Reperfusion mucosal damage after complete intestinal ischemia in the dog: the effects of antioxidant and phospholipase A2 inhibitor therapy.

In a recent study, reperfusion mucosal injury was demonstrated in a rat model of total ischemia if venous congestion was avoided. The aims were to examine the possibility of reperfusion damage in a canine model involving 2 hours of complete segmental ischemia and to investigate the effects of antioxidant therapy or pretreatment with nonspecific phospholipase A2 inhibitors on postocclusive mucosal changes. Tissue samples were evaluated histologically in a blind manner, according to a 0 to V grade scale. The degree of mucosal damage was statistically significantly increased during the 30-minute reperfusion period. Similarly, 2 hours of total ischemia followed by 30 minutes of reperfusion produced significantly more tissue lesions than did 2 1/2 hours of ischemia without reperfusion. Oral allopurinol pretreatment supplemented by an intravenous dose, or oral allopurinol in combination with a superoxide radical scavenger, resulted in a significant amelioration of postischemic histologic changes. Pretreatment with a nonspecific phospholipase A2 inhibitor (methylprednisolone, dexamethasone, or quinacrine) was ineffective in diminishing the reperfusion injury in either case. The results suggest that reperfusion injury may develop even after complete intestinal ischemia, and this damage can be attenuated by inhibiting the capacity of xanthine oxidase to generate reactive oxygen intermediates.