The effect of type 1 diabetes mellitus on vascular responses to endothelin-1 in pregnant women

Diabetes is associated with vascular dysfunction, which may be due in part to altered vascular responses to endogenous peptides such as endothelin-1. These altered responses may also contribute to the decreased maternal perip heral resistance in pregnancy. The aim of this study was to examine the eff ect of diabetes on the vasoconstrictor response to endothelin-1 in pregnant women. Small arteries were isolated from nine healthy pregnant, seven type 1 diabe tic pregnant women, and five healthy nonpregnant women. Contraction curves were performed on a wire myograph for noradrenaline (1 nM to 30 muM) and en dothelin-1 (1 pM to 0.3 muM). Maximum responses and sensitivity were compar ed by t test. No differences in maximum response to noradrenaline or potassium were seen among the three groups. The maximum response to endothelin-1 was significan tly increased in pregnancy (P < 0.05), whereas endothelin-1 sensitivity was reduced in the diabetic compared with the nondiabetic pregnant women (P < 0.05). Pregnant women have an increased maximum vasoconstriction response to endot helin-1 compared with nonpregnant women, whereas diabetic pregnant women de monstrate reduced sensitivity to endothelin-1. These observations suggest t hat endothelin-1 may play a role in maintaining peripheral vascular tone in normal pregnancy, and the decreased sensitivity seen in pregnant women wit h diabetes may reflect abnormal vascular reactivity.