Lester, Henry A. and Changeux, Jean-Pierre and Sheridan, Robert E. (1975) Conductance increases produced by bath application of cholinergic agonists to Electrophorus electroplaques. Journal of General Physiology, 65 (6). pp. 797-816. ISSN 0022-1295 http://resolver.caltech.edu/CaltechAUTHORS:LESjgp75
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When solutions containing agonists are applied to the innervated face of an Electrophorus electroplaque, the membrane's conductance increases. The agonist-induced conductance is increased at more negative membrane potentials. The "instantaneous" current-voltage curve for agonist-induced currents is linear and shows a reversal potential near zero mV; chord conductances, calculated on the basis of this reversal potential, change epsilon-fold for every 62-mV change in potential when the conductance is small. Conductance depends non- linearly on small agonist concentrations; at all potentials, the dose-response curve has a Hill coefficient of 1.45 for decamethonium (Deca) and 1.90 for carbamylcholine (Carb). With agonist concentrations greater than 10^(-4) M Carb or 10^(-5) M Deca, the conductance rises to a peak 0.5-1.5 min after introduction of agonist, then declines with time; this effect resembles the "desensitization" reported for myoneural junctions. Elapid alpha-toxin, tubocurarine, and desensitization reduce the conductance without changing the effects of potential; the apparent dissociation constant for tubocurarine is 2 X 10^(-7) M. By contrast, procaine effects a greater fractional inhibition of the conductance at high negative potentials.
|Additional Information:||Copyright © 1975 by The Rockefeller University Press. RUP grants the public the non-exclusive right to copy, distribute, or display the Work under a Creative Commons Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/ and http://creativecommons.org/licenses/by-nc-sa/3.0/legalcode. Received for publication 15 November 1974. We thank Mmes. S. Meugon and H. Nuret for expert assistance and P. Ascher, E.A. Barnard, H. Buc, J. B. Cohen, F.A. Dodge, A. Marry, R. Olsen, J.-L. Popot, and M. Weber for fruitful discussions. F. Sigworth built an improved voltage-clamp circuit for use in the instantaneous experiments. The investigations were supported by the U.S. National Institutes of Health (postdoctoral fellowship and grant NS-11756 to H.A.L.) and National Science Foundation (predoctoral Fellowship to R.E.S.), the Centre National de la Recherche Scientifique, the Délégation Générale a la Recherche Scientifique et Technique, the Fondation pour la Recherche Médicale Française, the Collège de France, and the Commissariat à l'Energie Atomique.|
|Usage Policy:||RUP grants the public the non-exclusive right to copy, distribute, or display the Work under a Creative Commons Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/ and http://creativecommons.org/licenses/by-nc-sa/3.0/legalcode.|
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