Jens Georg Leipziger

The essential role of luminal BK channels in distal colonic K+ secretion

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  • Mads V Sörensen, Department of Physiology and Biophysics, Aarhus University, Aarhus, Denmark.
  • ,
  • Jens Leipziger

Distal colonic K(+) excretion is determined by the balance of K(+) absorption and K(+) secretion of the enterocytes. K(+) secretion occurs via active basolateral K(+) uptake mostly via the NKCC1 co-transporter followed by K(+) exit via a luminal K(+) channel. The specific focus here is directed towards the luminal secretory K(+) channel (1). Several recent observations highlight the pivotal role of the large conductance, Ca(2+)-activated K(Ca)1.1 (BK, KCNMA) channel as the only functionally relevant luminal K(+) efflux pathway in mouse distal colon (2, 3). This conclusion was based on defining results from BK knock-out mice. The following key observations were made: 1. BK channels mediate the resting distal colonic K(+) secretion (2, 4), 2. They are acutely stimulated by activation of luminal nucleotide receptor and elevations of intracellular Ca(2+) (2, 4, 5), 3. Colonic BK channels are up-regulated by increases of plasma aldosterone (3), 4. In addition, the cAMP-stimulated distal colonic K(+) secretion is apparently mediated via BK channels, 5. Finally, aldosterone was found to up-regulate specifically the ZERO (e.g. cAMP activated) C-terminal splice variant of the BK channel. In summary, we suggest that the sole exit pathway for transcellular (K+) secretion in mammalian distal colon is the BK channel, which is the target for short term intracellular Ca(2+) and cAMP activation and long term aldosterone regulation.

Original languageEnglish
JournalJournal of Clinical Investigation
Volume56 Suppl
Pages (from-to)301
Publication statusPublished - 2009

    Research areas

  • Aldosterone, Animals, Calcium, Colon, Cyclic AMP, Enterocytes, Large-Conductance Calcium-Activated Potassium Channel alpha Subunits, Large-Conductance Calcium-Activated Potassium Channels, Mice, Mice, Knockout, Potassium, Journal Article

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