Transepithelial resistance and inulin permeability as endpoints in in vitro nephrotoxicity testing

Transepithelial electrical resistance (R-T) and the flux of fluorescein isothiocyanate (FITC) across Madin Darby canine kidney (MDCK) strain 1 cells and porcine epithelial kidney (LLC-PK1) monolayers were compared between three laboratories for a range of nephrotoxins. The precision of the REMS AutoSampler was similar to that of the Ussing chamber and the ENDOHM(R) technique, but superior to using chopstick electrodes, for measurements of resistance. The nephrotoxins used were selective for the proximal tubule, and in all cases, LLC-PK1 cells were more sensitive than MDCK cells. In most cases, change in R-T was a more sensitive indicator of damage than alterations in FITC flux. The REMS system provides high intra-plate precision for R-T measurements and is a higher throughput system, which is applicable to screening for nephrotoxicity in vitro.