Oleanolic acid modulates the renin-angiotensin system and cardiac natriuretic hormone concomitantly with volume and pressure balance in rats

Pentacyclic triterpenes, potential novel therapeutic approaches for cardiovascular diseases

Cardiovascular diseases (CVDs) involve dysfunction of the heart and blood vessels and have become major health concerns worldwide. Multiple mechanisms may be involved in the occurrence and development of CVDs. Although therapies for CVDs are constantly being developed and applied, the incidence and mortality of CVDs remain high. The roles of natural compounds in CVD treatment are being explored, providing new approaches for the treatment of CVD. Pentacyclic triterpenes are natural compounds with a basic nucleus of 30 carbon atoms, and they have been widely studied for their potential applications in the treatment of CVDs, to which various pharmacological activities contribute, including anti-inflammatory, antioxidant, and antitumor effects. This review introduces the roles of triterpenoids in the prevention and treatment of CVDs, summarizes their potential underlying mechanisms, and provides a comprehensive overview of the therapeutic potential of triterpenoids in the management of CVDs.

Unlocking the Potential of Oleanolic Acid: Integrating Pharmacological Insights and Advancements in Delivery Systems

The growing interest in oleanolic acid (OA) as a triterpenoid with remarkable health benefits prompts an emphasis on its efficient use in pharmaceutical research. OA exhibits a range of pharmacological effects, including antidiabetic, anti-inflammatory, immune-enhancing, gastroprotective, hepatoprotective, antitumor, and antiviral properties. While OA demonstrates diverse pharmacological effects, optimizing its therapeutic potential requires overcoming significant challenges. In the field of pharmaceutical research, the exploration of efficient drug delivery systems is essential to maximizing the therapeutic potential of bioactive compounds. Efficiently delivering OA faces challenges, such as poor aqueous solubility and restricted bioavailability, and to unlock its full therapeutic efficacy, novel formulation strategies are imperative. This discussion thoroughly investigates different approaches and advancements in OA drug delivery systems with the aim of enhancing the biopharmaceutical features and overall efficacy in diverse therapeutic contexts.

Molecular effects of Vitamin-D and PUFAs metabolism in skeletal muscle combating Type-II diabetes mellitus

Multiple post-receptor intracellular alterations such as impaired glucose transfer, glucose phosphorylation, decreased glucose oxidation, and glycogen production contribute to insulin resistance (IR) in skeletal muscle, manifested by diminished insulin-stimulated glucose uptake. Type-2 diabetes mellites (T2DM) has caused by IR, which is also seen in obese patients and those with metabolic syndrome. The Vitamin-D receptor (VDR) and poly unsaturated fatty acids (PUFAs) roles in skeletal muscle growth, shapes, and function for combating type-2 diabetes have been clarified throughout this research. VDR and PUFAs appears to show a variety of effects on skeletal muscle, in addition it shows a promising role on bone and mineral homeostasis. Individuals having T2DM are reported to suffer from severe muscular weakness and alterations in shape of the muscle. Several studies have investigated the effect on VDR on muscular strength and mass, which leads to Vitamin-D deficiency (VDD) in individuals, in which most commonly seen in elderly. VDR has been shown to affect skeletal cellular proliferation, intracellular calcium handling, as well as genomic activity in a variety of different ways such as muscle metabolism, insulin sensitivity, which is the major characteristic pathogenesis for IR in combating T2DM. The identified VDR gene polymorphisms are ApaI, TaqI, FokI, and BsmI that are associated with T2DM. This review collates informations on the mechanisms by which VDR activation takes place in skeletal muscles. Despite the significant breakthroughs made in recent decades, various studies show that IR affects VDR and PUFAs metabolism in skeletal muscle. Therefore, this review collates the data to show the role of VDR and PUFAs in the skeletal muscles to combat T2DM.

