribosomal protein S6 kinase 1, and eukaryotic translation initiation factor 4E-binding protein 1 during postexercise recovery (all P egg ingestion increased the postexercise myofibrillar protein synthetic response to a greater extent than did the ingestion of egg whites ( P = 0.04). Conclusions: We show that the ingestion of whole eggs immediately after resistance exercise resulted in greater stimulation of myofibrillar protein synthesis than did the ingestion of egg whites

  6. Newton Output Blocking Force under Low-Voltage Stimulation for Carbon Nanotube-Electroactive Polymer Composite Artificial Muscles.

    Science.gov (United States)

    Chen, I-Wen Peter; Yang, Ming-Chia; Yang, Chia-Hui; Zhong, Dai-Xuan; Hsu, Ming-Chun; Chen, YiWen

    2017-02-15

    This is a study on the development of carbon nanotube-based composite actuators using a new ionic liquid-doped electroactive ionic polymer. For scalable production purposes, a simple hot-pressing method was used. Carbon nanotube/ionic liquid-Nafion/carbon nanotube composite films were fabricated that exhibited a large output blocking force and a stable cycling life with low alternating voltage stimuli in air. Of particular interest and importance, a blocking force of 1.5 N was achieved at an applied voltage of 6 V. Operational durability was confirmed by testing in air for over 30 000 cycles (or 43 h). The superior actuation performance of the carbon nanotube/ionic liquid-Nafion/carbon nanotube composite, coupled with easy manufacturability, low driving voltage, and reliable operation, promises great potential for artificial muscle and biomimetic applications.

  7. Endoluminal norepinephrine inhibits smooth muscle activity of the pig pyeloureter by stimulation of beta-adrenoceptors without side effects

    DEFF Research Database (Denmark)

    Mortensen, Jens; Holst, Uffe; Jacobsen, Jørn Skibsted

    2008-01-01

    of pyeloureter and to reveal possible side effects on cardiovascular and renal functions. Renal pelvis was perfused, while pelvic pressure, cardiovascular and renal functional parameters were recorded. In group A, a pelvic pressure increase was examined during pressure flow studies with norepinephrine solutions......It has been demonstrated in pigs that endoluminal administration of norepinephrine reduces the increase in renal pelvic pressure during perfusion. The purposes were to describe concentration-response relationship and receptor mechanism of the effect of norepinephrine on muscle function...... a renal pelvis pressure increase to perfusion in a dose-related way without side effects. Endoluminal norepinephrine is safe in pigs and may be useful under endoscopy of the pyeloureter....

  8. Effects of electric stimulation of the hunger center in the lateral hypothalamus on slow electric activity and spike activity of fundal and antral stomach muscles in rabbits under conditions of hunger and satiation.

    Science.gov (United States)

    Kromin, A A; Zenina, O Yu

    2013-09-01

    In chronic experiments on rabbits, the effect of electric stimulation of the hunger center in the lateral hypothalamus on myoelectric activity of the fundal and antral parts of the stomach was studied under conditions of hunger and satiation in the absence of food. Stimulation of the lateral hypothalamus in rabbits subjected to 24-h food deprivation and in previously fed rabbits produced incessant seeking behavior, which was followed by reorganization of the structure of temporal organization of slow wave electric activity of muscles of the stomach body and antrum specific for hungry and satiated animals. Increased hunger motivation during electric stimulation of the lateral hypothalamus manifested in the structure of temporal organization of slow wave electric activity of the stomach body and antrum muscles in rabbits subjected to 24-h food deprivation in the replacement of bimodal distribution of slow wave periods to a trimodal type typical of 2-day deprivation, while transition from satiation to hunger caused by electric stimulation of the lateral hypothalamus was associated with a shift from monomodal distributions of slow wave periods to a bimodal type typical of 24-h deprivation. Reorganization of the structure of temporal organization of slow wave electric activity of the stomach body and antrum muscles during electric stimulation of the lateral hypothalamus was determined by descending inhibitory influences of food motivational excitation on activity of the myogenic pacemaker of the lesser curvature of the stomach.

  9. Persistent attenuation and enhancement of the earthworm main muscle contraction generator response induced by repeated stimulation of a peripheral neuron

    Directory of Open Access Journals (Sweden)

    Y.C. Chang

    1998-10-01

    Full Text Available Responses evoked in the earthworm, Amynthas hawayanus, main muscle contraction generator M-2 (postsynaptic mechanical-stimulus-sensitive neuron by threshold mechanical stimuli in 2-s intertrial intervals (ITI were used as the control or unconditioned responses (UR. Their attenuation induced by decreasing these intervals in non-associative conditioning and their enhancement induced by associating the unconditioned stimuli (US to a train of short (0.1 s hyperpolarizing electrical substitutive conditioning stimuli (SCS in the Peri-Kästchen (PK neuron were measured in four parameters, i.e., peak numbers (N and amplitude (averaged from 120 responses, sum of these amplitudes (SAMP and the highest peak amplitude (V over a period of 4 min. Persistent attenuation similar to habituation was induced by decreasing the control ITI to 0.5 s and 2.0 s in non-associative conditioning within less than 4 min. Dishabituation was induced by randomly pairing one of these habituated US to an electrical stimulus in the PK neuron. All four parameters of the UR were enhanced by forward (SCS-US, but not backward (US-SCS, association of the US with 25, 100 and 250-Hz trains of SCS with 40-ms interstimulus intervals (ISI for 4 min and persisted for another 4 min after turning off the SCS. The enhancement of these parameters was proportional to the SCS frequencies in the train. No UR was evoked by the SCS when the US was turned off after 4 min of classical conditioning.

  10. Design, synthesis and biological evaluation of novel ring-opened cromakalim analogues with relaxant effects on vascular and respiratory smooth muscles and as stimulators of elastin synthesis.

    Science.gov (United States)

    Bouhedja, Mourad; Peres, Basile; Fhayli, Wassim; Ghandour, Zeinab; Boumendjel, Ahcène; Faury, Gilles; Khelili, Smail

    2018-01-20

    Two new series of ring-opened analogues of cromakalim bearing sulfonylurea moieties (series A: with N-unmethylated sulfonylureas, series B: with N-methylated sulfonylureas) were synthesized and tested as relaxants of vascular and respiratory smooth muscles (rat aorta and trachea, respectively). Ex vivo biological evaluations indicated that the most active compounds, belonging to series B, displayed a marked vasorelaxant activity on endothelium-intact aortic rings and the trachea. A majority of series B compounds exhibited a higher vasorelaxant activity (EC 50  stronger relaxant effects on the trachea than the reference compound cromakalim (EC 50  = 124 μM), in particular compounds B4, B7 and B16 (EC 50   57 μM for all, and EC 50  > 200 μM for a majority of them), but some of them showed an interesting relaxing effect on trachea (i.e. A15 and A33, EC 50  = 30 μM). The most potent compounds of both series, i.e. A15, A33 and B16, tested on aortic rings in the presence of glibenclamide or 80 mM KCl, suggested that they acted as voltage-gated Ca 2+ channel blockers, like verapamil, instead of being ATP-potassium channel activators, as is cromakalim, the parent molecule. Further investigations on cultured vascular smooth muscle cells showed a strong stimulating effect on elastin synthesis, especially compound B16, which was more active at 20 μM than diazoxide, a reference ATP-sensitive potassium channel activator. Taken together, our results show that the N-methylation of the sulfonylurea moieties of ring-opened cromakalim analogues led to new compounds blocking calcium-gated channels, which had a major impact on the arterial and tracheal activities as well as selectivity. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  11. MicroRNA-31 controls phenotypic modulation of human vascular smooth muscle cells by regulating its target gene cellular repressor of E1A-stimulated genes

    International Nuclear Information System (INIS)

    Wang, Jie; Yan, Cheng-Hui; Li, Yang; Xu, Kai; Tian, Xiao-Xiang; Peng, Cheng-Fei; Tao, Jie; Sun, Ming-Yu; Han, Ya-Ling

    2013-01-01

    Phenotypic modulation of vascular smooth muscle cells (VSMCs) plays a critical role in the pathogenesis of a variety of proliferative vascular diseases. The cellular repressor of E1A-stimulated genes (CREG) has been shown to play an important role in phenotypic modulation of VSMCs. However, the mechanism regulating CREG upstream signaling remains unclear. MicroRNAs (miRNAs) have recently been found to play a critical role in cell differentiation via target-gene regulation. This study aimed to identify a miRNA that binds directly to CREG, and may thus be involved in CREG-mediated VSMC phenotypic modulation. Computational analysis indicated that miR-31 bound to the CREG mRNA 3′ untranslated region (3′-UTR). miR-31 was upregulated in quiescent differentiated VSMCs and downregulated in proliferative cells stimulated by platelet-derived growth factor and serum starvation, demonstrating a negative relationship with the VSMC differentiation marker genes, smooth muscle α-actin, calponin and CREG. Using gain-of-function and loss-of-function approaches, CREG and VSMC differentiation marker gene expression levels were shown to be suppressed by a miR-31 mimic, but increased by a miR-31 inhibitor at both protein and mRNA levels. Notably, miR-31 overexpression or inhibition affected luciferase expression driven by the CREG 3′-UTR containing the miR-31 binding site. Furthermore, miR-31-mediated VSMC phenotypic modulation was inhibited in CREG-knockdown human VSMCs. We also determined miR-31 levels in the serum of patients with coronary artery disease (CAD), with or without in stent restenosis and in healthy controls. miR-31 levels were higher in the serum of CAD patients with restenosis compared to CAD patients without restenosis and in healthy controls. In summary, these data demonstrate that miR-31 not only directly binds to its target gene CREG and modulates the VSMC phenotype through this interaction, but also can be an important biomarker in diseases involving VSMC

  12. Andrographolide Inhibits Nuclear Factor-κB Activation through JNK-Akt-p65 Signaling Cascade in Tumor Necrosis Factor-α-Stimulated Vascular Smooth Muscle Cells

    Directory of Open Access Journals (Sweden)

    Yu-Ying Chen

    2014-01-01

    Full Text Available Critical vascular inflammation leads to vascular dysfunction and cardiovascular diseases, including abdominal aortic aneurysms, hypertension, and atherosclerosis. Andrographolide is the most active and critical constituent isolated from the leaves of Andrographis paniculata, a herbal medicine widely used for treating anti-inflammation in Asia. In this study, we investigated the mechanisms of the inhibitory effects of andrographolide in vascular smooth muscle cells (VSMCs exposed to a proinflammatory stimulus, tumor necrosis factor-α (TNF-α. Treating TNF-α-stimulated VSMCs with andrographolide suppressed the expression of inducible nitric oxide synthase in a concentration-dependent manner. A reduction in TNF-α-induced c-Jun N-terminal kinase (JNK, Akt, and p65 phosphorylation was observed in andrographolide-treated VSMCs. However, andrographolide affected neither IκBα degradation nor p38 mitogen-activated protein kinase or extracellular signal-regulated kinase 1/2 phosphorylation under these conditions. Both treatment with LY294002, a phosphatidylinositol 3-kinase/Akt inhibitor, and treatment with SP600125, a JNK inhibitor, markedly reversed the andrographolide-mediated inhibition of p65 phosphorylation. In addition, LY294002 and SP600125 both diminished Akt phosphorylation, whereas LY294002 had no effects on JNK phosphorylation. These results collectively suggest that therapeutic interventions using andrographolide can benefit the treatment of vascular inflammatory diseases, and andrographolide-mediated inhibition of NF-κB activity in TNF-α-stimulated VSMCs occurs through the JNK-Akt-p65 signaling cascade, an IκBα-independent mechanism.

  13. Effect of bradykinin antagonists on bradykinin-induced plasma extravasation, venoconstriction, prostaglandin E2 release, nociceptor stimulation and contraction of the iris sphincter muscle in the rabbit.

    Science.gov (United States)

    Griesbacher, T.; Lembeck, F.

    1987-01-01

    1 The inhibition of the bradykinin-induced plasma extravasation by six bradykinin (Bk) antagonists was tested on rabbit skin. All of them showed inhibitory effects without an agonistic action in the does used. B4310 (Lys-Lys-3-Hyp-5,8-Thi-7-DPhe-Bk) was the most active antagonist and was therefore used in the subsequent experiments. 2 B4310 (5-500 nM) antagonized the bradykinin-induced reduction of the venous outflow from the rabbit isolated ear in dose-dependent manner without affecting the arterial vasoconstriction induced by angiotensin II. 3 The bradykinin-induced release of prostaglandin E2 (PGE2) from the perfused rabbit ear was reduced by 63% when B4310 (800 nM) was infused before, during and after the bradykinin injection. 4 Bradykinin was injected into the ear artery of anaesthetized rabbits and the reflex hypotensive response was used as indicator of the nociception. The response was antagonized by a local infusion of B4310 (50 and 500 nM). The antagonism was dose-dependent and reversible. The parallel shift of the dose-response curve to bradykinin suggests a competitive inhibition. However, B4310 did not antagonize acetylcholine-induced nociceptor stimulation. 5 B4310 inhibited bradykinin-induced stimulation of the trigeminal nerve which results in a substance P-mediated contraction of the iris sphincter muscle. A pA2 of 7.59 was calculated. B4310 did not inhibit capsaicin-induced contractions. 6 It is concluded that B4310 inhibits specifically five different actions of bradykinin which are related to its possible pathophysiological role. PMID:3479223

  14. Electrical Stimulation During Gait Promotes Increase of Muscle Cross-sectional Area in Quadriplegics: A Preliminary Study

    Science.gov (United States)

    Cliquet, Alberto; Rondina, Jane Maryan; Cendes, Fernando

    2008-01-01

    Increases in muscular cross-sectional area (CSA) occur in quadriplegics after training, but the effects of neuromuscular electrical stimulation (NMES) along with training are unknown. Thus, we addressed two questions: (1) Does NMES during treadmill gait training increase the quadriceps CSA in complete quadriplegics?; and (2) Is treadmill gait training alone enough to observe an increase in CSA? Fifteen quadriplegics were divided into gait (n = 8) and control (n = 7) groups. The gait group performed training with NMES for 6 months twice a week for 20 minutes each time. After 6 months of traditional therapy, the control group received the same gait training protocol but without NMES for an additional 6 months. Axial images of the thigh were acquired at the beginning of the study, at 6 months (for both groups), and at 12 months for the control group to determine the average quadriceps CSA. After 6 months, there was an increase of CSA in the gait group (from 49.8 ± 9.4 cm2 to 57.3 ± 10.3 cm2), but not in the control group (from 43.6 ± 7.6 cm2 to 41.8 ± 8.4 cm2). After another 6 months of gait without NMES in the control group, the CSA did not change (from 41.8 ± 8.4 cm2 to 41.7 ± 7.9 cm2). The increase in quadriceps CSA after gait training in patients with chronic complete quadriplegia appears associated with NMES. PMID:18791775

  15. Dexterous Control of Seven Functional Hand Movements Using Cortically-Controlled Transcutaneous Muscle Stimulation in a Person With Tetraplegia

    Directory of Open Access Journals (Sweden)

    Samuel C. Colachis

    2018-04-01

    Full Text Available Individuals with tetraplegia identify restoration of hand function as a critical, unmet need to regain their independence and improve quality of life. Brain-Computer Interface (BCI-controlled Functional Electrical Stimulation (FES technology addresses this need by reconnecting the brain with paralyzed limbs to restore function. In this study, we quantified performance of an intuitive, cortically-controlled, transcutaneous FES system on standardized object manipulation tasks from the Grasp and Release Test (GRT. We found that a tetraplegic individual could use the system to control up to seven functional hand movements, each with >95% individual accuracy. He was able to select one movement from the possible seven movements available to him and use it to appropriately manipulate all GRT objects in real-time using naturalistic grasps. With the use of the system, the participant not only improved his GRT performance over his baseline, demonstrating an increase in number of transfers for all objects except the Block, but also significantly improved transfer times for the heaviest objects (videocassette (VHS, Can. Analysis of underlying motor cortex neural representations associated with the hand grasp states revealed an overlap or non-separability in neural activation patterns for similarly shaped objects that affected BCI-FES performance. These results suggest that motor cortex neural representations for functional grips are likely more related to hand shape and force required to hold objects, rather than to the objects themselves. These results, demonstrating multiple, naturalistic functional hand movements with the BCI-FES, constitute a further step toward translating BCI-FES technologies from research devices to clinical neuroprosthetics.

  16. Inhibitory effects of epigallocatechin-3-O-gallate on serum-stimulated rat aortic smooth muscle cells via nuclear factor-κB down-modulation

    International Nuclear Information System (INIS)

    Han, Dong-Wook; Lim, Hye Ryeon; Baek, Hyun Sook; Lee, Mi Hee; Lee, Seung Jin; Hyon, Suong-Hyu; Park, Jong-Chul

    2006-01-01

    The abnormal growth of vascular smooth muscle cells (VSMCs) plays an important role in vascular diseases, including atherosclerosis and restenosis after angioplasty. Although (-)-epigallocatechin-3-O-gallate (EGCG) has antiproliferative effects on various cells, relatively a little is known about precise mechanisms of the inhibitory effects of EGCG on SMCs. In this study, the inhibitory effects of EGCG on attachment, proliferation, migration, and cell cycle of rat aortic SMCs (RASMCs) with serum stimulation were investigated. Also, the involvement of nuclear factor-κB (NF-κB) during these inhibitions by EGCG was examined. EGCG treatment resulted in significant (p < 0.05) inhibition in attachment and proliferation of RASMCs induced by serum. While non-treated RASMCs migrated into denuded area in response to serum and showed essentially complete closure after 36 h, EGCG-treated cells covered only 31% of the area even after 48 h of incubation. Furthermore, EGCG treatment resulted in an appreciable cell cycle arrest at both G0/G1- and G2/M-phases. The immunoblot analysis revealed that the constitutive expression of NF-κB/p65 nuclear protein in RASMCs was lowered by EGCG in both the cytosol and the nucleus in a dose-dependent manner. These results suggest that the EGCG-caused inhibitory effects on RASMCs may be mediated through NF-κB down-modulation

  17. Effects of training programs based on ipsilateral voluntary and stimulated contractions on muscle strength and monopedal postural control of the contralateral limb.

