IN-VIVO PLATELET ACTIVATION-INDUCED BY BOTHROPS-JARARACA VENOM IN RABBITS

Disturbances of platelet morphology, coagulation and fibrinolysis were studied 3, 6, and 24 h following administration of Bothrops jararaca snake venom to rabbits (80 mug/kg, i.v.). The activation of coagulatio n and fibrinolytic systems was demonstrated by a significant decrease in fibrinogen concentration, and an increase in fibrin(ogen) degradati on product concentration, respectively. However, the prothrombin activ ity remained within normal limits throughout. Significant thrombocytop enia was observed 3 h following venom administration. A decrease in pl atelet dense body numbers was observed until 24 h. 'Exhausted' platele ts and evidence of granular secretion were frequently observed in enve nomed rabbits. The open canalicular system was only dilated in extensi vely degranulated platelets. The mean platelet area and boundary value s were not significantly different from control group. Therefore, B. j araraca venom can stimulate platelets in vivo, inducing release of pla telet granular content. The etiology of thrombocytopenia in B. jararac a envenoming seems to be a multifactorial process, causing platelet se questration.