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Protease inhibitor homologues from mamba venoms : facilitation of acetylcholine release and interactions with prejunctional blocking toxins

Harvey, A L and Karlsson, E (1982) Protease inhibitor homologues from mamba venoms : facilitation of acetylcholine release and interactions with prejunctional blocking toxins. British Journal of Pharmacology, 77 (1). pp. 153-161. ISSN 0007-1188

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Abstract

1 Five polypeptides, which were isolated from elapid snake venoms and which are structurally related to protease inhibitors, were tested for action on isolated biventer cervicis nerve-muscle preparations of the chick. 2 Dendrotoxin from the Eastern green mamba (Dendroaspis angusticeps) and toxins K and I from the black mamba (Dendroaspis polylepis polylepis) increased to indirect stimulation without affecting responses to exogenous acetylcholine, carbachol of KCl. 3 The two other protease inhibitor homologues, HHV-II from Ringhals cobra (Hemachatus haemachatus) and NNV-II from Cape cobra (Naja nivea) did not increase responses to nerve stimulation. Trypsin inhibitor from bovine pancreas also had no facilitatory effects on neuromuscular transmission. 4 The facilitatory toxins from mamba venoms interacted with the prejunctional blocking toxins, beta-bungarotoxin, crotoxin and notexin, but not with taipoxin. The blocking effects of beta-bungarotoxin were reduced by pretreatment with the mamba toxins, whereas the blocking actions of crotoxin and notexin were enhanced. 5 The results indicate that protease inhibitor homologues from mamba venoms form a new class of neurotoxin, which acts to increase the release of acetylcholine in response to motor nerve stimulation. 6 From the interaction studies it is concluded that the facilitatory toxins bind to motor nerve terminals at sites related to those occupied by the prejunctional blocking toxins. However, differences in interactions with individual toxins suggest that there must be several related binding sites on the nerve terminals.

Item type: Article
ID code: 31701
Keywords: acetylcholine, animals, carbachol, chickens, cobra venoms, muscle contraction, neurotoxins, potassium chloride, protease inhibitors, snake venoms, biological toxins, Pharmacy and materia medica, Pharmacology
Subjects: Medicine > Pharmacy and materia medica
Department: Faculty of Science > Strathclyde Institute of Pharmacy and Biomedical Sciences
Related URLs:
    Depositing user: Pure Administrator
    Date Deposited: 13 Jul 2011 09:57
    Last modified: 05 Sep 2014 09:34
    URI: http://strathprints.strath.ac.uk/id/eprint/31701

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