    Science.gov (United States)

    Kadri, Mohamed Abdelhafid; Noé, Frederic; Nouar, Merbouha Boulahbel; Paillard, Thierry

    2017-09-01

    To compare the effects of unilateral strength training by stimulated and voluntary contractions on muscle strength and monopedal postural control of the contralateral limb. 36 non-active healthy male subjects were recruited and split randomly into three groups. Two groups of 12 subjects took part in a strength-training program (3 sessions a week over 8 weeks) comprising 43 contractions of the quadriceps femoris of the ipsilateral limb (at 20% of the MVC). One group carried out voluntary contractions exclusively (VOL group), while the other group benefited exclusively from electro-induced contractions (NMES group). The other 12 subjects formed the control (CON) group. Assessments of MVC and monopedal postural control in static and dynamic postural tasks were performed with the ipsilateral (ISPI) and contralateral (CONTRA) limbs before (PRE) and after (POST) completion of the training program. After the training program, the MVC of the IPSI and CONTRA limbs increased similarly for both experimental groups (VOL and NMES). There were no significant improvements of monopedal postural control for the IPSI or CONTRA limbs in either the VOL or NMES experimental group. No change was observed for the CON group over the protocol period. The purposed training program with NMES vs VOL contractions induced strength gains but did not permit any improvement of contralateral monopedal postural control in healthy young subjects. This has potential for therapeutic application and allows clinicians to focus their training programs on dynamic and poly-articular exercises to improve the postural control in young subjects.

  18. Uric acid stimulates proliferative pathways in vascular smooth muscle cells through the activation of p38 MAPK, p44/42 MAPK and PDGFRβ.

    Science.gov (United States)

    Kırça, M; Oğuz, N; Çetin, A; Uzuner, F; Yeşilkaya, A

    2017-04-01

    Hyperuricemia and angiotensin II (Ang II) may have a pathogenetic role in the development of hypertension and atherosclerosis as well as cardiovascular disease (CVD) and its prognosis. The purpose of this study was to investigate whether uric acid can induce proliferative pathways of vascular smooth muscle cell (VSMC) that are thought to be responsible for the development of CVD. The phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK), p44/42 mitogen-activated protein kinase (p44/42 MAPK) and platelet-derived growth factor receptor β (PDGFRβ) was measured by Elisa and Western blot techniques to determine the activation of proliferative pathways in primary cultured VSMCs from rat aorta. Results demonstrated that uric acid can stimulate p38 MAPK, p44/42 MAPK and PDGFRβ phosphorylation in a time- and concentration-dependent manner. Furthermore, treatment of VSMCs with the angiotensin II type I receptor (AT1R) inhibitor losartan suppressed p38 MAPK and p44/42 MAPK induction by uric acid. The stimulatory effect of uric acid on p38 MAPK was higher compared to that of Ang II. The results of this study show for the first time that uric acid-induced PDGFRβ phosphorylation plays a crucial role in the development of CVDs and that elevated uric acid levels could be a potential therapeutical target in CVD patients.

  19. Stimulated echo diffusion tensor imaging and SPAIR T2 -weighted imaging in chronic exertional compartment syndrome of the lower leg muscles.

    Science.gov (United States)

    Sigmund, Eric E; Sui, Dabang; Ukpebor, Obehi; Baete, Steven; Fieremans, Els; Babb, James S; Mechlin, Michael; Liu, Kecheng; Kwon, Jane; McGorty, KellyAnne; Hodnett, Philip A; Bencardino, Jenny

    2013-11-01

    To evaluate the performance of diffusion tensor imaging (DTI) in the evaluation of chronic exertional compartment syndrome (CECS) as compared to T2 -weighted (T2w) imaging. Using an Institutional Review Board (IRB)-approved, Health Insurance Portability and Accountability Act (HIPAA)-compliant protocol, spectral adiabatic inversion recovery (SPAIR) T2w imaging and stimulated echo DTI were applied to eight healthy volunteers and 14 suspected CECS patients before and after exertion. Longitudinal and transverse diffusion eigenvalues, mean diffusivity (MD), and fractional anisotropy (FA) were measured in seven calf muscle compartments, which in patients were classified by their response on T2w: normal (20% change). Mixed model analysis of variance compared subject groups and compartments in terms of response factors (post/pre-exercise ratios) of DTI parameters. All diffusivities significantly increased (P DTI shows promise as an ancillary imaging method in the diagnosis and understanding of the pathophysiology in CECS. Future studies may explore its utility in predicting response to treatment. Copyright © 2013 Wiley Periodicals, Inc.

  20. Evoked Electromyographically Controlled Electrical Stimulation

    Directory of Open Access Journals (Sweden)

    Mitsuhiro Hayashibe

    2016-07-01

    Full Text Available Time-variant muscle responses under electrical stimulation (ES are often problematic for all the applications of neuroprosthetic muscle control. This situation limits the range of ES usage in relevant areas, mainly due to muscle fatigue and also to changes in stimulation electrode contact conditions, especially in transcutaneous ES. Surface electrodes are still the most widely used in noninvasive applications.Electrical field variations caused by changes in the stimulation contact condition markedly affect the resulting total muscle activation levels. Fatigue phenomena under functional electrical stimulation (FES are also well known source of time-varying characteristics coming from muscle response under ES. Therefore it is essential to monitor the actual muscle state and assess the expected muscle response by ES so as to improve the current ES system in favour of adaptive muscle-response-aware FES control. To deal with this issue, we have been studying a novel control technique using evoked electromyography (eEMG signals to compensate for these muscle time-variances under ES for stable neuroprosthetic muscle control. In this perspective article, I overview the background of this topic and highlight important points to be aware of when using ES to induce the desired muscle activation regardless of the time-variance. I also demonstrate how to deal with the common critical problem of ES to move toward robust neuroprosthetic muscle control with the Evoked Electromyographically Controlled Electrical Stimulation paradigm.

  1. Inspiratory Muscle Training and Functional Electrical Stimulation for Treatment of Heart Failure With Preserved Ejection Fraction: The TRAINING-HF Trial.

    Science.gov (United States)

    Palau, Patricia; Domínguez, Eloy; López, Laura; Ramón, José María; Heredia, Raquel; González, Jessika; Santas, Enrique; Bodí, Vicent; Miñana, Gema; Valero, Ernesto; Mollar, Anna; Bertomeu González, Vicente; Chorro, Francisco J; Sanchis, Juan; Lupón, Josep; Bayés-Genís, Antoni; Núñez, Julio

    2018-03-16

    Despite the prevalence of heart failure with preserved ejection fraction (HFpEF), there is currently no evidence-based effective therapy for this disease. This study sought to evaluate whether inspiratory muscle training (IMT), functional electrical stimulation (FES), or a combination of both (IMT + FES) improves 12- and 24-week exercise capacity as well as left ventricular diastolic function, biomarker profile, and quality of life in HFpEF. A total of 61 stable symptomatic patients (New York Heart Association II-III) with HFpEF were randomized (1:1:1:1) to receive a 12-week program of IMT, FES, or IMT + FES vs usual care. The primary endpoint of the study was to evaluate change in peak exercise oxygen uptake at 12 and 24 weeks. Secondary endpoints were changes in quality of life, echocardiogram parameters, and prognostic biomarkers. We used a mixed-effects model for repeated-measures to compare endpoints changes. Mean age and peak exercise oxygen uptake were 74 ± 9 years and 9.9 ± 2.5mL/min/kg, respectively. The proportion of women was 58%. At 12 weeks, the mean increase in peak exercise oxygen uptake (mL/kg/min) compared with usual care was 2.98, 2.93, and 2.47 for IMT, FES, and IMT + FES, respectively (P < .001) and this beneficial effect persisted after 6 months (1.95, 2.08, and 1.56; P < .001). Significant increases in quality of life scores were found at 12 weeks (P < .001). No other changes were found. In HFpEF patients with low aerobic capacity, IMT and FES were associated with a significant improvement in exercise capacity and quality of life. This trial was registered at ClinicalTrials.gov (Identifier: NCT02638961).. Copyright © 2018 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

  2. AMPK-α2 is involved in exercise training-induced adaptations in insulin-stimulated metabolism in skeletal muscle following high-fat diet.

    Science.gov (United States)

    Abbott, Marcia J; Turcotte, Lorraine P

    2014-10-15

    AMP-activated protein kinase (AMPK) has been studied extensively and postulated to be a target for the treatment and/or prevention of metabolic disorders such as insulin resistance. Exercise training has been deemed a beneficial treatment for obesity and insulin resistance. Furthermore, exercise is a feasible method to combat high-fat diet (HFD)-induced alterations in insulin sensitivity. The purpose of this study was to determine whether AMPK-α2 activity is required to gain beneficial effects of exercise training with high-fat feeding. Wild-type (WT) and AMPK-α2 dominant-negative (DN) male mice were fed standard diet (SD), underwent voluntary wheel running (TR), fed HFD, or trained with HFD (TR + HFD). By week 6, TR, irrespective of genotype, decreased blood glucose and increased citrate synthase activity in both diet groups and decreased insulin levels in HFD groups. Hindlimb perfusions were performed, and, in WT mice with SD, TR increased insulin-mediated palmitate uptake (76.7%) and oxidation (>2-fold). These training-induced changes were not observed in the DN mice. With HFD, TR decreased palmitate oxidation (61-64%) in both WT and DN and increased palmitate uptake (112%) in the WT with no effects on palmitate uptake in the DN. With SD, TR increased ERK1/2 and JNK1/2 phosphorylation, regardless of genotype. With HFD, TR reduced JNK1/2 phosphorylation, regardless of genotype, carnitine palmitoyltransferase 1 expression in WT, and CD36 expression in both DN and WT. These data suggest that low AMPK-α2 signaling disrupts, in part, the exercise training-induced adaptations in insulin-stimulated metabolism in skeletal muscle following HFD. Copyright © 2014 the American Physiological Society.

  3. Effect of transcutaneous electrical muscle stimulation and passive cycling movements on blood pressure and removal of urea and phosphate during hemodialysis.

    Science.gov (United States)

    Farese, Stefan; Budmiger, Raphael; Aregger, Fabienne; Bergmann, Ivo; Frey, Felix J; Uehlinger, Dominik E

    2008-10-01

    Intradialytic exercise has been described to improve blood pressure stability and dialysis efficacy. However, comorbid conditions in the dialysis population often preclude the widespread use of active intradialytic exercise. Therefore, we investigated the effect of intradialytic transcutaneous muscle stimulation (TEMS) and passive cycling movements (PCMs) on blood pressure and dialysis efficacy in patients. Prospective, controlled, randomized, crossover investigation. Ten patients were randomly allocated to TEMS, PCMs, or no intervention (NI) for 9 consecutive dialysis sessions. Participants were studied with NI, PCMs using a motor-driven ergometer, and bilateral TEMS of the leg musculature. Individual dialysis prescriptions were unchanged during the investigation. The effect of TEMS and PCMs on blood pressure and dialysis efficacy in patients was assessed. Mean blood pressure increased from 121/64 +/- 21/15 mm Hg with NI to 132/69 +/- 21/15 mm Hg (P TEMS. Urea and phosphate removal during dialysis were significantly (P TEMS (19.4 +/- 3.7 g/dialysis and 1,197 +/- 265 mg/dialysis) or PCMs (20.1 +/- 3.4 g/dialysis and 1,172 +/- 315 mg/dialysis) than with NI (15.1 +/- 3.9 g/dialysis and 895 +/- 202 mg/dialysis). Body weight, ultrafiltration, Kt/V, and increases in hemoglobin and albumin levels during dialysis did not differ among the NI, PCMs, and TEMS groups. The study design does not allow extension of the findings to prolonged treatment. Future studies during longer observation periods will have to prove the persistence of these acute findings. Both TEMS and PCMs deserve future investigations in dialysis patients because they increase intradialytic blood pressure and facilitate urea and phosphate removal when applied short term.

  4. Estimulação elétrica neuromuscular em cães com atrofia muscular induzida Neuromuscular electric stimulation in dogs with induced muscle atrophy

    Directory of Open Access Journals (Sweden)

    C. Pelizzari

    2008-02-01

    Full Text Available Empregou-se a estimulação elétrica neuromuscular (EENM de baixa freqüência no músculo quadríceps femoral de cães com atrofia induzida e avaliou-se a ocorrência de ganho de massa nessa musculatura. Foram utilizados oito cães com pesos entre 15 e 30kg, distribuídos aleatoriamente em dois grupos denominados de I ou controle e II ou tratado. A articulação femorotibiopatelar esquerda foi imobilizada por 30 dias pelo método de transfixação percutânea tipo II, com retirada de aparelho de imobilização após esse período. Decorridas 48 horas da remoção, foi realizada a EENM nos cães do grupo II, cinco vezes por semana, com intervalo de 24 horas cada sessão, pelo período de 60 dias. Foram avaliadas a circunferência da coxa, a goniometria do joelho, a análise clínica da marcha, as enzimas creatina-quinase (CK e aspartato-amino-transferase (AST e a morfometria das fibras musculares em cortes transversais do músculo vasto lateral colhido mediante biópsia muscular. A EENM foi empregada no músculo quadríceps femoral na freqüência de 50Hz, duração de pulso de 300 milisegundos e relação de tempo on/off de 1:2. Quanto à morfometria das fibras do músculo vasto lateral, no grupo tratado houve aumento significativo (PLow frequency neuromuscular electrical stimulation (NMES was used on the femoral quadriceps of dogs with induced muscular atrophy and the occurrence of gain in mass in these muscles was evaluated. Eight dogs from 15 to 30kg were randomly distributed in two groups named I, or control; and II, or treated. For the induction of muscular atrophy, the left femoral-tibial-patellar joint was immobilized for 30 days by percutaneous transfixation type II. After 30 days, the immobilization device was removed. The NMES treatment began 48 hours after the removal of the immobilization device of the dogs of group II, and it was carried out five times per week with an interval of 24 hours between each session, for 60 days. The

  5. Comparative effect of a 1 h session of electrical muscle stimulation and walking activity on energy expenditure and substrate oxidation in obese subjects.

    Science.gov (United States)

    Grosset, Jean-François; Crowe, Louis; De Vito, Giuseppe; O'Shea, Donal; Caulfield, Brian

    2013-01-01

    It has previously been shown that low-frequency neuromuscular electrical stimulation (NMES) techniques can induce increases in energy expenditure similar to those associated with exercise. This study investigated the metabolic and cardiovascular effects of a 1 h session of lower limb NMES and compared cardiovascular response with that observed during walking in nine obese subjects (three males) (age = 43.8 ± 3.0 years; body mass index (BMI) = 41.5 ± 1.8 kg/m(2)). The NMES protocol consisted of delivering a complex pulse pattern to the thigh muscles for 1 h. The walking test consisted of five 4-min bouts starting at 2 km/h with 1 km/h increments up to 6 km/h. In both tests, an open-circuit gas analyser was used to assess O(2) consumption ([Formula: see text]O(2)), CO(2) production ([Formula: see text]CO(2)), respiratory exchange ratio (RER), and heart rate (HR). Rates of fat oxidation (RFO) and carbohydrate oxidation (CHO) were estimated by indirect calorimetry. One hour of NMES significantly increased [Formula: see text]O(2), HR, RER, and mean energy expenditure compared with resting values, reaching 8.7 ± 1.3 mL·min(-2)·kg(-1) (47% of [Formula: see text]O(2peak)), 114.8 ± 7.5 bpm, 0.95, and 318.5 ± 64.3 kcal/h, respectively. CHO, but not RFO, increased during 1 h of NMES. With NMES, CHO was greater and RFO was less than at all walking speeds except 6 km/h. Lactate also increased more with NMES, to 3.5 ± 0.7 mmol versus a maximum of 1.5 ± 0.3 mmol with the walking protocol. These results suggest that NMES can be used in an obese population to induce an effective cardiovascular exercise response. In fact, the observed increase in energy expenditure induced by 1 h of NMES is clinically important and comparable with that recommended in weight management programs.

  6. Impact of pelvic floor muscle training on sexual function of women with urinary incontinence and a comparison of electrical stimulation versus standard treatment (IPSU trial): a randomised controlled trial.

