Search

The mammalian cardiac myocytes not only synthesize and secrete atrial natriuretic peptide (ANP), but also express cholecystokinin (CCK) and its receptors (CCK 1 R and CCK 2 R). 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 CCK 1 R as well as CCK 2 R 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., Competing Interests: Declaration of Competing Interest All contributing authors declare no conflicts of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Cardiovascular 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., Methods: Liver 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., Results: We 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., Conclusions: Our 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., (© 2024. The Author(s).)

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., (© 2024. The Author(s).)

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) plays an important role in blood pressure regulation. Low levels of ANP correlate with the development of salt-sensitive hypertension (SS-HTN). Our previous studies indicated that ANP deficiency exacerbated renal function decline in SS-HTN. In the heart and fat tissue, ANP was reported to affect lipid peroxidation and mitochondrial bioenergetics but the effects of ANP on mitochondrial function in the kidney are unexplored. We hypothesized that ANP deficiency in SS-HTN causes renal bioenergetic shift, leading to disruption of mitochondrial network and oxidative stress. To address the hypothesis, we placed Dahl SS wild-type (SS WT ) and ANP knockout (SS NPPA-/- ) rats on 4% NaCl high salt (HS) diet to induce HTN or maintained them on 0.4% NaCl normal salt (NS) diet and assessed mitochondrial bioenergetics and dynamics using spectrofluorimetry, Seahorse assay, electron paramagnetic resonance (EPR) spectroscopy, Western blotting, electron microscopy, PCR and cytokine assays. We report that under high salt conditions, associated with hypertension and renal damage, the SS NPPA-/- rats exhibit a decrease in mitochondrial membrane potential and elevation in mitochondrial ROS levels compared to SS WT . The redox shift is also evident by the presence of more pronounced medullar lipid peroxidation in the SS NPPA-/- strain. We also revealed fragmented, more damaged mitochondria in the SS NPPA-/- rats, accompanied by increased turnover and biogenesis. Overall, our data indicate that ANP deficiency causes disruptions in mitochondrial bioenergetics and dynamics which likely contributes to aggravation of the renal damage and hypertension in the Dahl SS rat; the major pathological effects are evident in the groups subjected to a combined salt and ANP deficiency-induced mitochondrial stress., (© 2024 The Author(s). The FASEB Journal published by Wiley Periodicals LLC on behalf of Federation of American Societies for Experimental Biology.)

Atrial natriuretic peptide (ANP) plays a central role in the regulation of blood pressure and volume. ANP activities are mediated by natriuretic peptide receptor-A (NPR-A), a single-pass transmembrane receptor harboring intrinsic guanylate cyclase activity. This study investigated the mechanism underlying NPR-A-dependent hormone recognition through the determination of the crystal structures of the NPR-A extracellular hormone-binding domain complexed with full-length ANP, truncated mutants of ANP, and dendroaspis natriuretic peptide (DNP) isolated from the venom of the green Mamba snake, Dendroaspis angusticeps. The bound peptides possessed pseudo-two-fold symmetry, despite the lack of two-fold symmetry in the primary sequences, which enabled the tight coupling of the peptide to the receptor, and evidently contributes to guanylyl cyclase activity. The binding of DNP to the NPR-A was essentially identical to that of ANP; however, the affinity of DNP for NPR-A was higher than that of ANP owing to the additional interactions between distinctive sequences in the DNP and NPR-A. Consequently, our findings provide valuable insights that can be applied to the development of novel agonists for the treatment of various human diseases., (© 2024 The Authors. The FEBS Journal published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)

Background: Atrial Fibrillation (AF), a prevalent arrhythmic condition, is intricately associated with atrial fibrosis, a major pathological contributor. Central to the development of atrial fibrosis is myocardial inflammation. This study focuses on Atrial Natriuretic Peptide (ANP) and its role in mitigating atrial fibrosis, aiming to elucidate the specific mechanisms by which ANP exerts its effects, with an emphasis on fibroblast dynamics., Methods and Results: The study involved forty Sprague-Dawley rats, divided into four groups: control, Angiotensin II (Ang II), Ang II + ANP, and ANP only. The administration of 1 µg/kg/min Ang II was given to Ang II and Ang II + ANP groups, while both Ang II + ANP and ANP groups received 0.1 µg/kg/min ANP intravenously for a duration of 14 days. Cardiac fibroblasts were used for in vitro validation of the proposed mechanisms. The study observed that rats in the Ang II and Ang II + ANP groups showed an increase in blood pressure and a decrease in body weight, more pronounced in the Ang II group. Diastolic dysfunction, a characteristic of the Ang II group, was alleviated by ANP. Additionally, ANP significantly reduced Ang II-induced atrial fibrosis, myofibroblast proliferation, collagen overexpression, macrophage infiltration, and the elevated expression of Interleukin 6 (IL-6) and Tenascin-C (TN-C). Transcriptomic sequencing indicated enhanced PI3K/Akt signaling in the Ang II group. Furthermore, in vitro studies showed that ANP, along with the PI3K inhibitor LY294002, effectively reduced PI3K/Akt pathway activation and the expression of TN-C, collagen-I, and collagen-III, which were induced by Ang II., Conclusions: The study demonstrates ANP's potential in inhibiting myocardial inflammation and reducing atrial fibrosis. Notably, ANP's effect in countering atrial fibrosis seems to be mediated through the suppression of the Ang II-induced PI3K/Akt-Tenascin-C signaling pathway. These insights enhance our understanding of AF pathogenesis and position ANP as a potential therapeutic agent for treating atrial fibrosis., (© 2024. The Author(s).)

Introduction: Dimenhydrinate and scopolamine are frequently used drugs, but they cause drowsiness and performance decrement. Therefore, it is crucial to find peripheral targets and develop new drugs without central side effects. This study aimed to investigate the anti-motion sickness action and inner ear-related mechanisms of atrial natriuretic peptide (ANP)., Methods: Endolymph volume in the inner ear was measured with magnetic resonance imaging and expression of AQP2 and p-AQP2 was detected with Western blot analysis and immunofluorescence method., Results: Both rotational stimulus and intraperitoneal arginine vasopressin (AVP) injection induced conditioned taste aversion (CTA) to 0.15% sodium saccharin solution and an increase in the endolymph volume of the inner ear. However, intraperitoneal injection of ANP effectively alleviated the CTA behaviour and reduced the increase in the endolymph volume after rotational stimulus. Intratympanic injection of ANP also inhibited rotational stimulus-induced CTA behaviour, but anantin peptide, an inhibitor of ANP receptor A (NPR-A), blocked this inhibitory effect of ANP. Both rotational stimulus and intraperitoneal AVP injection increased the expression of AQP2 and p-AQP2 in the inner ear of rats, but these increases were blunted by ANP injection. In in vitro experiments, ANP addition decreased AVP-induced increases in the expression and phosphorylation of AQP2 in cultured endolymphatic sac epithelial cells., Conclusion: Therefore, the present study suggests that ANP could alleviate motion sickness through regulating endolymph volume of the inner ear increased by AVP, and this action of ANP is potentially mediated by activating NPR-A and antagonising the increasing effect of AVP on AQP2 expression and phosphorylation., (© 2024 S. Karger AG, Basel.)

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., (© 2023 The Authors. British Journal of Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.)

Atrial natriuretic peptide (ANP) is a peptide hormone that regulates blood pressure and volume. ANP interacts with natriuretic peptide receptor-A (NPR-A) to lower the blood pressure through vasodilation, diuresis and natriuresis. Previously, we designed two human ANP analogues, one with exclusively diuretic function (DGD-ANP) and the other with exclusively vasodilatory function (DRD-ANP). Although both ANP analogues interact with NPR-A, their ability to produce cGMP was different. Three alternatively spliced isoforms of NPR-A were previously identified in rodents. Here, we evaluated the putative human isoforms for their cGMP production independently and in combination with WT NPR-A in various percentages. All three NPR-A isoforms failed to produce cGMP in the presence of ANP, DGD-ANP, or DRD-ANP. Co-expression of isoforms with WT NPR-A were found to significantly impair cGMP production. Considering the differential tissue expression levels of all three spliced isoforms in rodents have previously been demonstrated, the existence of these non-functional receptor isoforms may act as negative regulator for ANP/NPR-A activation and fine-tune cGMP production by WT NPR-A to different degree in different tissues. Thus, NPR-A isoforms potentially contribute to tissue-specific functions of ANP., (© 2023. The Author(s).)

