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Updated: Aug 9, 2026

Gastrointestinal Motility Monitor (GIMM)
Published on: December 1, 2010
5-HT3 receptors augment neuronal, cholinergic contractions in guinea pig trachea
C A Rizzo1, W Kreutner, R W Chapman
1Schering-Plough Research Institute, Kenilworth, NJ 07033-0539.
Abstract:
Serotonin (5-HT) and the selective 5-HT3 receptor agonist, 2-methyl-5-hydroxytryptamine enhanced electrical field stimulated contractions of the isolated guinea pig trachea. 5-HT (EC50 = 3.5 microM) was twice as potent as 2-methyl-5-hydroxytryptamine (EC50 = 7.4 microM). The effects of 5-HT and 2-methyl-5-hydroxytryptamine were antagonized by the selective 5-HT3 receptor antagonist; zacopride (apparent pA2 = 7.60 against 2-methyl-5-hydroxytryptamine). 2-Methyl-5-hydroxytryptamine (10 microM) had no effect on contractile responses to exogenous acetylcholine. Furthermore, the increase in electrical field stimulated contraction by 2-methyl-5-hydroxytryptamine was unchanged by hexamethonium (100 microM) but contractions were blocked by atropine (1 microM). These results suggest that excitatory 5-HT3 receptors exist on postganglionic cholinergic nerves in the isolated guinea pig trachea.
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