Effect of dexamethasone on pulmonary fi brosis and endothelin-1 in lung tissue of rats

Objective To discuss the effect of dexamethasone on changes of endothelin-1（ET-1） in rats with pulmonary fibrosis induced by bleomycin（BLM）. Methods Rats were divided into model group,treatment group and control group.Pulmonary fibrosis was induced by endotracheal injection of bleomycin（5mg/kg）.Rats in treatment group were given intraperitoneal injection of dexamethasone（1mg/kg） every other day.Rats in control and model groups received saline instead of dexamethasone.On day 28,the rats were executed.ET-1 and hydroxyproline（HYP） levels in lung tissue were measured.Histopathological changes and endothelin-1（ET-1） in rats with pulmonary fibrosis were observed. Results The HYP and ET-1 levels were significantly higher in model group than in control and treatment groups（P＜0.01）. Conclusion ET-1 plays a role in development of pulmonary fibrosis.Dexamethasone has some inhibitory effects on pulmonary fibrosis,possibly by decreasing the ET-1 level.