Amniotic fluid prostacyclin and thromboxane in normal, preeclamptic, and some other complicated pregnancies.

To study the involvement of the antiaggregatory and vasodilator prostacyclin (PGI2) and proaggregatory and vasoconstrictor thromboxane A2 (TxA2) in complicated pregnancies, we measured by radioimmunoassay the stable metabolites of PGI2 and TxA2, 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and thromboxane B2 (TxB2), respectively, in samples of amniotic fluid collected at amniocentesis from 88 women between 30 and 40 weeks' normal or complicated pregnancy. The concentrations (mean +/- SE) of 6-keto-PGF1 alpha were 171.8 +/- 9.0 pg/ml in normal pregnancies (N = 27), 134.4 +/- 9.3 pg/ml in severe preeclampsia (N = 13) (0.001 less than p less than 0.005 in comparison with normal pregnancy), 175.6 +/- 13.9 pg/ml in mild preeclampsia (N = 14) (0.01 less than p less than 0.05 in comparison with severe preeclampsia), 168.5 +/- 16.9 pg/ml in diabetic pregnancies (N = 14), 158.7 +/- 5.9 pg/ml in rhesus-immunized pregnancies (N = 10), and 178.7 +/- 13.7 pg/ml in pregnancies with intrauterine fetal growth retardation (N = 10). The corresponding TxB2 concentrations were, respectively, 35.0 +/- 5.7 pg/ml, 29.1 +/- 4.6 pg/ml, 31.3 +/- 3.1 pg/ml, 35.3 +/- 4.0 pg/ml, 31.4 +/- 5.9 pg/ml, and 39.2 +/- 3.2 pg/ml, and these levels did not differ from each other. The level of 6-keto-PGF1 alpha in amniotic fluid correlated with the pregnancy week in normal and preeclamptic pregnancies, and the levels of TxB2 in amniotic fluid in normal, preeclamptic, and rhesus-immunized pregnancies. Furthermore, these two prostanoids correlated with each other in normal pregnancy and in all complications except rhesus-immunized pregnancies. Thus, it is evident that the release of PGI2 into the amniotic fluid is decreased in severe preeclampsia.