[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.

[Emotional stress and extracardiac regulation].

Chronic experiments in rabbits and rats revealed that, when sympathetic influences on the heart prevail during emotional stress, reduce the heart electric stability, induce disorders in the heart rhythm and lead to arterial hypertension. Prevailing of parasympathetic influences, on the contrary, augments the heart electric stability, interferes with an increase in the catecholamines content and prevents structural lesions in the myocardium. Arterial hypertension is absent, at that.

[Sympathetic regulation of heart rhythm under the effect of delta sleep peptide and its deficiency].

In acute experiments on 16 rabbits we've studied effects of delta-sleep peptide and its deficiency on the irritation of the stellate ganglion. It has been revealed, that peptide injection (60 nM/kg) produces lowered positive chronotropic effect and elongated response development during irritation of this ganglion. Administration of antiserum to delta-sleep peptide (T = 1:3000) causes opposite effect: enhances sympathetic response during irritation of the stellate ganglion.

[Delta sleep-inducing peptide as a modulator of mediators acting on the heart].

Experiments on 51 isolated rabbit hearts have documented, that delta sleep-inducing peptide (6 X 10(-6) M/l) has a modulating effect on the mediators influencing the heart. This peptide enhances negative chronotropic effect of acetylcholine (1 X 10(-6) M/l) and decreases positive chronotropic effect of noradrenaline (1 X 10(-6) M/l). Such effect may be one of mechanisms of changes in the extracardiac regulation on the heart influenced by this peptide.