    Science.gov (United States)

    Jha, Swati; Walters, Stephen J; Bortolami, Oscar; Dixon, Simon; Alshreef, Abualbishr

    2018-03-01

    To evaluate the clinical and cost-effectiveness of electric stimulation plus standard pelvic floor muscle training compared to standard pelvic floor muscle training alone in women with urinary incontinence and sexual dysfunction. Single centre two arm parallel group randomised controlled trial conducted in a Teaching hospital in England. Participants were women presenting with urinary incontinence and sexual dysfunction. The interventions compared were electric stimulation versus standard pelvic floor muscle training. included Prolapse and Incontinence Sexual function Questionnaire (PISQ) physical function dimension at post-treatment (primary); other dimensions of PISQ, SF-36; EQ-5D, EPAQ, resource use, adverse events and cost-effectiveness (secondary outcomes). 114 women were randomised (Intervention n=57; Control group n=57). 64/114 (56%). had valid primary outcome data at follow-up (Intervention 30; Control 34). The mean PISQ-PF dimension scores at follow-up were 33.1 (SD 5.5) and 32.3 (SD 5.2) for the Intervention and Control groups respectively; with the Control group having a higher (better) score. After adjusting for baseline score, BMI, menopausal status, time from randomisation and baseline oxford scale score the mean difference was -1.0 (95% CI: -4.0 to 1.9; P=0.474). There was no differences between the groups in any of the secondary outcomes at follow-up. Within this study, the use of electrical stimulation was cost-effective with very small incremental costs and quality adjusted life years (QALYs). In women presenting with urinary incontinence in conjunction with sexual dysfunction, physiotherapy is beneficial to improve overall sexual function. However no specific form of physiotherapy is beneficial over another. Trial registration ISRCTN09586238. Copyright © 2017 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

  7. Electrical stimulation in dysphagia treatment: a justified controversy?

    NARCIS (Netherlands)

    Bogaardt, H. C. A.

    2008-01-01

    Electrical stimulation in dysphagia treatment: a justified controversy? Neuromuscular electrostimulation (LAMES) is a method for stimulating muscles with short electrical pulses. Neuromuscular electrostimulation is frequently used in physiotherapy to strengthen healthy muscles (as in sports

  8. Combined use of bone marrow-derived mesenchymal stromal cells (BM-MSCs) and platelet rich plasma (PRP) stimulates proliferation and differentiation of myoblasts in vitro: new therapeutic perspectives for skeletal muscle repair/regeneration.

    Science.gov (United States)

    Sassoli, Chiara; Vallone, Larissa; Tani, Alessia; Chellini, Flaminia; Nosi, Daniele; Zecchi-Orlandini, Sandra

    2018-02-05

    Satellite cell-mediated skeletal muscle repair/regeneration is compromised in cases of extended damage. Bone marrow mesenchymal stromal cells (BM-MSCs) hold promise for muscle healing but some criticisms hamper their clinical application, including the need to avoid animal serum contamination for expansion and the scarce survival after transplant. In this context, platelet-rich plasma (PRP) could offer advantages. Here, we compare the effects of PRP or standard culture media on C2C12 myoblast, satellite cell and BM-MSC viability, survival, proliferation and myogenic differentiation and evaluate PRP/BM-MSC combination effects in promoting myogenic differentiation. PRP induced an increase of mitochondrial activity and Ki67 expression comparable or even greater than that elicited by standard media and promoted AKT signaling activation in myoblasts and BM-MSCs and Notch-1 pathway activation in BM-MSCs. It stimulated MyoD, myogenin, α-sarcomeric actin and MMP-2 expression in myoblasts and satellite cell activation. Notably, PRP/BM-MSC combination was more effective than PRP alone. We found that BM-MSCs influenced myoblast responses through a paracrine activation of AKT signaling, contributing to shed light on BM-MSC action mechanisms. Our results suggest that PRP represents a good serum substitute for BM-MSC manipulation in vitro and could be beneficial towards transplanted cells in vivo. Moreover, it might influence muscle resident progenitors' fate, thus favoring the endogenous repair/regeneration mechanisms. Finally, within the limitations of an in vitro experimentation, this study provides an experimental background for considering the PRP/BM-MSC combination as a potential therapeutic tool for skeletal muscle damage, combining the beneficial effects of BM-MSCs and PRP on muscle tissue, while potentiating BM-MSC functionality.

  9. Neural adaptations to electrical stimulation strength training

    NARCIS (Netherlands)

    Hortobagyi, Tibor; Maffiuletti, Nicola A.

    2011-01-01

    This review provides evidence for the hypothesis that electrostimulation strength training (EST) increases the force of a maximal voluntary contraction (MVC) through neural adaptations in healthy skeletal muscle. Although electrical stimulation and voluntary effort activate muscle differently, there

  10. Acute effects of high-frequency microfocal vibratory stimulation on the H reflex of the soleus muscle. A double-blind study in healthy subjects.

    Science.gov (United States)

    Alfonsi, Enrico; Paone, Paolo; Tassorelli, Cristina; De Icco, Roberto; Moglia, Arrigo; Alvisi, Elena; Marchetta, Lucky; Fresia, Mauro; Montini, Alessandra; Calabrese, Marzia; Versiglia, Vittorio; Sandrini, Giorgio

    2015-01-01

    This study in healthy subjects examined the effects of a system delivering focal microvibrations at high frequency (Equistasi®) on tonic vibration stimulus (TVS)-induced inhibition of the soleus muscle H reflex. Highfrequency microvibrations significantly increased the inhibitory effect of TVS on the H reflex for up to three minutes. Moreover, Equistasi® also significantly reduced alpha-motoneuron excitability, as indicated by the changes in the ratio between the maximumamplitude H reflex (Hmax reflex) and the maximumamplitude muscle response (Mmax response); this effect was due to reduction of the amplitude of the H reflex because the amplitude of muscle response remained unchanged. The present findings indicate that Equistasi® has a modulatory effect on proprioceptive reflex circuits. Therefore, Equistasi® might interfere with some mechanisms involved in both physiological and pathophysiological control of movement and of posture.

  11. 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...

  12. Zinc stimulates glucose oxidation and glycemic control by modulating the insulin signaling pathway in human and mouse skeletal muscle cell lines.

    Science.gov (United States)

    Norouzi, Shaghayegh; Adulcikas, John; Sohal, Sukhwinder Singh; Myers, Stephen

    2018-01-01

    Zinc is a metal ion that is an essential cell signaling molecule. Highlighting this, zinc is an insulin mimetic, activating cellular pathways that regulate cellular homeostasis and physiological responses. Previous studies have linked dysfunctional zinc signaling with several disease states including cancer, obesity, cardiovascular disease and type 2 diabetes. The present study evaluated the insulin-like effects of zinc on cell signaling molecules including tyrosine, PRSA40, Akt, ERK1/2, SHP-2, GSK-3β and p38, and glucose oxidation in human and mouse skeletal muscle cells. Insulin and zinc independently led to the phosphorylation of these proteins over a 60-minute time course in both mouse and human skeletal muscle cells. Similarly, utilizing a protein array we identified that zinc could active the phosphorylation of p38, ERK1/2 and GSK-3B in human and ERK1/2 and GSK-3B in mouse skeletal muscle cells. Glucose oxidation assays were performed on skeletal muscle cells treated with insulin, zinc, or a combination of both and resulted in a significant induction of glucose consumption in mouse (pzinc alone. Insulin, as expected, increased glucose oxidation in mouse (pzinc and insulin did not augment glucose consumption in these cells. Zinc acts as an insulin mimetic, activating key molecules implicated in cell signaling to maintain glucose homeostasis in mouse and human skeletal muscle cells. Zinc is an important metal ion implicated in several biological processes. The role of zinc as an insulin memetic in activating key signaling molecules involved in glucose homeostasis could provide opportunities to utilize this ion therapeutically in treating disorders associated with dysfunctional zinc signaling.

  13. The origin of activity in the biceps brachii muscle during voluntary contractions of the contralateral elbow flexor muscles

    NARCIS (Netherlands)

    Zijdewind, Inge; Butler, Jane E.; Gandevia, Simon C.; Taylor, Janet L.

    During strong voluntary contractions, activity is not restricted to the target muscles. Other muscles, including contralateral muscles, often contract. We used transcranial magnetic stimulation (TMS) to analyse the origin of these unintended contralateral contractions (termed "associated"

  14. Proteomics of Skeletal Muscle

    DEFF Research Database (Denmark)

    Deshmukh, Atul

    2016-01-01

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

  15. Multielectrode intrafascicular and extraneural stimulation

    NARCIS (Netherlands)

    Veltink, Petrus H.; van Alste, Jan A.; Boom, H.B.K.

    1989-01-01

    The relationship between nerve stimulation, pulse amplitude and isometric muscle force was measured to investigate recruitment of motor units. Force addition experiments were performed to obtain insight in the intersection of motor unit groups recruited by different electrodes. Intrafascicular and

  16. Exercise training favors increased insulin-stimulated glucose uptake in skeletal muscle in contrast to adipose tissue: a randomized study using FDG PET imaging

    DEFF Research Database (Denmark)

    Reichkendler, M. H.; Auerbach, P.; Rosenkilde, M.

    2013-01-01

    abdominal SAT compared with CON but not in either intra- or retroperitoneal VAT. Total adipose tissue mass decreased in both exercise groups, and the decrease was distributed equally among subcutaneous and intra-abdominal depots. In conclusion, aerobic exercise training increases insulin-stimulated glucose...

  17. Single-blind, randomized, controlled trial of pelvic floor muscle training, electrical stimulation, vaginal cones, and no active treatment in the management of stress urinary incontinence

    Directory of Open Access Journals (Sweden)

    Rodrigo A. Castro

    2008-01-01

    Full Text Available PURPOSE: To compare the effectiveness of pelvic floor exercises, electrical stimulation, vaginal cones, and no active treatment in women with urodynamic stress urinary incontinence. PATIENTS AND METHODS: One hundred eighteen subjects were randomly selected to recieve pelvic floor exercises (n=31, ES (n=30, vaginal cones (n=27, or no treatment (untreated control (n=30. Women were evaluated before and after completion of six months of treatment by the pad test, quality of life questionnaire (I-QOL, urodynamic test, voiding diary, and subjective response. RESULTS: In the objective evaluation, we observed a statistically significant reduction in the pad test (p=0.003, in the number of stress urinary episodes (p<0.001, and a significant improvement in the quality of life (p<0.001 in subjects who used pelvic floor exercises, electrical stimulation, and vaginal cones compared to the control group. No significant difference was found between groups in the urodynamic parameters. In the subjective evaluation, 58%, 55%, and 54% of women who had used pelvic floor exercises, electrical stimulation, and vaginal cones, respectively, reported being satisfied after treatment. In the control group, only 21% patients were satisfied with the treatment. CONCLUSION: Based on this study, pelvic floor exercises, electrical stimulation, and vaginal cones are equally effective treatments and are far superior to no treatment in women with urodynamic stress urinary incontinence.

  18. Cross talk between MMP2-Spm-Cer-S1P and ERK1/2 in proliferation of pulmonary artery smooth muscle cells under angiotensin II stimulation.

    Science.gov (United States)

    Chowdhury, Animesh; Sarkar, Jaganmay; Pramanik, Pijush Kanti; Chakraborti, Tapati; Chakraborti, Sajal

    2016-08-01

    The aim of the present study is to establish the mechanism associated with the proliferation of PASMCs under ANG II stimulation. The results showed that treatment of PASMCs with ANG II induces an increase in cell proliferation and 100 nM was the optimum concentration for maximum increase in proliferation of the cells. Pretreatment of the cells with AT1, but not AT2, receptor antagonist inhibited ANG II induced cell proliferation. Pretreatment with pharmacological and genetic inhibitors of sphingomyelinase (SMase) and sphingosine kinase (SPHK) prevented ANG II-induced cell proliferation. ANG II has also been shown to induce SMase activity, SPHK phosphorylation and S1P production. In addition, ANG II caused an increase in proMMP-2 expression and activation, ERK1/2 phosphorylation and NADPH oxidase activation. Upon inhibition of MMP-2, SMase activity and S1P level were curbed leading to inhibition of cell proliferation. SPHK was phosphorylated by ERK1/2 during ET-1 stimulation of the cells. ANG II-induced ERK1/2 phosphorylation and proMMP-2 expression and activation in the cells were abrogated upon inhibition of NADPH oxidase activity. Overall, NADPH oxidase plays an important role in proMMP-2 expression and activation and that MMP-2 mediated SMC proliferation occurs through the involvement of Spm-Cer-S1P signaling axis under ANG II stimulation of PASMCs. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. 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.

  20. The effects of vibratory stimulation employed to forearm and arm flexor muscles on upper limb function in patients with chronic stroke.

    Science.gov (United States)

    Jung, Sang-Mi

    2017-09-01

    [Purpose] The purpose of this study was to investigate not only the effects of stimulatory vibration but also the retained effects 2 weeks after the last session of the intervention. [Subjects and Methods] Ten subjects with post-stroke hemiplegia were recruited in this study. The experimental group (EG) received vibratory stimulation for 30 minutes in each session, three times a week for 2 weeks. Grip strength (GS), box-and-block test (BBT), and Weinstein monofilament were used to assess hand strength, dexterity, and sensory in the affected hand, respectively. [Results] A significant difference was found between the pre- and post-follow-up BBT. Significant differences were found among the pre-posttest, post-follow-up test, and pre-follow-up test results for GS and BBT. [Conclusion] This study was conducted with 10 subjects, without a control group, to verify the pure effect of the intervention. As a result, significant positive effects were observed in the post-test and follow-up test of GS and BBT. Therefore, repeated vibratory stimulation influenced GS and BBT after the 2-week intervention and retained the effect for 2 more weeks.

  1. Low-load high volume resistance exercise stimulates muscle protein synthesis more than high-load low volume resistance exercise in young men.

    Directory of Open Access Journals (Sweden)

    Nicholas A Burd

    Full Text Available BACKGROUND: We aimed to determine the effect of resistance exercise intensity (%1 repetition maximum-1RM and volume on muscle protein synthesis, anabolic signaling, and myogenic gene expression. METHODOLOGY/PRINCIPAL FINDINGS: Fifteen men (21+/-1 years; BMI=24.1+/-0.8 kg/m2 performed 4 sets of unilateral leg extension exercise at different exercise loads and/or volumes: 90% of repetition maximum (1RM until volitional failure (90FAIL, 30% 1RM work-matched to 90%FAIL (30WM, or 30% 1RM performed until volitional failure (30FAIL. Infusion of [ring-13C6] phenylalanine with biopsies was used to measure rates of mixed (MIX, myofibrillar (MYO, and sarcoplasmic (SARC protein synthesis at rest, and 4 h and 24 h after exercise. Exercise at 30WM induced a significant increase above rest in MIX (121% and MYO (87% protein synthesis at 4 h post-exercise and but at 24 h in the MIX only. The increase in the rate of protein synthesis in MIX and MYO at 4 h post-exercise with 90FAIL and 30FAIL was greater than 30WM, with no difference between these conditions; however, MYO remained elevated (199% above rest at 24 h only in 30FAIL. There was a significant increase in AktSer473 at 24h in all conditions (P=0.023 and mTORSer2448 phosphorylation at 4 h post-exercise (P=0.025. Phosporylation of Erk1/2Tyr202/204, p70S6KThr389, and 4E-BP1Thr37/46 increased significantly (P<0.05 only in the 30FAIL condition at 4 h post-exercise, whereas, 4E-BP1Thr37/46 phosphorylation was greater 24 h after exercise than at rest in both 90FAIL (237% and 30FAIL (312% conditions. Pax7 mRNA expression increased at 24 h post-exercise (P=0.02 regardless of condition. The mRNA expression of MyoD and myogenin were consistently elevated in the 30FAIL condition. CONCLUSIONS/SIGNIFICANCE: These results suggest that low-load high volume resistance exercise is more effective in inducing acute muscle anabolism than high-load low volume or work matched resistance exercise modes.

  2. Limited effects of exogenous glucose during severe hypoxia and a lack of hypoxia-stimulated glucose uptake in isolated rainbow trout cardiac muscle

    Science.gov (United States)

    Becker, Tracy A.; DellaValle, Brian; Gesser, Hans; Rodnick, Kenneth J.

    2013-01-01

    SUMMARY We examined whether exogenous glucose affects contractile performance of electrically paced ventricle strips from rainbow trout under conditions known to alter cardiomyocyte performance, ion regulation and energy demands. Physiological levels of d-glucose did not influence twitch force development for aerobic preparations (1) paced at 0.5 or 1.1 Hz, (2) at 15 or 23°C, (3) receiving adrenergic stimulation or (4) during reoxygenation with or without adrenaline after severe hypoxia. Contractile responses to ryanodine, an inhibitor of Ca2+ release from the sarcoplasmic reticulum, were also not affected by exogenous glucose. However, glucose did attenuate the fall in twitch force during severe hypoxia. Glucose uptake was assayed in non-contracting ventricle strips using 2-[3H] deoxy-d-glucose (2-DG) under aerobic and hypoxic conditions, at different incubation temperatures and with different inhibitors. Based upon a lack of saturation of 2-DG uptake and incomplete inhibition of uptake by cytochalasin B and d-glucose, 2-DG uptake was mediated by a combination of facilitated transport and simple diffusion. Hypoxia stimulated lactate efflux sixfold to sevenfold with glucose present, but did not increase 2-DG uptake or reduce lactate efflux in the presence of cytochalasin B. Increasing temperature (14 to 24°C) also did not increase 2-DG uptake, but decreasing temperature (14 to 4°C) reduced 2-DG uptake by 45%. In conclusion, exogenous glucose improves mechanical performance under hypoxia but not under any of the aerobic conditions applied. The extracellular concentration of glucose and cold temperature appear to determine and limit cardiomyocyte glucose uptake, respectively, and together may help define a metabolic strategy that relies predominantly on intracellular energy stores. PMID:23685969

  3. Lipolysis in Skeletal Muscle

    DEFF Research Database (Denmark)

    Serup, Annette Karen Lundbeck

    chemical structure of DAG. We took advantage of the fact that insulin sensitivity is increased after exercise, and that mice knocked out (KO) of HSL accumulate DAG after exercise, and measured insulin stimulated glucose uptake after treadmill running in skeletal muscle from HSL KO mice and wildtype control...

