Effect of captopril on serum TNF-α level in acute lung injury rats induced by HCL

Objective:To observe the effect of captopril on the tumor necrosis factor-α(TNF- α) level and arterial blood gases in acute lung injury(All) induced by HCL in rats,and to analyze its protective mechanism.Methods:Fifty Wistar rats were selected and randomly divided into three groups,with 20 rats in Group Ⅰ and Ⅱ,respectively and 10 animals in Group Ⅲ.ALI model was constructed by intratracheal injection of diluted hydrochloric acid(pH=1.25.1.2 mL/kg).Group Ⅰrats received not any treatment after construction of AM model.Group Ⅱ rats were treated with captopril(5 mg/kg,i.p.) 5 min after induction of ALI.Group Ⅲ served as normal control without any treatment.Ninety minutes after construction of ALI model,all the rats were sacrificed.Blood was withdrawn for detection of TNF- α level and arterial blood gases index.And lung tissue slices of the three groups were prepared for observation of pathologic histology changes.Results:TNF- α level in serum of Group Ⅰ and Ⅱ rats was significantly higher than that in Group Ⅲ(P0.05),while TNF- α level in serum of Group Ⅱ was significantly lower in Group Ⅰ(P0.05).PaCO_2 level was significantly higher(P0.05),while PaO_2 was significantly lower(P0.05) in Group Ⅰ and Ⅱ rats than those in Group Ⅲ.PaCO_2 was significantly lower(P0.05) and PaO_2 was significantly higher(P0.05) in Group Ⅱ than those in Group Ⅰ.Histological observation showed diffuse congestion and severe edema of luug tissue,obvious thickening and structure damage of alveolar walls and a large amount of neutrophil infiltration in Group Ⅰ rats.Group Ⅱ rats showed mild edema of lung tissue;only a small portion of alveolar walls showed thickening and only a few of neutrophil infiltration could be observed.The degree of injury was remarkably slighter than that of Group Ⅰ rats.Group Ⅲ rats showed clear lung tissue structure and normal morphology:alveolar walls were uniform and the margin was smooth and few neutrophil could be observed.Conclusions:Captopril can significantly reduce serum TNF- α level,elevate PaO_2 and reduce PaCO_2 in rats with ALI.It has a protective effect on ALI rats.