An experimental study of cardiac natriuretic peptides as markers of development of congestive heart failure

The use of cardiac peptide measurements as possible diagnostic tools in congestive heart failure has been extensively discussed in the recent literature. Therefore, the aim of this study was to establish a model of experimental chronic heart failure, and thereby perform a comparative study of secretion and circulating levels of the cardiac peptides atrial natriuretic peptide (ANP), N-terminal proatrial natriuretic peptide (N-terminal proANP) and brain natriuretic peptide (BNP) during evolving heart failure. Chronic heart failure was induced in seven pigs by rapid left atrial pacing for three weeks. The effects of failure induction were documented 24 h after pacemaker deactivation. Hemodynamic indices of cardiac preload, like pulmonary capillary wedge pressure (PCWP) and right atrial pressure (RAP), were all considerably increased compared to sham operated controls. Likewise, plasma endothelin-L, noradrenaline, renin activity, aldosterone and angiotensin II were all markedly increased. Heart failure was accompanied by significant increases in both estimated cardiac secretory rate and plasma concentrations of all three cardiac peptides, significantly correlated to the PCWP. The directional changes during evolving heart failure were similar, although the percentage increase in plasma BNP was much larger than for ANP and N-terminal proANP. In absolute molar terms, however, the BNP concentration changes were minor compared to those of the other two peptides. The larger percentage increase of BNP might indicate its superiority as a marker of heart failure development, provided a functional assay suitable for clinical use can be designed for a peptide circulating in this low concentration range.     

Contrasting cardiac regional responses of A-type and B-type natriuretic peptide to experimental chronic heart failure

OBJECTIVE: The aim of this study was to examine the regional myocardial variation in atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) synthesis during development of congestive heart failure (CHF). METHODS: Heart failure was induced by left atrial rapid pacing for 3 weeks in pigs. The gene expression of ANP and BNP was measured by northern blot analysis and the peptide concentration in myocardial tissue and plasma by radioimmunoassay (RIA). RESULTS: At the end of the pacing period pulmonary capillary wedge pressure (PCWP) and right atrial pressure (RAP) increased, and cardiac output (CO) decreased compared to sham-operated controls (PCWP: 17.6 +/- 1.9 vs. 3.1 +/- 0.9 mmHg) (RAP: 10.4 +/- 1.7 vs. 2.2 +/- 0.6 mmHg) (CO: 3.5 +/- 0.4 vs. 5.3 +/- 0.3 l/min), indicating a state of moderate to severe CHF. The gene expression and tissue concentration of BNP was low in sham pigs, but was strongly increased in all cardiac regions, and especially in the left ventricle, during CHF. In contrast, ANP was mainly produced in the atria both in normal and heart failure conditions. The relative increases in mRNA levels, tissue concentrations and circulating peptide concentrations were more profound for BNP than for ANP. CONCLUSIONS: In response to CHF induction, ANP and BNP respond differently across the cardiac regions. Strong expression of the BNP gene was only found in the heart failure state, while ANP was clearly expressed also in the normal state. These findings support the concept of BNP being superior to ANP as a biochemical marker of CHF.     

Gene expression of natriuretic peptides and their receptors type-A and-C after myocardial infarction in rats

The purpose of this study was to investigate myocardial mRNA expression of brain natriuretic peptide (BNP) and atrial natriuretic peptide (ANP) in different regions of the heart at three different time points after induction of myocardial infarction (MI) in rats. Furthermore, we examined putative changes in mRNA expression of natriuretic peptide receptors (NPRs), NPR-A and NPR-C, in myocardium and peripheral organs. Substantial increase in the mRNA levels of both BNP and ANP in the infarcted as well as non-infarcted regions were observed after induction of MI. These findings were paralleled by elevated circulating concentrations of ANP, BNP and N-terminal proANP (Nt-proANP). In addition, the mRNA levels of the clearance receptor, NPR-C, were augmented in the infarcted and non-infarcted regions of the left ventricular wall (LV), while it was decreased in the kidneys and lungs 28 days post-MI. Based on these data, we propose that, in addition to increased myocardial secretion of BNP and ANP, reduced peripheral clearance by NPR-C may contribute to the observed increase in circulating plasma concentrations of the natriuretic peptides after induction of MI in rats.     

