title: Characterization and comparison of ion transport across sheep and human airway epithelium.
abstract: This study aimed to assess the suitability of sheep tracheal epithelium as a model for studies of human airway ion transport. Ovine and human airway epithelium were mounted in Ussing chambers under short circuit conditions. Bumetanide (100 microM) reduced short-circuit current (Isc) by a mean of 21.3% +/- SEM 2.0, n = 8, in sheep, and 30.4% +/- 9.7, n = 3, in human airway epithelium. Acetazolamide (100 microM) decreased Isc by 10.6% +/- 1.2, n = 18, in sheep, and 5.8% +/- 2.9, n = 3, in human airways. Phloridzin (200 microM) reduced Isc by 4.7% +/- 0.8, n = 7, and 3.1% +/- 5.1, n = 3 in sheep and human tissue respectively. Amiloride (100 microM) decreased Isc by 42.9% +/- 3.5, n = 12, in sheep airways, whilst bathing the mucosal surface with Na(+)-free solutions reduced Isc by 67.4% +/- 4.2, n = 18. The sequential addition of acetazolamide, bumetanide, phloridzin, amiloride and mucosal Na(+)-free solutions totally inhibited the basal Isc in both sheep and human tissues, suggesting that Cl- and HCO3- secretion, Na(+)-glucose co-transport and amiloride-sensitive and -insensitive Na+ absorption contribute to the Isc. The similarities between the species suggest that sheep tracheal epithelium is a useful model for basal studies of airway ion transport, and may prove a valuable tool for further regulatory studies.
authors.affiliation: Ion Transport Laboratory, National Heart and Lung Institute, London, UK.
authors.forename: D M
authors.initials: DM
authors.lastname: Steel
authors.forename: A
authors.initials: A
authors.lastname: Graham
authors.forename: D M
authors.initials: DM
authors.lastname: Geddes
authors.forename: E W
authors.initials: EW
authors.lastname: Alton
mesh_terms: D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000494:pharmacology; D000086:Acetazolamide / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001980:Bronchi / Q000187:drug effects / Q000378:metabolism*; D002034:Bumetanide / Q000494:pharmacology; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D017136:Ion Transport / Q000187:drug effects; D010042:Ouabain / Q000494:pharmacology; D010695:Phlorhizin / Q000494:pharmacology; D012756:Sheep / Q000378:metabolism*; D014132:Trachea / Q000187:drug effects / Q000378:metabolism*
chemical_list: D002034:Bumetanide; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D010042:Ouabain; D000584:Amiloride; D010695:Phlorhizin; D000086:Acetazolamide; C039614:ethylisopropylamiloride