ANG-2 for quantitative Na(+) determination in living cells by time-resolved fluorescence microscopy

Photochem Photobiol Sci. 2014 Dec;13(12):1699-710. doi: 10.1039/c4pp00061g. Epub 2014 Oct 14.


Sodium ions (Na(+)) play an important role in a plethora of cellular processes, which are complex and partly still unexplored. For the investigation of these processes and quantification of intracellular Na(+) concentrations ([Na(+)]i), two-photon coupled fluorescence lifetime imaging microscopy (2P-FLIM) was performed in the salivary glands of the cockroach Periplaneta americana. For this, the novel Na(+)-sensitive fluorescent dye Asante NaTRIUM Green-2 (ANG-2) was evaluated, both in vitro and in situ. In this context, absorption coefficients, fluorescence quantum yields and 2P action cross-sections were determined for the first time. ANG-2 was 2P-excitable over a broad spectral range and displayed fluorescence in the visible spectral range. Although the fluorescence decay behaviour of ANG-2 was triexponential in vitro, its analysis indicates a Na(+)-sensitivity appropriate for recordings in living cells. The Na(+)-sensitivity was reduced in situ, but the biexponential fluorescence decay behaviour could be successfully analysed in terms of quantitative [Na(+)]i recordings. Thus, physiological 2P-FLIM measurements revealed a dopamine-induced [Na(+)]i rise in cockroach salivary gland cells, which was dependent on a Na(+)-K(+)-2Cl(-) cotransporter (NKCC) activity. It was concluded that ANG-2 is a promising new sodium indicator applicable for diverse biological systems.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acinar Cells / drug effects
  • Acinar Cells / metabolism
  • Animals
  • Bumetanide / pharmacology
  • Cockroaches
  • Dopamine / metabolism
  • Fluorescence
  • Fluorescent Dyes* / chemistry
  • Insect Proteins / metabolism
  • Intracellular Space / metabolism*
  • Ions / metabolism*
  • Microscopy, Fluorescence / methods*
  • Molecular Structure
  • Salivary Glands / drug effects
  • Salivary Glands / metabolism
  • Sodium / metabolism*
  • Sodium Potassium Chloride Symporter Inhibitors / pharmacology
  • Solute Carrier Family 12, Member 2 / metabolism


  • Fluorescent Dyes
  • Insect Proteins
  • Ions
  • Sodium Potassium Chloride Symporter Inhibitors
  • Solute Carrier Family 12, Member 2
  • Bumetanide
  • Sodium
  • Dopamine