Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Experiment Videos

On the persistent sodium current in squid giant axons.

John R Clay1

  • 1Ion Channel Biophysics Unit, Basic Neurosciences Program, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA. jrclay@ninds.nih.gov

Journal of Neurophysiology
|January 11, 2003
PubMed
Summary

A distinct ion channel mechanism likely underlies most of the persistent sodium ion current (I(NaP)) in squid giant axons, separate from the classical sodium current (I(Na)). This finding challenges previous attributions of I(NaP) to I(Na) at low membrane potentials.

Related Concept Videos

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Novel description of the large conductance Ca<sup>2+</sup>-modulated K<sup>+</sup> channel current, BK, during an action potential from suprachiasmatic nucleus neurons.

Physiological reports·2017
Same author

A Novel Method for the Description of Voltage-Gated Ionic Currents Based on Action Potential Clamp Results-Application to Hippocampal Mossy Fiber Boutons.

Frontiers in cellular neuroscience·2016
Same author

Novel description of ionic currents recorded with the action potential clamp technique: application to excitatory currents in suprachiasmatic nucleus neurons.

Journal of neurophysiology·2015
Same author

A novel analysis of excitatory currents during an action potential from suprachiasmatic nucleus neurons.

Journal of neurophysiology·2013
Same author

Ionic mechanism underlying optimal stimuli for neuronal excitation: role of Na+ channel inactivation.

PloS one·2012
Same author

A comparative analysis of models of Na+ channel gating for mammalian and invertebrate nonmyelinated axons: relationship to energy efficient action potentials.

Progress in biophysics and molecular biology·2012

Area of Science:

  • Neuroscience
  • Ion Channel Physiology
  • Biophysics

Background:

  • A persistent sodium ion current (I(NaP)) with a low threshold has been reported in squid giant axons.
  • The contribution of the classical sodium ion current (I(Na)) to I(NaP) is debated and depends on slow inactivation kinetics.

Purpose of the Study:

  • To differentiate the ion channel mechanisms responsible for the persistent sodium ion current (I(NaP)) from the classical sodium ion current (I(Na)) in squid giant axons.

Main Methods:

  • Analysis of the contribution of I(Na) to I(NaP), critically dependent on the slow inactivation of I(Na).
  • Utilized the Vandenberg and Bezanilla model of I(Na) gating in squid giant axons to predict I(Na) behavior.
  • Subtracted the predicted I(Na) contribution from measured I(NaP) to isolate distinct current components.

Related Experiment Videos

Main Results:

  • Steady-state inactivation of I(Na) is complete above -40 mV, making its contribution to I(NaP) unlikely in this range.
  • The Vandenberg and Bezanilla model predicts I(Na) has a threshold of -60 mV and a peak amplitude of -25 microA/cm(2) at -20 mV.
  • Modulation by slow inactivation predicts a finite persistent current from I(Na) in the -60 to -40 mV range, peaking at -1 microA/cm(-2) at -50 mV.

Conclusions:

  • Most of the observed I(NaP) in squid giant axons is likely attributable to an ion channel mechanism distinct from I(Na).
  • The low threshold and amplitude characteristics of I(NaP) are not fully explained by the classical I(Na) current, even with slow inactivation.