Suk-Bae Moon, et al. 3 (oral and anal side of the loop). There were two different temporarily dissociated from each other. The mean AUC patterns of MMCs in the total bypass 4-week model: in- showed no significant changes between the 2-week and dependently pacing MMCs without temporal relationship 4-week model. within the loop (n = 3, Fig. 5B), and irregular, small ampli- tude contractions (n = 2, Fig. 5C). The mean amplitude, du- ration, interval and AUC of MMCs in each channel are shown in Table 1. Compared to the control, the amplitude DISCUSSION was attenuated in channel 2 and 3 (P = 0.000, 0.000, re- This study was performed in order to investigate the spectively), the duration was shortened in channel 2 (P = mechanism underlying the development of the blind loop 0.004), and the interval was shortened in channels 2 and 3 syndrome through the changes in MMC. Historically, (P = 0.001, 0.034). Compared to the 2-week model, the in- MMC has been a field of interest for physiologists study- terval was shortened more within the bypass loop (P = ing gastrointestinal motility, and most of the physiologic 0.001, 0.003). The direction of propagation could not be de- properties of MMC have been clarified by using native an- fined, though, as the contractions within the loop were imal bowel without any surgical manipulations, usually Table 1. MMC parameters are shown according to the recording site from each mouse model Model recording site Amplitude Duration (mN) (sec) Interval (sec) AUC (mN·sec/ wave) Control (n = 7) (34 MMCs) Channel 1 19.3 ± 5.8 37.8 ± 14.2 290.7 ± 141.0 664.7 ± 249.5 Channel 2 17.9 ± 5.9 39.9 ± 13.4 289.7 ± 145.9 759.6 ± 290.2 Channel 3 15.7 ± 7.3 41.6 ± 14.7 289.8 ± 143.3 1013.1 ± 639.4 Channel 4 16.0 ± 3.7 46.8 ± 16.2 289.5 ± 148.6 699.2 ± 453.0 Partial bypass 2 weeks (n = 4) (20 MMCs) Channel 1 14.3 ± 4.2a) 23.7 ± 7.4a) 165.5 ± 50.1a) 312.9 ± 92.2a) Channel 2 13.5 ± 4.1 24.1 ± 7.6a) 165.0 ± 39.7a) 389.8 ± 112.7a) Channel 3 10.1 ± 7.9a) 33.1 ± 8.9 165.5 ± 39.0a) 473.2 ± 194.5a) Channel 4 Irregular or undetectable MMCs Partial bypass 4 weeks (n = 4) (25 MMCs) Channel 1 8.9 ± 3.1a,b) 28.6 ± 16.3a) 300.0 ± 55.8b) 353.4 ± 176.2a) Channel 2 11.9 ± 5.6a) 35.7 ± 18.5b) 296.0 ± 64.4b) 523.6 ± 231.6a) Channel 3 10.3 ± 6.7a) 38.3 ± 16.5 294.5 ± 62.2b) 500.3 ± 155.1a) Channel 4 Irregular or undetectable MMCs Total bypass 2 weeks (n = 6) (20 MMCs) Channel 1 14.4 ± 6.6a) 29.3 ± 10.2a) 200.3 ± 59.0a) 345.5 ± 99.1a) Channel 2 8.7 ± 1.7a) 32.6 ± 11.6 234.2 ± 54.2a) 431.4 ± 148.7a) Channel 3 8.1 ± 2.3a) 52.4 ± 22.1 253.9 ± 51.1a) 547.2 ± 213.5a) Channel 4 MMCs not detected Total bypass 4 weeks (n = 5) (17 MMCs) Channel 1 MMCs not detected Channel 2 7.7 ± 1.6a) 28.8 ± 5.8a) 145.3 ± 58.4a,b) 396.4 ± 98.6a) Channel 3 7.1 ± 2.2a) 40.2 ± 9.8 191.5 ± 48.8a,b) 423.5 ± 137.1a) Channel 4 MMCs not detected MMC, migrating motor complex; AUC, area under the curve; Channel 1, proximal to the anastomosis; Channel 2, proximal loop; Channel 3, distal loop; Channel 4, distal to the anastomosis. a)P ＜ 0.05 compared to the control; b)P ＜ 0.05 compared to the 2-week model. 256 through ex-vivo observations. There have been only a few studies reporting physiological motility changes after sur- gical manipulation on gastrointestinal tract. Chang et al. [9] reported the loss of interstitial cell of Cajal (ICC) and slow wave in murine small bowel obstruction model. Yanagida et al. [10] showed the loss of ICC and slow wave, and decrease in contractile force 5 hours after intestinal transection and re-anastomosis in mouse, which were re- covered in 24 hours. However, none of these two previous studies dealt with the MMC in their animal model. To our knowledge, the present study is the first one demonstrat- ing the significant changes in MMC after surgical manipu- lation of the mouse intestine. It has been assumed that the bypass loop acts as a reser- voir, and stagnation with resultant bacterial overgrowth inevitably follows. Vantrappen et al. [11] assumed that de- creased or absent inter-digestive motor complex (which is equivalent to MMC in mouse intestine) might be related to the intraluminal bacterial overgrowth in human. Howev- er, the proof for such phenomenon was lacking. In this study, at least in cases of side-to-side anastomosis for par- tial bypass in mouse, we have shown that the changes in the direction of propagation of the MMCs from the normal aboral to oral propagation within the bypass loop might be responsible for stagnation of the bowel contents. As time progressed after partial bypass, the changes in the di- rection of propagation of the MMCs became more prominent. The reason for the changes in the direction of the MMCs cannot be clearly explained, but we speculate thesurgery.or.kr