Contractile properties of slow and fast skeletal muscles from protease activated receptor‐1 null mice |
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Authors: | Paran K Sitparan MSc Charles N Pagel PhD Gavin J Pinniger PhD HJ Yoo MSc Eleanor J Mackie Dr Med Vet Anthony J Bakker PhD |
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Institution: | 1. School of Anatomy, Physiology and Human Biology, M311, The University of Western Australia, , Crawley, WA, 6009 Australia;2. Faculty of Veterinary Science, The University of Melbourne, , Parkville, VIC, 3010 Australia |
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Abstract: | Introduction: Protease‐activated receptors (PARs) may play a role in skeletal muscle development. We compared the contractile properties of slow‐twitch soleus muscles and fast‐twitch extensor digitorum longus (EDL) muscles from PAR‐1 null and littermate control mice. Methods: Contractile function was measured using a force transducer system. Fiber type proportions were determined using immunohistochemistry. Results: Soleus muscles from PAR‐1 null mice exhibited longer contraction times, a leftward shift in the force–stimulation frequency relationship, and decreased fatiguability compared with controls. PAR‐1 null soleus muscles also had increased type 1 and decreased type IIb/x fiber numbers compared with controls. In PAR‐1 null EDL muscles, no differences were found, except for a slower rate of fatigue compared with controls. Conclusions: The absence of PAR‐1 results in a slower skeletal muscle contractile phenotype, likely due to an increase in type I and a decrease in type IIb/x fiber numbers. Muscle Nerve 50: 991–998, 2014 |
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Keywords: | Ca2+ calcium contraction damage development eccentric exercise fatigue force inflammation injury motor mouse myoblast myotube necrosis nerve neuron primary fibers proteinase regeneration secondary fibers synapse thrombin trypsin |
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