Introduction: Atrial natriuretic peptide (ANP), a hormone secreted from the heart, controls cardiovascular and renal functions including arterial blood pressure and natriuresis. ANP also exerts metabolic effects in adipose tissue, liver and skeletal muscle, and interacts with the secretion of adipokines. We tested the hypothesis that ANP lowers concentrations of the anorexigenic adipokine leptin in healthy humans in vivo ., Methods: Human ANP or matching placebo was infused intravenously (iv) into healthy men in a controlled clinical trial., Results: Within 135 minutes of iv ANP infusion, we observed an acute decrease in plasma leptin levels compared to controls. Free fatty acids markedly increased with ANP infusion in vivo , indicating activated lipolysis. In human SGBS adipocytes, ANP suppressed leptin release., Discussion: The study shows that the cardiac hormone ANP reduces the levels of the anorexigenic adipokine leptin in healthy humans, providing further support for ANP as a cardiomyokine in a heart - adipose tissue axis. (registered in the German Clinical Trials Register and the WHO International Clinical Trials Registry Platform was granted under DRKS00024559 )., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Daniels, Fischer-Posovszky, Boschmann, Jumpertz-von Schwartzenberg, Müller, Sandforth, Frank-Podlech, Hülskämper, Peter, Wabitsch, Jordan and Birkenfeld.)

Atrial natriuretic peptide (ANP) has been considered to exert an essential role as a cardiac secretory hormone in the regulation of hemodynamic homeostasis. As the research progresses, the role of ANP in the crosstalk between heart and lipid metabolism has become an interesting topic that is attracting the interest of researchers. The regulation of ANP in lipid metabolism shows favorable effects, particularly the activation of brown adipose tissue (BAT). The complex regulatory network of ANP on BAT has not been fully outlined. This narrative review critically evaluated the existing literature on the regulatory effects of ANP on BAT. In general, we have summarized the expression of ANP and its receptors in various human tissues, analyzed the progress of research on the relationship between the ANP and BAT, and described several potential pathways of ANP to BAT. Exogenous ANP, natriuretic peptide receptor C (NPRC) deficiency, cold exposure, bariatric surgery, and cardiac or renal insufficiency could all contribute to BAT expression by increasing circulating ANP levels., (© 2022 World Obesity Federation.)

Cardiac natriuretic peptides (NPs), atrial NP (ANP) and B-type NP (BNP) are true hormones produced and released by cardiomyocytes, exerting several systemic effects. Together with C-type NP (CNP), mainly expressed by endothelial cells, they also exert several paracrine and autocrine activities on the heart itself, contributing to cardiovascular (CV) health. In addition to their natriuretic, vasorelaxant, metabolic and antiproliferative systemic properties, NPs prevent cardiac hypertrophy, fibrosis, arrhythmias and cardiomyopathies, counteracting the development and progression of heart failure (HF). Moreover, recent studies revealed that a protein structurally similar to NPs mainly produced by skeletal muscles and osteoblasts called musclin/osteocrin is able to interact with the NPs clearance receptor, attenuating cardiac dysfunction and myocardial fibrosis and promoting heart protection during pathological overload. This narrative review is focused on the direct activities of this molecule family on the heart, reporting both experimental and human studies that are clinically relevant for physicians.

Objective: A-kinase anchoring protein 5 (AKAP5) is involved in ventricular remodeling in rats with heart failure after myocardial infarction; however, the specific mechanism is not clear. This study investigated whether AKAP5 anchors calcineurin (CaN) to regulate the remodeling of H9c2 cardiomyocytes., Methods: H9c2 cells were subjected to hypoxia stress for 3 h and reoxygenation for 24 h to create a hypoxia-reoxygenation (H/R) model. These cells were divided into three groups: H/R (model), empty vector +H/R (NC), and siRNA-AKAP5+H/R (siRNA-AKAP5) groups. The non-H/R H9c2 cells were used as normal controls. Western blotting was used to detect cardiac hypertrophy-related protein expression in the cells, including atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), beta myosin heavy chain (β-MHC), and phosphorylated nuclear factor of activated T-cell 3 (p-NFATc3). Phalloidin staining was used to label the cytoskeleton and the cell area in different groups was measured. Immunofluorescence staining and coimmunoprecipitation were used to study the relationship between AKAP5 and CaN. H9c2 cells pretreated with the CaN inhibitor FK506 were used to further verify the relationship between AKAP5 and CaN., Results: In the siRNA-AKAP5+H/R group, the expression level of cardiac hypertrophy-related proteins (ANP, BNP, and β-MHC) and CaN and the area of cardiomyocytes were significantly increased, while the p-NFATc3/NFATc3 ratio was decreased in H9c2H/R cells. AKAP5 and CaN proteins were colocalized and interacted in the cells. The CaN inhibitor significantly suppressed the expression of CaN, increased the p-NFATc3/NFATc3 ratio, and reduced the expression levels of ANP, BNP, and β-MHC proteins in the cells with low AKAP5 expression., Conclusions: AKAP5 downregulation aggravated the remodeling of cardiomyocytes after H/R. AKAP5 may anchor CaN to form a complex, which in turn activates NFATc3 dephosphorylation and expression of hypertrophy-related proteins., Competing Interests: Conflict of Interest The authors have declared that no competing interests exist., (Copyright © 2022 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

G protein-coupled receptors (GPCRs) are the largest family of membrane receptors that mediate the effects of cardiac diseases. GPR30, also named G-protein-coupled estrogen receptor, shows beneficial effect on female patients with heart failure. This research aimed to probe the role and mechanism of GPR30 in myocardial hypertrophy. The model of cardiac hypertrophy was induced by infusion of angiotensin (Ang) II in mice, and was induced by Ang II treatment in neonatal rat cardiomyocyte (NRCM). The mouse model of myocardial hypertrophy was induced by angiotensin (Ang) Ⅱ, and the neonatal rat cardiomyocyte (NRCM) was induced by Ang Ⅱ treatment. GPR30 agonist G1 reduced cardiac hypertrophy induced by Ang II in mice, and reduced cardiac atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and β-myosin heavy chain (β-MHC) induced by Ang II. Ang Ⅱ treatment of myocardial fibrosis in mice was suppressed after administration of G1. GPR30 deficiency produced the opposite results. Oxidative stress and apoptosis were enhanced in the mice heart induced by Ang II, which were suppressed by G1 administration, but were further exacerbated after GPR30 deficiency. The outcomes demonstrated that GPR30 participated in the regulation of cardiac hypertrophy and fibrosis. Activation of GPR30 ameliorated cardiac hypertrophy and fibrosis by reducing oxidative stress and apoptosis., (Copyright © 2022. Published by Elsevier Inc.)

Atrial natriuretic peptide (ANP) protects against acute lung injury (ALI), but the receptor that mediates this effect is not known. Transgenic mice with 0 (knockout), 1 (heterozygote), or 2 (wild-type) functional copies of Npr3 , the gene that encodes for natriuretic peptide receptor-C (NPR-C), were treated with intravenous infusion of ANP or saline vehicle before oropharyngeal aspiration of Pseudomonas aeruginosa (PA103) or saline vehicle. Lung injury was assessed 4 h following aspiration by measurement of lung wet/dry (W/D) weight, whole lung leukocyte and cytokine levels, and protein, leukocyte, and cytokine concentration in bronchoalveolar lavage fluid (BALF). PA103 induced acute lung injury as evidenced by increases in lung W/D ratio and protein concentration in BALF. The severity of PA103-induced lung injury did not differ between NPR-C genotypes. Treatment with intravenous ANP infusion reduced PA103-induced increases in lung W/D and BALF protein concentration in all three NPRC genotypes. PA103 increased the percentage of leukocytes that were neutrophils and cytokine levels in whole lung and BALF in NPR-C wild-type and knockout mice. This effect was blunted by ANP in wild-type mice but not in the NPR-C knockout mice. NPR-C does not mediate the protective effect of ANP on endothelial cell permeability in settings of PA103-induced injury but may mediate the effect of ANP on inhibition of the recruitment of neutrophils to the lung and thereby attenuate the release of inflammatory cytokines.

