Atrial Natriuretic Peptide Research Articles

Cross talk on therapeutic strategies: natriuretic peptides and inhibiting neprilysin in hypertension management.

Hypertension, a prevalent cardiovascular condition globally, remains a significant public health concern due to its association with increased cardiovascular morbidity and mortality. Despite the availability of various antihypertensive therapies, achieving optimal blood pressure control in patients remains a challenge. Valsartan/sacubitril (ARNi), marketed as Entresto by Novartis, combines valsartan, an angiotensin receptor blocker, with sacubitril, an inhibitor of neprilysin. Neprilysin is responsible for breaking down natriuretic peptides and other vasoactive substances. Inhibiting neprilysin prevents the degradation of natriuretic peptides, enhancing their beneficial effects on blood pressure regulation. Natriuretic Peptides, including atrial natriuretic peptide (ANP) and brain natriuretic peptides (BNP), play pivotal roles in regulating blood pressure and cardiovascular homeostasis by promoting vasodilation, natriuresis, and antagonizing the renin-angiotensin-aldosterone system. Therefore, this combo drug lessens sensitivity to natriuretic peptides and tackles the processes in hypertension that activate the renin-angiotensin-aldosterone system. This review provides an overview of how natriuretic peptides (NPs) contribute to blood pressure regulation for the treatment of hypertension through inhibiting neprilysin. It highlights the ARNi's dual action that works synergistically by blocking the harmful effects of angiotensin II on blood vessels while simultaneously increasing the levels of beneficial natriuretic peptides. Schematic representation of the mechanism of action of ARNi. Abbreviation: -Renin angiotensin aldosterone system (RAAS), Natriuretic peptides (NP), Atrial Natriuretic peptide (ANP), Brain natriuretic peptide (BNP), C-type natriuretic peptide (CNP), Angiotensin II (Ang II), Angiotensin receptor neprilysin inhibitor (ARNI).

Architecture and activation of single-pass transmembrane receptor guanylyl cyclase.

The heart, in addition to its primary role in blood circulation, functions as an endocrine organ by producing cardiac hormone natriuretic peptides. These hormones regulate blood pressure through the single-pass transmembrane receptor guanylyl cyclase A (GC-A), also known as natriuretic peptide receptor 1. The binding of the peptide hormones to the extracellular domain of the receptor activates the intracellular guanylyl cyclase domain of the receptor to produce the second messenger cyclic guanosine monophosphate. Despite their importance, the detailed architecture and domain interactions within full-length GC-A remain elusive. Here we present cryo-electron microscopy structures, functional analyses and molecular dynamics simulations of full-length human GC-A, in both the absence and the presence of atrial natriuretic peptide. The data reveal the architecture of full-length GC-A, highlighting the spatial arrangement of its various functional domains. This insight is crucial for understanding how different parts of the receptor interact and coordinate during activation. The study elucidates the molecular basis of how extracellular signals are transduced across the membrane to activate the intracellular guanylyl cyclase domain.

Real-time imaging of cGMP signaling shows pronounced differences between glomerular endothelial cells and podocytes.

Recent clinical trials of drugs enhancing cyclic guanosine monophosphate (cGMP) signaling for cardiovascular diseases have renewed interest in cGMP biology within the kidney. However, the role of cGMP signaling in glomerular endothelial cells (GECs) and podocytes remains largely unexplored. Using acute kidney slices from mice expressing the FRET-based cGMP biosensor cGi500 in endothelial cells or podocytes enabled real-time visualization of cGMP. Stimulation with atrial natriuretic peptide (ANP) or SNAP (NO donor) and various phosphodiesterase (PDE) inhibitors elevated intracellular cGMP in both cell types. GECs showed a transient cGMP response upon particulate or soluble guanylyl cyclase activation, while the cGMP response in podocytes reached a plateau following ANP administration. Co-stimulation (ANP + SNAP) led to an additive response in GECs. The administration of PDE inhibitors revealed a broader basal PDE activity in GECs dominated by PDE2a. In podocytes, basal PDE activity was mainly restricted to PDE3 and PDE5 activity. Our data demonstrate the existence of both guanylyl cyclase pathways in GECs and podocytes with cell-specific differences in cGMP synthesis and degradation, potentially suggesting new therapeutic options for kidney diseases.

