PLACENTAL PRODUCTION OF NITRIC-OXIDE AND ENDOTHELIN IN NORMAL AND PREECLAMPTIC PREGNANCIES

Objective: To examine the production rates of nitric oxide (NO) and en dothelin in normal and preeclamptic placentas. We hypothesized that if placental production of NO is decreased and/or that of endothelin is increased in preeclampsia, these compounds could contribute to the pat hophysiology of placental vasoconstriction. Methods: Human placental t issues were obtained from women with normal pregnancies (n = 8) and wo men with preeclampsia (n = 6). Tissues (350 mg) were incubated in DMEM for 48 h. Main Outcome Measures: Incubation samples were analyzed for NO by nitrite and endothelin by RIA of endothelin 1-21. Results: Both normal and preeclamptic placentas produced NO and endothelin progress ively during the 48 h of incubation. The concentrations after 48 h for nitrite were 29 +/- 8 nmol/mg protein for normal placentas and 34 +/- 11 nmol/mg protein for preeclamptic placentas. For endothelin, the co ncentrations after 48 h were 20 +/- 3 fmol/mg and 23 +/- 3 fmol/mg, re spectively. There were no statistically significant differences for ei ther NO or endothelin between normal and preeclamptic placentas, P > 0 .5. Conclusion: Whole placental villi produce NO and endothelin, and s o these compounds are probably involved in the normal regulation of pl acental blood flow. However, there are no differences in the productio n rates between normal and preeclamptic placentas. Our data do not sup port a role for NO and endothelin in the pathophysiology of preeclamps ia.