The effect of (+)‐tubocurarine on neuromuscular transmission during repetitive stimulation in the rat, mouse, and frog.

K. L. Magleby, B. S. Pallotta, D. A. Terrar

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Abstract

The effect of tubocurarine on amplitudes of end-plate currents in response to trains of repetitive stimulation (50-150/sec) was investigated in voltage-clamped muscle fibres of the rat, mouse and frog. In rat and mouse muscle, the presence of tubocurarine led to a more rapid decline (rundown) in the amplitudes of successive end-plate currents during trains of impulses. In frog, tubocurarine caused an increase in apparent facilitation of end-plate current amplitudes during the first few impulses of repetitive stimulation; this increase was followed by a more rapid rundown of end-plate current amplitude. These effects of tubocurarine appear not to be an artifact resulting from inadequate control of membrane potential in voltage-clamped fibres. The more rapid rundown during trains of end-plate currents in the presence of tubocurarine showed little variation with membrane potential indicating that voltage-sensitive channel blockade by tubocurarine was not a major factor contributing to the rundown. The effect of tubocurarine on the apparent facilitation and rundown of end-plate current amplitudes was typically decreased by reducing the frequency of stimulation. These results suggest that tubocurarine effects transmitter release at neuromuscular junctions during repetitive stimulation.

Original languageEnglish (US)
Pages (from-to)97-113
Number of pages17
JournalThe Journal of Physiology
Volume312
Issue number1
DOIs
StatePublished - Mar 1 1981

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ASJC Scopus subject areas

  • Physiology

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