[Effect of adrenomedullin 1-50 on chronic hypoxic pulmonary hypertension in rats]

Objective: To explore the effect of Adrenomedullin(1-50) (ADM(1-50)) on hypoxic pulmonary hypertension and pulmonary vascular structural remodeling and the plasma concentration of nitric oxide (NO) and hydrogen sulfide (H(2)S) in rats.

Methods: Twenty male Wistar rats were randomly divided into control group (n=7), hypoxic group (n=6) and hypoxic with ADM(1-50) group (n=7). ADM(1-50) was subcutaneously administered into rats of hypoxic with ADM(1-50) group by mini-osmotic pump (300 ng/h). After two weeks' hypoxic challenge, mean pulmonary arterial pressure (mPAP) was evaluated by using a right cardiac catheterization procedure. The ratio of right ventricular mass to left ventricular plus septal mass [RV/(LV+S)] was detected. Pulmonary vascular microstructure was measured and the ultrastructural changes in intra-acinar pulmonary arteries were observed. Meanwhile, plasma concentrations of NO and H(2)S were measured.

Results: mPAP was significantly increased in hypoxic rats than that in controls [(24.9+/-6.8) mmHg vs (14.3+/-2.4) mmHg, P<0.01,1 mmHg=0.133 kPa]; RV/(LV+S) was also significantly increased in hypoxic rats than that in controls [(0.318+/-0.054) vs (0.182+/-0.007), P<0.01]. Microstructure and ultrastructure of pulmonary arteries changed obviously in hypoxic rats with the development of hypoxic pulmonary vascular structural remodeling. Meanwhile, plasma NO and H(2)S concentrations in hypoxic rats were markedly decreased compared with controls. However, mPAP was significantly decreased in hypoxic rats treated with ADM(1-50) than that in hypoxic rats [(14.9+/-3.0) mmHg vs (24.9+/-6.8) mmHg, P<0.01]; RV/(LV+S) was also significantly decreased than that in hypoxic rats [(0.185+/-0.011) vs (0.318+/-0.054), P<0.01]. ADM(1-50) ameliorated pulmonary vascular structural remodeling of hypoxic rats in association with an increase in plasma NO and H(2)S concentrations.

Conclusion: ADM(1-50) plays an important role in regulation of the development of hypoxic pulmonary hypertension and hypoxic pulmonary vascular structural remodeling, through promoting NO and H(2)S production in hypoxic rats.