Plasma and placental nitric oxide levels in women with and without pre-eclampsia living at different altitudes

Objective: To investigate the nitric oxide (NO) levels in the plasma and the placentas of pregnant women with pre-eclampsia and women without pre-eclampsia, and to determine the effect of high or low altitude of residence. Methods: NO was determined by chemoluminescence and group comparisons were performed. Results: Women with pre-eclampsia (n = 63) had higher plasma NO levels (38.6 ± 17.44 vs 30.6 ± 12.44 μmol/L, P = 0.004) and higher placental NO levels (38.5 ± 17.0 vs 24.3 ± 7.16 ng/mg protein, P < 0.05) compared with women without pre-eclampsia. A similar trend was found when comparisons were made according to altitude of residence. NO levels were significantly higher in the plasma of pre-eclamptic women living at sea level (41.11 ±18.78 vs 28.96 ± 9.57 μmol/L, P = 0.003), and in the placentas of women living at high altitude (39.51 ± 16.98 vs 21.91 ± 6.64 ng/mg protein, P < 0.0001). Conclusion: Women with pre-eclampsia had higher plasma and placental NO levels and the differences were associated with altitude of residence.