The Journal of General Physiology
Axon Instruments microelectrode amplifiers
  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents
This Article
Right arrow Full Text (PDF, 816K)
Right arrow Alert me when this article is cited
Services
Right arrow Email this article
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new content in the JGP
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Fernandez, J. M.
Right arrow Articles by Bezanilla, F.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Fernandez, J. M.
Right arrow Articles by Bezanilla, F.
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati  
What's this?

The Journal of General Physiology, Vol 82, 331-346, Copyright © 1983 by The Rockefeller University Press

ARTICLES

Induced capacitance in the squid giant axon. Lipophilic ion displacement currents

JM Fernandez, RE Taylor and F Bezanilla

Voltage-clamped squid giant axons, perfused internally and externally with solutions containing 10(-5) M dipicrylamine (DpA-), show very large polarization currents (greater than or equal to 1 mA/cm2) in response to voltage steps. The induced polarization currents are shown in the frequency domain as a very large voltage-and frequency-dependent capacitance that can be fit by single Debye-type relaxations. In the time domain, the decay phase of the induced currents can be fit by single exponentials. The induced polarization currents can also be observed in the presence of large sodium and potassium currents. The presence of the DpA- molecules does not affect the resting potential of the axons, but the action potentials appear graded, with a much-reduced rate of rise. The data in the time domain as well as the frequency domain can be explained by a single-barrier model where the DpA- molecules translocate for an equivalent fraction of the electric field of 0.63, and the forward and backward rate constants are equal at -15 mV. When the induced polarization currents described here are added to the total ionic current expression given by Hodgkin and Huxley (1952), numerical solutions of the membrane action potential reproduce qualitatively our experimental data. Numerical solutions of the propagated action potential predict that large changes in the speed of conduction are possible when polarization currents are induced in the axonal membrane. We speculate that either naturally occurring substances or drugs could alter the cable properties of cells in a similar manner.
Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Reddit Reddit   Add to Technorati Technorati    What's this?


This article has been cited by other articles:


Home page
 Biophys. JHome page
S. Mennerick, M. Lamberta, H.-J. Shu, J. Hogins, C. Wang, D. F. Covey, L. N. Eisenman, and C. F. Zorumski
Effects on Membrane Capacitance of Steroids with Antagonist Properties at GABAA Receptors
Biophys. J., July 1, 2008; 95(1): 176 - 185.
[Abstract] [Full Text] [PDF]

Home page
 J. Neurosci.Home page
L. Sjulson and G. Miesenbock
Rational Optimization and Imaging In Vivo of a Genetically Encoded Optical Voltage Reporter
J. Neurosci., May 21, 2008; 28(21): 5582 - 5593.
[Abstract] [Full Text] [PDF]

Home page
 JGPHome page
M. DiFranco, J. Capote, M. Quinonez, and J. L. Vergara
Voltage-dependent Dynamic FRET Signals from the Transverse Tubules in Mammalian Skeletal Muscle Fibers
J. Gen. Physiol., November 26, 2007; 130(6): 581 - 600.
[Abstract] [Full Text] [PDF]


  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents