Brain natriuretic peptide (BNP), now known as B-type natriuretic peptide (also BNP) or GC-B, is a 32 amino acid polypeptide secreted by the ventricles of the heart in response to excessive stretching of heart muscle cells (cardiomyocytes). The physiologic actions of BNP are similar to ANP and include decrease in systemic vascular resistance and central venous pressure as well as an increase in natriuresis. proBNP is the prohormone form of BNP. Alternative Names: pro Brain Natriuretic Peptide Protein, NT-proBNP Protein, ProBNP, NPPB Protein