Localizing transepithelial conductive pathways using a vibrating voltage probe.

Abstract

A model simulation of the electrical field distribution for the voltage-activated C1- current across amphibian skin has been carried out for two potential pathways, i.e. transcellularly, through the mitochondria-rich cells (MRCs), or paracellularly, across the tight junctions (TJs) between the outermost living cell layer. The calculations are based on the mean density of MRCs and the typical dimensions of stratum granulosum cells of amphibian skin. It is demonstrated that current flow across MRCs would be detectable by scanning with the vibrating voltage probe in the extracellular space above the epithelium, whereas accurate representation of current flow through the TJs cannot be obtained using a probe of the present design. The experimental data indicate that field patterns corresponding to an MRC origin for the C1- current are never observed. It is concluded that the voltage-activated C1- conductance is localized to ion-selective structures in the paracellular pathway which may be regulated by the TJs.