[Differences in the hormonal status of rats highly and poorly resistant to hypoxia]

Rats were tested for hypobaric hypoxia and decapitated two weeks later at 9-12, 13-14 and 15-17 o'clock. The levels of corticosterone, insulin and testosterone were determined in serum by RIA. Great daily fluctuations and higher elevation of corticosterone level in response to additional 1.5-min hypoxia were observed in low hypoxia-resistant (HHR) rats. The correlation of corticosterone/insulin ratio was directly proportional in LHR rats and inversely proportional in HHR rats. No difference in testosterone and insulin levels in LHR and HHR rats was found.