[Cyclic AMP system in muscle tissue during prolonged hypokinesia].

Constituents of cAMP system were studied in prolonged hypokinesia (70--75 days) and within the period of readaptation of muscular tissue in rats. Content of cAMP as well as activities of adenylate cyclase and phosphodiesterase were increased in muscles at the initial period of limited mobility (especially, within the first 5 days). Within the period of so-called "adaptation" (during the first 24--37 days) content of cAMP and activity of both enzymes were practically similar to control values. Distinct decrease in cAMP content, activation of phosphodiesterase and decrease in stimulating effect of adrenaline on adenylate cyclase activity were observed within the first 70 days of the experiment. Pronounced normalization of the patterns studied occurred within the period of readaptation.