Effects of three cobra venoms on blood coagulation, platelet aggregation, and fibrinolysis

Abstract
The effects of the venoms ofNaja melanoleuca, Naja nigricollis, andOphiophagus hannahon blood coagulation, platelet aggregation, and fibrinolysis were studiedin vitro.All three venoms were shown to be anticoagulant. This action appeared to be due to an effect on both the extrinsic and blood thromboplastin mechanisms. Platelet aggregation in Chandler's tubes and adenosine diphosphate reactivity were inhibited by the three venoms, although in the case ofOphiophagus hannahvenom they were inhibited only with intermediate concentrations. The three venoms possessed proteolytic properties, but when incorporated into purified caseinolytic systems and euglobulin clot lysis systems inhibition of plasmin activity was observed.