Recombinant human brain natriuretic peptide attenuates ischemic brain injury in mice by inhibiting oxidative stress and cell apoptosis via activation of PI3K/AKT/Nrf2/HO-1 pathway.

Ischemic stroke followed by cerebral artery occlusion is a main cause of chronic disability worldwide. Recombinant human brain natriuretic peptide (rhBNP) has been reported to alleviate sepsis-induced cognitive dysfunction and brain I/R injury. However, the function and molecular mechanisms of rhBNP in ischemic brain injury have not been clarified. For establishment of an animal model of ischemic brain injury, C57BL/6 mice were treated with middle cerebral artery occlusion (MCAO) surgery for 1 h and reperfusion for 24 h. After subcutaneous injection of rhBNP into model mice, neurologic deficits were assessed by evaluating behavior of mice according to Longa scoring system, and TTC staining was utilized to determine the brain infarct size of mice. The levels of oxidative stress markers, superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and malondialdehyde (MDA), were detected in hippocampal tissues of mice by corresponding kits. Cell apoptosis in hippocampus tissues was examined by TUNEL staining. Protein levels of antioxidant enzymes (HO-1 and NQO1) in cerebral cortex, apoptotic markers (Bax, Bcl-2, and cleaved caspase), and PI3K/AKT pathway-associated factors in hippocampus were tested by western blot analysis. The results revealed that injection of rhBNP decreased neurologic deficit scores, the percent of brain water content, and infarct volume. Additionally, rhBNP downregulated MDA level, upregulated the levels of SOD, CAT, and GSH in hippocampus of mice, and increased protein levels of HO-1 and NQO1 in the cortex. Cell apoptosis in hippocampus tissues of model mice was inhibited by rhBNP which was shown as the reduced TUNEL-positive cells, the decreased Bax, cleaved caspase-3, and cleaved caspase-9 protein levels, and the enhanced Bcl-2 protein level. In addition, rhBNP treatment activated the PI3K/AKT signaling pathway and upregulated the protein levels of HO-1 and NRF2. Overall, rhBNP activates the PI3K/AKT/HO-1/NRF2 pathway to attenuate ischemic brain injury in mice after MCAO by suppression of cell apoptosis and oxidative stress.

Novel enhancers of guanylyl cyclase-A activity acting via allosteric modulation.

BACKGROUND AND PURPOSE: Guanylyl cyclase-A (GC-A), activated by endogenous atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), plays an important role in the regulation of cardiovascular and renal homeostasis and is an attractive drug target. Even though small molecule modulators allow oral administration and longer half-life, drug targeting of GC-A has so far been limited to peptides. Thus, in this study we aimed to develop small molecular activators of GC-A. EXPERIMENTAL APPROACH: Hits were identified through high-throughput screening and optimized by in silico design. Cyclic GMP was measured in QBIHEK293A cells expressing GC-A, GC-B or chimerae of the two receptors using AlphaScreen technology. Binding assays were performed in membrane preparations or whole cells using 125 I-ANP. Vasorelaxation was measured in aortic rings isolated from Wistar rats. KEY RESULTS: We have identified small molecular allosteric enhancers of GC-A, which enhanced ANP or BNP effects in cellular systems and ANP-induced vasorelaxation in rat aortic rings. The mechanism of action appears novel and not mediated through previously described allosteric binding sites. In addition, the selectivity and activity depend on a single amino acid residue that differs between the two similar receptors GC-A and GC-B. CONCLUSION AND IMPLICATIONS: We describe a novel allosteric binding site on GC-A, which can be targeted by small molecules to enhance ANP and BNP effects. These compounds will be valuable tools in further development and proof-of-concept of GC-A enhancement for the potential use in cardiovascular therapy.

Natriuretic peptides potentiate cardiac hypertrophic response to noradrenaline in rats.

