Premium
Characterization of resting membrane potential and its electrogenic pump component in cultured chick myotubes
Author(s) -
Brodie Chaya,
Sampson S. R.
Publication year - 1989
Publication title -
international journal of developmental neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.761
H-Index - 88
eISSN - 1873-474X
pISSN - 0736-5748
DOI - 10.1016/0736-5748(89)90066-x
Subject(s) - ouabain , membrane potential , myogenesis , extracellular , biophysics , chemistry , membrane , transmembrane protein , myocyte , resting potential , biochemistry , biology , microbiology and biotechnology , in vitro , sodium , receptor , organic chemistry
The role of the electrogenic Na + ‐K + pump in the determination of the level of the resting membrane potential in cultured chick limb muscle was investigated. Transmembrane resting potential and ouabain‐sensitive 86 Rb‐uptake were measured in myotubes at different ages in culture from 2 to 10 days in vitro . Inhibition of the Na + ‐K + pump with ouabain prevented the developmental increase in membrane potential which normally follows fusion of myotubes (day 2–3). In mature myotubes, ouabain caused a dose‐related decrease in both membrane potential and 86 Rb‐uptake, with values for EC 50 and maximal effect being nearly the same on both variables. The decrease in membrane potential by ouabain, up to 20 mV maximum, occurred within 2–5 sec and was not accompanied by detectable changes in input resistance. Membrane potential was also reduced by a decrease in temperature of the recording medium and removal of extracellular K + , both of which reduce Na + ‐K + pump activity. We also found that the relation between membrane potential and extracellular K + concentration was completely attenuated by ouabain in the physiological range (2–10 mM). We conclude that the electrogenic Na + ‐K + pump plays an important role in the determination of the resting membrane potential of chick myotubes and that regulation of its level is not entirely explained by the diffusion potential hypothesis.