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

Levels of prostaglandins E and F2 alpha, thromboxane B2, and 6-oxo-prostaglandin F1 alpha 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 greater than prostaglandin F2 alpha congruent to prostaglandin E congruent to 6-oxo-prostaglandin F1 alpha, and that into the fetal side was thromboxane B2 congruent to prostaglandin F2 alpha congruent to prostaglandin E congruent to 6-oxo-prostaglandin F1 alpha. Injection of angiotensin II (0.5 microgram) into the fetal circulation stimulated prostaglandin E and 6-oxo-prostaglandin F1 alpha but not thromboxane B2 and prostaglandin F2 alpha release into the fetal circulation and had no effect on maternal release. Angiotensin II (0.5 microgram) 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 F1 alpha may serve to modulate the vasoactive actions of angiotensin II on the fetal vasculature.