Changes in Migrating Motor Complex after Bowel Obstruction in the Murine Ileum

ABSTRACT

PURPOSE: Partial obstruction of the small bowel causes hypertrophy of smooth muscle cells and enteric neurons. After small bowel obstruction, slow waves have also been reported to disappear or to be greatly reduced at the oral site of the obstruction in the murine ileum. The purpose of this research was to study the changes in migrating motor complexes (MMCs) after partial obstruction in order to compensate for the attenuated function of slow waves. METHODS: A ring of film (6 mm in length, 4 mm in internal diameter) was placed over the small intestine 5-6 cm oral to the ileocecal valve in 8-10 wk old female ICR mice. These rings resulted in a partial obstruction of the intestine after 2 wk. The mechanical activities of the small intestine were recorded and the amplitude, interval, and half-duration of the MMCs were analyzed. RESULTS: The MMCs from a partially obstructed ileum occurred every 1.58+/-1.06 min and had a half-duration of 6.90+/-5.54 sec. The interval and the half-duration of the control MMCs were 3.60+/-1.11 min and 31.5+/-11.4 sec, respectively. The difference in interval and the half-duration of the MMCs reached statistical significance (P=0.03; P=0.00). The amplitude and the area under the curve (AUC) of the MMCs of the obstructed ileum were much higher than those of the control (31.3+/-8.86 vs. 6.05+/-1.92 mN; 161.18+/-44.09 vs. 72.95+/-2.45 mN . sec/MMC wave; P=0.00, 0.02). CONCLUSION: The MMCs with higher amplitude and AUC, with shorter interval, and with shorter half-duration, compared with those of the control, were recorded from the partially obstructed murine ileum, reflecting efforts to overcome the effect of obstruction by increasing the power of contractions.