Electrophysiological Activities of Nerve Fiber and Chemical Properties of its Membrane

　When the voltage clamp technique was applied to a single Ranvier node of a toad，the so-called Na-current is obtained due to the excitation of the membrane．The Na-current has been explained by the Na-theory as an increase in Na-permeability of the nodal membrane during activity．

　Experimental setups for recording the action potential and the action current, and for the voltage clamp experiment of a singleRanvier node of a toad are shown in Fig. 1．