title: NADPH oxidase-dependent acid production in airway epithelial cells.
abstract: The purpose of this study was to determine the role of NADPH oxidase in H(+) secretion by airway epithelia. In whole cell patch clamp recordings primary human tracheal epithelial cells (hTE) and the human serous gland cell line Calu-3 expressed a functionally similar zinc-blockable plasma membrane H(+) conductance. However, the rate of H(+) secretion of confluent epithelial monolayers measured in Ussing chambers was 9-fold larger in hTE compared with Calu-3. In hTE H(+) secretion was blocked by mucosal ZnCl(2) and the NADPH oxidase blockers acetovanillone and 4-(2-aminoethyl)benzenesulfonyl fluoride (AEBSF), whereas these same blockers had no effect in Calu-3. We determined levels of transcripts for the NADPH oxidase transmembrane isoforms (Nox1 through -5, Duox1 and -2, and p22(phox)) and found Duox1, -2, and p22(phox) to be highly expressed in hTE, as well as the intracellular subunits p40(phox), p47(phox), and p67(phox). In contrast, Calu-3 lacked transcripts for Duox1, p40(phox), and p47(phox). Anti-Duox antibody staining resulted in prominent apical staining in hTE but no significant staining in Calu-3. When treated with amiloride to block the Na(+)/H(+) exchanger, intracellular pH in hTE acidified at significantly higher rates than in Calu-3, and treatment with AEBSF blocked acidification. These data suggest a role for an apically located Duox-based NADPH oxidase during intracellular H(+) production and H(+) secretion, but not in H(+) conduction.
authors.affiliation: Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr. Way, Oakland, CA 94609, USA.
authors.forename: Christian
authors.initials: C
authors.lastname: Schwarzer
authors.forename: Terry E
authors.initials: TE
authors.lastname: Machen
authors.forename: Beate
authors.initials: B
authors.lastname: Illek
authors.forename: Horst
authors.initials: H
authors.lastname: Fischer
mesh_terms: D000098:Acetophenones / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002712:Chlorides / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D017931:DNA Primers / Q000737:chemistry; D000074623:Dual Oxidases; D004591:Electrophoresis, Polyacrylamide Gel; D004594:Electrophysiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology*; D005420:Flavoproteins / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008954:Models, Biological; D019255:NADPH Oxidases / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D016133:Polymerase Chain Reaction; D020033:Protein Isoforms; D011522:Protons; D012333:RNA, Messenger / Q000378:metabolism; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D013450:Sulfones / Q000494:pharmacology; D013997:Time Factors; D014132:Trachea / Q000166:cytology / Q000378:metabolism*; D015032:Zinc / Q000737:chemistry; D017967:Zinc Compounds / Q000494:pharmacology
chemical_list: D000098:Acetophenones; D002712:Chlorides; D017931:DNA Primers; D004791:Enzyme Inhibitors; D005420:Flavoproteins; D020033:Protein Isoforms; D011522:Protons; D012333:RNA, Messenger; D015842:Serine Proteinase Inhibitors; D013450:Sulfones; D017967:Zinc Compounds; C002010:4-(2-aminoethyl)benzenesulfonylfluoride; D000584:Amiloride; C016837:zinc chloride; C056165:acetovanillone; D000074623:Dual Oxidases; D019255:NADPH Oxidases; C431513:DUOX1 protein, human; D015032:Zinc