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Journal articles on the topic 'Muscle contraction'

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1

Conley, Kevin E., and Stan L. Lindstedt. "Energy-saving mechanisms in muscle: the minimization strategy." Journal of Experimental Biology 205, no. 15 (2002): 2175–81. http://dx.doi.org/10.1242/jeb.205.15.2175.

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SUMMARYMany mechanisms reduce the cost of muscle activity. Here, we describe a set of specializations that reduce the cost of contraction in the high-frequency twitches that are used by a wide variety of animals for either sound production or flight. Minimizing the cost of these contractions means that cellular ATP production can meet ATP demand and sustain the high contractile rate. Two classes of specialization are found that minimize the contractile cost. The first class reduces the muscle work required per contraction. Light appendages such as rattles, insect limbs and membranous wings tha
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2

Hogan, Michael C., Erica Ingham, and S. Sadi Kurdak. "Contraction duration affects metabolic energy cost and fatigue in skeletal muscle." American Journal of Physiology-Endocrinology and Metabolism 274, no. 3 (1998): E397—E402. http://dx.doi.org/10.1152/ajpendo.1998.274.3.e397.

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It has been suggested that during a skeletal muscle contraction the metabolic energy cost at the onset may be greater than the energy cost related to holding steady-state force. The purpose of the present study was to investigate the effect of contraction duration on the metabolic energy cost and fatigue process in fully perfused contracting muscle in situ. Canine gastrocnemius muscle ( n = 6) was isolated, and two contractile periods (3 min of isometric, tetanic contractions with 45-min rest between) were conducted by each muscle in a balanced order design. The two contractile periods had sti
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3

Thomas, G. D., J. Hansen, and R. G. Victor. "Inhibition of alpha 2-adrenergic vasoconstriction during contraction of glycolytic, not oxidative, rat hindlimb muscle." American Journal of Physiology-Heart and Circulatory Physiology 266, no. 3 (1994): H920—H929. http://dx.doi.org/10.1152/ajpheart.1994.266.3.h920.

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Previous studies have produced conflicting evidence as to whether sympathetic vasoconstriction is impaired in active skeletal muscle. Because alpha 2-, not alpha 1-, adrenergic vasoconstriction is attenuated by mild acidosis, we hypothesized that alpha 2-mediated sympathetic vasoconstriction would be attenuated in contracting glycolytic muscle, which produces more acidosis than oxidative muscle. We compared effects of lumbar sympathetic nerve stimulation and alpha-adrenergic agonists on arterial pressure, femoral blood flow, and force output during contractions of oxidative or glycolytic muscl
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4

Todd, Gabrielle, Janet L. Taylor, Jane E. Butler, Peter G. Martin, Robert B. Gorman, and Simon C. Gandevia. "Use of motor cortex stimulation to measure simultaneously the changes in dynamic muscle properties and voluntary activation in human muscles." Journal of Applied Physiology 102, no. 5 (2007): 1756–66. http://dx.doi.org/10.1152/japplphysiol.00962.2006.

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Force responses to transcranial magnetic stimulation of motor cortex (TMS) during exercise provide information about voluntary activation and contractile properties of the muscle. Here, TMS-generated twitches and muscle relaxation during the TMS-evoked silent period were measured in fresh, heated, and fatigued muscle. Subjects performed isometric contractions of elbow flexors in two studies. Torque and EMG were recorded from elbow flexor and extensor muscles. One study ( n = 6) measured muscle contraction times and relaxation rates during brief maximal and submaximal contractions in fresh and
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5

Günther, Michael, Oliver Röhrle, Daniel F. B. Haeufle, and Syn Schmitt. "Spreading out Muscle Mass within a Hill-Type Model: A Computer Simulation Study." Computational and Mathematical Methods in Medicine 2012 (2012): 1–13. http://dx.doi.org/10.1155/2012/848630.

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It is state of the art that muscle contraction dynamics is adequately described by a hyperbolic relation between muscle force and contraction velocity (Hill relation), thereby neglecting muscle internal mass inertia (first-order dynamics). Accordingly, the vast majority of modelling approaches also neglect muscle internal inertia. Assuming that such first-order contraction dynamics yet interacts with muscle internal mass distribution, this study investigates two questions: (i) what is the time scale on which the muscle responds to a force step? (ii) How does this response scale with muscle des
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6

Kato, Tatsuya, Atsushi Sasaki, Hikaru Yokoyama, Matija Milosevic, and Kimitaka Nakazawa. "Effects of neuromuscular electrical stimulation and voluntary commands on the spinal reflex excitability of remote limb muscles." Experimental Brain Research 237, no. 12 (2019): 3195–205. http://dx.doi.org/10.1007/s00221-019-05660-6.

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Abstract It is well known that contracting the upper limbs can affect spinal reflexes of the lower limb muscle, via intraneuronal networks within the central nervous system. However, it remains unknown whether neuromuscular electrical stimulation (NMES), which can generate muscle contractions without central commands from the cortex, can also play a role in such inter-limb facilitation. Therefore, the objective of this study was to compare the effects of unilateral upper limb contractions using NMES and voluntary unilateral upper limb contractions on the inter-limb spinal reflex facilitation i
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7

Stebbins, C. L., O. A. Carretero, T. Mindroiu, and J. C. Longhurst. "Bradykinin release from contracting skeletal muscle of the cat." Journal of Applied Physiology 69, no. 4 (1990): 1225–30. http://dx.doi.org/10.1152/jappl.1990.69.4.1225.