Excessive activation of the sympathetic nervous system is involved in cardiovascular damage including cardiac hypertrophy. Natriuretic peptides are assumed to exert protective actions for the heart, alleviating hypertrophy and/or fibrosis of the myocardium. In contrast to this assumption, we show in the present study that both atrial and C-type natriuretic peptides (ANP and CNP) potentiate cardiac hypertrophic response to noradrenaline (NA) in rats. Nine-week-old male Wistar rats were continuously infused with subcutaneous 30 micro-g/h NA without or with persistent intravenous administration of either 1.0 micro-g/h ANP or CNP for 14 days. Blood pressure (BP) was recorded under an unrestrained condition by a radiotelemetry system. Cardiac hypertrophic response to NA was evaluated by heart weight/body weight (HW/BW) ratio and microscopic measurement of myocyte size of the left ventricle. Mean BP levels at the light and dark cycles rose by about 20 mmHg following NA infusion for 14 days, with slight increases in HW/BW ratio and ventricular myocyte size. Infusions of ANP and CNP had no significant effects on mean BP in NA-infused rats, while two natriuretic peptides potentiated cardiac hypertrophic response to NA. Cardiac hypertrophy induced by co-administration of NA and ANP was attenuated by treatment with prazosin or atenolol. In summary, both ANP and CNP potentiated cardiac hypertrophic effect of continuously infused NA in rats, suggesting a possible pro-hypertrophic action of natriuretic peptides on the heart.

[Clinical observation of Qiliqiangxin capsule combined with recombinant human brain natriuretic peptide in patients with acute heart failure].

Objective: To observe the clinical effect of Qiliqiangxin capsule combined with recombinant human brain natriuretic peptide in acute left heart failure patients 7 days after onset as well as the effects of plasma MDA and ET-1. Methods: In total, 240 hospitalized patients with acute left heart failure from October 2017 to May 2021 were selected from the Department of Emergency and Critical Care Center of Beijing Anzhen Hospital, Capital Medical University and the Department of Cardiology of the Jilin Provincial People's Hospital. They were randomly divided into routine treatment group and combined treatment group, with 120 cases in each group. The routine treatment group was treated with vasodilation, diuresis, cardiotonic and recombinant human brain natriuretic peptide. The combined treatment group was treated with Qiliqiangxin capsules based on the routine treatment group. One week later, the changes in clinical efficacy, ejection fraction, left ventricular commoid diameter, and plasma BNP, MDA, and ET-1 were compared between the two groups before and after treatment. SPSS 11.5 statistical software was used. The measurement data was expressed in x¯±s, the independent sample t-test was used for comparison between groups, and the paired t-test was used for comparison before and after treatment within groups. Counting data was expressed as case (%), and the rank sum test was used for inter-group comparison. Result: In terms of clinical efficacy, the total effective rate of the combined treatment group was significantly higher than that of the conventional treatment group, and the difference was statistically significant (P<0.05). Compared with the routine treatment group, the left ventricular ejection fraction in the combined treatment group was significantly increased (P<0.05). The levels of plasma BNP, MDA and ET-1 were significantly decreased (P<0.05). Conclusion: Qiliqiangxin capsule combined with rhBNP treatment can effectively improve the clinical symptoms of acute heart failure, as well as reduce the lipid peroxidation product MDA content and endothetin ET-1 level in blood. The clinical application value of the Qiliqiangxin capsule needs to be further confirmed by further trials.

Relaxin-3 Ameliorates Diabetic Cardiomyopathy by Inhibiting Endoplasmic Reticulum Stress.

Background: This study is aimed at investigating whether relaxin-3 exhibits protective effects against cardiomyopathy in diabetic rats by suppressing ERS. Methods: Eighty male SD rats were randomly divided into two groups: controls (n = 20) and diabetes (n = 60). The streptozotocin-treated rats were randomly divided into three groups: diabetic group (DM), low-dose relaxin-3 group (0.2 µg/kg/d), and high-dose relaxin-3 group (2 µg/kg/d). The myocardial tissues and collagen fiber were observed by hematoxylin and eosin (H&E) and Masson staining. Serum brain natriuretic peptide (BNP), troponin (TNI), myoglobin, interleukin (IL-17), interleukin (IL)-1α, and tumor necrosis factor (TNF)-α were determined by ELISA. The protein expression of glucose regulatory protein 78 (GRP78) and C/EBP homologous protein (CHOP) in the heart tissue of each group was detected by Western blot analysis. Results: (1) HE and Masson staining indicated that relaxin-3 could attenuate myocardial lesions and myocardial collagen volume fraction. (2) BNP, TnI, and myoglobin in the DM group at four and eight weeks were significantly higher than in the controls (P < 0.01). The relaxin-3-treated groups showed significantly reduced serum BNP, TnI, and myoglobin levels compared with the DM group (P < 0.05). (3) IL-17, IL-1α, and TNF-α levels in the DM rats at 4 weeks were higher than in the controls (P < 0.05). Low or high dose of relaxin-3-treated groups showed reduced serum IL-17 and TNF-α levels compared with the DM group at four and eight weeks (P < 0.05). (4) CHOP and GRP78 protein expression was increased in the DM group at four and eight weeks compared with the controls (P < 0.01), and small and large doses of relaxin-3 significantly reduced GRP78 and CHOP protein expression. Conclusions: Exogenous relaxin-3 ameliorates diabetic cardiomyopathy by inhibiting ERS in diabetic rats.

