Abstract
5-Hydroxytryptamine (5-HT) induced concentration-related relaxations (EC50 = 9.1 microM) of guinea-pig proximal colon pretreated with ketanserin (1 microM) and ondansetron (10 microM). This 5-HT-induced effect was neuronally mediated since it was blocked by tetrodotoxin (0.3 microM). 5-Carboxamidotryptamine was a full agonist and ten times more potent than 5-HT. alpha-Methyl-5-HT was a partial agonist. 2-Methyl-5-HT was without effect. Methysergide and metergoline were antagonists of 5-HT producing parallel shifts at 0.1 microM but unsurmountable antagonism at higher concentrations. pKB values of 8.0 and 7.3 were calculated for methysergide and metergoline, respectively. This study has identified a 5-HT-induced relaxation of guinea-pig proximal colon which is mediated via a neuronal 5-HT1-like receptor. However, the subtype has yet to be established.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.