Abstract
Previously, we demonstrated that caulerpine has spasmolytic effect on guinea pig ileum. The aim of this study was to investigate pathways of its spasmolytic action. We test caulerpine against phasic contractions induced by carbachol in the circular layer of guinea pig ileum and this alkaloid did not inhibit these contractions, indicating that caulerpine did not interfering with the mobilisation of Ca2+ from intracellular stores. Additionally, the spasmolytic effect of caulerpine did not involve K+ channels. Furthermore, we observed that α2-adrenergic receptors were not involved in the spasmolytic effect of caulerpine, since the relaxation curve induced by caulerpine was not shifted in the presence of yohimbine (α2-adrenergic antagonist). However, in the presence of propranolol (β-adrenergic antagonist), the relaxation curve induced by caulerpine was right-shifted, resulting in a fivefold increase in EC50. Thus, a possible mechanism for the spasmolytic action of caulerpine is the activation of β-adrenergic receptors.
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Acknowledgements
The authors thank their colleagues working at the ‘Universidade Federal da Paraíba’ and ‘Universidade Federal de Alagoas’ for their constructive criticism and assistance in carrying out this project. Dr A. Leyva helped with English editing of the manuscript.
Disclosure statement
The authors declare no conflict of interest.
Funding
The authors are grateful to the ‘Universidade Federal da Paraíba’, CAPES, MCT, FINEP, FAPEAL [Pronem 20110722-006-0018-0010], CNPQ [479822/2013-1], CNPQ [404344/2012-7], INCT-INOFAR/CNPq [573.564/2008-6], PRONEX/FAPESQ-PB, INCTAmbTropic and the Ministry of Environment [License MMA/CGEN 18/2007] for the joint funding of this research project.