@article{RoderHille2014,
  author    = {Roder, Phillip and Hille, Carsten},
  title     = {ANG-2 for quantitative Na+ determination in living cells by time-resolved fluorescence microscopy},
  series = {Photochemical \& photobiological sciences},
  volume    = {13},
  journal   = {Photochemical \& photobiological sciences},
  number    = {12},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1474-905X},
  doi       = {10.1039/c4pp00061g},
  pages     = {1699 -- 1710},
  year      = {2014},
  abstract  = {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.},
  language  = {en}
}