  4. [Pelvic floor muscles training, electrical stimulation, bladder training and lifestyle interventions to manage lower urinary tract dysfunction in multiple sclerosis: a systematic review].

    Science.gov (United States)

    Gaspard, L; Tombal, B; Castille, Y; Opsomer, R-J; Detrembleur, C

    2014-03-01

    To assess the effectiveness of conservative therapeutic approaches in a multiple sclerosis population. Review was performed in PubMed, PEDro, Scopus and Cochrane Library using combinations of the following keywords: multiple sclerosis; bladder dysfunction; overactive bladder; detrusor hyperreflexia; urge incontinence; urgency; stress incontinence; pelvic floor muscle; biofeedback; PTNS; tibial nerve; bladder training; physical therapy; physiotherapy; conservative treatment and behavioral therapy. Six randomized articles including 289 patients were selected. Four papers exhibited strong scores for the methodological quality assessment. The parameters always significantly improved concerned: number of incontinence episodes (decreased from 64% to 86% after treatment versus before treatment), quality of life (P≤0.001), severity of irritative symptoms (decreased by more than 50% after treatment versus before treatment), and nocturia (P=0.035 to Ptreatment of urinary disorders in multiple sclerosis populations with mild disability. However, the analyses are based on six studies within only four showed good methodological quality. No strong conclusions regarding treatment approaches can be drawn from this review. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  5. Muscle Deoxygenation Causes Muscle Fatigue

    Science.gov (United States)

    Murthy, G.; Hargens, A. R.; Lehman, S.; Rempel, D.

    1999-01-01

    Muscle fatigue is a common musculoskeletal disorder in the work place, and may be a harbinger for more disabling cumulative trauma disorders. Although the cause of fatigue is multifactorial, reduced blood flow and muscle oxygenation may be the primary factor in causing muscle fatigue during low intensity muscle exertion. Muscle fatigue is defined as a reduction in muscle force production, and also occurs among astronauts who are subjected to postural constraints while performing lengthy, repetitive tasks. The objectives of this research are to: 1) develop an objective tool to study the role of decreased muscle oxygenation on muscle force production, and 2) to evaluate muscle fatigue during prolonged glovebox work.

  6. Muscle Cramps

    Science.gov (United States)

    ... Talk to your provider about the risks and benefits of medicines. How can I prevent muscle cramps? To prevent muscle cramps, you can Stretch your muscles, especially before exercising. If you often get leg cramps at night, ...

  7. Evaluation of the Combined Application of Neuromuscular Electrical Stimulation and Volitional Contractions on Thigh Muscle Strength, Knee Pain and Physical Performance in Women at Risk for Knee Osteoarthritis: A Randomized Controlled Trial.

    Science.gov (United States)

    Rabe, Kaitlin G; Matsuse, Hiroo; Jackson, Anthony; Segal, Neil A

    2018-05-28

    Knee osteoarthritis (OA) is a leading cause of disability that is associated with quadriceps weakness. However, strengthening in people with or with risk factors for knee OA can be poorly tolerated. To assess the efficacy of a twelve-week low-load exercise program, using a hybrid training system (HTS) that utilizes the combination of neuromuscular electrical stimulation and volitional contractions, for improving thigh muscle strength, knee pain and physical performance in women with or with risk factors for knee OA. Randomized, single-blind, controlled trial SETTING: Exercise training laboratory PARTICIPANTS: Forty-two women, age 44-85 years, with risk factors for knee OA INTERVENTIONS: Participants randomized to 12 weeks of biweekly low-load resistance training either with HTS or on an isokinetic dynamometer (control). Maximum isokinetic knee extensor torque. Secondary measures included: maximum isokinetic knee flexor torque, knee pain (KOOS), and timed 20-meter walk and chair-stand tests. HTS and control both resulted in muscle strengthening, reduced knee pain and improved physical performance. HTS group quadriceps and hamstring strength increased by 0.06±0.04 Nm/kg (p>.05) and 0.05±0.02 Nm/kg (p=.02), respectively. Control group quadriceps and hamstring strength increased by 0.03±0.04 Nm/kg (p>.05) and 0.06±0.02 Nm/kg (p=.009), respectively. Knee pain improved by 11.9±11.5 points (pmeter walk time decreased by 1.60±2.04 seconds (p=.005) and 0.95±1.2 seconds (p=.004), and chair stand time decreased by 4.8±10.0 seconds (p>.05) and 1.9±4.7 seconds (p>.05) in the HTS and control groups, respectively. These results did not differ statistically between HTS and control groups. These results suggest HTS is effective for improving pain and physical performance in women with risk factors for knee OA. However, HTS does not appear to be superior to low-load resistance training for improving muscle strength, pain or physical function. Copyright © 2018 American

  8. A muscle model for hybrid muscle activation

    Directory of Open Access Journals (Sweden)

    Klauer Christian

    2015-09-01

    Full Text Available To develop model-based control strategies for Functional Electrical Stimulation (FES in order to support weak voluntary muscle contractions, a hybrid model for describing joint motions induced by concurrent voluntary-and FES induced muscle activation is proposed. It is based on a Hammerstein model – as commonly used in feedback controlled FES – and exemplarily applied to describe the shoulder abduction joint angle. Main component of a Hammerstein muscle model is usually a static input nonlinearity depending on the stimulation intensity. To additionally incorporate voluntary contributions, we extended the static non-linearity by a second input describing the intensity of the voluntary contribution that is estimated by electromyography (EMG measurements – even during active FES. An Artificial Neural Network (ANN is used to describe the static input non-linearity. The output of the ANN drives a second-order linear dynamical system that describes the combined muscle activation and joint angle dynamics. The tunable parameters are adapted to the individual subject by a system identification approach using previously recorded I/O-data. The model has been validated in two healthy subjects yielding RMS values for the joint angle error of 3.56° and 3.44°, respectively.

  9. Suppression of the increasing level of acetylcholine-stimulated intracellular Ca2+ in guinea pig airway smooth muscle cells by mabuterol.

    Science.gov (United States)

    Song, Xirui; Zhao, Chao; Dai, Cailing; Ren, Yanxin; An, Nan; Wen, Huimin; Pan, L I; Cheng, Maosheng; Zhang, Yuyang

    2015-11-01

    The present study aimed to establish an effective method for the in vitro culture of guinea pig airway smooth muscle (ASM) cells, and also investigate the suppressive effect of mabuterol hydrochloride (Mab) on the increased level of intracellular Ca 2+ in ASM cells induced with acetylcholine (Ach). Two different methods, i.e. with or without collagenase to pretreat tracheal tissues, were applied to the manufacture of ASM cells. Cell viability was determined with the 3-(4,5-dimethylthinazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Immunocytochemistry and immunofluorescence were used for the identification of ASM cells. Different concentration levels (10 -3 , 10 -4 , 10 -5 , 10 -6 and 10 -7 mmol/l) of Mab were administered 5 min before Ach (10 -4 M) treatment, respectively. The Ca 2+ fluorescent probe, Fura-2/AM or Fluo-3/AM were applied to the inspection of Ca 2+ fluorescent intensity with Varioskan Flash, immunocytometry systems and an inverted system microscope, respectively. The results showed that the fresh method, in which isolated tracheal tissues were previously treated with collagenase for 20 min, was more advantageous for the preparation of guinea pig ASM cells compared to when the enzyme was not used. The time for the ASM cells to initially migrate out of the 'tissue blocks' and the culture having to be generated due to the thick cell density was significantly less. On identification with immunocytochemistry or immunofluorescent staining, >95% of the cells were ASM cells. Mab (10 -3 -10 -7 mmol/l) significantly suppressed the elevation of intracellular Ca 2+ induced by Ach in a concentration-dependent manner. The inhibitory rates of intracellular Ca 2+ by different concentrations of Mab, from low to high, were 14.93, 24.73, 40.06, 48.54 and 57.13%, respectively, when Varioskan Flash was used for determination. In conclusion, this novel method has a shorter harvesting period for ASM cells. Mab can suppress the increasing level of intracellular Ca 2

  10. Regeneração do músculo tibial anterior em diferentes períodos após lesão por estimulação elétrica neuromuscular Regeneration of the tibialis anterior muscle at different times following injury induced by neuromuscular electrical stimulation

    Directory of Open Access Journals (Sweden)

    AP Botelho

    2007-04-01

    Full Text Available CONTEXTUALIZAÇÃO: Lesões no musculoesquelético podem ser causadas pela própria contração muscular. OBJETIVO: Analisar em diferentes períodos a lesão do músculo tibial anterior (TA induzida pela eletroestimulação. MATERIAL E MÉTODO: ratos Wistar macho (298,2 ± 16,0g foram divididos nos grupos: eletroestimulado (EE e analisado após 3 e 5 dias (n= 20 e controle (C, 3 e 5 dias (n = 14. O TA, mantido em alongamento, foi lesado por eletroestimulação neuromuscular (90 min, 30Hz, 1m/s, Ton/Toff 4s e 4mA. Após 3 e 5 dias, os animais foram sacrificados e os músculos retirados, sendo os cortes histológicos (10 µm obtidos em criostato e corados com Azul de Toluidina. Os pesos corporal e muscular foram analisados estatisticamente pelo teste T-Student (p BACKGROUND: Skeletal muscle injuries may be caused by contraction of the muscle concerned. OBJECTIVE: To analyze the tibialis anterior muscle at different times following injury induced by electrical stimulation. METHOD: Male Wistar rats (298.2 ± 16.0g were divided into two electrically stimulated groups evaluated after three and five days (n= 20 and two control groups, also evaluated after three and five days (n= 14. While stretched, the tibialis anterior muscle was injured by neuromuscular electrical stimulation (90 minutes, 30 Hz, 1 m/s, Ton/Toff 4 s and 4 mA. Three and five days afterwards, the animals were sacrificed and the muscles were removed. Histological sections were cut (10 µm using a cryostat and were stained with toluidine blue. The body and muscle weights were statistically analyzed using Student's t test (p < 0.05. RESULTS: The final body weight was higher than the initial weight for the 3-day control group (288.5 ± 18.3g vs. 308.5 ± 24.3g and 5-day control group (288.4 ± 15.0g vs. 305.5 ± 20.7g and lower for the 3-day stimulated group (305.0 ± 13.0g vs. 285.6 ± 13.2g and 5-day stimulated group (306.1 ± 12.4g vs. 278.4 ± 20.9g. The relative muscle weight in the 5

  11. Corticospinal excitability changes following prolonged muscle tendon vibration

    NARCIS (Netherlands)

    Steyvers, M.; Levin, O.; Baelen, M.G.M. van; Swinnen, S.P.

    2003-01-01

    The present experiment addressed the time course of corticospinal excitability changes following interventional muscle tendon vibration. Using transcranial magnetic stimulation, motor evoked potentials of the flexor carpi radialis and extensor carpi radialis brevis muscle were recorded for a period

  12. Analysis of Postural Control Adaptation During Galvanic and Vibratory Stimulation

    National Research Council Canada - National Science Library

    Fransson, P

    2001-01-01

    The objective for this study was to investigate whether the postural control adaptation during galvanic stimulation of the vestibular nerve were similar to that found during vibration stimulation to the calf muscles...

  13. The Efficacy of Intraoperative Neurophysiological Monitoring Using Transcranial Electrically Stimulated Muscle-evoked Potentials (TcE-MsEPs) for Predicting Postoperative Segmental Upper Extremity Motor Paresis After Cervical Laminoplasty.

    Science.gov (United States)

    Fujiwara, Yasushi; Manabe, Hideki; Izumi, Bunichiro; Tanaka, Hiroyuki; Kawai, Kazumi; Tanaka, Nobuhiro

    2016-05-01

    Prospective study. To investigate the efficacy of transcranial electrically stimulated muscle-evoked potentials (TcE-MsEPs) for predicting postoperative segmental upper extremity palsy following cervical laminoplasty. Postoperative segmental upper extremity palsy, especially in the deltoid and biceps (so-called C5 palsy), is the most common complication following cervical laminoplasty. Some papers have reported that postoperative C5 palsy cannot be predicted by TcE-MsEPs, although others have reported that it can be predicted. This study included 160 consecutive cases that underwent open-door laminoplasty, and TcE-MsEP monitoring was performed in the biceps brachii, triceps brachii, abductor digiti minimi, tibialis anterior, and abductor hallucis. A >50% decrease in the wave amplitude was defined as an alarm point. According to the monitoring alarm, interventions were performed, which include steroid administration, foraminotomies, etc. Postoperative deltoid and biceps palsy occurred in 5 cases. Among the 155 cases without segmental upper extremity palsy, there were no monitoring alarms. Among the 5 deltoid and biceps palsy cases, 3 had significant wave amplitude decreases in the biceps during surgery, and palsy occurred when the patients awoke from anesthesia (acute type). In the other 2 cases in which the palsy occurred 2 days after the operation (delayed type), there were no significant wave decreases. In all of the cases, the palsy was completely resolved within 6 months. The majority of C5 palsies have been reported to occur several days after surgery, but some of them have been reported to occur immediately after surgery. Our results demonstrated that TcE-MsEPs can predict the acute type, whereas the delayed type cannot be predicted. A >50% wave amplitude decrease in the biceps is useful to predict acute-type segmental upper extremity palsy. Further examination about the interventions for monitoring alarm will be essential for preventing palsy.

  14. 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.

  15. Does Resistance Training Stimulate Cardiac Muscle Hypertrophy?

    Science.gov (United States)

    Bloomer, Richard J.

    2003-01-01

    Reviews the literature on the left ventricular structural adaptations induced by resistance/strength exercise, focusing on human work, particularly well-trained strength athletes engaged in regular, moderate- to high-intensity resistance training (RT). The article discusses both genders and examines the use of anabolic-androgenic steroids in…

  16. Electrical stimulation in exercise training

    Science.gov (United States)

    Kroll, Walter

    1994-01-01

    Electrical stimulation has a long history of use in medicine dating back to 46 A.D. when the Roman physician Largus found the electrical discharge of torpedo fishes useful in the treatment of pain produced by headache and gout. A rival Greek physician, Dioscorides, discounted the value of the torpedo fish for headache relief but did recommend its use in the treatment of hemorrhoids. In 1745, the Leyden jar and various sized electrostatic generators were used to treat angina pectoris, epilepsy, hemiplegia, kidney stones, and sciatica. Benjamin Franklin used an electrical device to treat successfully a young woman suffering from convulsive fits. In the late 1800's battery powered hydroelectric baths were used to treat chronic inflammation of the uterus while electrified athletic supporters were advertised for the treatment of male problems. Fortunately, such an amusing early history of the simple beginnings of electrical stimulation did not prevent eventual development of a variety of useful therapeutic and rehabilitative applications of electrical stimulation. Over the centuries electrical stimulation has survived as a modality in the treatment of various medical disorders with its primary application being in the rehabilitation area. Recently, a surge of new interest in electrical stimulation has been kindled by the work of a Russian sport scientist who reported remarkable muscle strength and endurance improvements in elite athletes. Yakov Kots reported his research on electric stimulation and strength improvements in 1977 at a Canadian-Soviet Exchange Symposium held at Concordia University in Montreal. Since then an explosion of new studies has been seen in both sport science and in medicine. Based upon the reported works of Kots and the present surge of new investigations, one could be misled as to the origin of electrical stimulation as a technique to increase muscle strength. As a matter of fact, electric stimulation has been used as a technique to improve

  17. 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.

  18. Muscle spindle autogenetic inhibition in the extraocular muscles of lamb.

    Science.gov (United States)

    Pettorossi, V E; Filippi, G M

    1981-09-01

    The role of extraocular muscle (EOM) proprioceptors on eye motility has been investigated in lambs on "encéphale isolé", by evaluating the tension of EOMs at various lengths and velocities of stretch before and after proprioceptive blocks. The EOM tension, in the absence of proprioceptive input, was higher than in normal conditions. Such an effect occurred at lengthening values greater than 3 mm of stretch from resting muscle length, corresponding to 18 degrees of eye deviation and was dependent on the velocity of the stretch, being more effective at high velocity. The muscle receptors responsible for this effect was determined by comparing the sensitivity to vibratory stimulation of spindles and tendon organs to the amount of inhibition provoked by the same stimulation on an EOM electromyographic activity. The tension inhibition appeared to be correlated to muscle spindle activation. Thus, the presence of muscle spindles can determine a reduction of the tension within the stretched muscles. This result suggests that the EOM length and velocity signals operate moment to moment reduction on the stiffness of the muscle which antagonizes eye displacement, thus facilitating the ocular movements.

  19. Differential effects of safflower oil versus fish oil feeding on insulin-stimulated glycogen synthesis, glycolysis, and pyruvate dehydrogenase flux in skeletal muscle: a 13C nuclear magnetic resonance study.

