Abstract： Objective To investigate the protective effect of hydrogen-rich saline on renal injury of rats with acute necrotizing pancreatitis and its mechanism.Methods Fifty-four male Wistar rats were randomly divided into three groups:sham operation group (SO group),acute necrotizing pancreatitis group (ANP group) and hydrogen-rich saline treatment group (HRS group),with 18 rats in each group.Acute necrotizing pancreatitis model was induced by retrograde injection of 5％ sodium taurocholate into the biliopancreatic duct.Hydrogen-rich saline was injected through the tail vein (6 ml/kg) and subcutaneously (20 ml/kg) at 5 minutes after the operation in HRS group.The rats of SO group underwent laparotomy with gentle pancreas,duodenum manipulation only.The rats of SO group and ANP group were administered with intravenous (6 ml/kg) and subcutaneous (20 ml/kg) injection with saline.Rats in each group were sacrificed at 3,12 and 24 h after the operation.The levels of serum amylase,creatinine,urea nitrogen were determined.Fresh renal tissue was prepared and renal malondialdehyde (MDA),renal superoxide dismutase (SOD) activity were measured.Pathological changes of renal and pancreas tissues were examined and pathological scores were recorded.Ultrastructural changes of renal tissues were observed under a transmission electron microscope.Results The levels of serum amylase,creatinine,urea nitrogen,renal histopathological scores,MDA were (5396 ± 500) U/L,(80.3 ± 11.6) U/L,(14.1 ± 2.1) U/L,(448.3 ± 36.8),(7.03 ± 0.85) nmol/mg,which were significantly higher than those in SO group (P ＜ 0.05),but the renal SOD activity was (35.2 ± 5.28) U/mg,which were significantly lower than that in SO group (P ＜ 0.05).The corresponding values in HRS group were (5448±967)U/L,(41.9±8.6)U/L,(7.2± 1.3)U/L,(315.2±39.6),(5.15±0.35) nmol/mg,which were significantly lower than those in ANP group,but were significantly higher than those in SO group (P ＜ 0.05).The renal SOD activity was (49.1 ± 6.79) U/rag,which were siguificantly higher than that in ANP group,but was significantly lower than that in SO group (P ＜ 0.05).Conclusions Hydrogen-rich saline has a protective effect on renal injury of ANP,and its mechanism may be related to anti-oxidative stress.