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dc.contributor.authorNirthanan, Sen_US
dc.contributor.authorCharpantier, Een_US
dc.contributor.authorGopalakrishnakone, Pen_US
dc.contributor.authorE Gwee, Men_US
dc.contributor.authorKhoo, Hen_US
dc.contributor.authorCheah, Len_US
dc.contributor.authorKini, Ren_US
dc.contributor.authorBertrand, Den_US
dc.description.abstract1 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 a-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 a-neurotoxins that produce little or no fade. 4 Electrophysiological experiments confirmed that candoxin produced a readily reversible blockade (IC50~10 nM) of oocyte-expressed muscle (a߿d) nAChRs. Like a-conotoxin MI, well known for its preferential binding to the a/d interface of the muscle (a߿d) nAChR, candoxin also demonstrated a biphasic concentration - response inhibition curve with a high- (IC50~2.2 nM) and a low-(IC50~98 nM) affinity component, suggesting that it may exhibit differential affinities for the two binding sites on the muscle (a߿d) receptor. In contrast, curaremimetic a-neurotoxins have been reported to antagonize both binding sites with equal affinity.en_US
dc.publisherNature Publishing Groupen_US
dc.publisher.placeUnited Statesen_US
dc.relation.ispartofjournalBritish Journal of Pharmacologyen_US
dc.subject.fieldofresearchBasic Pharmacologyen_US
dc.titleNeuromuscular effects of candoxin, a novel toxin from the venom of the Malayan krait (Bungarus candidus).en_US
dc.typeJournal articleen_US
dc.type.descriptionC1 - Peer Reviewed (HERDC)en_US
dc.type.codeC - Journal Articlesen_US
gro.hasfulltextNo Full Text

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