We have previously demonstrated that exogenous ketosis reduces urine production during exercise. However, the underlying physiological mechanism of this antidiuretic effect remained unclear. Therefore, we investigated whether acute exogenous ketosis by oral ingestion of ketone ester (KE) during a simulated cycling race (RACE) affects the hormonal pathways implicated in fluid balance regulation during exercise. In a double-blind crossover design, 11 well-trained male cyclists participated in RACE consisting of a 3-h submaximal intermittent cycling (IMT 180' ) bout followed by a 15-min time trial (TT 15' ) in an environmental chamber set at 28°C and 60% relative humidity. Fluid intake was adjusted to maintain euhydration. Before and during RACE, the subjects received either a control drink (CON) or the ketone ester (R)-3-hydroxybutyl (R)-3-hydroxybutyrate (KE), which elevated blood β-hydroxybutyrate to ∼2-4 mM. Urine output during IMT 180' was ∼20% lower in KE (1,172 ± 557 mL) than in CON (1,431 ± 548 mL, P < 0.05). Compared with CON, N-terminal proatrial natriuretic peptide (NT-pro ANP) concentration during RACE was ∼20% lower in KE ( P < 0.05). KE also raised plasma noradrenaline concentrations during RACE. Performance in TT 15' was similar between CON and KE. In conclusion, exogenous ketosis suppresses diuresis and downregulates NT-pro ANP secretion during exercise. NEW & NOTEWORTHY We previously demonstrated that exogenous ketosis reduces urine production during exercise, however, the underlying physiological mechanism remained unclear. Here, we, for the first time demonstrate that exogenous ketosis suppresses the exercise-induced release of atrial natriuretic peptide (ANP). However, given the limited effects of ANP on renal haemodynamics during exercise, the underlying physiological mechanism remains unknown. But downregulation of ANP might explain a new physiological mechanism by which exogenous ketosis lowers blood-free fatty acid levels.

Aims: The cardiac natriuretic peptides [atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP)] are important regulators of cardiovascular physiology, with reduced natriuretic peptide (NP) activity linked to multiple human cardiovascular diseases. We hypothesized that deficiency of either ANP or BNP would lead to similar changes in left ventricular structure and function given their shared receptor affinities., Methods and Results: We directly compared murine models deficient of ANP or BNP in the same genetic backgrounds (C57BL6/J) and environments. We evaluated control, ANP-deficient (Nppa-/-) or BNP-deficient (Nppb-/-) mice under unstressed conditions and multiple forms of pathological myocardial stress. Survival, myocardial structure, function and electrophysiology, tissue histology, and biochemical analyses were evaluated in the groups. In vitro validation of our findings was performed using human-derived induced pluripotent stem cell cardiomyocytes (iPS-CMs). In the unstressed state, both ANP- and BNP-deficient mice displayed mild ventricular hypertrophy which did not increase up to 1 year of life. NP-deficient mice exposed to acute myocardial stress secondary to thoracic aortic constriction (TAC) had similar pathological myocardial remodelling but a significant increase in sudden death. We discovered that the NP-deficient mice are more susceptible to stress-induced ventricular arrhythmias using both in vivo and ex vivo models. Mechanistically, deficiency of either ANP or BNP led to reduced myocardial cGMP levels and reduced phosphorylation of the cAMP response element-binding protein (CREBS133) transcriptional regulator. Selective CREB inhibition sensitized wild-type hearts to stress-induced ventricular arrhythmias. ANP and BNP regulate cardiomyocyte CREBS133 phosphorylation through a cGMP-dependent protein kinase 1 (PKG1) and p38 mitogen-activated protein kinase (p38 MAPK) signalling cascade., Conclusions: Our data show that ANP and BNP act in a non-redundant fashion to maintain myocardial cGMP levels to regulate cardiomyocyte p38 MAPK and CREB activity. Cardiac natriuretic peptide deficiency leads to a reduction in CREB signalling which sensitizes the heart to stress-induced ventricular arrhythmias., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.)

Midkine levels are related to various diseases, including cardiovascular disease, renal disease and autoimmune disease. The research aimed to investigate the mitigation influence of downregulation of intermediate factors on myocardial hypertrophy induced by angiotensin Ⅱ (Ang), and whether downregulation of midkine could attenuate oxidative stress and autophagy. Induced myocardial hypertrophy of the mice model and treated HL-1 cells with Ang Ⅱ in vitro. The expressions of midkine were increased in the model and HL-1 cells with Ang II treatment. Midkine silence alleviated cardiac hypertrophy induced by Ang II, and inhibited the increases of atrial natriuretic peptide (ANP), Brain natriuretic peptide (BNP) and beta-myosin heavy chain (β-MHC) in the heart of mice. The raises of ANP, BNP and β-MHC in Ang II-induced HL-1 cells were also suppressed after midkine downregulation. Downregulating of midkine inhibited the increases of oxidative stress markers 8-OHdG, superoxide anions and MDA in the heart of mice or in the Ang II-treated HL-1 cells. The raises of LC3B, Atg3, Atg5 and Beclin1 in mice heart and in the Ang II.-induced HL-1 cells were attenuated after midkine silence. These outcomes showed that midkine was upregulated in myocardial hypertrophy mice. Targeting of midkine could alleviate cardiac hypertrophy via attenuation of oxidative stress and autophagy., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Atrial natriuretic peptide (ANP), a canonical cardiac hormone, is mainly secreted from atrial myocytes and is involved in the regulation of body fluid, blood pressure homeostasis, and antioxidants. Cholecystokinin (CCK) is also found in cardiomyocytes as a novel cardiac hormone and induces multiple cardiovascular regulations. However, the direct role of CCK on the atrial mechanical dynamics and ANP secretion is unclear. The current study was to investigate the effect of CCK octapeptide (CCK-8) on the regulation of atrial dynamics and ANP secretion. Experiments were performed in isolated perfused beating rat atria. ANP was measured using radioimmunoassay. The levels of hydrogen peroxide (H 2 O 2 ) and arachidonic acid (AA) were determined using ELISA Kits. The levels of relative proteins and mRNA were detected by Western blot and RT-qPCR. The results showed that sulfated CCK-8 (CCK-8s) rather than desulfated CCK-8 increased the levels of phosphorylated cytosolic phospholipase A2 and AA release through activation of CCK receptors. This led to the upregulation of NADPH oxidase 4 (NOX4) expression levels and H 2 O 2 production and played a negative inotropic effect on atrial mechanical dynamics via activation of ATP-sensitive potassium channels and large-conductance calcium-activated potassium channels. In addition, CCK-8s-induced NOX4 subsequently upregulated peroxisome proliferator-activated receptor γ (PPAR γ ) coactivator-1 α (PGC-1 α ) expression levels through activation of p38 mitogen-activated protein kinase as well as the serine/threonine kinase signaling, ultimately promoting the secretion of ANP via activation of PPAR α and PPAR γ . In the presence of the ANP receptor inhibitor, the CCK-8-induced increase of AA release, H 2 O 2 production, and the upregulation of NOX4 and CAT expressions was augmented but the SOD expression induced by CCK-8s was repealed. These findings indicate that CCK-8s promotes the secretion of ANP through activation of NOX4-PGC-1 α -PPAR α /PPAR γ signaling, in which ANP is involved in resistance for NOX4 expression and ROS production and regulation of SOD expression., Competing Interests: The authors declare that there is no conflict of interest in this article., (Copyright © 2022 Zhuo-na Han et al.)

