The relationship between constitutive nitric oxide synthase (cNOS) and pregnancy induced hypertension.

To study the relationship between constitutive nitric oxide synthase (cNOS) and pregnancy induced hypertension (PIH), cNOS expression and localization in placental villi of PIH patients (n = 15) and normal pregnancy patients (n = 15) were immunohistochemically studied. The positive immunostaining of cNOS was located in trophocytes and cytoplasm of vascular endothelial cells. The positive rate in PIH patients was much higher than that in cases of normal pregnancy. The positive rates were 34.40% in mild, 44.74% in middle and 50.14% in severe PIH patients respectively. There was a significant difference in positive rate among the mild, middle and severe PIH patients (P < 0.01). It is concluded that the increase of cNOS activity probably was the results of protective or compensatory mechanism of PIH course.