Herbal medicine (Oryeongsan) for fluid and sodium balance in renal cortex of spontaneously hypertensive rats

Background

Herbal medicine Oryeongsan (ORS), also known as Wulingsan in Chinesehas been used for the treatment of impaired body fluid balance. However, the mechanisms involved are not clearly defined. The purpose of the present study was to identify the actions of ORS on the renal excretory function and blood pressure (BP) and to define the mechanisms involved in association with renin-angiotensin system (RAS) and natriuretic peptide system (NPS) in spontaneously hypertensive rats (SHR), an animal model of human essential hypertension.

Methods

Changes in urine volume (UV), excretion of electrolytes including Na+ (urinary excretion of Na+ (UNaV)) were measured. RT-PCR was performed to trace the changes in expression of RAS, NPS and sodium (Na+)-hydrogen (H+) exchanger 3 (NHE3) in the renal cortex.

Results

In the SHR treated with vehicle (SHR-V) group, UV and UNaV were suppressed and the Na+ balance was maintained at the higher levels leading to an increase in BP compared to WKY-V group. These were accompanied by an increase in NHE3 expression with an accentuation of angiotensin I converting enzyme-angiotensin II type 1 (ACE-AT1) receptor and concurrent suppression of angiotensin II type 2 (AT2) receptor/ACE2-Mas receptor expression in the renal cortex. Chronic treatment with ORS increased UV and UNaV, and decreased the Na+ and water balance with a decrease in BP in the ORS-treated SHR-ORS group compared to SHR-V. These were accompanied by a decrease in NHE3 expression with a suppression of ACE-AT1 receptor and concurrent accentuation of AT2/ACE2-Mas receptor.

Conclusion

The present study shows that ORS reduced BP with a decrease in Na+ and water retention by a suppression of NHE3 expression via modulation of RAS and NPS in SHR. The present study provides pharmacological rationale for the treatment of hypertension with ORS in SHR.

The Effect and Mechanism of Oleanolic Acid in the Treatment of Metabolic Syndrome and Related Cardiovascular Diseases

Metabolic syndromes (MetS) and related cardiovascular diseases (CVDs) pose a serious threat to human health. MetS are metabolic disorders characterized by obesity, dyslipidemia, and hypertension, which increase the risk of CVDs' initiation and development. Although there are many availabile drugs for treating MetS and related CVDs, some side effects also occur. Considering the low-level side effects, many natural products have been tried to treat MetS and CVDs. A five-cyclic triterpenoid natural product, oleanolic acid (OA), has been reported to have many pharmacologic actions such as anti-hypertension, anti-hyperlipidemia, and liver protection. OA has specific advantages in the treatment of MetS and CVDs. OA achieves therapeutic effects through a variety of pathways, attracting great interest and playing a vital role in the treatment of MetS and CVDs. Consequently, in this article, we aim to review the pharmacological actions and potential mechanisms of OA in treating MetS and related CVDs.

Recent advances in medicinal chemistry of oleanolic acid derivatives

Oleanolic acid (OA), a ubiquitous pentacyclic oleanane-type triterpene isolated from edible and medicinal plants, exhibits a wide spectrum of pharmacological activities and tremendous therapeutic potential. However, the undesirable pharmacokinetic properties limit its application and development. Numerous researches on structural modifications of OA have been carried out to overcome this limitation and improve its pharmacokinetic and therapeutic properties. This review aims to compile and summarize the recent progresses in the medicinal chemistry of OA derivatives, especially on structure-activity relationship in the last few years (2010-2021). It gives insights into the rational design of bioactive derivatives from OA scaffold as promising therapeutic agents.

