Ischemic postconditioning does not attenuate ischemia-reperfusion injury of rabbit small intestine.

Objective— To determine whether ischemic postconditioning can attenuate intestinal ischemia–reperfusion (I–R) injury and has a beneficial effect on tissue blood flow during reperfusion. Study Design— In vivo experimental study. Animals— New Zealand White rabbits (n=6). Methods— Rabbits were anesthetized with pentobarbital, to avoid the preconditioning effects of volatile anesthetics, and ventilated with room air. Rectal temperature, hemodynamics, and normocapnia were maintained. After celiotomy, 3 jejunal segments were isolated in each rabbit for the following groups: (1) control, (2) I–R, and (3) I–R with postconditioning. I–R was induced by a 45-minute occlusion of the segment jejunal artery followed by 2-hour reperfusion. The postconditioning segment had 4 cycles of 30-second reperfusion and 30-second reocclusion during the initial 4 minutes of reperfusion. Stable isotope-labeled microspheres were used to measure intestinal blood flow at baseline, end occlusion, and end reperfusion. At the end of reperfusion, intestine segments were harvested and the rabbits euthanatized. A semiquantitative histopathologic evaluation (0–5) was conducted by a single, blinded observer. Wet-to-dry weight ratios were calculated to assess intestinal edema. Results— There was no significant difference in grade of necrosis, tissue wet-to-dry weight ratios, or blood flow at any time point between ischemic and postconditioning groups. Conclusions— Ischemic postconditioning was ineffective in this model of intestinal I–R. Clinical Relevance— Further experimental studies will need to be performed before clinical application of postconditioning for intestinal ischemia.