Prolonged passive stretch of rat soleus muscle provokes an increase in the mRNA levels of the muscle regulatory factors distributed along the entire length of the fibers

摘要: The mRNA levels of the adult and neonatal sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPases (SERCA1a SERCA1b, respectively) those muscle regulatory factors (MRFs: myoD, myf-5, myogenin, MRF4) have been assessed by RT PCR in rat soleus muscles immobilized for 3 days an extended position (passive stretch). transcript level fast type SERCA1a Ca(2+)-transport ATPase decreased to half its normal value, whereas that SERCA1b isoform increased 5-fold above control stretched muscles. Immunostaining cross sections showed fraction fibers expressing protein was evenly along length indicating a transformation occurred slow ones. MRFs were elevated 3- 6-fold distributed However controls these transcripts more abundant at both ends muscle. stretch myoD immunocytochemistry expression number nuclei it practically undetectable this method Western blotting did not indicate significant stretch-induced increase myogenin protein, spite fact tended show myogenin-positive as compared controls. These data after passive central terminal parts adapt similarly increasing MRFs, decreasing overall SERCA1-type partially re-establishing mode alternative SERCA1 splicing resulting SERCA1b/1a ratio.