Changes in myosin heavy chain isoforms during chronic low-frequency stimulation of rat fast hindlimb muscles. A single-fiber study.

摘要: Fast-twitch rat muscles contain three fast myosin heavy chains (HC) which can be separated by density gradient gel electrophoresis. Their mobility increases in the order of HCIIa less than HCIId HCIIb. In contrast to rabbit, where chronic low-frequency nerve stimulation induces a fast-to-slow conversion, for up 56 days does not lead appreciable relative concentration slow chain HCI fast-twitch muscles. However, muscle evoke rearrangement isoform pattern with progressive decrease HCIIb and HCIId. As judged from time course extent these transitions, it appears that is an intermediate form between HCIIa. Single-fiber analyses normal make possible assign isoforms histochemically defined fiber types IIB, IID, IIA. The stimulation-induced transformations produce numerous hybrid fibers displaying more one isoform. Some transforming four different isoforms.