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


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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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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