Ion Flux Assays
Rubidium 86Rb+ efflux assays measure potassium channel activity. In this assay, rubidium acts as a tracer for potassium movement across the cell membrane. Calcium-sensitive potassium channel are loaded with 86Rb+, washed, and then incubated under experimental conditions. The cell supernatant is removed, and the remaining cell monolayer lysed. These two samples contain 86Rb+ that has moved out of the cell and 86Rb+ that remains in the cell, respectively. Measurement of the 86Rb+ content of these samples by flame atomic absorption spectrometry allows calculation of the percentage 86Rb+ efflux and, depending on the experimental design, provides pharmacological data about the control and test compounds used.