EFFECT OF MAGNESIUM-SULFATE ON PLASMA ENDOTHELIN-1 LEVELS IN NORMAL AND PREECLAMPTIC PREGNANCIES

OBJECTIVE: We attempted to determine the effects of magnesium sulfate on: (1) endothelin-1 concentration in preeclampsia, preterm labor, and term pregnancy and (2) endothelin-1 release from human umbilical cord endothelial cells. STUDY DESIGN: Plasma samples were prospectively collected from eight women with preeclampsia, six preterm labor patients, and eight term patients undergoing external cephalic version before and 2 hours after magnesium sulfate infusion. Supernatants were collected from human umbilical cord endothelial cells exposed to magnesium sulfate and controls. All samples were assayed with a specific radioimmunoassay for endothelin-1. Paired Student t test and analysis of variance were used for statistical analysis. RESULTS: Magnesium sulfate infusion in preeclampsia lowered endothelin-1 levels compared with preinfusion values (6.6 +/- 3.81 before and 4.75 +/- 2.28 after infusion, p < 0.02). Magnesium sulfate did not have an effect on endothelin-1 concentration in preterm and term pregnancies. Magnesium sulfate did not alter the endothelin-1 release from human umbilical cord endothelial cells. CONCLUSION: A significant reduction of endothelin-1 plasma levels after magnesium sulfate therapy is limited to preeclampsia. In contrast, this lowering effect was not exhibited in women without preeclampsia or in normal endothelial cells.