The isolated bowel segment (Iowa Model II): absorption studies for glucose and leucine

A model of the isolated bowel segment (IBS, Iowa Model II) was successfully created in experimental animals using a new surgical technique we developed. The IBS is completely free of its mesenteric attachment, yet its viability is preserved. The technique consists of two staged procedures: (1) initial enteropexy between the anterior margin of the liver and the antimesenteric border of the IBS with its ends forming cutaneous stomas; and (2) division of the IBS mesentery 5 weeks later. The IBS is nourished by vascular collaterals that form at the hepatoenteropexy during the interval between these two procedures. Our previous studies demonstrated preserved viability and motility in the IBS. This study was undertaken to test absorption in the IBS. In 25 rats (experimental group), the IBS (Iowa Model II) was created using an 8-cm-long isolated segment of jejunum. In 15 rats (control group), an 8-cm-long segment of jejunum was arranged to form a Thiry-Vella loop. Five weeks later, the IBS mesentery was divided in the experimental group, and sham laparotomy was performed in the control group animals. Absorption of glucose and leucine was studied in 13 rats of the experimental group and 6 of the control group using a constant single perfusion technique at 3, 8, and 11 weeks after the initial operation. The results were compared between the two groups. There was a 25% to 35% reduction in absorption of glucose and leucine in both groups with the advance of time, but no significant difference was observed between the groups except in leucine absorption at 11 weeks after the initial operation. This study concludes that absorption of glucose and leucine is preserved in the IBS after its mesentery is divided, suggesting that the IBS can be used as a functioning bowel for bowel reconstruction.