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Blockade of acetylcholine receptors by cobra toxin: electrophysiological studies

Lester, H. A. (1972) Blockade of acetylcholine receptors by cobra toxin: electrophysiological studies. Molecular Pharmacology, 8 (6). pp. 623-631. ISSN 0026-895X.

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Microelectrode techniques were used to investigate the manner in which a pure polypeptide toxin from cobra venom blocks transmission at the frog myoneural junction. At concentrations of 16-114 nM, the toxin causes an irreversible exponential decline in the amplitude of the end plate potential as a result of a decrease in the sensitivity of the postsynaptic receptors for acetylcholine. Other processes, such as spontaneous and impulse-evoked acetylcholine release, acetylcholinesterase activity, and passive electrical properties of the muscle fiber membrane, remain unaffected. The rate constant for inactivation of receptors increases linearly with toxin concentration. The constant of proportionality probably describes the binding of toxin to the receptor and equals 1.5 x 10⁵ M⁻¹ sec⁻¹. Certain complications in these experiments arise because diffusion barriers limit the access of toxin molecules to the receptors.

Item Type:Article
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Lester, H. A.0000-0002-5470-5255
Additional Information:© 1972 by Academic Press. (Received March 14, 1972) I am indebted to F. A. Dodge, Jr., and to F. Ratliff, my predoctoral advisors, for their unfailing guidance. I also thank C. M. Connelly, H. K. Hartline, A. Mauro, and D. Mauzerall for advice. H. P. Rang helped with preparation of the manuscript. These studies were supported by Grant EY 188 from the National Institutes of Health, Grant GB 6540 from the National Science Foundation, and a Predoctoral Fellowship from the National Institutes of Health, United States Public Health Service.
Funding AgencyGrant Number
NSFGB 6540
NIH Predoctoral FellowshipUNSPECIFIED
Issue or Number:6
Record Number:CaltechAUTHORS:20201005-113628628
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Official Citation:Blockade of Acetylcholine Receptors by Cobra Toxin: Electrophysiological Studies H. A. LESTER Molecular Pharmacology November 1, 1972, 8 (6) 623-631
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105790
Deposited By: George Porter
Deposited On:05 Oct 2020 20:42
Last Modified:05 Oct 2020 20:42

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