Related Experiment Video
Updated: Jul 25, 2026

Mesenteric Artery Contraction and Relaxation Studies Using Automated Wire Myography
Published on: September 22, 2011
5-HT4 receptor activation induces relaxation and associated cAMP generation in rat esophagus
C Moummi1, D C Yang, G W Gullikson
1Division of Gastrointestinal Diseases, Searle Research and Development, Stokie, IL 60077.
Abstract:
Changes in mechanical events and intracellular levels of cAMP induced by the activation of the 5-HT4 receptor were investigated in the rat esophagus tunica muscularis mucosae preparation. Serotonin (5-HT) and 5 methoxytryptamine (5-MOT; 5-HT4 agonist) caused concentration-related relaxation responses, while 5-carboxamidotryptamine (5-CT; 5-HT1 agonist), 1-(2,5-dimethoxy-4-iodophenyl)-2-amino-propane (DOI; 5-HT2 agonist) and 2-methyl-serotonin (2-methyl-5-HT; 5-HT3 agonist) were less active. The prokinetic agents, cisapride and renzapride also induced concentration-dependent relaxation of rat esophagus which was intermediate to 5-HT and 5-MOT in potency. The relaxation was not due to activity at receptors other than the 5-HT4 since methysergide (5-HT1 and 5-HT2 antagonist) and granisetron (5-HT3 antagonist) did not block the relaxant response to 5-HT while ICS 205930 (5-HT4 antagonist) antagonized this response (pA2 = 6.45). Serotonin also caused concentration-related increases in tunica muscularis mucosae cAMP with the rank order of efficacy of 5-HT agonists in raising tissue cAMP levels reflecting their relaxant activities (5HT greater than or equal to 5-MOT greater than 5-CT greater than DOI = 2-methyl-5-HT = control). Enhancement of cAMP concentrations was also observed following renzapride treatment. This cAMP relaxation response was specific for 5-HT4 receptor activation as demonstrated by the lack of ICS 205930 inhibition of rat esophagus relaxation caused by isoproterenol, 16,16-dimethyl-prostaglandin E2 and forskolin.(ABSTRACT TRUNCATED AT 250 WORDS)
Related Concept Videos
G-Protein Gated Ion Channels
Sensory organs,...
GPCRs Regulate Adenylyl Cylase Activity
Two...
Nitric Oxide Signaling Pathway
Cholinergic Receptors: Muscarinic
The subtypes M1, M3, and M5 couple with the Gq subunit and activate the phospholipase C (PLC) activity, mobilizing intracellular Ca2+. Activation...
Parasympathetic Signaling
The effects of...
Esophageal Achalasia

