Abstract: | The release of prostaglandin E2 and F2α, thromboxane B2 and 6-keto-prostaglandin F1α was measured in isolated human placental cotyledons perfused under high- and low-oxygen conditions. Also the effect of reoxygenation on prostaglandin production was studied. During the high-oxygen period, prostaglandin E2 accounted for 44 % and 6-keto-prostaglandin F1α for 28 % of all prostaglandin release, and the rank order of prostaglandin release was E2 > 6-keto-prostaglandin F1α > thromboxane B2 > prostaglandin F2α. Hypoxia had no significant effect on quantitative prostaglandin release, but the ration of prostaglandin E2 to prostaglandin F2α was significantly increased. After the hypoxic period during reoxygenation the release of 6-keto-prostaglandin F1α was significantly decreased, as was the ratio of 6-keto-prostaglandin F1α to thromboxane B2. Also the ratio of the vasodilating prostaglandins (E2, 6-keto-prostaglandin F1α) to the vasocontricting prostaglandins (thromboxane B2, prostaglandin F2α) was decreased during reoxygenation period. With the constant flow rate, the perfusion pressure increased during hypoxia in six and was unchanged in three preparation. The results indicate that changes in the tissue oxygenation in the placenta affect prostaglandin release in the fetal placental circulation. This may also have circulatory consequences. |