Savi P, Beauverger P, Labouret C, Delfaud M, Salel V, Kaghad M, Herbert J M
Haemobiology Research Department, Sanofi Recherche, Toulouse, France.
FEBS Lett. 1998 Feb 6;422(3):291-5. doi: 10.1016/s0014-5793(98)00025-8.
ADP acts as an agonist of platelet aggregation via specific receptors which are still to be characterised. Amplification by PCR of a human platelet cDNA library confirmed the presence of mRNA of the P2Y1 receptor in platelets. In order to determine if these P2Y1 receptors were involved in ADP-induced platelet activation, we determined the effects of A3P5PS, an antagonist of the P2Y1 receptor, on the binding of [33P]2-MeS-ADP, a potent analogue of ADP. We found that A3P5PS displaced about 27% of [33P]2-MeS-ADP binding, a receptor population which has been shown to be resistant to treatment with clopidogrel, a selective anti-ADP agent. A3P5PS specifically inhibited 2-MeS-ADP-induced shape change and calcium increase but did not affect adenylyl cyclase down-regulation. 2-MeS-ADP-induced platelet aggregation was also inhibited by A3P5PS but was restored when platelets were further activated by serotonin, a non-aggregating compound, therefore suggesting that P2Y1-mediated stimulation is an absolute prerequisite for ADP to induce platelet aggregation and a key event for platelet activation and aggregation to occur. These results therefore show that ADP-induced aggregation cannot be attributed to activation of P2Y1 alone, but must be attributed to the simultaneous activation of the high affinity receptor (P2Y1) and a low affinity receptor of ADP (still to be discovered), each of them essential, but neither able to trigger aggregation alone.
ADP通过仍有待确定特征的特定受体，作为血小板聚集的激动剂。对人血小板cDNA文库进行PCR扩增，证实血小板中存在P2Y1受体的mRNA。为了确定这些P2Y1受体是否参与ADP诱导的血小板活化，我们测定了P2Y1受体拮抗剂A3P5PS对[33P]2-甲基硫代ADP（一种强效ADP类似物）结合的影响。我们发现A3P5PS取代了约27%的[33P]2-甲基硫代ADP结合，这一受体群体已被证明对选择性抗ADP药物氯吡格雷的治疗具有抗性。A3P5PS特异性抑制2-甲基硫代ADP诱导的形态变化和钙增加，但不影响腺苷酸环化酶的下调。A3P5PS也抑制2-甲基硫代ADP诱导的血小板聚集，但当血小板被5-羟色胺（一种非聚集性化合物）进一步激活时，聚集得以恢复，因此表明P2Y1介导的刺激是ADP诱导血小板聚集的绝对先决条件，也是血小板活化和聚集发生的关键事件。因此，这些结果表明，ADP诱导的聚集不能仅归因于P2Y1的激活，而必须归因于高亲和力受体（P2Y1）和ADP低亲和力受体（仍有待发现）的同时激活，它们各自都是必不可少的，但单独任何一个都不能触发聚集。
