NITRIC-OXIDE CONCENTRATIONS ARE INCREASED IN THE FETOPLACENTAL CIRCULATION IN PREECLAMPSIA

OBJECTIVE: The aim of this study was to measure serum concentrations o f total nitrites, as an index of nitric oxide synthesis, in the matern al and fetal circulations of normal pregnancies and in pregnancies com plicated by preeclampsia. STUDY DESIGN: We studied 32 women with preec lampsia and 36 with uncomplicated pregnancies. Maternal venous blood s amples were collected from all of the patients, and umbilical venous b lood was collected from 13 of the preeclamptic group and 17 of the con trol group. Serum nitric oxide concentrations were determined with the Greiss reaction by measuring combined oxidation products of nitric ox ide, serum nitrite and nitrate after reduction with nitrate reductase. RESULTS: There were no significant differences in maternal serum nitr ite concentrations between the groups (control group 29.8 +/- 1.07 mu mol/L, preeclamptic group 29.5 +/- 1.06 mu mol/L). Significantly highe r serum nitrite concentrations were found in umbilical venous serum in the preeclamptic group compared with the control group (34.59 +/- 1.1 2 mu mol/L vs 23.90 +/- 1.05 mu mol/L, p < 0.01). CONCLUSIONS: Total n itrites are increased in the fetoplacental circulation in preeclampsia . These results support the hypothesis that increased nitric oxide pro duction may be a compensatory response to improve blood flow or may pl ay a role in limiting platelet adhesion and aggregation.