[Carnosine in adaptation to hypobaric hypoxia].

Adaptation to hypobaric hypoxia causes increases in the carnosine content in rat liver mitochondria. Model experiments showed that carnosine added to isolated rat liver mitochondria increases the rate of ADP-stimulated respiration with alpha-ketoglutarate (but not with succinate) as well as the intensity (ADP/t) and efficiency (ADP/O) of oxidative phosphorylation--by 56%, 49%, and 15%, respectively. Increases in the intensity and efficiency of oxidative phosphorylation (by 100% and 30%, respectively) were also observed in liver mitochondria isolated from rats adapted to hypobaric hypoxia. Activation of ADP-stimulated respiration was found after addition of glutamate plus malate and pyruvate plus glutamate to liver mitochondria. This stimulating effect was coupled to aminotransferase activation and was abolished by the transaminase inhibitor aminooxyacetate. Carnosine addition to mitochondria or its accumulation in mitochondria under hypoxia is associated with activation of alpha-ketoglutarate oxidation and its formation through transamination.