PLASMA ENDOTHELIN IN NORMAL AND DIABETIC PREGNANCY

OBJECTIVE - To examine endothelin-1 (ET-1) concentrations longitudinal ly throughout pregnancy in healthy and insulin-dependent diabetic wome n and to evaluate the relationship between ET-1 and big ET-1 in normal pregnancy. RESEARCH DESIGN AND METHODS - Venous blood samples were ob tained consecutively in gestational weeks 18, 28, and 38 from 40 healt hy women with uneventful pregnancies and 24 pregnant women with IDDM. By radioimmunoassay, plasma ET-1 and big ET-1 were analyzed in the hea lthy women and plasma ET-1 in the diabetic women. RESULTS - In the dia betic pregnant women, plasma ET-1 levels were significantly higher tha n in healthy pregnant women during the entire observation period (P < 0.001), but did not change with advancing gestational age. Five of the diabetic, but none of the healthy pregnant women, developed preeclamp sia. ET-1 levels did not differ between the diabetic women who develop ed preeclampsia and those who did not. Plasma ET-1 levels in healthy p regnant women were within the range of those in healthy nonpregnant wo men and did not change during pregnancy. The big ET-1 levels increased and the ET-1/big ET-1 ratio decreased significantly during the observ ation period. CONCLUSIONS - Plasma ET-1 levels do not change with adva ncing gestational length. During normal pregnancy, the ET-1/big ET-1 r atio decrease, indicating a suppressed converting enzyme activity or a ltered clearance of ET-1. Pregnant women with IDDM have markedly eleva ted ET-1 levels. Although diabetic women with and without preeclampsia did not differ with respect to endothelial dysfunction, as reflected by elevated ET-1 concentration, we cannot exclude that altered endothe lial function may be of importance for the increased frequency of pree clampsia in pregnant IDDM patients.