Natriuretic peptides and therapeutic applications

Ularitide for the treatment of acute decompensated heart failure: from preclinical to clinical studies

The short- and long-term morbidity and mortality in acute heart failure is still unacceptably high. There is an unmet need for new therapy options with new drugs with a new mode of action. One of the drugs currently in clinical testing in Phase III is ularitide, which is the chemically synthesized form of the human natriuretic peptide urodilatin. Urodilatin is produced in humans by differential processing of pro-atrial natriuretic peptide in distal renal tubule cells. Physiologically, urodilatin appears to be the natriuretic peptide involved in sodium homeostasis. Ularitide exerts its pharmacological actions such as vasodilation, diuresis, and natriuresis through the natriuretic peptide receptor/particulate guanylate cyclase/cyclic guanosine monophosphate pathway. In animal models of heart failure as well as Phase I and II clinical studies in heart failure patients, ularitide demonstrated beneficial effects such as symptom relief and vasodilation, while still preserving renal function. Subsequently, the pivotal acute decompensated heart failure (ADHF) Phase III study, called TRUE-AHF, was started with the objectives to evaluate the effects of ularitide infusion on the clinical status and cardiovascular mortality of patients with ADHF compared with placebo. This review summarizes preclinical and clinical data supporting the potential use of ularitide in the treatment of ADHF.

Impaired sinoatrial node function and increased susceptibility to atrial fibrillation in mice lacking natriuretic peptide receptor C

Natriuretic peptides (NPs) are critical regulators of the cardiovascular system that are currently viewed as possible therapeutic targets for the treatment of heart disease. Recent work demonstrates potent NP effects on cardiac electrophysiology, including in the sinoatrial node (SAN) and atria. NPs elicit their effects via three NP receptors (NPR-A, NPR-B and NPR-C). Among these receptors, NPR-C is poorly understood. Accordingly, the goal of this study was to determine the effects of NPR-C ablation on cardiac structure and arrhythmogenesis. Cardiac structure and function were assessed in wild-type (NPR-C(+/+)) and NPR-C knockout (NPR-C(-/-)) mice using echocardiography, intracardiac programmed stimulation, patch clamping, high-resolution optical mapping, quantitative polymerase chain reaction and histology. These studies demonstrate that NPR-C(-/-) mice display SAN dysfunction, as indicated by a prolongation (30%) of corrected SAN recovery time, as well as an increased susceptibility to atrial fibrillation (6% in NPR-C(+/+) vs. 47% in NPR-C(-/-)). There were no differences in SAN or atrial action potential morphology in NPR-C(-/-) mice; however, increased atrial arrhythmogenesis in NPR-C(-/-) mice was associated with reductions in SAN (20%) and atrial (15%) conduction velocity, as well as increases in expression and deposition of collagen in the atrial myocardium. No differences were seen in ventricular arrhythmogenesis or fibrosis in NPR-C(-/-) mice. This study demonstrates that loss of NPR-C results in SAN dysfunction and increased susceptibility to atrial arrhythmias in association with structural remodelling and fibrosis in the atrial myocardium. These findings indicate a critical protective role for NPR-C in the heart.

Cell surface protein disulfide isomerase regulates natriuretic peptide generation of cyclic guanosine monophosphate

Rationale

The family of natriuretic peptides (NPs), including atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), and C-type natriuretic peptide (CNP), exert important and diverse actions for cardiovascular and renal homeostasis. The autocrine and paracrine functions of the NPs are primarily mediated through the cellular membrane bound guanylyl cyclase-linked receptors GC-A (NPR-A) and GC-B (NPR-B). As the ligands and receptors each contain disulfide bonds, a regulatory role for the cell surface protein disulfide isomerase (PDI) was investigated.

Objective

We utilized complementary in vitro and in vivo models to determine the potential role of PDI in regulating the ability of the NPs to generate its second messenger, cyclic guanosine monophosphate.

Methods and Results

Inhibition of PDI attenuated the ability of ANP, BNP and CNP to generate cGMP in human mesangial cells (HMCs), human umbilical vein endothelial cells (HUVECs), and human aortic smooth muscle cells (HASMCs), each of which were shown to express PDI. In LLC-PK1 cells, where PDI expression was undetectable by immunoblotting, PDI inhibition had a minimal effect on cGMP generation. Addition of PDI to cultured LLC-PK1 cells increased intracellular cGMP generation mediated by ANP. Inhibition of PDI in vivo attenuated NP-mediated generation of cGMP by ANP. Surface Plasmon Resonance demonstrated modest and differential binding of the natriuretic peptides with immobilized PDI in a cell free system. However, PDI was shown to co-localize on the surface of cells with GC-A and GC-B by co-immunoprecpitation and immunohistochemistry.

Conclusion

These data demonstrate for the first time that cell surface PDI expression and function regulate the capacity of natriuretic peptides to generate cGMP through interaction with their receptors.

The effects of vasonatrin peptide on random pattern skin flap survival

BACKGROUND

A lot of methods have been intensively investigated to improve random skin flap survival. Decreasing inflammation and alleviating tissue injury have been reported to be effective in improving survival ratio. Vasonatrin peptide (VNP) is a chimera of atrial natriuretic peptide (ANP) and C-type natriuretic peptide (CNP). The current study demonstrates that VNP possesses the venodilating actions of CNP, the natriuretic actions of ANP, and the unique arterial vasodilating actions not associated with either ANP or CNP. However, its effects on skin flap survival have not been previously reported.

METHODS

Sprague-Dawley rats, weighing 220 to 260 g, were randomly divided into 2 groups, namely, the VNP-treated group and the control group. Rectangular random dorsal skin flaps measuring 3 × 9 cm including the panniculus carnosus were elevated, then the flaps were sutured into their original places. In the VNP group, 0.1 mg/kg of VNP was administered intravenously (IV) after surgery and then daily for 3 days. In the control group, 1 mL/kg of saline was administered IV after surgery and then daily for 3 days. To observe the effects of VNP, blood perfusion, histopathological examination, the inflammatory mediators (tumor necrosis factor α, interleukin 1β, and interferon γ), and biochemical analysis (malondialdehyde, glutathione, and myeloperoxidase) were detected and the flap viability was evaluated 7 days after surgery by measuring necrotic flap area and total flap area.

RESULTS

The viability measurements showed the percentage of flap survival was increased in the VNP-treated group (76.53% ± 6.36%) as compared with the control group (61.12% ± 4.92%) (P < 0.05), and the histological and biochemical assays corroborated the data. The blood perfusion of flaps in the VNP-treated group was higher than the control group (P < 0.05). The inflammatory mediators (tumor necrosis factor α, interleukin 1β, and interferon γ) were significantly lower in the VNP-treated group than the control group (P < 0.05).

