The cardiovascular continuum and renin-angiotensin-aldosterone system blockade. J Hypertens. 2005;23:S9-17. [PMID: 15821452 DOI: 10.1097/01.hjh.0000165623.72310.dd]

Sensational site: the sodium pump ouabain-binding site and its ligands

Cardiotonic steroids (CTS), used by certain insects, toads, and rats for protection from predators, became, thanks to Withering's trailblazing 1785 monograph, the mainstay of heart failure (HF) therapy. In the 1950s and 1960s, we learned that the CTS receptor was part of the sodium pump (NKA) and that the Na+/Ca2+ exchanger was critical for the acute cardiotonic effect of digoxin- and ouabain-related CTS. This "settled" view was upended by seven revolutionary observations. First, subnanomolar ouabain sometimes stimulates NKA while higher concentrations are invariably inhibitory. Second, endogenous ouabain (EO) was discovered in the human circulation. Third, in the DIG clinical trial, digoxin only marginally improved outcomes in patients with HF. Fourth, cloning of NKA in 1985 revealed multiple NKA α and β subunit isoforms that, in the rodent, differ in their sensitivities to CTS. Fifth, the NKA is a cation pump and a hormone receptor/signal transducer. EO binding to NKA activates, in a ligand- and cell-specific manner, several protein kinase and Ca2+-dependent signaling cascades that have widespread physiological effects and can contribute to hypertension and HF pathogenesis. Sixth, all CTS are not equivalent, e.g., ouabain induces hypertension in rodents while digoxin is antihypertensinogenic ("biased signaling"). Seventh, most common rodent hypertension models require a highly ouabain-sensitive α2 NKA and the elevated blood pressure is alleviated by EO immunoneutralization. These numerous phenomena are enabled by NKA's intricate structure. We have just begun to understand the endocrine role of the endogenous ligands and the broad impact of the ouabain-binding site on physiology and pathophysiology.

Adaptive and maladaptive roles of different angiotensin receptors in the development of cardiac hypertrophy and heart failure

Angiotensin II (Ang II) is formed by the action of angiotensin-converting enzyme (ACE) in the renin-angiotensin system. This hormone is known to induce cardiac hypertrophy and heart failure and its actions are mediated by the interaction of both pro- and antihypertrophic Ang II receptors (AT1R and AT2R). Ang II is also metabolized by ACE 2 to Ang-(1-7), which elicits the activation of Mas receptors (MasR) for inducing antihypertrophic actions. Since heart failure under different pathophysiological situations is preceded by adaptive and maladaptive cardiac hypertrophy, we have reviewed the existing literature to gain some information regarding the roles of AT1R, AT2R, and MasR in both acute and chronic conditions of cardiac hypertrophy. It appears that the activation of AT1R may be involved in the development of adaptive and maladaptive cardiac hypertrophy as well as subsequent heart failure because both ACE inhibitors and AT1R antagonists exert beneficial effects. On the other hand, the activation of both AT2R and MasR may prevent the occurrence of maladaptive cardiac hypertrophy and delay the progression of heart failure, and thus therapy with different activators of these antihypertrophic receptors under chronic pathological stages may prove beneficial. Accordingly, it is suggested that a great deal of effort should be made to develop appropriate activators of both AT2R and MasR for the treatment of heart failure subjects.

Cardiovascular Consequences of Acute Kidney Injury: Treatment Options

Soon after haemodialysis was introduced into clinical practice, a high risk of cardiac death was noted in end-stage renal disease. However, only in the last decade has it become clear that any renal injury, acute or chronic, is associated with high overall and cardiovascular lethality. The need for early recognition of kidney damage in cardiovascular pathology to assess risk and develop tactics for patient management contributed to the emergence of the concept of the "cardiorenal syndrome" (CRS). CRS is a pathophysiological disorder of the heart and kidneys in which acute or chronic dysfunction of one of these organs leads to acute or chronic dysfunction of the other. The beneficial effect of ultrafiltration as a component of renal replacement therapy (RRT) is due to the elimination of hyperhydration, which ultimately affects the improvement in cardiac contractile function. This review considers the theoretical background, current status of CRS, and future potential of RRT, focusing on the benefits of ultrafiltration as a therapeutic option.

Whither digitalis? What we can still learn from cardiotonic steroids about heart failure and hypertension

Cloning of the "Na⁺ pump" (Na⁺,K⁺-ATPase or NKA) and identification of a circulating ligand, endogenous ouabain (EO), a cardiotonic steroid (CTS), triggered seminal discoveries regarding EO and its NKA receptor in cardiovascular function and the pathophysiology of heart failure (HF) and hypertension. Cardiotonic digitalis preparations were a preferred treatment for HF for two centuries, but digoxin was only marginally effective in a large clinical trial (1997). This led to diminished digoxin use. Missing from the trial, however, was any consideration that endogenous CTS might influence digitalis' efficacy. Digoxin, at therapeutic concentrations, acutely inhibits NKA but, remarkably, antagonizes ouabain's action. Prolonged treatment with ouabain, but not digoxin, causes hypertension in rodents; in this model, digoxin lowers blood pressure (BP). Furthermore, NKA-bound ouabain and digoxin modulate different protein kinase signaling pathways and have disparate long-term cardiovascular effects. Reports of "brain ouabain" led to the elucidation of a new, slow neuromodulatory pathway in the brain; locally generated EO and the α2 NKA isoform help regulate sympathetic drive to the heart and vasculature. The roles of EO and α2 NKA have been studied by EO assay, ouabain-resistant mutation of α2 NKA, and immunoneutralization of EO with ouabain-binding Fab fragments. The NKA α2 CTS binding site and its endogenous ligand are required for BP elevation in many common hypertension models and full expression of cardiac remodeling and dysfunction following pressure overload or myocardial infarction. Understanding how endogenous CTS impact hypertension and HF pathophysiology and therapy should foster reconsideration of digoxin's therapeutic utility.

Angiotensin II-Induced Signal Transduction Mechanisms for Cardiac Hypertrophy

Although acute exposure of the heart to angiotensin (Ang II) produces physiological cardiac hypertrophy and chronic exposure results in pathological hypertrophy, the signal transduction mechanisms for these effects are of complex nature. It is now evident that the hypertrophic response is mediated by the activation of Ang type 1 receptors (AT₁R), whereas the activation of Ang type 2 receptors (AT₂R) by Ang II and Mas receptors by Ang-(1-7) exerts antihypertrophic effects. Furthermore, AT₁R-induced activation of phospholipase C for stimulating protein kinase C, influx of Ca²⁺ through sarcolemmal Ca²⁺- channels, release of Ca²⁺ from the sarcoplasmic reticulum, and activation of sarcolemmal NADPH oxidase 2 for altering cardiomyocytes redox status may be involved in physiological hypertrophy. On the other hand, reduction in the expression of AT₂R and Mas receptors, the release of growth factors from fibroblasts for the occurrence of fibrosis, and the development of oxidative stress due to activation of mitochondria NADPH oxidase 4 as well as the depression of nuclear factor erythroid-2 activity for the occurrence of Ca²⁺-overload and activation of calcineurin may be involved in inducing pathological cardiac hypertrophy. These observations support the view that inhibition of AT₁R or activation of AT₂R and Mas receptors as well as depression of oxidative stress may prevent or reverse the Ang II-induced cardiac hypertrophy.