Kallikrein-related peptidase-8 (KLK8) aggravated hypoxia-induced right ventricular hypertrophy by targeting P38 MAPK/P53 signaling pathway.

Right ventricular (RV) hypertrophy and further heart failure are major co-morbidities, resulting in the premature death of patients with hypoxic pulmonary hypertension (HPH). The regulatory effects of kallikrein-related peptidase (KLK) family members on cardiac function have been extensively studied. However, to the best of the authors' knowledge, the regulatory effects of KLK8 on RV hypertrophy caused by HPH have yet to be reported. The aim of the present study was to assess KLK8 expression in the RV tissue of HPH-modeled rats, and to further explore the effects and underlying mechanism of KLK8 in regulating the hypertrophy of hypoxia-induced H9c2 cardiomyocytes. In HPH model rats, increases in the right ventricle hypertrophy index, the right ventricular systolic pressure, cardiac output, as well as pulmonary artery wall thickness were observed. Western blot analysis revealed that KLK8 expression and MAPK/p53 signaling activity were enhanced in the RVs of rats in an RV HPH rat model. In hypoxia-induced H9c2 cardiomyocytes, KLK8 overexpression promoted cardiomyocyte hypertrophy, whereas KLK8 silencing showed the opposite results. KLK8 overexpression increased the expression levels of ventricular hypertrophy markers, including atrial natriuretic peptide, brain natriuretic peptide and myosin heavy chain 7, which were blocked upon addition of the p38 MAPK inhibitor, SB202190. Conversely, KLK8 silencing caused a decrease in the expression levels of the ventricular hypertrophy markers, which were further reduced via inhibition of the p38 MAPK/p53 signaling pathway. Taken together, the results of the present study have shown that KLK8 may subtly regulate RV hypertrophy, and therefore KLK8 may be a promising therapeutic target for treating HPH-induced RV hypertrophy.

Natriuretic Peptides Regulate Prostate Cells Inflammatory Behavior: Potential Novel Anticancer Agents for Prostate Cancer.

Inflammation, by inducing a tumor-promoting microenvironment, is a hallmark for prostate cancer (PCa) progression. NOD-like receptor protein 3 (NLRP3)-inflammasome activation, interleukin-1ß (IL-1ß) secretion, and cancer cell-released extracellular vesicles (EVs) contribute to the establishment of tumor microenvironment. We have shown that PC3-derived EVs (PC3-EVs) activate inflammasome cascade in non-cancerous PNT2 cells. It is known that the endogenous biomolecules and Natriuretic Peptides (NPs), such as ANP and BNP, inhibit inflammasome activation in immune cells. Here we investigated whether ANP and BNP modify PCa inflammatory phenotype in vitro. By using PNT2, LNCaP, and PC3 cell lines, which model different PCa progression stages, we analyzed inflammasome activation and the related pathways by Western blot and IL-1ß secretion by ELISA. We found that tumor progression is characterized by constitutive inflammasome activation, increased IL-1ß secretion, and reduced endogenous NPs expression. The administration of exogenous ANP and BNP, via p38-MAPK or ERK1/2-MAPK, by inducing NLRP3 phosphorylation, counteract inflammasome activation and IL-1ß maturation in PC3 and PC3-EVs-treated PNT2 cells, respectively. Our results demonstrate that NPs, by interfering with cell-specific signaling pathways, exert pleiotropic anti-inflammatory effects converging toward inflammasome phosphorylation and suggest that NPs can be included in a drug repurposing process for PCa.