Gene expression of natriuretic peptides and their receptors type-A and -C after myocardial infarction in rats

The purpose of this study was to investigate myocardial mRNA expression of brain natriuretic peptide (BNP) and atrial natriuretic peptide (ANP) in different regions of the heart at three different time points after induction of myocardial infarction (MI) in rats. Furthermore, we examined putative changes in mRNA expression of natriuretic peptide receptors (NPRs), NPR-A and NPR-C, in myocardium and peripheral organs. Substantial increase in the mRNA levels of both BNP and ANP in the infarcted as well as non-infarcted regions were observed after induction of MI. These findings were paralleled by elevated circulating concentrations of ANP, BNP and N-terminal proANP (Nt-proANP). In addition, the mRNA levels of the clearance receptor, NPR-C, were augmented in the infarcted and non-infarcted regions of the left ventricular wall (LV), while it was decreased in the kidneys and lungs 28 days post-MI. Based on these data, we propose that, in addition to increased myocardial secretion of BNP and ANP, reduced peripheral clearance by NPR-C may contribute to the observed increase in circulating plasma concentrations of the natriuretic peptides after induction of MI in rats.     

Radioimmunoassay for N-terminal probrain natriuretic peptide in human plasma

Measurement of plasma levels of natriuretic peptides has been used to assess left ventricular dysfunction and prognosis. Recently levels of the N-terminal peptide fragment of the precursor of brain natriuretic peptide have been reported to be present in peripheral plasma and to be increased in chronic heart failure patients. Our aim in this study was to develop a radioimmunoassay for N-terminal proBNP, to compare its plasma concentrations in control subjects and in patients with end-stage heart failure and to define its relation to brain natriuretic peptide (BNP). A polyclonal antibody was raised in rabbits against human N-terminal proBNP fragment (amino acid 1-21). The plasma N-terminal proBNP concentrations were assayed directly without extraction. No detectable cross-reactivity existed with other natriuretic peptides: BNP, ANP or N-terminal proANP. The assay had a detection limit (2 SD from zero) of 9.7 pmol/L. Plasma N-terminal proBNP was 29 (13-75) (median (range)) pmol/L in the control group. There were no gender difference, male: 28 (13-61) vs. female 33 (13-75) pmol/L, p= NS, but there was a positive correlation to age (r=0.52, p<0.0001). In patients with end-stage heart failure the median N-terminal proBNP levels were increased significantly 616 (114-2781) pmol/L (p<0.001) and in pooled data N-terminal proBNP showed a close correlation to BNP (r=0.96, p<0.0001). Size exclusion of plasma extracts indicated that proBNP (1-108) may circulate both as intact prohormone and as split products, N-terminal proBNP (1-76) and BNP (77-108). Our results support the concept that N-terminal proBNP measurement could be a valuable tool in the biochemical indication of increased cardiac wall stress.     

Implications of the natriuretic peptide system in the pathogenesis of heart failure: diagnostic and therapeutic importance

The natriuretic peptide family consists of at least 3 structurally similar peptides: atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP). Under normal conditions, ANP is synthesized by the atrium and released in response to atrial stretch. This peptide plays an important role in sodium and water homeostasis and is involved in cardiovascular function. In contrast, BNP is synthesized primarily by the ventricles, and its circulatory concentrations are significantly elevated in profound congestive heart failure (CHF). While both plasma levels of ANP and BNP have been found to be increased in patients with various heart diseases, the elevation in circulatory BNP correlates better than ANP with the severity of CHF. Therefore, plasma BNP has been suggested (and lately used) to aid in the accurate diagnosis of heart failure in patients admitted to the emergency room with symptoms of decompensated heart failure. Furthermore, circulatory BNP has been utilized as a prognostic marker in CHF as well as a hormone guide in the evaluation of the efficacy of the conventional treatment of this disease state. In light of the cardiovascular and renal effects of BNP, which most likely exceed those of ANP, the former has been used as a therapeutic agent for the treatment of patients with acute severe CHF. Intravenous infusion of BNP into patients with sustained ventricular dysfunction causes a balanced arterial and venous vasodilatation that has been shown to result in rapid reduction in ventricular filling pressure and reversal of heart failure symptoms, such as dyspnea and acute hemodynamic abnormalities. Thus, the goal of this article is to review the physiology and pathophysiology of natriuretic peptides and the potential use of their circulating levels for diagnosis and treatment of heart failure.     

