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Fig. 1. Transepithelial impedance analysis. (A) Electrical equivalent circuit of
the epithelium. See Materials and Methods for explanation. (B) Typical
impedance data (open circles) of an C7-cld-2 monolayer (transfected with
claudin-2 cDNA) in regular Ringer's solution and in low Ca2+
Ringer's. The Nyquist plot shows the real and the imaginary parts of the
transepithelial impedance as a function of frequency. Dots on a solid line
depict the least-squares fit of the data to the electrical model.