CONCLUSIONS

This study found that VNP, which could elevate the tissue blood perfusion and mitigate the tissue damage and inflammatory reaction, is associated with a higher percentage of survival random pattern skin flap area.

Atrial natriuretic peptide (ANP) inhibits DMBA/croton oil induced skin tumor growth by modulating NF-κB, MMPs, and infiltrating mast cells in swiss albino mice

Cardiac hormone atrial natriuretic peptide (ANP) and its receptor, natriuretic peptide receptor-A (NPR-A) are implicated as a vital regulator of cancer cell growth and tumor progression. However, the underlying mechanism by which ANP opposes the cancer growth in in-vivo remains unknown. Herein, we investigated the anti-cancer activity of ANP on 7, 12-dimethyl benzanthracence (DMBA)/Croton oil- induced two-step skin carcinogenic mouse model. Skin tumor incidence and tumor volume were recorded during the experimental period of 16 weeks. ANP (1 μg/kg body weight/alternate days for 4 weeks) was injected subcutaneously from the 13th week of DMBA/Croton oil induction. ANP treatment markedly inhibited the skin tumor growth (P<0.001). A significant reduction in the level of NF-κB activation (P<0.001), infiltrating mast cell count (P<0.01) and MMP-2/-9 (P<0.001, respectively) were noticed in the ANP treated mice skin tissue. Further, ANP treatment revert back the altered levels of serum LDH-4, C-reactive protein (CRP), and enzymatic antioxidants (SOD and CAT activities) to near normal level. Taken together, the results of this study suggest that ANP opposes the skin carcinogenesis by suppressing the inflammatory response and MMPs.

Clinical Significance of B-type Natriuretic Peptide in Heart Failure

Biochemical tests to detect B-type natriuretic peptide (BNP) or N-terminal pro-brain BNP (NT-proBNP) are useful diagnostic methods for patients with possible HF. These tests are valuable prognostic predictors for the entire spectrum of HF disease severity. Therefore, the measurements of BNP or NT-proBNP taken along with conventional clinical assessments may assist clinicians in deciding treatment. The following review briefly summarizes the available information regarding the clinical significance of BNP and NT-proBNP.

Natriuretic peptides in cardiovascular diseases: current use and perspectives

The natriuretic peptides (NPs) family, including atrial, B-type, and C-type NPs, is a group of hormones possessing relevant haemodynamic and anti-remodelling actions in the cardiovascular (CV) system. Due to their diuretic, natriuretic, vasorelaxant, anti-proliferative, and anti-hypertrophic effects, they are involved in the pathogenic mechanisms leading to major CV diseases, such as heart failure (HF), coronary artery disease, hypertension and left ventricular hypertrophy, and cerebrovascular accidents. Blood levels of NPs have established predictive value in the diagnosis of HF, as well as for its prognostic stratification. In addition, they provide useful clinical information in hypertension and in both stable and unstable coronary artery disease. Structural abnormalities of atrial natriuretic peptide gene (NPPA), as well as genetically induced changes in circulating levels of NPs, have a pathogenic causal link with CV diseases and represent emerging markers of CV risk. Novel NP-based therapeutic strategies are currently under advanced clinical development, as they are expected to contribute to the future management of hypertension and HF. The present review provides a current appraisal of NPs' clinical implications and a critical perspective of the potential therapeutic impact of pharmacological manipulation of this class of CV hormones.

Natriuretic hormone: the ultimate determinant of the preservation of external sodium balance

The present manuscript focuses on a putative natriuretic hormone. It includes the history of a long-term search for the pure molecule, ranging from partial purification to synthesis. It includes a description of seven different bioassay systems used, a resume of the sequential steps in purification, and a summary of a series of experimental protocols employed in the effort to define the biologic properties of the inhibitor of sodium (Na) transport. Two closely related molecules were purified and synthesized. Both are xanthurenic acid derivatives (xanthurenic acid 8-O-β-D-glucoside and xanthurenic acid 8-O-sulfate). It is concluded that one or both of these two low molecular weight compounds (MW: 368 and 284) meet many of the criteria for the final modulator of Na excretion.

Effects of natriuretic peptides on electrical conduction in the sinoatrial node and atrial myocardium of the heart

Natriuretic peptides, including B-type and C-type natriuretic peptide (BNP and CNP), are powerful regulators of the cardiovascular system; however, their electrophysiological effects in the heart, particularly in the sinoatrial node (SAN), are incompletely understood. We have used high-resolution optical mapping to measure the effects of BNP and CNP, and the roles of natriuretic peptide receptors (NPR-A, NPR-B and NPR-C), on electrical conduction within the SAN and atrial myocardium. In basal conditions BNP and CNP (50-500 nm) increased conduction velocity (CV) within the SAN by ∼30% at the high dose and shifted the initial exit site superiorly. These effects sped conduction from the SAN to the surrounding atrial myocardium and were mediated by the NPR-A and NPR-B receptors. In the presence of isoproterenol (1 μm) the NPR-C receptor made a major contribution to the effects of BNP and CNP in the heart. In these conditions BNP, CNP and the NPR-C agonist cANF each decreased SAN CV and shifted the initial exit site inferiorly. The effects of cANF (30% reduction) were larger than BNP or CNP (∼15% reduction), indicating that BNP and CNP activate multiple natriuretic peptide receptors. In support of this, the inhibitory effects of BNP were absent in NPR-C knockout mice, where BNP instead elicited a further increase (∼25%) in CV. Measurements in externally paced atrial preparations demonstrate that the effects of natriuretic peptides on CV are partially independent of changes in cycle length. These data provide detailed novel insight into the complex effects of natriuretic peptides and their receptors on electrical conduction in the heart.

Novel vasodilators in heart failure

Heart failure is an important public health problem that is increasing in prevalence throughout the world. Not only is this condition common, but it is associated with significant morbidity and mortality as well as high costs to medical care systems. Vasodilator drugs help unload the heart and may have other effects that could benefit heart failure patients. Consequently, they have emerged as an important therapeutic approach for patients with this condition. Novel vasodilator therapies that are currently in development target new pathways, potentially giving clinicians alternate options for improving outcomes in this vulnerable population. This review focuses on investigational drugs that have the ability to dilate blood vessels amongst their therapeutic properties. These drugs include the natriuretic peptides that activate particulate guanylate cyclase, the novel agent cinaciguat that activates the soluble guanylate cyclase system, and finally a recombinant form of the naturally occurring vasodilating agent relaxin, a hormone that mediates many of the changes that allows the cardiovascular system to successfully adapt to pregnancy.

