[Physiological approaches to enhancing cardiac resistance in emotional stress]

The role of parasympathic effects, graded motor activity, positive emotions, and delta-sleep peptide in enhancing the resistance of cardiac performance in experimental emotional stress was studied in chronic rabbit experiments. The prevalence of parasympathic effects was demonstrated to increase cardiac electric stability and to prevent the elevation of catecholamine levels and the development of myocardial structural damages during stress. A moderate motor activity was found to lead to the session of ventricular extrasystole occurring in stress due to decreases in the myocardial levels of epinephrine with its high levels remaining in blood. Ventricular extrasystole also disappeared after activation of the positive emotional centers of the hypothalamus and after administration of delta-sleep peptide normalizing the electrical stability of the heart in emotional stress.