The effect of sildenafil on nitric oxide content and nitric oxide synthase activity in chronic hypoxic pulmonary hypertension in rats

Objective To investigate the effect of sildenafil on nitric oxide content and nitric oxide synthase activity in chronic hypoxic pulmonary hypertension in rats.Methods Thirty male Wistar rats were randomly divided into 3 groups of 6 each:control group,hypoxic group and sildenafil treated group.The animal model of pulmonary hypertension was established by exposing the rats to hypoxic conditions of ordinary pressure for 6 weeks.The mean pulmonary artery pressure(mPAP) was examined by right cardiac catheterization,the right ventricle(RV) and left ventricle plus septum (LV+S)of rats were weighed respectively and the RV/(LV+S) was calculated,NO and NOS activity in serum and lung tissue were measured via spectrophotometer,Lung specimens were examined by light microscope in HE staining.Results In hypoxic group,mPAP,RV,RV/(LV+S) were increased significantly and NO and NOS activity in serum and lung tissue were markedly decreased compared with those of control group(all P0.01),In sildenafil treated group,mPAP,RV,RV/(LV+S) were decreased significantly and NO and NOS activity in serum and lung tissue were increased significantly compared with those of hypoxic group(P0.01 or P0.05).Conclusions Sildenafil could prevent pulmonary hypertension from forming through increasing concentration of NO and NOS activity and inhibiting pulmonary arterial remodeling.