Pflügers Archiv

, Volume 366, Issue 2–3, pp 273–276 | Cite as

The theoretical small signal impedance of the frog node,Rana pipiens

  • David E. Clapham
  • Louis J. de Felice
Letters and Notes


The small signal impedance of the frog node is calculated for frequencies from 1 Hz to 10,000 Hz and transmembrane potentials from −80 mV to −30 mV by linearizing the voltage clamp equations of Dodge [7] and Hille [8]. The modulus of the impedance is presented for the total system, and separately for the potassium and sodium systems as a function of frequency and voltage. There is a broad resonance in the total impedance with a voltage-dependent peak frequency. At 22°C, in the range −75 mV to −45 mV, the peak frequencies occur between 50 and 500 Hz. Removing the potassium system leaves a relatively shapr resonance centered around 200 Hz at −45 mV.

Key Words

Frog node Small signal impedance Membrane noise 


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Copyright information

© Springer-Verlag 1976

Authors and Affiliations

  • David E. Clapham
    • 2
  • Louis J. de Felice
    • 1
  1. 1.Department of AnatomyEmory UniversityAtlantaUSA
  2. 2.School of Electrical EngineeringGeorgia Institute of TechnologyAtlantaUSA

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