title: Novel effects of minocycline on Ca(2+)-dependent Cl(-) secretion in human airway epithelial Calu-3 cells.
abstract: The present study concerns previously unreported effects of the antibiotic minocycline on the transepithelial Cl(-) transport in Calu-3 cells, which display electrophysiological properties consistent with human airway serous cells. Basolateral 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS, 200 microM) augmented Cl(-) secretion, which was detected as a 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB, 100 microM, a Cl(-) channel blocker)-sensitive short-circuit current (I(sc)). The DIDS-induced I(sc) was composed of Ca(2+)-activated K(+) (K(Ca)) channel-dependent and -independent components. The former was selectively inhibited by 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetra(acetoxymethyl)ester (BAPTA/AM, 10 microM), charybdotoxin (ChTx, 100 nM), clotrimazole (10 microM), basolateral Ca(2+) removal, and basolateral minocycline (IC(50) = 20 microM). The latter was attenuated by basolateral BaCl (5 mM). In contrast, forskolin (10 microM)-induced I(sc), which is insensitive to BAPTA/AM and ChTx, was unaffected by minocycline (100 microM). ATP-induced I(sc) was partially inhibited by basolateral but not by apical minocycline. I(sc) due to basolateral application of ionomycin (1 microM) was markedly suppressed by NPPB and basolateral Ca(2+) removal. These inhibitory effects were mimicked by minocycline applied only from the basolateral side of the monolayer. In the basolateral absence of Ca(2+), 1-ethyl-2-benzimdazolinone (500 microM), a K(Ca) channel opener, generated a sustained I(sc) sensitive to ChTx. Minocycline had no significant effect on the ChTx-sensitive component of the I(sc). It is concluded that minocycline inhibits K(Ca) channel-dependent Cl(-) secretion via a blockade of Ca(2+) influx across the basolateral membrane from the extracellular side.
authors.affiliation: Second Division, Second Department of Internal Medicine, School of Medicine, Nagoya University, Tsurumai-cho, Nagoya, 466-8550, Japan. itoyasu@med.nagoya-u.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Ito
authors.forename: M
authors.initials: M
authors.lastname: Son
authors.forename: H
authors.initials: H
authors.lastname: Kume
authors.forename: K
authors.initials: K
authors.lastname: Yamaki
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002118:Calcium / Q000502:physiology*; D002460:Cell Line; D002614:Chelating Agents / Q000494:pharmacology; D018118:Chloride Channels / Q000187:drug effects / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism*; D005576:Colforsin / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D015759:Ionomycin / Q000494:pharmacology; D007700:Kinetics; D008911:Minocycline / Q000494:pharmacology*; D026902:Potassium Channel Blockers / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D002614:Chelating Agents; D018118:Chloride Channels; D002712:Chlorides; D026902:Potassium Channel Blockers; D005576:Colforsin; D004533:Egtazic Acid; D015759:Ionomycin; D008911:Minocycline; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D002118:Calcium