Study Of Mechanisms Of Ventilator-induced Lung Injury In An Old Rat Model And Effects Of Salbutamol

Objective:To investigate mechanisms of ventilator-induced lung injury and protective effects of salbutamol on that in an old rat model.Methods:24 healthy male wista rats(14 months old) were randomly divided into three groups to receive two ventilation protocols for 4h,after anesthesia was administered and tracheotomy was performed:group A was served as control groups(VT=8ml/kg,R=40/min),group B received large tidal volume ventilation(VT=40ml/kg,R=15/min),group C received the same tidal volume ventilation as group B with the treatment of salbutamol.After ventilation,all rats were killed.We detected wet to dry right lung weight ratio(W/D),the concentration of total protein and albuminin in bronchoalveolar lavage fluid(BALF),the activity of tNOS,iNOS,SOD and XOD and the level of MDA, TNF-α,IL-2,IL-6 and IL-8 in lung tissue bomogenate.Lung histopathology was assessed among three groups using light and transmission electron microscopy.Results:After 4h mechanical ventilation,wet to dry right lung weight ratio(W/D) and the concentration of total protein and albuminin in BALF were significantly lower in group C than in group B.The activity of tNOS,iNOS, SOD and XOD in lung tissue bomogenate was significantly higher in group C than B.The level of MDA,TNF-α,IL-2 and IL-6 in lung tissue bomogenate was significantly lower in group C than B.Histopathologic findings demonstrated more infiltrating WBC and destructive change of the alveolar wall in group B than A and C.Transmission electron microscopy studies show fewer alveolar epithelial cells damage in group C than group B. Conclusions:The results suggest that injurious mechanical ventilation mediates inflammation,redox imbalance and apoptosis in ventilator-induced lung injury.Salbutamol has obvious protective effects on VILI.