ISSN:
1432-2013
Keywords:
Skeletal muscle
;
Two stable potential levels
;
Inward rectifier K channel
;
Cevadine
;
Slow membrane potential oscillation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Applying conventional microelectrode technique the anomalous behaviour of membrane potential in response to changes in [K+]o was demonstrated in normal and cevadine-treated muscles bathed in Cl−-free medium. Partial repolarization of the cevadine-depolarized membrane and reappearance of the slow membrane potential oscillation (SMPO) were induced by elevating [K+]o from 2.5 mM to 10–20 mM. Both effects were reversed by return to 2.5 mM [K+]o. The K-induced repolarization was markedly reduced by 20 mM Cs+, but not by 0.1 mM ouabain, 1 mM 4-aminopyridine, or 1 mM diethyl-pyrocarbonate. The elevation of [K+]o failed to repolarize muscle fibers that had been depolarized only to a small extent. No K-induced repolarization has been observed in Cl−-containing fluid. In cevadine-free experiments the omission of potassium from the extracellular space in Cl−-free solution hyperpolarized some of the fibers, while depolarized others. Strong electrical stimuli applied in zero K-zero Cl solution turned all the fibers into depolarized state; on returning to 2.5 mM [K+]o complete repolarization was achieved in most of the fibers. It has been concluded that the paradox response of the muscle membrane to changes in [K+]o can be attributed to the K-dependent conductance changes of the inward rectifier K channel providing an explanation for the plateau-formation of SMPO and for the existence of two stable levels of membrane potential of the skeletal muscle bathed in Cl−-free medium.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00580958
Permalink
