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Presynaptic Effects of Potassium Ion on the Mammalian Neuromuscular Junction

Abstract

THE depolarization of motor nerve terminals by the application of a cathodic current increases the frequency of spontaneous miniature potentials (m.e.p.p.s), but under these conditions the number of such quantal units of transmitter released by a nerve impulse is decreased in proportion to the intensity of the presynaptic depolarization1–3. Although the depolarization of the nerve terminal by elevating the potassium concentration also causes an increase in the frequency of m.e.p.p.s, the potentiation in this case continues to develop even after depolarization has reached a maximum3,4. Although equivalent depolarization can be achieved both electrically and chemically, the effects of these stimuli are not entirely parallel, as the quantum content of the end-plate potential is decreased in the first case but is potentiated in the second1,2,5.

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PARSONS, R., HOFMANN, W. & FEIGEN, G. Presynaptic Effects of Potassium Ion on the Mammalian Neuromuscular Junction. Nature 208, 590–591 (1965). https://doi.org/10.1038/208590a0

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