    Science.gov (United States)

    Jucker, B M; Cline, G W; Barucci, N; Shulman, G I

    1999-01-01

    To examine the effects of safflower oil versus fish oil feeding on in vivo intramuscular glucose metabolism and relative pyruvate dehydrogenase (PDH) versus tricarboxylic acid (TCA) cycle flux, rats were pair-fed on diets consisting of 1) 59% safflower oil, 2) 59% menhaden fish oil, or 3) 59% carbohydrate (control) in calories. Rates of glycolysis and glycogen synthesis were assessed by monitoring [1-(13)C]glucose label incorporation into [1-(13)C]glycogen, [3-(13)C]lactate, and [3-(13)C]alanine in the hindlimb of awake rats via 13C nuclear magnetic resonance (NMR) spectroscopy during a euglycemic (approximately 6 mmol/l) hyperinsulinemic (approximately 180 microU/ml) clamp. A steady-state isotopic analysis of lactate, alanine, and glutamate was used to determine the relative PDH versus TCA cycle flux present in muscle under these conditions. The safflower oil-fed rats were insulin resistant compared with control and fish oil-fed rats, as reflected by a markedly reduced glucose infusion rate (Ginf) during the clamp (21.4 +/- 2.3 vs. 31.6 +/- 2.8 and 31.7 +/- 1.9 mg x kg(-1) x min(-1) in safflower oil versus control and fish oil groups, respectively, P safflower oil group was associated with a lower rate of glycolysis (21.7 +/- 2.2 nmol x g(-1) x min(-1)) versus control (62.1 +/- 10.3 nmol x g(-1) x min(-1), P safflower oil, fish oil, and control, respectively) was detected. The intramuscular triglyceride (TG) content was increased in the safflower oil group (7.3 +/- 0.8 micromol/g) compared with the control group (5.2 +/- 0.8 micromol/g, P safflower oil (43 +/- 8%) versus the control (73 +/- 8%, P safflower oil feeding was a consequence of reduced glycolytic flux associated with an increase in relative free fatty acid/ketone oxidation versus TCA cycle flux, whereas fish oil feeding did not alter glucose metabolism and may in part be protective of insulin-stimulated glucose disposal by limiting intramuscular TG deposition.

  20. Inhibition of muscle spindle afferent activity during masseter muscle fatigue in the rat.

    Science.gov (United States)

    Brunetti, Orazio; Della Torre, Giovannella; Lucchi, Maria Luisa; Chiocchetti, Roberto; Bortolami, Ruggero; Pettorossi, Vito Enrico

    2003-09-01

    The influence of muscle fatigue on the jaw-closing muscle spindle activity has been investigated by analyzing: (1) the field potentials evoked in the trigeminal motor nucleus (Vmot) by trigeminal mesencephalic nucleus (Vmes) stimulation, (2) the orthodromic and antidromic responses evoked in the Vmes by stimulation of the peripheral and central axons of the muscle proprioceptive afferents, and (3) the extracellular unitary discharge of masseter muscle spindles recorded in the Vmes. The masseter muscle was fatigued by prolonged tetanic masseter nerve electrical stimulation. Pre- and postsynaptic components of the potentials evoked in the Vmot showed a significant reduction in amplitude following muscle fatigue. Orthodromic and antidromic potentials recorded in the Vmes also showed a similar amplitude decrease. Furthermore, muscle fatigue caused a decrease of the discharge frequency of masseter muscle spindle afferents in most of the examined units. The inhibition of the potential amplitude and discharge frequency was strictly correlated with the extent of muscle fatigue and was mediated by the group III and IV afferent muscle fibers activated by fatigue. In fact, the inhibitory effect was abolished by capsaicin injection in the masseter muscle that provokes selective degeneration of small afferent muscle fibers containing neurokinins. We concluded that fatigue signals originating from the muscle and traveling through capsaicin-sensitive fibers are able to diminish the proprioceptive input by a central presynaptic influence. In the second part of the study, we examined the central projection of the masseter small afferents sensitive to capsaicin at the electron-microscopic level. Fiber degeneration was induced by injecting capsaicin into the masseter muscle. Degenerating terminals were found on the soma and stem process in Vmes and on the dendritic tree of neurons in Vmot. This suggests that small muscle afferents may influence the muscle spindle activity through

  1. Immediate effect of laryngeal surface electrical stimulation on swallowing performance.

    Science.gov (United States)

    Takahashi, Keizo; Hori, Kazuhiro; Hayashi, Hirokazu; Fujiu-Kurachi, Masako; Ono, Takahiro; Tsujimura, Takanori; Magara, Jin; Inoue, Makoto

    2018-01-01

    Surface electrical stimulation of the laryngeal region is used to improve swallowing in dysphagic patients. However, little is known about how electrical stimulation affects tongue movements and related functions. We investigated the effect of electrical stimulation on tongue pressure and hyoid movement, as well as suprahyoid and infrahyoid muscle activity, in 18 healthy young participants. Electrical stimulation (0.2-ms duration, 80 Hz, 80% of each participant's maximal tolerance) of the laryngeal region was applied. Each subject swallowed 5 ml of barium sulfate liquid 36 times at 10-s intervals. During the middle 2 min, electrical stimulation was delivered. Tongue pressure, electromyographic activity of the suprahyoid and infrahyoid muscles, and videofluorographic images were simultaneously recorded. Tongue pressure during stimulation was significantly lower than before or after stimulation and was significantly greater after stimulation than at baseline. Suprahyoid activity after stimulation was larger than at baseline, while infrahyoid muscle activity did not change. During stimulation, the position of the hyoid at rest was descended, the highest hyoid position was significantly inferior, and the vertical movement was greater than before or after stimulation. After stimulation, the positions of the hyoid at rest and at the maximum elevation were more superior than before stimulation. The deviation of the highest positions of the hyoid before and after stimulation corresponded to the differences in tongue pressures at those times. These results suggest that surface electrical stimulation applied to the laryngeal region during swallowing may facilitate subsequent hyoid movement and tongue pressure generation after stimulation. NEW & NOTEWORTHY Surface electrical stimulation applied to the laryngeal region during swallowing may facilitate subsequent hyoid movement and tongue pressure generation after stimulation. Tongue muscles may contribute to overshot recovery

  2. Analysis of Facial Expression by Taste Stimulation

    Science.gov (United States)

    Tobitani, Kensuke; Kato, Kunihito; Yamamoto, Kazuhiko

    In this study, we focused on the basic taste stimulation for the analysis of real facial expressions. We considered that the expressions caused by taste stimulation were unaffected by individuality or emotion, that is, such expressions were involuntary. We analyzed the movement of facial muscles by taste stimulation and compared real expressions with artificial expressions. From the result, we identified an obvious difference between real and artificial expressions. Thus, our method would be a new approach for facial expression recognition.

  3. Efeitos da eletroestimulação do músculo vasto medial oblíquo em portadores de síndrome da dor patelofemoral: uma análise eletromiográfica Effects of electrical stimulation of vastus medialis obliquus muscle in patients with patellofemoral pain syndrome: an electromyographic analysis

    Directory of Open Access Journals (Sweden)

    Fabiana R. Garcia

    2010-12-01

    Full Text Available CONTEXTUALIZAÇÃO: O uso da eletromiografia de superfície (EMG-S tem sido considerado como instrumento de avaliação quantitativa na síndrome da dor patelofemoral (SDPF. Tratamentos conservadores objetivam melhorar o alinhamento patelar, e a estimulação elétrica do músculo vasto medial oblíquo (VMO tem sido considerada por ser seletiva e não causar irritação articular. OBJETIVO: Verificar o efeito de um programa de fortalecimento muscular com estimulação elétrica do VMO na SDPF por meio da capacidade de avaliação da EMG-S. MÉTODOS: Participaram deste estudo 10 mulheres jovens (idade: 23,1±4,9 anos; massa corporal: 66,8±14,0 kg; estatura: 1,63±6,9 cm; IMC: 25,1±5,6 kg/m² com SDPF unilateral, as quais realizaram o teste funcional de subir degrau para captação da atividade eletromiográfica dos músculos VMO e vasto lateral (VL, antes e após um programa de estimulação elétrica do VMO. A eletroestimulação foi realizada três vezes por semana, durante seis semanas. Foram consideradas, para análise entre VMO e VL, as variáveis razão do tempo do início até o pico de ativação, razão da integral do sinal (teste t para amostras dependentes e diferença de início de ativação (teste de Wilcoxon, com n��vel de significância de pBACKGROUND: The use of surface electromyography (SEMG has been considered a tool for quantitative assessment of patellofemoral pain syndrome (PFPS. Conservative treatments aim to improve patellar alignment, and electrical stimulation of the vastus medialis obliquus (VMO muscle has been considered effective because it is selective and does not cause joint irritation. OBJECTIVE: This study aims to investigate the efficiency of a muscle strengthening program with electrical stimulation of the VMO muscle in PFPS by SEMG. METHODS: A group of ten young women (age: 23.1±4.9 years; body mass: 66.8±14.0 kg; height: 1.63±6.9 cm; BMI: 25.1±5.6 kg/m² with unilateral PFPS participated in the

  4. Your Muscles

    Science.gov (United States)

    ... and you need to throw up. The muscles push the food back out of the stomach so it comes up ... body the power it needs to lift and push things. Muscles in your neck and the top part of your back aren't as large, but they are capable ...

  5. Muscle Plasticity and β2-Adrenergic Receptors: Adaptive Responses of β2-Adrenergic Receptor Expression to Muscle Hypertrophy and Atrophy

    OpenAIRE

    Shogo Sato; Ken Shirato; Kaoru Tachiyashiki; Kazuhiko Imaizumi

    2011-01-01

    We discuss the functional roles of β2-adrenergic receptors in skeletal muscle hypertrophy and atrophy as well as the adaptive responses of β2-adrenergic receptor expression to anabolic and catabolic conditions. β2-Adrenergic receptor stimulation using anabolic drugs increases muscle mass by promoting muscle protein synthesis and/or attenuating protein degradation. These effects are prevented ...

  6. growth stimulant

    African Journals Online (AJOL)

    Effects of timing and duration of supplementation of LIVFIT VET ® (growth stimulant) as substitute for fish meal on the growth performance, haematology and clinical enzymes concentration of growing pigs.

  7. PLASTICITY OF SKELETAL MUSCLE STUDIED BY STEREOLOGY

    Directory of Open Access Journals (Sweden)

    Ida Eržen

    2011-05-01

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

  8. Functional Electrical Stimulation in Children and Adolescents with Cerebral Palsy

    Science.gov (United States)

    van der Linden, Marietta

    2012-01-01

    In this article, the author talks about functional electrical stimulation in children and adolescents with cerebral palsy. Functional electrical stimulation (FES) is defined as the electrical stimulation of muscles that have impaired motor control, in order to produce a contraction to obtain functionally useful movement. It was first proposed in…

  9. Effects of electrical stimulation and stretching on the adaptation of denervated skeletal muscle: implications for physical therapy Efeitos da eletroestimulação e do alongamento muscular sobre a adaptação do músculo desnervado: implicações para a fisioterapia

    Directory of Open Access Journals (Sweden)

    Tania F. Salvini

    2012-06-01

    Full Text Available BACKGROUND: This review will describe the main cellular mechanisms involved in the reduction and increase of myoproteins synthesis commonly associated with muscle atrophy and hypertrophy, respectively. OBJECTIVE: We analyzed the effects of electrical stimulation (ES and stretching exercise on the molecular pathways involved in muscle atrophy and hypertrophy. We also described the main effects and limits of these resources in the skeletal muscle, particularly on the denervated muscle. DISCUSSION: Recently, our studies showed that the ES applied in a similar manner as performed in clinical practice is able to attenuate the increase of genes expression involved in muscle atrophy. However, ES was not effective to prevent the loss of muscle mass caused by denervation. Regarding to stretching exercises, their mechanisms of action on the denervated muscle are not fully understood and studies on this area are scarce. Studies from our laboratory have found that stretching exercise increased the extracellular matrix remodeling and decreased genes expression related to atrophy in denervated muscle. Nevertheless, it was not enough to prevent muscle atrophy after denervation. CONCLUSIONS: In spite of the use of stretching exercise and ES in clinical practice in order to minimize the atrophy of denervated muscle, there is still lack of scientific evidence to justify the effectiveness of these resources to prevent muscle atrophy in denervated muscle.CONTEXTUALIZAÇÃO: Esta revisão abordará os principais mecanismos celulares envolvidos na redução e aumento da síntese de mioproteínas comumente associadas às situações de atrofia e hipertrofia muscular, respectivamente. OBJETIVO: Analisaremos os efeitos da estimulação elétrica (EE e do exercício de alongamento sobre as vias moleculares envolvidas na atrofia e hipertrofia muscular. Serão descritos os principais efeitos e os limites desses recursos no músculo esquelético, particularmente sobre o m

  10. Functional Echomyography of the human denervated muscle: first results

    Directory of Open Access Journals (Sweden)

    Riccardo Zanato

    2011-03-01

    Full Text Available In this study we followed with ultrasound three patients with permanent denervation to evaluate changes in morphology, thickness, contraction and vascularisation of muscles undergoing the home-based electrical stimulation program of the Rise2-Italy project. During a period of 1 year for the first subject, 6 months for the second subject and 3 months for the third subject we studied with ultrasound the denervated muscle comparing it (if possible to the contralateral normal muscle. We evaluated: 1. Changes in morphology and sonographic structure of the pathologic muscle; 2. Muscular thickness in response to the electrical stimulation therapy; 3. Short-term modifications in muscle perfusion and arterial flow patterns after stimulation; 4. Contraction-relaxation kinetic induced by volitional activity or electrical stimulation. Morphology and ultrasonographic structure of the denervated muscles changed during the period of stimulation from a pattern typical of complete muscular atrophy to a pattern which might be considered “normal” when detected in an old patient. Thickness improved significantly more in the middle third than in the proximal and distal third of the denervated muscle, reaching in the last measurements of the first subject approximately the same thickness as the contralateral normal muscle. In all the measurements done within this study, arterial flow of the denervated muscle showed at rest a low-resistance pattern with Doppler Ultra Sound (US, and a pulsed pattern after electrical stimulation. The stimulation- induced pattern is similar to the trifasic high-resistance pattern of the normal muscle. Contraction- relaxation kinetic, measured by recording the muscular movements during electrical stimulation, showed an abnormal behaviour of the denervated muscle during the relaxation phase, which resulted to be significantly longer than in normal muscle (880 msec in the denervated muscle vs 240 msec in the contralateral normal one

  11. Muscle cramps

    Science.gov (United States)

    ... the lower leg/calf Back of the thigh (hamstrings) Front of the thigh (quadriceps) Cramps in the ... Names Cramps - muscle Images Chest stretch Groin stretch Hamstring stretch Hip stretch Thigh stretch Triceps stretch References ...

  12. Muscle atrophy

    Science.gov (United States)

    ... People who cannot actively move one or more joints can do exercises using braces or splints . When ... A.M. Editorial team. Muscle Disorders Read more Neuromuscular Disorders Read more NIH MedlinePlus Magazine Read more ...

  13. Stem Cell Antigen-1 in Skeletal Muscle Function

    OpenAIRE

    Bernstein, Harold S.; Samad, Tahmina; Cholsiripunlert, Sompob; Khalifian, Saami; Gong, Wenhui; Ritner, Carissa; Aurigui, Julian; Ling, Vivian; Wilschut, Karlijn J.; Bennett, Stephen; Hoffman, Julien; Oishi, Peter

    2013-01-01

    Stem cell antigen-1 (Sca-1) is a member of the Ly-6 multigene family encoding highly homologous, glycosyl-phosphatidylinositol-anchored membrane proteins. Sca-1 is expressed on muscle-derived stem cells and myogenic precursors recruited to sites of muscle injury. We previously reported that inhibition of Sca-1 expression stimulated myoblast proliferation in vitro and regulated the tempo of muscle repair in vivo. Despite its function in myoblast expansion during muscle repair, a role for Sca-1...

  14. Torze kolenních extenzorových svalů během izometrických cvičení a ruská elektrická stimulace po zranění kolenních vazů Knee extensor muscles' torque during isometric exercises and russian electrical stimulation following a knee ligament injury

    Directory of Open Access Journals (Sweden)

    Maciej Płaszewski

    2007-02-01

    Full Text Available Dobrovolné izometrické cvičení (VOL i neuromuskulární elektrická stimulace (NMES jsou metody rozvoje statické svalové síly. Používají se v programech pro rozvoj síly u zdravých svalů a také pro zotavování svalové funkce za určitých ortopedických podmínek. Obě metody se používají pro zpomalování svalové atrofie a ztráty síly v důsledku imobilizace kolena po zranění (Eriksson & Häggmark, 1979; Ingemann-Hansen & Halkjær-Kristensen, 1985; Johnson, 1988; Wigerstad-Lossing, Tromby, Jonsson, Morelli, Peterson, & Rentröm, 1988. NMES může vyvolat záškuby nebo tetanické svalové kontrakce, a to v závislosti na frekvenci proudových impulsů. Během tetanické stimulace jsou hlavními rysy nácvikových režimů: 1 cyklus zapnutí/vypnutí (pracovní cyklus, tvořený dobou kontrakce a dobou uvolnění; 2 počet kontrakcí; 3 intenzita kontrakcí (dána proudovou amplitudou nebo tolerancí subjektu. Voluntary isometric exercise (VOL and neuromuscular electrical stimulation (NMES are both methods of static muscle strength and girth training. They are applied in strength training programs to healthy muscle as well as for muscle function recovery under certain orthopaedic conditions. Both methods are used to retard muscle atrophy and strength loss resulting from post injury knee immobilization (Eriksson & Häggmark, 1979; Ingemann-Hansen & Halkjær-Kristensen, 1985; Johnson, 1988; Wigerstad-Lossing, Tromby, Jonsson, Morelli, Peterson, & Rentröm, 1988. NMES can elicit twitch or tetanic muscle contractions, determined by current pulse frequency. During tetanic stimulation, the main features of training regimes are: 1 on/off cycle (or duty cycle, made up of the time of contraction plus rest time; 2 the number of contractions; 3 the intensity of contractions (determined by the current amplitude and/or the subject’s tolerance.

