Abstract: Objective To explore the regulating effect of intermedin (IMD) on the pulmonary vascular structural remodeling and pulmonary hypertension induced by high pulmonary blood flow in rats and its mechanism. Methods Twenty-one male SD rats were randomly divided into control group (n=7), shunt group (n=8) and shunt with IMD group (n=6) . Abdominal aorta and inferior vena cava shunting was produced in rats of the latter two groups. After 8 weeks, IMD [1.5 μg/(kg?h)] was administered into rats of shunt with IMD group subcutaneously by mini-osmotic pump for 2 weeks. Mean pulmonary artery pressure (mPAP) and the ratio of right ventricular mass to left ventricular plus septal mass [RV/(LV+SP)] was evaluated. The pulmonary vascular micro-morphologic changes of rats were observed. The content of NO in the serum and lung tissue homogenate was detected by nitric acid enzyme reduction method. The expression of eNOS protein in the lung tissue was detected by Western blotting analysis. Result Compared with those of control group, mPAP, RV/(LV+SP), the muscularization of small pulmonary vessels and relative medial thickness of pulmonary artery in rats of shunt group were all significantly increased. Meanwhile, the content of NO in the serum and pulmonary tissue homogenate and the expression of eNOS protein in rats of shunt group were all significantly decreased compared with those of control group. However, IMD significantly decreased the mPAP and RV/(LV+SP), alleviated the changes of pulmonary vascular micro-structure, with the elevation of the content of NO in the serum and pulmonary tissue homogenate and the expression of pulmonary eNOS protein in shunting rats. Conclusion IMD alleviates the development of pulmonary hypertension and pulmonary vascular structural remodeling induced by high pulmonary blood flow, through eNOS/NO path way.

Key words: pulmonary hypertension, high pulmonary blood flow, intermedin, nitric oxide