Objective:To investigate the mechanism of the changes of the intestinal mucosal barrier in Severe acute pancreatitis.Methods:Twenty patients with Severe acute pancreatitis were admitted and 10 volunteers as the control group.The levels of serum tumor necrosis factor alpha(TNF_?)、nitric oxide(NO)、diamine oxidase(DAO) and the concentration of plasma endotoxin(ET) were measured.The ratio of lactulose to mannitol in urine was detected by HPLC with Pulsed Electrochemical Detection.Results:Compared with the control group,significantly increasing parameters could be seen in all the patients with Severe acute pancreatitis,including the ratio of lactulose to mannitol in urine (P