A change in the membrane potential in nerve cells is thought to be generated and propagated mainly by a function of K+ and Na+ channels. The concurrent monitoring of multipoints on the axon has been generally conducted on the basis of the voltage-clamp or current-clamp method. Given that the respective membrane potentials have been evaluated by considering the applied potential, local current, and conductance, the propagation of the change in the membrane potential was measured. By using a nerve model system composed of some liquid membrane cells, we directly measured the actual membrane potentials and the local currents of the respective cells. We demonstrated that the local membrane current caused by an external voltage induced a change in the membrane potential and that the change was propagated by connecting the liquid membrane cells and mimicking voltage-gated Na+ channels. It has been proved that hyperpolarization hardly occurs on the occasion of existence of the flux of K thorn and Na+ only in the present model system and that the change in the membrane potential corresponding to the action potential is directionally propagated. (C) 2018 Elsevier Ltd. All rights reserved.