Non-selective cation and dysfunctional chloride channels in the apical membrane of nasal epithelial cells cultured from cystic fibrosis patients.
Chloride channels and non-selective cation channels in the apical membranes of cultured nasal epithelial cells from three cystic fibrosis patients were investigated with the patch-clamp technique. Outwardly rectifying chloride channels were found in 31% of the inside-out patches, but activity of this channel was never observed in cell-attached patches, even after stimulation with adrenaline. In 30% of the patches with chloride channels, activation occurred immediately after excision. Most of the channels, however, activated only after a membrane depolarization of +40 to +120 mV. Once activated, the chloride channels were indistinguishable from those in nasal epithelial cells of control patients. Amiloride-insensitive, calcium- and voltage-dependent, non-selective cation channels were present in 11% of the cell-attached and 43% of the cell-free patches and could not be distinguished from those in controls. The cystic fibrosis chloride channel defect is conserved in cultured nasal epithelial cells, while a non-selective cation channel is apparently not affected.
Jorissen
M
M
Center for Human Genetics, University of Leuven, Belgium.
Vereecke
J
J
Carmeliet
E
E
Van den Berghe
H
H
Cassiman
J J
JJ
D000293:Adolescent; D000328:Adult; D000584:Amiloride / Q000378:metabolism; D001693:Biological Transport, Active; D002412:Cations / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002648:Child; D018118:Chloride Channels; D003550:Cystic Fibrosis / Q000378:metabolism*; D004848:Epithelium / Q000378:metabolism; D006801:Humans; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000378:metabolism*; D009296:Nasal Cavity / Q000378:metabolism*
D002412:Cations; D018118:Chloride Channels; D008565:Membrane Proteins; D000584:Amiloride