Two types of chloride channels in hen colon epithelial cells identified by patch-clamp experiments |
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Authors: | Horst Fischer Wolfgang Kromer Wolfgang Clauss |
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Institution: | (1) Institut für Veterinärphysiologie Freie Universität Berlin, Koserstr. 20, W-1000 Berlin 33, Federal Republic of Germany;(2) Byk Gulden Lomberg GmbH, W-7750 Konstanz, Federal Republic of Germany |
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Abstract: | Summary Freshly isolated epithelial cells from hen colon were investigated using the patch-clamp technique. The aim of this investigation was to characterise the cellular conducting site for Cl- secretion. In cell-attached mode two types of Cl--channels were found. Both showed distinct outward rectification. The channel types differed in single channel conductances and the marked voltage dependence of the open probabilities. A low conductance Cl--channel was observed with a mean conductance at negative holding potentials of g-=9 pS, and of g+=34 pS at positive potentials. This channel was predominantly open at negative potentials, corresponding to cell hyperpolarization. The second channel type observed had conductances of g-=35 pS and g+=77 pS, and showed increasing open probabilities with increasing holding potentials (cell depolarisation). Both channel types were blockable by the Cl--channel blocker NPPB. These data in combination with previously published transepithelial transport data on hen colon indicate that these channels are the Cl- secretory sites in colon epithelium.Abbreviations DNSO
dimethylsulfoxide
- EGTA
ethyleneglycol triacetic acid
- g+, g-
single channel conductance at positive and negative voltages
- HEPES
N-(2-hydroxy-ethyl)piperazine-N-(2-ethane-sulfonic acid)
- i
single channel current
- NMDG
N-methyl-d-glucosamine
- NPPB
5-hitro-2-(3-phenylpropylamino)-benzoate
- Po
open probability
- Vp
holding potential |
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Keywords: | Epithelium Patch clamp Cell-attached mode NPPB Cl- secretion |
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