Proliferative activity of cadriomyocytes in chronic hypercholesterolemia.

We studied proliferative activity of cardiomyocytes (using proliferation marker Ki-67) and compared it with their total number in the heart under conditions of experimental chronic hypercholesterolemia and its combination with hypothyroidism. It was found that Ki-67-positive cells are primarily located in the subepicardial layer near the heart base in both intact and experimental animals. Replicative cardiomyocyte pool in intact rats constituted 1.67 ± 0.33‰ of the total cardiomyocyte population; after 68-day atherogenic diet with exogenous cholesterol alone, the replicative cardiomyocyte pool decreased by 16 % (to 1.40 ± 0.24‰). Treatment with mercazolil against the background of exogenous cholesterol increased this parameter by 40 % (to 2.33 ± 0.88‰). Changes in replicative activity of cardiomyocytes correlated with their total number in the heart and organ weight. We conclude that replicative cardiomyocyte pool primarily includes non-terminally differentiated cardiomyocytes (small mononuclear cardiomyocytes) and their proliferation maintains the total number of cardiomyocytes in the heart under conditions of cytopathic influences and provides the basis for physiological and reparative regeneration of the myocardium.