Skip to main content
PMC home page
Biophysical Journal logoLink to Biophysical Journal
. 1991 Jun;59(6):1164–1170. doi: 10.1016/S0006-3495(91)82332-3

Open channel block by gadolinium ion of the stretch-inactivated ion channel in mdx myotubes.

A Franco Jr 1, B D Winegar 1, J B Lansman 1
PMCID: PMC1281197  PMID: 1714778

Abstract

Currents flowing through single stretch-inactivated ion channels were recorded from cell-attached patches on myotubes from mdx mice. Adding micromolar concentrations of gadolinium to patch electrodes containing normal saline produced rapid transitions in the single-channel current between the fully open and closed states. The kinetics of the current fluctuations followed the predictions of a simple model of open channel block in which the transitions in the current arise from the entry and exit of Gd from the channel pore: histograms of the open and closed times were well fit with single exponentials, the blocking rate depended linearly on the concentration of gadolinium in the patch electrode, and the unblocking rate was independent of the concentration of gadolinium. Hyperpolarizing the patch increased the rate of unblocking (approximately e-fold per 85 mV), suggesting the charged blocking particle can exit the channel into the cell under the influence of the applied membrane field. The rate of blocking was rapid and was independent of the patch potential, consistent with the rate of ion entry into the pore being determined by its rate of diffusion in solution. When channel open probability was reduced by applying suction to the electrode, the blocking kinetics were independent of the extent of inactivation, suggesting that mechanosensitive gating does not modify the structure of the channel pore.

Full text

PDF
1164

Selected References

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

  1. Blatz A. L., Magleby K. L. Correcting single channel data for missed events. Biophys J. 1986 May;49(5):967–980. doi: 10.1016/S0006-3495(86)83725-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Bulfield G., Siller W. G., Wight P. A., Moore K. J. X chromosome-linked muscular dystrophy (mdx) in the mouse. Proc Natl Acad Sci U S A. 1984 Feb;81(4):1189–1192. doi: 10.1073/pnas.81.4.1189. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Franco A., Jr, Lansman J. B. Calcium entry through stretch-inactivated ion channels in mdx myotubes. Nature. 1990 Apr 12;344(6267):670–673. doi: 10.1038/344670a0. [DOI] [PubMed] [Google Scholar]
  4. Franco A., Jr, Lansman J. B. Stretch-sensitive channels in developing muscle cells from a mouse cell line. J Physiol. 1990 Aug;427:361–380. doi: 10.1113/jphysiol.1990.sp018176. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Guharay F., Sachs F. Stretch-activated single ion channel currents in tissue-cultured embryonic chick skeletal muscle. J Physiol. 1984 Jul;352:685–701. doi: 10.1113/jphysiol.1984.sp015317. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Hamill O. P., Marty A., Neher E., Sakmann B., Sigworth F. J. Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers Arch. 1981 Aug;391(2):85–100. doi: 10.1007/BF00656997. [DOI] [PubMed] [Google Scholar]
  7. Lansman J. B. Blockade of current through single calcium channels by trivalent lanthanide cations. Effect of ionic radius on the rates of ion entry and exit. J Gen Physiol. 1990 Apr;95(4):679–696. doi: 10.1085/jgp.95.4.679. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Lansman J. B., Hess P., Tsien R. W. Blockade of current through single calcium channels by Cd2+, Mg2+, and Ca2+. Voltage and concentration dependence of calcium entry into the pore. J Gen Physiol. 1986 Sep;88(3):321–347. doi: 10.1085/jgp.88.3.321. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Neher E., Steinbach J. H. Local anaesthetics transiently block currents through single acetylcholine-receptor channels. J Physiol. 1978 Apr;277:153–176. doi: 10.1113/jphysiol.1978.sp012267. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Ogden D. C., Colquhoun D. Ion channel block by acetylcholine, carbachol and suberyldicholine at the frog neuromuscular junction. Proc R Soc Lond B Biol Sci. 1985 Sep 23;225(1240):329–355. doi: 10.1098/rspb.1985.0065. [DOI] [PubMed] [Google Scholar]
  11. Winegar B. D., Lansman J. B. Voltage-dependent block by zinc of single calcium channels in mouse myotubes. J Physiol. 1990 Jun;425:563–578. doi: 10.1113/jphysiol.1990.sp018118. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Woodhull A. M. Ionic blockage of sodium channels in nerve. J Gen Physiol. 1973 Jun;61(6):687–708. doi: 10.1085/jgp.61.6.687. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Yang X. C., Sachs F. Block of stretch-activated ion channels in Xenopus oocytes by gadolinium and calcium ions. Science. 1989 Feb 24;243(4894 Pt 1):1068–1071. doi: 10.1126/science.2466333. [DOI] [PubMed] [Google Scholar]
  14. Yellen G. Ionic permeation and blockade in Ca2+-activated K+ channels of bovine chromaffin cells. J Gen Physiol. 1984 Aug;84(2):157–186. doi: 10.1085/jgp.84.2.157. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Biophysical Journal are provided here courtesy of The Biophysical Society

RESOURCES