Document Detail

A study of synchronization of quantal transmitter release from mammalian motor endings by the use of botulinal toxins type A and D.
MedLine Citation:
PMID:  2575665     Owner:  NLM     Status:  MEDLINE    
1. The effects of botulinum toxin (BoTx) types A and D on spontaneous and evoked phasic transmitter release were studied in the isolated extensor digitorum longus muscle of the rat or the levator auris longus muscle of mice. 2. The toxins were injected subcutaneously into the hindleg of adult rats or the dorsal aspect of the neck of mice. At various times after the injection the muscles were removed from the anaesthetized animal and neuromuscular transmission examined in vitro by conventional intracellular techniques. 3. Both toxins reduced spontaneous transmitter release recorded as the frequency of miniature end-plate potentials but BoTx type D was less effective in that respect than the type A toxin. 4. With both toxins the block of evoked phasic transmitter release, recorded as end-plate potentials, was almost complete. As previously reviewed by Simpson (1986) the block produced by BoTx type A was partially reversed by procedures which elevate the intraterminal level of calcium ions. However, in BoTx type D-paralysed muscles such procedures failed to restore phasic transmitter release but caused a period of high-frequency asynchronous transmitter release following each nerve impulse. 5. To investigate if the lack of synchronization of evoked transmitter release observed in BoTx type D-paralysed muscles was due to alterations in presynaptic currents we examined, by perineural recordings, the Na+, fast K+, slow K+, K+-Ca2+-dependent and the Ca2+ currents in BoTx type D-paralysed muscles. These presynaptic currents were not altered as compared to unpoisoned controls. 6. We suggest that there exists a presynaptic process, which in addition to Ca2+ influx participates in transmitter synchronization and which is a main target for BoTx type D action.
J Molgó; L S Siegel; N Tabti; S Thesleff
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of physiology     Volume:  411     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  1989 Apr 
Date Detail:
Created Date:  1990-02-26     Completed Date:  1990-02-26     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  195-205     Citation Subset:  IM    
Laboratoire de Neurobiologie Cellulaire et Moléculaire, CNRS, Gif sur Yvette, France.
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MeSH Terms
4-Aminopyridine / analogs & derivatives,  pharmacology
Action Potentials / drug effects
Botulinum Toxins / pharmacology*
Motor Endplate / drug effects*
Neuromuscular Junction / drug effects*,  physiology
Neurotransmitter Agents / metabolism
Rats, Inbred Strains
Synaptic Transmission / drug effects
Tetraethylammonium Compounds / pharmacology
Reg. No./Substance:
0/Botulinum Toxins; 0/Neurotransmitter Agents; 0/Tetraethylammonium Compounds; 504-24-5/4-Aminopyridine; 54-96-6/3,4-diaminopyridine; 66-40-0/Tetraethylammonium

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