Adaptation to periodic hypoxia and hyperoxia improves resistance of membrane structures in heart, liver, and brain.

A novel principle of short-term periodic adaptive training by varying the oxygen level from hypo- to hyperoxia is substantiated both theoretically and experimentally. Short-term adaptation to hypoxia-normoxia produced a membrane-protective effect in the heart and cerebral cortex, but increased the sensitivity to free radical oxidation and decreased the level of components of the antioxidant defense system in the liver. Hypo-hyperoxia adaptation produced a membrane-stabilizing effect in the heart, brain, and liver, which was more pronounced compared to the effect of hypoxia-normoxia training. In contrast to hypoxia-normoxia adaptation, in case of hypo-hyperoxia training the adaptive defense developed as early as 15 days after the start of training.