Objective: Intra-abdominal hypertension(IAH),commonly seen in various critical surgical cases,may lead to body ischemia and reperfusion damage and result in serious inflammatory response.Previous studies were concentrated mostly on the risk of IAH,but less on IAH-induced reperfusion damage.The purpose of this study was to investigate the impact of IAH on the intestine.Methods: A total of 120 Sprague-Daley rats were divided into an abdominal compartment syndrome(ACS) group,with intra-abdominal pressure(IAP) increased to 20 mmHg,an ACS/decompression(ACS/DE) group,with increased IAP followed by decompression,and two control groups,with IAP unchanged.Malondialdehyde(MDA),myeloperoxidase(MPO),glutathione(GSH) and glutathione peroxidase(GSH-Px) enzyme of the intestine were measured.Additionally,ileal tissues were taken for histopathological examinations and apoptosis detection;the liver,spleen,and mesenteric lymph nodes were obtained for microbiological analysis.Results: In the presence of IAH,MDA and MPO were increased,while GSH and GSH-Px were decreased.Microbiological analysis suggested bacterial translocation across the gut.Morphological examinations indicated that Chiu's score and apoptotic index in the ACS/DE group were the highest in the four groups.Conclusion: Oxidative stress plays an important role in the intestinal damage and bacterial translocation in abdominal compartment syndrome.Additionally,the influence of oxygen free radicals occurs mainly during the reperfusion rather than the IAH period.