Hypoxia tolerance in rats in relation to tissue glycogen levels.

Previous work has shown that rats on high fat (52%) diet (HFD) were hypoxia-resistant compared to rats on carbohydrate (75% CHO) diet (HCD) and on normal diet (ND), as evidenced from their greatly increased survival time on exposure to 10,668 m simulated altitude. Determination of glycogen levels in the heart, skeletal muscle, liver, lungs, and kidneys show that, in hypoxia-susceptible rats, tissue glycogen was decreased in ND and was unchanged in HCD rats. In HFD rats, glycogen in tissues greatly increased on altitude exposure. It is postulated that hypoxia tolerance of HFD rats was enhanced due to: (i) preconditioning to gluconeogenesis and (ii) systemic acidosis caused by their increased fat ingestion.