Calcium influx mediated by the inwardly rectifying K+ channel Kir4.1 (KCNJ10) at low external K+ concentration

Cell Calcium. 2007 Sep;42(3):271-80. doi: 10.1016/j.ceca.2006.12.004. Epub 2007 Feb 5.


COS-1 cells with heterologeous expression of the Kir4.1 (KCNJ10) channel subunit, possess functional Kir4.1 channels and become capable to generating cytosolic Ca2+ transients, upon lowering of the extracellular K+ concentration to 2 mM or below. These Ca2+ transients are blocked by external Ba2+ (100 microM). Acute brain stem slices from wild-type mice (second post-natal week), which were loaded with the fluorescent Ca2+ indicator Oregon Green BAPTA-1-AM, were exposed to 0.2 mM K+. Under these conditions astrocytes, but not neurons, responded with cytosolic Ca2+ elevations in wild-type mice. This astrocyte-specific response has previously been used to identify astroglial cells type [R. Dallwig, H. Vitten, J.W. Deitmer, A novel barium-sensitive calcium influx into rat astrocytes at low external potassium. Cell Calcium 28 (2000) 247-259]. In Kir4.1 knock-out (Kir4.1-/-) mice, the number of responding cells was dramatically reduced and the Ca2+ transients in responding cells were significantly smaller than in wild-type mice. Our results indicate that Kir4.1 channels are the molecular substrate for the observed Ca2+ influx in astrocytes under conditions of low external K+-concentration.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aniline Compounds / metabolism
  • Animals
  • Astrocytes / cytology
  • Astrocytes / metabolism
  • COS Cells
  • Calcium / metabolism*
  • Chlorocebus aethiops
  • Fluoresceins / metabolism
  • Fluorescent Dyes / metabolism
  • Membrane Potentials
  • Mice
  • Mice, Knockout
  • Patch-Clamp Techniques
  • Potassium / metabolism*
  • Potassium Channels, Inwardly Rectifying / genetics
  • Potassium Channels, Inwardly Rectifying / metabolism*
  • Rats
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism


  • Aniline Compounds
  • Fluoresceins
  • Fluorescent Dyes
  • Kcnj10 (channel)
  • Oregon green 488 BAPTA-1
  • Potassium Channels, Inwardly Rectifying
  • Recombinant Fusion Proteins
  • Potassium
  • Calcium