Cell Meter? Flow Cytometric Calcium Assay Kit. Cell Meter? Flow Cytometric Calcium Assay Kit provides fluorescence-based assays for detecting intracellular calcium mobilization using a flow cytometer. It can be used for kinetic reading or for endpoint reading. After loading the Calbryte? 520 AM dye into cells of interest, simply wash the cells and add the calcium flux agonist, one can then read the sample via a flow cytometer using kinetic reading mode or endpoint reading mode at Ex/Em = 490/525 nm. Calbryte? 520 AM can cross cell membrane passively by diffusion. Once inside the cells, the lipophilic blocking groups of Calbryte? 520 AM are cleaved by esterase, resulting in a negatively charged fluorescent dye that stays inside cells. Its fluorescence is greatly enhanced upon binding to calcium. When cells expressing GPCR of interest are stimulated with an agonist, the receptor signals the release of intracellular calcium, which significantly increases the fluorescence of Calbryte? 520. The Cell Meter? Flow Cytometric Calcium Assay Kit can be used for monitoring cellular calcium flux as well as cell sorting.