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Presynaptic effects of d‐tubocurarine on neurotransmitter release at the neuromuscular junction of the frog.
Author(s) -
Matzner H,
Parnas H,
Parnas I
Publication year - 1988
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1988.sp017032
Subject(s) - d tubocurarine , neuromuscular junction , neurotransmitter , facilitation , extracellular , biophysics , chemistry , neurotransmission , neuroscience , biology , receptor , biochemistry , pharmacology
1. Presynaptic effects of d‐tubocurarine on neurotransmitter release were examined at the frog neuromuscular junction, using intracellular and extracellular recording techniques. 2. d‐Tubocurarine in concentrations of 10(‐7)‐10(‐6) M decreased the quantal content (m) measured by the coefficient of variation and failure methods. 3. d‐Tubocurarine produced a shift to the right of the curve relating log quantal content to log [Ca2+]o without changing the slope. 4. The duration of twin‐impulse facilitation was not affected by 5 x 10(‐7) M‐d‐tubocurarine. Early facilitation was higher in d‐tubocurarine. 5. d‐Tubocurarine altered the synaptic delay histogram. The peak of the histogram was shifted to longer delays. Prolongation of the minimal delay was seen in most but not all experiments. 6. These results suggest that d‐tubocurarine inhibits release of neurotransmitter by affecting a stage in the process of release, which occurs after the entry of Ca2+ ions.