[Effects of high altitude on changes in blood coagulation in rats during prolonged administration of noradrenaline].

Alterations of the plasma factors of hemocoagulation produced by injection of norepinephrine (NE) at progressively increasing doses over 14 days (the total dose ran 35 mg/kg of body mass) were studied in three groups of rats, i.e., animals bred at the low altitude of 760 m in Bishkek (group I), animals in-adapted (group II) and adapted to high altitude of the Tuya-Ashu pass (3200 m, Group III). By the 7th day of NE injection group-I developed a moderate hypercoagulation which persisted till the end of experiment. In adapted animals the high altitude exposure initiated hypocoagulation shifts which then gave place to hypercoagulation ones due to elevated activity of the procoagulant component of homeostasis. Maximally pronounced hypercoagulation charges were recorded in in-adapted rats (group II) and interpreted as a stress-reaction to natural hypoxia augmented by the stress-agent (NE). High altitude revealed greater defense-adaptive potential of the homeostatic system manifested as enhancement of the anticoagulation blood activity, e.g., increased ability to inactivate thromboplastin and thrombin, and fibrinolysis.