Ca2+-activated K+ permeability in human erythrocytes: modulation of single-channel events.
Elevated levels of intracellular Ca2+ activate a K+-selective permeability in the membrane of human erythrocytes. Currents through single channels were analysed in excised inside-out membrane patches. The effects of several ions that are known to inhibit K+ fluxes are described with respect to the single-channel events. The results suggest that the blocking ions can partly move into the channels (but cannot penetrate) and interact with other ions inside the pore. The reduction of single-channel conductance by Cs+, tetraethylammonium and Ba2+ and of single-channel activity by quinine and Ba2+ is referred to different rates of access to the channel. The concentration- and voltage-dependent inhibition by ions with measurable permeability (Na+ and Rb+) can be explained by their lower permeability, with single-file movement and ionic interactions inside the pore.
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R
Grygorczyk
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W
Schwarz
D002118:Calcium / Q000097:blood* / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007473:Ion Channels / Q000378:metabolism*; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D011188:Potassium / Q000097:blood*; D012964:Sodium / Q000494:pharmacology
D007473:Ion Channels; D012964:Sodium; D011188:Potassium; D002118:Calcium