Safety, tolerability and blood pressure lowering of the innovative guanylyl cyclase a-receptor activator MANP in an ethnically diverse resistant hypertension population: a phase 1B clinical trial

Abstract Background/Introduction MANP is a novel atrial natriuretic peptide (ANP) analog bioengineered as a particulate guanylyl cyclase A receptor (GC-A) activator with superior receptor binding, resistance to neprilysin degradation, natriuretic, aldosterone suppressing and blood pressure (BP) lowering properties than native ANP. MANP is now under clinical development for resistant hypertension (RH). The rationale for its design was the fundamental role of the ANP/GC-A system in BP homeostasis through which GC-A activation with MANP leads to BP reduction through renal, vascular, and hormonal mechanisms mediated by the second messenger cGMP. Purpose We investigated the safety, tolerability, cGMP activation and BP reductions of MANP compared to placebo in subjects with RH. Methods We performed a double-blind, placebo controlled randomized trial in 36 RH patients comprised of approximately 50% non-African Americans (NAA) and 50% AA. MANP was administered in 6 cohorts receiving ascending subcutaneous (SQ) doses of MANP once daily from 3 ug/kg to a maximal dose of 7 ug/kg or placebo for 5 days and then followed for 21 days after dosing. Endpoints included safety, cGMP activation and changes in systolic BP (SBP), aldosterone (Aldo) levels and glomerular filtration rate (GFR). Results MANP was safe and well tolerated. One patient in the 7 ug/kg cohort was discontinued due to symptomatic hypotension. Compared to baseline, plasma cGMP increased in all MANP groups on Day 1 and Day 5 with no change in the placebo group. The maximal SBP reduction in the MANP group on Days 1 (D1) and 5 (D5) was -17.5 (D1) and -16 mmHg (D5) with 3 ug/kg (lowest dose) and -39.5 (D1) and -36.3 mmHg (D5) with 7 ug/kg (highest dose); Changes in the Placebo group were -6.3 (D1) and -16.7 mmHg (D5). Notably, the SBP reductions in AA were greater than NAA in the 4 and 7 ug/kg cohorts. After the 1-hour timepoint on both the first and fifth days, Aldo and percentage of Aldo reduction generally remained suppressed compared to baseline. Twenty-one days after MANP dosing, SBP remained lower in three groups receiving SQ MANP (4, 4.5 and 7 ug/kg) compared to placebo in association with a preservation of GFR. There were no reported drug related serious adverse events. Conclusions This clinical trial demonstrates that once a day SQ administration of MANP in RH subjects activates cGMP, without attenuation over 5 days, and reduces SBP and preserves GFR. At higher doses of MANP, SBP reductions were greater in AA compared to NAA. MANP also demonstrated Aldo inhibiting actions compared to placebo. Importantly, MANP was overall safe and well-tolerated. Our findings support the continued clinical development of MANP as a novel GC-A activating peptide for the treatment of RH.

A Cardiac-Targeting and Anchoring Bimetallic Cluster Nanozyme Alleviates Chemotherapy-Induced Cardiac Ferroptosis and PANoptosis.

Doxorubicin (DOX), a potent antineoplastic agent, is commonly associated with cardiotoxicity, necessitating the development of strategies to reduce its adverse effects on cardiac function. Previous research has demonstrated a strong correlation between DOX-induced cardiotoxicity and the activation of oxidative stress pathways. This work introduces a novel antioxidant therapeutic approach, utilizing libraries of tannic acid and N-acetyl-L-cysteine-protected bimetallic cluster nanozymes. Through extensive screening for antioxidative enzyme-like activity, an optimal bimetallic nanozyme (AuRu) is identified that possess remarkable antioxidant characteristics, mimicking catalase-like enzymes. Theoretical calculations reveal the surface interactions of the prepared nanozymes that simulate the hydrogen peroxide decomposition process, showing that these bimetallic nanozymes readily undergo OH⁻ adsorption and O₂ desorption. To enhance cardiac targeting, the atrial natriuretic peptide is conjugated to the AuRu nanozyme. These cardiac-targeted bimetallic cluster nanozymes, with their anchoring capability, effectively reduce DOX-induced cardiomyocyte ferroptosis and PANoptosis without compromising tumor treatment efficacy. Thus, the therapeutic approach demonstrates significant reductions in chemotherapy-induced cardiac cell death and improvements in cardiac function, accompanied by exceptional in vivo biocompatibility and stability. This study presents a promising avenue for preventing chemotherapy-induced cardiotoxicity, offering potential clinical benefits for cancer patients.

