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. 1984 Apr;349:329–351. doi: 10.1113/jphysiol.1984.sp015159

Potassium current noise induced by barium ions in frog skeletal muscle.

T E DeCoursey, O F Hutter
PMCID: PMC1199340  PMID: 6330347

Abstract

Ba2+ was used to introduce K+ current fluctuations in addition to those arising from the intrinsic 'gating' mechanism studied in the preceding paper. In the presence of 0.5 to 2.0 mM-Ba2+, Lorentzian spectra were observed at potentials between -10 and -63 mV. The amplitude and corner frequency of these Lorentzian spectra varied with voltage in the general manner to be expected from the voltage- and time-dependent blocking action of Ba2+, but the microscopically determined time constant was consistently faster than that determined from the intensification of block upon hyperpolarization. The variance of the Ba2+-induced fluctuations could be used to calculate the limiting single-channel conductance, gamma, without the need to assume a specific model for inward rectification. The value of gamma obtained for preparations in symmetrical 120 mM-K+ was about 8 pS (20-24 degrees), in good agreement with that found in the preceding paper. Some fibres underwent a spontaneous, large increase in membrane conductance. This conductance showed inward rectification in the positive quadrant. At negative potentials this high conductance was blocked by 1 mM-Ba2+ in a voltage- and time-dependent manner. The block became faster and more complete at more negative potentials. Analysis of current noise in the high conductance state in the presence of Ba2+ gave Lorentzian spectra with corner frequencies in general agreement with the time constant of macroscopic current relaxations. The unitary conductance in that state was estimated to be at least 70 pS.

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Selected References

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

  1. Adrian R. H., Peachey L. D. Reconstruction of the action potential of frog sartorius muscle. J Physiol. 1973 Nov;235(1):103–131. doi: 10.1113/jphysiol.1973.sp010380. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. DeCoursey T. E., Dempster J., Hutter O. F. Inward rectifier current noise in frog skeletal muscle. J Physiol. 1984 Apr;349:299–327. doi: 10.1113/jphysiol.1984.sp015158. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Fink R., Hase S., Lüttgau H. C., Wettwer E. The effect of cellular energy reserves and internal calcium ions on the potassium conductance in skeletal muscle of the frog. J Physiol. 1983 Mar;336:211–228. doi: 10.1113/jphysiol.1983.sp014577. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Fink R., Lüttgau H. C. An evaluation of the membrane constants and the potassium conductance in metabolically exhausted muscle fibres. J Physiol. 1976 Dec;263(2):215–238. doi: 10.1113/jphysiol.1976.sp011629. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Fink R., Wettwer E. Modified K-channel gating by exhaustion and the block by internally applied TEA+ and 4-aminopyridine in muscle. Pflugers Arch. 1978 May 31;374(3):289–292. doi: 10.1007/BF00585607. [DOI] [PubMed] [Google Scholar]
  6. Fukushima Y. Blocking kinetics of the anomalous potassium rectifier of tunicate egg studied by single channel recording. J Physiol. 1982 Oct;331:311–331. doi: 10.1113/jphysiol.1982.sp014374. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Hagiwara S., Miyazaki S., Moody W., Patlak J. Blocking effects of barium and hydrogen ions on the potassium current during anomalous rectification in the starfish egg. J Physiol. 1978 Jun;279:167–185. doi: 10.1113/jphysiol.1978.sp012338. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Latorre R., Vergara C., Hidalgo C. Reconstitution in planar lipid bilayers of a Ca2+-dependent K+ channel from transverse tubule membranes isolated from rabbit skeletal muscle. Proc Natl Acad Sci U S A. 1982 Feb;79(3):805–809. doi: 10.1073/pnas.79.3.805. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Neumcke B. Fluctuation of Na and K currents in excitable membranes. Int Rev Neurobiol. 1982;23:35–67. doi: 10.1016/s0074-7742(08)60621-2. [DOI] [PubMed] [Google Scholar]
  10. Pallotta B. S., Magleby K. L., Barrett J. N. Single channel recordings of Ca2+-activated K+ currents in rat muscle cell culture. Nature. 1981 Oct 8;293(5832):471–474. doi: 10.1038/293471a0. [DOI] [PubMed] [Google Scholar]
  11. Schwarz W., Neumcke B., Palade P. T. K-current fluctuations in inward-rectifying channels of frog skeletal muscle. J Membr Biol. 1981;63(1-2):85–92. doi: 10.1007/BF01969449. [DOI] [PubMed] [Google Scholar]
  12. Standen N. B., Stanfield P. R. A potential- and time-dependent blockade of inward rectification in frog skeletal muscle fibres by barium and strontium ions. J Physiol. 1978 Jul;280:169–191. doi: 10.1113/jphysiol.1978.sp012379. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Standen N. B., Stanfield P. R. Rubidium block and rubidium permeability of the inward rectifier of frog skeletal muscle fibres. J Physiol. 1980 Jul;304:415–435. doi: 10.1113/jphysiol.1980.sp013333. [DOI] [PMC free article] [PubMed] [Google Scholar]

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