Increasing heart vascularisation after myocardial infarction using brain natriuretic peptide stimulation of endothelial and WT1+ epicardial cells.

Brain natriuretic peptide (BNP) treatment increases heart function and decreases heart dilation after myocardial infarction (MI). Here, we investigated whether part of the cardioprotective effect of BNP in infarcted hearts related to improved neovascularisation. Infarcted mice were treated with saline or BNP for 10 days. BNP treatment increased vascularisation and the number of endothelial cells in all areas of infarcted hearts. Endothelial cell lineage tracing showed that BNP directly stimulated the proliferation of resident endothelial cells via NPR-A binding and p38 MAP kinase activation. BNP also stimulated the proliferation of WT1+ epicardium-derived cells but only in the hypoxic area of infarcted hearts. Our results demonstrated that these immature cells have a natural capacity to differentiate into endothelial cells in infarcted hearts. BNP treatment increased their proliferation but not their differentiation capacity. We identified new roles for BNP that hold potential for new therapeutic strategies to improve recovery and clinical outcome after MI.

Recombinant Human Brain Natriuretic Peptide Attenuates Myocardial Ischemia-Reperfusion Injury by Inhibiting CD4+ T Cell Proliferation via PI3K/AKT/mTOR Pathway Activation.

Inflammation plays a major role in the development of myocardial ischemia-reperfusion (IR) injury. Recombinant human brain natriuretic peptide (rhBNP), a man-made version of a peptide that is elevated in heart failure, exhibits anti-inflammatory effects in various tissues. However, its role in myocardial IR injury remains unclear. In this study, we demonstrate that treatment with rhBNP provided protection for mice against myocardial IR injury as manifested by reduced infarct size and well-preserved myocardial, attenuated inflammatory infiltration and CD4+ T cell proliferation function, and inhibited expression of proinflammatory related genes. Furthermore, mechanistic studies revealed that rhBNP inhibited Jurkat T proliferation by promoting PI3K/AKT/mTOR phosphorylation. Collectively, our data suggest that the administration of rhBNP during IR injury could expand our understanding of the cardioprotective effects of rhBNP.

The value of brain natriuretic peptide in the prosthetic valve thrombosis.

: We aimed to investigate how prosthetic valve thrombosis (PVT) affects brain natriuretic peptide (BNP) levels and how BNP changes following thrombolytic therapy. The study included 70 consecutive patients with left-sided mechanical PVT who received thrombolytic therapy. The patients were divided into two groups, namely obstructive thrombus (n = 42) and nonobstructive thrombus (NOT, n = 28). BNP levels of patients were assessed before and after thrombolytic therapy. BNP levels were higher in obstructive thrombus group than NOT group in whole study population, in patients with mitral PVT and in patients with aortic PVT [325.0 (189.5-496.0) vs. 84.0 (44.5-140.0), P < 0.001, 323.0 (193-449.0) vs. 59.0 (37.0-131.0), P < 0.001 and 321.0 (132.0-525.0) vs. 99.0 (60.5-173.0), P < 0.001]. BNP levels were positively correlated with transmitral and transaortic mean gradients, and negatively correlated with mitral valve area (r: 0.374, P = 0.013; r: 0.432, P = 0.035 and; r: -0.642, P < 0.001, respectively). BNP values above 165 pg/ml may predict the presence of obstructive thrombus with a sensitivity of 88.0%, and a specificity of 79.0% (AUC = 0.928, 95% confidence interval: 0.871-0.986, P < 0.001). Following thrombolytic therapy, BNP levels (pg/ml) significantly decreased from 325.0 (189.5-496.0) to 137.0 (101.7-224.5), P < 0.001, in all patients with obstructive thrombus, from 323.0 (193.0-449.0) to 129.0 (98.0-223.0), P < 0.001, in patients with only mitral obstructive thrombus and from 321.0 (132.0-525.0) to 181.0 (99.0-217.5), P < 0.001, in patients with only aortic obstructive thrombus. BNP levels are significantly higher in prosthetic valve patients with obstructive thrombus than in those with NOT and decrease in patients with obstructive thrombus after thrombolytic therapy. A cut off value of BNP of at least 165.0 pg/ml was found to discriminate obstructive thrombus from NOT.

