Stress damage to nonischemic divisions of the heart in experimental infarction and its prevention.

Recently, it has been shown that nonischemic parts of the heart in myocardial infarction were separated from ischemic damaged ones by a sharp border zone. In this connection, the disturbance of contractile function of the myocardium of nonischemic parts is suggested to result from the infarction-concomitant emotional-painful stress. In order to test this assumption, the contractile function of the right auricle, which is an a priori nonischemic heart division, was studied in rats subjected to myocardial infarction of the left ventricle. In the study of the isolated auricle the following facts were established: 1 day after the induced infarction the atrial myocardium shows reduced extensibility, depression of the Starling curve, a concomitant approximately twofold decrease of the maximal systolic tension, and a reduced myocardial resistance to hypoxia and calcium excess. This complex of shifts, first, is completely reproduced without myocardial infarction by emotional-painful stress and, second, can be prevented to a considerable extent by propranolol indicating that it is essentially stress induced. In infarction, these above said stress-induced disturbances of the contractile function of nonischemic divisions of the heart were found to be prevented or limited by factors stabilizing the membranous lipid bilayer of cardiomyocytes, i.e., by antioxidant ionol, by nicotinamide, a lipase inhibitor, and by chloroquine, a phospholipase inhibitor. The aspects of application of these factors for the therapy of ischemic heart disease requires further studies.