The effects of ischemia and reperfusion on intestinal motility

Abstract

The interdigestive migrating motor complex (MMC) has been demonstrated to be a reliable indicator of intestinal motility and function. The effects of low perfusion on the MMC have never been studied. Fourteen newborn Yorkshire piglets (5 to 18 days old, weighing 2.9 ± 0.4 kg) underwent celiotomy under general anesthesia with placement of four jejunal electrodes (50 cm apart) as well as a superior mesenteric artery (SMA) Doppler flow probe and a pericardial catheter. Group 1 (n = 5) had operation alone. Group 2 (n = 9) had nonocclusive mesenteric ischemia induced by reversible cardiac tamponade for 5 hours between postoperative days 6 to 12. All subjects had MMC phase III electrical activity, cycling time, and propagation velocity recorded daily. In group 2 MMCs were recorded prior to and during ischemia, and during reperfusion. Group 2 animals had 75% ± 4% decrease in SMA flow during the tamponade period. During the ischemic period, the MMC cycling time (CT) increased from 67 ± 10 (mean ± SEM) to 98 ± 12 minutes ( P < .05) and MMC propagation velocity (PV) decreased to 4.2 ± 2.2 from a baseline value of 10.5 ± 1.5 cm/min ( P < .05). During reperfusion CT and PV values were not significantly different from baseline. The validity of this model is confirmed by the comparable baseline recordings in groups 1 and 2, and by the return of MMC to baseline values within 4 to 7 hours of reperfusion, as seen in group 2. Phase III was similar in all subjects and it was not affected by ischemia, indicating that intrinsic electrical activity of the bowel was not disrupted. These findings in the young piglet—an excellent model of human small bowel motility—demonstrate a dysfunctional MMC pattern induced by nonocclusive mesenteric ischemia. This may represent a key factor for development of bacterial overgrowth and translocation from the gastrointestinal tract during low perfusion states.