Invitrogen™ PBFI, Tetraammonium Salt, cell impermeant

• Although selectivity of PBFI for K⁺ is less than that of calcium indicators such as fura-2, it is sufficient for detection of physiological concentrations of K⁺ in presence of other monovalent cations
• Spectral response of PBFI upon ion binding permit excitation ratio measurements, and this indicator can be used with same optical filters and equipment used for fura-2
• Label (Ex/Em): PBFI (approximately 340,380/500nm)
• Lyophilized product may be dissolved in distilled water or aqueous buffer for use
• Product is typically loaded into cells by diffusion from patch pipet for correlated fluorescence imaging and electrophysiological recording
• K_d of PBFI for K⁺ is strongly dependent on whether Na⁺ is present, with value of 5.1mm in absence of Na⁺ and 44mm in solutions with combined Na⁺ and K⁺ concentration of 135 mm (which approximates physiological ionic strength)
• Although PBFI is only 1.5-fold more selective for K⁺ than for Na⁺, this selectivity is often sufficient because intracellular K⁺ concentrations are normally about 10 times higher than Na⁺ concentrations

Cell Analysis, Cell Metabolism, Cell Viability, Proliferation and Function, Ionic Homeostasis and Signaling, Sodium and Potassium Detection