Please use this identifier to cite or link to this item:
|Title:||Neuromuscular effects of candoxin, a novel toxin from the venom of the Malayan krait (Bungarus candidus)||Authors:||Nirthanan, S.
Nicotinic acetylcholine receptors
|Issue Date:||Jun-2003||Citation:||Nirthanan, S., Charpantier, E., Gopalakrishnakone, P., Gwee, M.C.E., Khoo, H.E., Cheah, L.S., Kini, R.M., Bertrand, D. (2003-06). Neuromuscular effects of candoxin, a novel toxin from the venom of the Malayan krait (Bungarus candidus). British Journal of Pharmacology 139 (4) : 832-844. ScholarBank@NUS Repository.||Abstract:||1. Candoxin (MW 7334.6), a novel toxin isolated from the venom of the Malayan krait Bungarus candidus, belongs to the poorly characterized subfamily of nonconventional three-finger toxins present in Elapid venoms. The current study details the pharmacological effects of candoxin at the neuromuscular junction. 2. Candoxin produces a novel pattern of neuromuscular blockade in isolated nerve-muscle preparations and the tibialis anterior muscle of anaesthetized rats. In contrast to the virtually irreversible postsynaptic neuromuscular blockade produced by curaremimetic α-neurotoxins, the neuromuscular blockade produced by candoxin was rapidly and completely reversed by washing or by the addition of the anticholinesterase neostigmine. 3. Candoxin also produced significant train-of-four fade during the onset of and recovery from neuromuscular blockade, both, in vitro and in vivo. The fade phenomenon has been attributed to a blockade of putative presynaptic nicotinic acetylcholine receptors (nAChRs) that mediate a positive feedback mechanism and maintain adequate transmitter release during rapid repetitive stimulation. In this respect, candoxin closely resembles the neuromuscular blocking effects of d-tubocurarine, and differs markedly from curaremimetic α-neurotoxins that produce little or no fade. 4. Electrophysiological experiments confirmed that candoxin produced a readily reversible blockade (IC 50∼10 nM) of oocyte-expressed muscle (αβγδ) nAChRs. Like α-conotoxin MI, well known for its preferential binding to the α/δ interface of the muscle (αβγδ) nAChR, candoxin also demonstrated a biphasic concentration - response inhibition curve with a high- (IC 50∼2.2 nM) and a low-(IC 50∼98 nM) affinity component, suggesting that it may exhibit differential affinities for the two binding sites on the muscle (αβγδ) receptor. In contrast, curaremimetic α-neurotoxins have been reported to antagonize both binding sites with equal affinity.||Source Title:||British Journal of Pharmacology||URI:||http://scholarbank.nus.edu.sg/handle/10635/101194||ISSN:||00071188|
|Appears in Collections:||Staff Publications|
Show full item record
Files in This Item:
There are no files associated with this item.
checked on Feb 27, 2018
WEB OF SCIENCETM
checked on Oct 1, 2021
checked on Oct 14, 2021
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.