Natriuretic peptides – ANP – BNP – CNP- DNP

Natriuretic peptides – ANP – BNP – CNP- DNP

Initial description of natriuretic peptide was by noting the copious diuresis produced by infusion of extracts of atrial tissue in experimental animals. Later on other natriuretic peptides have been described from different sources. The number of amino acids vary in each natriuretic peptide as follows:
1. Atrial natriuretic peptide (ANP): 28 amino acids
2. Brain natriuretic peptide (BNP): 32 amino acids
3. C- type natriuretic peptide (CNP): 53 amino acids
4. Dendroaspis natriuretic peptide (DNP): 38 amino acids
ANP and BNP are now well known while CNP and DNP are less well known. ANP was described way back in 1981. BNP and NT-pro BNP estimations are now available for clinical applications. Even though the name BNP implies an origin from the brain, human ventricles produce BNP precursor in the form of pro-BNP, which can be cleaved into a C-terminal fragment which is the active BNP and an N-terminal fragment known as NT-proBNP. While BNP has a short half life of 22 minutes, NT-pro BNP has a half life of 120 minutes. That is why the estimation of NT-pro BNP is clinically more useful. BNP estimation for the diagnosis of heart failure has limitations in the presence of advanced kidney disease.

C-type natriuretic peptide is involved in the regulation of vascular tone. Increased production of CNP by the renal tissue has been documented in persons with cirrhosis and functional renal failure [Gut. 2000 December; 47(6): 852–857]. CNP has its origin in the vascular endothelium. CNP has antimitogenic effects and causes relaxation of vascular smooth muscle.

Dendroaspis natriuretic peptide is derived from the venom of the Green Mamba snake, Dendroaspis augusticeps. DNP has recently been discovered in human plasma and atrial myocardium. Elevated levels of DNP have been found in aneurysmal subarachnoid hemorrhage and is thought to mediate the diuresis and natriuresis in these persons [Neurosurgery. 2004 Jul;55(1):69-75]. DNP-like immunoreactivity (DNP-LI) has been reported in human plasma and atrial myocardium and also noted to be elevated in human congestive heart failure.