The actions of prostaglandins and their interactions with angiotensin II in the isolated perfused human placental cotyledon

Abstract

Summary. The prostaglandins PGE 1 , PGE 2 , PGD 2 , PGF 2α ., U46619 and 6 β ‐PGI l were administered as bolus injections both separately and in combination with angiotensin II into the fetal circulation of isolated human placental cotyledons perfused in vitro . PGF 2α , and PGD 2 , caused small dosedependent increases in fetal perfusion pressure when compared with U46619 which acted as an extremely potent vasoconstrictor of the fetal‐placental vasculature. PGE 1 , caused very small dose‐dependent decreases in fetal perfusion pressure when injected on its own. In combination with angiotensin 11, PGE 1 , PGD 2 , and 6 β ‐PG1 1 , caused significant, dose‐related attenuations of the angiotensin II vasoconstrictive response whereas PGE 2 , PGF 2α , and U46619 potentiated the response. Injections of angiotensin II after the infusion of indomethacin into the fetal circulation resulted in a potentiation of angiotensin II induced vasoconstriction. The results indicate that prostaglandins exert their effects on the fetal‐placental circulation by modulating the actions of angiotensin II.