title: Mibefradil-sensitive component involved in the plateau potential in submucosal interstitial cells of the murine proximal colon.
abstract: Submucosal interstitial cells of Cajal (ICC(SM)) produce plateau potentials comprised of initial fast and subsequent plateau components. The possible involvement of voltage-dependent Ca(2+) channels in plateau potentials was examined in ICC(SM) of the murine proximal colon. Increases in external K(+) concentration ([K(+)](o)) changed the rise rate of the initial component in a biphasic way, an increase in 10.6 or 15.3mM [K(+)](o) and a decrease in 20.0mM [K(+)](o). The rise rate of plateau potentials was significantly reduced by the application of 3 microM mibefradil or 100 microM Ni(2+) but not by 0.3 microM nifedipine. The inhibitory effect of mibefradil on the rise rate of plateau potentials was concentration-dependent with an IC(50) value of 1.0 microM. In conclusion, the initial phase of plateau potentials is partly due to the activation of T-type Ca(2+) channel in ICC(SM) from the murine proximal colon.
authors.affiliation: Department of Regulatory Cell Physiology, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan. ayahotta@med.nagoya-cu.ac.jp
authors.forename: Aya
authors.initials: A
authors.lastname: Hotta
authors.forename: Noriko
authors.initials: N
authors.lastname: Okada
authors.forename: Hikaru
authors.initials: H
authors.lastname: Suzuki
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000008:administration & dosage; D002478:Cells, Cultured; D003106:Colon / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D007413:Intestinal Mucosa / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology*; D020748:Mibefradil / Q000008:administration & dosage*; D051379:Mice; D008807:Mice, Inbred BALB C; D013368:Submucous Plexus / Q000187:drug effects / Q000502:physiology*
chemical_list: D002121:Calcium Channel Blockers; D020748:Mibefradil