Neuromuscular activity of BaTX, a presynaptic basic PLA2 isolated from Bothrops alternatus snake venom

Autor: A.P. Corrado, C. A. Dal Belo, Stephen Hyslop, Luis Alberto Ponce-Soto, J.C. Barros, S. Hernandez, Léa Rodrigues-Simioni, Sergio Marangoni
Rok vydání: 2008
Předmět:
Male
Time Factors
Physiology
Health
Toxicology and Mutagenesis
Diaphragm
Neuromuscular Junction
Presynaptic Terminals
Chick Embryo
Pharmacology
Cholinergic Agonists
Toxicology
medicine.disease_cause
Biochemistry
Synaptic Transmission
Mice
Phospholipase A2
Sequence Analysis
Protein
Crotalid Venoms
medicine
Neurotoxin
Animals
Bothrops
Chromatography
High Pressure Liquid
Neuromuscular Blockade
biology
Dose-Response Relationship
Drug
Chemistry
Toxin
Miniature Postsynaptic Potentials
Temperature
Cell Biology
General Medicine
Electric Stimulation
Blockade
Molecular Weight
Phrenic Nerve
Phospholipases A2
Mechanism of action
Snake venom
Spectrometry
Mass
Matrix-Assisted Laser Desorption-Ionization
biology.protein
Calcium
Electrophoresis
Polyacrylamide Gel
medicine.symptom
Neuromuscular Blocking Agents
Acetylcholine
medicine.drug
Zdroj: Comparative biochemistry and physiology. Toxicologypharmacology : CBP. 150(2)
ISSN: 1532-0456
Popis: We have previously isolated a Lys49 phospholipase A(2) homolog (BaTX) from Bothrops alternatus snake venom using a combination of molecular exclusion chromatography and reverse phase HPLC and shown its ability to cause neuromuscular blockade. In this work, we describe a one-step procedure for the purification of this toxin and provide further details of its neuromuscular activity. The toxin was purified by reverse phase HPLC and its purity and molecular mass were confirmed by SDS-PAGE, MALDI-TOF mass spectrometry, amino acid analysis and N-terminal sequencing. BaTX (0.007-1.4 microM) produced time-dependent, irreversible neuromuscular blockade in isolated mouse phrenic nerve-diaphragm and chick biventer cervicis preparations (time to 50% blockade with 0.35 microM toxin: 58+/-4 and 24+/-1 min, respectively; n=3-8; mean+/-S.E.) without significantly affecting the response to direct muscle stimulation. In chick preparations, contractures to exogenous acetylcholine (55 and 110 microM) or KCl (13.4 mM) were unaltered after complete blockade by all toxin concentrations. These results, which strongly suggested a presynaptic mechanism of action for this toxin, were reinforced by (1) the inability of BaTX to interfere with the carbachol-induced depolarization of the resting membrane, (2) a significant decrease in the frequency and amplitude of miniature end-plate potentials, and (3) a significant reduction (59+/-4%, n=12) in the quantal content of the end-plate potentials after a 60 min incubation with the toxin (1.4 microM). In addition, a decrease in the organ bath temperature from 37 degrees C to 24 degrees C and/or the replacement of calcium with strontium prevented the neuromuscular blockade, indicating a temperature-dependent effect possibly mediated by enzymatic activity.
Databáze: OpenAIRE
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