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5HT3 receptor-mediated vasodilation in the human forearm
G J Blauw1, P van Brummelen, P C Chang
1Department of Nephrology, University Hospital, Leiden, The Netherlands.
Summary
Serotonin (5-hydroxytryptamine, 5HT) causes vasodilation mediated by 5HT3 receptors. A selective 5HT3 antagonist, ICS 205-930, blocked this vascular response in healthy volunteers.
Area of Science:
- Pharmacology
- Vascular Biology
- Neuroscience
Background:
- Serotonin (5-hydroxytryptamine, 5HT) is a neurotransmitter with known vascular effects.
- The specific receptors and pathways involved in 5HT-induced vasodilation require further elucidation.
Purpose of the Study:
- To investigate the role of neuronal 5HT3 receptors in mediating the vascular response to serotonin (5HT).
- To differentiate the vascular effects of 5HT from acetylcholine using selective antagonists.
Main Methods:
- Healthy volunteers received intra-arterial infusions of 5HT and acetylcholine.
- Vascular responses were assessed with and without the 5HT3 antagonist ICS 205-930 and the muscarinic antagonist atropine.
- Forearm blood flow was measured using plethysmography; blood pressure and heart rate were monitored.
Main Results:
- Serotonin (5HT) induced a biphasic increase in forearm blood flow.
- The selective 5HT3 antagonist ICS 205-930 significantly attenuated both phases of the 5HT-induced vasodilation.
- Atropine abolished acetylcholine-induced vasodilation but did not affect the 5HT response.
Conclusions:
- The biphasic vasodilation induced by serotonin (5HT) is mediated by the activation of neuronal 5HT3 receptors.
- These findings highlight the specific role of 5HT3 receptors in regulating vascular tone by serotonin.