Cardiac corin and atrial natriuretic peptide regulate liver glycogen metabolism and glucose homeostasis

BackgroundCardiovascular function and metabolic homeostasis are closely linked, but the underlying mechanisms are not fully understood. Corin is a protease that activates atrial natriuretic peptide (ANP), an essential hormone for normal blood pressure and cardiac function. The goal of this study is to investigate a potential corin and ANP function in regulating liver glycogen metabolism and glucose homeostasis.MethodsLiver glycogen and blood glucose levels were analyzed in Corin or Nppa (encoding ANP) knockout (KO) mice. ANP signaling was examined in livers from Corin and Nppa KO mice and in cultured human and mouse hepatocytes by western blotting.ResultsWe found that Corin and Nppa KO mice had reduced liver glycogen contents and increased blood glucose levels. By analyzing conditional KO mice lacking either cardiac or renal Corin, we showed that cardiac corin and ANP act in an endocrine manner to enhance cGMP-protein kinase G (PKG)-AKT-GSK3 signaling in hepatocytes. In cultured hepatocytes, ANP treatment stimulated PKG signaling, glucose uptake, and glycogen production, which could be blocked by small molecule PKG and AKT inhibitors.ConclusionsOur results indicate that corin and ANP are important regulators in liver glycogen metabolism and glucose homeostasis, suggesting that defects in the corin and ANP pathway may contribute to both cardiovascular and metabolic diseases.

The influence of the daily salt-intake on the antihypertensive action and atrial natriuretic peptide level in patietns with angiotensin receptor neprilysin inhibition

Abstract Background The angiotensin receptor–neprilysin inhibitor (ARNI) is a drug which acts through angiotensin receptor blocking effect and the increase in atrail natriuretic peptide (ANP) through neprilysin inhibitor in hypertension (HT). These combined effects result in a reduced risk of hospitalization for heart failure or death from cardiovascular causes. ANP is also known for its various cardioprotective effects including vasodilator and natriuretic action. Acording to Guyton's pressure-natriuresis curve, the efficacy of angiotensin receptor blocker drugs is diminished in HT cases with high daily salt inatke. However, whether the effect of ARNI on HT is attenuated in patients with high daily salt intake remains unclear. Purpose The present study investigated the influence of a daily salt intake on the antihypertensive action and ANP level in patients with ARNI. Methods Fourty-four consecutive essential HT patients on ARNI were enrolled. Blood pressure and ANP level were measured at baseline (before taking ARNI) and 3 weeks later. ARNI (200mg) was prescribed and maintained during the study. In addtion, the daily salt intake was calculated using creatinine and natrium levels in urine, age, and body weight according to Japanese hypertensive guideline at baseline and 3 weeks later. Results The average age was 70±8 years old. About 50% (N=23) was male. The mean sytolic and diastolic blood pressure was 148±14mmHg and 89±10mmHg, respectively. The mean daily salt intake was 9.5±2.2 g/day at baseline. The mean ANP level was 529±300pg/ml. At follow up (3 weeks later), the mean systolic and diastolic blood pressure significanly went down to 132± 18 mmHg and 70± 9 mmHg, respectively (p=0.03). ANP level also increased from 529±300pg/ml to 793±580pg/ml. However, the mean daily salt intake was almost same as the baseline at 9.4±3.2 g/day. The patients were divided into 2 groups; high daily salt intake (N=20 with mean daily salt intake 10.5±1.7g/day)) and low daily salt intake (N=24 with 8.4±3.1g/day) groups compared to the baseline. The absolute and percentage changes in systolic blood pressure were almost same in the high and low daily salt intake groups (-12.7±15.8mmHg vs -13.7±14.2mmHg, p=0.75; -5.8±6.5% vs.-7.0±9.6%, p=0.58, respectively). However, the change rate in ANP level was significantly higer in the high daily salt intake group than in the low daily salt intake group (155±63 vs. 12±16%, p=0.01). Conclusion ARNI demonstrates effectiveness in lowering the blood pressure even in patients with higher salt intake, unlike angiotensin receptor blocker. In cases with high salt intake, the notable increase in ANP levels may contribute to decreasing blood pressure through vasodilator and natriuretic action.

Magnetocardiographic imaging of Tpeak-Tend magnetic field dynamics discriminates between ventricular repolarization disorders due to mitral valve prolapse and to ischemic heart disease

