抄録
Recent studies have suggested that as in sino-atria node cells in the heart, specialised pacemaker cells exist in the gastro-intestinal wall, and drive smooth muscle cells to achieve their functions. The pacemaker cells are characterised as interstitial cells of Cajal (ICC) from their immuno-histochemical features. Calcium release from InsP3R is known to contribute to many important cellular functions, including generation of spontaneous rhythmicity in gastrointestinal motility. There are several reports of InsP3R inhibitors significantly suppressing or terminating spontaneous electrical activity in the gastrointestinal tract. Suzuki et al. (1) have demonstrated that spontaneous electrical activity is not observed in stomach smooth muscle tissue of mice lacking type 1 InsP3R. Using cell cluster preparation and RT-PCR, here we show this InsP3R co-ordinate with RyR to generate ICC pacemaker Ca2+ activity underlying spontaneous electrical activity in the gut (2-4). We also talk about some modulating mechanisms via purinoceptors (5). (1) Suzuki, H. et al. (2000) J. Physiol. 525, 105-111. (2)Aoyama, M. et al. (2004). J. Cell. Sci. 117, 2813-2825. (3) Liu, H.-N., et al. (2005). J. Biol. Rhythm. 20, 15-26. (4) Liu, H.-N., et al. (2005). Biochem. Biophys. Res. Commun. 328, 640-646. (5) Furuzono, S. et al. (2005). Neuropharmacol. 48, 264-273. [Jpn J Physiol 55 Suppl:S24 (2005)]
