title: Oxidant stress stimulates Ca2+-activated chloride channels in the apical activated membrane of cultured nonciliated human nasal epithelial cells.
abstract: Respiratory tissues can be damaged by the exposure of airway epithelial cells to reactive oxygen species that generate oxidative stress. We studied the effects of the hydroxyl radical *OH, for which there is no natural intra- or extracellular scavenger, on a Ca(2+)-activated chloride channel (CACC) that participates in Cl(-) secretion in the apical membrane of airway epithelial cells. We identified and characterized CACC in cell-attached and in inside-out excised membrane patches from the apical membrane of cultured nonciliated human nasal epithelial cells. In these cells, the CACC was outwardly rectified, Ca(2+)/calmodulin-kinase II, and voltage dependent. The channel was activated in cell-attached and inside-out patches in a bath solution containing millimolar [Ca(2+)] and ran down quickly. The channel was reversibly or irreversibly activated by exposure of the internal surface of the membrane to *OH, which depended on the concentration and the duration of exposure to H(2)O(2). CACC activity evoked by oxidative stress was inhibited by 1,3-dimethyl-2-thiurea, an antioxidant that scavenges hydroxyl radicals, and by the reduced form of glutathione. The oxidized SH residues could be close to the Ca(2+)/calmodulin kinase site. The reversible or irreversible activation of CACC after a period of oxidative stress without change in [Ca(2+)] is a new observation. CACC play a direct role in mucus production by goblet cells and may thus contribute to the pathogenesis of asthma.
authors.affiliation: Laboratoire de Cytophysiologie et Toxicologie Cellulaire, Université Paris, France. jeulin@paris7.jussieu.fr
authors.forename: Claudette
authors.initials: C
authors.lastname: Jeulin
authors.forename: Rina
authors.initials: R
authors.lastname: Guadagnini
authors.forename: Francelyne
authors.initials: F
authors.lastname: Marano
mesh_terms: D001249:Asthma / Q000378:metabolism / Q000503:physiopathology; D002118:Calcium / Q000378:metabolism; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D016764:Cell Polarity / Q000502:physiology; D002478:Cells, Cultured; D018118:Chloride Channels / Q000502:physiology*; D005576:Colforsin / Q000494:pharmacology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000502:physiology; D003593:Cytoplasm / Q000378:metabolism; D006801:Humans; D017665:Hydroxyl Radical / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009297:Nasal Mucosa / Q000166:cytology / Q000502:physiology*; D018384:Oxidative Stress / Q000502:physiology*; D018408:Patch-Clamp Techniques
chemical_list: C505032:CFTR protein, human; C492109:CLCA1 protein, human; D018118:Chloride Channels; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D005576:Colforsin; D017665:Hydroxyl Radical; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002118:Calcium