Abstract Background Several etiopathogenetic mechanisms, including ischemia of the papillary muscles, abnormal catecholamine regulation, baroreflex modulation, and activation of atrial natriuretic peptide induced by abnormal stretch of the prolapsing mitral leaflets, have been suggested as possible causes of ventricular repolarization abnormalities (VRab) in patients (pts) with mitral valve prolapse (MVP) [1-3], especially in those with chest pain (CP). Purpose Since magnetocardiography (MCG) is a sensitive alternative to improve the detection of VRab, this study aimed to evaluate its discrimination accuracy to differentiate VRab due to MVP from those due to ischemic heart disease (IHD). Methods MCG recordings of 32 female patients (age 40.3±13.3 years) with MVP (at echocardiography), 20 of them with CP and/or palpitations, were retrospectively compared with those of 35 pts with IHD (at least one vessel stenosis >70%) (age 66.2±10.6 years), and with those of 32 age-matched (age 40.8±11.5 years) healthy females (HF) without MVP. The cardiac magnetic field (MF) component perpendicular to the anterior chest wall (Bz) was recorded with a 36-channel DC-SQUID MCG system (sensitivity ~30 fT/VHz). Thirteen MCG parameters, five derived from the analysis of the T-wave MF extrema dynamics, and eight from the effective magnetic vector (EMV) dynamics, were automatically calculated with proprietary software during the Tpeak-Tend interval (T3-T4 in Figure 1). Discriminant analysis (DA) was applied to separate groups. Results At univariate analysis, 11 MCG parameters were significantly different (p< 0.05) between MVP and IHD pts (Table 1). After multivariate analysis, 9 parameters (AzimuthMeanA, TrajectoryLengthRangeD, AngleDerivativeRangeD, AzimuthdiffAD, Q2AnalysisScore, AngleMinimum, AngleDynamics, DistanceDynamics, RatioDynamics) differentiated MVP and IHD pts’ VRab with 80% accuracy (cross-correlated), at DA. Moreover, in IHD pts abnormality of EMV dynamics extended also along the whole T-wave [4]. Three EMV parameters of the Tpeak-Tend interval (TrajectoryLengthRangeD, AzimuthdiffAD, Q2AnalysisScore), and three T-wave MF extrema parameters (AngleMinimum, Distance Dynamics, and Ratio Dynamics) were abnormal in 11 MVP pts, 10 of them with CP but normal ECG, and only one asymptomatic. Discussion: MCG EMV and MF dynamics calculated from rest-MCG data are reliable to identify VRab in pts with MVP and with IHD, differentiating them with a good discrimination accuracy. MCG VRa abnormality was mostly confined in the Tpeak-Tend interval in pts with MVP (in agreement with previous ECG findings [5]), while extended to the whole ST interval in IHD pts. Rest MCG is more sensitive than ECG in detecting VRab in pts with MVP and CP. Due to the limited number of investigated cases, the potential arrhythmogenicity of MVP-related VRab detected with MCG was not evaluated.Figure 1.MCG imaging of Tpeak-Tend MFTable 1

Intact DNA repair in differentiated cardiomyocytes is essential for maintaining cardiac function in response to pressure overload in mice

Abstract Introduction DNA in every cell is continuously damaged and DNA repair mechanisms are essential for protection against DNA damage-induced aging-related diseases. For example, deficient repair of endogenously generated DNA damage in mice with cardiomyocyte-restricted inactivation of Xpg, is associated with progressive heart failure. Purpose Here we tested the hypothesis that unrepaired DNA damage in differentiated cardiomyocytes increases cardiac vulnerability in response to hemodynamic overload. Methods To increase the burden of spontaneous DNA damage, we generated mice with cardiomyocyte-restricted inactivation of DNA repair endonuclease XPG. At 8 weeks of age, αMHC-Xpgc/- and control (Ctrl) mice were subjected to pressure overload by transverse aortic constriction (TAC). Eight weeks after TAC, left ventricular (LV) function was assessed using echocardiography and hemodynamic measurements, followed by molecular and histological analyses. Results Cardiomyocyte-restricted inactivation of Xpg resulted in systolic as well as diastolic LV dysfunction (Table). TAC-induced LV hypertrophy is similar in both groups (Ctrl 38%; αMHC-Xpgc/- 34%). In Ctrl mice, LV hypertrophy was accompanied by minimal LV dilation and modest changes in systolic and diastolic LV function. Conversely, TAC in αMHC-Xpgc/- produced severe LV dysfunction and resulted in overt congestive heart failure, demonstrated by aggravation of LV dilation, and marked increases in LV end-diastolic pressure, left atrial weight and lung fluid weight, which was accompanied by further increases in the expression levels of the hypertrophic marker genes atrial natriuretic peptide and beta-myosin heavy chain (Table). Moreover, lectin staining revealed a decrease in capillary density and TUNEL staining revealed further elevated levels of myocardial apoptosis. In addition, a significant increase of myocardial collagen content was observed. Conclusion Cardiomyocyte-restricted loss of DNA repair protein XPG increases cardiac vulnerability to develop heart failure in response to pressure overload. These findings underscore the importance of genomic stability for maintenance of cardiac function, not only during basal conditions, but also in response to a pathological stimulus.