Combined inhibition of angiotensin II and endothelin suppresses the brain natriuretic peptide response to developing heart failure

Blockade of AngII (angiotensin II) and ET (endothelin)-1, established and potential therapeutic strategies respectively, for heart failure, may have an adverse effect on the cardiac secretion of the natriuretic peptides, hormones with actions beneficial in this disease. The present study investigates the roles of AngII and ET-1 in regulating the stretch-induced release of the natriuretic peptides during the development of heart failure. On seven separate days, eight sheep underwent incremental left ventricular pacing (155, 190 and 225 beats/min for 90 min each) with concurrent infusions of a vehicle control, AngII, ET-1, AngII+ET-1, losartan [AT1 (AngII type 1) receptor antagonist], bosentan (ET(A)/ET(B) receptor antagonist) or losartan+bosentan. Pacing-induced rises in LAP (left atrial pressure) were amplified by the simultaneous administration of separate AngII and ET-1, and attenuated following blockade of the peptides, with maximum effects observed during combined treatments. Although these changes in atrial pressure were paralleled by concomitant alterations in circulating levels of both ANP (atrial natriuretic peptide) and BNP (brain natriuretic peptide), the plasma natriuretic peptide/atrial pressure relationship tended to be augmented by AngII and ET-1 and diminished by their blockade. A significant difference was demonstrated between the enhanced plasma BNP response to increasing LAP during combined AngII+ET-1 administration and decreased response during losartan+bosentan treatment ( P <0.05). A similar, but non-significant, trend was evident for ANP. The present study indicates dual AngII/ET-1 blockade diminishes BNP (and to a lesser extent ANP) secretion in developing heart failure, suggesting that augmentation of the natriuretic peptide system during the combination of these therapies may be of benefit.     

Natriuretic peptides in acute and chronic kidney disease and during renal replacement therapy.

Plasma levels of natriuretic peptides are elevated in patients with chronic kidney disease owing to impairment of renal function, hypertension, hypervolemia, and/or concomitant heart disease. Proteinuria and/or immunosuppression also contribute to enhanced plasma levels and increased urinary excretion of natriuretic peptides. Atrial natriuretic peptide (ANP) and particularly brain natriuretic peptide (BNP) levels are linked independently to left ventricular mass and function and predict total and cardiovascular mortality. ANP and BNP decrease significantly during hemodialysis treatment but increase again during the interdialytic interval. Intraperitoneal administration of ANP decreases peritoneal fluid and glucose absorption, as well as lymphatic flow rate. Successful kidney transplant normalizes the plasma levels of natriuretic peptides in the majority of patients. In experimental animals but not in humans, ANP administration protects against ischemic acute renal failure. Since proANP31-67 peptide does not cause hypotension, this vessel dilator may protect the kidney during acute renal failure by intrarenal vasodilation and stimulation of endogenous prostaglandin E2 synthesis.     

Natriuretic peptide system: physiology and clinical utility

PURPOSE OF REVIEW: This review discusses the physiology of natriuretic peptides as a group and brain natriuretic peptide (BNP) in more detail. It will also highlight implications for the use of the natriuretic peptides in the diagnosis and treatment of patients with cardiovascular disease. RECENT FINDINGS: The heart secretes two major natriuretic peptides: atrial natriuretic peptide (ANP), which is synthesized in the atrial myocardium, and BNP, which is synthesized in the ventricular myocardium. Both ANP and BNP are released in response to atrial and ventricular stretch, respectively, and will cause balanced vasodilation, natriuresis, and inhibition of the sympathetic nervous system and the renin-angiotensin-aldosterone axis. BNP is reported to be the biochemical marker of choice for evaluating the acute risk of patients with cardiovascular disease states ranging from heart failure to myocardial ischemia. Increased blood BNP concentrations are highly predictive of the short- and long-term risk of cardiac death across the entire spectrum of acute coronary syndromes and in patients with decompensated congestive heart failure. Synthetic recombinant human BNP, which mimics the actions of endogenous BNP, has emerged as an important new therapeutic agent in patients with acute heart failure. SUMMARY: Current data suggest that single and serial plasma measurement of BNP concentrations is a useful tool in the diagnosis and risk stratification of patients with heart disease. Nesiritide, the human recombinant form of BNP, is a new promising parenteral treatment in decompensated heart failure.     

