Protective Effect Of Dexmedetomidine Pretreatment On Acute Lung Injury Induced By Lipopolysaccharidein Rats

Objective： To investigate the protective effect of dexmedetomidinepretreatment on acute lung injury induced by lipopolysaccharide (LPS) in rats.Methods：A total of forty-five male Sprague-Dawley rats weighing250~300g were randomly divided into three groups: saline control group (group NS,n=15), the acute lung injury group (group ALI, n=15) and the dexmedetomidinepretreatment group (group Dex, n=15).The rats in the LPS group wereintratracheally administered with LPS (5mg/kg) to duplicate an acute lung injurymodel. In the group Dex, the rats were given50μg/kg of DEX intraperitoneally30min before LPS application. Six hours after LPS administration, arterial bloodwas drawn for blood gas analysis, and serum samples were collected forinterleukin-6(IL-6) and tumor necrosis factor (TNF)-alpha (TNF-α)measurement,and the pulmonary tissues were harvested for pathological evaluation, wet/dryratio measurement, biochemical analysis of myeloperoxidase (MPO). Results：Compared with control group, acute lung injury was induced inthe ALI group, which was indicated by severe pulmonary tissue damage inhistopathology and significantly decreased PaO2, increased wet/dry weight ratiotogether with the enhanced of MPO activities. The levels of TNF-α and IL-6were significantly higher in the ALI group than NS group. dexmedetomidinepretreatment significantly improved LPS-induced lung pathological changes andincreased PaO2, inhibited MPO activities, and decreased TNF-α and IL-6levelsand wet/dry weight ratio.Conclusions：Dexmedetomidine pretreatment can protect acute lung injuryinduced by LPS through inhibition of activation of neutrophil in lung tissue andexpression of TNF-α and IL-6.