抄録
Evidence now being accumulated suggests that a subpopulation of interstitial cells in the myenteric plexus generates basal pacemaker electrical activity in the gut, including the ileum. These special pacemaker cells are referred to as interstitial cells of Cajal (ICC) from the histological resemblanceones. In this study, we employed an 8x8 MEA (with 150 μm in interpolar distance) to perform a spatio-temporal analysis of electrical activities in the ileal smooth muscle of BALB/c and W/WV mice lacking myenteric ICC. Smooth muscle layer containing the myenteric plexus was isolated from the ileum, and mounted in a recording chamber. To differentiate ICC pacemaker electrical activity from smooth muscle and neural activities, dihydropyridine (DHP) Ca2+ antagonists and TTX were added to the medium. Field potentials were recorded after high-pass filtering at 0.1 Hz. In analyses, digital band pass filter (0.05-0.6Hz) was applied. In normal (BALB/c) mice, field potentials of several tens of μV were observed over the recording area, whereas in W/WV mice the amplitude was much smaller and the occurrence was irregular. In power spectrum analysis, only normal mice showed a prominent peak corresponding to the ICC pacemaking frequency. Furthermore, potential mapping clearly demonstrated that ileal smooth muscle from normal mice generates propagating spontaneous electrical potentials, but that from W/WV mice does not. These results suggest that network-forming ICC in the myenteric plexus play a crucial role in coordinating electrical activities of the ileum as well as generating pacemaker potentials. [J Physiol Sci. 2008;58 Suppl:S55]