The Protective Effect of rhBNP on Postresuscitation Myocardial Dysfunction in a Rat Cardiac Arrest Model.

PURPOSE: We investigated the protective effects and the underlying mechanisms through which recombinant human brain natriuretic peptide (rhBNP) acts on postresuscitation myocardial dysfunction (PRMD) in the cardiac arrest (CA) model. METHODS: Ventricular fibrillation was induced and untreated for 6 min. And the time of cardiopulmonary resuscitation was 8 min, after which defibrillation was attempted in this rat model. 24 Sprague Dawley rats (450-550g) were randomized into cardiopulmonary resuscitation (CPR) + rhBNP and CPR + placebo groups after restoration of spontaneous circulation (ROSC). rhBNP was infused at PR 30 min (loading dose: 1.5 µg/kg, 3 min; maintenance dose: 0.01 µg/kg, 3 min; maintenance dose: 0.01 α (TNF-α (TNF-α (TNF-κB (NF-κB (NF. RESULTS: The administration of rhBNP attenuated the severity of PRMD and myocardial tissue injuries, with improvement of MAP (mean arterial blood pressure), ETCO2 (end-tidal CO2), serum level of NT-proBNP, EF, CO, and MPI values. The serum levels and protein expression levels in myocardial tissue of IL-6 and TNF-α (TNF-κB (NF. CONCLUSION: Our research demonstrated that the administration of rhBNP attenuated the severity of PRMD and myocardial tissue injuries and increased the 24 h survival rate in this CA model. rhBNP administration also reduced the serum and myocardial tissue levels of IL-6 and TNF-α after ROSC, likely due to the suppression of the TLR4/NF-κB signaling pathway and the regulation of inflammatory mediator secretion.α (TNF-κB (NF.

The therapeutic effect of B-type natriuretic peptides in acute decompensated heart failure.

B-type natriuretic peptide (BNP) exhibits roles in natriuresis and diuresis, making it an ideal drug that may aid in diuresing a fluid-overloaded patient with poor or worsening renal function. Several randomized clinical trials have tested the hypothesis that infusions of pharmacological doses of BNP to acute heart failure (HF) patients may enhance decongestion and preserve renal function in this clinical setting. Unfortunately, none of these have demonstrated beneficial outcomes. The current challenge for BNP research in acute HF lies in addressing a failure of concept and a reluctance to abandon an ineffective research model. Future success will necessitate a detailed understanding of the mechanism of action of BNP, as well as better integration of basic and clinical science.

Cardiovascular Pleiotropic Effects of Natriuretic Peptides.

Atrial natriuretic peptide (ANP) is a cardiac hormone belonging to the family of natriuretic peptides (NPs). ANP exerts diuretic, natriuretic, and vasodilatory effects that contribute to maintain water-salt balance and regulate blood pressure. Besides these systemic properties, ANP displays important pleiotropic effects in the heart and in the vascular system that are independent of blood pressure regulation. These functions occur through autocrine and paracrine mechanisms. Previous works examining the cardiac phenotype of loss-of-function mouse models of ANP signaling showed that both mice with gene deletion of ANP or its receptor natriuretic peptide receptor A (NPR-A) developed cardiac hypertrophy and dysfunction in response to pressure overload and chronic ischemic remodeling. Conversely, ANP administration has been shown to improve cardiac function in response to remodeling and reduces ischemia-reperfusion (I/R) injury. ANP also acts as a pro-angiogenetic, anti-inflammatory, and anti-atherosclerotic factor in the vascular system. Pleiotropic effects regarding brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP) were also reported. In this review, we discuss the current evidence underlying the pleiotropic effects of NPs, underlying their importance in cardiovascular homeostasis.

Longitudinal relationship between B-type natriuretic peptide and anxiety in coronary heart disease patients with depression.

