title: Investigations on the control of ion transport in human erythrocytes. II. Influence of transmembrane potential, exterior surface potential and intracellular pH on the 22Na efflux.
abstract: The rate constant of the Na+ efflux of human erythrocytes in isotonic solutions of various ionic strength varied over NaCl concentration was measured. The Na+ efflux remained constant over a wide range of ionic strength. Only under conditions where the transmembrane potential was near O mV, a local minimum could be detected. The rate constant of the ouabain-insensitive part of the Na+ efflux exhibited a strong increase at reduced exterior ionic strength. When reducing the extracellular NaCl concentration and at the same time equivalently increasing the extracellular KCl concentration in solutions of physiological ionic strength, a reduction of the rate constant of the Na+ efflux was found. It was established that an increase of the intracellular pH increases the rate constant of the Na+ efflux. A change of transmembrane potential from -7 to 52 mV at constant intracellular pH had no influence on the Na+ efflux. The change of the exterior surface potential of erythrocytes by preincubation with neuraminidase had no influence on the Na+ efflux in the range of the ionic strength studied.
mesh_terms: D004912:Erythrocytes / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007474:Ion Exchange; D008564:Membrane Potentials; D012964:Sodium / Q000378:metabolism*; D012975:Sodium Isotopes
chemical_list: D012975:Sodium Isotopes; D012964:Sodium