Skip to main content

Thank you for visiting nature.com. 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.

  • Letter
  • Published:

Active sodium transport by turtle colon via an electrogenic Na–K exchange pump

Abstract

Active sodium absorption by a variety of epithelia is abolished by ouabain, but the obligatory coupling between the movement of sodium and potassium expected from a basolateral (Na+ + K+) ATPase has not been convincingly demonstrated1. According to the model of Koefoed-Johnsen and Ussing2, the asymmetric cation selectivities of the apical and basolateral membranes prevent basolateral Na–K exchange from being expressed as opposing transmural ion flows. An additional consequence of this asymmetry is that the short-circuit current (ISC) cannot be identified with the current through the sodium–potassium pump. We used the polyene antibiotic, amphotericin-B, to reduce the resistance and the cation selectivity of the apical membrane of isolated turtle colon so that the basolateral membrane current could be dissected into two components: one through a barium-sensitive potassium channel and another which represents the current associated with ouabain-sensitive, electrogenic, Na–K exchange. Comparison of cation fluxes and short circuit current indicates that in these conditions active sodium absorption is entirely attributable to an electrogenic Na–K pump with a stoichiometry of approximately 3Na:2K.

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

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

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

Similar content being viewed by others

References

  1. Schultz, S. G. Membrane Transport Processes Vol. 1 (ed. Hoffman, J. F.) 213–117 (1978).

    Google Scholar 

  2. Koefoed-Johnson, V. & Ussing, H. H. Acta physiol. scand. 42, 298–308 (1958).

    Article  Google Scholar 

  3. Dawson, D. C. J. Membrane Biol. 37, 213–233 (1977).

    Article  CAS  Google Scholar 

  4. Thompson, S. M. & Dawson, D. C. J. Membrane Biol. 42, 357–374 (1978).

    Article  CAS  Google Scholar 

  5. Marty, A. & Finkelstein, A. J. gen Physiol. 65, 515–526 (1975).

    Article  CAS  Google Scholar 

  6. Cass, A. & Dalmark, M. Nature new Biol. 244, 47–49 (1973).

    Article  CAS  Google Scholar 

  7. Nielsen, R. J. Membrane Biol. 51, 161–184 (1979).

    Article  CAS  Google Scholar 

  8. Lewis, S. A., Eaton, D. C., Clausen, C. & Diamond, J. M. J. gen Physiol. 70, 427–440 (1977).

    Article  CAS  Google Scholar 

  9. Reuss, L. J. Membrane Biol. 42, 65–86 (1978).

    Article  Google Scholar 

  10. Nagel, W. Biochim. biophys. Acta 552, 346–357 (1979).

    Article  CAS  Google Scholar 

  11. Post, R. L. & Jolly, P. C. Biochim. biophys. Acta 25, 108–128 (1957).

    Article  Google Scholar 

  12. Hoffman, J. F., Kaplan, J. H. & Callahan, T. J. Fedn Proc. 38, 2440–2441 (1979).

    CAS  Google Scholar 

  13. Thomas, R. C. Physiol. Rev. 52, 563–594 (1972).

    Article  CAS  Google Scholar 

Download references

Author information

Authors and Affiliations

Authors

Rights and permissions

Reprints and permissions

About this article

Cite this article

Kirk, K., Halm, D. & Dawson, D. Active sodium transport by turtle colon via an electrogenic Na–K exchange pump. Nature 287, 237–239 (1980). https://doi.org/10.1038/287237a0

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/287237a0

This article is cited by

Comments

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.

Search

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