Gut motility-basic research and disease

Abstract

We investigated the spontaneous electrical and mechanical activities in the ileum of W/W^v mutant mice, in which ICC at myenteric region (ICC-MY) is deficient but ICC at deep muscular region (ICC-DMP) is present. In the isolated 1-cm long segment, electrical slow waves (SW) and action potentials (AP), the force generated in the muscle in the longitudinal direction and the intraluminal pressure was recorded simultaneously. In +/+ mice, rhythmic circular and longitudinal muscle activities were synchronously recorded. SW and AP were also recorded associated with mechanical activities. In W/W^v mice, SW could not be recorded, but irregular mechanical activities associated with AP could be recorded. Tetrodotoxin (TTX) or L-NAME significantly decreased the interval of the longitudinal muscle contractions and increased their regularity. These results suggested that the strong suppression mediated by ICC-DMP and enteric motor nerves on the autonomic rhythmicity was working in the mouse ileum in the absence of ICC-MY. To reveal the contribution of ICC-DMP and enteric motor nerves to changes in gut spontaneous motility in experimental colitis, electrical and mechanical activities were recorded simultaneously in the isolated ileum. Colitis was induced by the provision of dextran sodium sulfate (DSS: m.w. 40,000) in the drinking water at a concentration of 3% for 7 days in +/+ and W/W^v mutant mice. The changes in frequency, regularity and patterns of spontaneous motilities were compared between +/+ and W/W^vmutant mice. The effects of L-NAME, hexamethonium and TTX were also compared. [Jpn J Physiol 54 Suppl:S59 (2004)]