Outward-rectifying chloride channels in cultured adult and fetal human nasal epithelial cells.
The patch-clamp technique was used to characterize ion channels in the apical membranes of cultured human nasal epithelial cells, dissociated from fetal nasal mucosa and from adult nasal polyps. Outward-rectifying chloride channels were found in 4.3% of the cell-attached patches from fetal cells (n = 258) and in 3.1% of the patches from adult cells (n = 320). After excision the number of patches containing active chloride channels increased threefold to 13% of the patches from the fetal cells and 10% from adult cells. The single-channel conductance at 0 mV in symmetrical 150 mM NaCl solutions was 24.3 +/- 0.9 pS (n = 28) and 26.0 +/- 1.2 pS (n = 30), respectively, in adult and fetal cells and showed outward rectification in the potential range from -80 to +80 mV. In fetal cells as well as in adult cells the channels were anion selective, and were almost impermeable for larger anions and monovalent cations. In cell-free patches the channels were Ca2+ independent. In most of the channels the open probability was voltage independent and high (+/- 0.86); in 20% of the channels, however, the open probability increased with depolarization. In conclusion, fetal nasal epithelial cells contain chloride channels in their apical membranes with single-channel properties and regulatory mechanisms similar to those found in cells from adults.
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
D002478:Cells, Cultured; D018118:Chloride Channels; D002712:Chlorides / Q000378:metabolism*; D004553:Electric Conductivity; D004847:Epithelial Cells; D004848:Epithelium / Q000378:metabolism; D006801:Humans; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000378:metabolism*; D009297:Nasal Mucosa / Q000166:cytology / Q000196:embryology / Q000378:metabolism*
D018118:Chloride Channels; D002712:Chlorides; D008565:Membrane Proteins