[Variations in morphologic alterations in the hearts of white rats during adaptation to different types of physical loads].

While adapting to physical loadings various in their character, most of rats develop a moderate hypertrophy in the right cardiac ventricle without any noticeable changes in the organ's mass. ECG dynamics is positive. Myocardial hypertrophy, at the expense of increasing mass of the left ventricle, is most regularly observed in animals subjected to forced endurance training (daily swimming); less regularly--if the loading is applied with intervals (swimming every other day) and is practically absent in rats performing work with force application. Pathological ECG changes occur more often on the background of myocardial hypertrophy and are brought about by dystrophic disorders in muscular fibres, their focal micronecrosis, by edema of the interstitial and perivascular tissue.