De Keyser J, De Waele M, Convents A, Ebinger G, Vauquelin G
Department of Neurology, Akademisch Ziekenhuis, Vrije Universiteit Brussel, Belgium.
Life Sci. 1988;42(18):1797-806. doi: 10.1016/0024-3205(88)90047-1.
Dopamine is able to inhibit the epinephrine-induced aggregation of human blood platelets, but the mechanism of action has not been elucidated. In this study we report that membranes from human blood platelets possess high affinity, saturable and stereoselective binding sites for the D1 dopamine receptor antagonist (3H) SCH 23390. (3H) SCH 23390 appeared to label a single class of binding sites with a Bmax of 18.6 +/- 1.6 fmol/mg protein and a KD of 0.8 nM. The potencies of different dopaminergic antagonists and agonists in displacing (3H) SCH 23390 from blood platelet membranes were similar to those obtained for striatal membranes. Unlike the classically defined D1 receptors, e.g. those in striatum, the D1 receptor sites on platelets appeared not to be coupled to the adenylate cyclase system, hence the term "D1-like". The D1 agonist SKF 38393 was more potent than dopamine in inhibiting platelet aggregation induced by epinephrine, and the effects of dopamine and SKF 38393 were prevented by SCH 23390. These results suggest that the inhibitory action of dopamine on the epinephrine-induced platelet aggregation is mediated through these D1-like receptors.
多巴胺能够抑制肾上腺素诱导的人血小板聚集，但其作用机制尚未阐明。在本研究中，我们报告人血小板膜对D1多巴胺受体拮抗剂（3H）SCH 23390具有高亲和力、可饱和且立体选择性的结合位点。（3H）SCH 23390似乎标记了一类单一的结合位点，其Bmax为18.6±1.6 fmol/mg蛋白，KD为0.8 nM。不同多巴胺能拮抗剂和激动剂从血小板膜上置换（3H）SCH 23390的效力与从纹状体膜上获得的效力相似。与经典定义的D1受体（如纹状体中的那些受体）不同，血小板上的D1受体位点似乎未与腺苷酸环化酶系统偶联，因此称为“类D1”。D1激动剂SKF 38393在抑制肾上腺素诱导的血小板聚集方面比多巴胺更有效，并且多巴胺和SKF 38393的作用可被SCH 23390阻断。这些结果表明，多巴胺对肾上腺素诱导的血小板聚集的抑制作用是通过这些类D1受体介导的。
