Objective To explore the effect of N-acetylcysteine(NAC)on the expression and clinical significance of cyclooxygenase-2(COX-2)in acute lung injury(ALI)tissue of rats.Methods Lipopolysaccharide(LPS)was applied to induce rats model with ALI.NAC was utilized for intervention.Rats were divided into three groups:contrast group,model group and NAC group.Immunohistochemical staining was performed to detect the expression of COX-2.The average optical density and the rate of positive area of COX-2 expression were an...