USSING CHAMBER FOR HIGH-FREQUENCY TRANSMURAL IMPEDANCE ANALYSIS OF EPITHELIAL TISSUES

An Ussing chamber was designed for impedance analysis of epithelial ti ssue and optimized for the use of high-frequency alternating current s timuli. Shielded voltage electrodes, located axially within the electr ic field of the Ussing chamber, minimized the reactive properties of t he set-up. By vectorial subtraction, the small reactive contribution o f the optimized Ussing chamber was completely compensated for. This me thod allowed for transmural impedance measurements in a frequency rang e of 1-65 kHz. For the first time, Nyquist plots of cultured intestina l cell monolayers (HT-29/B6) are presented. The epithelial monolayers in different stages of confluence showed the impedance locus as a semi circle, with the high frequency end close to the origin. These epithel ial monolayers could be modeled by a simple RC-parallel circuit withou t a series resistance. (C) 1997 Elsevier Science B.V.