Caveolin and caveolae in age associated cardiovascular disease

It is estimated that the elderly (> 65 years of age) will increase from 13%−14% to 25% by 2035. If this trend continues, > 50% of the United States population and more than two billion people worldwide will be “aged” in the next 50 years. Aged individuals face formidable challenges to their health, as aging is associated with a myriad of diseases. Cardiovascular disease is the leading cause of morbidity and mortality in the United States with > 50% of mortality attributed to coronary artery disease and > 80% of these deaths occurring in those age 65 and older. Therefore, age is an important predictor of cardiovascular disease. The efficiency of youth is built upon cellular signaling scaffolds that provide tight and coordinated signaling. Lipid rafts are one such scaffold of which caveolae are a subset. In this review, we consider the importance of caveolae in common cardiovascular diseases of the aged and as potential therapeutic targets. We specifically address the role of caveolin in heart failure, myocardial ischemia, and pulmonary hypertension.

Evaluation of Short-Term Use of N-Acetylcysteine as a Strategy for Prevention of Anthracycline-Induced Cardiomyopathy: EPOCH Trial - A Prospective Randomized Study

Background and Objectives

We investigate to determine whether N-acetylcysteine (NAC) can prevent anthracycline-induced cardiotoxicity.

Subjects and Methods

A total of 103 patients were enrolled in this prospective randomized open label controlled trial. They are patients first diagnosed with breast cancer or lymphoma, who require chemotherapy, including anthracycline like adriamycine or epirubicine. Patients were randomized to the NAC group {n=50; 1200 mg orally every 8 hours starting before and ending after the intravenous infusion of anthracycline in all chemotherapy cycles (3-6)} or the control group (n=53). Primary outcome was the decrease in left ventricular ejection fraction (LVEF) absolutely ≥10% from the baseline and concomitantly <50% at 6-month. Composite of all-cause death, heart failure and readmission were compared.

Results

The primary outcome was not significantly different in the NAC and control groups {3/47 (6.4%) vs. 1/52 (1.9%), p=0.343}. The mean LVEF significantly decreased in both the NAC (from 64.5 to 60.8%, p=0.001) and control groups (from 64.1 to 61.3%, p<0.001) after the completion of whole chemotherapy. The mean LVEF change did not differ between the two groups (-3.64% in NAC vs. -2.78% in control group, p=0.502). Left ventricular (LV) end systolic dimension increased with higher trend in NAC by 3.08±4.56 mm as compared with 1.47±1.83 mm in the control group (p=0.064). LV end diastolic dimension did not change in each group and change does not differ in both. Peak E, A and E/A ratio change and cardiac enzymes were comparable in two groups. Cumulative 12-month event rate was 6% and 3.8% in the NAC group and the control group, respectively, with no difference (p=0.672).

Conclusion

We cannot prove that NAC prevents anthracycline-induced cardiomyopathy.

In-vivo evaluation of an in situ polymer precipitation delivery system for a novel natriuretic peptide

This study reports on the release of a novel natriuretic peptide, CD-NP, from an in situ polymer precipitation delivery system. Following extensive screening of in-vitro release profiles, an in-vivo evaluation of the efficacy of the delivery system was carried out in Wistar rats. Gel injection was performed subcutaneously on the back of the rats. A secondary messenger, cyclic Guanosine 3'5' Monophosphate (cGMP), was tested for verification of CD-NP bioactivity, in addition to direct measurements of CD-NP levels in plasma and urine using a radio-immuno assay. Plasma evaluation showed an elevated level of CD-NP over 3 weeks' duration. Unexpectedly, plasma cGMP level followed a decreasing trend over the same duration despite high CD-NP level. Loss of drug bioactivity was ruled out as a high level of CD-NP and cGMP excretion was observed in the treatment group as compared to baseline readings. This unexpected low-plasma cGMP levels and high-urinary cGMP excretion suggest that there might be other compensatory responses to regulation of the CDNP bioactivity as a result of the high drug dosing. The results stress the importance of assessing the overall bioactivity of released drug (in-vivo) concurrently in addition to measuring its concentrations, to determine the correct release profile.

Differential expression of the pro-natriuretic peptide convertases corin and furin in experimental heart failure and atrial fibrosis

In heart failure (HF), the cardiac hormone natriuretic peptides (NPs) atrial (ANP), B-type (BNP), and C-type (CNP) play a key role to protect cardiac remodeling. The proprotein convertases corin and furin process their respective pro-NPs into active NPs. Here we define in a canine model of HF furin and corin gene and protein expression in normal and failing left atrium (LA) or ventricle (LV) testing the hypothesis that the NP proproteins convertases production is altered in experimental HF. Experimental canine HF was produced by rapid right ventricular pacing for 10 days. NPs, furin, and corin mRNA expression were determined by quantitative RT-PCR. Protein concentration or expression was determined by immunostaining, radioimmunoassay, or Western blot. Furin and corin proteins were present in normal canine LA and LV myocardium and vasculature and in smooth muscle cells. In normal canines, expression of NPs was dominant in the atrium compared with the ventricle. In experimental early stage HF characterized with marked atrial fibrosis, ANP, BNP, and CNP mRNA, and protein concentrations were higher in HF LA but not HF LV compared with normals. In LA, corin mRNA and protein expressions in HF were lower, whereas furin mRNA and protein expressions were higher than normals. NPs and furin expressions were augmented in the atrium in experimental early stage HF and, conversely, corin mRNA and protein expressions were decreased with atrial remodeling. Selective changes of these NP convertases may have significance in the regulation of pro-NP processing and atrial remodeling in early stage HF.

Vascular effects and electrolyte homeostasis of the natriuretic peptide isolated from Crotalus oreganus abyssus (North American Grand Canyon rattlesnake) venom

Crotalus oreganus abyssus is a rattlesnake that is usually found in the Grand Canyon, United States of America. Knowledge regarding the composition of C. o. abyssus venom is scarce. New natriuretic peptides (NPs) have been isolated and characterized from the venoms of members of the Crotalinae family. The NP family comprises three members, ANP (atrial natriuretic peptide), BNP (b-type natriuretic peptide) and CNP (c-type natriuretic peptide), and has an important role in blood pressure regulation and electrolyte homeostasis. The aim of the present study was to characterize a novel natriuretic-like peptide (Coa_NP2), isolated from C. o. abyssus venom. The Coa_NP2 presents an average molecular mass of 3419.88Da (theoretical average molecular mass 3418.94Da, monoisotopic molecular mass 3416.66Da and theoretical PI 7.78) and its amino acid sequence presents the loop region that is characteristic of natriuretic peptides. The peptide has 32 amino acids and its complete sequence is SYGISSGCFGLKLDRIGTMSGLGCWRLLQDSP. Coa_NP2 is a natriuretic peptide of the ANP/BNP-like family, since the carboxyterminal region of CNP has its own NP domain. We demonstrate, herein, that Coa_NP2 produces a dose-dependent decrease in mean arterial pressure in rats, followed by significant increases in concentrations of markers of nitric oxide formation measured in the plasma and vasorelaxation in a thoracic aortic ring bath. The structural and biological aspects confirm Coa_NP2 as a new natriuretic peptide, isolated from snake venom.

