and plant extracts against the local effects of and snake venoms.

produces similar local effects to snakebite, which can induce misidentification and bothropic antivenom administration. Antivenom therapy is effective, but has its limitations regarding local damage. Since plants are used in folk medicine to treat snakebite victims, we evaluated the protective properties of and extracts against and venoms.

Inhibition of Kv2.1 Potassium Channels by MiDCA1, A Pre-Synaptically Active PLA-Type Toxin from Coral Snake Venom.

MiDCA1, a phospholipase A (PLA) neurotoxin isolated from coral snake venom, inhibited a major component of voltage-activated potassium (Kv) currents (41 ± 3% inhibition with 1 μM toxin) in mouse cultured dorsal root ganglion (DRG) neurons. In addition, the selective Kv2.1 channel blocker guangxitoxin (GxTx-1E) and MiDCA1 competitively inhibited the outward potassium current in DRG neurons.

Presynaptic Activity of an Isolated Fraction from Rhinella schneideri Poison.

Rhinella schneideri is a toad found in many regions of the South America. The poison of the glands has cardiotoxic effect in animals and neuromuscular effects in mice and avian preparation. The purpose of this work was to identify the toxin responsible for the neuromuscular effect in avian and mice neuromuscular preparation.

A survey on some biochemical and pharmacological activities of venom from two Colombian colubrid snakes, Erythrolamprus bizona (Double-banded coral snake mimic) and Pseudoboa neuwiedii (Neuwied's false boa).

Colombian colubrid snake venoms have been poorly studied. They represent a great resource of biological, ecological, toxinological and pharmacological research. We assessed some enzymatic properties and neuromuscular effects of Erythrolamprus bizona and Pseudoboa neuwiedii venoms from Colombia.

Influence of phospholipasic inhibition on neuromuscular activity of Bothrops fonsecai snake venom.

Bothrops fonsecai (B. fonsecai), a pitviper endemic to southeastern Brazil, has a venom mainly composed by snake venom phospholipases (PLA) and metalloproteases, compounds that could interfere with neuromuscular junction in vitro. In this work, we investigated the role of PLA in the myotoxicity and neuromuscular blockade caused by B.

Ultrastructural aspects of mouse nerve-muscle preparation exposed to Bothrops jararacussu and Bothrops bilineatus venoms and their toxins BthTX-I and Bbil-TX: Unknown myotoxic effects.

Bites by Bothrops snakes normally induce local pain, haemorrhage, oedema and myonecrosis. Mammalian isolated nerve-muscle preparations exposed to Bothrops venoms and their phospholipase A toxins (PLA ) can exhibit a neurotoxic pattern as increase in frequency of miniature end-plate potentials (MEPPs) as well as in amplitude of end-plate potentials (EPPs); neuromuscular facilitation followed by complete and irreversible blockade without morphological evidence for muscle damage. In this work, we analysed the ultrastructural damage induced by Bothrops jararacussu and Bothrops bilineatus venoms and their PLA toxins (BthTX-I and Bbil-TX) in mouse isolated nerve-phrenic diaphragm preparations (PND).

Bothrops fonsecai snake venom activities and cross-reactivity with commercial bothropic venom.

In this work, we examined some biochemical and biological activities of Bothrops fonsecai venom, a pitviper endemic to southeastern Brazil, and assessed their neutralization by commercial bothropic antivenom (CAv). Cross-reactivity of venom with CAv was also assessed by immunoblotting and size-exclusion high performance chromatography (SE-HPLC). Bothrops fonsecai venom had PLA, proteolytic and esterase activities that were neutralized to varying extents by venom:antivenom ratios of 5:1 and 5:2 (PLA and esterase activities) or not significantly by either venom:antivenom ratio (proteolytic activity).

Presynaptic Proteins as Markers of the Neurotoxic Activity of BmjeTX-I and BmjeTX-II Toxins from Bothrops marajoensis (Marajó Lancehead) Snake Venom.

Neuromuscular preparations exposed to B. marajoensis venom show increases in the frequency of miniature end-plate potentials and twitch tension facilitation followed by presynaptic neuromuscular paralysis, without evidences of muscle damage. Considering that presynaptic toxins interfere into the machinery involved in neurotransmitter release (synaptophysin, synaptobrevin, and SNAP25 proteins), the main objective of this communication is to analyze, by immunofluorescence and western blotting, the expression of the synaptic proteins, synaptophysin, synaptobrevin, and SNAP25 and by myography, light, and transmission electron microscopy the pathology of motor nerve terminals and skeletal muscle fibres of chick biventer cervicis preparations (CBC) exposed in vitro to BmjeTX-I and BmjeTX-II toxins from B.

