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

Toxins

Alejandro Carbajal-Saucedo²  Rafael Stuani Floriano³  Cháriston André Dal Belo¹  Alejandro Olvera-Rodríguez²  Alejandro Alagón² 

[1] Interdisciplinar Center for Biotechnology (CIPBiotec), Campus São Gabriel, Federal University of Pampa (UNIPAMPA), Antônio Trilha Av., 1847, São Gabriel, RS 97300-000, Brazil; E-Mail:;Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, Cuernavaca, Morelos, CP. 62210, Mexico; E-Mails:;Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Tessália Vieira Camargo St., 126, Campinas, SP 13083-887, Brazil; E-Mail:

关键词: snake venom;    Micrurus laticollaris;    presynaptic action;    postsynaptic action;    neuromuscular preparations;   

DOI  :  10.3390/toxins6010359

来源: mdpi

【 摘 要 】

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.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.