Vascular contractions to serotonin are augmented by cooling

Area of Science:

• Vascular pharmacology
• Cardiovascular research
• Physiology

Background:

• Serotonin (5-HT) is a key mediator of vascular tone.
• Cold exposure can trigger vasospasm, but underlying mechanisms are not fully understood.
• The role of temperature in modulating 5-HT-induced vascular responses requires further investigation.

Purpose of the Study:

• To investigate the effect of acute moderate cooling on vascular reactivity in human saphenous veins (HSV) and rat tail arteries (RTA).
• To determine if temperature influences serotonin (5-HT)-mediated contractions via S2 receptors.
• To explore the potential clinical implications for cold-induced vasospasm.

Main Methods:

• Isometric tension recordings were performed on isolated rings of HSV and RTA.
• Vascular responses to potassium chloride (KCl) and serotonin (5-HT) were measured at different temperatures (37°C and 24°C).
• The effects of alpha-adrenoceptor blockade and S2-selective 5-HT antagonist (ketanserin) were assessed.

Main Results:

• Cooling did not significantly affect resting tension or KCl-induced contractions.
• Serotonin (5-HT) elicited concentration-dependent contractions in both HSV and RTA, mediated by S2 receptors.
• Acute moderate cooling significantly augmented 5-HT-induced contractions in both vascular preparations.

Conclusions:

• Acute moderate cooling potentiates S2-receptor-mediated vascular contractions induced by serotonin.
• Temperature-dependent enhancement of serotonergic responsiveness may contribute to vasospasm in cold conditions.
• Findings highlight a potential mechanism linking environmental temperature to cardiovascular events.