Adelman B, Michelson A D, Loscalzo J, Greenberg J, Handin R I
Blood. 1985 Jan;65(1):32-40.
We have studied the effect of streptokinase on platelets in platelet-rich plasma (PRP) and of plasmin on washed platelets. By three and one-half minutes after the addition of 50,000 IU/mL streptokinase to PRP, the maximum rate of ristocetin-induced platelet agglutination declined 40%, and by 60 minutes, it declined 70%. During the same time interval, the thrombin time increased from 20 seconds to over 120 seconds. At a concentration as low as 50 IU/mL, streptokinase reduced the maximum rate of ristocetin-induced platelet agglutination by 50% and prolonged the thrombin time to 1.5 times control value. Streptokinase added to PRP also caused inhibition of platelet aggregation following stimulation by 2.9 mumol/L adenosine diphosphate, 0.25 U/mL thrombin, and 0.025 mg/mL collagen. Plasmin, 0.05 to 1.0 CU/mL, reduced ristocetin-mediated agglutination of washed platelets in the presence of von Willebrand factor (vWF) from 66% of control to 2% of control, following a one-hour incubation. Autoradiograms produced following sodium dodecyl-polyacrylamide gel electrophoresis (SDS-PAGE) of plasmin-treated 125I-surface-labeled platelets demonstrated progressive loss of a protein with a molecular weight (mol wt) of 180,000; simultaneously, a protein with mol wt 135,000 appeared on autoradiograms produced following SDS-PAGE of the surrounding platelet medium. These proteins are similar in molecular weight to glycoprotein (gp) Ib, a platelet surface receptor for vWF, and glycocalicin, a proteolytic fragment of gpIb. By use of an enzyme-linked immunosorbent assay (ELISA) based immunoinhibition assay for glycocalicin, we were able to demonstrate that plasmin treatment of washed platelets released a glycocalicin-related antigen into the surrounding medium and that appearance of this material corresponding to loss of vWF-dependent, ristocetin-induced agglutination.
我们研究了链激酶对富含血小板血浆（PRP）中血小板的作用以及纤溶酶对洗涤后血小板的作用。向PRP中加入50,000 IU/mL链激酶后3分半钟，瑞斯托霉素诱导的血小板凝集最大速率下降了40%，到60分钟时，下降了70%。在相同的时间间隔内，凝血酶时间从20秒增加到超过120秒。链激酶浓度低至50 IU/mL时，可使瑞斯托霉素诱导的血小板凝集最大速率降低50%，并使凝血酶时间延长至对照值的1.5倍。添加到PRP中的链激酶还可抑制2.9 μmol/L二磷酸腺苷、0.25 U/mL凝血酶和0.025 mg/mL胶原刺激后的血小板聚集。0.05至1.0 CU/mL的纤溶酶在孵育1小时后，在存在血管性血友病因子（vWF）的情况下，可使洗涤后血小板的瑞斯托霉素介导的凝集从对照的66%降至对照的2%。用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）对经纤溶酶处理的125I表面标记血小板进行放射自显影，结果显示分子量（mol wt）为180,000的一种蛋白质逐渐丢失；同时，在周围血小板培养基的SDS-PAGE后的放射自显影上出现了分子量为135,000的一种蛋白质。这些蛋白质的分子量与糖蛋白（gp）Ib（vWF的血小板表面受体）和糖甘蛋白（gpIb的蛋白水解片段）相似。通过使用基于酶联免疫吸附测定（ELISA）的糖甘蛋白免疫抑制测定法，我们能够证明纤溶酶处理洗涤后的血小板会将一种与糖甘蛋白相关的抗原释放到周围培养基中，并且这种物质的出现与vWF依赖的、瑞斯托霉素诱导的凝集的丧失相对应。
