[Quantitative evaluation of ultrastructural changes in the rat myocardium during prolonged hypokinesia]

It was morphometrically shown that during 120-day hypokinesia chromatin redistribution was similar in nuclei of myocardial cells of the ventricles of the rat heart. Quantitative rearrangements in the mitochondrial apparatus of cells were of different pattern. On the 14th hypokinetic day the number of mitochondria increased and their size decreased; on the 30th day their size increased and their number decreased; on the 45 and 60th day the number and size of mitochondria returned to the normal; on the 120th hypokinetic day the number and size of mitochondria were higher than the control. Throughout the 120-day experimental the ratio of the total area of mitochondria to the total area of myofibers varied periodically and by the end of the experimental the mitochondrial area increased. Thus, it is obvious that by the 120th hypokinetic day myocardial changes increased indicating a new level of cardiac activity during prolonged hypokinesia. Quantitative changes in the organelles of the myocardium of the left ventricle were more significant than those of the right ventricle during the exposure.