Understanding diabetes-induced cardiomyopathy from the perspective of renin angiotensin aldosterone system

Experimental and clinical evidence suggests that diabetic subjects are predisposed to a distinct cardiovascular dysfunction, known as diabetic cardiomyopathy (DCM), which could be an autonomous disease independent of concomitant micro and macrovascular disorders. DCM is one of the prominent causes of global morbidity and mortality and is on a rising trend with the increase in the prevalence of diabetes mellitus (DM). DCM is characterized by an early left ventricle diastolic dysfunction associated with the slow progression of cardiomyocyte hypertrophy leading to heart failure, which still has no effective therapy. Although the well-known "Renin Angiotensin Aldosterone System (RAAS)" inhibition is considered a gold-standard treatment in heart failure, its role in DCM is still unclear. At the cellular level of DCM, RAAS induces various secondary mechanisms, adding complications to poor prognosis and treatment of DCM. This review highlights the importance of RAAS signaling and its major secondary mechanisms involving inflammation, oxidative stress, mitochondrial dysfunction, and autophagy, their role in establishing DCM. In addition, studies lacking in the specific area of DCM are also highlighted. Therefore, understanding the complex role of RAAS in DCM may lead to the identification of better prognosis and therapeutic strategies in treating DCM.

Therapeutic targets of natural products for the management of cardiovascular symptoms of coronavirus disease 2019

The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first occurred in China in December 2019 and subsequently spread all over the world with cardiovascular, renal, and pulmonary symptoms. Therefore, recognizing and treating the cardiovascular sign and symptoms that caused by coronavirus disease 2019 (COVID-19) can be effective in reducing patient mortality. To control the COVID-19-related cardiovascular symptoms, natural products are considered one of the promising choices as complementary medicine. Scientists are struggling to discover new antiviral agents specific to this virus. In this review, the natural products for management of cardiovascular symptoms of COVID-19 are categorized into three groups: (a) natural products with an impact on angiotensin II type 1 receptor; (b) natural products that inhibit angiotensin-converting enzyme activity; and (c) natural products that mimic adenosine activity. All these natural products should undergo clinical investigations to test their efficacy, safety, and toxicity in the treatment of cardiovascular symptoms of COVID-19. This article summarizes agents with potential efficacy against COVID-19-related cardiovascular symptoms.

Approach to the cardiometabolic continuum. Narrative description

Atherosclerotic cardiovascular disease (ACVD) is the major adverse outcome in the evolution of several metabolic conditions. For around several decades, the cardiovascular continuum has been used as a fantastic tool to explain the evolution of ACVD from the onset of risk factor, to clinical outcomes, and to death. Nowadays, metabolic diseases such as obesity, prediabetes, and type2 diabetes have been increasing enough to become serious public health problems and notorious contributors to the morbidity and mortality rates due to ACVD, including arterial hypertension. Other conditions seem to increase the list, such as: physical inactivity with its metabolic cluster, sarcopenia, and non-alcoholic fatty liver disease (NAFLD). Moreover, obesity in childhood has been growing at an exponential rate so the excess of adiposity in children and adolescents will translate into an excess of cardiometabolic risk in adults. Several longitudinal studies confirm the strong association of paediatric obesity with the persistence of adult obesity, as well as the future development of cardiometabolic conditions, such as prediabetes, diabetes, obesity, increased risk of arterial hypertension, and ACVD. Therefore, it is time to conceptualise the cardiometabolic continuum as a tool of an early, wider and preventive intervention in order to reduce the morbidity and mortality due to ACVD.

An association study of C9orf3, a novel component of the renin-angiotensin system, and hypertension in diabetes

The renin-angiotensin system (RAS) is important in the onset and course of cardiovascular, kidney, and metabolic disorders. Previous reports showed that the RAS blockade protects organs and suppress the development of type 2 diabetes mellitus. A novel component of the RAS, namely, chromosome 9 open reading frame 3 (C9orf3), was recently identified, however, its effects are unclear. We evaluated whether the genetic variant of C9orf3 is associated with morbidity of hypertension among subjects with type 2 diabetes. We enrolled 382 subjects with type 2 diabetes, 222 of whom were diagnosed with hypertension. Human leukocyte genomic DNA was isolated and a genetic variant was analyzed for a C/T variant of C9orf3 (rs4385527) via PCR analysis. The relationship between the genotype and hypertension morbidity among subjects with diabetes was examined. The proportion of the respective C9orf3 genetic variants were as follows 247 CC, 119 CT, and 16 TT. The risk of hypertension was determined to be 1.58, with a 95% confidence interval of 1.11–2.27. Moreover, the p value was 0.012 for allelic comparison and for Armitage’s trend test, with the C allele identified as the risk factor. Consequently, hypertension was markedly associated with type 2 diabetes in subjects with the C9orf3 variant, exhibiting a nearly 1.6-fold increased risk. The C variant of a new component of the RAS, C9orf3 (rs4385527) might have a considerable impact on the pathogenesis of hypertension in diabetes.

Hydrogen Sulfide in Pharmacotherapy, Beyond the Hydrogen Sulfide-Donors

Hydrogen sulfide (H₂S) is one of the important biological mediators involved in physiological and pathological processes in mammals. Recently developed H₂S donors show promising effects against several pathological processes in preclinical and early clinical studies. For example, H₂S donors have been found to be effective in the prevention of gastrointestinal ulcers during anti-inflammatory treatment. Notably, there are well-established medicines used for the treatment of a variety of diseases, whose chemical structure contains sulfur moieties and may release H₂S. Hence, the therapeutic effect of these drugs may be partly the result of the release of H₂S occurring during drug metabolism and/or the effect of these drugs on the production of endogenous hydrogen sulfide. In this work, we review data regarding sulfur drugs commonly used in clinical practice that can support the hypothesis about H₂S-dependent pharmacotherapeutic effects of these drugs.

