蛋白激酶C在血小板聚集中的作用

Role of Protein Kinase C in Platelet Aggregation

利用￣（３２）Ｐ－ＮａＨ２ＰＯ４标记猪血小板，以蛋白激酶Ｃ的４０ｋＤ底物为蛋白激活的标志．用血小板激动剂在聚集浓度范围内处理血小板，结果表明，除了不能使猪血小板聚集的肾上腺素外，凝血酶等激动剂都使血小板４０ｋＤ底物蛋白磷酸化明显增加，同时３８ｋＤ，２６ｋＤ蛋白质磷酸化也明显增加，且４０ｋＤ底物磷酸化与血小板聚集有平行增加关系．蛋白激酶Ｃ在血小板聚集中可能起着重要的调节作用。

Suspensions of aspirin-treated,(32)P-prelabeled, pig washed platelets containing ADP scavengers in the buffer were activated with thrombin, PAF, ADP, collagen, epinephrine and PMA. Except epinephrine,an agonist did not induce pig platelet aggregation, other agonists in concentration of aggregation induced 40kD polypeptide phosphorylation. Phosphorylation of 20kD, 26kD,38kD polypeptide were also increased. The 47kD substrate of PKC reported in some other papers was not found in this experiment. The phosphorylation of the 40kD as a substrate of PKC was increased dose-dependently with increasing concentrations of PAF or PMA. Low concentration(10-500nM) of PMA induced after a slow. linearly proceeding aggregation(EC50=50nM, concen. giving halfmaximal aggregation). The phosphorylation of the 40kD polypeptide induced by PMA was increased dependently with time. The results suggested that platelet aggregation occurred in parallel with PKC activation,and that PKC is the important regulator of platelet aggregation.