Figure 4.Equivalent electric circuit used to obtain estimates of the apical and basolateral membrane resistances (R) and capacitances (C) by impedance analysis. Two RC elements are shown connected in series and represent the apical and basolateral membranes, respectively. The RC elements are also connected in parallel with the paracellular pathway (PCP) shunt resistance (RP) and a series resistance (RS) for the solution resistance between the measuring electrodes and the cell monolayer.