Molecular Interactions of Renin with Chikusetsusaponin IV and Momordin IIc

The paper dealt with the molecular mechanism for the binding sites and driving forces of renin with chikusetsusaponin IV and momordin IIc by means of molecular docking and free energy calculation based on the crystal structure. The result showed that renin and the saponins fit well. As shown by LigPlot + software analyzing the hydrogen bonding and hydrophobic effect between renin and the saponins, the amino acid residues such as Ser230, Tyr85, and Tyr201 form the hydrogen bonds, with S3sp, S3, and S2′ being the active pockets. In addition, there are relatively strong hydrophobic interactions of renin with saponins in S3sp, S3, S2, S1, S1′, and S2′, with Gly228, Val36, Ala229, Gln19, Met303, Gln135, Ser41, Ile137, Asp38, Arg82, and Tyr83 being the key amino acids. The dynamics reached equilibration after about 1000 ps simulation with average root-mean-square deviations of 0.222 nm and 0.217 nm. The molecular mechanics Poisson–Boltzmann surface area (MM-PBSA) yielded −1.10812 kcal/mol and −39.0587 kcal/mol total binding energy for the two complexes, respectively, which were primarily contributed by electrostatic and van der Waals interaction energies, and the binding was strongly unfavored by polar solvation energy, a further confirmation that momordin IIc has stronger hydrogen bonding and hydrophobic effect in the inhibition of renin than the chikusetsusaponin IV.

Improving obesity and blood pressure

Obesity-associated hypertension is a serious public health concern. Sympathetic nervous system (SNS) overactivity, especially in the kidneys, is an important mechanism linking obesity to hypertension. Some adipokines play important roles in elevating blood pressure (BP). Hyperinsulinemia caused by insulin resistance stimulates sodium reabsorption, enhances sodium retention, and increases circulating plasma volume. Hyperinsulinemia also stimulates both the renin-angiotensin-aldosterone system (RAAS) and the SNS, resulting in the acceleration of atherosclerosis through the hypertrophy of vascular smooth muscle cells, which contributes to increased peripheral vascular resistance. Obesity is associated with increased RAAS activity despite volume overload, as the tissue RAASs are stimulated in obese hypertensive individuals. Mineralocorticoid receptor-associated hypertension must also be considered in obese patients with resistant hypertension. Obstructive sleep apnea syndrome (OSAS) is the most common cause of secondary hypertension. Some components of the gut microbiota contribute to BP control; therefore, gut dysbiosis caused by obesity might lead to increased BP. The ratio of visceral fat to subcutaneous fat is higher in Japanese patients than in Caucasian patients, which may explain why Japanese patients are more susceptible to metabolic disorders even though they are less obese than Caucasian individuals. Obesity-associated kidney dysfunction directly increases BP, leading to further deterioration of kidney function. A bodyweight reduction of more than 3% or 5 kg significantly lowers BP. Gastrointestinal bypass surgery is an effective treatment for morbid obesity and its related metabolic disorders, including hypertension. Because both obesity and hypertension are representative lifestyle-related disorders, lifestyle modification, especially to improve obesity, should be performed first as a treatment for hypertension.

Hypertension as a Metabolic Disorder and the Novel Role of the Gut

Purpose of Review

Hypertension is related to impaired metabolic homeostasis and can be regarded as a metabolic disorder. This review presents possible mechanisms by which metabolic disorders increase blood pressure (BP) and discusses the importance of the gut as a novel modulator of BP.

Recent Findings

Obesity and high salt intake are major risk factors for hypertension. There is a hypothesis of “salt-induced obesity”; i.e., high salt intake may tie to obesity. Heightened sympathetic nervous system (SNS) activity, especially in the kidney and brain, increases BP in obese patients. Adipokines, including adiponectin and leptin, and renin-angiotensin-aldosterone system (RAAS) contribute to hypertension. Adiponectin induced by a high-salt diet may decrease sodium/glucose cotransporter (SGLT) 2 expression in the kidney, which results in reducing BP. High salt can change secretions of adipokines and RAAS-related components. Evidence has been accumulating linking the gastrointestinal tract to BP. Glucagon-like peptide-1 (GLP-1) and ghrelin decrease BP in both rodents and humans. The sweet taste receptor in enteroendocrine cells increases SGLT1 expression and stimulates sodium/glucose absorption. Roux-en-Y gastric bypass improves glycemic and BP control due to reducing the activity of SGLT1. Na/H exchanger isoform 3 (NHE3) increases BP by stimulating the intestinal absorption of sodium. Gastrin functions as an intestinal sodium taste sensor and inhibits NHE3 activity. Intestinal mineralocorticoid receptors also regulate sodium absorption and BP due to changing ENaC activity. Gastric sensing of sodium induces natriuresis, and gastric distension increases BP. Changes in the composition and function of gut microbiota contribute to hypertension. A high-salt/fat diet may disrupt the gut barrier, which results in systemic inflammation, insulin resistance, and increased BP. Gut microbiota regulates BP by secreting vasoactive hormones and short-chain fatty acids. BP-lowering effects of probiotics and antibiotics have been reported. Bariatric surgery improves metabolic disorders and hypertension due to increasing GLP-1 secretion, decreasing leptin secretion and SNS activity, and changing gut microbiome composition. Strategies targeting the gastrointestinal system may be therapeutic options for improving metabolic abnormalities and reducing BP in humans.

Summary

SNS, brain, adipocytes, RAAS, the kidney, the gastrointestinal tract, and microbiota play important roles in regulating BP. Most notably, the gut could be a novel target for treatment of hypertension as a metabolic disorder.

Clinical inertia in hypertension: a new holistic and practical concept within the cardiovascular continuum and clinical care process

Purpose: Recognition of clinical inertia is essential to improve the control of chronic diseases. Although it is very intuitive, a better interpretation of the concept of clinical inertia is lacking, likely due to its high complexity. Materials and Methods: After a review of the published articles, we propose a practical vision of inertia, contextualized within the clinical process of hypertension care. Results: This new vision enables the integration of previous terms and definitions of clinical inertia, as well as proposing specific strategies for its reduction. Conclusion: Although some concepts should be considered as 'justified inertia' or 'investigator inertia', the idea that inertia may be present throughout the continuum of care gives physicians a holistic view of the problem that is easily applicable to their clinical practice. Measures to overcome inertia are complicated because of the intrinsic complexity of the concept.

Cardiovascular risk in chronic kidney disease: what is new in the pathogenesis and treatment?

The prevalence of chronic kidney disease (CKD) has increased markedly over past decades due to the aging of the worldwide population. Despite the progress in the prevention and treatment, the cardiovascular (CV) morbidity and mortality remain high among patients with CKD. Although CKD is a progressive and irreversible condition, it is possible to slow decreasing kidney function, as well as the development and progression of associated with kidney disease comorbidities. Diabetes mellitus has become major cause of CKD worldwide. It is estimated that the prevalence of diabetes will increase from 425 million worldwide in 2017 to 629 million by 2045, substantially the percentage of diabetic nephropathy among CKD patients is set to rise markedly. The results of multicenter trials concerning novel antidiabetic drugs suggest that efficacy in reducing CV risk is independent of the improvement in glycemic control. This review discusses underlying causes of high CV risk and strategies reducing individual burden among CKD patients.

