Dual Patch Clamp

The main feature of gap junctions is the passage of ions and small molecules between adjacent cells. In the heart, for example, junctional currents between adjacent cells are elicited by the membrane potential difference when one of the cells generates an action potential, while the other cell is still at resting membrane potential, thereby allowing propagation of the action potential. Experimentally, such gap junctional currents can be directly evoked and measured by independently controlling the membrane voltage of both cells of a cell pair. This is accomplished by “dual voltage clamping” a cell-pair, a method introduced by Spray et al. (1). Using separate electrodes for voltage control and current injection, this technique allowed accurate determination of kinetics and conductance of gap junctions (1–3). At present, the dual voltage-clamp technique is usually performed with two patch pipets (4), each on one cell of a cell pair, which control voltage and measure current simultaneously (5–8).