Assays to Measure Purinoceptor Pore Dilation.

The P2X7 receptor is a classic purinoceptor/ion channel. After activated by ATP, it opens a cation selective channel, which dilates to a large pore over tens of seconds, allowing the entry of big molecules. This unique feature is often used to evaluate this receptor's function with DNA-binding dyes (MW 300-400 Da), such as ethidium bromide and Yo-Pro-1. Here we describe two-color flow cytometry based protocols for measuring P2X7 pore dilation. One is ATP-induced ethidium uptake by real-time multicolor flow cytometry for standardized and accurate quantitation, and the other is a quick whole blood assay which is particularly useful for ex vivo study.