OBJECTIVE: Patients with coronary heart disease (CHD) suffer from physical limitations, but also from psychological distress. Natriuretic peptides may be involved in the neurobiological processes that modulate psychological adaptation, as they are increased in heart disease and seem to have an anxiolytic-like function. Longitudinal data on this association are scarce. METHODS: To assess the relationship between NT-proBNP and anxiety (Hospital Anxiety and Depression Scale (HADS)), we used secondary data from a multicenter trial from baseline to 24 months. Patients (N = 308, 80.8% male, mean age 60.1 years) had stable CHD and moderate levels of depression (HADS ≥8). RESULTS: Multiple linear regression adjusted for age, sex, BMI, and physical functioning revealed NT-proBNP as a significant predictor for anxiety at baseline, 1, 6, 12, 18, and 24 months (all p < .05). Linear mixed model analysis with the six anxiety measures as level-1 variable and NT-proBNP as fixed factor revealed a significant time*NT-proBNP interaction (t(1535.99) = -2.669, p = .01) as well as a significant time*NT-proBNP*sex interaction (t(1535.99) = 3.277, p = .001), when NT-proBNP was dichotomized into lowest vs. the three highest quartiles. CONCLUSION: Our results indicate a stable negative association of baseline NT-proBNP with anxiety over two years. In men and women, different pathways modulating this relationship appear to be in effect. Female patients with very low NT-proBNP levels, despite their cardiac disease, show persistently higher levels of anxiety compared to women with higher levels of NT-proBNP and compared to men. Trial name: A Stepwise Psychotherapy Intervention for Reducing Risk in Coronary Artery Disease (SPIRR-CAD). TRIAL REGISTRATION: www.clinicaltrials.govNCT00705965; www.isrctn.com ISRCTN76240576.

Chronic B-Type Natriuretic Peptide Therapy Prevents Atrial Electrical Remodeling in a Rabbit Model of Atrial Fibrillation.

BACKGROUND: Atrial fibrillation (AF) is an important and growing clinical problem. Current pharmacological treatments are unsatisfactory. Electrical remodeling has been identified as one of the principal pathophysiological mechanisms that promote AF, but there are no effective therapies to prevent or correct electrical remodeling in patients with AF. In AF, cardiac production and circulating levels of B-type natriuretic peptide (BNP) are increased. However, its functional significance in AF remains to be determined. We assessed the hypotheses that chronic BNP treatment may prevent the altered electrophysiology in AF, and preventing AF-induced activation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) may play a role. METHODS AND RESULTS: Forty-four rabbits were randomly divided into sham, rapid atrial pacing (RAP at 600 beats/min for 3 weeks), RAP/BNP, and sham/BNP groups. Rabbits in the RAP/BNP and sham/BNP groups received subcutaneous BNP (20 µg/kg twice daily) during the 3-week study period. HL-1 cells were subjected to rapid field stimulation for 24 hours in the presence or absence of BNP, KN-93 (a CaMKII inhibitor), or KN-92 (a nonactive analog of KN-93). We compared atrial electrical remodeling-related alterations in the ion channel/function/expression of these animals. We found that only in the RAP group, AF inducibility was significantly increased, atrial effective refractory periods and action potential duration were reduced, and the density of ICa, L and Ito decreased, while IK1 increased. The changes in the expressions of Cav1.2, Kv4.3, and Kir2.1 and currents showed a similar trend. In addition, in the RAP group, the activation of CaMKIIδ and phosphorylation of ryanodine receptor 2 and phospholamban significantly increased. Importantly, these changes were prevented in the RAP/BNP group, which were further validated by in vitro studies. CONCLUSIONS: Chronic BNP therapy prevents atrial electrical remodeling in AF. Inhibition of CaMKII activation plays an important role to its anti-AF efficacy in this model.

A mouse model of heart failure exhibiting pulmonary edema and pleural effusion: Useful for testing new drugs.

