Roles of the protein kinases on platelet functions

我们研究了蛋白激酶在血小板聚集和释放中的作用。&lt；方法&gt；1.血小板：从健康志愿者的血液中制备富含血小板的血浆和洗涤的血小板。2.血小板反应的测定：使用CAF-100Ca^lt；2&gt；分析仪监测血小板聚集和ATP释放。通过荧光素-荧光素酶反应检测ATP释放。结果1.肌球蛋白轻链激酶的作用。肌球蛋白轻链激酶的特异性抑制剂Wortmannin抑制ADP诱导的血小板聚集，但不影响其形状变化。2.蛋白激酶C的作用。蛋白激酶C的特异性抑制剂PKC-I对U46619诱导的血小板聚集和ATP的释放影响不大。然而，GRGDS抑制血小板聚集可阻止在PKC-I存在的情况下ATP的释放。另一方面，洗涤后的血小板在PKC-I存在的情况下不能看到ATP的释放。结论1.提示肌球蛋白轻链激酶的激活是ADP诱导的血小板聚集的先决条件，而不是其形状改变的先决条件。2.提示人血小板释放ATP存在蛋白激酶C依赖和非依赖的机制，后者的激活可能依赖于聚集和血浆因子。

We examined the roles of the protein kinases in platelet aggregation and release.<Methods>1.Platelets : Platelet rich plasma and washed platelets were prepared from bloods of healthy volunteers.2.Measurement of platelet responses : Platelet aggregation and ATP release were monitored using a CAF-100 Ca^<2+> analyzer. ATP release was measured by the luciferin-luciferase reaction.<Results>1.The roles of myosin light chain kinase.The specific inhibitor of myosin light chain kinase wortmannin inhibited ADP-induced platelet aggregation with no effect on their shape change.2.The roles of protein kinase C.The specific inhibitor of protein kinase C PKC-I did not affect much U46619-induced platelet aggregation and ATP release. However the inhibition of platelet aggregation with GRGDS prevented ATP release in the presence of PKC-I.On the other hand, ATP release was not seen in the presence of PKC-I in washed platelets.<Conclusion>1.It was suggested that myosin light chain kinase activation is a prerequisite for ADP-induced platelet aggregation, but not for changes in their shape.2.It was suggested that there are protein-kinase C-dependent and -independent mechanisms for ATP release by human platelets and that activation of the latter mechanism may depend on aggregation and plasma factors.