Ischemic Postconditioning Does Not AttenuateIschemia-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.