Is reperfusion injury an important cause of mucosal damage after porcine intestinal ischemia?

Background. intestinal ischemic injury is exacerbated by reperfusion in rodent and feline models because of xanthine oxidase-initiated reactive oxygen metabolite formation and neutrophil infiltration. Studies were conducted to determine the relevance of reperfusion injury, in the juvenile pig, whose low levels of xanthine oxidase are similar to those of the human being. Methods. Ischemia was induced by means of complete mesenteric arterial occlusion, volvulus, or hemorrhagic shock. Injury was assessed by means of histologic examination and measurement of lipid peroxidation. In addition, myeloperoxidase, as a marker of neutrophil infiltration, and xanthine oxidase-xanthine dehydrogenase were measured. Results. Significant ischemic injury was evident after 0.5 to 3 hours of complete mesenteric occlusion or 2 hours of shock or volvulus. In none of these models was the ischemic injury worsened by reperfusion. To maximize superoxide production, pigs were ventilated an 100% O-2, but only limited reperfusion injury (1.2-fold increase in histologic grade) was noted. Xanthine oxidase-xanthine dehydrogenase In,els were negligible (0.4 +/- 0.4 mU/gm). Conclusions. Reperfusion injury may not play an important role in intestinal injury under conditions of complete mesenteric ischemia and low-flow states in the pig. This may, result from low xanthine oxidase-xanthine dehydrogenase levels, which are similar to those found in the human being.