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
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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.
Carbajal-Saucedo A, Floriano RS, Belo CAD, Olvera-Rodríguez A, Alagón A, Rodrigues-Simioni L. Neuromuscular Activity of Micrurus laticollaris (Squamata: Elapidae) Venom in Vitro. Toxins. 2014; 6(1):359-370.
Carbajal-Saucedo, Alejandro; Floriano, Rafael S.; Belo, Cháriston A.D.; Olvera-Rodríguez, Alejandro; Alagón, Alejandro; Rodrigues-Simioni, Léa. 2014. "Neuromuscular Activity of Micrurus laticollaris (Squamata: Elapidae) Venom in Vitro." Toxins 6, no. 1: 359-370.