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Results of previous studies from our laboratory suggest that bradykinin has a role in the exercise pressor reflex elicited by static muscle contraction. The purpose of this study was to quantify the release of bradykinin from contracting skeletal muscle. In 18 cats, blood samples were withdrawn directly from the venous effluent of the triceps surae muscles immediately before and after 30 s of static contraction producing peak muscle tensions of 33, 50, and 100% of maximum electrically stimulated contraction. Contractions producing muscle tensions of 50 and 100% of maximum increased muscle veno
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8

Hogan, Michael C., Bruno Grassi, Michele Samaja, Creed M. Stary, and L. B. Gladden. "Effect of contraction frequency on the contractile and noncontractile phases of muscle venous blood flow." Journal of Applied Physiology 95, no. 3 (2003): 1139–44. http://dx.doi.org/10.1152/japplphysiol.00226.2003.

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The purpose of this study was to test the hypothesis that increasing muscle contraction frequency, which alters the duty cycle and metabolic rate, would increase the contribution of the contractile phase to mean venous blood flow in isolated skeletal muscle during rhythmic contractions. Canine gastrocnemius muscle ( n = 5) was isolated, and 3-min stimulation periods of isometric, tetanic contractions were elicited sequentially at rates of 0.25, 0.33, and 0.5 contractions/s. The O2 uptake, tension-time integral, and mean venous blood flow increased significantly ( P < 0.05) with each contrac
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9

Hespel, P., and E. A. Richter. "Mechanism linking glycogen concentration and glycogenolytic rate in perfused contracting rat skeletal muscle." Biochemical Journal 284, no. 3 (1992): 777–80. http://dx.doi.org/10.1042/bj2840777.

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The influence of differences in glycogen concentration on glycogen breakdown and on phosphorylase activity was investigated in perfused contracting rat skeletal muscle. The rats were preconditioned by a combination of swimming exercise and diet (carbohydrate-free or carbohydrate-rich) in order to obtain four sub-groups of rats with varying resting muscle glycogen concentrations (range 10-60 mumol/g wet wt.). Pre-contraction muscle glycogen concentration was closely positively correlated with glycogen breakdown over 15 min of intermittent short tetanic contractions (r = 0.75; P less than 0.001;
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10

Herdmann, J., P. Enck, P. Zacchi-Deutschbein, and U. Ostermann. "Speed and pressure characteristics of external anal sphincter contractions." American Journal of Physiology-Gastrointestinal and Liver Physiology 269, no. 2 (1995): G225—G231. http://dx.doi.org/10.1152/ajpgi.1995.269.2.g225.

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The principle of isochronism reflects constant contraction time for varying strengths of muscle contraction. This principle was studied for the innervation of the pelvic floor in humans using motor-evoked potentials (MEPs) and evoked pressure curves (EPCs) from the external anal sphincter muscle (EAS). MEPs and EPCs were simultaneously recorded after transcranial magnetic stimulation of the motor cortex. Voluntary contractions were also studied. Contraction times of the EAS were significantly longer in voluntary contractions (mean, 237 ms) than in EPCs (mean, 90 ms). Depending on either mode o
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11

Sosnowska, Anna J., Aleksandra Vuckovic, and Henrik Gollee. "Automated semi-real-time detection of muscle activity with ultrasound imaging." Medical & Biological Engineering & Computing 59, no. 9 (2021): 1961–71. http://dx.doi.org/10.1007/s11517-021-02407-w.

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AbstractUltrasound imaging (USI) biofeedback is a useful therapeutic tool; however, it relies on qualitative assessment by a trained therapist, while existing automatic analysis techniques are computationally demanding. This study aims to present a computationally inexpensive algorithm based on the difference in pixel intensity between USI frames. During an offline experiment, where data was analyzed after the study, participants performed isometric contractions of the gastrocnemius medialis (GM) muscle, as executed (30% of maximum contraction) or attempted (low force contraction up to a point
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12

Goodyear, L. J., P. A. King, M. F. Hirshman, C. M. Thompson, E. D. Horton, and E. S. Horton. "Contractile activity increases plasma membrane glucose transporters in absence of insulin." American Journal of Physiology-Endocrinology and Metabolism 258, no. 4 (1990): E667—E672. http://dx.doi.org/10.1152/ajpendo.1990.258.4.e667.

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To study the interactions between insulin and contraction on the skeletal muscle glucose transport system, the hindquarters of male rats were perfused in the absence of insulin, in the presence of insulin (30 mU/ml), during contractions induced by sciatic nerve stimulation, or during contractions plus insulin. Compared with control preparations, rates of glucose uptake in the perfused hindquarter were increased by 2.5- and 2.6-fold in the insulin and insulin plus contraction groups, respectively, but not significantly increased in the contraction only preparations. After perfusion, soleus and
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13

Lockhart, Nicole C., and Susan V. Brooks. "Neutrophil accumulation following passive stretches contributes to adaptations that reduce contraction-induced skeletal muscle injury in mice." Journal of Applied Physiology 104, no. 4 (2008): 1109–15. http://dx.doi.org/10.1152/japplphysiol.00850.2007.

