ABSTRACT
The gap junction is a membrane complex which allows the interior of two adjacent cells to be linked via a hydrophilic channel. The role of gap junction channels in tissue and organ function has for a long time been recognized as one of allowing intercellular movement of cytoplasmic solutes and solvent, the only apparent restrictions being size and charge of solute. Before double whole-cell patch methods were used to study intercellular communication double-voltage-clamp and current-clamp methods were used to measure junctional membrane conductance and are still used to measure junctional membrane conductance accurately on a macroscopic scale. The double whole-cell patch can be used to study cell coupling where cell impedance is lower and the number of junctional channels is much greater. The double patch cannot resolve individual channels with such a high junctional conductance and its only advantage is that it involves using only one patch electrode per cell rather than two microelectrodes.
