Abstract: Objective To study the effects of repeated hypoxic exposures (HEs) on glycolysis, mitochondrial oxidative phosphorylation and energy charge in the mouse brain. Methods Adult Balb/c mice were repeatedly exposed to hypoxia for 5 times and the standard tolerant time and body temperature were recorded. The activities of PFK, PK and mitochondrial complex I in the brain were assayed. Phosphoadenosines and energy charge were measured. Results Repeated HEs prolonged the hypoxic tolerance and reduced the body temperature. The activities of PFK and PK experienced regular changes, with an increase in 1st and 3rd HEs and a decline to control levels in 5th HE. The complex I activity continued to decrease during HEs. The energy charge was kept stable. Conclusion REs lead to a regular change in the activity of glycolysis, a continued inhibition of mitochondrial oxidative phosphorylation, and a maintained energy charge in the brains of mice.

Key words: hypoxia, phosphofructokinase, pyruvate kinase, complex I, energy charge