Preconditioning of the Small Intestine to Ischemia in Rats

Measures reflecting the state of the small intestine were studied in rats after ischemia lasting 90 min produced by clamping the superior mesenteric artery and reperfusion for 30 min. Preconditioning of the intestine to ischemia was induced by producing intestinal ischemia for 10 min followed by 10 min of reperfusion (ischemic preconditioning), 30-min limb ischemia with 15-min reperfusion (distant ischemic preconditioning), and i.v. L-arginine. The smallest amount of damage to the intestine after 90 min of ischemia and 30 min of reperfusion was seen in the group of rats subjected to ischemic preconditioning. The protective effect of ischemic preconditioning was partially blocked by administration of N--nitro-L-arginine (a blocker of NO synthesis). Doses of L-arginine also had protective effects, though these were smaller than those of ischemic preconditioning. Preliminary ischemia-reperfusion of the limb had no effect on the state of the intestine. Thus: 1) ischemic preconditioning of the intestine is partially associated with activation of nitric oxide synthesis, and 2) distant ischemic preconditioning did not protect the intestine.