Acetylcholine receptor channels on adult mouse skeletal muscle are functionally identical in synaptic and nonsynaptic membrane

Paul Brehm, R. Kullberg

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

It has been proposed that acetylcholine receptor channels exhibit a functionally distinct 'junctional' form at the region of synaptic contact between nerve and muscle. As a direct test of this idea, we compared acetylcholine-activated single-channel currents from synaptic membrane to those obtained from nonsynaptic sites on freshly dissociated adult mouse toe muscle. We observed, at locations along the entire length of the cell, openings by a channel with a high conductance (70 pS) and brief open time (~ 2 msec), characteristic of the classical 'junctional type' of actylcholine receptor. In 8 out of 10 synaptic and in 9 out of 19 nonsynaptic recordings, we also observed infrequent openings by a low-conductance (45-pS) channel traditionally associated only with nonsynaptic regions. In these recordings the low-conductance acetycholine receptor channel averaged only 3% of the total channel openings. Comparisons of synaptic and nonsynaptic patches indicated no trend toward an increased proportion of low-conductance channel openings with increased distance from the synapse. These findings support the view that the functional properties of the acetylcholine receptor channel do not depend on proximity to the synapse in innervated mouse skeletal muscle.

Original languageEnglish (US)
Pages (from-to)2550-2554
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume84
Issue number8
StatePublished - 1987
Externally publishedYes

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Synaptic Membranes
Cholinergic Receptors
Synapses
Skeletal Muscle
Muscles
Toes
Acetylcholine

ASJC Scopus subject areas

  • General
  • Genetics

Cite this

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abstract = "It has been proposed that acetylcholine receptor channels exhibit a functionally distinct 'junctional' form at the region of synaptic contact between nerve and muscle. As a direct test of this idea, we compared acetylcholine-activated single-channel currents from synaptic membrane to those obtained from nonsynaptic sites on freshly dissociated adult mouse toe muscle. We observed, at locations along the entire length of the cell, openings by a channel with a high conductance (70 pS) and brief open time (~ 2 msec), characteristic of the classical 'junctional type' of actylcholine receptor. In 8 out of 10 synaptic and in 9 out of 19 nonsynaptic recordings, we also observed infrequent openings by a low-conductance (45-pS) channel traditionally associated only with nonsynaptic regions. In these recordings the low-conductance acetycholine receptor channel averaged only 3{\%} of the total channel openings. Comparisons of synaptic and nonsynaptic patches indicated no trend toward an increased proportion of low-conductance channel openings with increased distance from the synapse. These findings support the view that the functional properties of the acetylcholine receptor channel do not depend on proximity to the synapse in innervated mouse skeletal muscle.",
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AU - Brehm, Paul

AU - Kullberg, R.

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N2 - It has been proposed that acetylcholine receptor channels exhibit a functionally distinct 'junctional' form at the region of synaptic contact between nerve and muscle. As a direct test of this idea, we compared acetylcholine-activated single-channel currents from synaptic membrane to those obtained from nonsynaptic sites on freshly dissociated adult mouse toe muscle. We observed, at locations along the entire length of the cell, openings by a channel with a high conductance (70 pS) and brief open time (~ 2 msec), characteristic of the classical 'junctional type' of actylcholine receptor. In 8 out of 10 synaptic and in 9 out of 19 nonsynaptic recordings, we also observed infrequent openings by a low-conductance (45-pS) channel traditionally associated only with nonsynaptic regions. In these recordings the low-conductance acetycholine receptor channel averaged only 3% of the total channel openings. Comparisons of synaptic and nonsynaptic patches indicated no trend toward an increased proportion of low-conductance channel openings with increased distance from the synapse. These findings support the view that the functional properties of the acetylcholine receptor channel do not depend on proximity to the synapse in innervated mouse skeletal muscle.

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