Cardiac secretion of atrial and brain natriuretic peptides in acuteischaemic heart failure in pigs: effect of angiotensin II receptor antagonism

In amodel of acute ischaemic left ventricular failure in pigs, we compared the plasma levels andcardiac secretion of the three atrial peptides, atrial natriuretic factor (ANF), N-terminalproatrial natriuretic factor (N-terminal proANF) and brain natriuretic peptide (BNP). Acuteischaemic left ventricular failure was induced by embolization of the left coronary artery withplastic microspheres. Thereafter, treatment was given by an intravenous injection of theangiotensin II receptor (AT1) antagonist losartan. Effects of failure induction and treatmentwere documented by measurement of haemodynamic parameters and plasma concentrations ofcatecholamines, plasma renin activity, angiotensin II and aldosterone. Acute left ventricularfailure was accompanied by significant increases in cardiac secretion and plasma levels of allthree atrial peptides, which was considerably more pronounced for ANF and N-terminalproANF than for BNP. Treatment with losartan resulted in significant decreases in plasma ANFand N-terminal proANF, whereas BNP did not change. These findings indicate that ANF andN-terminal proANF may be better suited than BNP as markers of cardiac preload during thedevelopment and treatment of acute heart failure.     

Vasoactive Peptide Release in Relation to Hemodynamic and Metabolic Changes During Rapid Ventricular Pacing

Plasma atrial natriuretic peptide (ANP) concentration increases during ventricular arrhythmias and rapid ventricular pacing but less is known about plasma brain natriuretic peptide (BNP) and endothelin (ET-1). In the present study concentrations of ANP, the amino terminal part of the proANP (NT-proANP), BNP, and ET-1 were measured in the coronary sinus and femoral artery before and at the end of rapid ventricular pacing in 15 patients with coronary arterial disease. The changes were compared with the changes in mean arterial blood pressure, pulmonary capillary wedge pressure (PCWP), transcardiac differences in pH, pCO2, lactate, and norepinephrine. There was an increase in PCWP and a transient decrease in blood pressure after initiation of pacing. Pacing caused a decrease in ST-segment, transcardiac difference of norepinephrine, lactate extraction, pCO2 difference, and an increase in pH difference. Concentration of ANP in the coronary sinus and femoral artery and its transcardiac difference increased during pacing (P < 0.001), whereas changes in NT-proANP were small and BNP and ET-1 levels remained unchanged. The change in transcardiac ANP difference correlated with the change in lactate (r = 0.53, P < 0.05) but not that of norepinephrine, PCWP, or blood pressure. The results show that the plasma concentration of ANP increases more than that of NT-proANP during rapid ventricular pacing. Ischemia-induced release of ANP and its diminished elimination may contribute to the increased plasma ANP level.     

Molecular cloning of hamster brain and atrial natriuretic peptide cDNAs. Cardiomyopathic hamsters are useful models for brain and atrial natriuretic peptides.

Brain and atrial natriuretic peptides (BNP and ANP) are cardiac hormones with diuretic, natriuretic, and vasodilatory activities. Cardiomyopathic hamsters are widely used animal models of heart failure. Due to the structural divergence of BNP among species, examination on pathophysiological roles of BNP using cardiomyopathic hamsters is so far impossible. We therefore isolated hamster BNP and ANP cDNAs, and investigated synthesis and secretion of these peptides in normal and cardiomyopathic hamsters. The COOH-terminal 32-residue peptide of cloned hamster preproBNP with 122 amino acids, preceded by a single arginine residue, supposedly represents hamster BNP showing < 50% homology to rat BNP. Alpha-hamster ANP, 28-residue peptide, is identical to alpha-rat ANP. In hamsters, BNP and ANP occur mainly in the ventricle and the atrium, respectively. The 32-wk-old hypertrophic cardiomyopathic BIO14.6 strain exhibited ventricular hypertrophy. The 32-wk-old dilated cardiomyopathic BIO53.58 strain remained at the stage without apparent heart failure. In BIO14.6 and BIO53.58 strains at this age, ventricular BNP and ANP gene expressions are augmented, and the plasma BNP concentration is elevated to 136 and 108 fmol/ml, respectively, three times greater than the elevated plasma ANP concentration, which well mimics changes of the plasma BNP and ANP concentrations in human heart failure. Cardiomyopathic hamsters, therefore, are useful models to investigate the implication of BNP in human cardiovascular diseases.     

