[Characteristics of ultrastructure of the myocardium of rats with different resistance to oxygen deficiency after acute and periodic effects of hypoxia].

In experiments on rats with different resistance to oxygen deficiency (high-resistant--HR, and low-resistant LR animals) the myocardium ultrastructure of nonadapted and adapted rats was studied. It was shown that there were more glycogen granules and lipid drops initially in cardiomyocytes of nonadapted HR animals in comparison with LR ones. After a long-term adaptation to hypoxia the hypertrophia and hyperplasia of mitochondria, the nucleus and endoplasmatic reticulum hypertrophy were observed. Moreover, the increase of glycogen and lipids content was more pronounced in the myocardium of LR rats. Besides, the activation of protein-synthesizing processes was observed not only as a result of long-term adaptation, but also after single acute hypoxic effect. The results of submicroscopic cardiomyocyte studies of HR and LR rats are in good correlation with the peculiarities of energetic metabolism.