Anti-Obesity Effects of Aqueous Extracts of Sunbanghwalmyung-Eum in High-Fat- and High-Cholesterol-Diet-Induced Obese C57BL/6J Mice

Sunbanghwalmyung-eum (SBH) is a traditional herbal medicine that exhibits various pharmacological properties, such as antioxidant, anti-inflammatory, and anticancer activities. In this study, we investigated the systemic anti-obesity effects of an aqueous extract of SBH in the liver, adipose, and muscle tissue from high-fat and high-cholesterol diet (HFHCD)-induced obese C57BL/6J mice. After 6 weeks of an HFHCD, the mice were continuously fed HFHC with oral administration of SBH (100 mg/kg/day), Sim (simvastatin, 5 mg/kg/day, positive control), or water (HFHC only) for another 6 weeks. Our results showed that SBH attenuated the HFHCD-induced body weight gain and fat accumulation in the liver, and improved plasma lipid levels, such as those of triglycerides (TGs), blood total cholesterol (TC), and low-density lipoprotein (LDL-c). SBH and Sim inhibited the inflammation accompanied by obesity via decreasing inflammatory cytokine interleukin (IL)-1β, tumor necrosis factor α (TNFα), and monocyte chemoattractant protein 1 (MCP1). Moreover, SBH downregulated the expression of protein levels of adipogenic-related factors, including peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα), in the liver, adipose, and muscle tissue. The SBH and Sim treatment also significantly upregulated the phosphorylation of AMP-activated protein kinase α (AMPKα) in the liver and hormone-sensitive lipase (HSL) in the adipose tissue. Overall, the effects of SBH on HFHCD-induced obesity were similar to or more potent than those of simvastatin. These results indicated that SBH has great potential as a therapeutic herbal medicine for obesity.

Recent Advances Regarding the Molecular Mechanisms of Triterpenic Acids: A Review (Part I)

Triterpenic acids are phytocompounds with a widespread range of biological activities that have been the subject of numerous in vitro and in vivo studies. However, their underlying mechanisms of action in various pathologies are not completely elucidated. The current review aims to summarize the most recent literature, published in the last five years, regarding the mechanism of action of three triterpenic acids (asiatic acid, oleanolic acid, and ursolic acid), corelated with different biological activities such as anticancer, anti-inflammatory, antidiabetic, cardioprotective, neuroprotective, hepatoprotective, and antimicrobial. All three discussed compounds share several mechanisms of action, such as the targeted modulation of the PI3K/AKT, Nrf2, NF-kB, EMT, and JAK/STAT3 signaling pathways, while other mechanisms that proved to only be specific for a part of the triterpenic acids discussed, such as the modulation of Notch, Hippo, and MALAT1/miR-206/PTGS1 signaling pathway, were highlighted as well. This paper stands as the first part in our literature study on the topic, which will be followed by a second part focusing on other triterpenic acids of therapeutic value.

Amelioration of Hypertension by Oryeongsan through Improvements of Body Fluid and Sodium Balance: Roles of the Renin-Angiotensin System and Atrial Natriuretic Peptide System

Oryeongsan (Wulingsan in China and Goreisan in Japan), a formula composed of five herbal medicines, has long been used for the treatment of imbalance of the body fluid homeostasis in Asian countries. However, the mechanism by which Oryeongsan (ORS) improves the impaired body fluid and salt metabolism is not clearly defined. The present study was performed to define the role of the cardiorenal humoral system in the ORS-induced changes in blood pressure and renal function in hypertension. Experiments were performed in normotensive and two-kidney, one-clip hypertensive rats. Changes in the fluid and salt balance were measured in rats individually housed in metabolic cages. Changes in the systemic and local renin-angiotensin system (RAS) and cardiac natriuretic peptide hormone system (NPS) were evaluated. ORS water extract was administered by oral gavage (100 mg/kg daily) for 3 weeks. ORS induced diuresis and natriuresis along with an increase in glomerular filtration rate and downregulation of the Na⁺/H⁺ exchanger 3 (NHE3) and aquaporin 2 expression in the renal cortex and medulla, respectively. Furthermore, treatment with ORS significantly decreased systolic blood pressure with contraction of body sodium and water accumulation in hypertensive rats. ORS-induced changes were accompanied by modulation of the RAS and NPS, downregulation of the systemic RAS and cardiorenal expression of angiotensin-converting enzyme (ACE) and angiotensin II subtype 1 (AT₁) receptor, and upregulation of the plasma ANP concentration and cardiorenal expression of ANP, ACE2, Mas receptor, and AT₂ receptor. These findings indicate that ORS induces beneficial effects on the high blood pressure through modulation of the RAS and NPS of the cardiorenal system, suppression of the prohypertensive ACE-AT₁ receptor pathway and NHE3, accentuation of the antihypertensive ACE2-Mas axis/AT₂ receptor pathway in the kidney, suppression of the systemic RAS, and elevation of the plasma ANP levels and its synthesis in the heart. The present study provides a biological basis for the use of ORS in the treatment of impaired volume and pressure homeostasis.

