Brain natriuretic peptide, also known as B-type natriuretic peptide, is a cardiac peptide hormone involved in blood-volume regulation, vascular adaptation, sodium balance, and coordination of cardiovascular-endocrine signaling pathways. BNP functions as an important endocrine signal released by cardiac tissue during increased ventricular wall stress and circulatory load.
The hormone promotes sodium excretion, enhances renal water elimination, relaxes vascular smooth muscle, and suppresses renin-angiotensin-aldosterone system activity. BNP also contributes to regulation of cardiac workload, ventricular pressure adaptation, extracellular fluid balance, and communication between the heart and kidneys. Through these actions, the hormone helps coordinate cardiovascular stability and fluid-volume regulation across multiple organ systems.
BNP is produced primarily by ventricular cardiomyocytes within the heart. The hormone is synthesized as a precursor peptide that undergoes enzymatic cleavage into biologically active BNP and associated peptide fragments before release into circulation.
Production increases substantially during ventricular stretching, increased cardiac pressure, elevated blood volume, and hemodynamic stress. Cardiac tissue therefore functions not only as a mechanical pump but also as an endocrine organ capable of rapidly responding to circulatory changes.
BNP secretion is regulated mainly by ventricular wall tension, fluid-volume expansion, blood-pressure signaling, and cardiovascular stress pathways. Increased myocardial stretch strongly stimulates production and release from ventricular tissue.
The hormone acts through natriuretic peptide receptor systems linked to cyclic GMP signaling, renal sodium-handling pathways, vascular smooth muscle relaxation mechanisms, and suppression of renin and aldosterone signaling. Sympathetic nervous-system activity, fluid-electrolyte balance, and endocrine cardiovascular communication pathways also influence secretion dynamics. Through these integrated cardiovascular-endocrine systems, BNP coordinates sodium balance, vascular regulation, cardiac adaptation, and extracellular fluid homeostasis.
BNP signals the kidneys and vasculature to excrete sodium and water and adjust vascular tone as needed.
