Mammalian purinoreceptors respond to extracellular nucleotides and their metabolites, for example, following the release of ATP or NAD+ from cells and their hydrolysis by ectonucleotidases. Membrane purinoreceptors are expressed as ionotropic ligand-gated ion channels designated P2X receptors, or as metabotropic G-protein coupled receptors designated P1 or P2Y receptors, on the cell surface of different cell types. In this chapter, we provide protocols to monitor the expression and activity of purinoreceptors on the cell membrane of living cells by flow cytometry.
