Protective effects of dexamethasone on early acute lung injury induced by oleic acid in rats

摘要

Objective: Whether alveolar edema could be cleared by alveolar epithelial is a key to the treatment and prognosis of ALI (acute lung injury). In this study, oleic acid(OA)-induced ALI model was established, the expression of α1 Nasup+/sup/Ksup+/sup-ATPase (NKA) and β1 Nasup+/sup/Ksup+/sup-ATPase were performed in vivo to investigate the mechanism of alveolar fluid clearance (AFC) in ALI and the effect of early low doses of dexamethasone on alveolar fluid clearance. Methods: In this study, Male rats were challenged by OA with or without dexamethasone (1 mg/kg, iv) post-treatment. Lung histopathology, blood gas, pulmonary vascular permeability, BALF IL-6, MPO and NKA activity of lung were examined. α1NKA and β1NKA mRNA and protein expression were detected. Results: The results indicated that compared with sham operated group, NKA activity, mRNA and protein expression of α1NKA and β1NKA were decreased in OA treated group, while wet/dry ratio, lung index, IL-6, and MPO activity were increased significantly. Pulmonary edema was obviously seen under light microscope. Those indexes were improved in dexamethasone treated group compared to OA treated group. Conclusion: The expression of NKA to decline for the lung injury is one important mechanism of pulmonary edema. Early low dose of dexamethasone treatment could suppress the expression of inflammatory mediators, improved lung epithelial-endothelial barrier permeability, increased the expressions of α1 NKA and β1 NKA mRNA, α1 NKA and β1 NKA protein level, stimulated NKA activity and decreased pulmonary edema. In conclusion, these observations suggest that early low dose of dexamethasone treatment has a protective effect on OA induced ALI.