¡¾Abstract¡¿ AIM: To explore the effects of DDFA on cell apoptosis and expressions of Bax and Bclª²2 in lung tissue of rats with severe acute pancreatitis(SAP). METHODS: 45 rats weighting 200ª²250 g were randomized into 3 groups: control group (n=15), SAP group (n=15) and DDFA group (n=15). The models of SAP were established by the injection of 200 g/L arginine solution ip(once a hour for 2 h) into the rats. At the 24, 48 and 72 h after establishment of models, serum amylase, TNFª²a and calcium were determined. The left lungs were taken for light and electron microscopic observation. Cell apoptosis in lung tissue was determined by TUNEL method. Expressions of Bax and Bclª²2 were detected by immunohistochemical staining of SABC. RESULTS: In the SAP group, serum amylase, TNFª²a, apoptotic index, expressions of Bax and Bclª²2 markedly increased. Lung tissue injuries were significant under a light microscope. As compared with SAP group at the same phase, serum amylase, TNFª²a, apoptotic index and expressions of Bax in DDFA group decreased significantly. While the expression of Bclª²2 increased significantly. The injury of lung tissue was relieved by DDFA. CONCLUSION: The apoptosis and the expressions of Bax and Bclª²2 in lung tissue might be involved in pathogenesis of SAP. DDFA administration in the early stage is helpful for diminishing lung injury induced by SAP. ......