The effect of cobra venom factor on hemostasis in guinea pigs.

Recent investigations have indicated an association between the coagulation and complement systems. Our present studies, designed to explore this association further, demonstrated that a purified anticomplementary fraction of cobra venom, cobra venom factor (CVF), produced significant changes in hemostasis when injected into guinea pigs. Some of the effects described may be secondary to the transient intravascular hemolysis produced by CVF. However, a more direct effect of purified CVF on platelet function is suggested by increased platelet factor 3 activity and inhibition of clot retraction and lysis. Furthermore, injection of purified CVF produced striking elevation of plasma fibrinogen without detectable fibrin or fibrinogen degradation products, altered plasminogen levels, and significantly reduced the activities of several extrinsic and intrinsic coagulation factors. These observations provide additional data to support the concept of a functional relationship between the mechanisms that initiate coagulation and activate complement.