[Contractile function, extracardiac regulation and morphological changes in the hearts of rats in the dynamics of a long-term continuously acting stressor situation].

24 hrs of the overpopulation stress effect induced a set of shifts typical for an acute stress syndrome in rats. Within 5 days the organism mobilizes the cholinergic stress-limiting system functioning for 15 days, limiting and normalizing the contractile function (CF) of the heart, and eliminating the contracture damages of the myocardium on the 30th day. Starting from the 30th day of the stress effect, adrenergic features of the extracardiac regulation (ER) re pear, the CF parameters increase, cardiac resistance to isometric loads decreases insignificantly, acute alterations appear in the myocardium (the 60th day). The ER shift towards sympatheticotonia is substituted by increased vagal effects on the heart (the 120th day). The wave-like oscillations of the tonus of the vegetative nervous system and CF of the heart occur against the background of appearing and accumulating small foci of cardiosclerosis.