Differences in hemodynamic responses between intravenous carperitide and nicorandil in patients with acute heart failure syndromes

While recent guidelines for the treatment of acute heart failure syndromes (AHFS) recommend pharmacotherapy with vasodilators in patients without excessively low blood pressure (BP), few reports have compared the relative efficiency of vasodilators on hemodynamics in AHFS patients. The present study aimed to assess the differences in hemodynamic responses between intravenous carperitide and nicorandil in patients with AHFS. Thirty-eight consecutive patients were assigned to receive 48-h continuous infusion of carperitide (n = 19; 0.0125-0.05 μg/kg/min) or nicorandil (n = 19; 0.05-0.2 mg/kg/h). Hemodynamic parameters were estimated at baseline, and 2, 24, and 48 h after drug administration using echocardiography. After 48 h of infusion, systolic BP was significantly more decreased in the carperitide group compared with that in the nicorandil group (22.1 ± 20.0 % vs 5.3 ± 10.4 %, P = 0.003). While both carperitide and nicorandil significantly improved hemodynamic parameters, improvement of estimated pulmonary capillary wedge pressure was greater in the carperitide group (38.2 ± 14.5 % vs 26.5 ± 18.3 %, P = 0.036), and improvement of estimated cardiac output was superior in the nicorandil group (52.1 ± 33.5 % vs 11.4 ± 36.9 %, P = 0.001). Urine output for 48 h was greater in the carperitide group, but not to a statistically significant degree (4203 ± 1542 vs 3627 ± 1074 ml, P = 0.189). Carperitide and nicorandil were differentially effective in improving hemodynamics in AHFS patients. This knowledge may enable physicians in emergency wards to treat and manage patients with AHFS more effectively and safely.

The natriuretic peptides BNP and CNP increase heart rate and electrical conduction by stimulating ionic currents in the sinoatrial node and atrial myocardium following activation of guanylyl cyclase-linked natriuretic peptide receptors

Natriuretic peptides (NPs) are best known for their ability to regulate blood vessel tone and kidney function whereas their electrophysiological effects on the heart are less clear. Here, we measured the effects of BNP and CNP on sinoatrial node (SAN) and atrial electrophysiology in isolated hearts as well as isolated SAN and right atrial myocytes from mice. BNP and CNP dose-dependently increased heart rate and conduction through the heart as indicated by reductions in R-R interval, P wave duration and P-R interval on ECGs. In conjunction with these ECG changes BNP and CNP (100 nM) increased spontaneous action potential frequency in isolated SAN myocytes by increasing L-type Ca(2+) current (I(Ca,L)) and the hyperpolarization-activated current (I(f)). BNP had no effect on right atrial myocyte APs in basal conditions; however, in the presence of isoproterenol (10nM), BNP increased atrial AP duration and I(Ca,L). Quantitative gene expression and immunocytochemistry data show that all three NP receptors (NPR-A, NPR-B and NPR-C) are expressed in the SAN and atrium. The effects of BNP and CNP on SAN and right atrial myocytes were maintained in mutant mice lacking functional NPR-C receptors and blocked by the NPR-A antagonist A71915 indicating that BNP and CNP function through their guanylyl cyclase-linked receptors. Our data also show that the effects of BNP and CNP are completely absent in the presence of the phosphodiesterase 3 inhibitor milrinone. Based on these data we conclude that NPs can increase heart rate and electrical conduction by activating the guanylyl cyclase-linked NPR-A and NPR-B receptors and inhibiting PDE3 activity.

Characterization of a long-acting recombinant human serum albumin-atrial natriuretic factor (ANF) expressed in Pichia pastoris

The cardiac hormone atrial natriuretic factor (ANF) combines pharmacological properties of drugs used to treat essential hypertension (EH), congestive heart failure (CHF) and acute myocardial infarction (AMI). Treatment of CHF or AMI patients with an intravenous (iv) infusion of the circulating form of ANF (ANF(99-126)) produces significant clinical improvement. The short half-life (5 min) and peptide nature of ANF impose logistic restrictions for chronic administration. To increase its half-life, we fused ANF and human serum albumin (HSA) mini-genes by recombination in Pichia pastoris. The activity of three configurations of the fusion protein was tested in vitro and in vivo. The fusion protein that comprised of C-terminus HSA connected to N-terminus ANF via a hexaglycine linker showed the best outcome; it increased cGMP production in vitro. In vivo an iv bolus of HSA-ANF into mice increased significantly plasma cGMP levels and lowered blood pressure (BP) for up to 6 h hence successfully extended ANF half-life in plasma while retaining its biological activity. HSA-ANF represents the basis for development in the chronic therapeutic use of ANF.

Influence of sex and hormone status on circulating natriuretic peptides

OBJECTIVES

The aim of this study was to assess the relationship between sex hormones and natriuretic peptide levels in community-based adults.

BACKGROUND

Women have higher circulating natriuretic peptide concentrations than men, but the mechanisms for these sex-related differences and the impact of hormone therapy are unclear. Experimental studies suggest that androgens may suppress natriuretic peptide secretion.

METHODS

We measured N-terminal pro-B-type natriuretic peptide (NT-proBNP), total testosterone, and sex hormone-binding globulin plasma levels in 4,056 men and women (mean age 40 ± 9 years) from the Framingham Heart Study Third-Generation cohort. Sex/hormone status was grouped as: 1) men; 2) post-menopausal women not receiving hormone replacement therapy; 3) pre-menopausal women not receiving hormonal contraceptives; 4) post-menopausal women receiving hormone replacement therapy; and 5) pre-menopausal women receiving hormonal contraceptives.

RESULTS

Circulating NT-proBNP levels were associated with sex/hormone status (overall p < 0.0001). Men had lower NT-proBNP levels than women of all menopause or hormone groups, and women receiving hormonal contraceptives had higher NT-proBNP levels than women who were not receiving hormone therapy (all p < 0.0001). These relationships remained significant after adjusting for age, body mass index, and cardiovascular risk factors. Across sex/hormone status groups, free testosterone (FT) levels decreased and sex hormone-binding globulin levels increased in tandem with increasing NT-proBNP levels. In sex-specific analyses, NT-proBNP levels decreased across increasing quartiles of FT in men (p for trend <0.01) and women (p for trend <0.0001). Adjustment for FT markedly attenuated the association between sex/hormone status and NT-proBNP concentrations.

