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Journal Article

Decamethonium both opens and blocks endplate channels

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Sakmann,  Bert
Department of Cell Physiology, Max Planck Institute for Medical Research, Max Planck Society;

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Citation

Adams, P. R., & Sakmann, B. (1978). Decamethonium both opens and blocks endplate channels. Proceedings of the National Academy of Sciences of the United States of America, 75(6), 2994-2998. doi:10.1073/pnas.75.6.2994.


Cite as: https://hdl.handle.net/21.11116/0000-0001-2805-D
Abstract
Miniature endplate currents, endplate current fluctuations ("membrane noise"), and voltage-jump current relaxations were studied in voltage-clamped frog muscle fibers during decamethonium action. All three types of experiments revealed two kinetic processes controlling the opening of endplate channels, one that reflects agonist action and another that reflects local anesthetic-like blocking activity. The kinetic constants for these two steps were evaluated from measurements of the fast and slow time constants as a function of decamethonium concentration. At -130 mV membrane potential and 13 degrees, the mean open time of decamethonium-activated channels is 2.8 msec. The forward and backward rate constants for channel blocking are 1.7 X 10(7) M-1 sec-1 and 10(3) sec-1. The voltage dependencies of the channel lifetime and of the blocking equilibrium are similar to those seen with pure agonists and local anesthetics, respectively.