Angiotensin converting enzyme 2 and diminazene: role in cardiovascular and blood pressure regulation

PURPOSE OF REVIEW

Angiotensin converting enzyme 2 (ACE2) is an important regulator of the renin-angiotensin system through actions to degrade angiotensin II. Loss of ACE2 can contribute to the development and progression of cardiovascular disease, and experimental studies have highlighted a beneficial role for novel therapeutic approaches that activate or replenish tissue ACE2. This review focuses on experimental studies that have used the off-target effects of the antitrypanosomal agent, diminazene aceturate (DIZE) to activate ACE2.

RECENT FINDINGS

In cardiovascular disease, activation of the classical renin-angiotensin system and depletion of ACE2 leads to pathophysiological changes. One approach to activate ACE2 involves the drug DIZE, which has been shown to have beneficial effects in experimental models of hypertension, pulmonary hypertension, myocardial infarction, stroke, atherosclerosis, type 1 diabetes, and eye disease. The precise mechanism of action of DIZE to activate ACE2 remains under scrutiny.

SUMMARY

Activation of ACE2 may represent an important therapeutic approach in cardiovascular disease. To date, most studies have focused on the off-target actions of DIZE, in experimental models of disease. More research is required to determine the exact mechanism of action of DIZE and evaluate its therapeutic potential in comparison with currently available clinical interventions. There are no clinical studies of DIZE, and its side-effects, and toxicity make such studies unlikely. Hence, new methods of selectively activating or replenishing ACE2 will be needed in the future if this approach is to be used in a clinical context.

The benefit of angiotensin AT1 receptor blockers for early treatment of hypertensive patients

ESC guidelines for management of arterial hypertension allow one to choose among five classes of antihypertensive drugs indiscriminately. They are based on the principle that in the management of hypertensive patients, it is fundamental to reduce blood pressure (BP), independently of the utilized drug. However, it has been demonstrated that the renin-angiotensin system (RAS) plays a relevant role in the hypertensive-derived development and progression of organ damage. Thus, antihypertensive drugs interfering with the RAS should be preferred in preventing and reducing target organ damage. The availability of two classes of drugs, ACE-inhibitors and angiotensin AT1 receptor blockers (ARBs), both interfering with the RAS, makes the choice between them difficult. Both pharmacological strategies offer an effective BP control, and a substantial improvement of prognosis in different associated pathologies. Regarding cardiovascular prevention, ACE-inhibitors have an extensive scientific literature regarding utility in high-risk patients. Nevertheless, there is evidence to support the concept that in the early phases of organ tissue damage, the RAS is activated, but the ACE pathway producing angiotensin II is not always employed. Accordingly, ACE-inhibitors appear to be less effective, whereas ARBs have a greater beneficial action in the initial stages of atherosclerotic disease. Moreover, patients undergoing ARBs therapy show a substantially lower risk of therapy discontinuation when compared to those treated with ACE-inhibitors, because of a better tolerability. In conclusion, ACE-inhibitors should be used in patients who have already developed organ damage, but tolerate this drug well, while ARBs should be the first choice in naïve hypertensive patients without organ damage or at the initial stages of disease.

Activation and Inhibition of Sodium-Hydrogen Exchanger Is a Mechanism That Links the Pathophysiology and Treatment of Diabetes Mellitus With That of Heart Failure

The mechanisms underlying the progression of diabetes mellitus and heart failure are closely intertwined, such that worsening of one condition is frequently accompanied by worsening of the other; the degree of clinical acceleration is marked when the 2 coexist. Activation of the sodium-hydrogen exchanger in the heart and vasculature (NHE1 isoform) and the kidneys (NHE3 isoform) may serve as a common mechanism that links both disorders and may underlie their interplay. Insulin insensitivity and adipokine abnormalities (the hallmarks of type 2 diabetes mellitus) are characteristic features of heart failure; conversely, neurohormonal systems activated in heart failure (norepinephrine, angiotensin II, aldosterone, and neprilysin) impair insulin sensitivity and contribute to microvascular disease in diabetes mellitus. Each of these neurohormonal derangements may act through increased activity of both NHE1 and NHE3. Drugs used to treat diabetes mellitus may favorably affect the pathophysiological mechanisms of heart failure by inhibiting either or both NHE isoforms, and drugs used to treat heart failure may have beneficial effects on glucose tolerance and the complications of diabetes mellitus by interfering with the actions of NHE1 and NHE3. The efficacy of NHE inhibitors on the risk of cardiovascular events may be enhanced when heart failure and glucose intolerance coexist and may be attenuated when drugs with NHE inhibitory actions are given concomitantly. Therefore, the sodium-hydrogen exchanger may play a central role in the interplay of diabetes mellitus and heart failure, contribute to the physiological and clinical progression of both diseases, and explain certain drug-drug and drug-disease interactions that have been reported in large-scale randomized clinical trials.

Hydrogen Sulfide Attenuates Atherosclerosis in a Partially Ligated Carotid Artery Mouse model via Regulating Angiotensin Converting Enzyme 2 Expression

Hydrogen sulfide has been suggested to play an essential role in atherogenesis. There is a paucity of information about the association between H₂S and angiotensin converting enzyme 2 (ACE2), a novel homolog of ACE. Therefore, the aim of the study was to explore the role of H₂S in atherosclerosis with respect to ACE2 both in vitro and in vivo. Here, a murine model of acutely disturbed flow-induced atherosclerosis by left common carotid artery (LCA) partial ligation was utilized. We found that carotid partial ligation in high-fat fed apoE^−/− mice significantly inhibited endogenous H₂S synthesis in LCA. Application of NaHS, an H₂S donor considerably attenuated the severity of atherosclerosis with upregulating carotid expression of ACE2, thus converting pro-atherosclerotic angiotensin II (Ang II) to anti-atherosclerotic angiotensin 1-7 (Ang-(1-7)). The anti-atherosclerotic effect of NaHS was dramatically abolished by treatment with MLN-4760, an ACE2 inhibitor. In contrast, blockage of H₂S formation by DL-propargylglycine exacerbated the burden of atherosclerotic plaques accompanied by inhibiting carotid expression of ACE2. At the cellular level, NaHS dose-dependently promoted the expression of ACE2 and conversion from Ang II to Ang-(1-7) in unstimulated or LPS-stimulated endothelial cells, thus exerting anti-inflammatory properties. The anti-inflammatory effect of NaHS was abrogated by pretreatment with DX600, a selective ACE2 inhibitor. In conclusion, these data provide direct evidences that endogenous H₂S insufficiency exists in acute flow disturbance-induced atherosclerosis and that application of H₂S may protect against atherosclerosis via upregulating ACE2 expression in endothelial cells.

