Involvement of superoxide anion in the pathogenesis of simple mechanical intestinal obstruction.

BACKGROUND: Mechanism underlying the pathogenesis of mechanical intestinal obstruction has been suggested to be closely associated with bowel inflammatory response in which reactive oxygen metabolites might play an important role. This study was designed to examine the involvement of superoxide anion in the obstruction-induced intestinal injury. MATERIALS AND METHODS: Rats were randomly aasigned to four groups: sham, obstruction, obstruction with polyethylene glycol (PEG), and obstruction with polyethylene glycol-superoxide dismutase (PEG-SOD) groups. A ligation at the ileum 20 cm proximal to the cecum was created under anesthesia. The superoxide anion production and the pathological manifestations in the obstructed intestine were measured after 24 h of ligation. RESULTS: There were significant intestinal shortening, distension, fluid accumulation and mucosal damage in the segment proximal to the ligation site. Pronounced generation of superoxide anion was found in the obstructed intestinal segment. Supplement of SOD, a superoxide free radicals scavenger, ameliorated obstruction-induced bowel distension, fluid accumulation and mucosal damage. CONCLUSION: These data suggest superoxide anion is one of the important mediators in the pathophysiologic changes of simple mechanical intestinal obstruction.

Effects of oral arginine and glutamine on radiation-induced injury in the rat.

BACKGROUND: Exposure of the abdominal region to ionizing radiation is associated with serious untoward symptoms of intestinal dysfunction and some reports indicate that nutrient supplements may reduce these adverse effects. This study was designed to investigate the possible beneficial effects of oral arginine or glutamine supplementation on the radiation-induced tissue injury. MATERIALS AND METHODS: Rats were given one of three feeding regimens: standard diet and water (control group), diet and water containing 2% arginine (arginine group), diet and water containing 2% glutamine (glutamine group) for 3 days prior to radiation. All rats were then subjected to a single does of 1100 cGy to the abdomen. Several serum biochemical parameters and the histologic alterations in different segments of gastrointestinal tract and liver were measured 4 days after irradiation. RESULTS: All the arginine-fed rats developed diarrhea on Day 4 postirradiation, compared to 71% incidence in control rats and 86% in glutamine-fed rats. Serum levels of aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) in the arginine group were markedly higher than those in other groups. On histological examination, radiation caused more serious damage to various segments of intestine in the arginine-fed rats compared to rats on other feeding regimens. CONCLUSION: These observations seriously question the beneficial effects of arginine and glutamine supplementations on radiation-induced tissue injury.