Background and Purpose: cGMP underpins the bioactivity of NO and natriuretic peptides and is key to cardiovascular homeostasis. cGMP-driven responses are terminated primarily by PDEs, but cellular efflux via multidrug resistance proteins (MRPs) might contribute. Herein, the effect of pharmacological blockade of MRPs on cGMP signalling in the heart and vasculature was investigated in vitro and in vivo., Experimental Approach: Proliferation of human coronary artery smooth muscle cells (hCASMCs), vasorelaxation of murine aorta and reductions in mean arterial BP (MABP) in response to NO donors or natriuretic peptides were determined in the absence and presence of the MRP inhibitor MK571. The ability of MRP inhibition to reverse morphological and contractile deficits in a murine model of pressure overload-induced heart failure was also explored., Key Results: MK571 attenuated hCASMC growth and enhanced the anti-proliferative effects of NO and atrial natriuretic peptide (ANP). MRP blockade caused concentration-dependent relaxations of murine aorta and augmented responses to ANP (and to a lesser extent NO). MK571 did not decrease MABP per se but enhanced the hypotensive actions of ANP and improved structural and functional indices of disease severity in experimental heart failure. These beneficial actions of MRP inhibition were associated with a greater intracellular:extracellular cGMP ratio in vitro and in vivo., Conclusions and Implications: MRP blockade promotes the cardiovascular functions of natriuretic peptides in vitro and in vivo, with more modest effects on NO. MRP inhibition may have therapeutic utility in cardiovascular diseases triggered by dysfunctional cGMP signalling, particularly those associated with altered natriuretic peptide bioactivity., Linked Articles: This article is part of a themed issue on cGMP Signalling in Cell Growth and Survival. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v179.11/issuetoc., (© 2021 The Authors. British Journal of Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.)

The objective was to evaluate the correlation between N-terminal pro-atrial natriuretic peptide (NT-proANP), corin and the severity of target organ injury in hypertensive disorders of pregnancy. A total of 78 women with hypertensive disorders of pregnancy and 49 normotensive pregnancies were enrolled. The clinical characteristics, laboratory index and echocardiogram results were collected. NT-proANP, corin, sFlt-1 and PlGF levels were measured. A receiver's operating characteristics (ROC) curve was performed to evaluate the efficacy of predicting target organ injury in the HDP group. The NT-proANP, corin, and sFlt-1/PlGF ratio were increased in the HDP group (p < .05). The area under the curve (AUC) predicted by NT-proANP and corin were larger than sFlt-1/PlGF ratio (0.779, 0.867, and 0.766, respectively). The creatinine and urine protein were significantly increased, while the estimated glomerular filtration rate (eGFR) was dramatically decreased in the HDP group (p < .05 each). The left atrial diameter (LAD), left atrial volume index (LAVI), left ventricular posterior wall thickness (LVPWT), and left ventricular septal thickness (LVST) were larger in the HDP group (p < .001 each). The NT-proANP/corin levels were positively correlated with LAD, creatinine, and urine protein, and negatively correlated with eGFR in HDP group (p < .05 each). Multiple regressions demonstrated that NT-proANP was an independent risk factor of LAD and urine protein, and corin was an independent risk factor of creatinine and eGFR in HDP group. NT-proANP and corin may be reliable biomarkers for evaluating the severity of target organ damage in the hypertensive disorders of pregnant patients., (© 2022 The Authors. The Journal of Clinical Hypertension published by Wiley Periodicals LLC.)

Human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) can model heritable arrhythmias to personalize therapies for individual patients. Although atrial fibrillation (AF) is a leading cause of cardiovascular morbidity and mortality, current platforms to generate iPSC-atrial (a) CMs are inadequate for modeling AF. We applied a combinatorial engineering approach, which integrated multiple physiological cues, including metabolic conditioning and electrical stimulation, to generate mature iPSC-aCMs. Using the patient's own atrial tissue as a gold standard benchmark, we assessed the electrophysiological, structural, metabolic, and molecular maturation of iPSC-aCMs. Unbiased transcriptomic analysis and inference from gene regulatory networks identified key gene expression pathways and transcription factors mediating atrial development and maturation. Only mature iPSC-aCMs generated from patients with heritable AF carrying the non-ion channel gene (NPPA) mutation showed enhanced expression and function of a cardiac potassium channel and revealed mitochondrial electron transport chain dysfunction. Collectively, we propose that ion channel remodeling in conjunction with metabolic defects created an electrophysiological substrate for AF. Overall, our electro-metabolic approach generated mature human iPSC-aCMs that unmasked the underlying mechanism of the first non-ion channel gene, NPPA, that causes AF. Our maturation approach will allow for the investigation of the molecular underpinnings of heritable AF and the development of personalized therapies.

Background: With aging, the human atrium invariably develops amyloid composed of ANP (atrial natriuretic peptide) and BNP (B-type natriuretic peptide). Preamyloid oligomers are the primary cytotoxic species in amyloidosis, and they accumulate in the atrium during human hypertension and a murine hypertensive model of atrial fibrillation susceptibility. We tested the hypothesis that preamyloid oligomers derived from natriuretic peptides cause cytotoxic and electrophysiological effects in atrial cells that promote arrhythmia susceptibility and that oligomer formation is enhanced for a mutant form of ANP linked to familial atrial fibrillation., Methods: Oligomerization was assessed by Western blot analysis. Bioenergic profiling was performed using the Seahorse platform. Mitochondrial dynamics were investigated with immunostaining and gene expression quantitated using quantitative reverse transcription polymerase chain reaction. Action potentials and ionic currents were recorded using patch-clamp methods and intracellular calcium measured using Fura-2., Results: Oligomer formation was markedly accelerated for mutant ANP (mutANP) compared with WT (wild type) ANP. Oligomers derived from ANP, BNP, and mutANP suppressed mitochondrial function in atrial HL-1 cardiomyocytes, associated with increased superoxide generation and reduced biogenesis, while monomers had no effects. In hypertensive mice, atrial cardiomyocytes displayed reduced action potential duration and maximal dV/dT of phase 0, with an elevated resting membrane potential, compared with normotensive mice. Similar changes were observed when atrial cells were exposed to oligomers. mutANP monomers produced similar electrophysiological effects as mutANP oligomers, likely due to accelerated oligomer formation, while ANP and BNP monomers did not. Oligomers decreased Na + current, inward rectifier K + current, and L-type Ca ++ current, while increasing sustained and transient outward K + currents, to account for these effects., Conclusions: These findings provide compelling evidence that natriuretic peptide oligomers are novel mediators of atrial arrhythmia susceptibility. Moreover, the accelerated oligomerization by mutANP supports a role for these mediators in the pathophysiology of this mutation in atrial fibrillation.

Pseudomonas aeruginosa biofilms cause chronic, antibiotic tolerant infections in wounds and lungs. Numerous recent studies demonstrate that bacteria can detect human communication compounds through specific sensor/receptor tools that modulate bacterial physiology. Consequently, interfering with these mechanisms offers an exciting opportunity to directly affect the infection process. It is shown that the human hormone Atrial Natriuretic Peptide (hANP) both prevents the formation of P. aeruginosa biofilms and strongly disperses established P. aeruginosa biofilms. This hANP action is dose-dependent with a strong effect at low nanomolar concentrations and takes effect in 30-120 min. Furthermore, although hANP has no antimicrobial effect, it acts as an antibiotic adjuvant. hANP enhances the antibiofilm action of antibiotics with diverse modes of action, allowing almost full biofilm eradication. The hANP effect requires the presence of the P. aeruginosa sensor AmiC and the AmiR antiterminator regulator, indicating a specific mode of action. These data establish the activation of the ami pathway as a potential mechanism for P. aeruginosa biofilm dispersion. hANP appears to be devoid of toxicity, does not enhance bacterial pathogenicity, and acts synergistically with antibiotics. These data show that hANP is a promising powerful antibiofilm weapon against established P. aeruginosa biofilms in chronic infections., (© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Aims: Elevated brain natriuretic peptide (BNP) and the N-terminal fragment of its pro-hormone (NT-proBNP) have become established biomarkers for heart failure and are associated with cardiovascular morbidity and mortality. Investigating sources of inter-individual heterogeneity, particularly genetic factors, could help better identify patients at risk of future cardiovascular disease. The aim of this study was to estimate the heritability of circulating NT-proBNP levels, to perform a genome-wide association study (GWAS) and gene-candidate analysis focused on NPPB-NPPA genes on these levels, and to examine their association with cardiovascular or metabolic outcomes., Methods and Results: A total of 1555 individuals from the STANISLAS study were included. The heritability of circulating NT-proBNP levels was estimated at 15%, with seven single nucleotide polymorphisms (SNPs) reaching the significant threshold in the GWAS. All above SNPs were located on the same gene cluster constituted of MTHFR, CLCN6, NPPA, NPPB, and C1orf167. NPPA gene expression was also associated with NT-proBNP levels. Moreover, six other SNPs from NPPA-NPPB genes were associated with diastolic function (lateral e' on echocardiography) and metabolic features (glycated haemoglobin)., Conclusions: The heritability of natriuretic peptides appears relatively low (15%) and mainly based on the same gene cluster constituted of MTHFR, CLCN6, NPPA, NPPB, and C1orf167. Natriuretic peptide polymorphisms are associated with natriuretic peptide levels and diastolic function. These results suggest that natriuretic peptide polymorphisms may have an impact in the early stages of cardiovascular and metabolic disease., (© 2021 The Authors. ESC Heart Failure published by John Wiley & Sons Ltd on behalf of European Society of Cardiology.)

