Potential role of endothelin-1 in normal and hypertensive pregnancies.

Endothelins are the most potent naturally occurring vasoconstrictors yet discovered. Both normal and abnormal pregnancies are associated with significant changes in vascular smooth muscle; therefore the potential role of endothelin in pregnancy was investigated. Plasma immunoreactive endothelin-1 concentration was measured by radioimmunoassay in blood from women with normal pregnancy and preeclampsia and in cord blood from normal pregnancies. Endothelin-1 levels were elevated in pregnant women during labor when compared with levels in nonpregnant women and patients with normal pregnancies before labor. Preeclampsia in nonlaboring women before treatment was associated with higher endothelin values when compared with values in normal nonlaboring patients and women with preeclampsia after magnesium sulfate infusion. The umbilical venous concentration of endothelin was 10 times higher than normal pregnant levels and four times higher than levels in laboring patients.