Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Sodium uptake across the apical border of the isolated turtle colon: Confirmation of the two-barrier model

  • 24 Accesses

  • 18 Citations

Summary

The initial rate of Na uptake by the turtle colon from the mucosal bathing solution consists of two operationally distinct components. One component is a linear function of mucosal Na concentration, is unaffected by amiloride, and appears to represent Na uptake into the paracellular shunt path. The major component of Na uptake is abolished by amiloride and is virtually equal to the short-circuit current over a wide range of. mucosal Na concentrations, suggesting that this portion of Na uptake represents Na movement into Na-transporting cells of the colon. The amiloride-sensitive component of Na uptake, at low mucosal Na concentrations, was unaffected if net Na transport was abolished by ouabain. Similarly, at low mucosal Na concentrations the amiloride-sensitive conductance of the colon was identical in the presence and in the absence of net Na transport.

These results show that the isolated turtle colon behaves, as two distinct barriers to transmural Na transport, an apical barrier blocked by amiloride and a more basal-lying barrier where active, transmural Na transport is blocked by ouabain. In addition, these experiments appear to provide the first unambiguous demonstration that the initial-rate isotope uptake technique can provide adirect measure of the properties of the amiloridesensitive barrier to transmural Na movement, presumably the apical membranes of the Na-transporting cells. The results are consistent with the notion that the rate of transmural active Na transport and the conductance of the active Na-transport path are determined by the properties of the apical membrane.

This is a preview of subscription content, log in to check access.

References

  1. 1.

    Biber, T. U. L. 1971. Effect of changes in transepithelial transport on the uptake of sodium across the outer border of frog skin.J. Gen. Physiol. 58: 131

  2. 2.

    Biber, T. U. L., Curran, P. F. 1970. Direct measurement of uptake of sodium at the outer surface of frog skin.J. Gen. Physiol. 56: 83

  3. 3.

    Cereijido, M., Curran, P. F. 1965. Intracellular electrical potentials in frog skin.J. Gen. Physiol. 48: 543

  4. 4.

    Civan, M. M., Frazier, H. S. 1968. The site of the stimulatory actions of vasopressin on sodium transport in the toad bladder.J. Gen. Physiol. 51: 589

  5. 5.

    Dawson, D. C. 1977. Na and Cl transport across the isolated turtle colon: Parallel pathways for transmural ion movement.J. Membrane Biol. 37: 213

  6. 6.

    Dawson, D. C., Curran, P. F. 1976. Sodium transport by the colon ofBufo marinus: Na uptake across the mucosal border.J. Membrane Biol. 28: 295.

  7. 7.

    Di Bona, D. R., Civan, M. M. 1973. Pathways for movements of ions and water across toad urinary bladder. I. Anatomic site of transepithelial shunt pathways.J. Membrane Biol. 12: 101

  8. 8.

    Erlij, D., Smith, M. N. 1973. Sodium uptake by frog skin and its modification by inhibitors of transepithelial sodium transport.J. Physiol. (London) 228: 221

  9. 9.

    Finn, A. L. 1975. Action of ouabain on sodium transport in toad urinary bladder. Evidence for two pathways for sodium entry.J. Gen. Physiol. 65: 503

  10. 10.

    Frazier, H. S. 1962. The electrical potential profile of the isolated toad bladder.J. Gen. Physiol. 45: 515

  11. 11.

    Frizzell, R. A., Turnheim, K. 1978. Ion transport by rabbit colon II: Unidirectional sodium influx and the effects of amphotericin B and amiloride.J. Membrane Biol. 40: 193

  12. 12.

    Helman, S. I., Fisher, R. S. 1977. Microelectrode studies of the active Na transport pathway of frog skin.J. Gen. Physiol. 69: 571

  13. 13.

    Helman, S. I., Miller, D. A. 1973. Edge damage effect on electrical measurements of frog skin.Am. J. Physiol. 225: 972

  14. 14.

    Koefoed-Johnsen, V., Ussing, H. H. 1958. The nature of the frog skin potential.Acta. Physiol. Scand. 42: 298

  15. 15.

    Lewis, S. 1977. A reinvestigation of the function of the mammalian urinary bladder.Am. J. Physiol. 232:F187.

  16. 16.

    Lewis, S. A., Eaton, D. C., Diamond, J. M. 1976. The mechanism of Na+ transport by rabbit urinary bladder.J. Membrane Biol. 28: 41

  17. 17.

    Lindemann, B., Van Dreissche, W. 1978. The mechanism of Na uptake through Naselective channels in the epithelium of frog skin.In: Membrane Transport Processes. J. F. Hoffman, editor Vol. 1. p. 155. Raven Press, New York

  18. 18.

    MacKnight, A. D. C., Civan, M. M., Leaf, A. 1975. Some effects of ouabain on cellular ions and water in epithelial cells of the toad bladder.J. Membrane Biol. 20: 387

  19. 19.

    Mills, J. W., Ernst, S. A., DiBona, D. R. 1977. Localization of Na+ pump sites in frog skin.J. Cell. Biol. 73: 88

  20. 20.

    Moreno, J. H., Reisen, I. L., Rodriguez Boulán, E., Rotunno, C. A., Cereijido, M. 1973. Barriers to sodium movement across frog skin.J. Membrane Biol. 11: 99

  21. 21.

    Nagle, W. 1976. The intracellular electrical potential profile of the frog skin epithelium.Pfluegers Arch. 365: 135

  22. 22.

    Rick, R., Dörge, A., Nagel, W. 1975. Influx and efflux of sodium at the outer surface of frog skin.J. Membrane Biol. 22: 183

  23. 23.

    Schultz, S. G., Curran, P. F., Chez, R. A., Fuisz, R. E. 1967. Alanine and sodium fluxes across mucosal border of rabbit ileum.J. Gen. Physiol. 50: 1241

  24. 24.

    Schultz, S. G., Frizzell, R. A., Nellans, H. N. 1977. Active sodium transport and the electrophysiology of rabbit colon.J. Membrane Biol. 33: 351

  25. 25.

    Turnheim, K., Frizzell, R. A., Schultz, S. G. 1977. Negative feedback between cell Na and the amiloride-sensitive entry step in rabbit colon.Physiologist 20: 96

  26. 26.

    Turnheim, K., Frizzell, R. A., Schultz, S. G. 1977. Effect of anions on amiloride-sensitive, active sodium transport across rabbit colon,in vitro.J. Membrane Biol. 37: 63

Download references

Author information

Correspondence to David C. Dawson.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Thompson, S.M., Dawson, D.C. Sodium uptake across the apical border of the isolated turtle colon: Confirmation of the two-barrier model. J. Membrain Biol. 42, 357–374 (1978). https://doi.org/10.1007/BF01870356

Download citation

Keywords

  • Ouabain
  • Apical Membrane
  • Amiloride
  • Bathing Solution
  • Sodium Uptake