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Skeletal muscles can be injured by their own contractions, especially when the muscle is stretched during a lengthening contraction. Exposing a muscle to a conditioning protocol of stretches without activation (passive stretches) before lengthening contractions reduces contraction-induced injury. Although passive stretching does not damage muscle fibers, neutrophils are elevated in the muscle after passive stretches. Our purpose was to investigate the relationship between neutrophil accumulation following passive stretches and the protection from subsequent contraction-induced injury provided
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14

Mehta, D., M. F. Wu, and S. J. Gunst. "Role of contractile protein activation in the length-dependent modulation of tracheal smooth muscle force." American Journal of Physiology-Cell Physiology 270, no. 1 (1996): C243—C252. http://dx.doi.org/10.1152/ajpcell.1996.270.1.c243.

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The active isometric force developed by a muscle decreases at muscle lengths below an optimal length (Lo). However, when the length of an actively contracting muscle is abruptly decreased, a lower level of isometric force is reached during force redevelopment than when the contraction is initiated at the shorter length. This has been attributed to a deactivation of contractile proteins caused by shortening. In this study, intracellular Ca2+ and myosin light chain (MLC) phosphorylation were measured to assess the mechanisms for the modulation of isometric force caused by changing smooth muscle
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15

Eng, Carolyn M., and Thomas J. Roberts. "Aponeurosis influences the relationship between muscle gearing and force." Journal of Applied Physiology 125, no. 2 (2018): 513–19. http://dx.doi.org/10.1152/japplphysiol.00151.2018.

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Aponeuroses are connective tissues found on the surface of pennate muscles and are in close association with muscle fascicles. In addition to transmitting muscle forces to the external tendon, aponeurosis has been hypothesized to influence the direction of muscle shape change during a contraction. Muscle shape changes affect muscle contractile force and velocity because they influence the gear ratio with which muscle fascicles transmit force and velocity to the tendon. If aponeurosis modulates muscle shape changes, altering the aponeurosis’ radial integrity with incisions should alter gearing.
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16

Andersen, Ole Emil, Ole Bækgaard Nielsen, and Kristian Overgaard. "Early effects of eccentric contractions on muscle glucose uptake." Journal of Applied Physiology 126, no. 2 (2019): 376–85. http://dx.doi.org/10.1152/japplphysiol.00388.2018.

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Muscle-damaging eccentric exercise impairs muscle glucose uptake several hours to days after exercise. Little, however, is known about the acute effects of eccentric exercise on contraction- and insulin-induced glucose uptake. This study compares glucose uptake rates in the first hours following eccentric, concentric, and isometric contractions with and without insulin present. Isolated rat extensor digitorum longus muscles were exposed to either an eccentric, concentric, or isometric contraction protocol, and muscle contractions were induced by electric stimulation that was identical between
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17

AlMohimeed, Ibrahim, and Yuu Ono. "Ultrasound Measurement of Skeletal Muscle Contractile Parameters Using Flexible and Wearable Single-Element Ultrasonic Sensor." Sensors 20, no. 13 (2020): 3616. http://dx.doi.org/10.3390/s20133616.

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Skeletal muscle is considered as a near-constant volume system, and the contractions of the muscle are related to the changes in tissue thickness. Assessment of the skeletal muscle contractile parameters such as maximum contraction thickness ( T h ), contraction time ( T c ), contraction velocity ( V c ), sustain time ( T s ), and half-relaxation ( T r ) provides valuable information for various medical applications. This paper presents a single-element wearable ultrasonic sensor (WUS) and a method to measure the skeletal muscle contractile parameters in A-mode ultrasonic data acquisition. The
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18

Zuo, Li, Leonardo Nogueira, and Michael C. Hogan. "Reactive oxygen species formation during tetanic contractions in single isolated Xenopus myofibers." Journal of Applied Physiology 111, no. 3 (2011): 898–904. http://dx.doi.org/10.1152/japplphysiol.00398.2011.

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Contracting skeletal muscle produces reactive oxygen species (ROS) that have been shown to affect muscle function and adaptation. However, real-time measurement of ROS in contracting myofibers has proven to be difficult. We used amphibian ( Xenopus laevis) muscle to test the hypothesis that ROS are formed during contractile activity in isolated single skeletal muscle fibers and that this contraction-induced ROS formation affects fatigue development. Single myofibers were loaded with 5 μM dihydrofluorescein-DA (Hfluor-DA), a fluorescent probe that reacts with ROS and results in the formation of
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19

Hamann, Jason J., Heidi A. Kluess, John B. Buckwalter, and Philip S. Clifford. "Blood flow response to muscle contractions is more closely related to metabolic rate than contractile work." Journal of Applied Physiology 98, no. 6 (2005): 2096–100. http://dx.doi.org/10.1152/japplphysiol.00400.2004.

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The magnitude of the blood flow response to exercise has been linked to both the contractile work performed and the metabolic cost of the activity. Under certain conditions, contractile work and metabolic cost may be dissociated. This study examined the blood flow response to trains of contractions when contraction duration was manipulated under conditions of similar tension-time indexes (isometric analog of work). Previous investigations have shown that trains of short-duration contractions have a greater ATP utilization, which may result from an augmented ion transport required for muscle ac
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20

Nedachi, Taku, Hideaki Fujita, and Makoto Kanzaki. "Contractile C2C12 myotube model for studying exercise-inducible responses in skeletal muscle." American Journal of Physiology-Endocrinology and Metabolism 295, no. 5 (2008): E1191—E1204. http://dx.doi.org/10.1152/ajpendo.90280.2008.

