[Effect of stress on myocardial stretching, Starling's mechanism and resistance to hypoxia].

The effect of emotional-painful stress (EPS) on myocardial tensility, contractility and resistance to hypoxia and excess of calcium was studied on isolated rat atrium. It was established that after EPS the myocardial tensility decreased, Starling's curve was depressed and the efficiency of Starling's mechanism fell. The above-mentioned post-stress alterations of myocardial contractility were accompanied by a decrease in the myocardial resistance to hypoxia and excess of calcium in stress-exposed animals. These data combined suggest that the revealed stress-induced alterations of atrial tensility and contractility are an integrative result of a failure of the energy-supplying and calcium-transport systems in cardiomyocytes. The established stress-induced decrease in myocardial resistance to hypoxia and excess of calcium may contribute to the heart muscle damage in coronary and other circulatory diseases related to energy shortage, and increased calcium content in cardiomyocytes.