Does the pathophysiology of heart failure prime the incidence of cancer?

Both chronic heart failure (CHF) and cancer are among the most frequent causes of death in developed countries. Given that CHF activates neurohumoral factors, such as cytokines, the pathophysiology of CHF could prime the onset or progression of cancer. We consecutively enrolled 5238 patients with CHF who had been hospitalized in the Department of Cardiovascular Medicine in our institute between 2001 and 2013. We followed these patients until April 2015. We examined the cohort of patients from our hospital and compared it with a control cohort derived from the 2008 cancer database 'Monitoring of Cancer Incidence in Japan' from the National Cancer Center, Japan. The incidence of cancer in CHF patients (198 cases out of the 5238 patients) was approximately four times higher than that in control patients (2.27% vs 0.59%, P<0.0001; 95% confidence interval, 1.89-2.71). When we omitted the patients whose cancer diagnosis occurred prior to their diagnosis of CHF, we still observed a significantly higher incidence of cancer in patients with CHF than in controls. Based on our results, we suggest that there is a strong correlation between the pathophysiology of CHF and cancer. Given that CHF could prime the onset of cancers, we recommend that clinicians should be vigilant regarding cancer comorbidity in patients with CHF.

Circulating angiotensin converting enzyme 2 activity as a biomarker of silent atherosclerosis in patients with chronic kidney disease

BACKGROUND AND AIMS

Circulating Angiotensin Converting Enzyme 2 (ACE2) activity in chronic kidney disease (CKD) patients without previous history of cardiovascular disease (CVD) has been associated with classical risk factors (older age, diabetes and male gender). Furthermore, silent atherosclerosis has been described as a pathological link between CKD and CVD. We analyzed baseline ACE2 activity in non-dialysis CKD stages 3-5 (CKD3-5) patients as a biomarker of renal progression, silent atherosclerosis and CV events after 2 years of follow-up.

METHODS

Prospective study of 1458 CKD3-5 subjects without any previous CV event included in the Spanish multicenter NEFRONA study. Association between baseline circulating ACE2 activity and renal parameters, carotid/femoral echography, atheromatous disease, ankle-brachial index, intima-media thickness, need of renal replacement therapy, cardiovascular events and mortality at 24 months of follow-up were analyzed.

RESULTS

Patients with an increase in the number of territories with plaques at 24 months showed significantly higher levels of baseline ACE2 activity as compared to stable patients (29.6 (20.6-47.6)RFU/μL/h versus 35.7 (24.5-56), p < 0.001). Multivariate linear regression analysis showed that male gender, pathological ankle-brachial index and progressive silent atherosclerosis defined as an increased number of territories with plaques at 24 months were associated with increased baseline ACE2 activity. Male gender, older age, diabetes, smoking and increased baseline circulating ACE2 were independent predictors of atherosclerosis at 24 months of follow-up.

CONCLUSIONS

In CKD3-5 patients, higher circulating ACE2 activity at baseline is associated with higher risk for silent atherosclerosis, suggesting that ACE2 may serve as a biomarker to predict CV risk before CVD is established.

On the top of ARB N/L type Ca channel blocker leads to less elevation of aldosterone

The activation of the renin–angiotensin system (RAS) is one of the unfavourable characteristics of calcium channel blocker (CCB). N type calcium channel is thought to be involved in renin gene transcription and adrenal aldosterone release. Accordingly, N/L type CCB has a possibility of less elevation of plasma aldosterone concentrations (PAC) among CCBs. In a monotherapy study, we had already demonstrated that N/L type CCB leads to less activation of the RAS compared with L type CCB. The objective of this study is to substantiate the hypothesis that at the condition of additive administration on the top of an angiotensin receptor blocker (ARB), still N/L type CCB leads to less elevation of PAC compared with L type one. Subjects were 60 hypertensives administered with valsartan. As an open label study, amlodipine (L type) or cilnidipine (N/L type) were administered on the top of valsartan (ARB) in a cross-over manner. Results were as follows (valsartan+amlodipine compared with valsartan+cilnidipine): systolic blood pressure (SBP)/diastolic blood pressure (DBP) (mmHg): 132±10/76±10 compared with 131±10/77±9, P=0.95/0.48, plasma renin activity (PRA) (ng/ml·h): 2.41±2.67 compared with 2.00±1.50 P=0.20, PAC (pg/ml): 77.3±31.0 compared with 67.4±24.8, P<0.05, urinary albumin excretion (UAE) (mg/gCr): 105.9±216.1 compared with 73.9±122.2, P<0.05. Thus, PAC at cilnidipine was significantly lower than those at amlodipine in spite of the comparable BP reductions. Besides, UAE was significantly lower at cilnidipine. In conclusion, on the top of the ARB, it is suggested that cilnidipine administration might lead to less elevation of PAC and reduction in UAE compared with amlodipine.

Roles of renin-angiotensin system and Wnt pathway in aging-related phenotypes

The renin-angiotensin system (RAS) regulates diverse cellular responses and is crucial for normal organ development and function. On the other hand, RAS exerts deleterious effects promoting cardiovascular and multiple organ damage and contributes to promoting various aging-related diseases and aging-related decline in multiple organ functions. RAS blockade has been shown to prevent the progression of aging-related phenotypes and promote longevity. Wnt signaling pathway also plays a major role in the regulation of mammalian pathophysiology and is essential for organismal survival, and furthermore, it is substantially involved in the promotion of aging process. In this way, both RAS signaling and Wnt signaling have the functions of antagonistic pleiotropy during the process of growth and aging. Our recent study has demonstrated that an anti-aging effect of RAS blockade is associated with down-regulation of canonical Wnt signaling pathway, providing evidence for the hierarchical relationship between RAS signaling and Wnt signaling in promoting aging-related phenotypes. Here, we review how RAS signaling and Wnt signaling regulate the aging process and promote aging-related diseases.