INTRODUCTION: Mouse models of chronic heart failure (HF) have been widely used in HF research. However, the current HF models most often use the C57BL/6 mouse strain and do not show the clinically relevant characteristics of pulmonary congestion. In this study, we developed a robust mouse model of HF in the BALB/c mouse strain, exhibiting pulmonary edema and pleural effusion, and we validated the model using the standard pharmacological therapies in patients with chronic HF and reduced ejection fraction (HFrEF) or acute decompensated HF. METHODS: After induction of myocardial infarction (MI) by permanent ligation of the left coronary artery in BALB/c mice, the cardiac function, pulmonary congestion, disease biomarkers, and survival were evaluated using the angiotensin converting enzyme inhibitor enalapril or the loop diuretic furosemide. Enalapril was administered 4 weeks post-MI for 6 weeks or furosemide was given 10 weeks post-MI for 4 days, when pulmonary congestion was evident. RESULTS: Compared to sham controls, MI mice developed systolic dysfunction, exhibited lung weight increase at 4 weeks, and progressively developed pleural effusion (60% of the animals) at 10 weeks. Compared to the vehicle, enalapril significantly reduced the lung weight and pleural effusion, preserved systolic function, and improved survival. Furthermore, furosemide completely abolished the pleural effusion. Enalapril or furosemide also reduced the plasma brain natriuretic peptide concentration. DISCUSSION: The post-MI HF in BALB/c mice shows reproducible and robust pulmonary congestion and may be a clinically relevant model for novel drug testing for treatment in patients with HFrEF or acute decompensated HF.

High doses of ANP and BNP exacerbate lipolysis in humans and the lipolytic effect of BNP is associated with cardiac triglyceride content in pigs.

Drugs facilitating the cardioprotective effects of natriuretic peptides are introduced in heart failure treatment. ANP and BNP also stimulate lipolysis and increase circulating concentrations of free fatty acids (FFAs); an aspect, however, thought to be confined to primates. We examined the lipolytic effect of natriuretic peptide infusion in healthy young men and evaluated the effect in a porcine model of myocardial ischemia and reperfusion. Six young healthy normotensive men underwent infusion with ANP, BNP, or CNP for 20 min. Blood samples were collected before, during, and after infusion for measurement of FFAs. In a porcine model of myocardial ischemia and reperfusion, animals were infused for 3 h with either BNP (n = 7) or saline (n = 5). Blood samples were collected throughout the infusion period, and cardiac tissue was obtained after infusion for lipid analysis. In humans, ANP infusion dose-dependently increased the FFA concentration in plasma 2.5-10-fold (baseline vs. 0.05 µg/kg/min P < 0.002) and with BNP 1.6-3.5-fold (P = 0.001, baseline vs. 0.02 µg/kg/min) 30 min after initiation of infusion. Infusion of CNP did not affect plasma FFA. In pigs, BNP infusion induced a 3.5-fold increase in plasma FFA (P < 0.0001), which remained elevated throughout the infusion period. Triglyceride content in porcine right cardiac ventricle tissue increased ∼5.5 fold in animals infused with BNP (P = 0.02). Natriuretic peptide infusion has similar lipolytic activity in human and pig. Our data suggest that short-term infusion increases the cardiac lipid content, and that the pig is a suitable model for studies of long-term effects mediated by natriuretic peptides.

Effects of cardiac resynchronization therapy on right ventricular function during rest and exercise, as assessed by radionuclide angiography, and on NT-proBNP levels.

AIM: We carried out this study to investigate mid-term effects of cardiac resynchronization therapy (CRT) on right ventricular (RV) function and neurohormonal response, expressed by N-terminal pro-brain natriuretic peptide (NT-proBNP), in heart failure patients stratified by baseline RV ejection fraction (RVEF). METHODS AND RESULTS: Thirty-six patients with nonischemic dilated cardiomyopathy underwent technetium-99m radionuclide angiography with bicycle exercise immediately after CRT implantation (during spontaneous rhythm and after CRT activation) and 3 months later. Plasma NT proBNP was assessed before implantation and after 3 months. At baseline, RVEF was impaired (≤35%) in 14 patients, preserved (>35%) in 22. At 3 months, RVEF improved during rest and exercise (P = .02) in patients with impaired RV function, while remaining unchanged in patients with preserved RV function. Rest and exercise RV dyssynchrony decreased in both groups at follow-up (P < .05). A similar mid-term improvement in left ventricular (LV) function and NT-proBNP was observed in patients with impaired and preserved RVEF. In the former, the decrease in NT-proBNP correlated with the improvements both in LV and RV dyssynchrony and functions. CONCLUSION: CRT may improve RV performance, during rest and exercise, and neurohormonal response in heart failure patients with nonischemic dilated cardiomyopathy and baseline RV dysfunction. RV dysfunction should not be considered per se a primary criterion for excluding candidacy to CRT.