Atrial natriuretic peptide (ANP) is secreted in response to the stretching of the atrial wall. Atrial ischemia most likely impairs the ability of atrial myocytes to produce ANP. Atrial infarction (AI) is rarely diagnosed but not infrequently associated with myocardial infarction (MI). The aim of the study was to assess the association between AI and the prognostic value of N-terminal proANP (NT-proANP) in patients with MI treated with primary percutaneous coronary intervention (PCI). We evaluated data of 100 consecutive patients. Plasma levels of NT-proANP were measured by the ELISA method. ECG recordings were interpreted to diagnose AI according to Liu's criteria. All patients were followed-up prospectively for 12 months for the manifestation of major adverse cardiovascular events (MACE), defined as unplanned coronary revascularization, stroke, reinfarction or all-cause death. AI was diagnosed in 36 patients. 14% of patients developed MACE. AI did not affect the incidence of MACE or any of its components, nor the patients' prognosis. NT-proANP revealed to be a strong predictor of death but was not associated with other adverse events. Conclusions: AI in patients with MI treated with primary PCI is not connected with their prognosis nor affects the usefulness of NT-proANP in predicting death during the 12-month follow-up.

Background: Endogenous ouabain (EO) and atrial natriuretic peptide (ANP) are important in regulation of sodium and fluid balance. There is indirect evidence that ANP may be involved in the regulation of endogenous cardenolides., Methods: H295R are human adrenocortical cells known to release EO. Cells were treated with ANP at physiologic concentrations or vehicle (0.1% DMSO), with or without guanylyl cyclase inhibitor 1,2,4 oxadiazolo[4,3-a]quinoxalin-1-one (ODQ). Cyclic guanosine monophosphate (cGMP), the intracellular second messenger of ANP, was measured by a chemiluminescent immunoassay and EO was measured by radioimmunoassay of C18 extracted samples., Results: EO secretion is inhibited by ANP treatment, with the most prolonged inhibition (90 min vs ≤ 60 min) occurring at physiologic ANP concentrations (50 pg/mL). Inhibition of guanylyl cyclase with ODQ, also reduces EO secretion. The inhibitory effects on EO release in response to cotreatment with ANP and ODQ appeared to be additive., Conclusions: ANP inhibits basal EO secretion, and it is unlikely that this is mediated through ANP-A or ANP-B receptors (the most common natriuretic peptide receptors) or their cGMP second messenger; the underlying mechanisms involved are not revealed in the current studies. The role of ANP in the control of EO synthesis and secretion in vivo requires further investigation., Competing Interests: I have read the journal’s policy and Dr. El-Mallakh is on the speakers’ bureaus of Eisai, Indivior, Intra-Cellular Therapies, Janssen, Lundbeck, Noven, Otsuka, Sunovion, and Teva. The other authors of this manuscript do not have any competing interest.

Genistein, an isoflavonoid that can inhibit protein tyrosine kinase (PTK) phosphorylation, has been shown to play pivotal roles in the signal transduction pathways of hypoxic disorders. In this study, we established a rat model of isolated beating atrium and investigated the regulator role of genistein and its downstream signaling pathways in acute hypoxia-induced atrial natriuretic peptide (ANP) secretion. Radioimmunoassay was used to detect the ANP content in the atrial perfusates. Western blot analysis was used to determine the protein level of hypoxia-inducible factor 1α (HIF-1α), and GATA 4 in the atrial tissue. The results showed that acute hypoxia substantially promoted ANP secretion, whereas this effect was partly attenuated by the PTKs inhibitor genistein (3 μM). By Western blotting analysis, we found that hypoxia-induced increase in phosphorylation of Akt and transcriptional factors, including HIF-1α, were also reversed by genistein. The perfused HIF-1α inhibitors rotenone (0.5 μM) or CAY10585 (10 μM) plus genistein significantly abolished the enhanced ANP section induced by hypoxia. Additionally, the perfused PI3K/Akt agonist insulin-like growth factor 1 (30 μM) also abolished ANP secretion induced by genistein and inhibited expression of HIF-1α. In summary, our data suggested that acute hypoxia markedly increased ANP secretion by PTKs through the phosphoinositide-3 kinase (PI3K)/HIF-1α dependent pathway.

Background: Both atrial natriuretic peptide (ANP) and vasopressin (VP) influence alcohol intake and withdrawal as well as craving and are also regulated by epigenetic factors. Disturbances in expression and promoter methylation status have been described in patients suffering from alcohol use disorder and alcohol withdrawal therapy., Objectives: In this study, we wanted to map the progression of cytosine-phosphatidyl-guanine (CpG) methylation of the respective gene promoter of ANP and VP immediately after starting alcohol withdrawal therapy when compared with healthy controls METHODS: We recruited 34 males suffering from alcohol addiction or harmful use alongside 43 healthy male controls. Blood samples for methylation analyses were drawn on days 1, 2, 3, 4, and 7-10., Results: There was no difference in mean methylation for both VP and ANP during withdrawal. There was no difference at the ANP CpG-sites after correction for multiple testing. Regarding VP, methylation was significantly higher at CpG 033, CpG 064, CpG 103, CpG 118, and CpG 194 and significantly lower at CpG 053, CpG 060, and CpG 214 when compared to healthy controls. Via in silico analysis, we identified transcription factor binding sites that could potentially influence methylation-dependent gene transcription., Conclusions: While there was no change in methylation status during withdrawal, significant differences in average methylation of specific CpG sites were observed for VP. We also identified the role of transcription factors in the context of promoter methylation as one potential mechanism that could explain the differences in VP levels between alcohol-dependent patients and healthy controls., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Background: The atrial natriuretic peptide (ANP) released from the heart regulates intravascular volume and is suspected to increase capillary permeability. Contradictory results regarding ANP and glycocalyx degradation have been reported. The aim of this study was to investigate if an infusion of ANP causes degradation of the endothelial glycocalyx., Methods: Twenty pigs, pretreated with 250 mg methylprednisolone, were randomized to receive an infusion of either ANP (50 ng/kg/min) (n = 10) or 0.9% NaCl (n = 10) during 60 min. Endothelial glycocalyx components (heparan sulphate proteoglycan and hyaluronic acid), Hct, calculated plasma volume and colloid osmotic pressure were measured from baseline to 60 min., Results: There was no difference between the control and intervention groups for heparan sulphate proteoglycan and hyaluronic acid corrected for the change in plasma volume (P = .333 and 0.197). Hct increased with 1.8 ± 2.2% in the intervention group (P = .029) with no change -0.5 ± 2.3% in the control group (P = .504). The plasma volume decreased in the intervention group with -8.4 ± 10% (P = .034) with no change in the control group 3.1 ± 12% (P = .427). Median changes in colloid osmotic pressures in the control and intervention group were -0.39 [95% CI, -1.88-0.13] and 0.9 [95% CI, 0.00-1.58], respectively (P = .012)., Conclusions: In this randomized porcine study, an ANP infusion did not cause endothelial glycocalyx degradation but decreased the plasma volume most probably due to precapillary vasodilation and increased filtration., (© 2021 The Authors. Acta Anaesthesiologica Scandinavica published by John Wiley & Sons Ltd on behalf of Acta Anaesthesiologica Scandinavica Foundation.)

