title: Reconstitution of a calcium-activated potassium channel in basolateral membranes of rabbit colonocytes into planar lipid bilayers.
abstract: A highly enriched preparation of basolateral membrane vesicles was isolated from rabbit distal colon surface epithelial cells employing the method described by Wiener, Turnheim and van Os (Weiner, H., Turnheim, K., van Os, C.H. (1989) J. Membrane Biol. 110:147-162) and incorporated into planar lipid bilayers. With very few exceptions, the channel activity observed was that of a high conductance. Ca2+-activated K+ channel. This channel is highly selective for K+ over Na+ and Cl-, displays voltage-gating similar to "maxi" K(Ca) channels found in other cell membranes, and kinetic analyses are consistent with the notion that K+ diffusion through the channel involves either the binding of a single K+ ion to a site within the channel or "single-filing" ("multi-ion occupancy"). Channel activity is inhibited by the venom from the scorpion Leiurus quinquestriatus, Ba2+, quinine, and trifluoperazine. The possible role of this channel in the function of these cells is discussed.
authors.affiliation: Department of Physiology and Cell Biology, University of Texas Medical School, Houston 77225.
authors.forename: K
authors.initials: K
authors.lastname: Turnheim
authors.forename: J
authors.initials: J
authors.lastname: Costantin
authors.forename: S
authors.initials: S
authors.lastname: Chan
authors.forename: S G
authors.initials: SG
authors.lastname: Schultz
mesh_terms: D000703:Analog-Digital Conversion; D000818:Animals; D001464:Barium / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D003106:Colon / Q000166:cytology / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008051:Lipid Bilayers; D008564:Membrane Potentials; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D011803:Quinine / Q000494:pharmacology; D011817:Rabbits; D012604:Scorpion Venoms; D014268:Trifluoperazine / Q000494:pharmacology
chemical_list: D008051:Lipid Bilayers; D015221:Potassium Channels; D012604:Scorpion Venoms; D014268:Trifluoperazine; D001464:Barium; D011803:Quinine; D002118:Calcium