The Actions of Prostaglandins and the Interactions of Angiotensin II in the Isolated Perfused Human Placental Cotyledon

Abstract

Several lines of evidence suggest that in the fetal-placental circulation, the vasoconstrictive actions of angiotensin II may be modulated by prostaglandins. Firstly, prostaglandins have been shown to be vasoactive within the fetal-placental vaculature (Tulenko 1981; Mak et al., 1984). Secondly, angiotensin II is able to stimulate the release of PGE and prostacyclin (PGI₂) (a potent vasodilator) into the fetal circulation of the isolated perfused human placental cotyledon (Glance et al., 1985). Thirdly, in pathological pregnancies where umbilical blood flow is reduced (such as pre-eclampsia [Makila et al., 1983]), circulating fetal angiotensin II levels are increased (Broughton Pipkin and Symonds, 1977) and PGI₂ levels are decreased (Makila et al., 1983) when compared with levels found in normal pregnancies.