RESTRUCTURING OF SKELETAL MUSCLE, LUNG AND HEART TISSUES OF RATS UNDER HYPOXIA TRAINING

We studied some specific features of the changes in mor- pho- and stereometric characteristics of the ultrastructure of tissues of lungs, heart, and muscles, their capillarization, and the mitochondrial apparatus of cells in adult male Wistar rats under long-term physical loads. It is shown that the influence of a sustained training accompanied by the development of exercise-induced hypoxia on the structural readjustments of tissues of muscles, lungs, and myocardium can be conditionally divided into 2 groups: with destructive and compensatoryadaptive features. The changes with destructive character include, firstly, those of the ultrastructure of biological bar- riers such as, in particular, hyperhydration of barriers on the whole and their separate layers, which deteriorates the conditions of oxygen diffusion; second, the destructive changes in mitochondria (it increased the number of damaged lung organelles by 4.1 times, in the heart - at 4.5-5.5 times depending on subpopulations and in muscle - by 3.5-12.2 times also depending on the subpopulation of mitochondria), which are accompanied by a decrease in the energy potential of the mitochondrial apparatus, are observed. To the changes with compensatory-adaptive character, we refer an increase in the number of functioning capillaries (by 80% in the gastrocnemius muscle and by 60% in the myocardium), which prevents the development of secondary tissue hypoxia; intensification of pinocytosis in endotheliocytes; activation of mitochondrial morphogenesis, which was accompanied by an increase of the number of organelles at gastrocnemius muscle by 65%, in the lungs - in 4 times and in heart by 60-80% depending on the mitochondrial subpopulations; and appearance of young mitochondria and mitochondria with moderate degree of swelling, which favors the growth of the energy power of the mitochondrial apparatus of cells.