Cardiac natriuretic peptides for cardiac health

The cardiac natriuretic peptides, ANP (atrial natriuretic peptide) and BNP (brain natriuretic peptide), are secreted by the heart in proportion to cardiac transmural pressures. They possess a wide range of effects in multiple tissues facilitating overall pressure/volume homoeostasis. The close relationship between plasma concentrations of these peptides and 'cardiac load' has led to their use as biomarkers of cardiac health with diagnostic and prognostic applications in a variety of disorders affecting the cardiovascular system. BNP and its N-terminal fragment (NT-BNP) are especially sensitive indicators of cardiac dysfunction and remodelling, and correlate strongly with severity. Given that cardiac ischaemia is also an important trigger for the release of these ventricular peptides, they may likewise play a role in the detection of coronary artery disease. Measurement of BNP/NT-BNP shows particular promise as a 'rule out' test for suspected cases of HF (heart failure) in both emergency care and outpatient settings, and may assist in identifying individuals with asymptomatic ventricular impairment who will benefit from therapy preventing progression to overt HF. The BNP peptides also predict subsequent haemodynamic deterioration and adverse events in cardiovascular disease, and can therefore be used to monitor those at high risk and act as a guide to optimization of treatment. The favourable biological properties of the natriuretic peptides have also led to their use as therapeutic agents.     

The circulating levels of cardiac natriuretic hormones in healthy adults: effects of age and sex.

In order to study the relationships between sex hormones, aging, and circulating levels of cardiac natriuretic peptides and to define reference values for atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) assays, we measured the plasma levels of cardiac natriuretic peptides in a large group of healthy adults divided according to age and sex. We studied 216 healthy subjects of both sexes (109 men and 107 women) with age ranging from 20 to 77 years (mean 43.2+/-14.8 years). All subjects were non-obese and had normal arterial blood pressure; they were free from acute diseases, including asymptomatic heart disease. Highly sensitive and specific IRMA methods were used to measure plasma ANP and BNP. The mean ANP value in healthy adult subjects of both sexes was 17.8+/-10.9 pg/ml with no significant difference between men (16.7+/-10.0 pg/ml) and women (18.8+/-11.7 pg/ml). The mean BNP value in healthy adult subjects of both sexes was 9.9+/-9.0 pg/ml with a significant difference (p<0.0001) between men (7.7+/-7.1 pg/ml) and women (12.2+/-10.2 pg/ml). There was a weak linear relationship between age and either ANP (r=0.350, p<0.0001) or BNP (r=0.254, p=0.0002) values. When the circulating levels of cardiac natriuretic hormones, and age and sex were analyzed by multiple stepwise regression analysis, both age and sex significantly and independently contributed to the regression. Our study indicates independent positive effects of aging and female sex hormones on ANP and BNP levels in healthy adult subjects. These effects should be taken into account in the calculation of appropriate reference values for cardiac natriuretic hormones.     

Renal dysfunction is a confounder for plasma natriuretic peptides in detecting heart dysfunction in uremic and idiopathic dilated cardiomyopathies

BACKGROUND: The diagnostic value of natriuretic peptides in uremic cardiomyopathy has not been defined, nor has the effect of a hemodialysis (HD) session on peptides. METHODS: We performed an observational study of 100 white adult outpatients in New York Heart Association class I-II, with neither diabetes nor ischemic heart disease, 50 of whom had idiopathic dilated cardiomyopathy (DCM) and 50 of whom had uremic cardiomyopathy and were undergoing HD. We measured plasma N-terminal proB-type natriuretic peptide (NT-proBNP), BNP, and atrial natriuretic peptide (ANP) both before and after a dialysis session. Doppler echocardiograms were evaluated. We performed multiple regression analysis on the logarithm of peptide concentrations using clinical, laboratory, and echocardio-Doppler data as explanatory variables. RESULTS: Mean peptide concentrations were higher in the HD group, with an HD:DCM ratio of 25 for NT-proBNP and 5 for BNP and ANP. Peptides were correlated with each other (r > 0.85). After HD, NT-proBNP significantly increased by 14%, BNP decreased by 17%, and ANP decreased by 56%. Predialysis concentrations correlated with postdialysis values (r > 0.85). A multiple regression equation significantly fitted the observed peptide concentrations, both pre- and postdialysis, using the same set of 4 variables: disease group (DCM or HD), diastolic pattern, left atrial volume, and body mass index. CONCLUSIONS: Renal dysfunction was a confounder for natriuretic peptides, which were present in higher concentrations in the uremic patients with milder cardiac dysfunction than in those with idiopathic DCM without renal dysfunction. Left diastolic function pattern and atrial volume were cardiac determinants of peptide concentrations in DCM and HD.     