Breast cancer is the 3 rd most common type of malignant tumor worldwide with high heterogeneity, frequent recurrence, and high metastasis tendency. In this study, we aimed to demonstrate the value of extracellular matrix- (ECM-) related genes in breast cancer patients. The overall expression of ECM is assessed with a novel SC3 clustering method, and patients were divided into two clusters with diverse recurrence rate. We established the Cox regression model in breast cancer patients and identified NPPA as an independent prognostic marker. The NPPA expression is downregulated in breast cancer patients, independent of the ER status, PR status, stemness score, and immune infiltrating condition. And we observed the enhanced proliferation, migration, and invasion potential of breast cancer cells after NPPA depletion. Further, we predicted the transcription modulation of NPPA with PROMO and JASPAR. And we further validated the binding of MZF1 to the -318 bp~-452 bp region of the NPPA promoter with chromatin immunoprecipitation and dual luciferase assay. Together, our study identified NPPA as a potential prognostic biomarker for breast cancer patients, whose downregulation is associated with an enhanced malignant behavior of breast cancer cells both in vivo and in vitro and identified the transcription regulation of NPPA by MZF1., Competing Interests: The authors declare that they have no competing interests with the contents of this article., (Copyright © 2021 Aijun Sun et al.)

Purpose: Left atrial appendage (LAA) closure decreases atrial natriuretic peptide (ANP) levels, which indirectly increases the risk of arrhythmogenicity. We aimed to determine the effect of a combined angiotensin receptor-neprilysin inhibitor (ARNi) on arrhythmogenicity following LAA closure in an animal model., Methods: Twenty-four rabbits were randomized into four groups: (1) control, (2) LAA closure (LAAC), (3) heart failure (HF)-LAAC, and (4) HF-LAAC with sacubitril/valsartan (+ARNi). HF models were developed in the HF-LAAC and HF-LAAC+ARNi groups. Epicardial LAA exclusion was performed in the LAAC, HF-LAAC, and HF-LAAC+ARNi groups. ANP levels were measured. An electrophysiological study was performed. The myocardium was harvested for histopathological analysis., Results: The ANP level decreased in the LAAC group (785 ± 103 pg/mL, p = 0.03), failed to increase in the HF-LAAC group (917 ± 172 pg/mL, p = 0.3), and increased in the HF-LAAC+ARNi group (1524 ± 126 pg/mL, p < 0.01) compared to that in the control group (1014 ± 56 pg/mL). The atrial effective refractory period (ERP) was prolonged in the HF-LAAC group and restored to baseline in the HF-LAAC+ARNi group. Ventricular ERP was the longest in the HF-LAAC group. The atrial fibrillation window of vulnerability (AF WOV) was elevated in the LAAC, HF-LAAC, and HF-LAAC+ARNi groups, with the latter group having lower AF WOV than the two former groups. Ventricular fibrillation (VF) inducibility was the highest in the HF-LAAC group (51 ± 5%, p < 0.001), followed by the LAAC group (30 ± 4%, p = 0.006) and the HF-LAAC+ARNi group (25 ± 5%, p = 0.11) when compared to the control group (18 ± 4%). Atrial and ventricular fibrosis were noted in all groups except the control group., Conclusion: LAA closure decreased ANP, which in turn increased AF and VF inducibility. Atrial and ventricular arrhythmogenicity was suppressed by ARNi.

Background: Mid-regional pro-atrial natriuretic peptide (MR-proANP) is a strong prognostic biomarker in cardiovascular disease but there is limited data for its use among patients undergoing dialysis., Methods: This was a cohort study of patients receiving maintenance hemodialysis from two Danish centers. Blood sampling and echocardiography were performed before and after a dialysis session. We calculated the area under the curve (AUC) for the receiver operating characteristics for diagnosing heart failure and Cox regressions for cardiovascular events and all-cause mortality., Results: Of the 306 patients, 284 (93%) had MR-proANP measurements both before and after dialysis. Median concentration was 642 pmol/L (IQR 419-858) before and 351 pmol/L (IQR 197-537) after dialysis, a mean decrease of 330 pmol/L (43%, CI 296-364, P < 0.001). MR-proANP concentration both before and after dialysis was negatively correlated to left ventricular ejection fraction with no difference in predictive ability for heart failure, AUC before and after dialysis were 0.60 (CI 0.50-0.70) and 0.61 (CI 0.51-0.71) (P = 0.40). Median follow-up was 32 months (IQR 31-33), during which 99 patients (32%) had a cardiovascular event and 110 (36%) died. A doubling of MR-proANP concentration was associated with a hazard ratio (HR) of 1.6 (CI 1.3-1.9) before and 1.7 (CI 1.4-2.0) after dialysis for mortality and a HR of 1.5 (CI 1.2-1.9) before and 1.4 (CI 1.2-1.7) after dialysis for cardiovascular events (all P < 0.001)., Conclusion: The MR-proANP concentration is elevated among patients undergoing hemodialysis and decreases during dialysis. MR-proANP concentration both before, after and intra-dialysis change strongly predicted cardiovascular events and all-cause mortality., (Copyright © 2021 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Rationale: ANP (atrial natriuretic peptide) and BNP (B-type natriuretic peptide), encoded by the clustered genes Nppa and Nppb , are important prognostic, diagnostic, and therapeutic proteins in cardiac disease. The spatiotemporal expression pattern and stress-induction of the Nppa and Nppb are tightly regulated, possibly involving their coregulation by an evolutionary conserved enhancer cluster., Objective: To explore the physiological functions of the enhancer cluster and elucidate the genomic mechanism underlying Nppa-Nppb coregulation in vivo., Methods and Results: By analyzing epigenetic data we uncovered an enhancer cluster with super enhancer characteristics upstream of Nppb . Using CRISPR/Cas9 genome editing, the enhancer cluster or parts thereof, Nppb and flanking regions or the entire genomic block spanning Nppa-Nppb , respectively, were deleted from the mouse genome. The impact on gene regulation and phenotype of the respective mouse lines was investigated by transcriptomic, epigenomic, and phenotypic analyses. The enhancer cluster was essential for prenatal and postnatal ventricular expression of Nppa and Nppb but not of any other gene. Enhancer cluster-deficient mice showed enlarged hearts before and after birth, similar to Nppa-Nppb compound knockout mice we generated. Analysis of the other deletion alleles indicated the enhancer cluster engages the promoters of Nppa and Nppb in a competitive rather than a cooperative mode, resulting in increased Nppa expression when Nppb and flanking sequences were deleted. The enhancer cluster maintained its active epigenetic state and selectivity when its target genes are absent. In enhancer cluster-deficient animals, Nppa was induced but remained low in the postmyocardial infarction border zone and in the hypertrophic ventricle, involving regulatory sequences proximal to Nppa ., Conclusions: Coordinated ventricular expression of Nppa and Nppb is controlled in a competitive manner by a shared super enhancer, which is also required to augment stress-induced expression and to prevent premature hypertrophy.

Increased myocardial autophagy has been established as an important stress-induced cardioprotective response. Three weeks after generating cardiomyocyte-specific autophagy deficiency, via inducible deletion of autophagy-related protein 7 (Atg7), we found that these mice (AKO) had increased body weight and fat mass without altered food intake. Glucose and insulin tolerance tests indicated reduced insulin sensitivity in AKO mice. Metabolic cage analysis showed reduced ambulatory activity and oxygen consumption with a trend of elevated respiratory exchange ratio in AKO mice. Direct analysis of metabolism in subcutaneous and visceral adipocytes showed increased glucose oxidation and reduced ATGL expression and HSL phosphorylation with no change in lipid synthesis or fatty acid oxidation. Importantly, we found AKO mice had reduced myocardial and circulating levels of atrial natriuretic peptide (ANP), an established mediator of myocardial-adipose cross talk. When normal ANP levels were restored to AKO mice with use of osmotic pump, the metabolic dysfunction evident in AKO mice was corrected. We conclude that cardiac autophagy deficiency alters myocardial-adipose cross talk via decreased ANP levels with adverse metabolic consequences., (© 2020 by the American Diabetes Association.)

