A new voltage clamp method for Ranvier nodes

Wolfgang Nonner

Research output: Contribution to journalArticle

174 Scopus citations

Abstract

A voltage clamp method for the membrane of Ranvier nodes is described and its error possibilities are discussed. The following principle is used: the potential in the axoplasm of the node is kept constant by negative feedback whereas the potential of the external fluid is adjusted to give the desired membrane potential. Potential changes in the nodal axoplasm are detected across one of the neighbouring internodes by the feedback amplifier input and are counteracted from its output across the other internode. A grounded guard electrode prevents couplings across the external solution between the potential applying electrode at the node and the amplifier input electrode and permits to record the full size of the membrane potential. A small air gap separates the guard and input electrode compartments; the other electrode compartments are isolated by vaseline seals. This method represents a further development of a method of Dodge and Frankenhaeuser (1958), which yields the following improvements: 1. Giving a transient response of 0.01-0.02 msec in myelinated nerve fibres of 12-15 μm diameter (Rana esculenta) it allows clamping at about 5 times larger rate. 2. No attenuation artifact is observed. 3. Drift of membrane potential is reduced. These improvements are due to a) using a feedback circuit containing one single feedback amplifier with exactly adapted frequency response b) using an air gap between the guard and the input electrode of the amplifier.

Original languageEnglish (US)
Pages (from-to)176-192
Number of pages17
JournalPflügers Archiv European Journal of Physiology
Volume309
Issue number2
DOIs
StatePublished - Jun 1 1969

Keywords

  • Air Gap
  • Myelinated Nerve Fibre
  • Ranvier Node
  • Voltage Clamp

ASJC Scopus subject areas

  • Physiology

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