Amplification of Neuromuscular Transmission by Postjunctional Folds

Previously, suggestions have been made that postjunctional folds at the vertebrate motor end plate might, in some way, serve to enhance neuromuscular transmission. This suggestion was examined quantitatively using a model junction with geometry similar to that seen in mammalian ‘fast twitch’ muscles...

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Bibliographic Details
Published in:Proceedings of the Royal Society. B, Biological sciences Biological sciences, 1994-12, Vol.258 (1353), p.321-326
Main Author: Martin, A. R.
Format: Article
Language:English
Subjects:
Animals
Capacitance
Cholinergic receptors
Depolarization
Electric Capacitance
Electric Impedance
Electrical Synapses - physiology
Mammals
Models, Biological
Muscle, Skeletal - physiology
Nerves
Receptors
Sodium
Sodium channels
Sodium Channels - physiology
Synapses
Transmitters
Vertebrates
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Summary:Previously, suggestions have been made that postjunctional folds at the vertebrate motor end plate might, in some way, serve to enhance neuromuscular transmission. This suggestion was examined quantitatively using a model junction with geometry similar to that seen in mammalian ‘fast twitch’ muscles. It was found that the depolarization produced at the top of an interfold by a quantum of acetylcholine is significantly greater than that produced in the absence of folds because of the series resistance of the interfold myoplasm. As a result, voltage-sensitive sodium channels in the postsynaptic membrane are activated more readily. In the model, activation of as few as four interfolds by eight quanta is sufficient for excitation to spread to the remainder of the muscle. With no folds, 19 quanta are required.
ISSN:0962-8452
1471-2954
DOI:10.1098/rspb.1994.0180