Functional and structural studies of a Phospholipase A-like protein complexed to zinc ions: Insights on its myotoxicity and inhibition mechanism.

Background: One of the main challenges in snakebite envenomation treatment is the development of stable, versatile and efficient anti-venom therapies. Local myotoxicity in accidents involving snakes from the Bothrops genus is still a consequence of serum therapy inefficient neutralization that may lead to permanent sequelae in their victims. One of the classes of toxins that participate in muscle necrosis is the PLA-like proteins.

Biological activities of Leptodeira annulata (banded cat-eyed snake) venom on vertebrate neuromuscular preparations.

The physiological properties of colubrid snake venoms are largely unknown and less frequently investigated. In this study, we assessed the enzymatic properties and biological activities of Leptodeira annulata (banded cat-eyed snake) venom, an opistoglyphous snake from Colombia. The proteolytic, phospholipase A2 and amidolytic activities are assessed using colorimetric assays and the biological activities were analyzed in avian and mammalian neuromuscular preparations.

Neutralization of the neuromuscular inhibition of venom and taipoxin from the taipan (Oxyuranus scutellatus) by F(ab')2 and whole IgG antivenoms.

The neuromuscular junction activity of Oxyuranus scutellatus venom and its presynaptic neurotoxin, taipoxin, and their neutralization by two antivenoms were examined in mouse phrenic nerve-diaphragm preparations. The action of taipoxin was also studied at 21°C. The efficacy of the antivenoms was also assessed in an in vivo mouse model.

Bp-13 PLA2: Purification and Neuromuscular Activity of a New Asp49 Toxin Isolated from Bothrops pauloensis Snake Venom.

A new PLA2 (Bp-13) was purified from Bothrops pauloensis snake venom after a single chromatographic step of RP-HPLC on μ-Bondapak C-18. Amino acid analysis showed a high content of hydrophobic and basic amino acids and 14 half-cysteine residues. The N-terminal sequence showed a high degree of homology with basic Asp49 PLA2 myotoxins from other Bothrops venoms.

The neuromuscular activity of Bothriopsis bilineata smaragdina (forest viper) venom and its toxin Bbil-TX (Asp49 phospholipase A2) on isolated mouse nerve-muscle preparations.

The presynaptic action of Bothriopsis bilineata smaragdina (forest viper) venom and Bbil-TX, an Asp49 PLA2 from this venom, was examined in detail in mouse phrenic nerve-muscle (PND) preparations in vitro and in a neuroblastoma cell line (SK-N-SH) in order to gain a better insight into the mechanism of action of the venom and associated Asp49 PLA2. In low Ca(2+) solution, venom (3μg/ml) caused a quadriphasic response in PND twitch height whilst at 10μg/ml the venom additionally induced an abrupt and marked initial contracture followed by neuromuscular facilitation, rhythmic oscillations of nerve-evoked twitches, alterations in baseline and progressive blockade. The venom slowed the relaxation phase of muscle twitches.

Neuromuscular activity of Bothrops fonsecai snake venom in vertebrate preparations.

The neuromuscular activity of venom from Bothrops fonsecai, a lancehead endemic to southeastern Brazil, was investigated. Chick biventer cervicis (CBC) and mouse phrenic nerve-diaphragm (PND) preparations were used for myographic recordings and mouse diaphragm muscle was used for membrane resting potential (RP) and miniature end-plate potential (MEPP) recordings. Creatine kinase release and muscle damage were also assessed.

Presynaptic neuromuscular action of a methanolic extract from the venom of Rhinella schneideri toad.

Background: Rhinella schneideri, previously known as Bufo paracnemis, is a common toad in many regions of Brazil. Its venom exerts important cardiovascular effects on humans and other animals. Although this toad venom has been the subject of intense investigations, little is known about its neuromuscular activity.

In vitro antiophidian mechanisms of Hypericum brasiliense choisy standardized extract: quercetin-dependent neuroprotection.