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Adequate exercise leads to a vast variety of physiological changes in skeletal muscle as well as other tissues/organs and is also responsible for maintaining healthy muscle displaying enhanced insulin-responsive glucose uptake via GLUT4 translocation. We generated highly developed contractile C2C12 myotubes by manipulating intracellular Ca2+ transients with electric pulse stimulation (EPS) that is endowed with properties similar to those of in vivo skeletal muscle in terms of 1) excitation-induced contractile activity as a result of de novo sarcomere formation, 2) activation of both the AMP ki
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21

Lai, Adrian K. M., Andrew A. Biewener, and James M. Wakeling. "Metabolic cost underlies task-dependent variations in motor unit recruitment." Journal of The Royal Society Interface 15, no. 148 (2018): 20180541. http://dx.doi.org/10.1098/rsif.2018.0541.

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Mammalian skeletal muscles are comprised of many motor units, each containing a group of muscle fibres that have common contractile properties: these can be broadly categorized as slow and fast twitch muscle fibres. Motor units are typically recruited in an orderly fashion following the ‘size principle’, in which slower motor units would be recruited for low intensity contraction; a metabolically cheap and fatigue-resistant strategy. However, this recruitment strategy poses a mechanical paradox for fast, low intensity contractions, in which the recruitment of slower fibres, as predicted by the
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22

Spriet, L. L., K. Soderlund, M. Bergstrom, and E. Hultman. "Anaerobic energy release in skeletal muscle during electrical stimulation in men." Journal of Applied Physiology 62, no. 2 (1987): 611–15. http://dx.doi.org/10.1152/jappl.1987.62.2.611.

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The quadriceps femoris muscles of seven men were electrically stimulated under extended anaerobic conditions to quantitate anaerobic energy release and the contribution of the glycolytic system to total ATP production. Muscles were intermittently stimulated 64 times at 20 Hz while leg blood flow was occluded. Each contraction lasted 1.6 s and was followed by 1.6 s of rest. The total contraction time was 102.4 s. Muscle biopsies were taken at rest and following 16, 32, 48, and 64 contractions. The ATP turnover rates during the four 16-contraction periods were 6.12, 2.56, 2.17, and 0.64 mmol X k
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23

Wang, Huiping, Yuxi Guo, Wenjing Yan, et al. "Weakened Contractile Performance and Mitochondrial Respiratory Complex Activity in Skeletal Muscle Improve during Interbout Arousal in Hibernating Daurian Ground Squirrel, Spermophilus dauricus." International Journal of Molecular Sciences 24, no. 21 (2023): 15785. http://dx.doi.org/10.3390/ijms242115785.

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Mammalian hibernation is composed of multiple episodes of torpor bout, separated by phases of interbout arousal. During torpor, the skeletal muscles of mammals are undoubtedly inactive, but it has been proven to mitigate disuse atrophy. While interbout arousal has been implicated in the prevention of muscle atrophy, the underlying mechanisms sustaining muscle contraction remain to be explored. In the present study, Daurian ground squirrels (Spermophilus dauricus) were divided into four groups: pre-hibernation (PRE), torpor (TOR), interbout arousal (IBA), and post-hibernation (POST). The contra
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24

Ushiyama, Junichi, Yoshihisa Masakado, Toshiyuki Fujiwara, et al. "Contraction level-related modulation of corticomuscular coherence differs between the tibialis anterior and soleus muscles in humans." Journal of Applied Physiology 112, no. 8 (2012): 1258–67. http://dx.doi.org/10.1152/japplphysiol.01291.2011.

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The sensorimotor cortex activity measured by scalp EEG shows coherence with electromyogram (EMG) activity within the 15- to 35-Hz frequency band (β-band) during weak to moderate intensity of isometric voluntary contraction. This coupling is known to change its frequency band to the 35- to 60-Hz band (γ-band) during strong contraction. This study aimed to examine whether such contraction level-related modulation of corticomuscular coupling differs between muscles with different muscle compositions and functions. In 11 healthy young adults, we quantified the coherence between EEG over the sensor
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25

Pal, Anupam, and James G. Brasseur. "The Mechanical Advantage of Local Longitudinal Shortening on Peristaltic Transport." Journal of Biomechanical Engineering 124, no. 1 (2001): 94–100. http://dx.doi.org/10.1115/1.1427700.

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Whereas bolus transport along the esophagus results from peristaltic contractions of the circular muscle layer, it has been suggested that local shortening of the longitudinal muscle layer concentrates circular muscle fibers in the region where the highest contractile pressures are required. Here we analyze the mechanical consequences of local longitudinal shortening (LLS) through a mathematical model based on lubrication theory. We find that local pressure and shear stress in the contraction zone are greatly reduced by the existence of LLS. In consequence, peak contractile pressure is reduced
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26

Lowe, D. A., G. L. Warren, D. A. Hayes, M. A. Farmer, and R. B. Armstrong. "Eccentric contraction-induced injury of mouse soleus muscle: effect of varying [Ca2+]o." Journal of Applied Physiology 76, no. 4 (1994): 1445–53. http://dx.doi.org/10.1152/jappl.1994.76.4.1445.

