The Journal of Membrane Biology

, Volume 88, Issue 1, pp 67–75 | Cite as

Single-file diffusion through the Ca2+-activated K+ channel of human red cells

  • Bent Vestergaard-Bogind
  • Per Stampe
  • Palle Christophersen
Articles

Summary

The ratio between the unidirectional fluxes through the Ca2+-activated K+-specific ion channel of the human red cell membrane has been determined as a function of the driving force (V m -E K ). Net effluxes and42K influxes were determined during an initial period of ∼90 sec on cells which had been depleted of ATP and loaded with Ca. The cells were suspended in buffer-free salt solutions in the presence of 20 μm of the protonophore CCCP, monitoring in this way changes in membrane potential as changes in extracellular pH. (V m -EK) was varied at constantEK by varying the Nernst potential and the conductance of the anion and the conductance of the potassium ion. In another series of experimentsEK was varied by suspending cells in salt solutions with different K+ concentrations. At high extracellular K+ concentrations both of the unidirectional fluxes were determined as42K in- and effluxes in pairs of parallel experiments. Within a range of (V m -EK) of −6 to 90 mV the ratio between the unidirectional fluxes deviated strongly from the values predicted by Ussing's flux ratio equation. The Ca2+-activated K+ channel of the human red cell membrane showed single-file diffusion with a flux ratio exponentn of 2.7. The magnitude ofn was independent of the driving force (V m -EK), independent ofV m and independent of the conductancegK.

Key Words

single-file diffusion Ca2+-activated K+ channel human erythrocytes 

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References

  1. Begenisich, T., De Weer, P. 1980. Potassium flux ratio in voltage-clamped squid axons.J. Gen. Physiol. 76:83–98CrossRefPubMedGoogle Scholar
  2. Ferreira, H.G., Lew, V.L. 1976. Use of ionophore A23187 to measure cytoplasmic Ca buffering and activation of the Ca pump by internal Ca.Nature (London) 259:47–49Google Scholar
  3. Gárdos, G. 1958. The function of calcium in the potassium permeability of human erythrocytes.Biochim. Biophys. Acta 30:653–654PubMedGoogle Scholar
  4. Grygorczyk, R., Schwarz, W. 1983. Properties of the Ca2+-activated K+ conductance of human red cells as revealed by the patch-clamp technique.Cell Calcium 4:499–510CrossRefPubMedGoogle Scholar
  5. Hamill, O.P. 1981. Potassium channel currents in human red blood cells.J. Physiol. (London) 319:97P-98PGoogle Scholar
  6. Hille, B., Schwarz, W. 1978. Potassium channels as multi-ion single-file pores.J. Gen. Physiol. 72:409–442PubMedGoogle Scholar
  7. Hodgkin, A.L., Huxley, A.F. 1952. The components of membrane conductance in the giant axon ofLoligo.J. Physiol. (London) 116:449–472Google Scholar
  8. Hodgkin, A.L., Keynes, R.D. 1955. The potassium permeability of a giant nerve fibre.J. Physiol. (London) 128:61–88Google Scholar
  9. Hoffman, J.F., Yingst, D.R., Goldinger, J.M., Blum, R.M., Knauf, P.A. 1980. On the mechanism of Ca-dependent K transport in human red blood cells.In: Membrane Transport in Erythrocytes: Alfred Benzon Symp. 14. U.V. Lassen, H.H. Ussing, and J.O. Wieth, editors. pp. 178–195. Munksgaard. CopenhagenGoogle Scholar
  10. Horowicz, P., Gage, P.W., Eisenberg, R.S. 1968. The role of the electrochemical gradient in determining potassium fluxes in frog striated muscle.J. Gen. Physiol. 51:193s-203sPubMedGoogle Scholar
  11. Knauf, P.A., Fuhrmann, G.F., Rothstein, S., Rothstein, A. 1977. The relationship between anion exchange and net anion flow across the human red blood cell membrane.J. Gen. Physiol. 69:363–386PubMedGoogle Scholar
  12. Kregenow, F.M., Hoffman, J.F. 1972. Some kinetic and metabolic characteristics of calcium-induced potassium transport in human red cells.J. Gen. Physiol. 60:406–429PubMedGoogle Scholar
  13. Latorre, R., Miller, C. 1983. Conduction and selectivity in potassium channels.J. Membrane Biol. 71:11–30Google Scholar
  14. Latorre, R., Vergara, C., Hidalgo, C. 1981. Reconstitution in planar lipid bilayers of a Ca2+-dependent K+-channel from transverse tubule membranes isolated from rabbit skeletal muscle.Proc. Natl. Acad. Sci. USA 79:805–809Google Scholar
  15. Lew, V.L., Brown, A.M. 1979. Experimental control and assessment of free and bound calcium in the cytoplasm of intact mammalian red cells.In: Detection and Measurement of Free Ca2+ in Cells. C.C. Ashley, and A.K. Campbell editors. pp. 423–432. Elsevier/North-Holland Biomedical, AmsterdamGoogle Scholar
  16. Macey, R.I., Adorante, J.S., Orme, F.W. 1978. Erythrocyte membrane potentials determined by hydrogen ion distribution.Biochim. Biophys. Acta 512:284–295PubMedGoogle Scholar
  17. Meech, R.W., Standen, N.B. 1975. Potassium activation inHelix aspersa neurons under voltage clamp: A component mediated by calcium influx.J. Physiol. (London) 249:211–239Google Scholar
  18. Sjodin, R.A. 1965. The potassium flux ratio in skeletal muscle as a test for independent ion movement.J. Gen. Physiol. 48:777–795PubMedGoogle Scholar
  19. Spalding, B.C., Senyk, O., Swift, J.G., Horowicz, P. 1981. Unidirectional flux ratio for potassium ions in depolarized frog skeletal muscle.Am. J. Physiol. 241:c68-c75Google Scholar
  20. Stampe, P., Vestergaard-Bogind, B. 1985. The Ca2+-sensitive K+-conductance of the human red cell membrane is strongly dependent on cellular pH.Biochim. Biophys. Acta 815:313–321PubMedGoogle Scholar
  21. Ussing, H.H. 1949. The distinction by means of tracers between active transport and diffusion.Acta Physiol. Scand. 19:43–56Google Scholar
  22. Vestergaard-Bogind, B. 1983. Spontaneous inactivation of the Ca2+-sensitive K+-channels of human red cells at high intracellular Ca2+ activity.Biochim. Biophys. Acta 730:285–294PubMedGoogle Scholar
  23. Vestergaard-Bogind, B., Stampe, P. 1984.Trans tocis proton concentration gradients accelerate ionophore A23187-mediated net fluxes of Ca2+ across the human red cell membrane.Biochim. Biophys. Acta 775:328–340PubMedGoogle Scholar
  24. Yingst, D.R., Hoffman, J.F. 1984. Ca-induced K transport in human red blood cell ghosts containing Arsenazo III.J. Gen. Physiol. 83:19–45CrossRefPubMedGoogle Scholar

Copyright information

© Springer-Verlag 1985

Authors and Affiliations

  • Bent Vestergaard-Bogind
    • 1
  • Per Stampe
    • 1
  • Palle Christophersen
    • 1
  1. 1.Zoophysiological Laboratory B, August Krogh InstituteUniversity of CopenhagenCopenhagen 0Denmark

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