Studies on the Expression of Heme Oxygenase-1 of Placenta and the Level of Plasma Endogenous Carbon Monoxide in Patients with Pregnancy Induced Hypertension

Objective: To evaluate the role of HO-CO system in the pathophisiological changes of PIH. Methods We examined the expression of HO in placenta and plasma level of CO in 61 patients with PIH and 20 normal late pregnant women by immunohistochemstry and Chalmers's Dithionate. Results:① HO-1 protein was present predominantly in syncytiotrophoblastic cells and some stem villous endothelium. The intensity of HO-1 immunostaining in syncytiotrophoblast and vascular endothelium was significantly reduced in PIH group when compared with the normal controls, especially in moderate and severe PIH groups. There was negative correlation between the intensity of HO-1 immunostaining and the extent of PIH.② Compared with normal women, plasma CO level in PIH group decreased with advanced degree of PIH, especially in moderate and severe PIH groups. ③ Of four groups, there was a significant positive correlation between level of plasma CO and expression of placental HO-1.Conclusions: CO that produced by placental HO-1 may be the main source of plasma CO. HO-CO system may be one of the factors in the pathogenesis of PIH.