Low permeabilities of MDCK cell monolayers: a model barrier epithelium

Researchers have measured the transepithelial electrical resistance and isotopic water and urea fluxes for Madin-Darby canine kidney (MDCK) type I and II cells. Attention was also given to type I cells expressing MUC1, the mucin protein, in their apical membranes. It was found that the apical membrane permeability of type I cells resembles that of other barrier epithelia. Abrupt introduction of water-permeable pores with nystatin into the apical membranes of barrier epithelia gives rise to prompt increases in water permeability.