Skip to main content
NCBI home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1982;324:319–345. doi: 10.1113/jphysiol.1982.sp014115

Fast charge movements in skeletal muscle fibres from Rana temporaria

Carol A Collins 1,*, E Rojas 1, B A Suarez-Isla 1,†
PMCID: PMC1250708  PMID: 6980274

Abstract

1. Fast charge movements were measured in cut skeletal muscle fibres from Rana temporaria.

2. The initial time course of the current in response to a sudden displacement of the membrane potential from -110 to -60 mV was analysed in terms of an electrical equivalent circuit modified from Falk & Fatt (1964).

3. The specific resistance in series with the sarcolemma was estimated as 7·4 Ω cm2. The total capacity (surface sarcolemma plus tubular membrane) was estimated as 3·43 μF/cm2.

4. The asymmetry currents settling within 1 ms during depolarizing pulses of increasing size (on-response), from a holding potential around -120 mV, could be described in terms of a single exponential. The asymmetry currents after the pulses (off-response) exhibited at least two components.

5. The integral of the on-response, Qon, as a function of Vp, could be fitted using a function of the Boltzmann type. At the mid-point of the distribution curve, equal to -38 mV, the slope was 0·012 mV-1. A saturating value of 28 pC was reached at 40 mV.

6. The off-response to pulses not exceeding 3 ms exhibited two components. The first one had an exponential time course. The charge Qoff associated with this fast component was always equal to Qon.

7. τon (the relaxation time constant), as a function of membrane potential was asymmetrical, exhibiting a maximum value of 233 μs at about -38 mV.

8. For Vp values smaller than -20 mV the Qon—Vp and τon—Vp curves could be analysed using the two-state transition model. From this analysis the average transition potential V′ was estimated as -38 mV and the effective valence of the mobile charges as 1·36.

9. Double-pulse protocols (duration of pre-pulses referred to as T in the range 0-3 s) showed that Qon and τon decreased as T increased. Single transient analysis shows that the changes are confined to the transient for depolarizing pulses.

10. This immobilization of the charges is reversible and follows a similar time course to the slow inactivation of the Na+ conductance described in the preceding paper.

11. A differential effect of the depolarizing pre-pulse on the ionic and asymmetry currents is seen in the decrease of τon with increasing T while τm remains constant.

Full text

PDF
319

Selected References

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

  1. Adrian R. H., Chandler W. K., Hodgkin A. L. Voltage clamp experiments in striated muscle fibres. J Physiol. 1970 Jul;208(3):607–644. doi: 10.1113/jphysiol.1970.sp009139. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Adrian R. H. Charge movement in the membrane of striated muscle. Annu Rev Biophys Bioeng. 1978;7:85–112. doi: 10.1146/annurev.bb.07.060178.000505. [DOI] [PubMed] [Google Scholar]
  3. Armstrong C. M., Bezanilla F. Charge movement associated with the opening and closing of the activation gates of the Na channels. J Gen Physiol. 1974 May;63(5):533–552. doi: 10.1085/jgp.63.5.533. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Collins C. A., Rojas E., Suarez-Isla B. A. Activation and inactivation characteristics of the sodium permeability in muscle fibres from Rana temporaria. J Physiol. 1982 Mar;324:297–318. doi: 10.1113/jphysiol.1982.sp014114. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Eisenberg R. S., Gage P. W. Ionic conductances of the surface and transverse tubular membranes of frog sartorius fibers. J Gen Physiol. 1969 Mar;53(3):279–297. doi: 10.1085/jgp.53.3.279. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. FALK G., FATT P. LINEAR ELECTRICAL PROPERTIES OF STRIATED MUSCLE FIBRES OBSERVED WITH INTRACELLULAR ELECTRODES. Proc R Soc Lond B Biol Sci. 1964 Apr 14;160:69–123. doi: 10.1098/rspb.1964.0030. [DOI] [PubMed] [Google Scholar]
  7. 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]
  8. Hille B., Campbell D. T. An improved vaseline gap voltage clamp for skeletal muscle fibers. J Gen Physiol. 1976 Mar;67(3):265–293. doi: 10.1085/jgp.67.3.265. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Ildefonse M., Rougier O. Voltage-clamp analysis of the early current in frog skeletal muscle fibre using the double sucrose-gap method. J Physiol. 1972 Apr;222(2):373–395. doi: 10.1113/jphysiol.1972.sp009803. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Keynes R. D., Rojas E. Kinetics and steady-state properties of the charged system controlling sodium conductance in the squid giant axon. J Physiol. 1974 Jun;239(2):393–434. doi: 10.1113/jphysiol.1974.sp010575. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Keynes R. D., Rojas E. The temporal and steady-state relationships between activation of the sodium conductance and movement of the gating particles in the squid giant axon. J Physiol. 1976 Feb;255(1):157–189. doi: 10.1113/jphysiol.1976.sp011274. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Nakajima S., Hodgkin A. L. Effect of diameter on the electrical constants of frog skeletal muscle fibres. Nature. 1970 Sep 5;227(5262):1053–1055. doi: 10.1038/2271053a0. [DOI] [PubMed] [Google Scholar]
  13. Neumcke B., Nonner W., Stämpfli R. Asymmetrical displacement current and its relation with the activation of sodium current in the membrane of frog myelinated nerve. Pflugers Arch. 1976 Jun 22;363(3):193–203. doi: 10.1007/BF00594601. [DOI] [PubMed] [Google Scholar]
  14. Nonner W. A new voltage clamp method for Ranvier nodes. Pflugers Arch. 1969;309(2):176–192. doi: 10.1007/BF00586967. [DOI] [PubMed] [Google Scholar]
  15. Nonner W., Rojas E., Stämpfli R. Gating currents in the node of Ranvier: voltage and time dependence. Philos Trans R Soc Lond B Biol Sci. 1975 Jun 10;270(908):483–492. doi: 10.1098/rstb.1975.0024. [DOI] [PubMed] [Google Scholar]
  16. Pynsent P. B., Rojas E. Voltage clamp and data acquisition method for single myelinated nerve fibre work [proceedings]. J Physiol. 1979 Jun;291:14P–15P. [PubMed] [Google Scholar]
  17. Rojas E. Gating mechanism for the activation of the sodium conductance in nerve membranes. Cold Spring Harb Symp Quant Biol. 1976;40:305–320. doi: 10.1101/sqb.1976.040.01.031. [DOI] [PubMed] [Google Scholar]
  18. Rojas E., Keynes R. D. On the relation between displacement currents and activation of the sodium conductance in the squid giant axon. Philos Trans R Soc Lond B Biol Sci. 1975 Jun 10;270(908):459–482. doi: 10.1098/rstb.1975.0023. [DOI] [PubMed] [Google Scholar]
  19. 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]

Articles from The Journal of Physiology are provided here courtesy of The Physiological Society

RESOURCES