Sodium Indicators

Molecular Probes sodium indicators allow spatial and temporal resolution of Na+ concentrations in the presence of physiological concentrations of other monovalent cations. These sodium indicators exhibit an increase in green fluorescence emission intensity upon binding Na+, with little shift in wavelength. 

Select sodium indicators

Indicators for Sodium

  • Measure steady-state changes in Na+ concentration
  • Track Na+ bursts in axons and presynaptic terminals

Indicators are available to estimate Na+ gradients in isolated mitochondria, to measure intracellular Na+ levels, to measure Na+ efflux in cells, and, in combination with other fluorescent indicators, to correlate changes in intracellular Na+ with Ca2+ and Mg2+ concentrations, intracellular pH, and membrane potential.

CA1 pyramidal neuron in a hippocampal slice filled with SBFI
CA1 pyramidal neuron in a hippocampal slice filled with SBFI delivered from a patch pipette.

Sodium Indicators Selection Guide

Used for spatial and temporal resolution of Na+ concentration and steady-state changes in sodium concentration, especially sodium/potassium ATPase studies. Also measures sodium bursts in axons and presynaptic terminals and axon initial segments.

  CoroNa Green, AM SBFI, Tetraammonium Salt SBFI, AM
Readout Increase in green fluorescence emission intensity upon binding Na+, with little shift in wavelength Spectral excitation shift used to estimate Na+ gradients in isolated mitochondria and intracellular Na+ levels
Range Responds to a range of intracellular Na+ around 10 mM Responds to Na+ in physiological range
Fluorophore CoroNa Green SBFI
Standard filter set FITC Requires excitation ratio to quantify Na+ levels
Ex/Em (nm) ~492/516 ~340 and 380/500
Bibliography Citations Citations
Cell permeant or impermeant? Impermeant Cell permeant Impermeant Cell permeant
Platforms Imaging Imaging Imaging Imaging
Usage notes Load by microinjection, patch pipette, or pinocytic loading agent Load in cell media Load by microinjection, patch pipette, or pinocytic loading agent Load in cell media
Format 1 mg 20 x 50 µg 1 mg 1 mg 20 x 50 µg
Cat. No. C36675 C36676 S1262 S1263 S1264