CONCLUSIONS

These findings suggest that lower levels of circulating androgens and the potentiating effect of exogenous female hormone therapy contribute to the higher circulating NT-proBNP concentrations in women.

The utility of cardiac biomarkers, tissue velocity and strain imaging, and cardiac magnetic resonance imaging in predicting early left ventricular dysfunction in patients with human epidermal growth factor receptor II-positive breast cancer treated with adjuvant trastuzumab therapy

OBJECTIVES

The aim of this study was to evaluate whether cardiac biomarkers, tissue velocity (TVI) and strain imaging, and cardiac magnetic resonance imaging can predict early left ventricular (LV) dysfunction in human epidermal growth factor receptor II-positive breast cancer patients treated with trastuzumab in the adjuvant setting.

BACKGROUND

Early indexes of LV systolic dysfunction with noninvasive cardiac imaging would be useful for addressing the cardiac safety profile of trastuzumab, potentially avoiding the detrimental effects of heart failure.

METHODS

We used cardiac biomarkers, TVI and strain imaging, and cardiac magnetic resonance imaging to detect pre-clinical changes in LV systolic function, before conventional changes in left ventricular ejection fraction (LVEF) in human epidermal growth factor receptor II-positive breast cancer patients treated with trastuzumab in the adjuvant setting.

RESULTS

Of 42 patients (mean age 47 ± 9 years) prospectively followed between 2007 and 2009, 10 (25%) developed trastuzumab-mediated cardiomyopathy (CM). Troponin T, C-reactive protein, and brain natriuretic peptide did not change over time. Within 3 months of adjuvant therapy with trastuzumab, there was a significant difference in the lateral S' between the normal cohort and the CM group (9.1 ± 1.6 cm/s and 6.4 ± 0.6 cm/s, respectively, p < 0.05). Similarly, the peak global longitudinal and radial strain decreased as early as 3 months in the trastuzumab-mediated cardiotoxicity group. As compared with both global longitudinal and radial strain, only S' was able to identify all 10 patients who developed trastuzumab-mediated CM. The LVEF subsequently decreased at 6 months of follow-up in all 10 patients, necessitating discontinuation of the drug. All 10 patients demonstrated delayed enhancement of the lateral wall of the LV within the mid-myocardial portion, consistent with trastuzumab-induced CM.

CONCLUSIONS

Both TVI and strain imaging were able to detect pre-clinical changes in LV systolic function, before conventional changes in LVEF, in patients receiving trastuzumab in the adjuvant setting.

Cardiac-specific overexpression of caveolin-3 attenuates cardiac hypertrophy and increases natriuretic peptide expression and signaling

OBJECTIVES

We hypothesized that cardiac myocyte-specific overexpression of caveolin-3 (Cav-3), a muscle-specific caveolin, would alter natriuretic peptide signaling and attenuate cardiac hypertrophy.

BACKGROUND

Natriuretic peptides modulate cardiac hypertrophy and are potential therapeutic options for patients with heart failure. Caveolae, microdomains in the plasma membrane that contain caveolin proteins and natriuretic peptide receptors, have been implicated in cardiac hypertrophy and natriuretic peptide localization.

METHODS

We generated transgenic mice with cardiac myocyte-specific overexpression of caveolin-3 (Cav-3 OE) and also used an adenoviral construct to increase Cav-3 in cardiac myocytes.

RESULTS

The Cav-3 OE mice subjected to transverse aortic constriction had increased survival, reduced cardiac hypertrophy, and maintenance of cardiac function compared with control mice. In left ventricle at baseline, messenger ribonucleic acid for atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) were increased 7- and 3-fold, respectively, in Cav-3 OE mice compared with control subjects and were accompanied by increased protein expression for ANP and BNP. In addition, ventricles from Cav-3 OE mice had greater cyclic guanosine monophosphate levels, less nuclear factor of activated T-cell nuclear translocation, and more nuclear Akt phosphorylation than ventricles from control subjects. Cardiac myocytes incubated with Cav-3 adenovirus showed increased expression of Cav-3, ANP, and Akt phosphorylation. Incubation with methyl-β-cyclodextrin, which disrupts caveolae, or with wortmannin, a PI3K inhibitor, blocked the increase in ANP expression.

CONCLUSIONS

These results imply that cardiac myocyte-specific Cav-3 OE is a novel strategy to enhance natriuretic peptide expression, attenuate hypertrophy, and possibly exploit the therapeutic benefits of natriuretic peptides in cardiac hypertrophy and heart failure.

Thirty years of research on atrial natriuretic factor: historical background and emerging concepts

The discovery of the natriuretic properties of atrial muscle extracts pointed to the existence of an endocrine function of the heart that is now known to be mediated by the polypeptide hormones atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP). On the basis of such a finding, approximately 27 000 publications to date have described a wide variety of biological properties of the heart hormones as well as their application as therapeutic agents and biomarkers of cardiac disease. Stimulation of secretion of ANF and BNP from the atria is mediated through mechanisms involving G proteins of the G(q) or G(o) types. We showed that the latter type underlies the transduction of muscle stretch into stimulated secretion and that it is more highly abundant in atria than in ventricles. The Gα(o)()-1 subunit appears to play a key role in the biogenesis of atrial granules and in the intracellular targeting of their contents. Protein interaction studies using a yeast two-hybrid approach showed interactions between Gα(o)()-1, proANF, and the intermediate conductance, calcium-activated K(+) channel SK4. Pharmacological inhibition of this channel decreases ANF secretion. Unpublished studies using in vitro knockdowns suggest interdependency in granule protein expression levels. These studies suggest previously unknown mechanisms of intracellular targeting and secretion control of the heart hormones that may find an application in the therapeutic manipulation of circulating ANF and BNP.

Intramyocardial BNP gene delivery improves cardiac function through distinct context-dependent mechanisms

BACKGROUND

B-type natriuretic peptide (BNP) is an endogenous peptide produced under physiological and pathological conditions mainly by ventricular myocytes. It has natriuretic, diuretic, blood pressure-lowering, and antifibrotic actions that could mediate cardiorenal protection in cardiovascular diseases. In the present study, we used BNP gene transfer to examine functional and structural effects of BNP on left ventricular (LV) remodeling.