Deletion of angiotensin II type 2 receptor accelerates adipogenesis in murine mesenchymal stem cells via Wnt10b/beta-catenin signaling

Recent evidence suggests that the renin-angiotensin system (RAS) has a vital role in adipocyte biology and the pathophysiology of metabolic syndrome. Obesity is the main culprit of metabolic syndrome; and mesenchymal stem cells (MSCs) have been forwarded as a major source of adipocyte generation. Previously, we reported that MSCs have a local RAS and that pharmacological blockade of angiotensin II type 2 receptor (AT2R) promotes adipogenesis in human MSCs. However, the definitive roles of AT2R and how AT2R functions in adipogenesis remains unknown. To this end, we employed AT2R-null murine MSCs to characterize how AT2R affects the differentiation of MSCs into adipocytes. Murine MSCs were isolated from AT2R-null mice and wild-type littermates, grown to confluency, and then differentiated into adipocytes. Adipogenesis was quantitated by assessing the lipid droplet accumulation. Using the lipophilic fluorescent dye, the AT2R-null cells showed significantly increased total fluorescence (261.6±49.6% vs littermate) on day 7. Oil red O staining followed by extraction of the absorbed dye and measurement of the absorbance on day 14 also exhibited significantly increased lipid droplet accumulation in the AT2R-null cells (202.7±14.1% vs littermate). We also examined the expression of adipogenic marker genes by quantitative RT-PCR. The AT2R-null group exhibited significantly increased expression of PPAR-gamma, fatty acid synthase, and adiponectin (vs littermate). We further examined the role of Wnt10b/beta-catenin signaling, which reportedly has an important inhibitory role in adipogenesis. The AT2R-null group exhibited significantly decreased Wnt10b expression accompanied by decreased beta-catenin (vs littermate). Our results thus revealed that the AT2R inhibits adipogenic differentiation in murine MSCs. Moreover, this inhibitory effect is associated with Wnt10b/beta-catenin signaling. These results provide important insights into the pathophysiology of obesity and obesity-related consequences such as metabolic syndrome, hinting at possible future therapies.

Bench-to-bedside pharmacology of adrenomedullin

The bioactive peptide adrenomedullin (AM) exerts pleiotropic actions in various organs and tissues. In the heart, AM has an inhibitory effect on ventricular remodeling, suppressing cardiomyocyte hypertrophy and the proliferation of cardiac fibroblasts. This pharmacological property was shown not only in rat models of acute myocardial infarction, but also clinically in patients with this cardiac disease. An originally characterized feature of AM was a potent vasodilatory effect, but this peptide was found to be important for vascular integrity and angiogenesis. AM-induced angiogenesis is involved in tumor growth, while AM inhibits apoptosis of some types of tumor cell. A unique pharmacological property is anti-inflammatory activity, which has been characterized in sepsis and inflammatory bowel diseases; thus, there is an ongoing clinical trial to test the efficacy of AM for patients with intractable ulcerative colitis. These activities are assumed to be mediated via the specific receptor formed by calcitonin receptor-like receptor and receptor activity-modifying protein 2 or 3, while some questions remain to be answered about the molecular mechanisms of this signal transduction system. Taking these findings together, AM is a bioactive peptide with pleiotropic effects, with potential as a therapeutic tool for a wide range of human diseases from myocardial infarction to malignant tumors or inflammatory bowel diseases.

Pleiotropic Effects of Angiotensin II Receptor Signaling in Cardiovascular Homeostasis and Aging

Most of the pathophysiological actions of angiotensin II (Ang II) are mediated through the Ang II type 1 (AT1) receptor, a member of the seven-transmembrane G protein-coupled receptor family. Essentially, AT1 receptor signaling is beneficial for organismal survival and procreation, because it is crucial for normal organ development, and blood pressure and electrolyte homeostasis. On the other hand, AT1 receptor signaling has detrimental effects, such as promoting various aging-related diseases that include cardiovascular diseases, diabetes, chronic kidney disease, dementia, osteoporosis, and cancer. Pharmacological or genetic blockade of AT1 receptor signaling in rodents has been shown to prevent the progression of aging-related phenotypes and promote longevity. In this way, AT1 receptor signaling exerts antagonistic and pleiotropic effects according to the ages and pathophysiological conditions. Here we review the pleiotropic effects of AT1 receptor signaling in cardiovascular homeostasis and aging.

Determinants of plasma renin activity: role of a human renin gene variant as a genetic factor

The plasma renin activity (PRA) is affected by a number of environmental factors. However, significant heritability has been shown for the activity. A hypothesis that a candidate regulatory single-nucleotide polymorphism, C-5312T, of human renin gene should have a significant effect on PRA was elucidated and updating of independent determinants of PRA was attempted. Cross sectional study. Outpatient study. We enrolled consecutive 810 subjects who had consulted our hospitals for lifestyle-related diseases. Genotypes were assayed with genomic DNA for C-5312T. Among the genetic variants, the difference of PRA was evaluated. Monovariate linear regression analysis was performed to test the correlation between PRA and clinical variables. Finally, stepwise multiple regression analysis was performed to evaluate the independent determinants. On comparing 2 genotype groups, CC/CT and T allele homozygote, the geometric means of PRA were 0.778 and 0.941 ng/ml/h, respectively (F = 5.992, P = 0.015). Monovariate linear regression analysis revealed that a number of variables have a significant correlation with the activity, including urinary salt excretion. A stepwise multivariate regression analysis revealed that renin C-5312T variant (TT) is one of the independent determinants of PRA. Thus, for the first time, a human renin gene variant was associated with a significant increase in PRA as a genetic factor and the independent determinants for the activity were updated including genetic factor.

Prehypertension: Underlying pathology and therapeutic options

Prehypertension (PHTN) is a global major health risk that subjects individuals to double the risk of cardiovascular disease (CVD) independent of progression to overt hypertension. Its prevalence rate varies considerably from country to country ranging between 21.9% and 52%. Many hypotheses are proposed to explain the underlying pathophysiology of PHTN. The most notable of these implicate the renin-angiotensin system (RAS) and vascular endothelium. However, other processes that involve reactive oxygen species, the inflammatory cytokines, prostglandins and C-reactive protein as well as the autonomic and central nervous systems are also suggested. Drugs affecting RAS have been shown to produce beneficial effects in prehypertensives though such was not unequivocal. On the other hand, drugs such as β-adrenoceptor blocking agents were not shown to be useful. Leading clinical guidelines suggest using dietary and lifestyle modifications as a first line interventional strategy to curb the progress of PHTN; however, other clinically respected views call for using drugs. This review provides an overview of the potential pathophysiological processes associated with PHTN, abridges current intervention strategies and suggests investigating the value of using the "Polypill" in prehypertensive subjects to ascertain its potential in delaying (or preventing) CVD associated with raised blood pressure in the presence of other risk factors.

