[Effects of hypoxia on the activity of the sympathetic-adrenal system].

Experiments on rat males (120-150 g b.weight) inhaling air with oxygen concentration 16, 14, 12, 10, 8 and 5.3% for an hour and placed at the altitudes 2000, 3500 and 3200 in above the sea level in the mountains demonstrated that adrenaline and noradrenaline concentrations in the brain tissues, adrenals, blood and urine depend on the intensity and duration of the exposure to low pO2 in the air.

Heart adrenoreactivity during acute haemic hypoxia.

The influence of acute haemic hypoxia of mild and moderate degree, produced by subcutaneous administration of sodium nitrite (25-30 or 50 mg/kg) supporting the blood haemoglobin production, on heart adrenoreactivity was studied in experimental rats. An intensified sympathoadrenal activity was detected, that manifested itself by a marked increase in adrenaline content in the hypothalamus, brain stem and heart. In analogous experiments performed in dogs, with increasing severity of hypoxia a decrease in arterial pressure and left ventricular pressure, increase in left ventricular end-diastolic pressure, and an impairment of myocardial contractile function were observed.

[Changes in neutral peptide hydrolase levels in the blood and catecholamine levels in the tissues during adaptation to high altitude hypoxia].

Activity of neutral peptide-hydrolases in blood plasma and content of catecholamines in the tissues of rats under conditions of their stay in mountains at different height have been studied in dynamics. Unidirectional phase changes in activity of proteolytic enzymes of blood plasma and content of catecholamines in adrenal glands are revealed. A conclusion is made on participation of neutral blood peptide-hydrolases in organism adapted to Alpine hypoxia.