  15. Functional electrical stimulation on paraplegic patients

    Directory of Open Access Journals (Sweden)

    Helmut Kern

    2014-07-01

    Full Text Available We report on clinical and physiological effects of 8 months Functional Electrical Stimulation (FES of quadriceps femoris muscle on 16 paraplegic patients. Each patient had muscle biopsies, CT-muscle diameter measurements, knee extension strength testing carried out before and after 8 months FES training. Skin perfusion was documented through infrared telethermography and xenon clearance, muscle perfusion was recorded through thallium scintigraphy. After 8 months FES training baseline skin perfusion showed 86 % increase, muscle perfusion was augmented by 87 %. Muscle fiber diameters showed an average increase of 59 % after 8 months FES training. Muscles in patients with spastic paresis as well as in patients with denervation showed an increase in aerob and anaerob muscle enzymes up to the normal range. Even without axonal neurotropic substances FES was able to demonstrate fiberhypertrophy, enzyme adaptation and intracellular structural benefits in denervated muscles. The increment in muscle area as visible on CT-scans of quadriceps femoris was 30 % in spastic paraplegia and 10 % in denervated patients respectively. FES induced changes were less in areas not directly underneath the surface electrodes. We strongly recommend the use of Kern`s current for FES in denervated muscles to induce tetanic muscle contractions as we formed a very critical opinion of conventional exponential current. In patients with conus-cauda-lesions FES must be integrated into modern rehabilitation to prevent extreme muscle degeneration and decubital ulcers. Using FES we are able to improve metabolism and induce positive trophic changes in our patients lower extremities. In spastic paraplegics the functions „rising and walking“ achieved through FES are much better training than FES ergometers. Larger muscle masses are activated and an increased heart rate is measured, therefore the impact on cardiovascular fitness and metabolism is much greater. This effectively

  16. Laser therapy of muscle injuries.

    Science.gov (United States)

    Dawood, Munqith S; Al-Salihi, Anam Rasheed; Qasim, Amenah Wala'a

    2013-05-01

    Low-level lasers are used in general therapy and healing process due to their good photo-bio-stimulation effects. In this paper, the effects of diode laser and Nd:YAG laser on the healing process of practically managed skeletal muscle trauma has been successfully studied. Standard impact trauma was induced by using a specially designed mechanical device. The impacted muscle was left for 3 days for complete development of blunt trauma. After that it was irradiated by five laser sessions for 5 days. Two types of lasers were used; 785-nm diode laser and 1.064-nm Nd:YAG laser, both in continuous and pulsed modes. A special electronic circuit was designed and implemented to modulate the diode laser for this purpose. Tissue samples of crushed skeletal muscle have been dissected from the injured irradiated muscle then bio-chemically analyzed for the regeneration of contractile and collagenous proteins using Lowry assay for protein determination and Reddy and Enwemeka assay for hydroxyproline determination. The results showed that both lasers stimulate the regeneration capability of traumatized skeletal muscle. The diode laser in CW and pulsed modes showed better results than the Nd:YAG in accelerating the preservation of the normal tissue content of collagenous and contractile proteins beside controlling the regeneration of non-functional fibrous tissue. This study proved that the healing achieved by the laser treatment was faster than the control group by 15-20 days.

  17. Insulin accelerates global and mitochondrial protein synthesis rates in neonatal muscle during sepsis

    Science.gov (United States)

    In neonatal pigs, sepsis decreases protein synthesis in skeletal muscle by decreasing translation initiation. However, insulin stimulates muscle protein synthesis despite persistent repression of translation initiation signaling. To determine whether the insulin-induced increase in global rates of m...

  18. Electrical stimulation of transplanted motoneurons improves motor unit formation

    Science.gov (United States)

    Liu, Yang; Grumbles, Robert M.

    2014-01-01

    Motoneurons die following spinal cord trauma and with neurological disease. Intact axons reinnervate nearby muscle fibers to compensate for the death of motoneurons, but when an entire motoneuron pool dies, there is complete denervation. To reduce denervation atrophy, we have reinnervated muscles in Fisher rats from local transplants of embryonic motoneurons in peripheral nerve. Since growth of axons from embryonic neurons is activity dependent, our aim was to test whether brief electrical stimulation of the neurons immediately after transplantation altered motor unit numbers and muscle properties 10 wk later. All surgical procedures and recordings were done in anesthetized animals. The muscle consequences of motoneuron death were mimicked by unilateral sciatic nerve section. One week later, 200,000 embryonic day 14 and 15 ventral spinal cord cells, purified for motoneurons, were injected into the tibial nerve 10–15 mm from the gastrocnemii muscles as the only neuron source for muscle reinnervation. The cells were stimulated immediately after transplantation for up to 1 h using protocols designed to examine differential effects due to pulse number, stimulation frequency, pattern, and duration. Electrical stimulation that included short rests and lasted for 1 h resulted in higher motor unit counts. Muscles with higher motor unit counts had more reinnervated fibers and were stronger. Denervated muscles had to be stimulated directly to evoke contractions. These results show that brief electrical stimulation of embryonic neurons, in vivo, has long-term effects on motor unit formation and muscle force. This muscle reinnervation provides the opportunity to use patterned electrical stimulation to produce functional movements. PMID:24848463

  19. Brain Stimulation Therapies

    Science.gov (United States)

    ... Magnetic Seizure Therapy Deep Brain Stimulation Additional Resources Brain Stimulation Therapies Overview Brain stimulation therapies can play ... for a shorter recovery time than ECT Deep Brain Stimulation Deep brain stimulation (DBS) was first developed ...

  20. Selective detrusor activation by electrical sacral nerve root stimulation in spinal cord injury

    NARCIS (Netherlands)

    Rijkhoff, N. J.; Wijkstra, H.; van Kerrebroeck, P. E.; Debruyne, F. M.

    1997-01-01

    Electrical sacral nerve root stimulation can be used in spinal cord injury patients to induce urinary bladder contraction. However, existing stimulation methods activate simultaneously both the detrusor muscle and the urethral sphincter. Urine evacuation is therefore only possible using poststimulus

  1. Activation of respiratory muscles during respiratory muscle training.

    Science.gov (United States)

    Walterspacher, Stephan; Pietsch, Fabian; Walker, David Johannes; Röcker, Kai; Kabitz, Hans-Joachim

    2018-01-01

    It is unknown which respiratory muscles are mainly activated by respiratory muscle training. This study evaluated Inspiratory Pressure Threshold Loading (IPTL), Inspiratory Flow Resistive Loading (IFRL) and Voluntary Isocapnic Hyperpnea (VIH) with regard to electromyographic (EMG) activation of the sternocleidomastoid muscle (SCM), parasternal muscles (PARA) and the diaphragm (DIA) in randomized order. Surface EMG were analyzed at the end of each training session and normalized using the peak EMG recorded during maximum inspiratory maneuvers (Sniff nasal pressure: SnPna, maximal inspiratory mouth occlusion pressure: PImax). 41 healthy participants were included. Maximal activation was achieved for SCM by SnPna; the PImax activated predominantly PARA and DIA. Activations of SCM and PARA were higher in IPTL and VIH than for IFRL (p<0.05). DIA was higher applying IPTL compared to IFRL or VIH (p<0.05). IPTL, IFRL and VIH differ in activation of inspiratory respiratory muscles. Whereas all methods mainly stimulate accessory respiratory muscles, diaphragm activation was predominant in IPTL. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Capsaicin-sensitive muscle afferents modulate the monosynaptic reflex in response to muscle ischemia and fatigue in the rat.

    Science.gov (United States)

    Della Torre, G; Brunetti, O; Pettorossi, V E

    2002-01-01

    The role of muscle ischemia and fatigue in modulating the monosynaptic reflex was investigated in decerebrate and spinalized rats. Field potentials and fast motoneuron single units in the lateral gastrocnemious (LG) motor pool were evoked by dorsal root stimulation. Muscle ischemia was induced by occluding the LG vascular supply and muscle fatigue by prolonged tetanic electrical stimulation of the LG motor nerve. Under muscle ischemia the monosynaptic reflex was facilitated since the size of the early and late waves of the field potential and the excitability of the motoneuron units increased. This effect was abolished after L3-L6 dorsal rhizotomy, but it was unaffected after L3-L6 ventral rhizotomy. By contrast, the monosynaptic reflex was inhibited by muscle fatiguing stimulation, and this effect did not fully depend on the integrity of the dorsal root. However, when ischemia was combined with repetitive tetanic muscle stimulation the inhibitory effect of fatigue was significantly enhanced. Both the ischemia and fatigue effects were abolished by capsaicin injected into the LG muscle at a dose that blocked a large number of group III and IV muscle afferents. We concluded that muscle ischemia and fatigue activate different groups of muscle afferents that are both sensitive to capsaicin, but enter the spinal cord through different roots. They are responsible for opposite effects, when given separately: facilitation during ischemia and inhibition during fatigue; however, in combination, ischemia enhances the responsiveness of the afferent fibres to fatigue.

  3. Growth factor involvement in tension-induced skeletal muscle growth

    Science.gov (United States)

    Vandenburgh, Herman H.

    1993-01-01

    Long-term manned space travel will require a better understanding of skeletal muscle atrophy which results from microgravity. Astronaut strength and dexterity must be maintained for normal mission operations and for emergency situations. Although exercise in space slows the rate of muscle loss, it does not prevent it. A biochemical understanding of how gravity/tension/exercise help to maintain muscle size by altering protein synthesis and/or degradation rate should ultimately allow pharmacological intervention to prevent muscle atrophy in microgravity. The overall objective is to examine some of the basic biochemical processes involved in tension-induced muscle growth. With an experimental in vitro system, the role of exogenous and endogenous muscle growth factors in mechanically stimulated muscle growth are examined. Differentiated avian skeletal myofibers can be 'exercised' in tissue culture using a newly developed dynamic mechanical cell stimulator device which simulates different muscle activity patterns. Patterns of mechanical activity which significantly affect muscle growth and metabolic characteristics were found. Both exogenous and endogenous growth factors are essential for tension-induced muscle growth. Exogenous growth factors found in serum, such as insulin, insulin-like growth factors, and steroids, are important regulators of muscle protein turnover rates and mechanically-induced muscle growth. Endogenous growth factors are synthesized and released into the culture medium when muscle cells are mechanically stimulated. At least one family of mechanically induced endogenous factors, the prostaglandins, help to regulate the rates of protein turnover in muscle cells. Endogenously synthesized IGF-1 is another. The interaction of muscle mechanical activity and these growth factors in the regulation of muscle protein turnover rates with our in vitro model system is studied.

  4. Transcranial magnetic stimulation and the human brain

    Science.gov (United States)

    Hallett, Mark

    2000-07-01

    Transcranial magnetic stimulation (TMS) is rapidly developing as a powerful, non-invasive tool for studying the human brain. A pulsed magnetic field creates current flow in the brain and can temporarily excite or inhibit specific areas. TMS of motor cortex can produce a muscle twitch or block movement; TMS of occipital cortex can produce visual phosphenes or scotomas. TMS can also alter the functioning of the brain beyond the time of stimulation, offering potential for therapy.

  5. Bio-inspired Hybrid Carbon Nanotube Muscles

    Science.gov (United States)

    Kim, Tae Hyeob; Kwon, Cheong Hoon; Lee, Changsun; An, Jieun; Phuong, Tam Thi Thanh; Park, Sun Hwa; Lima, Márcio D.; Baughman, Ray H.; Kang, Tong Mook; Kim, Seon Jeong

    2016-05-01

    There has been continuous progress in the development for biomedical engineering systems of hybrid muscle generated by combining skeletal muscle and artificial structure. The main factor affecting the actuation performance of hybrid muscle relies on the compatibility between living cells and their muscle scaffolds during cell culture. Here, we developed a hybrid muscle powered by C2C12 skeletal muscle cells based on the functionalized multi-walled carbon nanotubes (MWCNT) sheets coated with poly(3,4-ethylenedioxythiophene) (PEDOT) to achieve biomimetic actuation. This hydrophilic hybrid muscle is physically durable in solution and responds to electric field stimulation with flexible movement. Furthermore, the biomimetic actuation when controlled by electric field stimulation results in movement similar to that of the hornworm by patterned cell culture method. The contraction and relaxation behavior of the PEDOT/MWCNT-based hybrid muscle is similar to that of the single myotube movement, but has faster relaxation kinetics because of the shape-maintenance properties of the freestanding PEDOT/MWCNT sheets in solution. Our development provides the potential possibility for substantial innovation in the next generation of cell-based biohybrid microsystems.

  6. Teste de estimulação repetitiva no músculo ancôneo para diagnóstico da miastenia grave: mapeamento da sua área de placa motora Repetitive stimulation test on the anconeus muscle for the diagnosis of myasthenia gravis: the mapping of its motor end-plate area

    Directory of Open Access Journals (Sweden)

    Maria das Graças Wanderley S. Coriolano

    2007-06-01

    Full Text Available OBJETIVO: Mapear a área de placa motora do músculo ancôneo para definir a melhor localização dos eletrodos de registro em testes de estimulação repetitiva (TER no diagnóstico dos distúrbios da transmissão neuromuscular. MÉTODO: Registramos o potencial de ação composto do músculo ancôneo sobre a pele que o recobre, após estimulação do ramo que o inerva. Analisando as formas de onda registradas em cada ponto da pele foi possível definir a área de placa. RESULTADOS: A área de placa motora do ancôneo é uma linha paralela à borda da ulna. O melhor local de colocação do eletrodo "ativo" de registro situa-se cerca de 2 cm distal ao olécrano e 1 cm lateral à borda da ulna. CONCLUSÃO: A realização de TER no músculo ancôneo é simples e bem tolerada. Com a estimulação do ancôneo o antebraço praticamente não se move, sendo o procedimento livre de artefatos de movimento.PURPOSE: To map the motor end-plate area of the anconeus muscle and define the best place for positioning the recording electrodes in repetitive stimulation tests (RST for the diagnosis of neuromuscular transmission disorders. METHOD: The compound muscle action potential of the anconeus was recorded after stimulating the motor branch of the radial nerve that innervates it. By analyzing the waveforms registered at each point of the skin we were able to define the motor end-plate area. RESULTS: The motor end-plate area of the anconeus is a line parallel to the ulna border. The best place for placing the "active" recording electrode is about 2cm distal to the olecranon and 1 cm lateral to the border of the ulna. CONCLUSION: Performing RST in the anconeus muscle is simple and well tolerated. Stimulation of the anconeus almost doesn't move the forearm and the procedure is virtually free of movement artifacts.

  7. Muscle fibre capillarization is a critical factor in muscle fibre hypertrophy during resistance exercise training in older men.

    Science.gov (United States)

    Snijders, Tim; Nederveen, Joshua P; Joanisse, Sophie; Leenders, Marika; Verdijk, Lex B; van Loon, Luc J C; Parise, Gianni

    2017-04-01

    Adequate muscle fibre perfusion is critical for the maintenance of muscle mass; it is essential in the rapid delivery of oxygen, nutrients and growth factors to the muscle, stimulating muscle fibre growth. Muscle fibre capillarization is known to decrease substantially with advancing age. However, whether (relative) low muscle fibre capillarization negatively impacts the muscle hypertrophic response following resistance exercise training in older adults is unknown. Twenty-two healthy older men (71 ± 1 years) performed 24 weeks of progressive resistance type exercise training. To assess the change in muscle fibre characteristics, percutaneous biopsies from the vastus lateralis muscle were taken before and following 12 and 24 weeks of the intervention programme. A comparison was made between participants who had a relatively low type II muscle fibre capillary-to-fibre perimeter exchange index (CFPE; LOW group) and high type II muscle fibre CFPE (HIGH group) at baseline. Type I and type II muscle fibre size, satellite cell, capillary content and distance between satellite cells to the nearest capillary were determined by immunohistochemistry. Overall, type II muscle fibre size (from 5150 ± 234 to 6719 ± 446 µm 2 , P muscle fibre, P muscle fibre capillarization, whereas muscle fibre size (from 5170 ± 390 to 7133 ± 314 µm 2 , P muscle fibre, P muscle fibre capillarization were observed in response to 12 and 24 weeks of resistance exercise training in both the LOW and HIGH group. Type II muscle fibre capillarization at baseline may be a critical factor for allowing muscle fibre hypertrophy to occur during prolonged resistance exercise training in older men. © 2016 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of the Society on Sarcopenia, Cachexia and Wasting Disorders.