Deficiencies in corin and atrial natriuretic peptide-mediated signaling impair endochondral ossification in bone development

Corin is a protease that activates atrial natriuretic peptide (ANP), a hormone in cardiovascular homeostasis. Structurally, ANP is similar to C-type natriuretic peptide (CNP) crucial in bone development. Here, we examine the role of corin and ANP in chondrocyte differentiation and bone formation. We show that in Corin and Nppa (encoding ANP) knockout (KO) mice, chondrocyte differentiation is impaired, resulting in shortened limb long bones. In adult mice, Corin and Nppa deficiency impairs bone density and microarchitecture. Molecular studies in cartilages from newborn Corin and Nppa KO mice and in cultured chondrocytes indicate that corin and ANP act in chondrocytes via cGMP-dependent protein kinase G signaling to inhibit mitogen-activated protein kinase phosphorylation and stimulate glycogen synthase kinase-3β phosphorylation and β-catenin upregulation. These results indicate that corin and ANP signaling regulates chondrocyte differentiation in bone development and homeostasis, suggesting that enhancing ANP signaling may improve bone quality in patients with osteoporosis.

The role and mechanism of NRG1/ErbB4 in inducing the differentiation of induced pluripotent stem cells into cardiomyocytes

BackgroundWe aimed to investigate the effect and potential mechanism of enhancing Neuregulin1 (NRG1)/v-erb-b2 avian erythroblastic leukemia viral oncogene homolog 4 (ErbB4) expression on the differentiation of induced pluripotent stem cells (iPSCs) into cardiomyocytes.MethodsWe utilized CRISPR-CAS9 technology to knock in ErbB4 and obtained a single-cell clone IPSN-AAVS1-CMV-ErbB4 (iPSCs-ErbB4). Subsequently, we induced the differentiation of iPSCs into cardiomyocytes and quantified the number of beating embryoid bodies. Furthermore, quantitative real-time PCR assessed the expression of cardiomyocyte markers, including ANP (atrial natriuretic peptide), Nkx2.5 (NK2 transcription factor related locus 5), and GATA4 (GATA binding protein 4). On the 14th day of differentiation, we observed the α-MHC (α-myosin heavy chain)-positive area using immunofluorescent staining and conducted western blotting to detect the expression of cTnT (cardiac troponin) protein and PI3K/Akt signaling pathway-related proteins. Additionally, we intervened the iPSCs-ErbB4 + NRG1 group with the PI3K/Akt inhibitor LY294002 and observed alterations in the expression of cardiomyocyte differentiation-related genes.ResultsThe number of beating embryoid bodies increased after promoting the expression of NRG1/ErbB4 compared to the iPSCs control group. Cardiomyocyte markers ANP, Nkx2.5, and GATA4 significantly increased on day 14 of differentiation, and the positive area of α-MHC was three times that of the iPSCs control group. Moreover, there was a marked increase in cTnT protein expression. However, there was no significant difference in cardiomyocyte differentiation between the iPSCs-ErbB4 group and the iPSCs control group. Akt phosphorylation was significantly increased in the iPSCs-ErbB4 + NRG1 group. LY294002 significantly reversed the enhancing effect of NRG1/ErbB4 overexpression on Akt phosphorylation as well as the increase in α-MHC and cTnT expression.ConclusionsIn conclusion, promoting the expression of NRG1/ErbB4 induced the differentiation of iPSC into cardiomyocytes, possibly through modulation of the PI3K/Akt signaling pathway.

Loss of atrial natriuretic peptide signaling causes insulin resistance, mitochondrial dysfunction, and low endurance capacity.

Type 2 diabetes (T2D) and obesity are strongly associated with low natriuretic peptide (NP) plasma levels and a down-regulation of NP guanylyl cyclase receptor-A (GCA) in skeletal muscle and adipose tissue. However, no study has so far provided evidence for a causal link between atrial NP (ANP)/GCA deficiency and T2D pathogenesis. Here, we show that both systemic and skeletal muscle ANP/GCA deficiencies in mice promote metabolic disturbances and prediabetes. Skeletal muscle insulin resistance is further associated with altered mitochondrial function and impaired endurance running capacity. ANP/GCA-deficient mice exhibit increased proton leak and reduced content of mitochondrial oxidative phosphorylation proteins. We further show that GCA is related to several metabolic traits in T2D and positively correlates with markers of oxidative capacity in human skeletal muscle. Together, these results indicate that ANP/GCA signaling controls muscle mitochondrial integrity and oxidative capacity in vivo and plays a causal role in the development of prediabetes.

