Myocyte cellular hyperplasia and myocyte cellular hypertrophy contribute to chronic ventricular remodeling in coronary artery narrowing-induced cardiomyopathy in rats.

Abstract

To determine whether cardiac failure produced by chronic coronary artery stenosis was associated with the activation of myocyte cellular hyperplasia in the myocardium, the changes in number and size of left ventricular myocytes were measured in rats 3 months after surgery. The hypertrophied left ventricle was found to possess 44%, 32%, 49%, and 48% fewer mononucleated, binucleated, trinucleated, and tetranucleated myocytes, respectively. In contrast, the hypertrophied right ventricle contained 1.49 x 10(6) more myocytes as a result of a 2.1-fold, 1.4-fold, and 1.4-fold increase in mononucleated, binucleated, and tetranucleated myocytes. Myocyte cell volume was seen to increase 49% and 21% in left and right ventricular myocytes, respectively. The process of myocyte cellular hyperplasia in the right ventricular myocardium was accompanied by capillary proliferation, and these events were responsible for the parallel addition of newly formed cells and capillaries within the wall and mural thickening. Moreover...