Salt-Sensitive Hypertension Induces Osteoclastogenesis and Bone Resorption via Upregulation of Angiotensin II Type 1 Receptor Expression in Osteoblasts

Hypertension is a chronic-low grade inflammatory disease, which is known to be associated with increased bone loss. Excessive activity of the local renin–angiotensin system (RAS) in bone leads to increased bone resorption. As inflammatory cytokines may activate RAS components, we hypothesized that the elevated proinflammatory cytokine levels in hypertension activate bone RAS and thus lead to increased bone resorption. To investigate whether salt-sensitive hypertension (SSHTN) induces osteoclastogenesis and bone resorption, we generated a model of SSHTN in C57BL/6J mice by post-N^ω-nitro-l-arginine methyl ester hydrochloride (l-NAME) high-salt challenge. SSHTN led to the reduction of distal femur trabecular number and bone volume fraction, while trabecular separation of femoral bone showed a significant increase, with no change in cortical thickness. Histomorphometric examination showed a significant reduction in trabecular bone volume fraction with an increased number of multinucleated tartrate-resistant acid phosphatase (TRAP)-positive cells and increased osteoclast surface fraction in the trabecular distal femur of hypertensive mice. Furthermore, analysis of gene expression in bone tissue revealed that TRAP and RANKL/OPG mRNA were highly expressed in hypertensive mice. TNF-α and angiotensin II type 1 receptor (AGTR1) mRNA and protein expression were also upregulated in SSHTN mice. These observations suggested that TNF-α may have an effect on AGTR1 expression leading to osteoclast activation. However, TNF-α stimulation did not promote AGTR1 mRNA expression in osteoclast precursors in culture, while TNF-α increased AGTR1 mRNA expression in osteoblast culture by activation of downstream p38. Angiotensin II was also shown to increase TNF-α-induced RANKL/OPG mRNA expression in primary osteoblast culture and osteoclastogenesis in a TNF-α-primed osteoblast and osteoclast precursor co-culture system. In addition, local injection of lipopolysaccharide into the supracalvariae of SSHTN mice markedly promoted osteoclast and bone resorption. In conclusion, mice with SSHTN show increased osteoclastogenesis and bone resorption due mainly to increased TNF-α and partly to the upregulation of AGTR1 in osteoblasts.

Oleanolic Acid: Extraction, Characterization and Biological Activity

Oleanolic acid, a pentacyclic triterpenoid ubiquitously present in the plant kingdom, is receiving outstanding attention from the scientific community due to its biological activity against multiple diseases. Oleanolic acid is endowed with a wide range of biological activities with therapeutic potential by means of complex and multifactorial mechanisms. There is evidence suggesting that oleanolic acid might be effective against dyslipidemia, diabetes and metabolic syndrome, through enhancing insulin response, preserving the functionality and survival of β-cells and protecting against diabetes complications. In addition, several other functions have been proposed, including antiviral, anti-HIV, antibacterial, antifungal, anticarcinogenic, anti-inflammatory, hepatoprotective, gastroprotective, hypolipidemic and anti-atherosclerotic activities, as well as interfering in several stages of the development of different types of cancer; however, due to its hydrophobic nature, oleanolic acid is almost insoluble in water, which has led to a number of approaches to enhance its biopharmaceutical properties. In this scenario, the present review aimed to summarize the current knowledge and the research progress made in the last years on the extraction and characterization of oleanolic acid and its biological activities and the underlying mechanisms of action.

