MOTILITY OF ISOLATED BOWEL SEGMENT IOWA MODEL-III

The isolated bowel segment (IBS) is an amesenteric segment of bowel that is devoid of extrinsic nerves and yet is viable with motility and absorption preserved after its mesentery is completely severed. The IBS is created by initial coaptation of a loop of bowel to a host organ, such as muscle (Iowa model I), liver (Iowa model II), or intestine, and secondary severance of its mesentery several weeks later. In previous studies using Iowa models I and II, the viability, motility, and absorption of the IBS were preserved by vascular collaterals, which form across the coaptation. In rats, an IBS was created in the jejunum by initial enteroenteropexy (Iowa model III), followed by its mesenteric division five weeks later. At the second laparotomy, bipolar electrodes were implanted in the IBS and the adjacent jejunum. One week later, myoelectrical recording was performed during a fasting state. Coordinated aborad propagation of migrating motor complex (MMC) was observed in the IBS. The MMC period was 16.9 +/- 1.7 and 19.3 +/- 0.8 min in the intact bowel, and 22.8 +/- 0.8 min in the IBS (P = 0.1). After feeding, the MMC in the IBS was replaced by irregular spike burst activity similar to that observed in the intact bowel. This study concludes that the IBS Iowa model III can be used for studies of bowel physiology.