ProBNP-derived peptides in cardiac disease

The natriuretic peptides constitute a family of structurally related peptides that regulate fluid homeostasis, vascular tonus and growth. After the discovery of an endocrine component of the heart almost 25 years ago, the cardiac natriuretic peptides have now been fully accepted as useful markers in diverse aspects of cardiology including as diagnostic, therapeutic and prognostic markers of cardiac disease. In humans, atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) are mainly synthesized and secreted by the failing heart, whereas the related C-type natriuretic peptide (CNP) appears to be a local regulatory peptide secreted by the vascular endothelium. Accordingly, CNP is not a cardiac peptide. With the recent implementation of sensitive and specific immunoassays, increased plasma concentrations of proBNP-derived peptides have now been associated with several cardiac conditions, where the major application today seems related to ventricular dysfunction. Recently, focus has also turned to ischemic heart disease, since myocardial hypoxia increases the local BNP gene expression. This review recapitulates the established clinical applications of measuring proBNP-derived peptides in plasma. Furthermore, the evidence of increased cardiac BNP expression in ischemic heart disease will be emphasized. In turn, plasma measurement of proBNP-derived peptides may still hold new possibilities in screening for coronary artery disease.     

ProBNP‐derived peptides in cardiac disease

The natriuretic peptides constitute a family of structurally related peptides that regulate fluid homeostasis, vascular tonus and growth. After the discovery of an endocrine component of the heart almost 25 years ago, the cardiac natriuretic peptides have now been fully accepted as useful markers in diverse aspects of cardiology including as diagnostic, therapeutic and prognostic markers of cardiac disease. In humans, atrial natriuretic peptide (ANP) and B‐type natriuretic peptide (BNP) are mainly synthesized and secreted by the failing heart, whereas the related C‐type natriuretic peptide (CNP) appears to be a local regulatory peptide secreted by the vascular endothelium. Accordingly, CNP is not a cardiac peptide. With the recent implementation of sensitive and specific immunoassays, increased plasma concentrations of proBNP‐derived peptides have now been associated with several cardiac conditions, where the major application today seems related to ventricular dysfunction. Recently, focus has also turned to ischemic heart disease, since myocardial hypoxia increases the local BNP gene expression. This review recapitulates the established clinical applications of measuring proBNP‐derived peptides in plasma. Furthermore, the evidence of increased cardiac BNP expression in ischemic heart disease will be emphasized. In turn, plasma measurement of proBNP‐derived peptides may still hold new possibilities in screening for coronary artery disease.     

Cardiac natriuretic hormones, neuro-hormones, thyroid hormones and cytokines in normal subjects and patients with heart failure.

The derangement of neuro-endocrine control of circulation influences both disease evolution and response to treatment in patients with heart failure, but little data are available about the complex relationships between the degree of neuro-hormonal activation and clinical severity. We studied the relationships between cardiac natriuretic hormones (CNHs) and several neuro-hormones and immunological markers in a prospective cohort of 105 consecutive patients with cardiomyopathy (77 men and 28 women, mean age 66.7+/-12.4 years, range 33-89 years). We assayed the circulating levels of CNHs (atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP)), plasma renin activity (PRA), aldosterone, cortisol, adrenaline, noradrenaline, thyroid hormones and thyroid stimulating hormone (TSH), tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). The concentrations of all CNHs and neurohormones were higher in patients with heart failure compared to normal subjects, except for free triiodothyronine (FT3), which was below normal values. ANP was positively related to NYHA class, IL-6, adrenaline, noradrenaline and cortisol, while negatively with ejection fraction and FT3. BNP was positively related to age, NYHA class, IL-6, TNF-alpha, adrenaline, noradrenaline and cortisol, while negatively with ejection fraction and FT3. A stepwise multiple linear regression indicated that plasma ANP depended only on ejection fraction, adrenaline and noradrenaline values, while for plasma BNP variation NYHA class contributed too. Our data confirm a progressive activation of hormonal and immunological systems in patients with heart failure. Furthermore, CNH circulating levels in heart failure are affected not only by cardiac function and disease severity, but also by activation of neuro-hormonal and stress-related cytokine systems, as well as by the thyroid hormones, even on usual medical treatment.