  8. PEDF-derived peptide promotes skeletal muscle regeneration through its mitogenic effect on muscle progenitor cells.

    Science.gov (United States)

    Ho, Tsung-Chuan; Chiang, Yi-Pin; Chuang, Chih-Kuang; Chen, Show-Li; Hsieh, Jui-Wen; Lan, Yu-Wen; Tsao, Yeou-Ping

    2015-08-01

    In response injury, intrinsic repair mechanisms are activated in skeletal muscle to replace the damaged muscle fibers with new muscle fibers. The regeneration process starts with the proliferation of satellite cells to give rise to myoblasts, which subsequently differentiate terminally into myofibers. Here, we investigated the promotion effect of pigment epithelial-derived factor (PEDF) on muscle regeneration. We report that PEDF and a synthetic PEDF-derived short peptide (PSP; residues Ser(93)-Leu(112)) induce satellite cell proliferation in vitro and promote muscle regeneration in vivo. Extensively, soleus muscle necrosis was induced in rats by bupivacaine, and an injectable alginate gel was used to release the PSP in the injured muscle. PSP delivery was found to stimulate satellite cell proliferation in damaged muscle and enhance the growth of regenerating myofibers, with complete regeneration of normal muscle mass by 2 wk. In cell culture, PEDF/PSP stimulated C2C12 myoblast proliferation, together with a rise in cyclin D1 expression. PEDF induced the phosphorylation of ERK1/2, Akt, and STAT3 in C2C12 myoblasts. Blocking the activity of ERK, Akt, or STAT3 with pharmacological inhibitors attenuated the effects of PEDF/PSP on the induction of C2C12 cell proliferation and cyclin D1 expression. Moreover, 5-bromo-2'-deoxyuridine pulse-labeling demonstrated that PEDF/PSP stimulated primary rat satellite cell proliferation in myofibers in vitro. In summary, we report for the first time that PSP is capable of promoting the regeneration of skeletal muscle. The signaling mechanism involves the ERK, AKT, and STAT3 pathways. These results show the potential utility of this PEDF peptide for muscle regeneration. Copyright © 2015 the American Physiological Society.

  9. Muscle glucose metabolism following exercise in the rat

    DEFF Research Database (Denmark)

    Richter, Erik; Garetto, L P; Goodman, M N

    1982-01-01

    Muscle glycogen stores are depleted during exercise and are rapidly repleted during the recovery period. To investigate the mechanism for this phenomenon, untrained male rats were run for 45 min on a motor-driven treadmill and the ability of their muscles to utilize glucose was then assessed during...... in glucose utilization enhanced by prior exercise appeared to be glucose transport across the cell membrane, as in neither control nor exercised rats did free glucose accumulate in the muscle cell. Following exercise, the ability of insulin to stimulate the release of lactate into the perfusate was unaltered......; however its ability to stimulate the incorporation of [(14)C]glucose into glycogen in certain muscles was enhanced. Thus at a concentration of 75 muU/ml insulin stimulated glycogen synthesis eightfold more in the fast-twitch red fibers of the red gastrocnemius than it did in the same muscle...

  10. Higher success rate with transcranial electrical stimulation of motor-evoked potentials using constant-voltage stimulation compared with constant-current stimulation in patients undergoing spinal surgery.

    Science.gov (United States)

    Shigematsu, Hideki; Kawaguchi, Masahiko; Hayashi, Hironobu; Takatani, Tsunenori; Iwata, Eiichiro; Tanaka, Masato; Okuda, Akinori; Morimoto, Yasuhiko; Masuda, Keisuke; Tanaka, Yuu; Tanaka, Yasuhito

    2017-10-01

    During spine surgery, the spinal cord is electrophysiologically monitored via transcranial electrical stimulation of motor-evoked potentials (TES-MEPs) to prevent injury. Transcranial electrical stimulation of motor-evoked potential involves the use of either constant-current or constant-voltage stimulation; however, there are few comparative data available regarding their ability to adequately elicit compound motor action potentials. We hypothesized that the success rates of TES-MEP recordings would be similar between constant-current and constant-voltage stimulations in patients undergoing spine surgery. The objective of this study was to compare the success rates of TES-MEP recordings between constant-current and constant-voltage stimulation. This is a prospective, within-subject study. Data from 100 patients undergoing spinal surgery at the cervical, thoracic, or lumbar level were analyzed. The success rates of the TES-MEP recordings from each muscle were examined. Transcranial electrical stimulation with constant-current and constant-voltage stimulations at the C3 and C4 electrode positions (international "10-20" system) was applied to each patient. Compound muscle action potentials were bilaterally recorded from the abductor pollicis brevis (APB), deltoid (Del), abductor hallucis (AH), tibialis anterior (TA), gastrocnemius (GC), and quadriceps (Quad) muscles. The success rates of the TES-MEP recordings from the right Del, right APB, bilateral Quad, right TA, right GC, and bilateral AH muscles were significantly higher using constant-voltage stimulation than those using constant-current stimulation. The overall success rates with constant-voltage and constant-current stimulations were 86.3% and 68.8%, respectively (risk ratio 1.25 [95% confidence interval: 1.20-1.31]). The success rates of TES-MEP recordings were higher using constant-voltage stimulation compared with constant-current stimulation in patients undergoing spinal surgery. Copyright © 2017

  11. Increased muscle glucose uptake during contractions

    DEFF Research Database (Denmark)

    Ploug, Thorkil; Galbo, Henrik; Richter, Erik

    1984-01-01

    We reinvestigated the prevailing concept that muscle contractions only elicit increased muscle glucose uptake in the presence of a so-called "permissive" concentration of insulin (Berger et al., Biochem. J. 146: 231-238, 1975; Vranic and Berger, Diabetes 28: 147-163, 1979). Hindquarters from rats...... in severe ketoacidosis were perfused with a perfusate containing insulin antiserum. After 60 min perfusion, electrical stimulation increased glucose uptake of the contracting muscles fivefold. Also, subsequent contractions increased glucose uptake in hindquarters from nondiabetic rats perfused for 1.5 h......-methylglucose uptake increased during contractions and glucose uptake was negative at rest and zero during contractions. An increase in muscle transport and uptake of glucose during contractions does not require the presence of insulin. Furthermore, glucose transport in contracting muscle may only increase if glycogen...

  12. Evaluation of muscle MRI in amyotrophic lateral sclerosis

    International Nuclear Information System (INIS)

    Baba, Yuri; Kuroiwa, Yoshiyuki

    2005-01-01

    Various objective measurements can be used to diagnose amyotrophic lateral sclerosis (ALS). T2-weighted brain MRI images revealed high signal areas at the posterior limb of the internal capsules in ALS patients. Recently, muscle MRI proved useful to evaluate abnormalities of the muscle in myositis patients. Therefore, in the present study, we examined muscle MRI of leg muscles in ALS patients, and correlated MRI with functional measurements, such as muscle strength, and compound muscle action potential amplitude of the tibialis anterior (TA) after stimulation of the peroneal nerve. The subjects consisted of 10 ALS patients (7 males and 3 females), ranging in age from 49 to 87. Neurologic symptoms at the onset of ALS consisted of bulbar dysfunction in one patient, upper extremity involvement in three patients, and lower extremity involvement in six patients. Muscle MRI of the legs was performed in 9 (ALS patients. A peripheral nerve conduction study was performed on the peroneal nerve, with the recording electrode over the TA. The T2-weighted muscle MRI images revealed high signal aeras in the muscle in six ALS patients, whose muscle weakness existed predominantly in the lower extremities. Extracellular fluid accumulation has been proposed to be responsible for the signal increase of denervated muscles on T2-weighted muscle MRI images. We assume that muscle MRI is useful to demonstrate the distribution of muscle involvement in ALS patients and to assess the disease's stage. (author)

  13. Botulinum toxin injection causes hyper-reflexia and increased muscle stiffness of the triceps surae muscle in the rat

    DEFF Research Database (Denmark)

    Pingel, Jessica; Wienecke, Jacob; Lorentzen, Jakob

    2016-01-01

    Botulinum toxin is used to diminish spasticity and reduce the risk of development of contractures. Here, we investigated changes in muscle stiffness caused by reflex activity or elastic muscle properties following botulinum toxin injection in the triceps surae muscle in rats. Forty-four rats...... received injection of botulinum toxin in the left triceps surae muscle. Control measurements were performed on the non-injected contralateral side in all rats. Acute experiments were performed 1, 2, 4 and 8 weeks following injection. The triceps surae muscle was dissected free, the Achilles tendon was cut...... and attached to a muscle puller. The resistance of the muscle to stretches of different amplitudes and velocities was systematically investigated. Reflex mediated torque was normalized to the maximal muscle force (Mmax) evoked by supramaximal stimulation of the tibial nerve. Botulinum toxin injection caused...

  14. Interaction of transcranial magnetic stimulation and electrical transmastoid stimulation in human subjects

    DEFF Research Database (Denmark)

    Taylor, Janet L; Petersen, Nicolas Caesar; Butler, Jane E

    2002-01-01

    Transcranial magnetic stimulation activates corticospinal neurones directly and transsynaptically and hence, activates motoneurones and results in a response in the muscle. Transmastoid stimulation results in a similar muscle response through activation of axons in the spinal cord. This study...... was designed to determine whether the two stimuli activate the same descending axons. Responses to transcranial magnetic stimuli paired with electrical transmastoid stimuli were examined in biceps brachii in human subjects. Twelve interstimulus intervals (ISIs) from -6 ms (magnet before transmastoid) to 5 ms......-wave, facilitation still occurred at ISIs of -6 and -5 ms and depression of the paired response at ISIs of 0, 1, 4 and 5 ms. The interaction of the response to transmastoid stimulation with the multiple descending volleys elicited by magnetic stimulation of the cortex is complex. However, depression of the response...

  15. Neurocontrol of the inverse dynamics in functional electrical stimulation

    NARCIS (Netherlands)

    Spaanenburg, L; Nijhuis, JAG; Ypma, A; Silva, FL; Principe, JC; Almeida, LB

    1997-01-01

    The rehabilitation of paraplegia can be pursued by functional electrical stimulation (FES) combined with biofeedback This requires control by surface electromyographical (EMG) signals to predict the muscle stimulation patterns while compensating the inherent phase lag. This can be realized by a

  16. Neuromuscular stimulation after stroke: from technology to clinical deployment

    NARCIS (Netherlands)

    IJzerman, Maarten Joost; Renzenbrink, Gerbert J.; Geurts, Alexander C.H.

    2009-01-01

    Since the early 1960s, electrical or neuromuscular electrical stimulation (NMES) has been used to support the rehabilitation of stroke patients. One of the earliest applications of NMES included the use of external muscle stimulation to correct drop-foot after stroke. During the last few decades

  17. Recruitment order of quadriceps motor units: femoral nerve vs. direct quadriceps stimulation.

    Science.gov (United States)

    Rodriguez-Falces, Javier; Place, Nicolas

    2013-12-01

    To investigate potential differences in the recruitment order of motor units (MUs) in the quadriceps femoris when electrical stimulation is applied over the quadriceps belly versus the femoral nerve. M-waves and mechanical twitches were evoked using femoral nerve stimulation and direct quadriceps stimulation of gradually increasing intensity from 20 young, healthy subjects. Recruitment order was investigated by analysing the time-to-peak twitch and the time interval from the stimulus artefact to the M-wave positive peak (M-wave latency) for the vastus medialis (VM) and vastus lateralis (VL) muscles. During femoral nerve stimulation, time-to-peak twitch and M-wave latency decreased consistently (P  0.05). For the VM muscle, M-wave latency decreased with increasing stimulation level for both femoral nerve and direct quadriceps stimulation, whereas, for the VL muscle, the variation of M-wave latency with stimulus intensity was different for the two stimulation geometries (P recruitment order during direct quadriceps stimulation was more complex, depending ultimately on the architecture of the peripheral nerve and its terminal branches below the stimulating electrodes for each muscle. For the VM, MUs were orderly recruited for both stimulation geometries, whereas, for the VL muscle, MUs were orderly recruited for femoral nerve stimulation, but followed no particular order for direct quadriceps stimulation.

  18. Efeito do treinamento funcional do assoalho pélvico associado ou não à eletroestimulação na incontinência urinária após prostatectomia radical Effect of functional training for the pelvic floor muscles with or without electrical stimulation in cases of urinary incontinence following radical prostatectomy

    Directory of Open Access Journals (Sweden)

    CT Kakihara

    2007-12-01

    radical prostatectomy is scarce, with descriptions of differing techniques for physical therapy treatment. OBJECTIVE: To evaluate the effect of physical therapy treatment for recovering urinary continence among patients who had undergone radical prostatectomy, by using functional training of the pelvic floor muscles with or without electrical stimulation. METHOD: Twenty patients with urinary incontinence following radical prostatectomy were selected. The patients were randomly allocated to a control or to an experimental group. The experimental group was composed of ten patients who received physical therapy treatment consisting of functional training of the pelvic floor muscles and electrical stimulation. The control group was composed of ten patients who received physical therapy treatment consisting only of functional training of the pelvic floor. All of the patients were reevaluated three, six and twelve months after beginning treatment, by using the pad test, visual analog scale (VAS for incontinence, VAS for the problem and counting the number of diapers (nappies used. RESULTS: There was a statistically significant decrease between the initial and 12th month evaluations of the pad test, VAS for incontinence, VAS for the problem and numbers of diapers of the control group and experimental group. However, no statistically significant difference was found when the same variable was compared between the two groups. CONCLUSION: There was no additional improvement from treatment with functional training of the pelvic floor muscles associated with electrical stimulation, in relation to treatment only using functional pelvic floor training. However, there was a significant improvement in urinary incontinence in both groups.

  19. Histological and radiographic evaluation of the muscle tissue of rats after implantation of bone morphogenic protein (rhBMP-2 in a scaffold of inorganic bone and after stimulation with low-power laser light

    Directory of Open Access Journals (Sweden)

    Bengtson Antonio

    2010-01-01

    Full Text Available Objective: The present study histologically and radiologically evaluates the muscle tissue of rats after implantation of bone morphogenic protein (rhBMP-2 in a natural inorganic bone mineral scaffold from a bull calf femur and irradiation with low-power light laser. Materials and Methods: The right and left hind limbs of 16 rats were shaved and an incision was made in the muscle on the face corresponding to the median portion of the tibia, into which rhBMP-2 in a scaffold of inorganic bone was implanted. Two groups of limbs were formed: control (G1 and laser irradiation (G2. G2 received diode laser light applied in the direction of the implant, at a dose of 8 J/cm2 for three minutes. On the 7th, 21st, 40th and 112th days after implantation, hind limbs of 4 animals were radiographed and their implants removed together with the surrounding tissue for study under the microscope. The histological results were graded as 0=absence, 1=slight presence, 2=representative and 3=very representative, with regard to the following events: formation of osteoid structure, acute inflammation, chronic inflammation, fibrin deposition, neovascularization, foreign-body granuloma and fibrosis. Results: There were no statistically significant differences in these events at each evaluation times, between the two groups (P > 0.05; Mann-Whitney test. Nevertheless, it could be concluded that the natural inorganic bone matrix with rhBMP-2, from the femur of a bull calf, is a biocompatible combination. Conclusions: Under these conditions, the inductive capacity of rhBMP-2 for cell differentiation was inhibited. There was a slight acceleration in tissue healing in the group that received irradiation with low-power laser light.

  20. Evaluation of the effectiveness of transcranial direct current stimulation (tDCS) and psychosensory stimulation through DOCS scale in a minimally conscious subject.

    Science.gov (United States)

    Dimitri, Danilo; De Filippis, Daniela; Galetto, Valentina; Zettin, Marina

    2017-04-01

    The aim of our study was to assess the effectiveness of transcranial direct current stimulation (tDCS) on alertness improvement in a patient in a minimally conscious state (MCS) by means of disorders of consciousness scale combined with psycho-sensory stimulation. The effects of tDCS on muscle hypertonia through the Ashworth scale were also examined. tDCS was performed through a two-channel intra-cephalic stimulator. After stimulation, the patient followed a psychosensory stimulation training. Results pointed out an increase in DOCunit score, as well as an increase in alertness maintenance and an improvement in muscle hypertonia, although a MCS state persisted.

  1. Electrically and hybrid-induced muscle activations: effects of muscle size and fiber type

    Directory of Open Access Journals (Sweden)

    Kelly Stratton

    2016-07-01

    Full Text Available The effect of three electrical stimulation (ES frequencies (10, 35, and 50 Hz on two muscle groups with different proportions of fast and slow twitch fibers (abductor pollicis brevis (APB and vastus lateralis (VL was explored. We evaluated the acute muscles’ responses individually and during hybrid activations (ES superimposed by voluntary activations. Surface electromyography (sEMG and force measurements were evaluated as outcomes. Ten healthy adults (mean age: 24.4 ± 2.5 years participated after signing an informed consent form approved by the university Institutional Review Board. Protocols were developed to: 1 compare EMG activities during each frequency for each muscle when generating 25% Maximum Voluntary Contraction (MVC force, and 2 compare EMG activities during each frequency when additional voluntary activation was superimposed over ES-induced 25% MVC to reach 50% and 75% MVC. Empirical mode decomposition (EMD was utilized to separate ES artifacts from voluntary muscle activation. For both muscles, higher stimulation frequency (35 and 50Hz induced higher electrical output detected at 25% of MVC, suggesting more recruitment with higher frequencies. Hybrid activation generated proportionally less electrical activity than ES alone. ES and voluntary activations appear to generate two different modes of muscle recruitment. ES may provoke muscle strength by activating more fatiguing fast acting fibers, but voluntary activation elicits more muscle coordination. Therefore, during the hybrid activation, less electrical activity may be detected due to recruitment of more fatigue-resistant deeper muscle fibers, not reachable by surface EMG.

  2. Vibration and muscle contraction affect somatosensory evoked potentials

    OpenAIRE

    Cohen, LG; Starr, A

    1985-01-01

    We recorded potentials evoked by specific somatosensory stimuli over peripheral nerve, spinal cord, and cerebral cortex. Vibration attenuated spinal and cerebral potentials evoked by mixed nerve and muscle spindle stimulation; in one subject that was tested, there was no effect on cutaneous input. Presynaptic inhibition of Ia input in the spinal cord and muscle spindle receptor occupancy are probably the responsible mechanisms. In contrast, muscle contraction attenuated cerebral potentials to...

  3. 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...

  4. Optical stimulation of peripheral nerves in vivo

    Science.gov (United States)

    Wells, Jonathon D.

