[The role of heparin and tissue-type plasminogen activator in the adaptation of the hemostatic system to high altitude].

The role of endogenous heparin and tissue-type plasminogen activator in the middle-period (25 days) adaptation of haemostasis to high altitude (altitude 3200 m) and formation or "high-altitude hypocoagulation" was studied in the experiments on white rats. It was observed that the formation of "high-altitude hypocoagulation" is connected with an increase of heparin and tissue-type plasminogen activator level due to its release from must and endothelial cells to the bloodstream. Histochemical analysis showed that at the course of adaptation to high altitude the increase in blood heparin level was caused by the stimulation of must cells secretory activity. The endothelium of lung vessels is the main source of tissue-type plasminogen activator release into the blood. The existence of interconnection between the changes in haemostasis and stimulation of angiogenesis at high altitude is proposed.