[Effects of Vipera berus venom on the activity of some coagulation factors]

The activity of some clotting factors of human blood after incubation at 37 degrees C with Vipera berus venom (400 microgram/ml of plasma) has been measured. Factor V, initially, is activated by venom, but rapidly its activity decreases, becoming lower of that of controls and it exhausts oneself almost fully after 2 hours. Changes in the prothrombin and fibrinogen activity by venom action have not been noted.