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Identification of D/sub 1/-like dopamine receptors on human blood platelets

Journal Article · · Life Sci.; (United States)

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 the authors report that membranes from human blood platelets possess high affinity, saturable and stereoselective binding sites for the D/sub 1/ dopamine receptor antagonist (/sup 3/H)SCH 23390. (/sup 3/H)SCH 23390 appeared to label a single class of binding sites with a B/sub max/ of 18.6 +- 1.6 fmolmg protein and a K/sub D/ of 0.8 nM. The potencies of different dopaminergic antagonists and agonists in displacing (/sup 3/H)SCH 23390 from blood platelet membranes were similar to those obtained for striatal membranes. Unlike the classically defined D/sub 1/ receptors, e.g. those in striatum, the D/sub 1/ receptor sites on platelets appeared no to be coupled to the adenylate cyclase system, hence the term D/sub 1/-like. The D/sub 1/ 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 D/sub 1/-like receptors

Research Organization:
Vrije Universiteit Brussel (Belgium)
OSTI ID:
5298834
Journal Information:
Life Sci.; (United States), Journal Name: Life Sci.; (United States) Vol. 42:18; ISSN LIFSA
Country of Publication:
United States
Language:
English