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The objective of this study was to determine the effect of varying extracellular Ca2+ concentration ([Ca2+]o) on eccentric contraction-induced muscle injury. Isolated mouse soleus muscles (n = 64) performed either 20 eccentric or 20 isometric contractions over a 40-min period in a Krebs buffer containing 0.5, 1.25, or 5.0 mM Ca2+. Measurements of contractile function and lactate dehydrogenase accumulation in the buffer were then made every 15 min for 2 h. Prostaglandin E2, leukotriene B4, and tyrosine accumulation in the incubation medium and total muscle [Ca2+] were measured at the end of the
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27

Dalton, Brian H., Brad Harwood, Andrew W. Davidson, and Charles L. Rice. "Triceps surae contractile properties and firing rates in the soleus of young and old men." Journal of Applied Physiology 107, no. 6 (2009): 1781–88. http://dx.doi.org/10.1152/japplphysiol.00464.2009.

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Mean maximal motor unit firing rates (MUFRs) of the human soleus are lower (5–20 Hz) than other limb muscles (20–50 Hz) during brief sustained contractions. With healthy adult aging, maximal MUFRs are 20–40% lower and twitch contractile speed of lower limb muscles are 10–40% slower compared with young adults. However, it is unknown whether the inherently low maximal MUFRs for the soleus are further reduced with aging in association with age-related slowing in contractile properties. The purpose of the present study was to compare the changes in triceps surae contractile properties and MUFRs of
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28

Chen, Ting, Timothy M. Moore, Mark T. W. Ebbert, et al. "Liver kinase B1 inhibits the expression of inflammation-related genes postcontraction in skeletal muscle." Journal of Applied Physiology 120, no. 8 (2016): 876–88. http://dx.doi.org/10.1152/japplphysiol.00727.2015.

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Skeletal muscle-specific liver kinase B1 (LKB1) knockout mice (skmLKB1-KO) exhibit elevated mitogen-activated protein kinase (MAPK) signaling after treadmill running. MAPK activation is also associated with inflammation-related signaling in skeletal muscle. Since exercise can induce muscle damage, and inflammation is a response triggered by damaged tissue, we therefore hypothesized that LKB1 plays an important role in dampening the inflammatory response to muscle contraction, and that this may be due in part to increased susceptibility to muscle damage with contractions in LKB1-deficient muscl
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29

Del Valle, Alejandro, and Christine K. Thomas. "Motor unit firing rates during isometric voluntary contractions performed at different muscle lengths." Canadian Journal of Physiology and Pharmacology 82, no. 8-9 (2004): 769–76. http://dx.doi.org/10.1139/y04-084.

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Firing rates of motor units and surface EMG were measured from the triceps brachii muscles of able-bodied subjects during brief submaximal and maximal isometric voluntary contractions made at 5 elbow joint angles that covered the entire physiological range of muscle lengths. Muscle activation at the longest, midlength, and shortest muscle lengths, measured by twitch occlusion, averaged 98%, 97%, and 93% respectively, with each subject able to achieve complete activation during some contractions. As expected, the strongest contractions were recorded at 90° of elbow flexion. Mean motor unit firi
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30

Bark, H., G. S. Supinski, J. C. Lamanna, and S. G. Kelsen. "Relationship of changes in diaphragmatic muscle blood flow to muscle contractile activity." Journal of Applied Physiology 62, no. 1 (1987): 291–99. http://dx.doi.org/10.1152/jappl.1987.62.1.291.

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The effect of increases in diaphragmatic muscle contractile activity on diaphragm blood flow remains unclear. The present study examined the effect of electrically induced isometric diaphragmatic muscle contractions on diaphragmatic blood flow. Studies were performed on diaphragmatic muscle strips prepared in anesthetized mechanically ventilated dogs. Diaphragmatic contractile activity was quantitated as the tension-time index (TTI) (i.e., the product of tension magnitude and duration). Blood flow to the strip (Qdi) was measured from the volume of the phrenic venous effluent using a drop count
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31

Komalavilas, Padmini, Shyamal Mehta, Christopher J. Wingard, et al. "PI3-kinase/Akt modulates vascular smooth muscle tone via cAMP signaling pathways." Journal of Applied Physiology 91, no. 4 (2001): 1819–27. http://dx.doi.org/10.1152/jappl.2001.91.4.1819.

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Phosphatidylinositol 3-kinase (PI3-kinase) activates protein kinase B (also known as Akt), which phosphorylates and activates a cyclic nucleotide phosphodiesterase 3B. Increases in cyclic nucleotide concentrations inhibit agonist-induced contraction of vascular smooth muscle. Thus we hypothesized that the PI3-kinase/Akt pathway may regulate vascular smooth muscle tone. In unstimulated, intact bovine carotid artery smooth muscle, the basal phosphorylation of Akt was higher than that in cultured smooth muscle cells. The phosphorylation of Akt decreases in a time-dependent manner when incubated w
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32

Lafleur, J., D. Zytnicki, G. Horcholle-Bossavit, and L. Jami. "Declining inhibition in ipsi- and contralateral lumbar motoneurons during contractions of an ankle extensor muscle in the cat." Journal of Neurophysiology 70, no. 5 (1993): 1797–804. http://dx.doi.org/10.1152/jn.1993.70.5.1797.

