Abstract |
Blockade of neuromuscular transmission was produced in the lower hind limb of the rat by local injection of either crystalline type A botulinum toxin or purified type B botulinum neurotoxin. At 1, 3, 5 and 7 days after injection, the extensor digitorum longus nerve-muscle preparation was excised and analyzed in vitro for alterations in spontaneous and nerve stimulus-evoked quantal transmitter release. Muscles receiving type A toxin were paralyzed up to and including 7 days after injection. Muscles treated with type B toxin, although completely paralyzed at 1 and 3 days, twitched in response to nerve stimulation at 5 and 7 days after injection. Both toxins induced a marked decrease in the frequency of miniature endplate potentials but type A did so to a greater extent. The remaining population of miniature endplate potentials contained a greater frequency of potentials with small or large amplitudes and prolonged rise times compared to normal muscle. These changes were more pronounced with type A toxin than with type B toxin. In the presence of alpha-dinitrophenol (1 mM), high frequency, fast-rising miniature endplate potentials of uniform size reappeared. High K+ (20 mM) was less effective in this respect. At 3 days after toxin injection nerve impulse evoked transmitter release was reduced more for type A treated muscles than for type B. However, 3,4-diaminopyridine, an agent which increases nerve-evoked transmitter release by increasing Ca2+ influx, was more effective in reversing the paralysis in type A than in type B-treated muscles.(ABSTRACT TRUNCATED AT 250 WORDS)
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Authors | L C Sellin, S Thesleff, B R Dasgupta |
Journal | Acta physiologica Scandinavica
(Acta Physiol Scand)
Vol. 119
Issue 2
Pg. 127-33
( 1983)
ISSN: 0001-6772 [Print] England |
PMID | 6140815
(Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S., Research Support, U.S. Gov't, P.H.S.)
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Chemical References |
- Aminopyridines
- Dinitrophenols
- Neurotransmitter Agents
- 4-Aminopyridine
- Botulinum Toxins
- Amifampridine
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Topics |
- 4-Aminopyridine
(analogs & derivatives)
- Amifampridine
- Aminopyridines
(pharmacology)
- Animals
- Botulinum Toxins
(pharmacology)
- Dinitrophenols
(pharmacology)
- Electric Stimulation
- Evoked Potentials
(drug effects)
- Male
- Motor Endplate
(physiology)
- Neuromuscular Junction
(metabolism)
- Neurotransmitter Agents
(metabolism)
- Rats
- Rats, Inbred Strains
- Synaptic Transmission
(drug effects)
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