Abstract |
Bungarus multicinctus venom was fractionated by ion exchange chromatography and the various fractions were assayed for their ability to block synaptic transmission through the chick ciliary ganglion. alpha-Bungarotoxin purified from this venom failed to block transmission at 50 micrograms/ml. A second neurotoxin, which we designate Toxin F, blocked transmission at 1-3 micrograms/ml and also blocked ganglionic depolarizations induced by carbachol. Toxin F was clearly distinguishable from alpha-bungarotoxin on the basis of molecular weight (estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis) and isoelectric point. Binding assays revealed that 125I-labeled toxin F bound to two sites in the ciliary ganglion: one site that was shared by alpha-bungarotoxin and toxin F and another site that was recognized solely by toxin F. Carbachol and d-tubocurarine displaced only that [125I]toxin F bound to the shared site and had no effect on [125I]toxin F bound to the site recognized by toxin F alone. The results suggest that toxin F blocks synaptic transmission in the chick ciliary ganglion by a postsynaptic mechanism. Further study is required to determine whether this effect of toxin F is mediated through a direct interaction with ganglionic nicotinic receptors.
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Authors | R H Loring, V A Chiappinelli, R E Zigmond, J B Cohen |
Journal | Neuroscience
(Neuroscience)
Vol. 11
Issue 4
Pg. 989-99
(Apr 1984)
ISSN: 0306-4522 [Print] United States |
PMID | 6330611
(Publication Type: Comparative Study, Journal Article, Research Support, U.S. Gov't, P.H.S.)
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Chemical References |
- Bungarotoxins
- Neurotoxins
- Receptors, Nicotinic
- Reptilian Proteins
- Snake Venoms
- snake venom neurotoxin F
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Topics |
- Animals
- Binding Sites
- Bungarotoxins
(isolation & purification, metabolism, pharmacology)
- Chickens
- Ciliary Body
(innervation)
- Depression, Chemical
- Electrophoresis, Polyacrylamide Gel
- Ganglia, Parasympathetic
(drug effects)
- Neurotoxins
(isolation & purification, pharmacology)
- Receptors, Nicotinic
(drug effects)
- Reptilian Proteins
- Snake Venoms
(isolation & purification, pharmacology)
- Synaptic Transmission
(drug effects)
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