title: Adenosine 5-diphosphate antagonists and human platelets: no evidence that aggregation and inhibition of stimulated adenylate cyclase are mediated by different receptors.
abstract: 1 Adenosine 5'-diphosphate (ADP) induces human platelet aggregation and noncompetitively inhibits stimulated human platelet adenylate cyclase; it has been suggested that these two effects are mediated by separate ADP receptors on the platelet surface. 2 Adenosine 5'-triphosphate and seven adenine nucleotide analogues were tested as inhibitors of both effects of ADP on human platelets, and were found to be competitive. 3 pA2 values were calculated for each antagonist for inhibition of both effects of ADP, and a good correlation (correlation coefficient 0.87; p less than 0.01) was found between the pA2 values for inhibition of ADP-induced aggregation and the pA2 values for inhibition of the effect of ADP on stimulated adenylate cyclase. 4 Such a correlation does not support the suggestion that ADP-induced aggregation and the inhibition by ADP of stimulated adenylate cyclase are mediated by two separate receptors.
mesh_terms: D000244:Adenosine Diphosphate / Q000037:antagonists & inhibitors*; D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000097:blood; D000527:Alprostadil; D001792:Blood Platelets / Q000187:drug effects* / Q000201:enzymology; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D010974:Platelet Aggregation / Q000187:drug effects; D011458:Prostaglandins E / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011983:Receptors, Purinergic
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D011458:Prostaglandins E; D011956:Receptors, Cell Surface; D011983:Receptors, Purinergic; D000244:Adenosine Diphosphate; D000262:Adenylyl Cyclases; D000527:Alprostadil