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We conclude that (1) BNP is secreted mainly from the left ventricle in normal adult humans as well as in patients with left ventricular dysfunction, whereas ANP is secreted from atria in normal adult humans and also from the left ventricle in patients with left ventricular dysfunction; (2) secretion of BNP as well as ANP from the left ventricle increases in proportion to the severity of the left ventricular dysfunction, suggesting that the secretions of ANP and BNP from the left ventricle are regulated mainly by wall tension of the left ventricle; and (3) the peripheral plasma levels of ANP and BNP reflect the secretion rate of these hormones from the left ventricle and may be used as a marker of the degree of left ventricular dysfunction in patients with left ventricular dysfunction.

IntroductionUsing a specific radioimmunoassay for human brain natriuretic peptide (hBNP) with a monoclonal antibody, we have investigated its synthesis, secretion, and clearance in comparison with those of atrial natriuretic peptide (ANP) in normal subjects and patients with congestive heart failure (CHF Since the discovery of atrial natriuretic peptide (ANP)' in the heart (1-5) and subsequently in the brain (5-10), ANP has been implicated in body fluid homeostasis and blood pressure control as a hormone and as a neuropeptide ( 1-1 1). We and others have previously demonstrated that the synthesis and secretion of ANP in the heart are increased in patients with congestive heart failure (CHF) in relation to its severity (12-18).More recently, brain natriuretic peptide (BNP) was isolated from the porcine brain (19), which has either 26 or 32 amino acid residues, porcine (p) respectively (20), with a remarkable sequence homology to ANP and has peripheral and central actions similar to those of ANP (19,(21)(22)(23). BNP is also synthesized in, and secreted into the circulation from, the porcine heart (24, 25). Subsequently, we and others isolated rat BNP (rBNP) with 45 amino acid residues from the rat heart (26-28). To date, however, the information on BNP in humans is scarce, mainly for lack ofcross-reactivity of human BNP (hBNP) with antisera against pBNP or rBNP.Recently

Neutrophil gelatinase-associated lipocalin (Ngal), also known as siderocalin, forms a complex with ironbinding siderophores (Ngal:siderophore:Fe). This complex converts renal progenitors into epithelial tubules.In this study, we tested the hypothesis that Ngal:siderophore:Fe protects adult kidney epithelial cells or accelerates their recovery from damage. Using a mouse model of severe renal failure, ischemia-reperfusion injury, we show that a single dose of Ngal (10 μg), introduced during the initial phase of the disease, dramatically protects the kidney and mitigates azotemia. Ngal activity depends on delivery of the protein and its siderophore to the proximal tubule. Iron must also be delivered, since blockade of the siderophore with gallium inhibits the rescue from ischemia. The Ngal:siderophore:Fe complex upregulates heme oxygenase-1, a protective enzyme, preserves proximal tubule N-cadherin, and inhibits cell death. Because mouse urine contains an Ngaldependent siderophore-like activity, endogenous Ngal might also play a protective role. Indeed, Ngal is highly accumulated in the human kidney cortical tubules and in the blood and urine after nephrotoxic and ischemic injury. We reveal what we believe to be a novel pathway of iron traffic that is activated in human and mouse renal diseases, and it provides a unique method for their treatment.

We conclude that plasma levels of BNP mainly reflect the degree of ventricular overload and that the secretion patterns of ANP and BNP vary with underlying cardiac disorders of CHF with different degrees of overload in atria and ventricles.

Cardiac fibrosis, defined as a proliferation of interstitial fibroblasts and biosynthesis of extracellular matrix components in the ventricles of the heart, is a consequence of remodeling processes initiated by pathologic events associated with a variety of cardiovascular disorders, which leads to abnormal myocardial stiffness and, ultimately, ventricular dysfunction. Brain natriuretic peptide (BNP) is a cardiac hormone produced primarily by ventricular myocytes, and its plasma concentrations are markedly elevated in patients with congestive heart failure and acute myocardial infarction. However, its precise functional significance has been undefined. In this paper, we report the generation of mice with targeted disruption of BNP (Nppb ؊/؊ mice). We observed multifocal fibrotic lesions in the ventricles from Nppb ؊/؊ mice. No signs of systemic hypertension and ventricular hypertrophy are noted in Nppb ؊/؊ mice. In response to ventricular pressure overload, focal fibrotic lesions are increased in size and number in Nppb ؊/؊ mice, whereas no focal fibrotic changes are found in wild-type littermates (Nppb ؉/؉ mice). This study establishes BNP as a cardiomyocytederived antifibrotic factor in vivo and provides evidence for its role as a local regulator of ventricular remodeling.

We conclude that the plasma level of brain natriuretic peptide is increased markedly in patients with acute myocardial infarction and may reflect the degree of left ventricular dysfunction in these patients.

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