Abstract
1. Asymmetrical displacement currents ('gating currents') and Na currents have been recorded in intracellularly perfused squid giant axons with the voltage-clamp method. Inactivation of the currents by a long-lasting depolarization to -30 mV and subsequent removal of inactivation have been studied at temperatures of 0-5-3 degrees and 8-9 degrees C. 2. The asymmetrical displacement current, recorded with the divided pulse procedure, was markedly reduced by a 1-5-800 msec depolarization to -30 mV; a 3 min depolarization led to almost complete blockage. 3. Recovery of the asymmetrical displacement current from a 3 min depolarization to -30 mV was slow (20-40% recovery after 50-800 msec at -70 mV and 8-9 degrees C); full recovery from a long-lasting depolarization took several minutes. 4. Recovery of the Na current followed a similar time course (20% recovery after 50-800 msec at -70 mV and 8-9 degrees C); the time constant of full recovery was 2-3-5 min. 5. Slow recovery was also demonstrated by recording the displacement currents associated with single depolarizing pulses. 6. The results are consistent with the idea that the asymmetrical displacement current is related to the function of the Na gates.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Adelman W. J., Jr, Palti Y. The effects of external potassium and long duration voltage conditioning on the amplitude of sodium currents in the giant axon of the squid, Loligo pealei. J Gen Physiol. 1969 Nov;54(5):589–606. doi: 10.1085/jgp.54.5.589. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Armstrong C. M. Currents associated with the ionic gating structures in nerve membrane. Ann N Y Acad Sci. 1975 Dec 30;264:265–277. doi: 10.1111/j.1749-6632.1975.tb31488.x. [DOI] [PubMed] [Google Scholar]
- 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]
- Chandler W. K., Hodgkin A. L., Meves H. The effect of changing the internal solution on sodium inactivation and related phenomena in giant axons. J Physiol. 1965 Oct;180(4):821–836. doi: 10.1113/jphysiol.1965.sp007733. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Chandler W. K., Meves H. Slow changes in membrane permeability and long-lasting action potentials in axons perfused with fluoride solutions. J Physiol. 1970 Dec;211(3):707–728. doi: 10.1113/jphysiol.1970.sp009300. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fox J. M. Ultra-slow inactivation of the ionic currents through the membrane of myelinated nerve. Biochim Biophys Acta. 1976 Mar 5;426(2):232–244. doi: 10.1016/0005-2736(76)90334-5. [DOI] [PubMed] [Google Scholar]
- Meves H. The effect of holding potential on the asymmetry currents in squid gaint axons. J Physiol. 1974 Dec;243(3):847–867. doi: 10.1113/jphysiol.1974.sp010780. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Meves H. The effect of zinc on the late displacement current in squid giant axons. J Physiol. 1976 Jan;254(3):787–801. doi: 10.1113/jphysiol.1976.sp011259. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Meves H., Vogel W. Inactivation of the asymmetrical displacement current in giant axons of Loligo forbesi. J Physiol. 1977 May;267(2):377–393. doi: 10.1113/jphysiol.1977.sp011818. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rudy B. Proceedings: Slow recovery of the inactivation of sodium conductance in Myxicola giant axons. J Physiol. 1975 Jul;249(1):22P–24P. [PubMed] [Google Scholar]
- Rudy B. Sodium gating currents in Myxicola giant axons. Proc R Soc Lond B Biol Sci. 1976 Jun 30;193(1113):469–475. doi: 10.1098/rspb.1976.0059. [DOI] [PubMed] [Google Scholar]
- Schauf C. L., Pencek T. L., Davis F. A. Slow sodium inactivation in Myxicola axons. Evidence for a second inactive state. Biophys J. 1976 Jul;16(7):771–778. doi: 10.1016/S0006-3495(76)85727-X. [DOI] [PMC free article] [PubMed] [Google Scholar]