Liver mitochondrial respiratory plasticity and oxygen uptake evoked by cobalt chloride in rats with low and high resistance to extreme hypobaric hypoxia.

High-altitude intolerance and consequently high-altitude sickness, is difficult to predict. Liver is an essential organ in glucose and lipid metabolism, and may play key role in the adaptation to high altitude. In response to extreme high altitude, mitochondrial respiration exhibits changes in substrate metabolism, mitochondrial electron transport chain activity, and respiratory coupling. We determined the cobalt chloride (CoCl 2 ) effects on liver mitochondrial plasticity and oxygen uptake in rats with low resistance (LR) and high resistance (HR) to extreme hypobaric hypoxia. The polarographic method proposed by Chance and Williams was used as a simple and effective tool to trace mitochondrial functionality and oxygen consumption. HR rats had more efficient processes of NADH- and FAD-generated mitochondrial oxidation. CoCl 2 promoted more efficient NADH-generated and diminished less efficient FAD-generated mitochondrial respiratory reactions in HR rats. CoCl 2 diminished both aerobic and anaerobic processes in LR rats. Glutamate and pyruvate substrates of NADH-generated mitochondrial pathways were highly affected by CoCl 2 . Red blood cells acted as cobalt depots in HR and LR rats. We have unveiled several mechanisms leading to differentiated mitochondrial respiratory responses to hypobaric hypoxia in LR and HR rats. Our study strongly supports the existence of adaptive liver mitochondrial plasticity to extreme hypoxia.