Atrial natriuretic peptide (ANP) modulates stress-induced autophagy in endothelial cells

Atrial natriuretic peptide (ANP), a cardiac hormone involved in the regulation of water/sodium balance and blood pressure, is also secreted by endothelial cells, where it exerts protective effects in response to stress. Autophagy is an intracellular self-renewal process involved in the degradation of dysfunctional cytoplasmic elements. ANP was recently reported to act as an extracellular regulator of cardiac autophagy. However, its role in the regulation of endothelial autophagy has never been investigated. Here, we tested the effects of ANP in the regulation of autophagy in human umbilical vein endothelial cells (HUVECs). We found that ANP rapidly increases autophagy and autophagic flux at physiological concentrations through its predominant pathway, mediated by natriuretic peptide receptor type A (NPR-A) and protein kinase G (PKG). We further observed that ANP is rapidly secreted by HUVEC under stress conditions, where it mediates stress-induced autophagy through autocrine and paracrine mechanisms. Finally, we found that the protective effects of ANP in response to high-salt loading or tumor necrosis factor (TNF)-α are blunted by concomitant inhibition of autophagy. Overall, our results suggest that ANP acts as an endogenous autophagy activator in endothelial cells. The autophagy mechanism mediates the protective endothelial effects exerted by ANP.

The transcription factor PPARA mediates SIRT1 regulation of NCOR1 to protect damaged heart cells.

Heart failure (HF) is a clinical syndrome with a high risk. Our previous research showed a regulatory relationship between Sirtuin 1 (SIRT1), peroxisome proliferator-activated receptor α (PPARA) and nuclear receptor co-repressor 1 (NCOR1). This study aimed to investigate the regulatory mechanism of SIRT1/PPARA/NCOR1 axis in HF. HF models in vitro were established by doxorubicin (DOX)-induced AC16 and human cardiac microvascular endothelial cell (HCMEC) lines. The contents of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), interleukin-1β (IL-1β), and IL-18 were detected using enzyme-linked immunosorbent assay. Then, we assessed the levels of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD) and adenosine triphosphate (ATP). Moreover, the relationship between SIRT1 and PPARA was detected using the co-immunoprecipitation (Co-IP) analysis. The connection between PPARA and NCOR1 was analyzed using chromatin immunoprecipitation (ChIP). Overexpression of SIRT1 or PPARA could reduce apoptosis in DOX-induced AC16 and HCMEC cells, the levels of IL-1β, IL-18, ANP, BNP, ROS and MDA, while increasing the levels of SOD and ATP. In addition, overexpression of PPARA could increase the viability of DOX-induced cells and the levels of myosin heavy chain 6 (Myh6) and Myh7. Co-IP showed that SIRT1 interacted with PPARA. Silencing PPARA could reverse the effect of SIRT1 overexpression on DOX-induced AC16 and HCMEC cells. ChIP assay demonstrated that PPARA could bind to the promoter region of NCOR1. Silencing NCOR1 could reverse the effect of PPARA overexpression on DOX-induced AC16 and HCMEC cells. This study revealed that PPARA could mediate SIRT1 to promote NCOR1 expression and thus protect damaged heart cells. The finding provided an important reference for the treatment of HF.

Mitochondrial Dysfunction Plays a Relevant Role in Heart Toxicity Caused by MeHg.

The effects of methylmercury (MeHg) on exposed populations are a public health problem. In contrast to widely studied neurological damage, few cardiovascular changes have been described. Our group evaluated the cardiotoxicity of a cumulative dose of 70 mg.kg-1 fractioned over a 14-day exposure period in mice (MeHg70 group). The effects of MeHg on proteins relevant to cardiac mitochondrial function were also investigated. The results obtained showed a reduction in oxygen consumption in the two settings. In cardiac tissue samples in oxygraphy studies, this reduction was related to a lower efficiency of complexes II and V, which belong to the oxidative phosphorylation system. In vivo, mice in the MeHg70 group presented lower oxygen consumption and running tolerance, as shown by ergometric analyses. Cardiac stress was evident in the MeHg70 group, as indicated by a marked increase in the level of the mRNA encoding atrial natriuretic peptide. Electrocardiogram studies revealed a lower heart rate at rest in the animals from the MeHg70 group, as well as prolonged left ventricular depolarisation and repolarisation. Through echocardiographic analysis, reductions in the left ventricular ejection fraction and left ventricular wall thickness of approximately 10% and 20%, respectively, were detected. These results indicate that the oral intake of MeHg can decrease cardiac function and oxidative metabolism. This finding highlights the importance of monitoring MeHg levels in humans and animals in contaminated areas, as well as periodically carrying out cardiac function tests.

