title: Dual pathway activated by tert-butyl hydroperoxide in human airway anion secretion.
abstract: We analyzed the mechanisms underlying the ion transport induced by tert-butyl hydroperoxide (t-BOOH), a membrane-permeant oxidant that has been widely used as a model of oxidative stress, in human airway epithelial cells (Calu-3). We found that t-BOOH induced a short-circuit current that was composed of two distinct components, a peaked component (PC) and a sustained component (SC). Both components were reduced by the presence of H-89 (N-[2-(4-bromocinnamylamino)ethyl]-5-isoquinoline) [10 microM, a protein kinase A (PKA) inhibitor] and clofilium (100 microM, a cAMP-dependent K+ channel inhibitor) but not by charybdotoxin (50 nM, a human intermediate conductance Ca2+-activated K+ channel inhibitor), suggesting that both PC and SC were generated through a common PKA-dependent/Ca2+-independent pathway. Notwithstanding, analyses of the physiological properties revealed that PC and SC were attributable to different pathways. PC, but not SC, was correlated with apical membrane Cl- conductance and was inhibited by the cyclooxygenase (COX)-2 inhibitor NS-398 (N-[2-(cyclohexyloxyl)-4-nitrophenyl]-methane sulfonamide; 10 microM). In contrast, SC, but not PC, was composed of a component sensitive to bumetanide (50 microM), an inhibitor of the basolateral Na+-K+-2Cl- cotransporter (NKCC1), and was abolished by the cytoskeleton dysfunction induced by cytochalasin D (10 microM) and (R)-(+)-trans-N-(4-pyridyl)-4-(1-aminoethyl)-cyclohexane carboxamide (Y-27632; 20 microM). Collectively, t-BOOH induces PKA-related anion secretion through two independent pathways: rapid activation of apical anion efflux through a COX-2-dependent/cytoskeleton-independent pathway and relatively delayed activation of NKCC1 for basolateral anion uptake through a COX-2-independent/cytoskeleton-dependent pathway.
authors.affiliation: Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan. itoyasu@med.nagoya-u.ac.jp.
authors.forename: Tadakatsu
authors.initials: T
authors.lastname: Matsuno
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Ito
authors.forename: Takamasa
authors.initials: T
authors.lastname: Ohashi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Morise
authors.forename: Naoya
authors.initials: N
authors.lastname: Takeda
authors.forename: Kaoru
authors.initials: K
authors.lastname: Shimokata
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Imaizumi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kume
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Hasegawa
mesh_terms: D000577:Amides / Q000494:pharmacology; D001639:Bicarbonates / Q000378:metabolism*; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism*; D000242:Cyclic AMP / Q000502:physiology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000502:physiology; D003599:Cytoskeleton / Q000502:physiology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008168:Lung / Q000187:drug effects / Q000378:metabolism*; D018384:Oxidative Stress; D011725:Pyridines / Q000494:pharmacology; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D028021:Sodium-Potassium-Chloride Symporters / Q000502:physiology; D064506:Solute Carrier Family 12, Member 2; D020122:tert-Butylhydroperoxide / Q000494:pharmacology*
chemical_list: D000577:Amides; D001639:Bicarbonates; C505032:CFTR protein, human; D002712:Chlorides; D016861:Cyclooxygenase Inhibitors; D011725:Pyridines; D000644:Quaternary Ammonium Compounds; C578877:SLC12A2 protein, human; D028021:Sodium-Potassium-Chloride Symporters; D064506:Solute Carrier Family 12, Member 2; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; C108830:Y 27632; C022799:clofilium; D020122:tert-Butylhydroperoxide; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases