Brain Natriuretic Peptides（BNP）

Brain natriuretic peptide (BNP), also known as B-type natriuretic peptide, is a hormone released by cardiomyocytes in the heart ventricles because of the ventricular blood volume increases causing stretching. BNP was originally described from porcine brain tissue, but later it was found to mainly originate from the heart. It is a member of the natriuretic peptide family along with ANP and CNP, two additional peptides with similar structures. Their shared molecular structure consisted of a 17-amino acid ring and a disulfide bridge between two cysteine molecules.

In cardiomyocytes, BNP is synthesized as a 108 amino acids peptide called pro-BNP, which is cleaved into 32 amino acids of active BNP and biologically inactive N-terminal fragment (NT-proBNP) containing 72 amino acids. Similar to ANP but with a 10-fold lower affinity, BNP interacts with the atrial natriuretic factor receptor NPRA in the systemic circulation to mediate a variety of biological effects. However, BNP is twice the biological half-life of ANP, and NT-proBNP is even longer, hence these peptides are more suitable targets for diagnostic blood testing than ANP.