Cyclic motor activity and trophicity after jejunal resection and bypass in rats

Abstract

The aim of the study was to examine the changes in intestinal motility induced by an extensive jejunal resection and bypass in rats using an electromyographic technique. The relationship, if any, between the development of motility and adaptive modifications of intestinal trophicity was also studied. A massive jejunal resection, preserving a 7-cm segment distal to the ligament of Treitz, was performed in one group of animals. In a second group, the jejunum was bypassed as a self-emptying blind loop. Two sham-operated groups underwent transection and reanastomosis on the proximal jejunum or ileum. Electromyographic activity was studied at the 10th and 30th postoperative days by means of electrodes implanted throughout the remaining or bypassed bowel and was expressed by means of the pattern of recurrence of the migrating myoelectric complex (MMC). After a month, the animals were sacrificed. Mucosal and muscular wet weight and protein content (mg/cm) of the intestine were then determined. The results showed that 10 days after the jejunal resection in the fasting state, MMC cycle duration is different in the remaining jejunum and in the ileum. However, the distribution of MMC phases in the jejunum was modified and was similar to the one in the ileum. Thirty days after resection, MMC cycle duration, as well as phase distribution in the remaining jejunum, resemble the MMC patterns in the ileum. These changes were not observed after bypass. After the return of MMCs after postprandial inhibition produced by a meal, MMC duration in the ileum was greatly decreased until a month after jejunal resection. In contrast, the jejunal bypass did not produce this modification.

Effect of Extent of Resection on Intestinal Muscle Adaptation

“…However, our findings are consistent with those of Han-tile activity after resection [16]. Wittman et al [9], however, did not find a correlation between intestinal troson et al [8] who found that jejunal longitudinal muscle thickness increased 40% compared to a 20% increase phic changes and the recoordination of cyclic motor patterns after proximal resection in rats. This is not in the circular muscle thickness in rats.…”

“…The combined effect of lengthening and thickening of the longitudinal muscle layer would almost double the total mass of longitudinal muscle present. Wittman et al [9] reported increased muscle weight and protein content after resection, as well.…”

“…The only significant change in the circular muscle was an increase in length after 75% resection Changes in the intestinal muscle layers may play a role in the functional and motor adaptation observed whereas longitudinal muscle increased in both thickness and length. However, since circular muscle thick-following intestinal resection [1,9]. In vitro studies of muscle strips have demonstrated that there is a signess tended to increase in all these groups after resection, failure to demonstrate a difference may be related nificant reduction in the development of active tension and in the frequency and amplitude of phasic contracto the small sample size and individual variability.…”