Characterization of the responses to serotonin and prostanoids in human umbilical arteries perfused in vitro

In order to characterize the action of some vasoactive autacoids on the umbilical artery, pressure responses of serotonin, PGE2, PGF2 alpha and U46619 (a thromboxane A2 mimetic) have been investigated during in vitro perfusion. Serotonin, PGE2 and PGF2 alpha caused biphasic responses in which both the dilator and the constrictor phases were found to be dose-dependent. Indomethacin or SQ 29.548 (a thromboxane A2 receptor antagonist) did not affect the response to serotonin, whereas indomethacin reduced or abolished the vasodilator and vasoconstrictor action of PGE2 and PGF2 alpha. U46619 induced monophasic pressor responses which were abolished by SQ 29.548. The results indicate that PGE2 and PGF2 alpha, but not serotonin, interfere with the local production of vasoactive prostanoids. The altered synthetic activity modify the responses to PGE2 and PGF2 alpha in the umbilical artery.