Vasoactivity of the Rhinela marina toad poison in aorta of Wistar rats

Vasoactivity of the Rhinela marina toad poison in aorta of Wistar rats

• Autor
• Cintia Vieira dos Santos
• Co-autores
• Angélica Macedo Borges Paulino , Bianca Sulzbacher da Silva , Jacqueline Kerkhoff Richoppo , Adilson Paulo Sinhorin , Fernando Silva Carneiro , Gisele Facholi Bomfim
• Resumo

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  Background: Rhinella marina toad is very abundant in Brazil. Its poison has a large amount of bufadienolides, which are substances with great biological action. Our aim was to characterize the vasoactivity of this poison in the aorta of male Wistar rats. Methods: The poison was collected and processed. The alcoholic extract obtained was used in the experiments. Concentration-response curves were performed in segments of thoracic aorta (with and without endothelium) to R. marina poison extract and its isolated compound, marinobufagenin. The mechanisms involved and the NA+ /K+ ATPase activity were also evaluated. The mean and standard error were calculated. The groups were compared using one-way ANOVA. CEUA n° 23108.703779/14-6. Results: The poison was effective in promote vasoconstriction (EC50 = 0,2085M e Rmax = 117,9±3,2 %KCl). In the absence of endothelium, the vessel presented almost twice the contractility (Rmax = 211,6±12 %KCl). Nitric oxide participates of the endothelial modulation since the inhibition of eNOS, by L-NAME, increased the contractile response (Rmax = 161,6±19,6 %KCl). About the mechanisms of action, we observed that the segments incubated with losartan (AT1 receptors antagonist), nifedipine (L-type calcium channels blocker), ketanserin (5-HT receptors antagonist) and prazosin (?1-adrenergic receptor antagonist) showed a decrease in contractility, about 59%, 57%, 45% e 46%, respectively. There was no change in the contractile response in the presence of cyclooxygenase (indomethacin) and reactive oxygen species (apocynin) pathway blockers. At NA+ /K+ ATPase test, the aortas incubated with poison presented 24% higher vascular relaxation than the control, indicating that the poison acts increasing the effect of tissue repolarization. Marinobufagenin compound showed no vasoactive response. Conclusions: The poison of the toad Rhinella marina has a potent vasoconstrictive action, not associated with bufadienolides, and may be a possible candidate for the treatment of vascular diseases, as sepsis.

• Palavras-chave
• Rhinella marina, aorta, amphibian poisons
• Modalidade
• Pôster
• Área Temática
• Produtos naturais