A Ba2+-resistant, acid-sensitive K+ conductance in Na+-absorbing H441 human airway epithelial cells

Sarah K. Inglis, Sean G. Brown, Maree J. Constable, Niall McTavish, Richard E. Olver, Stuart M. Wilson

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    By analysis of whole cell membrane currents in Na+-absorbing H441 human airway epithelial cells, we have identified a K+ conductance (GK) resistant to Ba2+ but sensitive to bupivacaine or extracellular acidification. In polarized H441 monolayers, we have demonstrated that bupivacaine, lidocaine, and quinidine inhibit basolateral membrane K+ current (IBl) whereas Ba2+ has only a weak inhibitory effect. IBl was also inhibited by basolateral acidification, and, although subsequent addition of bupivacaine caused a further fall in IBl, acidification had no effect after bupivacaine, demonstrating that cells grown under these conditions express at least two different bupivacaine-sensitive K+ channels, only one of which is acid sensitive. Basolateral acidification also inhibited short-circuit current (ISC), and basolateral bupivacaine, lidocaine, quinidine, and Ba2+ inhibited ISC at concentrations similar to those needed to inhibit IBl, suggesting that the K+ channels underlying IBl are part of the absorptive mechanism. Analyses using RT-PCR showed that mRNA encoding several two-pore domain K+ (K2P) channels was detected in cells grown under standard conditions (TWIK-1, TREK-1, TASK-2, TWIK-2, KCNK-7, TASK-3, TREK-2, THIK-1, and TALK-2). We therefore suggest that K2P channels underlie GK in unstimulated cells and so maintain the driving force for Na+ absorption. Since this ion transport process is vital to lung function, K2P channels thus play an important but previously undocumented role in pulmonary physiology.
    Original languageEnglish
    Pages (from-to)L1304-L1312
    JournalAmerican Journal of Physiology: Lung Cellular and Molecular Physiology
    Issue number5
    Publication statusPublished - May 2007


    • Airway sodium channel transport
    • Patch clamp
    • Ussing chambers


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