Comparative evaluation of the effect of preliminary adaptation of the body to moderate physical loading and brief stress exposures on heart contractile function disorders in long-term stress

The effect of repeated emotional-painful stress stimuli and repeated moderate exercise (swimming) on cardiac resistance to long-term emotional-painful stress (EPS) was studied in Wistar rats. Adaptation to repeated exercises was found to significantly increase tension developed by the myocardium of an isolated auricle and myocardial resistance to hypoxia and excessive calcium, but it could not prevent the EPS-induced depression of contractility. Adaptation to short-term stress on the contrary, did not significantly affect myocardial tension and cardiac resistance to hypoxia and excessive calcium, but it completely prevented the long-term EPS-induced depression and considerably reduced the stress-potentiating effect on the development of calcium and hypoxic contractures. Therefore, adaptation to stressful effects proper, rather than moderate exercise, can build up heart resistance to damaging stress effects.