Effects of Ramipril on Proliferation of the Pulmonary Vascular Smooth Muscle Cells and PulmonaryVascular Remodeling Induced by Monocrotaline in Rats

Objective To investigate the therapeutic effect of ramipril on proliferation of the pulmonary vascular smooth muscle cells and pulmonary vascular remodeling induced by MCT in rats.Methods Thirty SD rats were randomly divided into three groups:control group,MCT group and MCT+ Ramipril group.The rats in the latter two groups were injected 60 mg/kg of MCT subcutaneously and then received Ramipril in drink water for 4 weeks.The rats in control group were injected saline subcutaneously first and then received normal drink water.Right ventricular systolic pressure(RVSP)was measured.The animals' hearts were measured to calculate the ratio of right ventricle to left ventricle plus septum(RV/LV+S,right ventricle mass to body weight(RV/BW)and left ventricle plus septum mass to body weight(LV+S/BW).Percentage of wall thickness(WT%)and percentage of wall area(WA%)of pulmonary arterioles were evaluated.Immunohistochemical stains were used to identifyα-actin and proliferation cells nuclear antibody(PCNA)distribution in pulmonary arteries.Restults After four weeks,these parameters of RVSP,RV/(LV+S),RV/BW,(LV+S)/BW,WT % and WA %,the positive ratio of PCNA in MCT group were significantly increased compared with control group.However,the above parameters were dramatically decreased in MCT+ Ramipril group.Compared with control group,α-actin IOD was lower in MCT group,while it was dramatically increased in MCT+ Ramipril group.Conclusion Ramipril can prevent the development of pulmonary arterial hypertension induced by MCT and inhibit pulmonary vascular remodeling by inhibiting the proliferation of pulmonary vascular smooth muscle cells.