A hormone (chemical messenger) that is produced by the atria (upper chambers) of the heart to regulate blood pressure and fluid balance by its action on the kidneys. The name “atrial” comes from the hormone’s origin in the cells of the atria and “natriuretic” refers to its role in excreting sodium in the urine.
The atria of the heart contain peptides (a combination of amino acids) with potent diuretic and vasodilating properties. Plasma concentration of immunoreactive atrial natriuretic peptide can now be measured: the levels are low in healthy subjects and are increased in patients with congestive heart failure. Infusion of the peptides reduces blood pressure and causes a natriuresis and diuresis.
Atrial natriuretic peptide is a substance generated within specialized cells located in the muscular wall of the atria, which are the upper chambers of the heart. In response to atrial muscle enlargement caused by conditions like heart failure or hypertension (high blood pressure), atrial natriuretic peptide is released into the bloodstream. This peptide plays a role in regulating fluid balance, blood pressure, and electrolyte levels within the body.
Atrial natriuretic peptide promotes the excretion of sodium in the urine, resulting in increased sodium levels being eliminated from the body. As sodium is expelled, water follows suit, leading to a decrease in blood volume. This reduction in blood volume subsequently contributes to the lowering of blood pressure.
Children born with congenital heart disorders leading to heart disease exhibit elevated levels of atrial natriuretic peptide. However, after undergoing successful corrective surgery to address the underlying heart abnormality, the levels of atrial natriuretic peptide gradually decline. This decrease in atrial natriuretic peptide levels is indicative of the improved heart function and the successful resolution of the congenital heart disorder.