Atrial Natriuretic Peptide and Cardiovascular Diseases in Dogs and Cats

The term biomarker encompasses various biological indicators that objectively reflect a patient's medical status with precision and reproducibility. These indicators range from basic measurements like pulse and blood pressure to more intricate laboratory tests. Cardiac markers are crucial for accurate and prompt diagnosis of heart diseases in animals. Given the challenge of diagnosing cardiac diseases in small animals due to nonspecific clinical signs, cardiac markers provide quantitative indicators of biological processes. These markers include cardiac troponins for myocardial injury, natriuretic peptides for myocardial function, lipoproteins for serum homeostasis, and markers for inflammation of the cardiovascular system. Among natriuretic peptides, atrial natriuretic peptide (ANP) has emerged as a significant tool in diagnosing and monitoring cardiac diseases. ANP, primarily synthesized in cardiac atria, regulates salt and fluid excretion, counteracts vasoconstriction, and inhibits the renin-angiotensin-aldosterone system, contributing to the maintenance of cardiovascular homeostasis. Additionally, it functions as a biomarker for ventricular hypertrophy and congestive heart failure (CHF) in animals. Furthermore, it protects against hypertension and cardiac remodeling by demonstrating antagonism to the same system. This review addresses the definition of biomarkers within the context of molecular biology, elucidates their multifaceted functions in the animal organism in light of integrative physiology, and explores the pathologies correlated with ANP, with an emphasis on its etiopathogenesis and clinical manifestations.

Cholecystokinin regulates atrial natriuretic peptide secretion through activation of NOX4–Sirt1–LEF1 signaling in beating rat hypoxic atria

The mammalian cardiac myocytes not only synthesize and secrete atrial natriuretic peptide (ANP), but also express cholecystokinin (CCK) and its receptors (CCK1R and CCK2R). However, atrial CCK expression patterns and its effects on ANP secretion during hypoxia are unclear. Therefore, this study is aimed to investigate the effect of hypoxia on the expression levels of CCK and its receptors, as well as the underlying mechanisms involved in regulating hypoxia-induced ANP secretion in isolated beating atria. The results of this study showed that acute hypoxia significantly upregulated expression of CCK and CCK1R as well as CCK2R through activation of hypoxia-inducible factor 1α–apelin signaling. Endogenous CCK induced by hypoxia markedly upregulated the expression of silent information regulator factor 2-related enzyme 1 (Sirt1) and its downstream nuclear factor erythroid‑2‑related factor 2 (Nrf2) via the activation of nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4), leading to increase of activating T cell factor (TCF) 3 and TCF4/ lymphoid enhancer factor (LEF) 1, ultimately promoting hypoxia-induced ANP secretion. In addition, siRNA-mediated knockdown of LEF1 dramatically attenuated hypoxia-induced increase of ANP expression in HL-1 atrial myocytes. These results indicated endogenous CCK induced by hypoxia promoted hypoxia-induced ANP secretion by activation of NOX4–Sirt1–TCF3/4–LEF1 signaling pathway.

Identification of natriuretic peptide receptor A-related gene expression signatures in podocytes in vivo reveals baseline control of protective pathways.

Natriuretic peptide receptor-A (NPR-A) is the principal receptor for the natriuretic peptides atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP). Targeted deletion of NPR-A in mouse glomerular podocytes significantly enhances renal injury in vivo in the DOCA-salt experimental model. It was therefore hypothesized that natriuretic peptides exert a direct protective effect on glomerular barrier integrity through activation of NPR-A and modulation of gene expression patterns in podocytes. Green fluorescence-positive podocytes from mice with a conditional deletion of Npr1 encoding NPR-A were isolated by fluorescence-activated cell sorting (FACS). Differentially expressed genes (DEGs) in podocytes were identified by RNA sequencing of podocytes from wild-type and NPR-A-deleted mice. Enrichment analysis was performed on the DEGs using Gene Ontology (GO) terms. Identified transcripts were validated by real-time PCR and ELISA of cultured isolated human and mouse glomeruli. In addition, the effect of natriuretic peptides on podocyte migration was investigated by measuring the outgrowth of podocytes from cultured glomeruli. A total of 158 DEGs were identified with 81 downregulated DEGs and 77 upregulated DEGs in Npr1-deficient podocytes. Among the downregulated genes were protein S and semaphorin 3G, which are known to have protective effects in podocytes. Protein S was also expressed in and secreted from isolated human glomeruli. GO enrichment analysis revealed that the upregulated DEGs in NPR-A deficient podocytes were associated with cell migration and motility. In line, BNP significantly decreased podocyte outgrowth from cultured glomeruli. In conclusion, endogenous levels of natriuretic peptides in mice support baseline protective pathways at glomerular podocytes such as protein S and suppress podocyte migration.NEW & NOTEWORTHY A combination of fluorescence-activated cell sorting and RNA sequencing identified 158 changed gene products in adult mouse kidneys with and without podocyte-specific deletion of the natriuretic peptide receptor A. Downregulated products included protein S and semaphorin 3G, both with proven renoprotective impact, whereas upregulated products were related to mobility of podocytes. Protein S was produced and released from human and murine isolated glomeruli, and atrial natriuretic peptide (ANP) led to decreased migration of podocytes.

