Abstract-Dendroaspis natriuretic peptide (DNP), a recently discovered peptide, shares structural similarity to the other known natriuretic peptides, ANP, BNP, and CNP. Studies have reported that DNP is present in human and canine plasma and atrial myocardium and increased in plasma of humans with congestive heart failure (CHF). In addition, synthetic DNP is markedly natriuretic and diuretic and is a potent activator of cGMP in normal animals. To date, the ability of synthetic DNP to improve cardiorenal function in experimental CHF is unknown. Synthetic DNP was administered intravenously at 10 and 50 ng · kg Ϫ1 · min Ϫ1 in dogs (nϭ7) with severe CHF induced by rapid ventricular pacing for 10 days at 245 bpm. In addition, we determined endogenous DNP in normal (nϭ4) and failing (nϭ4) canine atrial and ventricular myocardium. We report that administration of synthetic DNP in experimental severe CHF has beneficial cardiovascular, renal, and humoral properties. First, DNP in CHF decreased cardiac filling pressures, specifically right atrial pressure and pulmonary capillary wedge pressure. Second, DNP increased glomerular filtration rate in association with natriuresis and diuresis despite a reduction in mean arterial pressure. Third, DNP increased plasma and urinary cGMP and suppressed plasma renin activity. Fourth and finally, we report that DNP immunoreactivity is present in canine atrial and ventricular myocardium and increased in CHF. These studies report the acute intravenous actions of synthetic DNP in experimental severe CHF and suggest that on the basis of its beneficial properties, DNP may have potential as a new intravenous agent for the treatment of decompensated CHF. Key Words: heart failure Ⅲ natriuretic peptides Ⅲ cyclic guanosine monophosphate Ⅲ renin Ⅲ endopeptidase A s the prevalence of congestive heart failure (CHF) has increased during the past decade, so has hospitalization for acutely decompensated CHF. 1 This has resulted in a continued search for new therapeutic agents to treat CHF, including intravenous agents for acutely decompensated CHF, which is characterized by markedly elevated cardiac filling pressure with pulmonary congestion, impaired glomerular filtration rate (GFR) with sodium retention, and activation of the renin-angiotensin-aldosterone system.Recently, a new member of the natriuretic peptide family, Dendroaspis natriuretic peptide (DNP), has been reported. 2 DNP, originally isolated from the venom of the Dendroaspis angusticeps (green mamba snake), is a 38-amino-acid peptide that contains a 17-amino-acid disulfide ring structure with 15-residue C-terminal extension. This peptide, which shares structural similarity to atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP), potently vasorelaxes isolated precontracted rodent aorta and canine coronary arteries and augments the formation of 3Ј,5Ј cyclic guanosine monophosphate (cGMP) in aortic endothelial and smooth muscle cells. 2,3 We have reported that DNP immunoreactivity is present...