The cell model of the electrolyte transport mechanisms for cultured human colonocytes. Electromotive forces of the cellular pathways

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The purpose of this work was to explain the chloride secretory model of the human colonocytes in terms of the equivalent electromotive forces and the relative apical ionic permeabilities using a conventional micro-electrode technique and different ion-substitution experiments. Both equivalent electromotive forces (for apical and basolateral membranes: Ea = -47.7±5.1 mV and Eb = -65.2±2.9 mV, respectively) depend strongly on the external K+ concentration. The most important conclusion is that both cell membrane potentials are largely dominated by a K+ permeability. The apical membrane has low Na+ and Cl- permeabilities in non-stimulated conditions (PNa/PK = 0.06±0.01 and PCl/PK = 0.23±0.09). An interesting response was found for the basolateral Na+ substitutions. Lowering the basolateral Na+ concentration at 1 mM we have seen a slow, but large depolarization of the cell membrane potential of about 30 mV. We think that this is mostly caused by the presence of the basolateral Na+/H+ exchanger mechanism for the intracellular pH regulation. The Na+/K+ pump has a significant contribution to the basolateral electromotive force. The basolateral membrane has also a Cl- permeability in non-stimulated conditions, but the basolateral Na+ permeability is undetectable.

Original languageEnglish (US)
Pages (from-to)169-176
Number of pages8
JournalBioelectrochemistry and Bioenergetics
Issue number2
StatePublished - Jan 1998



  • Apical ionic permeabilities
  • Basolateral Na/H exchanger
  • Cell model
  • Chloride secretion
  • Human colon epithelial cells
  • Ion-substitution experiments

ASJC Scopus subject areas

  • Biophysics
  • Physical and Theoretical Chemistry
  • Electrochemistry

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