Abstract
It has been suggested that periodic rise of the intracellular Ca2+concentration ([Ca2+]i) is a primary mechanism in c-Kit-immunopositive interstitial cells (=ICC), and consequently generating pacemaker potentials through periodic activation of Ca2+-activated Cl− channels. We have recently developed a cultured cell cluster preparation from the small intestine of the mice. On the other hand, many important reports have dealt with spontaneous rhythmicity in stomach smooth muscle. Therefore, in this study, we prepared cell clusters from the stomach smooth muscle tissue of mice.
In the presence of nifedipine, pacemaker ([Ca2+]i)oscillations were observed limited regions with positive c-Kit-immunoreactivity. In the majority of cell cluster preparations with multiple regions of ([Ca2+]i)oscillations, ([Ca2+]i)oscillated synchronously in the same phase. A small number of cell clusters showed multiple regions of ([Ca2+]i)oscillation synchronised but with a considerable phase shift. Applications of either 2-APB or xestospongin C rather rapidly abolished the spontaneous ([Ca2+]i)oscillation, suggesting involvement of intracellular Ca2+release channels, especially inositol 1,4,5-trisphosphate receptor. [Jpn J Physiol 54 Suppl:S123 (2004)]
