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The mechanism of beta-bungarotoxin on spontaneous transmitter release at developing neuromuscular synapse.

beta-Bungarotoxin (beta-BuTx), the presynaptic neurotoxin purified from the venom of Bungarus multicinctus, consists of two dissimilar polypeptide subunits. A phospholipase A2 subunit named A chain, and a non-phospholipase A2 subunits named B chain. The A chain and B chain are covalently linked by one disulfide bridge. Although it has been widely accepted that the toxic effect of beta-BuTx is attributed to the disturbance of presynaptic transmitter release, however the inhibition of transmitter release by beta-BuTx is still obscure. Here we investigate the mechanism that mediates facilitation of transmitter release at the neuromuscular junction induced by beta-BuTx, using Xenopus nerve-muscle coculture.
Application of beta-BuTx and isotoxins BM12, BM13 led to a marked increase in the frequency of spontaneous synaptic currents (SSCs) after a short period (12~18 min) of latency. The synaptic potentiation induced by these toxins was abolished when Ca2+ in the medium is substituted by Ba2+ (a potent phospholipase A2 inhibitor). Application of PLP-BM12 and PLP-BM13, which have been chemical-modification to lose their PLA2 activity from BM12 and BM13, failed to potentiate the transmitter release.

Identiferoai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0721103-153108
Date21 July 2003
CreatorsKang, Kai-Hsiang
ContributorsWen-Mei Fu, Long-Sen Chang, Jau-Cheng Liou, Ing-Jun Chen
PublisherNSYSU
Source SetsNSYSU Electronic Thesis and Dissertation Archive
LanguageCholon
Detected LanguageEnglish
Typetext
Formatapplication/pdf
Sourcehttp://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0721103-153108
Rightswithheld, Copyright information available at source archive

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