[Enzymatic markers of cell membranes in rats during adaptation to hypoxic hypoxia].

The activities of Na+, K(+)-ATPase and 5'-nucleotidase of the plasma membranes, Ca++, Mg(++)-ATPase of the sarcoplasmic reticulum, mitochondrial cytochrome C-oxidase and succinate dehydrogenase were investigated in the brain, liver and gastrocnemius muscle of Wistar rats at various terms of adaptation to hypoxic hypobaric intermittent hypoxia. An increase in the activity of Na+, K(+)-ATPase and mitochondrial enzymes (mostly in the liver) as well as in the activity of Ca++, Mg(++)-ATPase in the skeletal muscle beginning from 14 days of adaptation have been shown. Starting with the same term the authors have registered the less marked changes of the enzymic markers of cell membranes in adapted rats under additional acute and severe hypoxic test when compared to unadapted animals. Possible changes in the regulation of membrane-bound enzyme activity during the process of adaptation to hypoxic hypoxia have been discussed.