Dysregulated inflammasome activation and interleukin (IL)-1β production are associated with several inflammatory disorders. Three different routes can lead to inflammasome activation: a canonical two-step, a non-canonical Caspase-4/5- and Gasdermin D-dependent, and an alternative Caspase-8-mediated pathway. Natriuretic Peptides (NPs), Atrial Natriuretic Peptide (ANP) and B-type Natriuretic Peptide (BNP), binding to Natriuretic Peptide Receptor-1 (NPR-1), signal by increasing cGMP (cyclic guanosine monophosphate) levels that, in turn, stimulate cGMP-dependent protein kinase-I (PKG-I). We previously demonstrated that, by counteracting inflammasome activation, NPs inhibit IL-1β secretion. Here we aimed to decipher the molecular mechanism underlying NPs effects on THP-1 cells stimulated with lipopolysaccharide (LPS) + ATP. Involvement of cGMP and PKG-I were assessed pre-treating THP-1 cells with the membrane-permeable analogue, 8-Br-cGMP, and the specific inhibitor KT-5823, respectively. We found that NPs, by activating NPR-1/cGMP/PKG-I axis, lead to phosphorylation of NLRP3 at Ser295 and to inflammasome platform disassembly. Moreover, by increasing intracellular cGMP levels and activating phosphodiesterases, NPs interfere with both Gasdermin D and Caspase-8 cleavage, indicating that they disturb non-canonical and alternative routes of inflammasome activation. These results showed that ANP and BNP anti-inflammatory and immunomodulatory actions may involve the inhibition of all the known routes of inflammasome activation. Thus, NPs might be proposed for the treatment of the plethora of diseases caused by a dysregulated inflammasome activation.

Investigations into the mixed muscle-secretory phenotype of cardiomyocytes from the atrial appendages of the heart led to the discovery that these cells produce, in a regulated manner, two polypeptide hormones - the natriuretic peptides - referred to as atrial natriuretic factor or atrial natriuretic peptide (ANP) and brain or B-type natriuretic peptide (BNP), thereby demonstrating an endocrine function for the heart. Studies on the gene encoding ANP (NPPA) initiated the field of modern research into gene regulation in the cardiovascular system. Additionally, ANP and BNP were found to be the natural ligands for cell membrane-bound guanylyl cyclase receptors that mediate the effects of natriuretic peptides through the generation of intracellular cGMP, which interacts with specific enzymes and ion channels. Natriuretic peptides have many physiological actions and participate in numerous pathophysiological processes. Important clinical entities associated with natriuretic peptide research include heart failure, obesity and systemic hypertension. Plasma levels of natriuretic peptides have proven to be powerful diagnostic and prognostic biomarkers of heart disease. Development of pharmacological agents that are based on natriuretic peptides is an area of active research, with vast potential benefits for the treatment of cardiovascular disease.

Atrial natriuretic peptide (ANP) is of major importance in the maintenance of electrolyte balance and normal blood pressure. Reduced plasma ANP levels are associated with the increased risk of cardiovascular disease. Corin is a type II transmembrane serine protease that converts the ANP precursor to mature ANP. Corin deficiency prevents ANP generation and alters electrolyte and body fluid homeostasis. Corin is synthesized as a zymogen that is proteolytically activated on the cell surface. Factors that disrupt corin folding, intracellular trafficking, cell surface expression, and zymogen activation are expected to impair corin function. To date, CORIN variants that reduce corin activity have been identified in hypertensive patients. In addition to the heart, corin expression has been detected in non-cardiac tissues, where corin and ANP participate in diverse physiological processes. In this review, we summarize the current knowledge in corin biosynthesis and post-translational modifications. We also discuss tissue-specific corin expression and function in physiology and disease., (© 2020 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.)

Gut hormones affect cardiac function and contractility. In this study, we examined whether insulin affects the cardiac atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) gene expression and release of proANP-derived peptides in pigs. Anaesthetized pigs were included in an experimental study comparing the effect of hyperinsulinemia in 15 pigs submitted to two different protocols versus 11 control pigs receiving saline infusion. Phosphorylation of Akt on Thr308 was determined by western blotting with a pAkt-Thr308 antibody. The mRNA contents of ANP and BNP were determined with real-time PCR; plasma and cardiac tissue proANP was measured with an immunoluminometric assay targeted against the mid-region of the propeptide and a processing-independent assay. Insulin stimulation increased phosphorylation of Akt Thr308 in both left atrium and left ventricle of porcine hearts (p < 0.005). No change was observed in ANP and BNP mRNA contents in the right or left atrium. BNP mRNA contents in the left ventricle, however, decreased 3-fold (p = 0.02) compared to control animals, whereas the BNP mRNA content in the right ventricle as well as ANP mRNA content in the right and left ventricle did not change following hyperinsulinemia. Moreover, the peptide contents did not change in the four cardiac chambers. Finally, proANP concentrations in plasma did not change during the insulin infusion compared to the control animals. These results suggest that insulin does not have direct effect on atrial natriuretic peptide expression but may have a role in the left ventricle., Competing Interests: Declaration of Competing Interest The authors have nothing to disclose., (Copyright © 2020. Published by Elsevier Inc.)

Atrial natriuretic peptide (ANP) is a cardiac hormone controlling blood volume and pressure in mammals. It is still unclear whether ANP controls cold-induced thermogenesis in vivo. Here, we show that acute cold exposure induces cardiac ANP secretion in mice and humans. Genetic inactivation of ANP promotes cold intolerance and suppresses half of cold-induced brown adipose tissue (BAT) activation in mice. While white adipocytes are resistant to ANP-mediated lipolysis at thermoneutral temperature in mice, cold exposure renders white adipocytes fully responsive to ANP to activate lipolysis and a thermogenic program, a physiological response that is dramatically suppressed in ANP null mice. ANP deficiency also blunts liver triglycerides and glycogen metabolism, thus impairing fuel availability for BAT thermogenesis. ANP directly increases mitochondrial uncoupling and thermogenic gene expression in human white and brown adipocytes. Together, these results indicate that ANP is a major physiological trigger of BAT thermogenesis upon cold exposure in mammals., Competing Interests: Declaration of Interests The authors declare no competing interests., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)

The intensity of accumulation and excretion of atrial natriuretic peptide in myocytes of the right atrium in rat models of renovascular hypertension and salt loading was studied by immunocytochemical analysis and transmission electron microscopy. The data suggest that high BP is not the decisive factor affecting secretion of atrial natriuretic peptide in atrial cardiomyocytes. The regulatory mechanisms of the accumulation and release of the peptide from myocyte granules can vary and depend on the pathogenesis of hypertension.

The heart is involved in the regulation of blood pressure and body fluid homeostasis. As a blood volume sensor and effector for the regulation of the volume and pressure homeostasis, the atria are the central regulator to secrete humoral messenger cardiac natriuretic hormones into the circulation. The primary action of the atria in response to the volume change in the body is to control the secretion of atrial natriuretic peptide (ANP), a member of the family of cardiac natriuretic hormones. Although all cardiac chambers are able to secrete ANP, the major source of the cardiac hormone is the atria until reactivation of the synthesis of the ventricles. In heart disease including hypertension and cardiac hypertrophy, ventricular ANP synthesis and plasma levels of ANP are increased. However, the roles of the atria for the ANP secretion are not well defined in hypertension or heart failure. Under the high concentration of plasma levels of ANP by compensatory and/or pathophysiological reactivation of the ventricular synthesis and release of ANP, with activation of the renin-angiotensin system and changes in the atrial distensibility, the roles of the atria should be reevaluated in the heart disease. The purpose of the present review is to address modulation of the atrial role in the regulation of ANP secretion and its significance in the pathological changes in hypertension and cardiac disease and to strengthen the importance of the role of the interstitial fluid dynamics of the atrial wall in the regulation of ANP secretion.

