Presynaptic action of Bothriopsis bilineata smargadina (forest viper) venom in vitro

Abstract

In this work, we examined the neuromuscular activity of Bothriopsis bilineata smargadina (forest viper) venom in vertebrate isolated nerve-muscle preparations. In chick biventer cervicis preparations the venom caused concentration-dependent (0.1-30 μg/ml) neuromuscular blockade that was not reversed by washing, with 50% blockade occurring in 15-90 min. Muscle contractures to exogenous acetylcholine and KCl were unaffected by venom, but there was a slight increase in creatine kinase release after 120 min (from 80 ± 15 to 206 ± 25U/ml, n=6, p<0.05). In mouse phrenic nerve-diaphragm preparations, the venom (1, 10 and 30 μg/ml) produced marked facilitation (∼120% increase above basal) at the highest concentration followed by neuromuscular blockade; the effects at lower concentrations were considerably less marked. Venom increased the quantal content values after 15 and 30 min followed by significant inhibition at ≥ 90 min. However, venom did not alter the muscle membrane resting potential or the response to exogenous carbachol. In both preparations, incubation at 22 °C instead of 37 °C delayed the onset of blockade, as did inhibition of venom PLA(2) activity. In curarized mouse preparations, the venom produced only muscle facilitation. These results indicate that B. b. smargadina venom causes neuromuscular blockade in vitro by a presynaptic mechanism involving PLA(2).

Ultrastructural aspects of mouse nerve-muscle preparation exposed toBothrops jararacussuandBothrops bilineatusvenoms and their toxins BthTX-I and Bbil-TX: Unknown myotoxic effects

“…Mouse phrenic nerve‐hemidiaphragm preparations were incubated for 120 min either with B. jararacussu venom (100 μg/mL), B. bilineatus venom (30 μg/mL), BthTX‐I (50 μg/mL) or Bbil‐TX (3 μg/mL) in Tyrode solution (composition in mM: NaCl 137, KCl 2.7, CaCl 2 1.8, MgCl 2 0.49, NaH 2 PO 4 0.42, NaHCO 3 11.9 and glucose 11.1; pH 7.5 at 37°C) and constantly aerated by carbogen (95% O 2 −5% CO 2 ), while control samples were exposed to Tyrode solution ( n = 4 per group). The concentrations of venoms and toxins are the same previously shown to induce neuromuscular blockade (Floriano et al, ; Oshima‐Franco et al, ; Rodrigues‐Simioni et al, ).…”

“…Adult specimens can achieve 75–100 cm length; its green colour with black spots helps the camouflage for attacking the prey (Figure B). In vitro studies show that the venom of B. bilineatus causes neuromuscular blockade in avian and mammalian isolated nerve‐muscle preparations, and this effect has been attributed to a presynaptic mechanism of action PLA 2 ‐dependent (Rodrigues‐Simioni et al, ) with no apparent myotoxic effect. Recently, a presynaptic‐active Asp49‐PLA 2 (Bbil‐TX) was purified and characterized from this venom (Carregari et al, ), which appears to be responsible for the neurotoxicity shown by crude venom in vitro (Floriano et al, ).…”

Biochemical Characterization and Pharmacological Properties of New Basic PLA2BrTX-I Isolated fromBothrops roedingeri(Roedinger's Lancehead) Mertens, 1942, Snake Venom

“…The fact that the BrtX-I from Bothrops moojeni did not significantly affect the response to ACh and KCl, except when high doses were used, suggests that the venom presents a primordial presynaptic nature. Such neuromuscular blockade characteristics have been attributed to presynaptic-acting PLA 2 from snake [45, 46] as those of Crotalus durissus terrificus [47], Micrurus species [48, 49], and other Bothrops , Bothrops insularis [50], Bothrops pauloensis [47, 51], and Bothriopsis bilineata smargadina [52], which did not show any detectable effect on the nicotinic receptor and, in some cases, showed only a mild muscle alteration.…”

Suramin affects metalloproteinase‐9 activity and increases beta‐dystroglycan levels in the diaphragm of the dystrophin‐deficient mdx MOUSE

“…For diaphragm (DIA) functional analysis, the left hemidiaphragm was mounted, and muscle function assessed as previously described 19–21. For all groups studied, the preparation was suspended under a constant tension of 5 g in an organ bath (5 ml) containing aerated (95% O 2 ‐5% CO 2 ) Tyrode solution (pH 7.4, 37°C) with the following composition: 137 mM NaCl, 2.7 mM KCl, 1.8 mM CaCl 2 , 0.49 mM MgCl 2 , 0.42 mM NaH 2 PO 4 , 11.9 mM NaHCO 3 , and 11.1 mM glucose.…”