Skip to main content
NCBI home page
The Journal of General Physiology logoLink to The Journal of General Physiology
. 1974 May 1;63(5):533–552. doi: 10.1085/jgp.63.5.533

Charge Movement Associated with the Opening and Closing of the Activation Gates of the Na Channels

Clay M Armstrong 1, Francisco Bezanilla 1
PMCID: PMC2203568  PMID: 4824995

Abstract

The sodium current (I Na) that develops after step depolarization of a voltage clamped squid axon is preceded by a transient outward current that is closely associated with the opening of the activation gates of the Na pores. This "gating current" is best seen when permeant ions (Na and K) are replaced by relatively impermeant ones, and when the linear portion of capacitative current is eliminated by adding current from positive steps to that from exactly equal negative ones. During opening of the Na pores gating current is outward, and as the pores close there is an inward tail of current that decays with approximately the same time-course as I Na recorded in Na-containing medium. Both outward and inward gating current are unaffected by tetrodotoxin (TTX). Gating current is capacitative in origin, the result of relatively slow reorientation of charged or dipolar molecules in a suddenly altered membrane field. Close association with the Na activation process is clear from the time-course of gating current, and from the fact that three procedures that reversibly block I Na also block gating current: internal perfusion with Zn2+, prolonged depolarization of the membrane, and inactivation of I Na with a short positive prepulse.

Full Text

The Full Text of this article is available as a PDF (1.1 MB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Armstrong C. M., Bezanilla F. M., Horowicz P. Twitches in the presence of ethylene glycol bis( -aminoethyl ether)-N,N'-tetracetic acid. Biochim Biophys Acta. 1972 Jun 23;267(3):605–608. doi: 10.1016/0005-2728(72)90194-6. [DOI] [PubMed] [Google Scholar]
  2. Armstrong C. M., Bezanilla F. Currents related to movement of the gating particles of the sodium channels. Nature. 1973 Apr 13;242(5398):459–461. doi: 10.1038/242459a0. [DOI] [PubMed] [Google Scholar]
  3. Armstrong C. M., Bezanilla F., Rojas E. Destruction of sodium conductance inactivation in squid axons perfused with pronase. J Gen Physiol. 1973 Oct;62(4):375–391. doi: 10.1085/jgp.62.4.375. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Armstrong C. M., Hille B. The inner quaternary ammonium ion receptor in potassium channels of the node of Ranvier. J Gen Physiol. 1972 Apr;59(4):388–400. doi: 10.1085/jgp.59.4.388. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Baker P. F., Hodgkin A. L., Ridgway E. B. Depolarization and calcium entry in squid giant axons. J Physiol. 1971 Nov;218(3):709–755. doi: 10.1113/jphysiol.1971.sp009641. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Bezanilla F., Armstrong C. M. Gating currents of the sodium channels: three ways to block them. Science. 1974 Feb 22;183(4126):753–754. doi: 10.1126/science.183.4126.753. [DOI] [PubMed] [Google Scholar]
  7. Bezanilla F., Armstrong C. M. Negative conductance caused by entry of sodium and cesium ions into the potassium channels of squid axons. J Gen Physiol. 1972 Nov;60(5):588–608. doi: 10.1085/jgp.60.5.588. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. COLE K. S., MOORE J. W. Potassium ion current in the squid giant axon: dynamic characteristic. Biophys J. 1960 Sep;1:1–14. doi: 10.1016/s0006-3495(60)86871-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Chandler W. K., Meves H. Voltage clamp experiments on internally perfused giant axons. J Physiol. 1965 Oct;180(4):788–820. doi: 10.1113/jphysiol.1965.sp007732. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Cohen L. B., Hille B., Keynes R. D., Landowne D., Rojas E. Analysis of the potential-dependent changes in optical retardation in the squid giant axon. J Physiol. 1971 Oct;218(1):205–237. doi: 10.1113/jphysiol.1971.sp009611. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. HODGKIN A. L., HUXLEY A. F. A quantitative description of membrane current and its application to conduction and excitation in nerve. J Physiol. 1952 Aug;117(4):500–544. doi: 10.1113/jphysiol.1952.sp004764. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Hille B. Common mode of action of three agents that decrease the transient change in sodium permeability in nerves. Nature. 1966 Jun 18;210(5042):1220–1222. doi: 10.1038/2101220a0. [DOI] [PubMed] [Google Scholar]
  13. MULLINS L. J. An analysis of conductance changes in squid axon. J Gen Physiol. 1959 May 20;42(5):1013–1035. doi: 10.1085/jgp.42.5.1013. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Meves H., Vogel W. Calcium inward currents in internally perfused giant axons. J Physiol. 1973 Nov;235(1):225–265. doi: 10.1113/jphysiol.1973.sp010386. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Narahashi T., Anderson N. C., Moore J. W. Comparison of tetrodotoxin and procaine in internally perfused squid giant axons. J Gen Physiol. 1967 May;50(5):1413–1428. doi: 10.1085/jgp.50.5.1413. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Schneider M. F., Chandler W. K. Voltage dependent charge movement of skeletal muscle: a possible step in excitation-contraction coupling. Nature. 1973 Mar 23;242(5395):244–246. doi: 10.1038/242244a0. [DOI] [PubMed] [Google Scholar]
  17. Takata M., Moore J. W., Kao C. Y., Fuhrman F. A. Blockage of sodium conductance increase in lobster giant axon by tarichatoxin (tetrodotoxin). J Gen Physiol. 1966 May;49(5):977–988. doi: 10.1085/jgp.49.5.977. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from The Journal of General Physiology are provided here courtesy of The Rockefeller University Press

RESOURCES