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Activation and blockade of mouse muscle nicotinic channels by antibodies directed against the binding site of the acetylcholine receptor.
Author(s) -
Bufler J,
Kahlert S,
Tzartos S,
Toyka K V,
Maelicke A,
Franke C
Publication year - 1996
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1996.sp021293
Subject(s) - acetylcholine receptor , nicotinic agonist , blockade , acetylcholine , nicotinic acetylcholine receptor , muscarinic acetylcholine receptor m5 , chemistry , receptor , pharmacology , ganglion type nicotinic receptor , alpha 4 beta 2 nicotinic receptor , binding site , neuroscience , muscarinic acetylcholine receptor m3 , biology , biochemistry
1. Using the patch‐clamp technique, we have found that mouse muscle nicotinic acetylcholine receptor (nAChR) channels can be activated by low concentrations of a monoclonal antibody (MoAb), referred to as WF6, which is directed against the acetylcholine (ACh) binding site. Similar effects were seen using IgG or F(ab)2 fragments from the sera of patients with myasthenia gravis (MG), which contain polyclonal anti‐nAChR antibodies. 2. The mean open times of MoAb and the slope conductance of single WF6‐activated single channels were similar to those of ACh‐activated channels under the same experimental conditions. 3. On outside‐out patches, single channel activity was elicited by MoAb WF6 and MG F(ab)2 fragments, and was blocked by (+)‐tubocurarine. We therefore concluded that MoAb WF6 and the MG F(ab)2 fragments activate the nAChR. 4. MoAb WF6 and MG F(ab)2 fragments blocked the current activated by pulsed application of 10(‐4) M ACh to a significant extent. The block was partly reversible. The rate constants for the binding and dissociation of MoAb WF6 from the receptor were determined quantitatively.