DIRECT ANTAGONISM OF THE TXA2 BLOOD PLATELET RECEPTOR

我们以前报道了一个合成和药理活性的 一系列直接抑制人血小板的新化合物 血栓素A2/前列腺素H2（TXA2/PGH2）受体。 结果发现 这些试剂，特别是13-氮杂前列腺烷酸（13-APA）2， 拮抗TXA_2/PGH_2诱导的血小板活化， 对其他生理激动剂诱导的血小板活化的影响。 在 目前的建议，研究已经设计，现在使用这些代理人 作为研究潜在机制的选择性药理学工具 与TXA2/PGH2诱导的血小板活化有关。 具体地说， 实验提出进行结合研究，使用（3H）13-APA在 完整血小板和血小板膜制品。 这些研究应 提供第一个直接证据，证明存在和位置， 血小板TXA2/PGH2受体。 为了识别和表征 这种假定受体的蛋白质组成，放射性标记的烷化剂 将使用13-APA的衍生物。 此外，实验 建议更清楚地建立TXA2和PGH2的相对能力， 引起血小板活化。 通过使用竞争性受体 结合试验在这个建议和选择性TXA2合成酶 抑制剂，应该有可能确定PGH2是否是 自身能够与血小板受体相互作用。 最后我们将 探讨直接TXA2/PGH2受体拮抗剂单独或 联合前列环素可以作为一种有效的手段， 降低体内血小板反应性。 除上述研究外， 将进行综合规划，以开发新药剂， 在进一步表征TXA2/PGH2的参与方面具有重要价值 血小板活化 该计划将涉及新的合成 化合物，以研究与 TXA2/PGH2受体，以及合成修饰的 13-azaprostanoid（用于亲和层析）以纯化受体 绝佳的价钱 因此，这一建议的广度从分子水平延伸到了分子水平。 TXA_2与其受体的相互作用在 血栓素A2拮抗剂在体内抑制血小板活化。 这 为今后的发展提供更合理的基础。 用于治疗血栓栓塞性疾病的药物。

We previously reported the synthesis and pharmacological activity of a series of new compounds which directly inhibit the human blood platelet thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptor. It was found that these agents, in particular 13-azaprostanoic acid (13-APA)2, specifically antagonize platelet activation induced by TXA2/PGH2, with virtually no effects on platelet activation induced by other physiological agonists. In the present proposal, studies have been designed to now employ these agents as selective pharmacological tools to investigate the underlying mechanism associated with TXA2/PGH2-induced platelet activation. Specifically, experiments are proposed to perform binding studies using (3H) 13-APA in intact platelets and platelet membrane preparations. These studies should provide the first direct evidence for the existence and location of a platelet TXA2/PGH2 receptor. In order to identify and characterize the protein composition of this presumed receptor, a radiolabeled alkylating derivative of 13-APA will be employed. In addition, experiments are proposed to more clearly establish the relative ability of TXA2 and PGH2 to cause platelet activation. Through the use of a competitive receptor binding assay developed in this proposal and selective TXA2 synthetase inhibitors, it should be possible to establish whether or not PGH2 is itself capable of interacting with a platelet receptor. Finally, we will explore the possibility that direct TXA2/PGH2 receptor antagonism alone or in combination with prostacyclin may serve as an effective means of reducing platelet reactivity in vivo. In addition to the above studies a synthetic program will be undertaken to develop new agents which should be of substantial value in further characterizing the involvement of TXA2/PGH2 in platelet activation. This program will involve the synthesis of new compounds to investigate the structural requirements for interaction with the TXA2/PGH2 receptor, as well as the synthesis of a modified 13-azaprostanoid (for affinity chromatography) to purify the receptor site. The breadth of this proposal therefore extends from the molecular interaction of TXA2 with its receptor to the application of TXA2-antagonists to the inhibition of platelet activation in vivo. This approach should provide a more rational basis for the future development of pharmacological agents useful in the treatment of thromboembolic disorders.