Prostaglandin production and stimulation by angiotensin II in the isolated perfused human placental cotyledon

Levels of prostaglandins E and F_2α, thromboxane B₂, and 6-oxo-prostaglandin F_1α were measured by radioimmunoassay in the maternal and fetal effluents of isolated human placental cotyledons perfused in vitro. All prostaglandins measured were released in greater amounts by the maternal side than by the fetal side of the perfused cotyledon although there were no consistent concentration gradients between the two sides. The approximate rank order of prostaglandin release into the maternal side was thromboxane B₂ > prostaglandin F_2α {reversed tilde equals} prostaglandin E {reversed tilde equals}- 6-oxo-prostaglandin F_1α, and that into the fetal side was thromboxane B₂ {reversed tilde equals} prostaglandin F_2α {reversed tilde equals} prostaglandin E {reversed tilde equals} 6-oxo-prostaglandin F_1α. Injection of angiotensin II (0.5 μg) into the fetal circulation stimulated prostaglandin E and 6-oxo-prostaglandin F_1α but not thromboxane B₂ and prostaglandin F_2α release into the fetal circulation and had no effect on maternal release. Angiotensin II (0.5 μg) had no effect on either side of the perfused cotyledon when injected into the maternal circulation. It is proposed that prostaglandin release into both maternal and fetal circulations may be flow-dependent and that the angiotensin II-stimulated release of prostaglandin E and 6-oxo-prostaglandin F_1α may serve to modulate the vasoactive actions of angiotensin II on the fetal vasculature.