| Some properties of acetylcholine receptors in human cultured myotubes. | |
MedLine Citation:
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PMID: 2408280 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The distribution and single channel properties of acetylcholine (ACh) receptors in human myotubes grown in tissue culture have been examined. Radioautography of myotubes labelled with [125I]alpha-bungarotoxin showed that ACh receptors are distributed uniformly over the myotube surface at a density of 3.9 +/- 0.5 receptors per square micrometre. Accumulations of ACh receptors (hot spots) were found rarely. The conductance and kinetics of ACh-activated channels were investigated with the patch-clamp technique. Cell-attached membrane patches were used in all experiments. A single channel conductance in the range 40-45 pS was calculated. No sublevels of conductance (substates) of the activated channel were observed. The distribution of channel open-times varied with ACh concentration. With 100 nM ACh, the distribution was best fitted by the sum of two exponentials, whereas with 1 microM ACh a single exponential could be fitted. The mean channel open-time at the myotube resting potential (ca. -70 mV, 22 degrees C) was 8.2 ms. The distribution of channel closed-times was complex at all concentrations of ACh studied (100 nM to 10 microM). With desensitizing doses of ACh (10 microM), channel openings occurred in obvious bursts; each burst usually appeared as part of a 'cluster' of bursts. Both burst duration and mean interval between bursts increased with membrane hyperpolarization. Individual channel open-times and burst durations showed similar voltage dependence (e-fold increase per 80 mV hyperpolarization), whereas both the channel closed-times within a burst and the number of openings per burst were independent of membrane potential. |
Authors:
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D J Adams; S Bevan |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Proceedings of the Royal Society of London. Series B, Containing papers of a Biological character. Royal Society (Great Britain) Volume: 224 ISSN: 0080-4649 ISO Abbreviation: Proc. R. Soc. Lond., B, Biol. Sci. Publication Date: 1985 Apr |
Date Detail:
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Created Date: 1985-06-26 Completed Date: 1985-06-26 Revised Date: 2007-04-30 |
Medline Journal Info:
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Nlm Unique ID: 7505889 Medline TA: Proc R Soc Lond B Biol Sci Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 183-96 Citation Subset: IM |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Acetylcholine
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physiology Cell Compartmentation Cells, Cultured Electric Conductivity Humans Ion Channels / physiology Membrane Potentials Muscles / physiology, ultrastructure Receptors, Cholinergic / physiology* Sarcolemma / physiology*, ultrastructure |
| Chemical | |
Reg. No./Substance:
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0/Ion Channels; 0/Receptors, Cholinergic; 51-84-3/Acetylcholine |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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