Nitric oxide in different types of hypertension during pregnancy

Abstract

1. Serum nitric oxide (NO) levels (determined by its products of oxidation) were assessed in nonpregnant women, normal pregnant women and patients suffering from mild pre-eclampsia (MPE), severe pre-eclampsia (SPE), chronic hypertension (CHT) and CHT with pre-eclampsia (CHT+PE). The levels of NO products were significantly reduced during pregnancy in MPE (P < 0.001), CHT+PE (P < 0.01) and SPE (P < 0.05). Significant reductions of NO products were also observed in puerperium (P < 0.001) in all groups except CHT+PE (Pc0.05). 2. In normal pregnancy, three events were related to NO levels: (1) negative correlations were found between the levels of nitrite (r = -0.73, P = 0.0003), nitrate (r = -0.53, P = 0.017) and the number of weeks of gestation; (2) in the caesarean section group, the levels of NO at puerperium were significantly lower (P < 0.05) than those during pregnancy; and (3) there was a significant reduction in NO levels in the pregnant women carrying male fetuses as compared with female fetuses (Px0.05). 3. In SPE, the patients with a family history of hypertension had lower levels of NO compared with the patients without such a history (P<0.05). 4. A negative correlation was observed between systolic blood pressure, diastolic blood pressure and NO levels in MPE (r = -0.62, P = 0.013 and r = -0.68, P = 0.0049 respectively) and SPE (r = -0.72, P = 0.004 and r = -0.53, P = 0.037 respectively). 5. In SPE, positive correlations were observed between platelet count and nitrite (r = 0.67, P= 0.006) and nitrate levels (r = 0.56, P = 0.028). 6. In MPE, patients with anti-hypertensive treatment showed significantly (P < 0.05) higher levels of NO compared with the non-treated patients. 7. NO may be important in the physiopathology of hypertension during pregnancy, although several factors may affect its levels.