Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Conductances of single ion channels opened by nicotinic agonists are indistinguishable


Hypotheses concerning the mechanism by which acetylcholine-like agonists cause ion channels to open often suppose that the receptor–ionophore complex can exist in either of two discrete conformations, open and shut1–3. On the basis of noise analysis it has been reported that certain agonists open ion channels of lower conductance than usual4–8, though many potent agonists give similar conductances9–13, and hence that differences in the conductance of ion channels opened by different agonists may contribute to differences in efficacy14. Here we have reinvestigated this question by recording single ion channel currents15 evoked by acetylcholine-like agonists on embryonic rat muscle in tissue culture and on adult frog muscle endplate. Ten different agonists (Fig. 1) were tested, including several that noise analysis has suggested have a low conductance4,5. The single-channel conductance was found to be the same, within a few per cent, for all 10 agonists. It seems that noise analysis has given erroneously low conductances in some cases. Therefore efficacy differences do not depend on differences in single-channel conductances evoked by various agonists but presumably on the position of the open–shut equilibrium of the agonist–channel complexes16.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Get just this article for as long as you need it


Prices may be subject to local taxes which are calculated during checkout


  1. Katz, B. & Miledi, R. J. Physiol., Lond. 224, 665–669 (1972).

    Article  CAS  Google Scholar 

  2. Anderson, C. R. & Stevens, C. F. J. Physiol., Lond. 235, 655–691 (1973).

    Article  CAS  Google Scholar 

  3. Changeux, J. P. Harvey Lect. 75, 85–254 (1980).

    CAS  Google Scholar 

  4. Colquhoun, D., Dionne, V. E., Steinbach, J. H. & Stevens, C. F. Nature 253, 204–206 (1975).

    Article  ADS  CAS  Google Scholar 

  5. Dreyer, F., Walther, C. & Peper, K. Pflügers Arch. ges. Physiol. 366, 1–9 (1976).

    Article  CAS  Google Scholar 

  6. Spivak, C. E., Waters, J., Witkop, B. & Albuquerque, E. X. Molec. Pharmac. 23, 337–343 (1983).

    CAS  Google Scholar 

  7. Auerbach, A., del Castillo, J., Specht, P. C. & Titmus, M. J. Physiol., Lond. 343, 551–568 (1983).

    Article  CAS  Google Scholar 

  8. Stettmeier, H. & Finger, W. Pflügers Arch. ges. Physiol. 397, 237–242 (1983).

    Article  CAS  Google Scholar 

  9. Gray, P. T. A. & Rang, H. P. Br. J. Pharmac. 80, 235–240 (1983).

    Article  CAS  Google Scholar 

  10. Jackson, M. B., Lecar, H., Askanas, V. & Engel, W. K. J. Neurosci. 2, 1465–1473 (1982).

    Article  CAS  Google Scholar 

  11. Peper, K., Bradley, J. & Dreyer, F. Physiol. Rev 62, 1279–1340 (1982).

    Article  Google Scholar 

  12. Anderson, C. R., Cull-Candy, S. G. & Miledi, R. J. Physiol., Lond. 282, 219–242 (1978).

    Article  CAS  Google Scholar 

  13. Cull-Candy, S. G., Miledi, R. & Parker, I. J. Physiol., Lond. 321, 195–210 (1981).

    Article  CAS  Google Scholar 

  14. Stephenson, R. P. Br. J. Pharmac. 11, 379–393 (1956).

    CAS  Google Scholar 

  15. Hamill, O. P., Marty, A., Neher, E., Sakmann, B. & Sigworth, F. J. Pflügers Arch. ges. Physiol. 391, 85–100 (1981).

    Article  CAS  Google Scholar 

  16. Castillo, J. Del & Katz, B. Proc. R. Soc. B 146, 369–381 (1957).

    ADS  Google Scholar 

  17. Hamill, O. P. & Sakmann, B. Nature 294, 462–464 (1981).

    Article  ADS  CAS  Google Scholar 

  18. Auerbach, A. & Sachs, F. Biophys. J. 42, 1–10 (1983).

    Article  ADS  CAS  Google Scholar 

  19. Ogden, D. C. & Colquhoun, D. Pflügers Arch. ges. Physiol. 399, 246–248 (1983).

    Article  CAS  Google Scholar 

  20. Colquhoun, D. & Sakmann, B. in Single Channel Recording (eds Sakmann, B. & Neher, E.) (Plenum, New York, in the press).

  21. Sakmann, B. Fedn Proc. 37, 2654–2659 (1978).

    CAS  Google Scholar 

  22. Colquhoun, D., Large, W. A. & Rang, H. P. J. Physiol., Lond. 266, 361–395 (1975).

    Article  Google Scholar 

  23. Sakmann, B., Bormann, J. & Hamill, O. Cold Spring Harb. Symp. Quant. Biol. 48, (in the press).

  24. Ruff, R. L. J. Physiol., Lond. 264, 89–124 (1977).

    Article  CAS  Google Scholar 

  25. Ruff, R. L. Biophys. J. 37, 625–631 (1982).

    CAS  PubMed  PubMed Central  Google Scholar 

  26. Neher, E. J. Physiol., Lond. 339, 663–678 (1983).

    Article  CAS  Google Scholar 

  27. Colquhoun, D. in Cell Membrane Receptors for Drugs and Hormones (eds Straub, R. W. & Bolis, L. (Raven, New York, 1978).

    Google Scholar 

  28. Barlow, R. B., Thompson, G. M. & Scott, N. C. Br. J. Pharmac. 37, 555–584 (1969).

    Article  CAS  Google Scholar 

Download references

Author information

Authors and Affiliations


Rights and permissions

Reprints and Permissions

About this article

Cite this article

Gardner, P., Ogden, D. & Colquhoun, D. Conductances of single ion channels opened by nicotinic agonists are indistinguishable. Nature 309, 160–162 (1984).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing