[Quantitative ultrastructural characteristics of mitochondria and myofibrils in the myocardium in chronic hemodynamic overload]

Abstract

Stereological morphometry was used to determine ultrastructural changes of the myocardium in the course of well defined chronic hemodynamic overload. Overload was induced in the hearts of rabbits by perforation of aortic valves. Relative volumes of mitochondria, myofibrils were measured in tissue samples taken from subendocardial and subepicardial region of the left ventricle. In the course of developing hypertrophy relative volume of mitochondria significantly increased as well as volume ratio Mi/Mf, while those of myofibrils decreased. Increased volume of mitochondria prolonged during the period of developed hypertrophy and its normalization occurred in the hypertrophy regression. Failure of the heart was characterized by increased volume of mitochondria and decrease those of myofibrils. Comparison of given morphometric data in subendocardium and subepicardium of the left ventricle did not find regional differences in subcellular composition of cardiomyocytes in the course of chronic hemodynamic overload.