5 展望 ADP受体结合实验及噻恩并吡啶药理研究资料都显示，在血小板表面可能有两种ADP受体。分子生物学研究也证实了P2X1与P2Y1两种嘌呤受体基因在血小板和巨核细胞的转录与表达。人们已可确定，血小板两种ADP受体有着各自的功能与作用机制。P2X1受体激活时促进钙离子的内流并抑制腺苷酸环化酶活性；P2Y1受体的激活与G蛋白偶联，通过磷脂酰肌醇的水解引起胞内贮存Ca2+的增加和血小板聚集［12］。这两种ADP受体都是血小板活化必不可少的。任何一种受体的缺陷都导致血小板不能活化，血小板的正常功能必须有两种受体的共同参与［13］。血小板ADP受体有独特的性质，ADP是其剌激剂，ATP是竞争性抑制剂；而在其它细胞上ADP和ATP对嘌呤类受体都表现相同的作用。血小板ADP受体类型、结构与功能的最后确定还有待于对先天性血小板ADP受体缺陷患者的基因研究以及对实验动物的血小板ADP受体基因敲除（knock out）的研究结果。血小板ADP受体的确定对于止血与血栓的病理生理研究具有重要的意义。最近有人发现，ADP受体参与了肝素引起的血小板减少性紫癜的发病过程［14］。此外，噻氯匹定已是最常用的一种抗血小板药物，其类似物clopidogrel也进入三期临床试用阶段。一些ADP受体拮抗剂在动物实验也表现出显著的抗血栓效果，有望成为新的抗血栓药物。这将进一步促进抗血小板药物的发展。
作者单位：王兆钺(215006 苏州医学院附属第一医院、江苏省血液研究所)
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