Preventing the onset of diabetes-induced chronic kidney disease during prediabetes: The effects of oleanolic acid on selected markers of chronic kidney disease in a diet-induced prediabetic rat model

BACKGROUND

The prevalence of prediabetes correlates with increased incidence of chronic kidney disease (CKD). This study was aimed at investigating the effects of oleanolic acid (OA) on markers associated with CKD in the prediabetic rat model.

METHODS

Prediabetes was induced by exposing male Sprague Dawley rats (150-180 g) to high-fat high- carbohydrate (HFHC) diet for 20 weeks. The prediabetic animals were further subdivided according to their treatment and treated for 12 weeks with either OA (80 mg/kg p.o) or metformin (500 mg/kg p.o) both with and without dietary intervention. 24 h fluid intake and urine output were measured every fourth week of the treatment period while the urine samples were also used for podocin quantification through PCR. The animals were then sacrificed with urine, plasma and kidneys being harvested for biochemical analysis including the measurement of aldosterone, kidney-injury-molecule-1(KIM-1), blood and urine electrolytes, estimated glomerular filtration rate (eGFR), and albumin/creatinine (Alb/Cr) ratio.

RESULTS

This study observed that OA could reduce oxidative stress in the kidney while restoring plasma aldosterone and KIM-1 as well as urine electrolytes which were found to be augmented in prediabetic animals. This also correlated with normalization of GFR and Alb/Cr ratio in the OA-treated groups in both the absence and presence of dietary intervention.

CONCLUSIONS

These findings suggest that OA can ameliorate renal complications in a prediabetic rat model. However, more research is needed for the elucidation of molecular mechanisms behind these effects.

Antihypertensive activity of oleanolic acid is mediated via downregulation of secretory phospholipase A2 and fatty acid synthase in spontaneously hypertensive rats

Oleanolic acid (OA) is reported to possess antihypertensive activity via the regulation of lipid metabolism; however, the mechanisms underlying lipid regulation by OA are yet to be fully elucidated. The aim of the present study was to evaluate the mechanisms via which OA regulates lipid metabolism in spontaneously hypertensive rats (SHRs) via ultra‑performance liquid chromatography‑quadrupole/Orbitrap‑mass spectrometry (MS)‑based lipidomics analysis. SHRs were treated with OA (1.08 mg/kg) for 4 weeks. The liver tissues were excised, homogenized in dichloromethane and centrifuged, and subsequently the supernatant layer was collected and concentrated under vacuum to dryness. The dichloromethane extract was subjected to MS analysis and database searching, and comparison of standards was performed to identify potential biomarkers. Partial least squares‑discriminant analysis performed on the liver lipidome revealed a total of 14 endogenous metabolites that were significantly changed in the SHR model group (SH group) compared with Wistar Kyoto rats [normal control (NC group)], including glycerophospholipids, sphingolipids and glycerides. Heatmaps revealed that the liver lipid profiles in the OA group were clustered more closely compared with those observed in the NC group, indicating that the antihypertensive effect of OA was mediated via regulation of liver lipid metabolites. It was observed that the protein levels of secretory phospholipase A2 (sPLA2) and fatty acid synthase (FAS) were increased in the SH group compared with the NC group. In addition, the levels of lysophosphatidylcholine and triglycerides in the liver were elevated, whereas the levels of low‑density lipoprotein cholesterol and high‑density lipoprotein cholesterol were reduced in the SH group. Upon treatment with OA, the mRNA and protein levels of PLA2 and FAS were observed to be downregulated. Collectively, the present study indicated that the antihypertensive activity of OA was mediated via downregulation of sPLA2 and FAS in SHRs, and that treatment with OA resulted in significant improvements in blood pressure and associated abnormalities in the lipid metabolites.

