PROTEIN-C ACTIVATOR FROM THE VENOM OF AGKISTRODON-BLOMHOFFI-USSURIENSIS RETARDS THROMBUS FORMATION IN THE ARTERIOVENOUS SHUNT IN RATS

Protein C (PC) is an anticoagulant protein which, being activated by t hrombin, degrades factors V/Va and VIII/VIIIa and releases a tissue-ty pe plasminogen activator. Some Agkistrodon snake venoms contain PC act ivators which, in experiments, exert an anticoagulant action. An antit hrombotic effect of the PC activator from the venom of A. blomhoffi us suriensis on the model of thrombus formation in the arterio-venous shu nt in rats was under investigation. Administration of the PC activator resulted in a dose-dependent prolongation of the thrombus formation t ime and a decrease in plasma PC activity, which were accompanied by a decrease in factor V activity and APTT prolongation. No reliable chang es in the t-PA level, ADP- and epinephrine-induced platelet aggregatio n were observed. Platelet adhesion to glass beads diminished. We assum e that the antithrombotic effect of the PC activator from the A. blomh offi venom in the platelet-dependent thrombosis model is caused by PC activation and subsequent factor V inactivation as well as by platelet adhesiveness reduction.