SBFI is a sodium-sensitive molecule used 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 used to correlate changes in intracellular Na+ with Ca2+ and Mg2+ concentrations, intracellular pH, and membrane potential. Although the selectivity of SBFI for Na+ is less than that of calcium indicators such as fura-2, it is sufficient for the detection of physiological concentrations of Na+ in the presence of other monovalent cations. The spectral response of SBFI upon ion binding permit excitation ratio measurements, and this indicator can be used with the same optical filters and equipment used for fura-2.
Fluorescent Ion Indicators Specifications: • Label (Ex/Em): SBFI (~340,380/500 nm) • Lyophilized product may be dissolved in DMSO for use • Product is typically loaded into cells by adding the dissolved indicator to medium containing cells
Selectivity Considerations and Cell Loading Strategies The dissociation constant (Kd) of SBFI for Na+ is 3.8 mM in the absence of K+, and 11.3 mM in solutions with a combined Na+ and K+ concentration of 135 mM (which approximates physiological ionic strength). SBFI is ~18-fold more selective for Na+ than for K+.
Find Fluorescent Indicators for Na+ and K+ We offer a number of fluorescent indicators for measuring Na+ and K+. Review Fluorescent Na+ and K+ Indicators—Section 21.1 in the Molecular Probes® Handbook for more information on these products.
For Research Use. Not for human or animal therapeutic or diagnostic use.
For Research Use Only. Not for use in diagnostic procedures.