Abstract:

To investigate the effect of instilled air on lipopolysaccharide (LPS)-induced mouse model of acute lung injury (ALI) and to provide evidence for establishment of more effective intratracheal instillation. Methods Forty-five male C57BL/6J mice were randomly divided into control group (n=15),LPS group (n=15),and LPS+air group (n=15).The mice in LPS and LPS+air groups were instilled with LPS to establish ALI models by exposed intratracheal instillation method.LPS was instilled intratracheally into the lungs of the mice in LPS+air group with  1 mL syringe prefilled with 100  μL air and the mice in control group were not treated.The detection of the biochemical indexes in bronchoalveolar lavage fluid (BALF),cell differential counting in BALF,lung wet/dry weight (W/D) ratio,and the morphological observation of lung tissue  were performed 24 h after  intratracheal instillation.
Results Compared with control group,the activities of alkaline phosphatase (ALP) and lactate dehydrogenase (LDH),the  concentrations of total protein  in BALF,the amounts of total cells and neutrophils in BALF,and lung W/D ratios of the mice in LPS and LPS+air groups  were significantly increased (P<0.05).Compared with LPS group,the activities of ALP and LDH,the concentration of total protein in BALF,the amounts of total cells and neutrophils in BALF,and lung W/D ratio  in LPS+air group　were significantly increased(P<0.05).The  histological observation results of lung tissue showed that there were differ
ent degrees of fluid accumulation,neutrophils infiltration,congestion and hemorrhage of the mice in LPS+air and LPS groups compared with control group;there were more protein-rich fluid,neutrophils and erythrocytes accumulated in alveolar spaces of the mice in LPS+air group compared with LPS group.
Conclusion The instilled air can be used to improve the method of intratracheal instillation and establish the more reliable experimental animal model of ALI.

Key words: acute lung injury, lipopolysaccharide, intratracheal instillation, instilled air