Tissue Oxygenation and Mitochondrial Respiration under Different Modes of Intermittent Hypoxia

Serebrovskaya, Tatiana V., Valentyna I. Nosar, Larissa V. Bratus, Bronislav L. Gavenauskas, and Iryna M. Mankowska. Tissue oxygenation and mitochondrial respiration under different modes of intermittent hypoxia. High Alt Med Biol 14,280-288, 2013.We compared the results of five modes of intermittent hypoxia training (IHT) on gastrocnemius muscle Po-2 and heart and liver mitochondrial respiration in rats. Minutes of hypoxia, %O-2, and recovery minutes on air in each mode were: 1) 5, 12%, 5; 2) 15, 12%, 15; 3) 5, 12%, 15; 4) 5, 7%, 5; and 5) 5, 7%, 15. Mode 1 proved best in that Pmo(2) dropped minimally at the end of every hypoxic bout and recovered quickly after each bout. One, 2, and 3 week IHT in mode 1 each increased tissue PO2 in both normoxic and 30min severe hypoxic (7% O-2) tests. Adaptation to IHT in Mode 1 caused the substrate-dependent reorganization of liver and heart mitochondrial energy metabolism favoring NADH-dependent oxidation and improving the efficiency of oxidative phosphorylation. Mitochondrial adaptation occurred after 14 days of IHT in liver tissue, but after 21 days in myocardium, and was preserved during the 3 months following IHT termination. When using Mode 2, positive changes were also registered, but were less pronounced. Other IHT modes provoked negative effects on Pmo(2) levels, both during hypoxic periods and reoxygenation. In conclusion, the most effective IHT regimen is 5min 12% O-2 with 5min breaks, five cycles per day during 2 or 3 weeks depending on the task of IHT.