Introduction
Carboxy-DCFDA (5-(and-6)-Carboxy-2′,7′-Dichlorofluorescein Diacetate) is a reagent that passively diffuses into cells. It is colorless / nonfluorescdent and is cleaved by intracellular esterases to yield a fluoresecent fluirophore, 5-(and-6)-carboxy-2′,7′ –dichlorofluorescein (CDFDA). This reagent can be used to visualize the formation of bile canaliculi in polarized hepatocytes which is indicative of MRP-2 trasnporter activity. Carboxy-DCFDA is a substrate of multidrug resistance-associated protein 2 (MRP2), a hepatocyte efflux transporter, thus it can be used to visualize MRP2-mediated canalicular uptake and efflux, as well as to label the bile canaliculi structures.