AIMTo investigate the expression of hypoxia-inducible factor-1 alpha (HIF-1alpha) in rats with chronic pulmonary hypertension induced by hypoxia and hypercapnia and its relationship with nitric oxide(NO).

METHODSFourty male Sprague-Dawley rats were randomly divided into four groups, normal control group (NC), hypoxia-hypercapnia group (HH), hypoxia - hypercapnia + L-arginine liposome group(HP) and hypoxia-hypercapnia+ N-nitro-L-arginine methylester group (HM). Colorimetric analysis, immunohistochemistry and in situ hybridization were used for detection of NO, HIF-1alpha and constitutive nitric oxide synthase (ecNOS).

RESULTS(1) The mean pulmonary arterial pressure (mPAP) and the weight ratio of right ventricular to left ventricle plus septum (RV/(LV + S)) of HH group were higher than those of NC group (P < 0.05), HP group much lower than HH group (P < 0.01), mPAP of HM higher than HH group ( P < 0.05). 2)0 Contents of NO in plasma and pulmonary tissue homogenates of HH group were much lower than those of NC group (P < 0.01), HP group higher than HH group (P < 0.01). There were no difference between HM group and HH group. (Expression of HIF-1alpha and HIF-1alpha mRNA in pulmonary arterioles of HH group were significantly higher than those of NC group( P < 0.01), HP group lower than HH group (P < 0.01) ,HM group higher than HH group (P < 0.01); Whereas expression of ecNOS and ecNOS mRNA in pulmonary arterioles of HH were lower than those of NC group( P < 0.05, IP group higher than HH group (P < 0.01), HM group lower than HH group (P < 0.05).

CONCLUSIONHIF-1alpha is involved in the pathogenesis of chronic pulmonary hypertension induced by hypoxia and hypercapnia. The protective function of NO in the pathogenesis might be partly depended on its effects on the expression/activity of HIF-1alpha in lung.