Roles of Interstitial Cells of Cajal in Intestinal Transit and Exogenous Electrical Pacing

The aims of this study were to investigate the role of interstitial cells of Cajal (ICCs) on small intestinal transit and its responses to exogenous pacing in W/W^v mice. Eleven W/W^v mice and their controls implanted with four pairs of gastrointestinal electrodes were used for testing the entrainment of slow waves. Another 20 W/W^v mice and their controls equipped with a duodenal catheter and one pair of intestinal electrodes were used to test small intestinal transit represented by the geometric center (GC). Results were as follows. (1) The effect of pacing on slow wave frequency was sustained only in controls, and not in W/W^v mice. (2) Both gastric and intestinal slow waves were completely entrained in controls and W/W^v mice. Higher energy was required for pacing the stomach than the small intestine. (3) There was no significant difference in small intestinal transit between the controls and the W/W^v mice (GC: 5.4 vs. 5.5). (4) Pacing showed no effects on small intestinal transit in either wild-type (GC: 5.4 vs. 5.6) or W/W^v mice (GC: 5.5 vs. 5.7). We conclude that myenteric ICCs may not play an important role in the regulation of small intestinal transit in conscious mice. Gastric and intestinal pacing can be achieved without ICCs.