METHODS AND RESULTS

Human BNP was overexpressed by using adenovirus-mediated gene delivery in normal rat hearts and in hearts during the remodeling process after infarction and in an experimental model of angiotensin II-mediated hypertension. In healthy hearts, BNP gene delivery into the anterior wall of the LV decreased myocardial fibrosis (P<0.01, n=7 to 8) and increased capillary density (P<0.05, n=7 to 8) associated with a 7.3-fold increase in LV BNP peptide levels. Overexpression of BNP improved LV fractional shortening by 22% (P<0.05, n=6 to 7) and ejection fraction by 19% (P<0.05, n=6 to 7) after infarction. The favorable effect of BNP gene delivery on cardiac function after infarction was associated with normalization of cardiac sarcoplasmic reticulum Ca(2+)-ATPase expression and phospholamban Thr17-phosphorylation. BNP gene delivery also improved fractional shortening and ejection fraction in angiotensin II-mediated hypertension as well as decreased myocardial fibrosis and LV collagen III mRNA levels but had no effect on angiogenesis or Ca(2+)-ATPase expression and phospholamban phosphorylation.

CONCLUSIONS

Local intramyocardial BNP gene delivery improves cardiac function and attenuates adverse postinfarction and angiotensin II-induced remodeling. These results also indicate that myocardial BNP has pleiotropic, context-dependent, favorable actions on cardiac function and suggest that BNP acts locally as a key mechanical load-activated regulator of angiogenesis and fibrosis.

657WTAPELL663 motif of the photoreceptor ROS-GC1: a general phototransduction switch

This study documents the identity of an intriguing transduction mechanism of the [Ca(2+)](i) signals by the photoreceptor ROS-GC1. Despite their distal residences and operational modes in phototransduction, the two GCAPs transmit and activate ROS-GC1 through a common Ca(2+) transmitter switch (Ca(2+)TS). A combination of immunoprecipitation, fluorescent spectroscopy, mutational analyses and reconstitution studies has been used to demonstrate that the structure of this switch is (657)WTAPELL(663). The two Ca(2+) signaling GCAP pathways converge in Ca(2+)TS, get transduced, activate ROS-GC1, generate the LIGHT signal second messenger cyclic GMP and yet functionally perform divergent operations of the phototransduction machinery. The findings define a new Ca(2+)-modulated photoreceptor ROS-GC transduction model; it is depicted and discussed for its application to processing the different shades of LIGHT.

Decompensated heart failure is associated with reduced corin levels and decreased cleavage of pro-atrial natriuretic peptide

BACKGROUND

By promoting salt and water excretion, the corin and the atrial natriuretic peptide (ANP) system should help to maintain fluid balance in heart failure. Yet, the development of fluid retention despite high levels of ANP-related peptides suggests that this compensatory system is limited.

METHODS AND RESULTS

Levels of circulating corin (the pro-ANP-converting enzyme) and pro-ANP were measured in hospitalized patients with heart failure, using novel immunoassays. Patients (n=14) had severe heart failure (New York Heart Association class III-IV) with a median ejection fraction of 18% and median brain natriuretic peptide levels of 1940 pg/mL. In heart failure, median plasma corin levels were 7.6-fold lower than measured in plasma from 16 normal control subjects (180 versus 1368 pg/mL, P<0.01). In contrast, in patients with heart failure, levels of plasma N-terminal ANP peptides (N-ANP and pro-ANP) levels were markedly elevated (42.0 versus 7.5 ng/mL, P<0.01). Levels of uncleaved pro-ANP, measured by novel immunoassays, were significantly higher in patients with heart failure (P<0.01), suggesting that corin cleavage of pro-ANP was impaired. Median plasma levels of cyclic guanosine monophosphate were elevated in patients with heart failure (150.0 versus 7.6 pmol/mL, P<0.01), and plasma cyclic guanosine monophosphate levels positively correlated with the fractional amount of cleaved pro-ANP (r(s)=0.59, P<0.03) but not with levels of uncleaved pro-ANP, implying that the cellular response to ANP remained intact.

CONCLUSIONS

Taken together, these data suggest that there may be patients for whom low corin levels and impaired pro-ANP cleavage contribute to acute decompensation.

Mechanisms of atrial structural changes caused by stretch occurring before and during early atrial fibrillation

Structural remodelling occurring before, due to the underlying heart disease, and during atrial fibrillation (AF) sets the stage for permanent AF. Current therapy in AF aims to maintain sinus rhythm in symptomatic patients, but outcome is unfortunately poor. Stretch of the atria is a main contributor to atrial remodelling. In this review, we describe different aspects of structural remodelling as seen in animal models and in patients with AF, including atrial enlargement, cellular hypertrophy, dedifferentiation, fibrosis, apoptosis, and loss of contractile elements. In the second part, we describe downstream signals of mechanical stretch and their contribution to AF and structural remodelling. Ultimately, knowledge of mechanisms underlying structural remodelling may help to identify new pharmacological targets for AF prevention.

Feedback control through cGMP-dependent protein kinase contributes to differential regulation and compartmentation of cGMP in rat cardiac myocytes

RATIONALE

We have shown recently that particulate (pGC) and soluble guanylyl (sGC) cyclases synthesize cGMP in different compartments in adult rat ventricular myocytes (ARVMs).

OBJECTIVE

We hypothesized that cGMP-dependent protein kinase (PKG) exerts a feedback control on cGMP concentration contributing to its intracellular compartmentation.

METHODS AND RESULTS

Global cGMP levels, cGMP-phosphodiesterase (PDE) and pGC enzymatic activities were determined in purified ARVMs. Subsarcolemmal cGMP signals were monitored in single cells by recording the cGMP-gated current (I(CNG)) in myocytes expressing the wild-type rat olfactory cyclic nucleotide-gated (CNG) channel. Whereas the NO donor S-nitroso-N-acetyl-penicillamine (SNAP) (100 μmol/L) produced little effect on I(CNG), the response increased 2-fold in the presence of the PKG inhibitors KT5823 (50 nmol/L) or DT-2 (2 μmol/L). The effect of KT5823 was abolished in the presence of the nonselective cyclic nucleotide PDE inhibitor 3-isobutyl-1-methylxantine (IBMX) (100 μmol/L) or the selective cGMP-PDE5 inhibitor sildenafil (100 nmol/L). PKG inhibition also potentiated the effect of SNAP on global cGMP levels and fully blocked the increase in cGMP-PDE5 activity. In contrast, PKG inhibition decreased by ≈50% the I(CNG) response to ANP (10 and 100 nmol/L), even in the presence of IBMX. Conversely, PKG activation increased the I(CNG) response to ANP and amplified the stimulatory effect of ANP on pGC activity.

CONCLUSIONS

PKG activation in adult cardiomyocytes limits the accumulation of cGMP induced by NO donors via PDE5 stimulation but increases that induced by natriuretic peptides. These findings support the paradigm that cGMP is not uniformly distributed in the cytosol and identifies PKG as a key component in this process.

