Functional Innervation of the Isolated Bowel Segment By Engin Gtinel, Ayse Sahin, Fatma Caglayan, and ishak Akllhoglu Kon ya, Turkey Purpose:The aim of this study is to investigate whether there might be an eventual change in the enteric nerve responses to electrical field stimulation (EFS) of the isolated bowel segment (IBS) created by omentoenteropexy. Methods: In the experimental group, an IBS was created in 10 rats using the omentum as the host organ by dividing of its mesentery 4 weeks later. In the control group, a jejunal loop of identical site and length to the IBS was studied in another 10 rats as normal jejunal segment. Longitudinal muscle strips were prepared from the IBSs (n = 20) and the normal jejunal segments (n = 20). The effects of atropine, tetrodotoxin, L-arginine, and L-nitroarginine methyl ester (L-NAME) on the responses to transmural EFS were examined in both the IBS and normal jejunal segment using the isometric tension recording technique. Results: Transmural EFS of the IBS strips produced contrac- tile responses. Atropine and tetrodotoxin abolished the EFS- induced contractions of the IBS. Moreover, EFS-induced contractions were increased by the application of L-NAME, and were decreased by the application of L-arginine in the IBS. Mean percent change of IBS’s contraction was not found statistically different from mean percent change of normal jejunal segment’s contraction on the effects of L-NAME and L-arginine. Conclusion: These results suggest that the IBS, created by omentoenteropexy, produced enteric nerve responses to EFS as seen as in normal jejunal segment. J Pediatr Surg 34:387-389. Copyright o 7999 by W.B. Saun- ders Company. INDEX WORDS: Isolated bowel segment, omentoenteropexy, functional innervation. C REATION of an isolated bowel segment (IBS) has been attempted using a subcutaneous tunnel, the abdominal wall (myoenteropexy), and the liver (hepatoen- teropexy) as host organs after division of the mesenteric vessels.1-3 Their functional studies proved that the motil- ity and absorption capabilities of the IBS after mesenteric division remained norma1.4-6 In a previous study, we presented the technique for creation of an IBS in rats using omentum as the host organ when its mesentery was divided 4 weeks after omentoenteropexy. Viability of such an IBS was documented by histological observation at the level of the omentoenteropexy.7 The question remained as to whether it would be suitable for segmental esophageal substitution, bowel reconstruction, and by its lengthening procedure for surgical treatment of short bowel syndrome. The aim of this study is to investigate whether there might be an eventual change in the enteric nerve response to electrical field stimulation of the IBS, created by omentoenteropexy. Using the isometric tension recording technique, the functional innervation of the IBS was compared with that of the normal jejunum. MATERIALS AND METHODS Twenty Sprague-Dawley rats (180 to 240 g) were equally divided in to experimental and control groups, and anesthetized using intraperito- neal ketamine hydrochloride. Creation of the IBS In the experimental group, the abdomen was entered by a midline incision. A lo-cm-long jejunal loop was isolated with the mesentery beginning 20 cm distal from the ligament of Treitz to create the IBS. The remaining bowel was reanastomosed to maintain bowel continuity. The omentoenteropexy was performed as described previously.7 A longitudinal seromuscular incision was made on the antimesenteric border on the IBS. The incision line was fixed to a pedicle of greater omentum and sutured with running 5-O Vicryl. Both IBS ends were sutured over, creating a closed loop in the abdominal cavity. The abdomen was closed in one layer using 3-O Prolene. After fasting for 24 hours, a standard rat diet was started. Four weeks after the first operation, the abdomen was reentered with the animal under general anesthesia. The mesentery of the IBS was ligated and divided in 10 rats. The IBS was then totaly free of its mesenteric blood supply. The abdomen was again closed in one layer using 3-O Prolene. All rats underwent reoperation 48 hours after division of the IBS mesentery. The IBS and the omental pedicule were resected en bloc. In the control group, the abdomen was entered by a midline incision, and a jejunal loop of identical site and length to the experimental group was resected in 10 rats in the first step of the procedure. From the Departments of Pediatric Surgery and Pharmacology, Medical School of SelFuk University, Kenya, Turkey. Address reprint requests to Engin Giinel, MD, Assistant Professor of Pediatric Surgery, Babalzk mah. Vatan cad. Kartal Sitesi No:12/5 42040 Kenya, Turkey. Copyright o 1999 by WB. Saunders Company 0022-3468/99/3403-0003$03.00/O Journal of Pediatric Surgery, Vol34, No 3 (March), 1999: pp 387-389 387