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PROPERTIES OF THE CELL MEMBRANE OF DEVELOPING SKELETAL MUSCLE FIBRES IN CULTURE AND ITS SENSITIVITY TO ACETYLCHOLINE
Author(s) -
Dryden William F.,
Erulkar Solomon D.,
Haba Gabriel
Publication year - 1974
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1974.tb00559.x
Subject(s) - depolarization , myogenesis , myocyte , acetylcholine , membrane potential , medicine , hyperpolarization (physics) , endocrinology , biophysics , chemistry , resting potential , biology , organic chemistry , nuclear magnetic resonance spectroscopy
SUMMARY 1. The relationship between determinants of membrane potential has been studied during myogenesis in culture. 2. Myoblasts obtained from 11‐day chick embryo musculature were cultured and intracellular records were made from myoblasts and developing unstriated and striated myotubes. 3. Resting membrane potentials increased with time of culture until values equivalent to those obtained from fully developed striated muscle fibres were reached after about 20 days in culture. 4. High concentrations of potassium added to the medium failed to affect significantly the resting membrane potentials in myoblasts and myotubes up to 10 days in culture. Changes in external sodium had little effect on values of potentials from myotubes and cells up to 4 days in culture, but removal of sodium after 5 and 6 days in culture caused depolarization. 5. Electrolyte distributions determined for myoblasts and myotubes 4 days after fusion showed no significant change in potassium content, whereas the sodium concentration fell significantly. 6. Acetylcholine applied by microinjection caused two types of response from myoblasts depending upon the level of the resting membrane potential: when the potential was less than —7 mV, hyperpolarization occurred; when it was greater than this value, depolarization occurred. 7. Depolarizing responses to acetylcholine application were regularly obtained from myotubes with resting membrane potentials greater than —7 mV. 8. The responses to acetylcholine could be blocked by d ‐tubocurarine in the medium; tetramethylammonium (a nicotinic agonist) acted similarly to acetylcholine, but bethanecol (a muscarinic agonist) had no effect.