The neuroprotection induced by Hypericum brasiliense Choisy extract (HBE) and its main active polyphenol compound quercetin, against Crotalus durissus terrificus (Cdt) venom and crotoxin and crotamine, was enquired at both central and peripheral mammal nervous system. Cdt venom (10 μg/mL) or crotoxin (1 μg/mL) incubated at mouse phrenic nerve-diaphragm preparation (PND) induced an irreversible and complete neuromuscular blockade, respectively. Crotamine (1 μg/mL) only induced an increase of muscle strength at PND preparations.

Neuromuscular activity of Micrurus laticollaris (Squamata: Elapidae) venom in vitro.

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.

VdTX-1, a reversible nicotinic receptor antagonist isolated from venom of the spider Vitalius dubius (Theraphosidae).

Theraphosid spider venoms can block neurotransmission in vertebrate nerve-muscle preparations in vitro, but few of the components involved have been characterized. In this work, we describe the neuromuscular activity of venom from the Brazilian theraphosid Vitalius dubius and report the purification and pharmacological characterization of VdTX-1, a 728 Da toxin that blocks nicotinic receptors. Neuromuscular activity was assayed in chick biventer cervicis preparations and muscle responses to exogenous ACh and KCl were determined before and after incubation with venom or toxin.

Pharmacological study of a new Asp49 phospholipase A(2) (Bbil-TX) isolated from Bothriopsis bilineata smargadina (forest viper) venom in vertebrate neuromuscular preparations.

The neuromuscular activity of Bbil-TX, a PLA2 with catalytic activity isolated from Bothriopsis bilineata smargadina venom, was examined in chick biventer cervicis (BC) and mouse phrenic nerve-diaphragm (PND) preparations. In BC preparations, Bbil-TX (0.5-10 μg/ml) caused time- and concentration-dependent blockade that was not reversed by washing; the times for 50% blockade were 87 ± 7, 41 ± 7 and 19 ± 2 min (mean ± SEM; n = 4-6) for 1, 5 and 10 μg/ml, respectively.

Biochemical, pharmacological, and structural characterization of new basic PLA2 Bbil-TX from Bothriopsis bilineata snake venom.

Bbil-TX, a PLA2, was purified from Bothriopsis bilineata snake venom after only one chromatographic step using RP-HPLC on μ-Bondapak C-18 column. A molecular mass of 14243.8 Da was confirmed by Q-Tof Ultima API ESI/MS (TOF MS mode) mass spectrometry.

Beneficial effect of crotamine in the treatment of myasthenic rats.

Introduction: Crotamine is a basic, low-molecular-weight peptide that, at low concentrations, improves neurotransmission in isolated neuromuscular preparations by modulating sodium channels. In this study, we compared the effects of crotamine and neostigmine on neuromuscular transmission in myasthenic rats.

Methods: We used a conventional electromyographic technique in in-situ neuromuscular preparations and a 4-week treadmill program.

Suramin affects metalloproteinase-9 activity and increases β-dystroglycan levels in the diaphragm of the dystrophin-deficient mdx mouse.

Introduction: In Duchenne muscular dystrophy and in the mdx mouse, muscle fiber degeneration and subsequent fibrosis lead to cardiorespiratory failure. Previously, we demonstrated that the anti-fibrotic agent suramin was effective in decreasing fibrosis in mdx muscles. In this study, we were interested to see whether suramin could affect metalloproteinases (MMP) and improve the functional activity of the mdx diaphragm muscle.

Guanidine affects differentially the twitch response of diaphragm, extensor digitorum longus and soleus nerve-muscle preparations of mice.

Guanidine has been used with some success to treat myasthenia gravis and myasthenic syndrome because it increases acetylcholine release at nerve terminals through K⁺, Na⁺ and Ca²⁺ channels-involving mechanisms. Currently, guanidine derivatives have been proposed for treatment of several diseases. Studies aimed at providing new insights to the drug are relevant.

Protection by Mikania laevigata (guaco) extract against the toxicity of Philodryas olfersii snake venom.

Philodryas olfersii is responsible for most colubrid snakebites in Brazil. In this work, we examined the ability of an ethanolic extract from Mikania laevigata (guaco) leaves to protect against the in vitro neuromuscular activity of P. olfersii venom in mouse phrenic nerve-diaphragm (PND) and chick biventer cervicis (BC) preparations.