[Influence of preliminary adaptation to altitude hypoxia on catecholamine concentration in the hypothalamus, adrenals and heart under great physical stress].

Rats were subjected to adaptation to heigth hypoxia in an altitude chamber at the "heigth" 6 km within 7 weeks for 6 hrs a day. Concentration of noradrenaline and adrenaline was normal in hypothalamus; in myocardium content of noradrenaline was also normal but content of adrenaline was slightly decreased; in adrenal glands content of both hormones was distinctly increased. High physical activity (7 hrs swimming) did not alter content of noradrenaline in hypothalamus and adrenal glands of unadaptated rats but decreased 3-fold the content in myocardium. In adaptated rats, by contrast, such loading caused distinct decrease in content of noradrenaline in hypothalamus and adrenal glands and did not affect the content of adrenaline and noradrenaline in myocardium. Thus, adaptation to the heigth hypoxia prevented completely the decrease of catecholamines content in myocardium under loading and simultaneously increased the extent of mobilization of noradrenaline stores in hypothalamus and adrenal glands.