Desensitization is a property of the cholinergic binding region of the nicotinic acetylcholine receptor, not of the receptor-integral ion channel

The reversible acetylcholine esterase inhibitor (−)-physostigmine (eserine) is the prototype of a new class of nicotinic acetylcholine receptor (nAChR) activating ligands: it induces cation fluxes into nAChR-rich membrane vesicles from Torpedo marmorala electric tissue even under conditions of antag...

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Bibliographic Details
Published in:FEBS letters 1991-02, Vol.279 (2), p.216-218
Main Authors: Kuhlmann, Jürgen, Okonjo, Kehinde O., Maelicke, Alfred
Format: Article
Language:English
Subjects:
acetylcholine
Acetylcholine - pharmacology
acetylcholine esterase
Acetylcholine-gated cation channel
ACh
AChE
Animals
Anticholinesterase
Binding Sites
Biological and medical sciences
Bungarotoxins - pharmacology
Carbamate
Cell receptors
Cell structures and functions
Cesium - metabolism
Desensitization
electric organs
Eserine
Freshwater
Fundamental and applied biological sciences. Psychology
In Vitro Techniques
Ion Channels - drug effects
Ion flux
Molecular and cellular biology
Monoamines receptors (catecholamine, serotonine, histamine, acetylcholine)
nAChR
neurophysiology
neurotransmitters
Nicotinic acetylcholine receptor
Physostigmine
Physostigmine - pharmacology
receptors
Receptors, Nicotinic - drug effects
Torpedo
Torpedo marmorata
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Summary:The reversible acetylcholine esterase inhibitor (−)-physostigmine (eserine) is the prototype of a new class of nicotinic acetylcholine receptor (nAChR) activating ligands: it induces cation fluxes into nAChR-rich membrane vesicles from Torpedo marmorala electric tissue even under conditions of antagonist blocked acetylcholine binding sites (Okonjo, Kuhlmann, Maclicke, Neuron, in press). This suggests that eserine exerts its channel-activating property via binding sites at the nAChR separate from those of the natural transmitter. We now report that eserine can activate the channel even when the receptor has been preincubated (desensitized) with elevated concentrations of acetylcholine. Thus the conformational state of the receptor corresponding to desensitization is confined to the transmitter binding region, leaving the channel fully activatable — albeit only from other than the transmitter binding site(s).
ISSN:0014-5793
1873-3468
DOI:10.1016/0014-5793(91)80152-S