Synergy of ischemic pre- and immediate post-conditioning attenuates intestinal ischemia-reperfusion injury in rats

Abstract

Ischemic postconditioning (IPo) is similarly effective as ischemic preconditioning (IPC) in attenuating intestinal ischemia-reperfusion injury (IIRI). It is unknown whether IPC and IPo can confer synergistic effect in attenuating IIRI, and whether delayed IPo is as effective as immediate IPo. Rats were randomly divided into six groups (n=8 each): Sham; IIRI, produced by clamping the superior mesenteric artery (SMA) for 60 min followed by 60 min of reperfusion; IPC, elicited by 10 min ischemia followed by 10 min reperfusion before inducing IIRI; immediate IPo, achieved by 3 cycles of 30 s reperfusion and SMA reocclusion immediately at the onset of reperfusion; Joint IPC and immediate IPo; and delayed IPo, achieved by 3 cycles of 30 s reperfusion and SMA reocclusion started 3 min after the onset of full reperfusion. Intestinal injury evidenced by increases in Chiu's scores and intestine tissue wet-to-dry weigh ratio as well as elevations of plasma tumor necrosis factor-alpha and intestinal tissue lipid peroxidation product malondialdehyde were apparent in the IIRI untreated group. These changes were significantly attenuated by IPC, immediate IPo and their combination, but not by delayed IPo. Joint IPC and immediate IPo conferred superior protective effects than they were applied alone (P<0.05), indicative of a synergy of ischemic pre- and immediate post-conditioning in attenuating IIRI in rats.