Subtypes of P2-purinoceptors. Studies using analogues of ATP

Studies using analogues of ATP have allowed a comparison of structure-activity relationships that has provided ample evidence for the existence of at least four subtypes of P2-purinoceptors responsive to adenine nucleotides. Competitive antagonists have defined clearly the P2T subtype, specific agonists are now available for the P2X and P2Y subtypes, and leads have been given for development of reversible specific antagonists for the P2X and P2Z subtypes. The availability especially of inhibitors of ectonucleotidases and of specific antagonists for each P2-purinoceptor subtype would enable the roles of endogenous extracellular nucleotides to be ascertained, as has already been shown for the interaction of platelets with the vasculature.