Product 7641

Fura-4F, AM is a cell-permeant, fluorescent ion indicator for intracellular Ca²⁺ measurements. Live cells are passively loaded with Fura-4F, AM by incubation with the cell membrane-permeant AM esters. Once internalized, cytosolic esterases cleave the AM esters to liberate the active Fura-4F penta-carboxylate ion indicator. Fura-4F’s spectral response to Ca²⁺ ion-binding permits a ratiometric calculation of ion concentration that cancels artifacts of photobleaching, dye concentration gradients, cell thickness and dye leakage. The excitation wavelength of Fura-4F varies with Ca²⁺ concentration and shifts to shorter wavelengths with increasing Ca²⁺ concentration. The ratio of fluorescence intensity at 510 nm when excited at 340/380 nm is used for ratiometric calculation of Ca²⁺ ion concentration. Fura-4F is a lower affinity indicator for calcium and is useful for measurements of higher physiological concentrations of calcium ions where a higher affinity indicator would be fully saturated. .