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Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1981 Feb;78(2):1274–1277. doi: 10.1073/pnas.78.2.1274

Identification and kinetic properties of the current through a single Na+ channel.

Y Fukushima
PMCID: PMC319991  PMID: 6262761

Abstract

The kinetic properties of a single Na+ channel in the tunicate egg cell membrane were studied by the patch-recording technique. A conventional micropipette filled with a solution of 600 mM NaCl and 1.5 mM MnCl2 was used as the patch electrode. The seal resistance between patch electrode and egg surface was more than 1000 M omega. In the patch recording, the current fluctuations at a given membrane potential consisted of pulse-like events of a uniform amplitude. The amplitude was 1 pA at -56 mV and decreased as the membrane potential was made more positive. It is suggested that the fluctuation in the patch current is the current through a single Na+ channel for the following reasons. First, the reversal potential of the pulse-like fluctuation in the patch current was approximately equal to that of the total membrane Na+ current in a solution equivalent to that in the patch electrode. Second, the charges transferred by the patch current and by the total membrane Na+ current during a 170-msec command pulse showed parallel dependence on membrane potential. Third, the kinetic properties of the pulse-like fluctuations in the patch current were analyzed according to the Hodgkin-Huxley model, and it was shown that the time sequences of the pulse-like events were compatible with those for a single Na+ channel.

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Selected References

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

  1. Conti F., Hille B., Neumcke B., Nonner W., Stämpfli R. Measurement of the conductance of the sodium channel from current fluctuations at the node of Ranvier. J Physiol. 1976 Nov;262(3):699–727. doi: 10.1113/jphysiol.1976.sp011616. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Conti F., Neher E. Single channel recordings of K+ currents in squid axons. Nature. 1980 May 15;285(5761):140–143. doi: 10.1038/285140a0. [DOI] [PubMed] [Google Scholar]
  3. 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]
  4. Neher E., Sakmann B., Steinbach J. H. The extracellular patch clamp: a method for resolving currents through individual open channels in biological membranes. Pflugers Arch. 1978 Jul 18;375(2):219–228. doi: 10.1007/BF00584247. [DOI] [PubMed] [Google Scholar]
  5. Ohmori H., Yoshii M. Surface potential reflected in both gating and permeation mechanisms of sodium and calcium channels of the tunicate egg cell membrane. J Physiol. 1977 May;267(2):429–463. doi: 10.1113/jphysiol.1977.sp011821. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Okamoto H., Takahashi K., Yoshii M. Membrane currents of the tunicate egg under the voltage-clamp condition. J Physiol. 1976 Jan;254(3):607–638. doi: 10.1113/jphysiol.1976.sp011249. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Ritchie J. M., Rogart R. B. The binding of saxitoxin and tetrodotoxin to excitable tissue. Rev Physiol Biochem Pharmacol. 1977;79:1–50. doi: 10.1007/BFb0037088. [DOI] [PubMed] [Google Scholar]
  8. Sigworth F. J. Sodium channels in nerve apparently have two conductance states. Nature. 1977 Nov 17;270(5634):265–267. doi: 10.1038/270265a0. [DOI] [PubMed] [Google Scholar]

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