钙离子通道A23187对血小板聚集和蛋白质磷酸化的影响

Effects of A23187 on Platelet Aggregation and Protein Phosphorylation

以３２ＰＮａ２ＨＰＯ４标记猪血小板，在阿斯匹林阻断花生四烯酸代谢，Ａｐｙｒａｓｅ去除分泌的ＡＤＰ情况下，以Ａ２３１８７和ＰＭＡ为血小板激动剂，ｓｔａｕｒｏｓｐｏｒｉｎｅ为ＰＫＣ抑制剂，研究Ｃａ２＋和蛋白激酶Ｃ在血小板聚集中的作用．结果表明，ａＡ２３１８７在１～２０μｍｏｌ／Ｌ引起血小板聚集，相应地，明显地引起４０ｋｕ、２０ｋｕ蛋白质磷酸化，且存在剂量和时间效应关系．ｂＡ２３１８７和ＰＭＡ在血小板聚集和蛋白质磷酸化上都存在着协同效应．ｃ１μｍｏｌ／Ｌｓｔａｕｒｏｓｐｏｒｉｎｅ可大部分抑制２０μｍｏｌ／ＬＡ２３１８７诱导的血小板聚集和２０ｋｕ、４０ｋｕ蛋白质磷酸化．结果提示，Ｃａ２＋激活血小板是建立在激活ＰＫＣ的基础上，Ｃａ２＋通过激活ＰＫＣ诱导血小板聚集，这是Ｃａ２＋激活血小板的主要途径．

To study further the role of Ca^2+ and protein kinase C in platelet aggregation, suspensions of aspirintreated, 32Pprelabled, washed pig platelets containing ADP scavenger in the buffer were stimulated by Ca^2+ ionophore A23187 and PMA,a stimulator of protein kinase C. The results indicated that: (1) 1～20 μmol/L A23187 induced platelet aggregation,as well as the phosphorylation of 40 ku and 20 ku proteins.There were doserespone and timerespone effects of the protein phosphorylation in A23187induced platelet activation. (2) A23187 and PMA were synergistic in platelet aggregation and protein phosphorylation. (3)Stauroporine, a protein kinase C inhibitor, in concentration of 1 μmol/L,largely suppressed platelet aggregation and completely suppressed phosphorylation of 40 ku and 20 ku proteins induced by 20 μmol/L A23187. The results imply that Ca^2+ mobilization alone could activate protein kinase C in platelet, and Ca^2+induced platelet aggregation is largely dependent on activation of protein kinase C.