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Contractile properties of slow and fast skeletal muscles from protease activated receptor‐1 null mice
Author(s) -
Sitparan Paran K.,
Pagel Charles N.,
Pinniger Gavin J.,
Yoo H.J.,
Mackie Eleanor J.,
Bakker Anthony J.
Publication year - 2014
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.24256
Subject(s) - endocrinology , medicine , stimulation , soleus muscle , skeletal muscle , receptor , contraction (grammar) , chemistry , muscle contraction , anatomy , biology
: 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