The functional role of m6A demethylase ALKBH5 in cardiomyocyte hypertrophy

Cardiomyocyte hypertrophy is a major outcome of pathological cardiac hypertrophy. The m6A demethylase ALKBH5 is reported to be associated with cardiovascular diseases, whereas the functional role of ALKBH5 in cardiomyocyte hypertrophy remains confused. We engineered Alkbh5 siRNA (siAlkbh5) and Alkbh5 overexpressing plasmid (Alkbh5 OE) to transfect cardiomyocytes. Subsequently, RNA immunoprecipitation (RIP)-qPCR, MeRIP-qPCR analysis and the dual-luciferase reporter assays were applied to elucidate the regulatory mechanism of ALKBH5 on cardiomyocyte hypertrophy. Our study identified ALKBH5 as a new contributor of cardiomyocyte hypertrophy. ALKBH5 showed upregulation in both phenylephrine (PE)-induced cardiomyocyte hypertrophic responses in vitro and transverse aortic constriction (TAC)/high fat diet (HFD)-induced pathological cardiac hypertrophy in vivo. Knockdown or overexpression of ALKBH5 regulated the occurrence of hypertrophic responses, including the increased cardiomyocyte surface areas and elevation of the hypertrophic marker levels, such as brain natriuretic peptide (BNP) and atrial natriuretic peptide (ANP). Mechanically, we indicated that ALKBH5 activated JAK2/STAT3 signaling pathway and mediated m6A demethylation on Stat3 mRNA, but not Jak2 mRNA, resulting in the phosphorylation and nuclear translocation of STAT3, which enhances the transcription of hypertrophic genes (e.g., Nppa) and ultimately leads to the emergence of cardiomyocytes hypertrophic growth. Our work highlights the functional role of ALKBH5 in regulating the onset of cardiomyocyte hypertrophy and provides a potential target for hypertrophic heart diseases prevention and treatment.ALKBH5 activated JAK2/STAT3 signaling pathway and mediated m6A demethylation on Stat3 mRNA, but not Jak2 mRNA, resulting in the phosphorylation and nuclear translocation of STAT3, which enhances the transcription of hypertrophic genes (e.g., Nppa) and ultimately leads to the emergence of cardiomyocytes hypertrophic growth.

Changes in urinary output due to concomitant administration of sacubitril/valsartan and atrial natriuretic peptide in patients with heart failure: a multicenter retrospective cohort study

BackgroundSacubitril/valsartan is an angiotensin receptor neprilysin inhibitor (ARNI) that inhibits the degradation of endogenous natriuretic peptides. Therefore, ARNIs may increase the efficacy of human atrial natriuretic peptide (hANP), a drug for acute heart failure, by mediating its pharmacological mechanism. This study was aimed at evaluating the effects of ARNIs on the pharmacological effects of hANP by using surrogate marker, such as urinary output, in patients with heart failure.MethodsIn this multicenter retrospective cohort study, adult patients with heart failure who were taking angiotensin II receptor blockers (ARB) or ARNIs combined with hANP were enrolled. Information on basic characteristics, clinical laboratory data, medical history, and severity of cardiac insufficiency were collected from electronic medical records. The primary outcome was the change in adjusted fluid balance, calculated by IN-volume (mL/day) – OUT-volume (mL/day) / daily hANP dosage (μg).ResultsNinety-two and 62 patients in the ARB + hANP and ARNI + hANP groups, respectively, were eligible for analysis. The adjusted fluid balance in the ARNI + hANP group was significantly lower than that in the ARB + hANP group (p = 0.001). After propensity score matching, 27 patients from each group were included. Similarly, there was a significant reduction in adjusted fluid balance in the ARNI + hANP group after propensity score matching (p = 0.026).ConclusionsThese findings suggest that ARNIs may enhance the efficacy of hANP and the combination of the two may be effective in the treatment of heart failure.