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.