Maternal and umbilical venous levels of endothelin in women with pre-eclampsia.

Endothelin is a recently discovered, potent vasoconstrictive peptide. To investigate its involvement in pre-eclampsia, we measured its concentration in the plasma of 10 healthy non-pregnant women, 19 healthy pregnant women in early pregnancy, 26 healthy pregnant women in the third trimester, 18 women with pre-eclampsia in the third trimester and 6 women with pre-eclampsia in the postpartum period. In addition, the concentration of endothelin in umbilical venous plasma was measured in 7 healthy pregnant women and in 4 with pre-eclampsia. A sandwich-enzyme immunoassay for endothelin-1[1-21] was used. The plasma concentration of endothelin in pre-eclampsia significantly exceeded that of the healthy pregnant women during the third trimester. In pre-eclampsia this elevated level of plasma endothelin normalised with the fall in blood pressure 7 days postpartum. The level of endothelin in the umbilical vein was 6 to 8 times higher than that in the cubital vein both in the healthy pregnant women and in those with pre-eclampsia, but there was no significant difference in the umbilical venous plasma concentration of endothelin between those two groups. These observations suggest that the synthesis of endothelin may be increased in pre-eclampsia and that this increase may play a role in the elevation of peripheral vascular resistance and the production of peripheral ischaemic damage. Damage to the endothelial cells may then stimulate the synthesis of endothelin to initiate a vicious cycle.