Fura-2 QBT Ratiometric Calcium Kit, a Novel Homogeneous Assay for Measuring Calcium Flux Assays on the FLIPR Tetra System and the FlexStation 3 Microplate Reader

Receptor-ligand mediated change in the concentration of intracellular calcium is one of the most common signal transduction events measured in cell-based assays. Calcium mobilization assays monitoring Gq-coupled GPCR activity using single wavelength dyes such as Fluo-4, can on occasion miss responses due to interference from a number of factors. Fura-2, being a dual wavelength calcium indicator, undergoes a spectral shift proportional to intracellular calcium concentration. As a result of the dual excitation, Fura-2 is typically not sensitive to the issues seen with most single wavelength dyes. One of the main drawbacks of using Fura-2 dye in the traditional method is the required wash step prior to running the assay. Washing cell plates can cause well to well variability, requires a large volume of buffer, and lowers throughput. This application note compares calcium flux responses from an alternative to the traditional Fura-2 wash assay and a competitor kit.