Biochemistry of Pro-B-Type Natriuretic Peptide-Derived Peptides: The Endocrine Heart Revisited

BACKGROUND: Since the discovery of cardiac hormones almost 25 years ago, a vast amount of clinical research has identified the cardiac natriuretic peptides and their precursors as markers of heart failure. It even seems likely that the pro-B-type natriuretic peptide (proBNP)-derived peptides in plasma may become the most frequently measured peptides in the daily diagnosis and control of therapy. In contrast, the biochemistry of the peptides has received less attention. METHODS: Published data available on the National Library of Medicine (NLM) were used as the basis for the review. OUTCOME: This review shows that the present understanding of the biochemistry of peptides is far from complete. In particular, cellular synthesis, including posttranslational precursor maturation, is poorly understood. Moreover, elimination of the precursor fragments is unknown. Elucidation of the molecular heterogeneity of proBNP products will therefore contribute to the understanding of the endocrine heart and may also have important diagnostic consequences. Above all, the different proBNP-derived peptides may not always be equal markers of the same pathophysiologic processes. A different metabolism and peripheral elimination may also impose new and peptide-specific limitations for diagnostic use. CONCLUSIONS: It is necessary to focus more on the biology of the proBNP-derived peptides. In turn, new insight into the biochemistry could pave the way for more sensitive and disease-specific assays in the clinical setting.