Plasma nitric oxide metabolite levels are decreased in pre-eclamptic women complicated with fetal distress

To investigate the possible role of impairment of the maternal vascular nitric oxide (NO)-soluble guanylate cyclase system in the maintenance of placental oxygen supply to the fetus in pre-eclampsia, maternal plasma levels of nitric oxide metabolites (nitrate and nitrite, i.e. NOx), atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), and guanosine 3′,5′-cyclic phosphate (cGMP) were measured using Griess reagent, specific immunoradiometric assays (IRMA) and specific radioimmunoassay (RIA), respectively. The subjects were ten normal non-pregnant women, and 91 normal pregnant women, nine pre-eclamptic women without fetal distress and six pre-eclamptic women with fetal distress. In the pre-eclamptic women with fetal distress, plasma NOx levels were significantly (p < 0.05) lower than those in gestational age-matched normotensive pregnant women, but not in those without fetal distress. Plasma ANP and BNP levels in the pre-eclamptic pregnant women with fetal distress were significantly higher than those in gestational age-matched normotensive pregnant women. No significant differences were observed among plasma levels of cGMP, the common second messenger of both soluble and particulate guanylate cyclases. The present findings suggest that endothelial NO synthase (eNOS) is impaired in women whose pregnancies are complicated with pre-eclampsia and fetal distress.