ALTERATIONS OF INTRAUTERINE EICOSANOID PRODUCTION IN PREGNANCY-INDUCED HYPERTENSION - DECREASED PRODUCTION OF 12-HYDROXYEICOSATETRAENOIC ACID IN THE PLACENTA

The important role of eicosanoids in pregnancy-induced hypertension is generally accepted. Because of the lack of innervation of the utero-p lacental vessels, humoral vasoactive factors are important for the reg ulation of vascular tone. Until now, mainly the balance of vasodilatat ive and vasoconstrictive prostaglandins has been studied. We were able to confirm their intrauterine imbalance in hypertensive pregnancies. In addition, the placental production of less known lipoxygenase metab olites has been analyzed in this study. Intrauterine tissues (30-100mg wet weight) were examined for their release of eicosanoids. Short ter m tissue cultures were performed in Hanks balanced salts solution (HBS S) at 37 degrees C in an atmosphere of 95% air/5% CO2 with and without incorporation of tritiated arachidonic acid. The arachidonate metabol ites in culture media were analyzed by High Performance Liquid Chromat ography (HPLC) with radioactivity detection or by enzymeimmunoassays o r radioimmunoassays, respectively. All intrauterine tissues released m ore lipoxygenase metabolites than cyclooxygenase metabolites with 12-h ydroxyeicosatetraenic acid (12-HETE) as their main merabolite. The pla cental release of 12-HETE was significantly decreased in hypertensive pregnancies. In hypertensive pregnancies the ratio TXB(2)/6-keto-PGF(1 alpha) synthesis was increased. Lipoxygenase metabolites, especially 12-HETE, seem to have important physiological and pathophysiological f unctions in the intrauterine compartment. Their biological role in thi s context needs further investigation.