Haemorrhagic mechanisms of some snake venoms in relation to protection by estriol succinate of blood vessel damage

The vascular haemorrhagic action of cobra venom depends on the presence of a heparin precipitable material, the latter being possibly the so called Direct Lytic Factor, which apparently renders the phospholipase of the venom capable of causing bleeding. The haemorrhagic action of Agkistrodon piscivorus venom is independent of a heparin precipitable factor and it is also unlikely that the phospholipase activity of the venom is responsible for the haemorrhages. Estriol succinate counteracts the bleedings caused by cobra venom, but not the haemorrhages produced by the snake venom lacking the heparin precipitable factor.