ORNITHINE DECARBOXYLASE IS INVOLVED IN REPAIR OF SMALL-INTESTINE AFTER ISCHEMIA-REPERFUSION IN RATS

To assess whether ornithine decarboxylase (ODC) is involved in mucosal repair after ischemia-reperfusion (I/R), two approaches were used: 1) measurement of mucosal ODC activity at different intervals after I/R, and 2) inhibition of ODC activity with alpha-difluoromethylornithine (DFMO, an irreversible inhibitor). In the first series of experiments, rats were allowed to recover after superior mesenteric arterial occlusion (10 min) before harvesting the intestinal mucosa for measurement of ODC activity. ODC activity increased markedly 6 h after I/R, and > 72 h were required for enzyme activity to return to normal. DFMO treatment completely abolished the I/R-induced increase in ODC activity. In another series of experiments, rats with an intestinal lymph fistula were infused intraduodenally at 3 ml/h with vehicle or 2% DFMO in vehicle immediately after I/R. Lipid absorption was measured at 24 and 48 h after I/R. In the DFMO group, lymph radioactive lipid output at 24 h after I/R was significantly lower compared with time-matched sham-operated controls. Lymph lipid output in rats receiving the vehicle was restored to a normal level at 48 h after I/R. However, this restoration of normal lymphatic lipid transport at 48 h I/R was not observed in the DFMO group. These observations indicate that ODC activity plays an important role in the repair process that results in complete restoration of mucosal function 2 days after I/R.