[Adaptation to short-term stressor factors increases calcium pump activity in sarcoplasmic reticulum and decreases the rate of its inactivation during autolysis].

Effects of long-term immobilization stress and adaptation to short-term stressory actions on Ca2(+)-transport system were studied in sarcoplasmic reticulum (SR) of rat myocardium. The stress inhibited the rate of Ca2+ transport in SR, while adaptation not only optimized the Ca2(+)-pump functions but prevented the stress-induced impairments of its functions. After stress resistance of Ca2(+)-pump to endogenous impairing factors (in autolysis) was decreased 2-3-fold, whereas adaptation increased the SR membrane stability so distinctly that after simultaneous stress the membrane stability was maintained at the level which-was 2.5-times higher as compared with controls. Long-term stress caused also the higher output of Ca+2 from intracellular stores as compared with controls, while during adaptation and simultaneous stress and adaptation the loss of Ca2+ was practically absent. Protective effects of adaptation to short-term stressory actions on the Ca2(+)-transport system of cardiomyocytes are discussed.