Objective To investigate the protective effects of sildenafil treatment on histopathologic changes seen in hyperoxia induced lung injury.Methods Eighty term neonatal Sprague-Dawley(SD) rats were randomly assigned into four group:air-exposed control group,air-exposed+sildenafil-treated group,hyperoxia-exposed control group,and hyperoxia-exposed+sildenafil-treated group.The air control group was exposed to air(FiO2=0.21).The hyperoxia-exposed groups were continuously exposed to hyperoxia(FiO2=0.85).The sildenafil-treated group received sildenafil(100 mg·kg-1) subcutaneously everyday.On the 14th day postnatal,radical alveolar counts(RAC),microvessel count were performed,and lung morphology was studied.Their lungs were examined for immunohistochemical staining of endothelial nitric oxide synthase(eNOS).Results Treatment of hyperoxia-exposed rats with sildenafil resulted in a significant increase in the number of RAC(7.340±0.620 vs 5.013±0.738,P<0.001),the microvessel count(3.855±0.717 vs 2.375±0.705,P<0.001) and eNOS immunostaining in comparison with hyperoxia-exposed placebo-treated animals.Conclusion Treatment with sildenafil during hyperoxia exposure is associated with improved alveolar structure.Treatment of preterm infants with sildenafil may reduce the risk of developing bronchopulmonary dysplasia.The endogenous NOS may play a joint role. |