Genetic variant of the renin-angiotensin system and prevalence of type 2 diabetes mellitus: a modest but significant effect of aldosterone synthase

Recent genome-wide association studies have identified multiple variants that confer risk of type 2 diabetes mellitus (DM). However, established associations explain only a part of the heritability. Thus, even at the genome-wide association studies era, candidate gene approach should be still useful. Recent interventional studies against the renin-angiotensin system (RAS) showed reduction in new onset of DM, implying the system is involved in the onset. We substantiated the hypothesis that genetic variants of RAS have significant association with prevalence of DM. We enrolled to the study consecutive 782 subjects who had consulted our hospitals for mainly lifestyle related diseases. They consisted of 282 (36.1 %) diabetes cases. Genotypes were assayed with genomic DNA for conventional four genes of the RAS, i.e., angiotensin converting enzyme (ACE) insertion/deletion variant, angiotensinogen (AGT) M235T variant, angiotensin II type I receptor (AT1) A1166C variant, and aldosterone synthase (CYP11B2) C-344T variant. Association between the genetic variants of the RAS and prevalence of type 2 DM was tested. A significant association of DM and CYP11B2 genotype was obtained. There was no significant association between DM and ACE, AGT and AT1 variants. A multivariate logistic regression showed that age, gender, and CYP11B2 genotype were independent factors for association to diabetes, the DM risk of CC/CT to TT being 1.40 (95 % CI 1.04-1.90, p = 0.029). Thus, it is concluded that a genetic variant of the RAS should have a modest but significant impact on the onset of type 2 diabetes mellitus.

From gene to protein-experimental and clinical studies of ACE2 in blood pressure control and arterial hypertension

Hypertension is a major risk factor for stroke, coronary events, heart and renal failure, and the renin-angiotensin system (RAS) plays a major role in its pathogenesis. Within the RAS, angiotensin converting enzyme (ACE) converts angiotensin (Ang) I into the vasoconstrictor Ang II. An “alternate” arm of the RAS now exists in which ACE2 counterbalances the effects of the classic RAS through degradation of Ang II, and generation of the vasodilator Ang 1-7. ACE2 is highly expressed in the heart, blood vessels, and kidney. The catalytically active ectodomain of ACE2 undergoes shedding, resulting in ACE2 in the circulation. The ACE2 gene maps to a quantitative trait locus on the X chromosome in three strains of genetically hypertensive rats, suggesting that ACE2 may be a candidate gene for hypertension. It is hypothesized that disruption of tissue ACE/ACE2 balance results in changes in blood pressure, with increased ACE2 expression protecting against increased blood pressure, and ACE2 deficiency contributing to hypertension. Experimental hypertension studies have measured ACE2 in either the heart or kidney and/or plasma, and have reported that deletion or inhibition of ACE2 leads to hypertension, whilst enhancing ACE2 protects against the development of hypertension, hence increasing ACE2 may be a therapeutic option for the management of high blood pressure in man. There have been relatively few studies of ACE2, either at the gene or the circulating level in patients with hypertension. Plasma ACE2 activity is low in healthy subjects, but elevated in patients with cardiovascular risk factors or cardiovascular disease. Genetic studies have investigated ACE2 gene polymorphisms with either hypertension or blood pressure, and have produced largely inconsistent findings. This review discusses the evidence regarding ACE2 in experimental hypertension models and the association between circulating ACE2 activity and ACE2 polymorphisms with blood pressure and arterial hypertension in man.

Cross talk between angiotensin-(1-7)/Mas axis and sirtuins in adipose tissue and metabolism of high-fat feed mice

Angiotensin-(1-7) and resveratrol have been described as new potential therapeutic tools on treating and preventing metabolic disorders. In the present study we aimed to evaluate the effect of an oral formulation of angiotensin-(1-7) [Ang-(1-7)] included in HPB-cyclodextrin and resveratrol (RSV), in modulation of sirtuin and renin-angiotensin system (RAS) in adipose tissue of mice treated with a high-fat diet (HFD). We observed that HFD+Ang-(1-7) and HFD+RSV groups presented marked decrease in the adipose tissue mass. Furthermore, these animals showed improved insulin-sensitivity and glucose tolerance as well as lower plasma levels of fasting glucose and lipids. The RT-PCR analysis revealed decreased expression of ACE and an increase of ACE2 [Ang-(1-7) marker] in group treated with resveratrol and also an increased expression of SIRT1 in groups that received Ang-(1-7). We showed for the first time that improved metabolic profile is associated with increased expression of GLUT4 and high expression of AMPK/FOXO1/PPAR-γ pathway in adipose-tissue. Finally, adipocyte primary cell-culture incubated with and without sirtuin and Ang-(1-7)/Mas antagonists pointed out for a cross-talking between RAS and sirtuins. We conclude that oral administration of Ang-(1-7) and RSV improved metabolic profile through a cross-modulation between RAS and Sirtuins.

Aliskiren, the future of renin–angiotensin system blockade?

The suppression of the renin-angiotensin system by angiotensin-converting enzyme inhibitors and angiotensin receptor blockers has been proven in many studies to treat hypertension and reduce cardiovascular events; however, reducing angiotensin I receptor stimulation results in the loss of the negative-feedback signal, leading to increased plasma renin activity. Numerous direct renin inhibitors were synthesized, but abandoned owing to low potency, poor bioavailability and short half-life. Aliskiren, a direct renin inhibitor of a novel structural class, inhibits the activity of the renin produced and, thus, its capacity to form angiotensin I, as measured by plasma renin activity. Aliskiren has been recently shown to be efficacious in hypertensive patients at once-daily oral dosing with favorable pharmacokinetics and the potential to improve end-organ protection.

Role of renin-angiotensin-aldosterone system in adipose tissue dysfunction

The renin-angiotensin-aldosterone system (RAAS) is known to be closely linked to the pathogenesis of insulin resistance. The angiotensin (Ang) II type 1 (AT₁) receptor mediates the major effects of Ang II in adipose tissue, and blockade of the AT₁ receptor improves insulin sensitivity, with enhanced adipocyte differentiation. In contrast, the role of angiotensin type 2 (AT₂) receptor activation in insulin sensitivity is still controversial, although AT₂ receptor functions are thought to be mutually antagonistic against those of the AT₁ receptor in the cardiovascular system. Aldosterone exerts its biological roles via the mineralocorticoid receptor (MR), and inhibition of MR signaling in adipose tissue ameliorates inflammation, with upregulation of insulin-mediated glucose transport and adipocyte differentiation. Clinical studies indicate that blockade of RAAS prevents the new onset of type 2 diabetes and improves the metabolic syndrome in diabetic patients. We here review the recent concepts of the roles of RAAS in adipose tissue.

The effect of soluble RAGE on inhibition of angiotensin II-mediated atherosclerosis in apolipoprotein E deficient mice

Background

The cross talk between RAGE and angiotensin II (AngII) activation may be important in the development of atherosclerosis. Soluble RAGE (sRAGE), a truncated soluble form of the receptor, acts as a decoy and prevents the inflammatory response mediated by RAGE activation. In this study, we sought to determine the effect of sRAGE in inhibiting AngII-induced atherosclerosis in apolipoprotein E knockout mice (Apo E KO).

