The parallelism between the action potential, action current, and membrane resistance at a node of Ranvier.

1. Simultaneous measurements of action potential and resistance and of action current and impedance change have been made at a single node of Ranvier. 2. There is a parallelism between action potential, action current, and resistance change measured at a node of Ranvier. 3. Some implications of these results have been discussed in relation to the corresponding data obtained from the squid giant axon.