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1. Motoneurons of pretibial ankle flexor and knee flexor and extensor muscles were recorded intracellularly in chloralose- or pentobarbitone-anesthetized cats during sustained submaximal contractions of either ipsi- or contralateral gastrocnemius medialis muscle (GM). 2. In a majority of ipsilateral motoneurons, a sustained GM contraction elicited inhibitory potentials that quickly subsided before the end of the contraction. An abrupt increase in contractile force could elicit a new series of inhibitory potentials, which declined again in spite of a maintained force level. 3. Contraction-induc
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33

Yu, Ming-Fu, Isabelle Gorenne, Xiaoling Su, Robert S. Moreland, and Michael I. Kotlikoff. "Sodium hydrosulfite contractions of smooth muscle are calcium and myosin phosphorylation independent." American Journal of Physiology-Lung Cellular and Molecular Physiology 275, no. 5 (1998): L976—L982. http://dx.doi.org/10.1152/ajplung.1998.275.5.l976.

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In an effort to further understand the processes underlying hypoxic pulmonary vasoconstriction, we examined the mechanism by which sodium hydrosulfite (Na2S2O4), a potent reducing agent and oxygen scavenger, induces smooth muscle contraction. In rat pulmonary arterial strips, sodium hydrosulfite (10 mM) induced contractions that were 65.9 ± 12.8% of the response to 60 mM KCl ( n = 9 segments). Contractions were not inhibited by nisoldipine (5 μM) or by repeated stimulation with caffeine (10 mM), carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (10 μM), or cyclopiazonic acid (10 μM), all of
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34

Teplov, A. Yu, A. M. Farkhutdinov, S. N. Grishin, M. M. Minnebaev, and V. I. Torshin. "Possible involvement of adenosine triphosphate in the mechanisms of protein sensibilization effect on the functional properties of the diaphragm and skeletal muscles." Kazan medical journal 93, no. 1 (2012): 113–16. http://dx.doi.org/10.17816/kmj2159.

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Aim. To study the effect of adenosine triphosphate on the contractile function and non-quantum secretion of acetylcholine at the endplate zone (H-effect) of isolated mouse muscles on the background of protein sensibilization. Methods. The experiments were performed on white mice. Sensibilization was carried out by ovalbumin with an aluminum hydroxide gel. Mechanomyography studies were performed on isolated preparations of the diaphragm and of two leg muscles in isometric conditions. The contractions were recorded by a photoelectric converter. In order to study the condition of the postsynaptic
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35

Beaty, O. "Arterial blood pressure control during hindlimb and forelimb contraction in the dog." American Journal of Physiology-Heart and Circulatory Physiology 248, no. 5 (1985): H678—H687. http://dx.doi.org/10.1152/ajpheart.1985.248.5.h678.

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This study examined the differential reflex cardiovascular responses evoked by separate contractions of the right hindlimb and forelimb and established the mechanism of a regional reflex vasodilation associated with hindlimb skeletal muscle contraction. The two groups of skeletal muscle were contracted separately by electrical stimulation (2-48 Hz) of the peripheral motor nerves. The left nonexercising hindlimb was perfused at constant flow. All blood pressure-regulating mechanisms were intact. Arterial blood pressure (ABP), left nonexercising hindlimb perfusion pressure (HLPP), and heart rate
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36

Locke, Marius, and Stephanie A. Salerno. "Ovariectomy alters lengthening contraction induced heat shock protein expression." Applied Physiology, Nutrition, and Metabolism 45, no. 5 (2020): 530–38. http://dx.doi.org/10.1139/apnm-2019-0212.

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Estrogen appears to play a role in minimizing skeletal muscle damage as well as regulating the expression of the protective heat shock proteins (HSPs). To clarify the relationship between estrogen, muscle HSP content, and muscle damage, tibialis anterior (TA) muscles from ovary-intact (OVI; n = 12) and ovariectomized (OVX; 3 weeks, n = 12) female Sprague–Dawley rats were subjected to either 20 or 40 lengthening contractions (LCs). Twenty-four hours after stimulation, TA muscles were removed, processed, and assessed for HSP25 and HSP72 content as well as muscle (damage) morphology. No differenc
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Lou, F., N. A. Curtin, and R. C. Woledge. "Elastic energy storage and release in white muscle from dogfish scyliorhinus canicula." Journal of Experimental Biology 202, no. 2 (1999): 135–42. http://dx.doi.org/10.1242/jeb.202.2.135.

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The production of work by the contractile component (CC) and the storage and release of work in the elastic structures that act in series (the series elastic component, SEC) with the contractile component were measured using white muscle fibres from the dogfish Scyliorhinus canicula. Heat production was also measured because the sum of work and heat is equivalent to the energy cost of the contraction (ATP used). These energy fluxes were evaluated in contractions with constant-velocity shortening either during stimulation or during relaxation. The muscle preparation was tetanized for 0.6 s and
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38

Yoshinaga, M., Y. Chijiiwa, T. Misawa, N. Harada, and H. Nawata. "EndothelinB receptor on guinea pig small intestinal smooth muscle cells." American Journal of Physiology-Gastrointestinal and Liver Physiology 262, no. 2 (1992): G308—G311. http://dx.doi.org/10.1152/ajpgi.1992.262.2.g308.

