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Direct secretion from left atrium and pulmonary extraction of human atrial natriuretic peptide
M Akaike1, F Ishikura, S Nagata
1Department of Medicine, National Cardiovascular Center, Osaka, Japan.
Insights
High left atrial pressure stimulates direct secretion of human atrial natriuretic peptide (hANP) from the left atrium. The lungs also extract circulating hANP, impacting its levels.
Area of Science:
- Cardiology
- Endocrinology
- Physiology
Background:
- Human atrial natriuretic peptide (hANP) plays a role in cardiovascular homeostasis.
- Understanding the secretion and clearance pathways of hANP is crucial for cardiovascular research.
Purpose of the Study:
- To investigate the direct secretion of hANP from the left atrium.
- To evaluate the pulmonary extraction of hANP.
Main Methods:
- Measurement of plasma hANP levels in the pulmonary artery, pulmonary vein, and left atrium.
- Comparison of hANP levels in patients with mitral stenosis (high left atrial pressure) and atrial septal defect (lower left atrial pressure).
Main Results:
- Left atrial pressure was significantly higher in mitral stenosis patients compared to atrial septal defect patients.
- Elevated hANP levels were observed in the left atrium of mitral stenosis patients.
- Pulmonary hANP levels were lower in the pulmonary vein than the pulmonary artery, indicating pulmonary extraction.
Conclusions:
- hANP is secreted directly from the left atrium, stimulated by elevated left atrial pressure.
- The pulmonary circulation partially extracts circulating hANP.
- These findings elucidate novel secretion and clearance mechanisms for hANP.
Abstract:
To evaluate direct secretion from the left atrium and pulmonary extraction of human atrial natriuretic peptide (hANP), we measured plasma hANP levels in the pulmonary artery, pulmonary vein, and left atrium in patients with either mitral stenosis or atrial septal defect. Left atrial pressure in patients with mitral stenosis was significantly higher than that in patients with atrial septal defect (7.5 +/- 1.0 mm Hg vs 3.1 +/- 0.5 mm Hg, p less than 0.01). The significant increase in the hANP level in the left atrium was recognized only in patients with mitral stenosis (149 +/- 33 pg/ml in the left atrium vs 130 +/- 28 pg/ml in the pulmonary vein, p less than 0.05). The plasma hANP level in the pulmonary vein was significantly lower than that in the pulmonary artery in both patients with mitral stenosis and those with atrial septal defect, which suggests that hANP is extracted in the lung. We conclude that hANP is secreted not only through the coronary sinus but also directly from the left atrium, stimulated by high left atrial pressure, and that circulating hANP is partially extracted in the pulmonary circulation.