A K(+)-selective channel in the colonic carcinoma cell line: CaCo-2 is activated with membrane stretch.
CaCo-2 is a human colonic carcinoma cell line which becomes differentiated in culture to form a polarized epithelium exhibiting several of the functional characteristics of native colonic tissue. In the present study, CaCo-2 cells have been used for a patch-clamp study of colonic ion conductance pathways. A large, 120 pS K(+)-selective channel was found in cells forming subconfluent monolayers in culture. Unlike Maxi-K+ channels found in other epithelial cells, this channel was not activated with elevations in cytosolic Ca2+. Channel activity was stimulated with membrane depolarization and most markedly with membrane stretch. The application of negative pressure (20 mm-Hg) to both cell-attached and excised, inside-out membrane patches caused a burst of channel activity which disappeared within seconds of suction removal. Single-channel conductance of the pressure-activated channel was decreased when quinine (100 microM) was present in the patch pipette.
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Division of Cell Biology, Hospital for Sick Children, Toronto, Canada.
D002277:Carcinoma / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003110:Colonic Neoplasms / Q000378:metabolism*; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D011803:Quinine / Q000494:pharmacology
D015221:Potassium Channels; D011803:Quinine