Abstract： Objective To investigate the protective effects of poly-ADP-ribose polymerase inhibitor 3-aminobenzamide (3-AB) on lung injury in rats with severe acute pancreatitis (SAP) and to explore the mechanisms.Methods Thirty-six Wistar rats were randomly (random number) divided into three groups (n =12 for each group),namely sham operation (SO) group,SAP group and 3-AB-treated group.The model of SAP-associated lung injury was established by retrograde injection of 5％ sodium taurocholate (STC) into the biliopancreatic duct.In the treated group,3-AB in dose of 10 mg/kg was administered twice by intravenous injection 30 min before and 30 min after STC infusion.The survival rats were sacrificed 12hours after SAP modeling,and the serum amylase,lung wet/dry ratio and myeloperoxidase (MPO) activity were determined,and pathological scores of pancreas and lung tissue were evaluated under light microscope.Expressions of interleukin (IL) -1 β and IL-6 mRNA,tumor necrosis factor α (TNF-α) and inter-cellular adhesion molecule-1 (ICAM-1) protein were detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot,respectively. Results The serum amylase level,lung wet/dry ratio and MPO activity,IL-1β and IL-6 mRNA expressions,TNF-α and ICAM-1 protein levels were dramatically increased in SAP group ( P ＜ 0.05 ).Treatment with 3-AB significantly reduced these biomarkers in 3-AB group than in SAP group (P ＜ 0.05 ).Conclusions Poly-ADP-ribose polymerase inhibitor 3-AB exerts the protective and therapeutic effects on lung injury associated with severe acute pancreatitis through inhibiting intrapulmonary MPO activity and down-regulating the expressions of IL-1 β and IL-6 mRNA as well as the levels of TNF-α,and ICAM-1.