Sandro Rostelato-Ferreira
1,2* ![ORCID logo](/image/orcid.png)
, Cháriston André Dal Belo
3 ![ORCID logo](/image/orcid.png)
, Pedro Ismael da Silva Junior
4 ![ORCID logo](/image/orcid.png)
, Stephen Hyslop
1 ![ORCID logo](/image/orcid.png)
, Léa Rodrigues-Simioni
1, Thomaz Augusto Alves Rocha-e-Silva
5
1 Departamento de Farmacologia, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Zip Code 13083-970, Campinas, SP, Brazil.
2 Instituto de Ciências da Saúde, Universidade Paulista (UNIP), Zip Code 18087-101, Sorocaba, SP, Brazil.
3 Centro de Ciências Rurais de São Gabriel, Universidade Federal do Pampa (UNIPAMPA), São Gabriel, RS, Brazil.
4 Laboratório Especial de Toxinologia Aplicada, Instituto Butantan, São Paulo, SP, Brazil.
5 School of Medicine Faculdade Israelita de Ciências da Saúde Albert Einstein, São Paulo, SP, Brazil.
Abstract
Purpose: 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. Methods: The methanolic extract from R. schneideri poison was fractioned by reversed phase HPLC. The purity and molecular mass were determined by LC/MS mass spectrometry. Chick biventer cervicis and mouse phrenic-nerve diaphragm were used as neuromuscular preparations to identify the toxin. Results: The purification resulted in 32 fractions, which 4 of them were active in neuromuscular preparation. The toxin of fraction 20 were chosen for better reproducibility of the whole extract activity and its molecular mass was 730.6 Da. The toxin produced facilitation of the muscle contraction followed by a complete neuromuscular blockade in chick biventer cervicis preparation in 90 min without interfering with the exogenous response to ACh and KCl. The quantal content was increased from 128 ± 13 (control) to 216 ± 44 (after 5 min and sustained until 60 min) in the presence of the toxin. Conclusion: In conclusion, our results demonstrated that the neuromuscular action of the poison of Rhinella schneideri is a multitoxin effect. More, the present work first isolated a 730.6 Da toxin that better represent the whole poison neuromuscular effect, to which is attributed a presynaptic action in avian and mouse neuromuscular preparation.