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Zinc activates KCNQ1 and KCNN4 K + channels in T84 secretory epithelial cells
Author(s) -
Mongiardo Krystin M,
Crane John K,
Duffey Michael E
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.913.28
Subject(s) - dithiothreitol , chemistry , intracellular , secretion , reagent , zinc , apical membrane , epithelial polarity , membrane potential , biophysics , membrane , biochemistry , biology , organic chemistry , enzyme
Basolateral membrane K + channels establish the electrical driving force for anion secretion by epithelial tissues. We determined the effects of Zn 2+ , an inhibitor of anion secretion, on these channels in T84 human colonic epithelial cells. After Cl − secretion was stimulated in monolayers by chlorophenylthio‐cAMP (50 μM), serosal Zn 2+ (2mM, zinc acetate) rapidly increased the short circuit current (Isc) from 32±5 to 93±8 μA/cm 2 , followed by inhibition to 17.1±3.2 (n=6). To determine the mechanisms of activation, tissues were pretreated with the KCNQ1 inhibitor 293B (100 μM) in the serosal solution, which reduced the Zn 2+ ‐activated Isc by 57%. The KCNN4 inhibitor TRAM‐34 (10 μM) reduced activation by 76%. Thus, Zn 2+ activated both KCNQ1 and KCNN4 K + channels. Activation of K + current by Zn 2+ was seen in isolated voltage‐clamped cells (233±103 pA, n=4). Fura‐2 fluorescence ratio measurements in isolated cells showed Zn 2+ caused a slow rise in Ca 2+ which was blocked by the intracellular Zn 2+ chelator, pyridylmethylethylenediamine (TPEN), suggesting that Zn 2+ can act on intracellular sites. Since Zn 2+ can modify disulfide bonds, we exposed T84 monolayers to the thiol reagent, dithiothreitol (DTT, 5mM), and like Zn 2+ , DTT transiently stimulated Isc (43±4 to 82±2 μA/cm 2 , n=3). These results suggest Zn 2+ activates basolateral membrane K + channels, probably via effects on disulfide bonds. (Supported by NIH AI 181528)