VAMP-1, VAMP-2, and syntaxin-4 regulate ANP release from cardiac myocytes

ANP is a peptide released by cardiac myocytes that regulates blood pressure and natriuresis. However, the molecular mechanisms controlling ANP release from cardiac myocytes are not defined. We now identify three components of the exocytic machinery that regulate ANP release from atrial myocytes. We found that cardiac myocytes express N-ethylmaleimide sensitive factor (NSF), soluble NSF attachment protein (α-SNAP), and SNAP receptors (SNAREs). Additionally we found that specific SNARE molecules, VAMP-1 and VAMP-2, both co-sediment and co-localize with ANP. Also, one SNARE molecule, syntaxin-4, partially co-sediments and partially co-localizes with ANP. Furthermore, these three SNAREs, syntaxin-4 and VAMP-1 and VAMP-2, form a SNARE complex inside cardiac myocytes. Finally, knockdown of VAMP-1, VAMP-2, or syntaxin-4 blocks regulated release of ANP. In contrast, silencing of VAMP-3 did not have an effect on ANP release. Our data suggest that three specific SNAREs regulate cardiac myocyte exocytosis of ANP. Pathways that modify the exocytic machinery may influence natriuresis and blood pressure.

Proatrial natriuretic peptide is a better predictor of 28-day mortality in septic shock patients than proendothelin-1

BACKGROUND

Septic shock is a major health care problem that affects a heterogeneous population of patients. To improve sepsis management, a key point is to decrease this heterogeneity by stratifying patients according to specific criteria, such as appropriate biomarkers. As the early phase of septic shock is characterized by cardiovascular dysfunction, precursors of vasoactive hormones represent interesting candidates. The objective of the present study was to concomitantly assess the predictive value of C-terminal proendothelin-1 and midregional proatrial natriuretic peptide (CT-proET-1 and MR-proANP, respectively vasoconstrictor and vasodilator) on 28-day mortality following septic shock.

METHODS

In this observational study which included 99 patients, concentrations of MR-proANP and CT-proET-1 were measured using an immunoluminometric assay three times within the first week after the onset of septic shock.

RESULTS

While MR-proANP concentrations were significantly increased in non-survivors in comparison with survivors, no differences were noted for CT-proET-1. Increased MR-proANP concentrations were significantly associated with mortality after both univariate and multivariate analyses, adjusted for usual clinical confounders [SAPS II (simplified acute physiology score II), SOFA (sepsis-related organ failure assessment) scores and number of co-morbidities].

CONCLUSIONS

In septic shock patients, MR-proANP appears to be a good predictor of 28-day mortality, whereas CT-proET-1 does not present any predictive value during monitoring.

Role of juxtamembrane and transmembrane domains in the mechanism of natriuretic peptide receptor A activation

Natriuretic peptide receptor A (NPRA) is a noncovalent homodimeric receptor, composed of an extracellular domain (ECD) with a ligand-binding site, a single transmembrane domain (TM), and an intracellular domain (ICD) exhibiting guanylyl cyclase activity. NPRA activation by atrial natriuretic peptide (ANP) leads to cGMP production, which plays important roles in cardiovascular homeostasis. Initial studies have shown that activation of NPRA involves a conformational change in the juxtamembrane domain (JM). However, crystallographic study of the soluble ECD of NPRA has failed to document JM structure, and the conformational change involved in transmembrane signal transduction is still unknown. To analyze this conformational change, we first sequentially substituted nine amino acids of the JM with a cysteine residue. By studying the mutant's capacity to form ANP-induced or constitutive covalent disulfide dimers, we evaluated the relative proximity of JM residues, before and after NPRA activation. These results obtained with the full-length receptor demonstrate a high proximity of specific JM residues and are in disagreement with crystallography data. We also tested the hypothesis that signal transduction involves a TM rotation mechanism leading to ICD activation. By introducing one to five alanine residues into the TM alpha-helix, we show that a TM rotation of 40 degrees leads to constitutive NPRA activation. We finally studied the role of the TM in NPRA dimerization. By using the ToxR system, we demonstrate that the last JM residues are required to stabilize the TM dimer. Using these experimental data, we generated a new molecular model illustrating the active conformation of NPRA, where the JM and TM are depicted.

The cutting edge: membrane-anchored serine protease activities in the pericellular microenvironment

The serine proteases of the trypsin-like (S1) family play critical roles in many key biological processes including digestion, blood coagulation, and immunity. Members of this family contain N- or C-terminal domains that serve to tether the serine protease catalytic domain directly to the plasma membrane. These membrane-anchored serine proteases are proving to be key components of the cell machinery for activation of precursor molecules in the pericellular microenvironment, playing vital functions in the maintenance of homoeostasis. Substrates activated by membrane-anchored serine proteases include peptide hormones, growth and differentiation factors, receptors, enzymes, adhesion molecules and viral coat proteins. In addition, new insights into our understanding of the physiological functions of these proteases and their involvement in human pathology have come from animal models and patient studies. The present review discusses emerging evidence for the diversity of this fascinating group of membrane serine proteases as potent modifiers of the pericellular microenvironment through proteolytic processing of diverse substrates. We also discuss the functional consequences of the activities of these proteases on mammalian physiology and disease.

Ventricular-arterial uncoupling in heart failure with preserved ejection fraction after myocardial infarction in dogs - invasive versus echocardiographic evaluation

Background

Heart failure with preserved left ventricular ejection fraction and abnormal diastolic function is commonly observed after recovery from an acute myocardial infarction. The aim of this study was to investigate the physiopathology of heart failure with preserved ejection fraction in a model of healed myocardial infarction in dogs.

Methods

Echocardiography, levels of neurohormones and conductance catheter measurements of left ventricular pressure-volume relationships were obtained in 17 beagle dogs 2 months after a coronary artery ligation, and in 6 controls.

Results

Healed myocardial infarction was associated with preserved echocardiographic left ventricular ejection fraction (0.57 ± 0.01, mean ± SEM) and altered Doppler mitral indices of diastolic function. NT-proBNP was increased, aldosterone was decreased, and norepinephrine was unchanged. Invasive measurements showed a markedly decreased end-systolic elastance (2.1 ± 0.2 vs 6.1 ± 0.8, mmHg/ml, p < 0.001) and end-systolic elastance to effective arterial elastance ratio (0.6 ± 0.1 vs 1.4 ± 0.2, p < 0.001), with altered active relaxation (dP/dtmin -1992 ± 71 vs -2821 ± 305, mmHg/s, p < 0.01) but preserved left ventricular capacitance (70 ± 6 vs 61 ± 3, ml at 20 mmHg, p = NS) and stiffness constant. Among echocardiographic variables, the wall motion score index was the most reliable indicator of cardiac contractility while E', E/A and E'/A' were correlated to dP/dtmin.

