[Effect of hypokinesia and physical loading on the ultrastructure of cardiac myocytes].

The experiments were carried out in rabbits and rats during 1--7.5 months. They demonstrated increasing disturbances in ultrastructure of the protein synthesizing myocardiocyte apparatus. The major and most dangerous disorder is the deficiency in the myocardial apparatus, which is, evidently, the main cause in the reduction of the cardiac functional reserves. Externally, similar reaction of the organism in response to loading (treadmill)--deep fatigue--produces diverse ultrastructural changes in the myocardium depending on the initial adaptive level to motor activity. In rabbits, having satisfactory adaptation to motor activity, the loading (treadmill) results, mainly, in exhaustion of their energy storage. In disadapted animals it produces dangerous lesions in the contractile apparatus of the cardial myocytes.