Speijer H, Govers-Riemslag J W, Zwaal R F, Rosing J
Department of Biochemistry, University of Limburg, Maastricht, The Netherlands.
Thromb Haemost. 1987 Jun 3;57(3):349-55.
Purified snake venom prothrombin activators were used to probe the procoagulant properties of platelet membranes. Human platelets were able to stimulate prothrombin activation by the venom activators from Oxyuranus scutellatus and Notechis scutatus, while the prothrombin activator from Echis carinatus was not affected by the presence of platelets. The prothrombin-converting activity of platelets was further studied with the venom activator from Oxyuranus scutellatus and with the factor Xa-Va complex as prothrombin activating enzymes. Stimulation of platelets with collagen, collagen plus thrombin or with the Ca-ionophore A23187 resulted in a considerable increase of platelet prothrombin converting activity probed with the factor Xa-Va complex as well as with the prothrombin activator from Oxyuranus scutellatus. The stimulatory effect of activated platelets on the rates of prothrombin activation by Oxyuranus scutellatus was similar to that determined for factor Xa-Va-catalyzed prothrombin activation. Compared to non-stimulated platelets, platelets stimulated with thrombin plus collagen exposed 20-times more procoagulant sites for as well the factor Xa-Va complex, as for the venom activator from Oxyuranus scutellatus. The actual number of procoagulant sites per platelet determined with the factor Xa-Va complex was in close agreement with the number of sites determined with the venom activator. Also the time course of appearance of procoagulant activity during platelet stimulation by collagen plus thrombin was comparable for both activator complexes. Phospholipase A2 treatment of stimulated platelets resulted in an almost complete loss of their ability to stimulate prothrombin activation by the enzyme from Oxyuranus scutellatus or by factor Xa-Va complex.(ABSTRACT TRUNCATED AT 250 WORDS)
纯化的蛇毒凝血酶原激活剂被用于探究血小板膜的促凝血特性。人血小板能够刺激来自盾尖吻蛇和虎蛇的毒液激活剂激活凝血酶原，而锯鳞蝰的凝血酶原激活剂不受血小板存在的影响。使用盾尖吻蛇的毒液激活剂以及因子Xa - Va复合物作为凝血酶原激活酶，进一步研究了血小板的凝血酶原转化活性。用胶原蛋白、胶原蛋白加凝血酶或钙离子载体A23187刺激血小板，会导致用因子Xa - Va复合物以及盾尖吻蛇的凝血酶原激活剂检测的血小板凝血酶原转化活性显著增加。活化血小板对盾尖吻蛇激活凝血酶原速率的刺激作用与因子Xa - Va催化凝血酶原激活所测定的作用相似。与未刺激的血小板相比，用凝血酶加胶原蛋白刺激的血小板对因子Xa - Va复合物以及盾尖吻蛇的毒液激活剂暴露的促凝位点多20倍。用因子Xa - Va复合物测定的每个血小板促凝位点的实际数量与用毒液激活剂测定的位点数量密切一致。在胶原蛋白加凝血酶刺激血小板过程中，两种激活剂复合物促凝活性出现的时间进程也具有可比性。用磷脂酶A2处理受刺激的血小板，会导致它们几乎完全丧失刺激盾尖吻蛇的酶或因子Xa - Va复合物激活凝血酶原的能力。（摘要截短于250字）