B-type natriuretic peptide attenuates endoplasmic reticulum stress in H9c2 cardiomyocytes underwent hypoxia/reoxygenation injury under high glucose/high fat conditions.

Exogenously administered B-type natriuretic peptide (BNP) has been shown to provide cardioprotection against various heart diseases. However, the underlying mechanisms remain elusive. This study explores whether BNP exerts its cardioprotection against hypoxia/reoxygenation (H/R) injury under high glucose/high fat (HG/HF) conditions in cardiac H9c2 cells and uncovers the underlying mechanisms. Our data revealed that BNP significantly increased the cell viability and decreased the release of lactate dehydrogenase (LDH) and creatine kinase (CK), with a maximal effect at the BNP concentration of 10-7 mol/L. In addition, by analyzing the activation of cleaved caspase-3 and by Annexin V-FITC/PI staining, we showed that BNP attenuated H/R-induced cell apoptosis in HG/HF conditions. Western blot analysis showed enhanced phosphorylation of protein kinase RNA (PKR)-like endoplastmic reticulum (ER) kinase (PERK) and eukaryotic initiation factor 2α (eIF2α)(one of the three main signaling pathways in endoplastmic reticulum (ER) stress), and increased expression of GRP78 and CHOP proteins (ER stress-related proteins) in H9c2 cells which underwent H/R in HG/HF conditions. Treatment with BNP or 8-Br-cGMP (an analog of cGMP) reversed this activation. However, this effect was significantly weakened by KT-5823, a selective cGMP-dependent protein kinase G (PKG) inhibitor. In addition, similar to BNP, treatment with a specific inhibitor of ER stress tauroursodeoxycholic acid (TUDCA) protected the cells against H/R injury exposed to HG/HF conditions. In conclusion, these findings demonstrated that BNP effectively protected cells against H/R injury under HG/HF conditions by inhibiting the ER stress via activation of the cGMP-PKG signaling pathway.

The Endogenous Lusitropic and Chronotropic Agent, B-Type Natriuretic Peptide, Limits Cardiac Troponin Release in Cancer Patients with an Early Impairment of Myocardial Relaxation Induced by Anthracyclines.

We have reported that cancer patients treated with anthracycline-based or nonanthracycline chemotherapy developed an early impairment of myocardial relaxation at echocardiography or persistent elevations of the cardiac hormone B-type natriuretic peptide (BNP). Post-hoc pharmacologic analyses showed that BNP elevations were induced by impaired relaxation and caused positive lusitropic effects that maintained normal relaxation. High BNP levels and impaired relaxation were therefore characterized as mutually exclusive manifestations of diastolic dysfunction, but high BNP levels resulted in positive chronotropism and inappropriate tachycardia. Some patients developed increased circulating levels of cardiac troponin I isoform (cTnI), a marker of cardiomyocyte necrosis. Here we have characterized whether cTnI elevations correlated with diastolic dysfunction that manifested as impaired relaxation or a high level of BNP. The effects of high BNP levels on cTnI elevations were also characterized. We show that impaired relaxation or high BNP levels were significantly more frequent in patients with cTnI elevations. High BNP levels diminished the plasma peak and area under the curve of cTnI, but this result was accompanied by inappropriate tachycardia. cTnI elevations occurred only in patients treated with anthracyclines; moreover, the association of impaired relaxation or high BNP levels with cTnI elevations was significantly more frequent in doxorubicin-treated patients compared with patients treated with its analog, epirubicin. These findings describe cause-and-effect relations between impaired relaxation and cardiomyocyte necrosis, illuminate the role of anthracycline analogs, denote that the beneficial effects of BNP in relieving impaired relaxation and cardiomyocyte necrosis are counterbalanced by inappropriate tachycardia. Patients showing troponin elevations and impaired relaxation or high BNP levels should be treated with lusitropic drugs that lack a positive chronotropism.