The Journal of Membrane Biology

, Volume 102, Issue 1, pp 35–48

Na+/H+ exchange in ehrlich ascites tumor cells: Activation by cytoplasmic acidification and by treatment with cupric sulphate

  • Birte Kramhøft
  • Ian H. Lambert
  • Else K. Hoffmann
Articles

DOI: 10.1007/BF01875351

Cite this article as:
Kramhøft, B., Lambert, I.H. & Hoffmann, E.K. J. Membrain Biol. (1988) 102: 35. doi:10.1007/BF01875351

Summary

Exposure of Ehrlich cells to isotonic Na+-propionate medium induces a rapid cell swelling. This treatment is likely to impose an acid load on the cells. Cell swelling is absent in K+-propionate medium but may be induced by the ionophore nigericin, which mediates K+/H+ exchange. Cell swelling in Na+-propionate medium is blocked by amiloride, but an alternative pathway is introduced by addition of the ionophore monensin, which mediates Na+/H+ exchange. Consequently, swelling of Ehrlich cells in Na+-propionate medium is due to the operation of an amiloride-sensitive, Na+-specific mechanism. It is concluded that this mechanism is a Na+/H+ exchange system, activated by cytoplasmic acidification. We have previously demonstrated that the heavy metal salt CuSO4 in micromolar concentrations inhibits regulatory volume decrease (RVD) of Ehrlich cells following hypotonic swelling. The present work shows that CuSO4 inhibits RVD as a result of a net uptake of sodium, of which the major part is sensitive to amiloride. Measurements of intracellular pH show that CuSO4 causes significant cytoplasmic alkalinization, which is abolished by amiloride. Concomitantly, CuSO4 causes an amiloride-sensitive net proton efflux from the cells. The combined results confirm that a Na+/H+ exchange system exists in Ehrlich cells and demonstrate that the heavy metal salt CuSO4 activates this Na+/H+ exchange system.

Key Words

Ehrlich ascites tumor cells pH regulation Na+/H+ exchange volume regulation hypotonic shock cupric sulphate cytoplasmic acidification phorbol ester TPA 

Copyright information

© Springer-Verlag New York Inc. 1988

Authors and Affiliations

  • Birte Kramhøft
    • 1
  • Ian H. Lambert
    • 1
  • Else K. Hoffmann
    • 1
  1. 1.Institute of Biological Chemistry AAugust Krogh InstituteCopenhagen ØDenmark

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