Conclusions

In the canine model of healed myocardial infarction induced by coronary ligation, heart failure is essentially characterized by an altered contractility with left ventricular-arterial uncoupling despite vascular compensation rather than by abnormal diastolic function

Induction of apoptosis by plant natriuretic peptides in rat cardiomyoblasts

Atrial natriuretic peptide (ANP) has an important role in maintaining the homeostasis of body fluids and blood pressure and also in preventing cardiac hypertrophy and initiating the process of apoptosis. An immunoreactive analog of ANP was discovered in plants over a decade ago and termed plant natriuretic peptide (PNP). PNP is a small protein that contains sequence and structural similarity to ANP within a predicted protruding psi (psi) loop. Since application of ANP or PNP stimulates similar functional effects in plants, it is conceivable that PNP may have effects on mammalian cells. In this report, we show that purified recombinant PNP induces apoptosis in a dose dependent and cell type specific manner. Rat cardiac myoblasts (H9c2 cells) were more susceptible to the apoptotic promoting effects of PNP and ANP than HEK-293T cells where PNP had a protective effect at lower concentrations. Similarly rat thoracic myoblasts (A-10) were less responsive to both PNP and ANP than the H9c2 cells. Since PNP is mimicking the effect of ANP in this instance, PNP may prove to be a useful lead molecule for developing novel therapeutic natriuretic peptides.

Systolic blood pressure at admission as a predictor of the response to initial carperitide therapy in patients hospitalized for acute decompensated heart failure with left ventricular systolic dysfunction

PURPOSE

In patients with acute decompensated heart failure (ADHF) and left ventricular systolic dysfunction (LVSD), the role of initial vasodilator therapy remains uncertain. The present study aimed to evaluate the acute efficacy of initial carperitide therapy and to predict its response in ADHF patients with LVSD.

METHODS

Twenty-four consecutive patients with ADHF and LVSD were enrolled. Inclusion criteria were a left ventricular ejection fraction < 40%, systolic blood pressure (BP) > 90 mm Hg, and pulmonary capillary wedge pressure >or=18 mm Hg at baseline. Hemodynamic parameters were evaluated by right heart catheterization before and after carperitide infusion. Responders were defined as a >or=30% reduction of pulmonary capillary wedge pressure (PCWP) or a decrease to < 16 mm Hg within 6 h after carperitide infusion.

RESULTS

Seventeen (71%) of the 24 patients were responders for initial carperitide therapy. The responders had significantly higher systolic BP and cardiac index at baseline compared with nonresponders. The area under the curve (AUC) for systolic BP was 0.93 and a cut-off value of 120 mm Hg had a sensitivity of 94% and specificity of 86% for predicting the efficacy of carperitide. The AUC for the cardiac index was 0.88 and a cut-off value of 2.30 L/min/m(2) had a sensitivity of 65% and a specificity of 100% for predicting the response to carperitide.

CONCLUSIONS

The initial use of carperitide therapy safely reduces PCWP in ADHF patients with LVSD and baseline systolic BP may be useful for predicting the response to initial carperitide therapy for ADHF with LVSD.

The role of nesiritide in heart failure

BACKGROUND

Heart failure afflicts > 5 million patients in the US, with about 550,000 new diagnoses a year. Side effects and increased mortality limit heart failure treatment. Nesiritide is the newest addition to therapeutic options for treatment of acute decompensated heart failure (ADHF). It has been used as single in-patient infusions, multiple out-patient infusions, and perioperatively to improve hemodynamics and promote diuresis. Initially well-received, meta-analyses suggesting increased mortality and renal dysfunction after nesiritide use were published 4 - 5 years after its introduction in the US. These reports prompted new recommendations on nesiritide use by an expert panel.

OBJECTIVE

Critical review of the studies leading to approval of nesiritide and the current recommendations for its use.

METHODS

Medline search and Pubmed search using nesiritide or natrecor for text word searches.

CONCLUSION

Nesiritide represents the first drug in a new class designed for treatment of ADHF. In patients with ADHF, nesiritide improves hemodynamic parameters and reduces dyspnea. Questions remain about possible increased mortality and side effects. A continuing study expected to enroll 7000 patients by 2010 has been designed to clarify whether nesiritide reduces mortality, hospital length-of-stay and renal parameters in patients with ADHF.

Role of guanylate cyclase modulators in decompensated heart failure

In this review we investigate the role of particulate and soluble guanylate cyclase (pGC and sGC, respectively) pathways in heart failure, and several novel drugs that modify guanylate cyclase. Nesiritide and ularitide/urodilatin are natriuretic peptides with vasodilating, natriuretic and diuretic effects, acting on pGC, whilst cinaciguat (BAY 58-2667) is a novel sGC activator. Cinaciguat has a promising and novel mode of action because it can stimulate cyclic guanosine-3',5'-monophosphate synthesis by targeting sGC in its nitric oxide-insensitive, oxidised ferric (Fe(3+)) or haem-free state. Thus, cinaciguat may also be effective under oxidative stress conditions resulting in oxidised or haem-free sGC refractory to traditional organic nitrate therapies. Preliminary studies of cinaciguat in patients with acute decompensated heart failure show substantial improvements in haemodynamics and symptoms, whilst maintaining renal function.

B-type natriuretic peptide as predictor of heart failure in patients with acute ST elevation myocardial infarction, single-vessel disease, and complete revascularization: follow-up study

AIM

To assess the concentration of B-type natriuretic peptide (BNP) as a predictor of heart failure in patients with acute ST elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention (PCI) with successful and complete revascularization.

METHODS

Out of a total of 220 patients with acute STEMI admitted to the Sisters of Mercy University Hospital in the period January 1 to December 31, 2007, only patients with acute STEMI undergoing primary PCI who had single vessel disease and were successfully revascularized were included in the study. Selected patients had no history of myocardial infarction or heart failure and a normal or near-normal left ventricular ejection fraction (> or =50%) assessed by left ventriculography at admission. Only 58 patients met the inclusion criteria for the study. Out of those, 6 patients refused to participate in the study, and another 5 could not be followed up, so a total of 47 patients were evaluated. Blood samples were taken for measurement of BNP levels at admission, 24 hours later, and 7 days later. Patients were followed up for 1 year. The primary outcome was reduction in left ventricular ejection fraction (LVEF) to <50% after 1 year.

RESULTS

Patients who developed echocardiographic signs of reduced systolic function defined as LVEF<50% had significantly higher values of BNP (> or =80 pg/mL) at 24 hours (P=0.001) and 7 days (P=0.020) after STEMI and successful reperfusion. Patients who had BNP levels > or =80 pg/mL after 7 days were 21 times more likely to develop LVEF<50 (odds ratio, 20.8; 95% confidence interval, 2.2-195.2; P=0.008).

CONCLUSION

BNP can be used as a predictor of reduced systolic function in patients with STEMI who underwent successful reperfusion and had normal ejection fraction at admission.