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We investigated the binding characteristics of the endothelin (ET) receptor and the mechanism by which ET induces contraction of longitudinal smooth muscle cells of the guinea pig small intestine by using vasoactive intestinal contractor (VIC), a mouse variant of ET-2. A functional receptor for VIC was found to exist on longitudinal smooth muscle cells. These cells showed a similar binding of and contractile response to ET-1, ET-2, and ET-3. Inhibitors of both intracellular and extracellular Ca2+ movement attenuated the VIC-induced contraction of longitudinal smooth muscle cells. These results
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39

Giuriato, Gaia, Stephen J. Ives, Cantor Tarperi, et al. "Timed synchronization of muscle contraction to heartbeat enhances muscle hyperemia." Journal of Applied Physiology 128, no. 4 (2020): 805–12. http://dx.doi.org/10.1152/japplphysiol.00898.2019.

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Blood flow (BF) to exercising muscles is susceptible to variations of intensity, and duration of skeletal muscle contractions, cardiac cycle, blood velocity, and vessel dilation. During cyclic muscle activity, these elements may change proportionally with or without direct optimal temporal alignment, likely influencing BF to active muscle. Ideally, the pulsed delivery of blood to active muscle timed with the inactive phase of muscle duty-cycle would enhance the peak and average BF. To investigate the phenomenon of muscle contraction and pulse synchronicity, electrically evoked muscle contracti
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Brozinick, J. T., G. J. Etgen, B. B. Yaspelkis, and J. L. Ivy. "The effects of muscle contraction and insulin on glucose-transporter translocation in rat skeletal muscle." Biochemical Journal 297, no. 3 (1994): 539–45. http://dx.doi.org/10.1042/bj2970539.

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The effect of electrically induced muscle contraction, insulin (10 m-units/ml) and electrically-induced muscle contraction in the presence of insulin on insulin-regulatable glucose-transporter (GLUT-4) protein distribution was studied in female Sprague-Dawley rats during hindlimb perfusion. Plasma-membrane cytochalasin B binding increased approximately 2-fold, whereas GLUT-4 protein concentration increased approximately 1.5-fold above control with contractions, insulin, or insulin + contraction. Microsomal-membrane cytochalasin B binding and GLUT-4 protein concentration decreased by approx. 30
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41

Santos, Rute, Maria João Valamatos, Pedro Mil-Homens, and Paulo A. S. Armada-da-Silva. "Effect of Knee Angle, Contractile Activity, and Intensity of Force Production on Vastus Lateralis Stiffness: A Supersonic Shear Wave Elastography Pilot Study." Sports 12, no. 8 (2024): 211. http://dx.doi.org/10.3390/sports12080211.

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Supersonic shear image (SSI) ultrasound elastography provides a quantitative assessment of tissue stiffness using the velocity of shear waves. SSI’s great potential has allowed researchers in fields like biomechanics and muscle physiology to study the function of complex muscle groups in different conditions. The aim of this study is to use SSI to investigate changes in the stiffness of the vastus lateralis (VL) muscle as a consequence of passive elongation, isometric contraction, and repeated muscle activity. In a single session, 15 volunteers performed a series of isometric, concentric, and
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Sarna, S. K. "Gastrointestinal longitudinal muscle contractions." American Journal of Physiology-Gastrointestinal and Liver Physiology 265, no. 1 (1993): G156—G164. http://dx.doi.org/10.1152/ajpgi.1993.265.1.g156.

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The patterns of longitudinal muscle contractions of the stomach and the small intestine and their relationship with circular muscle contractions during the fasting and the fed state were investigated in conscious dogs. In the stomach, the longitudinal muscle contracted in a 1:1 relationship with the circular muscle contractions. There was no significant difference between the frequency, duration, and time of onset of gastric longitudinal and circular muscle contractions, and their amplitudes were significantly correlated with each other. In the small intestine when the circular muscle contract
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Wigmore, D. M., B. M. Damon, D. M. Pober, and J. A. Kent-Braun. "MRI measures of perfusion-related changes in human skeletal muscle during progressive contractions." Journal of Applied Physiology 97, no. 6 (2004): 2385–94. http://dx.doi.org/10.1152/japplphysiol.01390.2003.

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Although skeletal muscle perfusion is fundamental to proper muscle function, in vivo measurements are typically limited to those of limb or arterial blood flow, rather than flow within the muscle bed itself. We present a noninvasive functional MRI (fMRI) technique for measuring perfusion-related signal intensity (SI) changes in human skeletal muscle during and after contractions and demonstrate its application to the question of occlusion during a range of contraction intensities. Eight healthy men (aged 20–31 yr) performed a series of isometric ankle dorsiflexor contractions from 10 to 100% m
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44

James, Arlene N., James P. Ryan, and Henry P. Parkman. "Inhibitory effects of botulinum toxin on pyloric and antral smooth muscle." American Journal of Physiology-Gastrointestinal and Liver Physiology 285, no. 2 (2003): G291—G297. http://dx.doi.org/10.1152/ajpgi.00296.2002.