    This dissertation documents the emergence and validation of a new clinical tool that bridges the fields of biomedical optics and neuroscience. The research herein describes an innovative method for direct neurostimulation with pulsed infrared laser light. Safety and effectiveness of this technique are first demonstrated through functional stimulation of the rat sciatic nerve in vivo. The Holmium:YAG laser (lambda = 2.12 mum) is shown to operate at an optimal wavelength for peripheral nerve stimulation with advantages over standard electrical neural stimulation; including contact-free stimulation, high spatial selectivity, and lack of a stimulation artifact. The underlying biophysical mechanism responsible for transient optical nerve stimulation appears to be a small, absorption driven thermal gradient sustained at the axonal layer of nerve. Results explicitly prove that low frequency optical stimulation can reliably stimulate without resulting in tissue thermal damage. Based on the positive results from animal studies, these optimal laser parameters were utilized to move this research into the clinic with a combined safety and efficacy study in human subjects undergoing selective dorsal rhizotomy. The clinical Holmium:YAG laser was used to effectively stimulate human dorsal spinal roots and elicit functional muscle responses recorded during surgery without evidence of nerve damage. Overall these results predict that this technology can be a valuable clinical tool in various neurosurgical applications.

  5. 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...

  6. Enhanced muscle glucose metabolism after exercise

    DEFF Research Database (Denmark)

    Richter, Erik; Garetto, L P; Goodman, M N

    1984-01-01

    Studies in the rat suggest that after voluntary exercise there are two phases of glycogen repletion in skeletal muscle (preceding study). In phase I glucose utilization and glycogen synthesis are enhanced both in the presence and absence of insulin, whereas in phase II only the increase in the pr......Studies in the rat suggest that after voluntary exercise there are two phases of glycogen repletion in skeletal muscle (preceding study). In phase I glucose utilization and glycogen synthesis are enhanced both in the presence and absence of insulin, whereas in phase II only the increase...... in the stimulated leg closely mimicked that observed previously after voluntary exercise on a treadmill. With no insulin added to the perfusate, glucose incorporation into glycogen was markedly enhanced in muscles that were glycogen depleted as were the uptake of 2-deoxyglucose and 3-O-methylglucose. Likewise......, the stimulation of these processes by insulin was enhanced and continued to be so 2 h later when the muscles of the stimulated leg had substantially repleted their glycogen stores. The results suggest that the increases in insulin-mediated glucose utilization and glycogen synthesis in muscle after exercise...

  7. The muscle protein synthetic response to food ingestion.

    Science.gov (United States)

    Gorissen, Stefan H M; Rémond, Didier; van Loon, Luc J C

    2015-11-01

    Preservation of skeletal muscle mass is of great importance for maintaining both metabolic health and functional capacity. Muscle mass maintenance is regulated by the balance between muscle protein breakdown and synthesis rates. Both muscle protein breakdown and synthesis rates have been shown to be highly responsive to physical activity and food intake. Food intake, and protein ingestion in particular, directly stimulates muscle protein synthesis rates. The postprandial muscle protein synthetic response to feeding is regulated on a number of levels, including dietary protein digestion and amino acid absorption, splanchnic amino acid retention, postprandial insulin release, skeletal muscle tissue perfusion, amino acid uptake by muscle, and intramyocellular signaling. The postprandial muscle protein synthetic response to feeding is blunted in many conditions characterized by skeletal muscle loss, such as aging and muscle disuse. Therefore, it is important to define food characteristics that modulate postprandial muscle protein synthesis. Previous work has shown that the muscle protein synthetic response to feeding can be modulated by changing the amount of protein ingested, the source of dietary protein, as well as the timing of protein consumption. Most of this work has studied the postprandial response to the ingestion of isolated protein sources. Only few studies have investigated the postprandial muscle protein synthetic response to the ingestion of protein dense foods, such as dairy and meat. The current review will focus on the capacity of proteins and protein dense food products to stimulate postprandial muscle protein synthesis and identifies food characteristics that may modulate the anabolic properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Functional Echomyography: thickness, ecogenicity, contraction and perfusion of the LMN denervated human muscle before and during h-bFES

    Directory of Open Access Journals (Sweden)

    Riccardo Zanato

    2010-03-01

    Full Text Available Permanent denervated muscles were evaluated by ultrasound to monitor changes in morphology, thickness, contraction-relaxation kinetics and perfusion due to the electrical stimulation program of the Rise2-Italy project. In a case of monolateral lesion, morphology and ultrasonographic structure of the denervated muscles changed during the period of stimulation from a pattern typical of complete denervation-induced muscle atrophy to a pattern which might be considered “normal” when detected in an old patient. Thickness improved significantly more in the middle third of the denervated muscle, reaching the same value as the contralateral innervated muscle. Contraction-relaxation kinetics, measured by recording the muscle movements during electrical stimulation, showed an abnormal behavior of the chronically denervated muscle during the relaxation phase, which resulted to be significantly longer than in normal muscle. The long-term denervated muscles analyzed with Echo Doppler showed at rest a low resistance arterial flow that became pulsed during and after electrical stimulation. As expected, the ultra sound measured electrical stimulation-induced hyperemia lasted longer than the stimulation period. The higher than normal energy of the delivered electrical stimuli of the Vienna home-based Functional Electrical Stimulation strategy (h-b FES demonstrate that the explored muscles were still almost completely denervated during the one-year of training. In conclusion, this pilot study confirms the usefulness of Functional Echomyography in the follow-up and the positive effects of h-b FES of denervated muscles.

  9. The anabolic potential of dietary protein intake on skeletal muscle is prolonged by prior light-load exercise

    DEFF Research Database (Denmark)

    Bechshøft, Rasmus; Dideriksen, Kasper; Reitelseder, Søren

    2013-01-01

    Hyperaminoacidemia stimulates myofibrillar fractional synthesis rate (myoFSR) transiently in resting skeletal muscle. We investigated whether light-load resistance exercise can extent this responsiveness....

  10. Extraocular muscle function testing

    Science.gov (United States)

    ... medlineplus.gov/ency/article/003397.htm Extraocular muscle function testing To use the sharing features on this page, please enable JavaScript. Extraocular muscle function testing examines the function of the eye muscles. ...

  11. Activation of the AMPK/Sirt1 pathway by a leucine-metformin combination increases insulin sensitivity in skeletal muscle, and stimulates glucose and lipid metabolism and increases life span in Caenorhabditis elegans.

    Science.gov (United States)

    Banerjee, Jheelam; Bruckbauer, Antje; Zemel, Michael B

    2016-11-01

    We have previously shown leucine (Leu) to activate Sirt1 by lowering its K M for NAD + , thereby amplifying the effects of other sirtuin activators and improving insulin sensitivity. Metformin (Met) converges on this pathway both indirectly (via AMPK) and by direct activation of Sirt1, and we recently found Leu to synergize with Met to improve insulin sensitivity and glycemic control while achieving ~80% dose-reduction in diet-induced obese mice. Accordingly, we sought here to define the mechanism of this interaction. Muscle cells C2C12 and liver cells HepG2 were used to test the effect of Met-Leu on Sirt1 activation. Caenorhabditis elegans was used for glucose utilization and life span studies. Leu (0.5mmol/L)+Met (50-100μmol/L) synergistically activated Sirt1 (pmetformin exerted no independent effect at any concentration (0.1-0.5mmol/L). Thus, Leu and Met synergize to enable Sirt1 activation at low NAD + concentrations (typical of energy replete states). Sirt1 and AMPK activations are required for Met-Leu's full action, which result in improvements in energy metabolism and insulin sensitivity. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Amino acids, independent of insulin, attenuate skeletal muscle autophagy in neonatal pigs during endotoxemia

    Science.gov (United States)

    Sepsis induces loss of skeletal muscle mass by activating the ubiquitin proteasome (UPS) and autophagy systems. Although muscle protein synthesis in healthy neonatal piglets is responsive to amino acids (AA) stimulation, it is not known if AA can prevent the activation of muscle protein degradation ...

  13. Neck muscle biomechanics and neural control.

    Science.gov (United States)

    Fice, Jason Bradley; Siegmund, Gunter P; Blouin, Jean-Sebastien

    2018-04-18

    The mechanics, morphometry, and geometry of our joints, segments and muscles are fundamental biomechanical properties intrinsic to human neural control. The goal of our study was to investigate if the biomechanical actions of individual neck muscles predicts their neural control. Specifically, we compared the moment direction & variability produced by electrical stimulation of a neck muscle (biomechanics) to their preferred activation direction & variability (neural control). Subjects sat upright with their head fixed to a 6-axis load cell and their torso restrained. Indwelling wire electrodes were placed into the sternocleidomastoid (SCM), splenius capitis (SPL), and semispinalis capitis (SSC) muscles. The electrically stimulated direction was defined as the moment direction produced when a current (2-19mA) was passed through each muscle's electrodes. Preferred activation direction was defined as the vector sum of the spatial tuning curve built from RMS EMG when subjects produced isometric moments at 7.5% and 15% of their maximum voluntary contraction (MVC) in 26 3D directions. The spatial tuning curves at 15% MVC were well-defined (unimodal, pbiomechanics but, as activation increases, biomechanical constraints in part dictate the activation of synergistic neck muscles.

  14. Effects of muscle activation on shear between human soleus and gastrocnemius muscles.

    Science.gov (United States)

    Finni, T; Cronin, N J; Mayfield, D; Lichtwark, G A; Cresswell, A G

    2017-01-01

    Lateral connections between muscles provide pathways for myofascial force transmission. To elucidate whether these pathways have functional roles in vivo, we examined whether activation could alter the shear between the soleus (SOL) and lateral gastrocnemius (LG) muscles. We hypothesized that selective activation of LG would decrease the stretch-induced shear between LG and SOL. Eleven volunteers underwent a series of knee joint manipulations where plantar flexion force, LG, and SOL muscle fascicle lengths and relative displacement of aponeuroses between the muscles were obtained. Data during a passive full range of motion were recorded, followed by 20° knee extension stretches in both passive conditions and with selective electrical stimulation of LG. During active stretch, plantar flexion force was 22% greater (P stronger (stiffer) connectivity between the two muscles, at least at flexed knee joint angles, which may serve to facilitate myofascial force transmission. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

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

    Science.gov (United States)

    Lee, Peter H U; Vandenburgh, Herman H

    2013-10-01

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

  16. The value of electrical stimulation as an exercise training modality

    Science.gov (United States)

    Currier, Dean P.; Ray, J. Michael; Nyland, John; Noteboom, Tim

    1994-01-01

    Voluntary exercise is the traditional way of improving performance of the human body in both the healthy and unhealthy states. Physiological responses to voluntary exercise are well documented. It benefits the functions of bone, joints, connective tissue, and muscle. In recent years, research has shown that neuromuscular electrical stimulation (NMES) simulates voluntary exercise in many ways. Generically, NMES can perform three major functions: suppression of pain, improve healing of soft tissues, and produce muscle contractions. Low frequency NMES may gate or disrupt the sensory input to the central nervous system which results in masking or control of pain. At the same time NMES may contribute to the activation of endorphins, serotonin, vasoactive intestinal polypeptides, and ACTH which control pain and may even cause improved athletic performances. Soft tissue conditions such as wounds and inflammations have responded very favorably to NMES. NMES of various amplitudes can induce muscle contractions ranging from weak to intense levels. NMES seems to have made its greatest gains in rehabilitation where directed muscle contractions may improve joint ranges of motion correct joint contractures that result from shortening muscles; control abnormal movements through facilitating recruitment or excitation into the alpha motoneuron in orthopedically, neurologically, or healthy subjects with intense sensory, kinesthetic, and proprioceptive information; provide a conservative approach to management of spasticity in neurological patients; by stimulation of the antagonist muscle to a spastic muscle stimulation of the agonist muscle, and sensory habituation; serve as an orthotic substitute to conventional bracing used with stroke patients in lieu of dorsiflexor muscles in preventing step page gait and for shoulder muscles to maintain glenohumeral alignment to prevent subluxation; and of course NMES is used in maintaining or improving the performance or torque producing

  17. Pathogenesis of Insulin Resistance in Skeletal Muscle

    Directory of Open Access Journals (Sweden)

    Muhammad A. Abdul-Ghani

    2010-01-01

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

  18. Physiological recruitment of motor units by high-frequency electrical stimulation of afferent pathways.

    Science.gov (United States)

    Dideriksen, Jakob L; Muceli, Silvia; Dosen, Strahinja; Laine, Christopher M; Farina, Dario

    2015-02-01

    Neuromuscular electrical stimulation (NMES) is commonly used in rehabilitation, but electrically evoked muscle activation is in several ways different from voluntary muscle contractions. These differences lead to challenges in the use of NMES for restoring muscle function. We investigated the use of low-current, high-frequency nerve stimulation to activate the muscle via the spinal motoneuron (MN) pool to achieve more natural activation patterns. Using a novel stimulation protocol, the H-reflex responses to individual stimuli in a train of stimulation pulses at 100 Hz were reliably estimated with surface EMG during low-level contractions. Furthermore, single motor unit recruitment by afferent stimulation was analyzed with intramuscular EMG. The results showed that substantially elevated H-reflex responses were obtained during 100-Hz stimulation with respect to a lower stimulation frequency. Furthermore, motor unit recruitment using 100-Hz stimulation was not fully synchronized, as it occurs in classic NMES, and the discharge rates differed among motor units because each unit was activated only after a specific number of stimuli. The most likely mechanism behind these observations is the temporal summation of subthreshold excitatory postsynaptic potentials from Ia fibers to the MNs. These findings and their interpretation were also verified by a realistic simulation model of afferent stimulation of a MN population. These results suggest that the proposed stimulation strategy may allow generation of considerable levels of muscle activation by motor unit recruitment that resembles the physiological conditions. Copyright © 2015 the American Physiological Society.

  19. Comparison of pre-workout nitric oxide stimulating dietary supplements on skeletal muscle oxygen saturation, blood nitrate/nitrite, lipid peroxidation, and upper body exercise performance in resistance trained men

    Directory of Open Access Journals (Sweden)

    Canale Robert E

    2010-05-01

    Full Text Available Abstract Background We compared Glycine Propionyl-L-Carnitine (GlycoCarn® and three different pre-workout nutritional supplements on measures of skeletal muscle oxygen saturation (StO2, blood nitrate/nitrite (NOx, lactate (HLa, malondialdehyde (MDA, and exercise performance in men. Methods Using a randomized, double-blind, cross-over design, 19 resistance trained men performed tests of muscular power (bench press throws and endurance (10 sets of bench press to muscular failure. A placebo, GlycoCarn®, or one of three dietary supplements (SUPP1, SUPP2, SUPP3 was consumed prior to exercise, with one week separating conditions. Blood was collected before receiving the condition and immediately after exercise. StO2 was measured during the endurance test using Near Infrared Spectroscopy. Heart rate (HR and rating of perceived exertion (RPE were determined at the end of each set. Results A condition effect was noted for StO2 at the start of exercise (p = 0.02, with GlycoCarn® higher than SUPP2. A condition effect was also noted for StO2 at the end of exercise (p = 0.003, with SUPP1 lower than all other conditions. No statistically significant interaction, condition, or time effects were noted for NOx or MDA (p > 0.05; however, MDA decreased 13.7% with GlycoCarn® and increased in all other conditions. Only a time effect was noted for HLa (p 0.05; however, GlycoCarn® resulted in a statistically insignificant greater total volume load compared to the placebo (3.3%, SUPP1 (4.2%, SUPP2 (2.5%, and SUPP3 (4.6%. Conclusion None of the products tested resulted in favorable changes in our chosen outcome measures, with the exception of GlycoCarn® in terms of higher StO2 at the start of exercise. GlycoCarn® resulted in a 13.7% decrease in MDA from pre- to post-exercise and yielded a non-significant but greater total volume load compared to all other conditions. These data indicate that 1 a single ingredient (GlycoCarn® can provide similar practical benefit

  20. Separation and estimation of muscle spindle and tension receptor populations by vibration of the biceps muscle in the frog.

    Science.gov (United States)

    Giszter, S F; Kargo, W J

    2002-10-01

    Frog spinal cord reflex behaviors have been used to test the idea of spinal primitives. We have suggested a significant role for proprioception in regulation of primitives. However the in vivo behavior of spindle and golgi tendon receptors in frogs in response to vibration are not well described and the proportions of these proprioceptors are not established. In this study, we examine the selectivity of muscle vibration in the spinal frog. The aim of the study was (1) to examine how hindlimb muscle spindles and GTO receptors are activated by muscle vibration and (2) to estimate the relative numbers of GTO receptors and spindle afferents in a selected muscle, for comparison with the mammal. Single muscle afferents from the biceps muscle were identified in the dorsal roots. These were tested in response to biceps vibration, intramuscular stimulation and biceps nerve stimulation. Biceps units were categorized into two types: First, spindle afferents which had a high conduction velocity (approximately 20-30 m/s), responded reliably (were entrained 1:1) to muscle vibration, and exhibited distinct pauses to shortening muscle contractions. Second, golgi tendon organ afferents, which had a lower conduction velocity (approximately 10-20 m/s), responded less reliably to muscle vibration at physiologic muscle lengths, but responded more reliably at extended lengths or with background muscle contraction, and exhibited distinct bursts to shortening muscle contractions. Vibration responses of these units were tested with and without muscle curarization. Ensemble (suction electrode) recordings from the dorsal roots were used to provide rough estimates of the proportions of the two muscle afferent types.