The effect of activity on the rat skeletal muscle contractile apparatus
In 35 m/min running rats the myosin heavy chains have a faster turnover rate in all three types of skeletal muscle fibers. In the ease of 95 m/min running rats the myosin heavy chains turned over faster only in fast-glyeolytie and fast-oxidative-
glycolytie type of muscle fibers. The turnover rate of myosin light chains remained at the control animals’ level. 95 mlmin running exercise caused significant alterations in myosin heavy chain isoforms percentage —the decrease in type I and IIb of myosin heavy chain isoforms and the increase in type lla/d of myosin heavy chain isoforms. At the same time the turnover rate of the total myosin heavy chain fraction showed the inerease.The ratio of myosin heavy chains and actin decreased in
glycolytie type of muscle fibers in 95 mlmin running rats.