Patent ID: 7371534

Claim:
A method for determining intracellular calcium comprising: adding to cells a dye precursor capable of entering the cells and being hydrolyzed to a dye, whereby the dye complexes with calcium in said cells and provides a luminescent signal, an antibody specific for the dye and not the dye precursor, said antibody conjugated with a quencher for quenching extracellular hydrolyzed dye precursor, said quencher being a p-aminophenylazo compound or a 4,5-dimethoxyfluorescein, and a cellular anion exchange enzyme inhibitor for inhibiting cell entry of extracellular calcium; incubating for sufficient time for said dye precursor to enter said cells; and determining in the presence of said dye precursor over a time span the change in the luminescent signal from said dye with decreased extracellular dye signal as a measure of intracellular calcium.