Interaction of prostaglandin D2 with prostacyclin, carbacyclin and the hydantoin prostaglandin, BW245C, in guinea-pig platelets

Abstract

The anti-aggregating actions of prostaglandin D2 (PGD2) have been compared to prostacyclin (PGI2), its stable analogue carbacyclin and a hydantoin prostaglandin, BW245C, in guinea-pig PGI2, carbacyclin and BW245C were potent inhibitors of ADP-induced aggregation in guinea-pig platelets, with ID50 values comparable to those obtained in human platelet-rich-plasma. In contrast, PGD2 acted as a weak and partial inhibitor in guinea-pig platelet aggregation, producing a bell-shaped dose-response relationship. PGD2 induced a dose-related antagonism of the inhibitory actions of BW245C, prostacyclin and carbacyclin on guinea-pig platelets. However, PGD2 did not antagonize the inhibitory actions of either forskolin or dibutyryl cyclic AMP on this platelet preparation. The results suggest a non-specific interaction of PGD2 with these prostanoid binding sites on guinea-pig platelets.