This study aimed to evaluate whether the heart is the target organ of endogenous atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in patients with heart failure (HF) with reduced ejection fraction (HFrEF).We measured the plasma levels of cyclic guanosine monophosphate (cGMP), which is a second messenger of ANP and BNP, in the aortic root (AO) and coronary sinus (CS) in 237 patients with HFrEF. Plasma levels of cGMP were significantly higher in the CS than those in the AO in 237 patients with HFrEF (10.0 ± 4.5 versus 10.5 ± 4.3 pmoL/mL, P < 0.0001) and were significantly higher in the CS than those in the AO (8.0 ± 3.6 versus 8.9 ± 3.8 pmoL/mL, P < 0.0001) in mild HF patients (New York Heart Association (NYHA) II, n = 114), but there was no difference in plasma cGMP between the AO and the CS (11.9 ± 4.4 versus 11.9 ± 4.3 pmoL/mL, NS) in severe HF patients (NYHA III-IV, n = 123). In mild HF patients, log (ANP + BNP) in the AO was an independent predictor of (CS-AO) cGMP among hemodynamics and nitrate therapy. There was a significant correlation between log [(CS-AO) ANP + (CS-AO) BNP] and (CS-AO) cGMP (r = 0.455, P < 0.0001) in mild HF patients.These findings indicate that cGMP is produced from the failing heart and that the heart is the target organ of endogenous ANP and BNP in patients with HFrEF. In severe HF patients, cGMP production may be attenuated because of the downregulation of biological receptors and/or increased cGMP degradation in the failing heart.

Chromogranin B and inositol 1,4,5-trisphosphate-associated calcium signaling leading to increased natriuretic peptide production has been described in cardiac hypertrophy. Here, we performed left anterior descending coronary artery ligation in rats as a model for systolic heart failure and examined protein and gene expression clusters in the infarcted and noninfarcted myocardium and moreover under treatment with metoprolol. We found that atrial natriuretic peptide gene transcription was significantly more elevated in the infarcted compared with the noninfarcted myocardium. Chromogranin B, which facilitates calcium release from internal stores through the inositol 1,4,5-trisphosphate receptor, was upregulated in both areas. Interestingly, angiotensin II receptor type 1 gene transcription was significantly upregulated in the infarcted and unchanged in the noninfarcted myocardium. Nuclear factor ĸappa B as a calcium-dependent transcription factor showed increased activity in the infarction zone. The β-adrenergic axis does not seem to be involved, as metoprolol treatment did not have a significant impact on any of these results. We conclude that region-specific upregulation of angiotensin II receptor type 1 is a major factor for increased atrial natriuretic peptide production in the infarcted anterior wall. This effect is most likely achieved through inositol 1,4,5-trisphosphate-mediated cytosolic calcium increase and subsequent nuclear factor ĸappa B activation, which is a known transcription factor for natriuretic peptides., (Copyright © 2019 Elsevier Inc. All rights reserved.)

It has been reported that sodium hydrosulfide (NaHS) stimulated high stretch induced-atrial natriuretic peptide (ANP) secretion via ATP sensitive potassium (K ATP ) channel. K ATP channel is activated during hypoxic condition as a compensatory mechanism. However, whether NaHS affects ANP secretion during hypoxia remains obscure. The purpose of the present study is to discover the impact of NaHS on ANP secretion during hypoxia and to unravel its signaling pathway. Isolated beating rat atria were perfused with buffer exposed to different O 2 tension (to 100% O 2 , normoxia; to 20% O 2 , hypoxia). The ANP secretion increased negatively correlated with O 2 tension. NaHS (50 μM) did not show any significant effect on low stretch induced-ANP secretion in normoxic condition but augmented low stretch induced-ANP secretion in hypoxic condition. The augmentation of NaHS-induced ANP secretion during hypoxia was blocked by the pretreatment with K ATP channel blocker (glibenclamide) and was enhanced by the pretreatment with K ATP channel activator (pinacidil). Hypoxia increased the expression of PPAR-γ protein but did not change the expression of HIF-1α protein and eNOS phosphorylation. The NaHS-induced ANP secretion during hypoxia was also blocked by the pretreatment with HIF-1α inhibitor (2-methoxy- estradiol), PPAR-γ inhibitor (GW9662) but not by NOS inhibitor (L-NAME) and endothelin receptor inhibitor (bosentan). The intravenous infusion of NaHS increased plasma ANP level in monocrotaline-treated rats but not in sham rats. These results suggest that hypoxia augmented NaHS-induced ANP secretion partly through K ATP channel, HIF-1α, and PPAR-γ pathway., (Copyright © 2019 Elsevier Inc. All rights reserved.)

The cardiac hormone atrial natriuretic peptide (ANP) is a central regulator of blood volume and a therapeutic target in hypertension and heart failure. Enhanced ANP activity in such conditions through inhibition of the degradative enzyme neprilysin has shown clinical efficacy but is complicated by consequences of simultaneous accumulation of a heterogeneous array of other hormones. Targets for specific ANP enhancement have not been available. Here, we describe a cis-acting antisense transcript (NPPA-AS1), which negatively regulates ANP expression in human cardiomyocytes. We show that NPPA-AS1 regulates ANP expression via facilitating NPPA repressor RE1-silencing transcription factor (REST) binding to its promoter, rather than forming an RNA duplex with ANP mRNA. Expression of ANP mRNA and NPPA-AS1 was increased and correlated in isolated strained human cardiomyocytes and in hearts from patients with advanced heart failure. Further, inhibition of NPPA-AS1 in vitro and in vivo resulted in increased myocardial expression of ANP, increased circulating ANP, increased renal cGMP, and lower blood pressure. The effects of NPPA-AS1 inhibition on NPPA expression in human cardiomyocytes were further marked under cell-strain conditions. Collectively, these results implicate the antisense transcript NPPA-AS1 as part of a physiologic self-regulatory ANP circuit and a viable target for specific ANP augmentation.

Purpose: The significance of the validated biomarkers of sepsis Mid-regional pro-atrial natriuretic peptide (MR-proANP) and copeptin have not been tested in a burn injury setting., Materials and Methods: 42 consecutive patients were included in a prospective observational study. Daily blood specimens collected over the initial 20 days of treatment were quantitatively analysed by immunoluminometric sandwich assay (Kryptor, BRAHMS, Berlin, Germany) for MR-proANP, copeptin and procalcitonin (PCT)., Results: In patients with absence of sepsis, copeptin levels initially increased post-burn injury and thereafter rapidly declined. In contrast, MR-proANP was only slightly elevated within the first few days. MR-proANP [199.8 (115.6; 399.5) vs 160.1 (93.7; 280.6), P < .007] and PCT [1.12 (0.32; 2.22) vs 0.32 (0.16; 0.53), P < .001] levels were significantly higher on days of sepsis. Copeptin, however, showed no significant differences [20.7 (11.8; 42.2) vs 16.8 (11.0; 30.6), P = .11]. Both, MR-proANP and PCT level increases were noted upon the first day of sepsis., Conclusion: Burn injury itself maybe associated with copeptin and to a lesser degree MR-proANP level increases. Subsequent increases in MR-proANP may be considered diagnostic for sepsis but demonstrated no advantages over PCT. The role of copeptin remains inappropriate for diagnosing sepsis after burn injury (ClinicalTrials.gov number, NCT01055587)., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Although cardiac hypertrophy is widely recognized as a risk factor that leads to cardiac dysfunction and, ultimately, heart failure, the complex mechanisms underlying cardiac hypertrophy remain incompletely characterized. The nuclear receptor peroxisome proliferator-activated receptor δ (PPARδ) is involved in the regulation of cardiac lipid metabolism. Here, we describe a novel PPARδ-dependent molecular cascade involving microRNA-29a (miR-29a) and atrial natriuretic factor (ANF), which is reactivated in cardiac hypertrophy. In addition, we identify a novel role of miR-29a, in which it has a cardioprotective function in isoproterenol hydrochloride-induced cardiac hypertrophy by targeting PPARδ and downregulating ANF. Finally, we provide evidence that miR-29a reduces the isoproterenol hydrochloride-induced cardiac hypertrophy response, thereby underlining the potential clinical relevance of miR-29a in which it may serve as a potent therapeutic target for heart hypertrophy treatment., (© 2018 Wiley Periodicals, Inc.)