Measurement of Intracellular Calcium Concentration Using Confocal Microscopy

Many cellular functions are tightly regulated by intracellular calcium concentrations ([Ca²⁺ ]_i ), and, therefore, the measurement of [Ca²⁺ ]_i is of critical importance. To determine Ca²⁺ -related cellular dynamics accurately, it is necessary to measure three-dimensionally resolved [Ca²⁺ ]_i with sufficient temporal resolution to follow fast cellular responses that generate signal pulses and wave propagation. Several techniques have been developed to assay [Ca²⁺ ]_i , but a revolution in the study of intracellular [Ca²⁺ ]_i occurred when fluorescent dyes for Ca²⁺ were developed (1 ). Since then, fluorescent dyes and fluorescent microscopy have been used to observe resting and nonresting [Ca²⁺ ] in intact cells as well as in subcellular fractions.