COMPARISON OF THE ACTIONS OF U‐46619, A PROSTAGLANDIN H2‐ANALOGUE, WITH THOSE OF PROSTAGLANDIN H2 AND THROMBOXANE A2 ON SOME ISOLATED SMOOTH MUSCLE PREPARATIONS

Abstract

The actions of the prostaglandin H 2 (PGH 2) analogue, U‐46619, have been compared with those of PGH 2 and thromboxane A 2 (TxA 2) on a range of isolated smooth muscle preparations in a superfusion cascade system. U‐46619 was a potent agonist on guinea‐pig lung strip, dog saphenous vein and rat and rabbit aortae. In contrast, U‐46619 was weak or inactive on guinea‐pig ileum and fundic strip, cat trachea and dog and cat iris sphincter muscles, preparations on which either PGE 2 or PGF 2α was the most potent agonist studied. PGH 2 was active on all of the preparations and displayed little selectivity. On some of the preparations, the actions of PGH 2 may have been mediated indirectly by conversion to other prostanoids. In contrast, TxA 2 displayed the same pattern of selectivity as U‐46619, being a potent agonist on the lung strip and vascular preparations but weak or inactive on the others. It is suggested that U‐46619 is a selective TxA 2‐mimetic and that it should therefore be a valuable tool in the study of the actions of TxA 2