Impedanzmessungen an Ranvierschen Schn�rringen unter Einwirkung von Nickelchlorid

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1. Impedance changes accompanying the markedly prolonged action currents of single Ranvier nodes in cold Ringer's solution containing 10−4–10−3 M N1Cl2 have been measured by means of a Wheatstone bridge followed by a phase-sensitive rectifier. 2. Maximum impedance decrease coincides with the peak of the action current. Impedance increases continously during the plateau, but remains far below the resting impedance; it rises most rapidly at the end of the plateau. Complete recovery of the resting impedance is reached 7–43 msec after the end of the action current. 3. Similar results are obtained by recording the action potential of the node and measuring the potential changes produced by alternating currents of constant strength. 4. The impedance changes are referred to changes of the ionic slope conductances G Na and G K.