[Ultrastructural aspects of cross adaptation to cold and altitude hypoxia]

Prolonged cold and altitude exposures were examined for their impact on the ultrastructure of the albino rat diaphragm and liver. The ultrastructural analysis of the respiratory muscle and liver showed their structural response differences under these conditions. There was a substantial rise in mitochondrial and lipid droplet volume densities and maintenance of glycogen stores in the muscle fibers at the end of the experiment. The hepatocyte mitochondrial responses were similar, but less pronounced and slower. The glycogen and plastic reserves of hepatocytes were reduced. This provides evidence for that the adaptive process is less effective in the hepatocytes than in the muscle under these conditions. At the same time the lack of structural disturbances in the muscle fibers and hepatocytes during prolonged altitude and cold exposures may be considered as the evidence of the stabilizing influence of the latter factor, its protective role in the cross-adaptation mechanisms.