Circadian release of serotonin across the coronary bed in patients with endothelial dysfunction

Area of Science:

• Cardiovascular Medicine
• Endocrinology
• Platelet Physiology

Background:

• Endothelial dysfunction is a precursor to cardiovascular disease.
• Serotonin plays a role in vascular function and platelet activity.
• Circadian rhythms influence cardiovascular events and hormone secretion.

Purpose of the Study:

• To investigate transcardiac serotonin differences in nonischemic patients with endothelial dysfunction.
• To determine if these differences exhibit diurnal variation.
• To explore the relationship between serotonin secretion and coronary stenosis.

Main Methods:

• Blood samples were collected from the aorta and coronary sinus.
• Serotonin levels were measured using high-performance liquid chromatography.
• Patients were categorized based on the presence or absence of endothelial dysfunction and coronary stenosis.
• Diurnal variations were assessed by comparing morning and evening samples.

Main Results:

• Transcardiac serotonin levels were significantly higher in nonischemic patients with endothelial dysfunction during the early morning hours.
• A significant difference in transcardiac serotonin was observed between aortic and coronary sinus blood, indicating net release from the heart.
• Platelet serotonin secretion was evident even in the absence of significant coronary stenosis.

Conclusions:

• Early morning transcardiac serotonin release is elevated in nonischemic individuals with endothelial dysfunction.
• Platelet serotonin secretion can occur independently of obstructive coronary artery disease.
• These findings highlight the potential role of platelet-derived serotonin in early cardiovascular pathology and circadian influences on vascular health.