K+ waves in brain cortex visualized using a long-wavelength K+-sensing fluorescent indicator

Nat Methods. 2005 Nov;2(11):825-7. doi: 10.1038/nmeth801.

Abstract

We synthesized a water-soluble, long-wavelength K(+) sensor, TAC-Red, consisting of triazacryptand coupled to 3,6-bis(dimethylamino)xanthylium, whose fluorescence increased 14-fold at 0-50 mM K(+) with K(+)-to-Na(+) selectivity >30. We visualized K(+) waves in TAC-Red-stained brain cortex in mice during spreading depression, with velocity 4.4 +/- 0.5 mm/min, and K(+) release and reuptake half-times (t(1/2)) of 12 +/- 2 and 32 +/- 4 s, respectively. Aquaporin-4 (AQP4) deletion slowed K(+) reuptake about twofold, suggesting AQP4-dependent K(+) uptake by astroglia.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Aquaporin 4 / genetics
  • Aquaporin 4 / metabolism
  • Astrocytes / metabolism
  • Aza Compounds / analysis
  • Aza Compounds / chemistry
  • Cerebral Cortex / metabolism*
  • Fluorescent Dyes / analysis*
  • Fluorescent Dyes / chemistry
  • Heterocyclic Compounds, 3-Ring / analysis
  • Heterocyclic Compounds, 3-Ring / chemistry
  • Mice
  • Mice, Knockout
  • Molecular Structure
  • Potassium / analysis*
  • Potassium / metabolism
  • Solubility
  • Time Factors

Substances

  • Aqp4 protein, mouse
  • Aquaporin 4
  • Aza Compounds
  • Fluorescent Dyes
  • Heterocyclic Compounds, 3-Ring
  • TAC-Red
  • Potassium