[Hormonal regulation of the heart in aging]

It was established in experiments on adult (8--12 month) and old (26--32 month) rats that in ageing the sensitivity of the cardiovascular system to certain hormones--adrenaline, vasopressin, insulin, thyroxine, estradiol dipropionate--grows while its reactivity to them diminishes. The administration of these hormones causes significant changes in hemodynamics and myocardial contractility. Adrenaline and thyroxine lead to an increase in the blood minute and stroke volume, arterial pressure, cardiac index and left ventricular work index, maximum rate of intraventricular pressure growth, maximum rate of myocardial fiber shortening, and in the contrastility index. Vasopressin and insulin cause a decrease in the indices of general hemodynamics. The increased sensitivity of the heart to hormones at old age and diminution of its reactivity lead to prolonged, protracted reactions of the cardiovascular system in elderly and old individuals.