NITRIC-OXIDE IN DIFFERENT TYPES OF HYPERTENSION DURING PREGNANCY

1. Serum nitric oxide (NO) levels (determined by its products of oxida tion) were assessed in nonpregnant women, normal pregnant women and pa tients 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 reduct ions of NO products were also observed in puerperium (P<0.001) in all groups except CHT+PE (P<0.05). 2. In normal pregnancy, three events we re 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 gro up, the levels of NO at puerperium were significantly lower (P<0.05) t han those during pregnancy; and (3) there was a significant reduction in NO levels in the pregnant women carrying male fetuses as compared w ith female fetuses (P<0.05). 3. In SPE, the patients with a family his tory of hypertension had lower levels of NO compared with the patients without such a history (P<0.05). 4. A negative correlation was observ ed between systolic blood pressure, diastolic blood pressure and NO le vels 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, p ositive 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, pat ients with anti-hypertensive treatment showed significantly (P<0.05) h igher levels of NO compared with the non-treated patients. 7. NO may b e important in the physiopathology of hypertension during pregnancy, a lthough several factors may affect its levels.