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Botulinum toxin injection into the pylorus is reported to improve gastric emptying in gastroparesis. Classically, botulinum toxin inhibits ACh release from cholinergic nerves in skeletal muscle. The aim of this study was to determine the effects of botulinum toxin on pyloric smooth muscle. Guinea pig pyloric muscle strips were studied in vitro. Botulinum toxin type A was added; electric field stimulation (EFS) was performed every 30 min for 6 h. ACh (100 μM)-induced contractile responses were determined before and after 6 h. Botulinum toxin caused a concentration-dependent decrease of pyloric
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Raiteri, Brent J., Andrew G. Cresswell, and Glen A. Lichtwark. "Three-dimensional geometrical changes of the human tibialis anterior muscle and its central aponeurosis measured with three-dimensional ultrasound during isometric contractions." PeerJ 4 (July 28, 2016): e2260. http://dx.doi.org/10.7717/peerj.2260.

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Background.Muscles not only shorten during contraction to perform mechanical work, but they also bulge radially because of the isovolumetric constraint on muscle fibres. Muscle bulging may have important implications for muscle performance, however quantifying three-dimensional (3D) muscle shape changes in human muscle is problematic because of difficulties with sustaining contractions for the duration of anin vivoscan. Although two-dimensional ultrasound imaging is useful for measuring local muscle deformations, assumptions must be made about global muscle shape changes, which could lead to e
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Selseth, Angie, Marilyn Dayton, Mitchell L. Cordova, Christopher D. Ingersoll, and Mark A. Merrick. "Quadriceps Concentric EMG Activity Is Greater than Eccentric EMG Activity during the Lateral Step-Up Exercise." Journal of Sport Rehabilitation 9, no. 2 (2000): 124–34. http://dx.doi.org/10.1123/jsr.9.2.124.

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Purpose:To analyze vastus medialis obliquus (VMO) and vastus lateralis (VL) muscle activity during the concentric and eccentric phases of a lateral step-up exercise.Design:Repeated-measures. Dependent variable: the integrated electromyogram measured as a percentage of the maximal voluntary isometric contraction of the VMO and VL muscles. Independent variable: muscle contraction with 2 levels (concentric and eccentric).Subjects:Twenty-three volunteers with no previous history of knee surgery or anterior knee pain.Methods:Surface electrodes were positioned over the VMO and VL, and electromyograp
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47

Kristiansen, S., S. Asp, and E. A. Richter. "Decreased muscle GLUT-4 and contraction-induced glucose transport after eccentric contractions." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 271, no. 2 (1996): R477—R482. http://dx.doi.org/10.1152/ajpregu.1996.271.2.r477.

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Eccentric exercise causes muscle damage and decreased muscle glycogen and glucose transporter isoform (GLUT-4) protein content. We investigated whether the contraction-induced increase in skeletal muscle glucose transport and muscle performance is affected by prior eccentric contractions. The calf muscles from rats were stimulated for eccentric (EC) or concentric (CC) contractions or were passively stretched (ST). Muscles from unstimulated control (CT) rats were also studied. Two days later, all rats had their isolated hindlimbs perfused either at rest or during 15 min of isometric muscle cont
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48

Maganaris, Constantinos N., Vasilios Baltzopoulos, and Anthony J. Sargeant. "Repeated contractions alter the geometry of human skeletal muscle." Journal of Applied Physiology 93, no. 6 (2002): 2089–94. http://dx.doi.org/10.1152/japplphysiol.00604.2002.

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The aim of this study was to investigate the effect of repeated contractions on the geometry of human skeletal muscle. Six men performed two sets ( sets Aand B) of 10 repeated isometric plantarflexion contractions at 80% of the moment generated during plantarflexion maximal voluntary contraction (MVC), with a rest interval of 15 min between sets. By use of ultrasound, the geometry of the medial gastrocnemius (MG) muscle was measured in the contractions of set A and the displacement of the MG tendon origin in the myotendinous junction was measured in the contractions of set B. In the transition
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49

Beaty, O. "Carotid sinus and blood pressure control during hindlimb and forelimb contractions." American Journal of Physiology-Heart and Circulatory Physiology 248, no. 5 (1985): H688—H694. http://dx.doi.org/10.1152/ajpheart.1985.248.5.h688.

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Arterial blood pressure (ABP) regulation during exercise involves in part medullary interaction of afferent information from contracting skeletal muscles and the major baroreceptors. This study examined in chloralose-anesthetized dogs the role of the carotid sinus baroreceptors in modulating reflex changes in ABP, nonexercising hindlimb skeletal muscle vascular resistance, and heart rate (HR) evoked by two separately contracting (4, 16, and 48 Hz) groups of skeletal muscle, the right hindlimb and forelimb. When arterial and cardiopulmonary baroreceptor afferent information was interrupted, hin
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Young, J. C., T. G. Kurowski, A. M. Maurice, R. Nesher, and N. B. Ruderman. "Polymyxin B inhibits contraction-stimulated glucose uptake in rat skeletal muscle." Journal of Applied Physiology 70, no. 4 (1991): 1650–54. http://dx.doi.org/10.1152/jappl.1991.70.4.1650.

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Glucose transport in muscle is activated by contractile activity, an effect that persists in the postexercise state. Polymyxin B, a cyclic decapeptide antibiotic, inhibits the stimulation of glucose uptake in isolated muscle by contractile activity but also decreases tension development in electrically stimulated muscle. The purpose of this study was to determine whether polymyxin B also inhibits contraction-stimulated glucose uptake after in vivo administration of the drug and to examine the relationship between the effects of polymyxin B on tension development and its effects on contraction-
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