CFTR-like chloride channels in non-ciliated bronchiolar epithelial (Clara) cells.
Distal airways are believed to be a major site of disease in cystic fibrosis. The product of the CF gene, CFTR, is expressed in non-ciliated bronchiolar epithelial (Clara) cells. Clara cells in primary culture are capable of Cl- secretion which can be stimulated by cAMP and extracellular nucleotides. We used the patch clamp technique to look for Cl- channels in the apical membrane of rabbit Clara cells. In cell-attached patches, we recorded Cl- channels with a conductance for outward currents of 7.5 +/- 0.4 pS (n = 10) and for inward currents of 3.2 +/- 0.5 pS (n = 10); these channels typically exhibited slow kinetics and were not inhibited by the Cl- channel blockers NPPB and DIDS. Channel activity was not noticeably dependent on pipette potential. Addition of chlorophenylthio-cyclic AMP (cpt-cAMP) to the bath increased the percentage of cell-attached patches with active channels (33.8% vs 56.7%; p< 0.05) and the channel open probability (0.49 +/- 0.03 vs 0.84 +/- 0.02; p< 0.05). Extracellular ATP increased the percentage of cell-attached patches with active channels (28.7% to 50.0%; p< 0.05) but had no significant effect on the channel open probability (0.62 +/- 0.07 vs 0.60 +/- 0.06). In conclusion, rabbit non-ciliated bronchiolar epithelial cells express low-conductance Cl- channels that share many similarities with the CFTR-related Cl- channel and are regulated by cAMP and extracellular ATP.
Chinet
T C
TC
University of Paris, Boulogne, France.
Gabriel
S E
SE
Penland
C M
CM
Sato
M
M
Stutts
M J
MJ
Boucher
R C
RC
Van Scott
M R
MR
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001980:Bronchi / Q000502:physiology*; D002462:Cell Membrane / Q000502:physiology; D002478:Cells, Cultured; D018118:Chloride Channels / Q000502:physiology*; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000187:drug effects / Q000502:physiology*; D004553:Electric Conductivity; D004848:Epithelium / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects; D009579:Nitrobenzoates / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D011817:Rabbits; D013873:Thionucleotides / Q000494:pharmacology
D018118:Chloride Channels; D009579:Nitrobenzoates; D013873:Thionucleotides; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; C015929:8-((4-chlorophenyl)thio)cyclic-3',5'-AMP; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid