Measuring the change in calcium flux in cell-based assays is a very useful tool for monitoring the downstream effects of receptor activation or inhibition. For instance, activated Gαq coupled G-protein coupled receptors (GPCRs) such as the Serotonin 5-HT2, Histamine H1, or the Vasopressin 1 receptors, will subsequently activate the phosopholipase C (PLC) signaling cascade, which ultimately, amongst other things, results in an intracellular calcium flux.As a way to study the activation of such receptors connected to changes in calcium flux, several different luminescence and fluorescence assays have been developed that can work in a microplate-based environment. Calcium flux assays work the best on microplate readers that can measure and inject into a well at the same time. Since calcium flux assays occur extremely fast, instruments only have seconds to capture the necessary measurements. With simultaneous injection and measurement, every data point is captured before, during, and after injection.
Over the years, many different calcium signaling compounds have been created that can be used on microplate readers. Here is a brief and unfinished list of some of the more popular calcium flux assays on the market:
- Fura-2, Fluo-3 were first generation dyes
- Fluo-4 Direct™
- Aequorin Luminescence
- Clonetics™ luminescence primary sensor
- FLIPR® fluorescence calcium assay kit
- Oregon® Green
The following BMG LABTECH microplate readers can perform calcium flux assays, LUMIstar, FLUOstar and POLARstar OPTIMA; LUMIstar, FLUOstar and POLARstar Omega; PHERAstar FS; and the NOVOstar.