J Korean Surg Soc 2011;80:251-259 DOI: 10.4174/jkss.2011.80.4.251 ORIGINAL ARTICLE JKSS Journal of the Korean Surgical Society pISSN 2233-7903ㆍeISSN 2093-0488 Migrating motor complex changes after side-to-side ileal bypass in mouse ileum ex-vivo: mechanism underlying the blind loop syndrome? Suk-Bae Moon1, Kyu-Joo Park1, Jung-Sun Moon1,2, Eun-Kyoung Choe1, In-Suk So2, Sung-Eun Jung1 Departments of 1Surgery and 2Physiology, Seoul National University College of Medicine, Seoul, Korea Purpose: This study was intended to investigate the migrating motor complex (MMC) changes after ileal bypass in ex-vivo mouse models. Methods: Partial (side-to-side) and total bypass (occlusion of proximal part of bypassed loop) were per- formed on ileums of female Institute of Cancer Research mice. After 2 and 4 weeks, the bypassed segments were harvested and MMCs were recorded at 4 different sites ex-vivo. Amplitude, duration, interval, direction of propagation, and the area under the curve (AUC) of MMCs were measured and compared to those of the controls. Results: In control mice (n = 7), most MMCs propagated aborally (91.1%). After 2 weeks of partial bypass (n = 4), there was a significant decrease in both ampli- tude and AUC, and orally-propagating MMCs increased significantly (45%, P = 0.002). Bidirectional MMCs (originating in the bypassed loop and propagating in both directions) were also observed (10%). The amplitude of the MMCs remained de- creased at 4 weeks after partial bypass (n = 4), and neither the AUC nor the direction of propagation showed significant changes compared to 2 weeks. Similarly, in the total bypass model, both the amplitude and AUC of the MMCs decreased sig- nificantly compared to controls. In contrast to partial bypass, 95% of the MMCs within the bypassed loop propagated abor- ally after 2 weeks (n = 6), which was similar to the control state. After 4 weeks (n = 5), however, MMCs either lost their tempo- ral relationship or completely disappeared. Conclusion: The changes in propagation direction of the MMCs in the partially bypassed loop may contribute to stagnation of bowel contents and the development of blind loop syndrome. Key Words: Myoelectric complex, Migrating, Mice, Ileum, Jejunoileal bypass INTRODUCTION In surgical practice, small to small or small to large bow- el bypass is performed for various settings such as radia- tion enteritis or Crohn’s disease. However, blind loop syn- drome is a well-documented complication following the Received July 29, 2010, Accepted November 10, 2010 side-to-side anastomosis of the intestine. Stagnation of the intestinal contents and subsequent bacterial overgrowth in the bypassed loop has been known to be the cause [1]. Re-entry of the intestinal contents through the lateral anastomosis into the bypass loop might be related to the stagnation [2]. Clinically, some surgeons used proximal Correspondence to: Kyu-Joo Park Department of Surgery, Seoul National University Hospital, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul 110-744, Korea Tel: ＋82-2-2072-2901, Fax: ＋82-2-766-3975, E-mail: kjparkmd@plaza.snu.ac.kr This work was presented by poster at the Digestive Disease Week on May 4, 2010 in New Orleans, LA, USA cc Journal of the Korean Surgical Society is an Open Access Journal. All articles are distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Copyright © 2011, the Korean Surgical Society