Impedance analysis of epithelial and endothelial cell monolayers cultured on gold surfaces.

The present study describes a new method to determine transepithelial and transendothelial electrical resistances (TER) of cultured cell monolayers which is based on impedance analysis. To obtain impedance data of the epithelia or endothelia under investigation, we developed special measuring chambers that allow to culture the cells on gold surfaces that are used as measuring electrodes. Impedance analysis is carried out in the frequency range from 1 to 10(5) s-1 under normal culture conditions using a self-developed continuous wave impedance spectrometer. Evaluation of impedance data is achieved by fitting (NLSQ) the parameters of appropriate equivalent circuits to the experimental data. We investigated cell monolayers of primary cultured endothelial cells isolated from porcine brain microvessels, epithelial cells from porcine choroid plexus as well as those of the epithelial cell line MDCK. Transepithelial resistances were found to be in good agreement with published data. The main advantages of the new technique are the ability (i) to use multi-electrode arrays that allow to determine TERs at different locations of a given cell monolayer; (ii) to carry out impedance analysis under normal culture conditions; and (iii) to obtain TER values of cell monolayers grown on impermeable supports, which means that conditions cells are normally exposed to in ordinary culture dishes are maintained.