title: Differential inhibition by adenosine or by prostaglandin E1 of human platelet aggregation induced by adenosine 5'-O-(1-thiodiphosphate) and adenosine 5'-O-(2-thiodiphosphate).
abstract: Adenosine 5'-diphosphate (ADP) induces human platelet aggregation and inhibits stimulated adenylate cyclase. Adenosine 5'-O-(1-thiodiphosphate) (ADP-alpha-S) and adenosine 5'-O-(2-thiodiphosphate) (ADP-beta-S) act at the ADP receptor and achieve the same maximal rate of human platelet aggregation as each other. Adenosine and prostaglandin E1, which noncompetitively inhibit ADP-induced aggregation by stimulating adenylate cyclase, inhibit aggregation induced by ADP-x-S more than aggregation induced by ADP-beta-S. ADP-x-S, unlike ADP-beta-S and ADP itself, does not inhibit stimulated adenylate cyclase. This suggests that the inhibition of stimulated adenylate cyclase by ADP, although not a cause of aggregation, may be of physiological importance in reducing the effects of endogenous agents such as adenosine and prostaglandins (for example, prostacyclin) to which the platelet may be exposed.
mesh_terms: D000244:Adenosine Diphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000527:Alprostadil; D006801:Humans; D066298:In Vitro Techniques; D010974:Platelet Aggregation / Q000187:drug effects*; D011458:Prostaglandins E / Q000494:pharmacology*; D013873:Thionucleotides / Q000494:pharmacology*
chemical_list: D011458:Prostaglandins E; D013873:Thionucleotides; C030812:adenosine 5'-O-(2-thiodiphosphate); C018444:adenosine 5'-O-(1-thiodiphosphate); D000244:Adenosine Diphosphate; D000527:Alprostadil