Assay Kit Mechanism

The assay exploits the permeability of thallium (Tl+) for potassium (K+) channels. The cells are incubated with an AM ester form of a fluorescent thallium sensitive dye. Intracellular esterases cleave off the AM group trapping the dye within the cells. Cells are then stimulated with either a mixture of K+ and Tl+ or a ligand in the presence of Tl+. The increase in fluorescent signal represents the influx of Tl+ into the cell specifically through the potassium channel and becomes a measure of potassium channel functional activity. Background is reduced by the masking solution.