Pflügers Archiv

, Volume 447, Issue 4, pp 416–425

In skeletal muscle the relaxation of the resting membrane potential induced by K+ permeability changes depends on Cl transport

Ion Channels, Transporters

DOI: 10.1007/s00424-003-1165-1

Cite this article as:
Geukes Foppen, R.J. Pflugers Arch - Eur J Physiol (2004) 447: 416. doi:10.1007/s00424-003-1165-1

Abstract

In resting skeletal muscle the potassium permeability is determined by the permeability of the inwardly potassium rectifier. Continuous resting membrane potential measurements are done to follow the relaxation of the membrane potential upon changes in potassium permeability. Inhibition of the inwardly potassium rectifier, by extracellular application of 80 µM Ba2+, causes the cell to depolarize with mean time constants as follows: in control 127±7 s (n=23), in the presence of bumetanide, as an inhibitor of the Na+/K+/2Cl cotransporter, 182±23 s (n=7), in hypertonic media (340 mosmol/kg) 90.4±5 s (n=7) and in reduced chloride medium 64±8 s (n=5). The depolarizing relaxation of the membrane potential induced by reduction of extracellular potassium produces similar results. These time constants are at least three orders of magnitude slower than the time constants reported in the literature for the inhibition of the inwardly potassium rectifier. Chloride transport affects the relaxation of the membrane potential. A further characterization of chloride transport is done by following the relaxation of the membrane potential upon application of chloride transport modulators. It is argued that the electroneutral cotransporter, for which a flux was preliminarily estimated of 13.4 pmol cm−2 s−1, has a considerable role in the processes related to the resting membrane potential.

Keywords

Barium Bumetanide Inwardly potassium rectifier Membrane potential Na+/K+/2Cl cotransporter Skeletal muscle 

Copyright information

© Springer-Verlag  2003

Authors and Affiliations

  1. 1.Swammerdam Institute for Life Sciences, Faculty of Natural Sciences, Mathematics and InformaticsUniversity of AmsterdamAmsterdamThe Netherlands

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