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Toxins 2014, 6(1), 359-370; doi:10.3390/toxins6010359
Article

Neuromuscular Activity of Micrurus laticollaris (Squamata: Elapidae) Venom in Vitro

1
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2
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3
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1
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1
 and
2,*
1 Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, Cuernavaca, Morelos, CP. 62210, Mexico 2 Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Tessália Vieira Camargo St., 126, Campinas, SP 13083-887, Brazil 3 Interdisciplinar Center for Biotechnology (CIPBiotec), Campus São Gabriel, Federal University of Pampa (UNIPAMPA), Antônio Trilha Av., 1847, São Gabriel, RS 97300-000, Brazil
* Author to whom correspondence should be addressed.
Received: 25 October 2013 / Revised: 20 December 2013 / Accepted: 30 December 2013 / Published: 17 January 2014
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Abstract

In this work, we have examined the neuromuscular activity of Micrurus laticollaris (Mexican coral snake) venom (MLV) in vertebrate isolated nerve-muscle preparations. In chick biventer cervicis preparations, the MLV induced an irreversible concentration- and time-dependent (1–30 µg/mL) neuromuscular blockade, with 50% blockade occurring between 8 and 30 min. Muscle contractures evoked by exogenous acetylcholine were completely abolished by MLV, whereas those of KCl were also significantly altered (86% ± 11%, 53% ± 11%, 89% ± 5% and 89% ± 7% for one, three, 10 and 30 µg of venom/mL, respectively; n = 4; p < 0.05). In mouse phrenic nerve-diaphragm preparations, MLV (1–10 µg/mL) promoted a slight increase in the amplitude of twitch-tension (3 µg/mL), followed by neuromuscular blockade (n = 4); the highest concentration caused complete inhibition of the twitches (time for 50% blockade = 26 ± 3 min), without exhibiting a previous neuromuscular facilitation. The venom (3 µg/mL) induced a biphasic modulation in the frequency of miniature end-plate potentials (MEPPs)/min, causing a significant increase after 15 min, followed by a decrease after 60 min (from 17 ± 1.4 (basal) to 28 ± 2.5 (t15) and 12 ± 2 (t60)). The membrane resting potential of mouse diaphragm preparations pre-exposed or not to d-tubocurarine (5 µg/mL) was also significantly less negative with MLV (10 µg/mL). Together, these results indicate that M. laticollaris venom induces neuromuscular blockade by a combination of pre- and post-synaptic activities.
Keywords: snake venom; Micrurus laticollaris; presynaptic action; postsynaptic action; neuromuscular preparations snake venom; Micrurus laticollaris; presynaptic action; postsynaptic action; neuromuscular preparations
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).
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Carbajal-Saucedo, A.; Floriano, R.S.; Belo, C.A.D.; Olvera-Rodríguez, A.; Alagón, A.; Rodrigues-Simioni, L. Neuromuscular Activity of Micrurus laticollaris (Squamata: Elapidae) Venom in Vitro. Toxins 2014, 6, 359-370.

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