Modulation of Lipid Transport and Adipose Tissue Deposition by Small Lipophilic Compounds

Small lipophilic molecules present in foods of plant origin have relevant biological activities at rather low concentrations. Evidence suggests that phytosterols, carotenoids, terpenoids, and tocopherols can interact with different metabolic pathways, exerting beneficial effects against a number of metabolic diseases. These small molecules can modulate triacylglycerol absorption in the intestine and the biosynthesis of chylomicrons, the lipid carriers in the blood. Once in the bloodstream, they can impact lipoprotein clearance from blood, thereby affecting fatty acid release, incorporation into adipocytes and triglyceride reassembling and deposit. Consequently, some of these molecules can regulate pathophysiological processes associated to obesity and its related conditions, such as insulin resistance, metabolic syndrome and type-2 diabetes. The protective capacity of some lipophilic small molecules on oxidative and chemotoxic stress, can modify the expression of key genes in the adaptive cellular response, such as transcription factors, contributing to prevent the inflammatory status of adipose tissue. These small lipophilic compounds can be incorporated into diet as natural parts of food but they can also be employed to supplement other dietary and pharmacologic products as nutraceuticals, exerting protective effects against the development of metabolic diseases in which inflammation is involved. The aim of this review is to summarize the current knowledge of the influence of dietary lipophilic small biomolecules (phytosterols, carotenoids, tocopherols, and triterpenes) on lipid transport, as well as on the effects they may have on pathophysiological metabolic states, related to obesity, insulin resistance and inflammation, providing an evidence-based summary of their main beneficial effects on human health.

Recent Advances in the Knowledge of Naturally-derived Bioactive Compounds as Modulating Agents of the Renin-angiotensin-aldosterone System: Therapeutic Benefits in Cardiovascular Diseases

BACKGROUND

One of the biggest challenges to public health worldwide is to reduce the number of events and deaths related to the cardiovascular diseases. Numerous approaches have been applied to reach this goal, and drug treatment intervention has been indispensable along with an effective strategy for reducing both cardiovascular morbidity and mortality. Renin-angiotensin-aldosterone system (RAAS) blockade is currently one of the most important targets of cardiovascular drug therapy. Many studies have proven the valuable properties of naturally-derived bioactive compounds to treat cardiovascular diseases.

METHODS

The goal of this review, therefore, is to discuss the recent developments related to medicinal properties about natural compounds as modulating agents of the RAAS, which have made them an attractive alternative to be available to supplement the current therapy options.

RESULTS

Data has shown that bioactive compounds isolated from several natural products act either by inhibiting the angiotensin-converting enzyme or directly by modulating the AT1 receptors of angiotensin II, which consequently changes the entire classical axis of this system.

CONCLUSION

While there are a few evidence about the positive actions of different classes of secondary metabolites for the treatment of cardiovascular and renal diseases, data is scarce about the clinical assays established to demonstrate their value in humans.

Potential Protective Effect of Oleanolic Acid on the Components of Metabolic Syndrome: A Systematic Review

The high prevalence of obesity is a serious public health problem in today’s world. Both obesity and insulin resistance favor the development of metabolic syndrome (MetS), which is associated with a number of pathologies, especially type 2 diabetes mellitus, and cardiovascular diseases. This serious problem highlights the need to search for new natural compounds to be employed in therapeutic and preventive strategies, such as oleanolic acid (OA). This research aimed to systematically review the effects of OA on the main components of MetS as well as oxidative stress in clinical trials and experimental animal studies. Databases searched included PubMed, Medline, Web of Science, Scopus, EMBASE, Cochrane, and CINAHL from 2013 to 2019. Thus, both animal studies (n = 23) and human clinical trials (n = 1) were included in our review to assess the effects of OA formulations on parameters concerning insulin resistance and the MetS components. The methodological quality assessment was performed through using the SYRCLE’s Risk of Bias for animal studies and the Jadad scale. According to the studies in our review, OA improves blood pressure levels, hypertriglyceridemia, hyperglycemia, oxidative stress, and insulin resistance. Although there is scientific evidence that OA has beneficial effects in the prevention and treatment of MetS and insulin resistance, more experimental studies and randomized clinical trials are needed to guarantee its effectiveness.

