[Changes in the physico-chemical properties of contractile and regulatory proteins in muscles of different types during overload and readaptation].

After 15-day exposure to +5 Gx the rate of superprecipitation, Mg2+-ATPase activity and actomyosin ATPase of slow muscles (m. soleus and medial head of m. triceps brachii) of white rats increased greatly. In actomyosin of fast muscles (m. brachialis and m. extensor digitorum longus) the exposure induced weaker and opposite changes in the superprecipitation rate and Mg2+-ATPase activity. The changes in actomyosin of the fast muscles were associated with shifts only in regulatory components while those of the slow muscles were produced by shifts in contractile proteins as well. This provided for a better recovery of the initial value of the superprecipitation rate and Mg2+-ATPase activity of actomyosin of the fast muscles a month after the exposure.