Hemodynamic responses to Lachesis muta (South American bushmaster) snake venom in anesthetized rats.

Abstract

In this work, we examined the hemodynamic responses to Lachesis muta (South American bushmaster) venom in anesthetized male Wistar rats. Venom (1.5 mg/kg, i.v.) caused immediate hypotension that was followed by a gradual return towards baseline over 60 min; there were no significant changes in heart rate, ECG parameters and respiratory rate. A higher dose (3 mg/kg, i.v.) caused sustained hypotension, variable bradycardia, respiratory depression and fluctuations in ECG; death occurred within 10-60 min. Venom injected intramuscularly (15 mg/kg) produced a smaller decrease in blood pressure that was more persistent than with 1.5 mg/kg (i.v.). Pre-treatment with atenolol (selective β1-adrenergic receptor antagonist) potentiated the response to venom (1.5 mg/kg, i.v.) and resulted in a hemodynamic profile similar to that seen with 3 mg/kg (i.v.). Macroscopically, systemic hemorrhage was seen only in the ileum, whereas histological analysis revealed extensive pulmonary hemorrhage; the heart, liver and kidney were generally unaffected. Intravascular pulmonary thrombosis occurred with venom given i.v. and i.m., but was less marked with the latter route. In rat isolated perfused hearts, venom caused a persistent decrease in left ventricular developed pressure but no change in heart rate, coronary flow or ECG; there was tissue necrosis and release of CK-MB that were abolished by pre-treating venom with the PLA2 inhibitor p-bromophenacyl bromide. These results show that in rats L. muta venom causes hypotension, bradycardia and respiratory depression, depending on the dose and route of administration. The hemodynamic responses apparently do not involve direct cardiotoxicity and are modulated by the adrenergic system.

• Authors: Lourdes Dias, Mariana A P Rodrigues, André L Rennó, Alessandra Stroka, Bruna R Inoue, Patrícia C Panunto, Anibal R Melgarejo, Stephen Hyslop
• Journal: Toxicon : official journal of the International Society on Toxinology (Toxicon) Vol. 123 Pg. 1-14 (Dec 01 2016) ISSN: 1879-3150 [Electronic] England
• PMID: 27720763 (Publication Type: Journal Article)
• Copyright: Copyright © 2016 Elsevier Ltd. All rights reserved.

Chemical References

• Viper Venoms

Topics

• Animals
• Bradycardia (chemically induced)
• Heart (drug effects)
• Heart Rate (drug effects)
• Hemodynamics (drug effects)
• Hypotension (chemically induced)
• Male
• Myocardium (pathology)
• Rats, Wistar
• Respiratory Rate (drug effects)
• Snake Bites (pathology, physiopathology)
• Viper Venoms (toxicity)
• Viperidae