Protective effect of triterpenes against diabetes-induced β-cell damage: An overview of in vitro and in vivo studies

Accumulative evidence shows that chronic hyperglycaemia is a major factor implicated in the development of pancreatic β-cell dysfunction in diabetic patients. Furthermore, most of these patients display impaired insulin signalling that is responsible for accelerated pancreatic β-cell damage. Indeed, prominent pathways involved in glucose metabolism such as phosphatidylinositol 3-kinase/ protein kinase B (PI3-K/AKT) and 5' AMP-activated protein kinase (AMPK) are impaired in an insulin resistant state. The impairment of this pathway is associated with over production of reactive oxygen species and pro-inflammatory factors that supersede pancreatic β-cell damage. Although several antidiabetic drugs can improve β-cell function by modulating key regulators such as PI3-K/AKT and AMPK, evidence of their β-cell regenerative and protective effect is scanty. As a result, there has been continued exploration of novel antidiabetic therapeutics with abundant antioxidant and antiinflammatory properties that are essential in protecting against β-cell damage. Such therapies include triterpenes, which have displayed robust effects to improve glycaemic tolerance, insulin secretion, and pancreatic β-cell function. This review summarises most relevant effects of various triterpenes on improving pancreatic β-cell function in both in vitro and in vivo experimental models. A special focus falls on studies reporting on the ameliorative properties of these compounds against insulin resistance, oxidative stress and inflammation, the well-known factors involved in hyperglycaemia associated tissue damage.

Atrial secretion of ANP is suppressed in renovascular hypertension: shifting of ANP secretion from atria to the left ventricle

In the present study, the change in secretion of atrial natriuretic peptide (ANP) from the atria was defined in hypertension accompanied by ventricular hypertrophy and increased synthesis of ANP. To identify the change of the secretion and mechanisms involved, experiments were performed in isolated perfused beating atria from sham-operated normotensive and renovascular hypertensive rats. Expression of ANP, natriuretic peptide receptor (NPR)-C, components of the renin-angiotensin system, and muscarinic signaling pathway was measured in cardiac tissues. Basal levels of ANP secretion and acetylcholine (ACh)- and stretch-induced activation of ANP secretion were suppressed in the atria from hypertensive compared with normotensive rats. ACh increased ANP secretion via M₂ muscarinic ACh receptor-ACh-sensitive K⁺ channel signaling. In hypertensive rats, ANP concentration increased in the left ventricle but decreased in the right ventricle. The atrial concentration of ANP was not changed in hypertensive compared with normotensive rats. ANP mRNA expression was accentuated in the left ventricle but suppressed in the other cardiac chambers in the hearts of hypertensive rats. NPR-C expression was inversely related to ANP mRNA levels. Angiotensin II type 1 receptor (AT₁R) expression was accentuated in the cardiac chambers from hypertensive rats compared with normotensive rats, whereas angiotensin II type 2 receptor, M₂ muscarinic receptor, and Kir3.4 channels were suppressed. AT₁R blockade with losartan reversed the change observed in hypertensive rats. The present findings indicate that renovascular hypertension shifts the major site of ANP secretion and synthesis from the atria to the left ventricle through modulation of the expression of ANP, NPR-C, AT₁R, and the M₂ muscarinic signaling pathway. NEW & NOTEWORTHY Renovascular hypertension suppresses the atrial secretion of ANP and shifts the major site of the regulation of ANP secretion and synthesis from atria to the hypertrophied left ventricle possibly via modulation of the expression of ANP, natriuretic peptide receptor-C, angiotensin II subtype 1 receptor, and M2 muscarinic signaling pathway.