The dynamics of arterial blood pressure and some data of cardiac contractility in rabbits with vasorenal hypertension were investigated in 4 seasons of the year. Simultaneously, the effects of verapamil on the said data were studied in rabbits with vasorenal hypertension (verapamil was administered at 12 and 18 h during last 2 weeks of experiment). In different seasons the definite differences in therapeutic effect of verapamil depending on the time of its administration were revealed.

It was shown in experiments on intact male rabbits that moderate-altitude hypoxia causes over-stress of the cardiomyocyte energy-producing apparatus in unadapted animals. Acute infusion of verapamil leads to a high mortality rate among these animals, whereas among aborigines of moderate and low altitudes as well as among animals living in the planes mortality in acute verapamil infusion does not exceed 30%.

Some data of intact rabbits' cardiovascular system (arterial blood pressure, data of real and maximum function of heart ventricles) were investigated in different seasons of the year. It was revealed, that in winter the cardiovascular system functions with definite degree of overstrain, and in summer these data are on the lower level of the norm. Correlative analysis showed that in summer the degree of synchronization of the function of cardiovascular system drops and this can open wide possibilities for it's adaptation to variable conditions.