Effect Of Different Tidal Volume Ventilation On The Apoptosis Of Alveolar Epithelial Cell And Pulmonary Macrophage In Rat

Objective:To investigate the changes of the expressing of Bcl-2 and bax in alveolar epithelial cell and pulmonary macrophage,and how the tatio of Bax/Bcl-2 modulate the apoptosis after mechanical ventilation with different tidal.Methods:24 healthy SD rats were randomly divided into 4 groups: Group A(control group),Group B(Vt=10ml/kg),Group C (Vt=20ml/kg)and Group D(Vt=40ml/kg).All the animals were received the tracheotomy under anesthesia for ventilation with different tidal volume except Group A.After the ventilation has overd for 24 hours,we examined the lung histopathology,W/D ratio and WBC in BALF to evaluate the lung injury,and examined the apoptotic cell death by TUNEL technique and Bax/Bcl-2 expression using immunohistochemistry.Result:1.Lung histopathology,W/D ratio and WBC in BALF:There is no differences between A and B(P＞0.05);compare to A and B,the lung histopathology,W/D ratio and WBC in BALF is higer in goup C and highest in group D(P＜0.05).2.TUNEL technique:There is no differences between A and B(P＞0.05);compare to A and B,the AI is higer in goup C and highest in group D(P＜0.05).3.Immunohistochemistry:Bcl-2 was highest in group A and B(there is no differences between these tow groups,P＞0.05),and lowest in group D(group B vs group C,group C and group D,P＜0.05);On the other hand,Bax Immunohistochemistry showed correlated reverse changes compared to Bcl-2 expression.Conclusions:1.Low VT ventilation didn't increase the dangerous of lung injury,2.Normal and high VT ventilation could increase the biotrauma,and the injury degree was related with tidal volume.3.Normal and high VT ventilation could modulates expression of Bcl-2 and Bax to alter apoptosis in alveolar epithelial cell and pulmonary macrophage in rat,which support the presumption that the apoptosis of alveolar epithelial cell and pulmonary macrophage in lung play an important role in VILI,and the ratio of Bax/Bcl-2 was the one of most important effects in this pathway.