Reconstitution of a calcium-activated potassium channel in basolateral membranes of rabbit colonocytes into planar lipid bilayers |
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Authors: | K Turnheim J Costantin S Chan S G Schultz |
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Institution: | (1) Department of Physiology and Cell Biology, University of Texas Medical School, 77225 Houston, Texas;(2) Present address: Pharmakologisches Institut der Universitat Wien, Wahringer Strasse 13a, A-1090 Wien, Austria |
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Abstract: | Summary 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-filling ( multi-ion occupancy ). Channel activity is inhibited by the venom from the scorpionLeiurus quinquestriatus, Ba2+, quinine, and trifluoperazine. The possible role of this channel in the function of these cells is discussed. |
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Keywords: | Ca2+-activated K+ channels rabbit colon basolateral membranes Ba2+ quinine scorpion venom trifluoperazine lipid bilayers reconstitution |
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