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. α-Bungarotoxin purified from this venom failed to block transmission at 50μg/ml. A second neurotoxin, which we designate Toxin F, blocked transmission at 1–3μg/ml and also blocked ganglionic depolarizations induced by carbachol. Toxin F was clearly distinguishable from α-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 α-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.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
