Effects of vasoactive autacoids on different segments of human umbilicoplacental vessels.

Effects of serotonin, prostaglandin E2, prostaglandin F2 alpha, U 46619 (a thromboxane A2 mimetic) and angiotensin I and II on the perfusion pressure were studied on vessel segments from human umbilical arteries, placental arteries and the umbilical vein during in vitro perfusions. All drugs were found to induce vasoconstriction. Serotonin displayed strong vasoconstrictor potencies in all vessel segments, whereas the responsiveness to the other autacoids differed greatly in the various segments. In the umbilical artery prostanoids were most potent in the juxtafetal segment, whereas angiotensin I and II displayed greatest effects in the juxtaplacental segment. The results lend additional support to the concept that angiotensins and prostanoids are of importance in the regulation of fetal extracorporeal blood flow.