A Rat Model of Acute Lung Injury Induced by Lipopolysaccharide

Objective The Acute lung injury/acute respiratory distress syndrome(ALI/ARDS) has high morbidity and mortality.The mechanisms of both ALI and ARDS are still not fully elucidated.The purpose of this study was to establish a rat model of mild ALI,and to explore the mechanisms of ALI/ARDS.Methods There were 45 Sprague-Dawley rats weighing 250±20 g used in this experiment.Lipopolysaccharid(LPS) powder was reconstituted by sterile saline to a final concentration of 200 μg/mL.0.5 mL/kg LPS was instilled into the trachea via a needle.Lung tissue samples were taken at 4 h,12 h,24 h and 48 h after instillation of LPS,and histological examination by light and electron microcopy was performed.Bronchoalveolar lavage fluid(BALF) was collected to assess the presence of polymorphonuclear neutrophils(PMN) and albumin in BALF.Results All the rats survived during the experiment course.As compared to the control rats,the histological examination of LPS-treated group showed that ①pulmonary interstitial edema,② PMN and erythrocyte were accumulated in alveoli lumen,③ The damages in both type I and Ⅱ epithelial cells were found.The pathological alterations above mentioned were more serious in LPS-treat rats at 4～12 h after LPS treatment.The amount of PMN and albumin in BALF was significantly increased.Conclusion An acute lung injury model of rats can be successfully established by instillation of 0.5 mL/kg(200 μg/mL) LPS into the trachea.