Transport of compound through MDCK cell monolayer is used for measuring rate of membrane transport, expressed as apparent (Papp) permeability. Resulting Papp values from both transport directions (apical to basolateral side, and basolateral to apical side) are used for calculation of efflux ratio, as well as of net flux ratio (if MDCK-MDR1 data are available).
MDCK cells (wild type) are Madin-Darby canine kidney epithelial cells. They endogenously express different transporters, such as canine P-glycoprotein (P-gp). Therefore, it is recommended to analyze a test compound on both MDCK and MDCK-MDR1 cell monolayer and determine the real role of human P-gp on transport of the test compound.