Methods and Results

9 week old Apo E KO mice were infused subcutaneously with AngII (1 µg/min/kg) and saline for 4 weeks using osmotic mini-pumps. The mice were divided into 4 groups 1. saline infusion and saline injection; 2. saline infusion and sRAGE injection; 3. AngII infusion and saline injection; 4. AngII infusion and sRAGE injection. Saline or 0.5 µg, 1 µg, to 2 µg/day/mouse of sRAGE were injected intraperitoneally daily for 28 days. We showed that atherosclerotic plaque areas in the AngII-infused Apo E KO mice and markers of inflammation such as RAGE, ICAM-1, VCAM-1, and MCP-1 were increased in aorta compared to that of the Apo E KO mice. However, the treatment of 0.5 µg, 1 µg, and 2 µg of sRAGE in AngII group resulted in the dose-dependent decrease in atherosclerotic plaque area. We also demonstrated that sRAGE decreased RAGE expression level as well as inflammatory cytokines and cell adhesion molecules in AngII or HMGB1 treated-rat aorta vascular smooth muscle cells.

Conclusion

The results demonstrated that partical blockade of RAGE activation by sRAGE prevent AngII -induced atherosclerosis. Therefore these results suggested that first, RAGE activation may be important in mediating AngII-induced atherogenesis, and second, AngII activation is a major pathway in the development of atherosclerosis. Taken together, results from this study may provide the basis for future anti- atherosclerotic drug development mediated through RAGE activation.

Pharmacokinetics, Safety, and Tolerability of the Oral Renin Inhibitor Aliskiren in Patients With Hepatic Impairment

Aliskiren is the first in a new class of orally active, direct renin inhibitors for the treatment of hypertension. This open-label, nonrandomized, single-center, parallel-group study compared the pharmacokinetics and safety of a single 300-mg oral dose of aliskiren in patients with mild, moderate, or severe hepatic impairment to that in healthy subjects. When pooled across subgroups, there were no significant differences between patients with hepatic impairment and healthy subjects in aliskiren AUC(0-infinity) (ratio of geometric means, 1.12; 90% confidence interval, 0.85, 1.48) or Cmax (mean ratio, 1.19; 90% confidence interval, 0.84, 1.68), and there was no correlation between severity of hepatic impairment and either AUC(0-infinity) or Cmax. Aliskiren was well tolerated by healthy subjects and patients with hepatic impairment. In conclusion, hepatic impairment has no significant effect on the pharmacokinetics of aliskiren following single-dose administration, and dosage adjustment is unlikely to be needed in patients with liver disease.

Angioprotection role in arterial hypertension treatment: focus on olmesartan

The paper discusses the role of organoprotection in arterial hypertension treatment. The results of international studies on effectiveness of olmesartan, a modern angiotensin II receptor antagonist, are presented. The available evidence confirms not only a strong antihypertensive effect of olmesartan, but also its vasoprotective characteristics. Olmesartan reduces vascular inflammation, facilitates the regression of vascular wall hypertrophy, and reduces the volume of atherosclerotic plaque. In Russia, the medication Cardosal® has become available relatively recently. Due to the extensive evidence base confirming its antihypertensive and vasoprotective effects, this medication appears promising for various clinical groups of Russian hypertensives. Not only adequate blood pressure control, but also effective reduction in the risk of cardiovascular complications could be expected.

Preventing cardiovascular events with angiotensin II receptor blockers: a closer look at telmisartan and valsartan

Angiotensin II receptor blockers (ARBs) inhibit the renin-angiotensin system. As a result, these agents provide beneficial effects in terms of cardiovascular (CV) and renal protection, independent of their blood pressure-lowering effects. Telmisartan and valsartan are the most intensively studied ARBs for the effects on CV outcomes. Randomized clinical trials assessing morbidity and mortality end points have included a range of patient types, including those with hypertension, hypertension with Type 2 diabetes, high CV risk without hypertension, ischemic heart disease, stroke and heart failure. Few head-to-head comparisons between telmisartan and valsartan have been performed. However, some blood pressure-independent properties of these two ARBs can be scrutinized from separate studies in the available literature.

The ACE2 gene: its potential as a functional candidate for cardiovascular disease

The RAS (renin–angiotensin system) plays an important role in the pathophysiology of CVD (cardiovascular disease), and RAS blockade is an important therapeutic strategy in the management of CVD. A new counterbalancing arm of the RAS is now known to exist in which ACE (angiotensin-converting enzyme) 2 degrades Ang (angiotensin) II, the main effector of the classic RAS, and generates Ang-(1–7). Altered ACE2 expression is associated with cardiac and vascular disease in experimental models of CVD, and ACE2 is increased in failing human hearts and atherosclerotic vessels. In man, circulating ACE2 activity increases with coronary heart disease, as well as heart failure, and a large proportion of the variation in plasma ACE2 levels has been attributed to hereditary factors. The ACE2 gene maps to chromosome Xp22 and this paper reviews the evidence associating ACE2 gene variation with CVD and considers clues to potential functional ACE2 variants that may alter gene expression or transcriptional activity. Studies to date have investigated ACE2 gene associations in hypertension, left ventricular hypertrophy and coronary artery disease, but the results have been inconsistent. The discrepancies may reflect the sample size of the studies, the gender or ethnicity of subjects, the cardiovascular phenotype or the ACE2 SNP investigated. The frequent observation of apparent sex-dependence might be of special importance, if confirmed. As yet, there are no studies to concurrently assess ACE2 gene polymorphisms and circulating ACE2 activity. Large-scale carefully conducted clinical studies are urgently needed to clarify more precisely the potential role of ACE2 in the CVD continuum.

Effects of kimchi supplementation on blood pressure and cardiac hypertrophy with varying sodium content in spontaneously hypertensive rats

We tested the effects of dietary intake of freeze-dried Korean traditional fermented cabbage (generally known as kimchi) with varying amounts of sodium on blood pressure and cardiac hypertrophy in spontaneously hypertensive rats (SHRs). Wistar-Kyoto rats (WKY), as a control group, received a regular AIN-76 diet, and the SHRs were divided into four groups. The SHR group was fed a regular diet without kimchi supplementation, the SHR-L group was fed the regular diet supplemented with low sodium kimchi containing 1.4% salt by wet weight, which was provided in a freeze-dried form, the SHR-M group was supplemented with medium levels of sodium kimchi containing 2.4% salt, and the SHR-H group was supplemented with high sodium kimchi containing 3.0% salt. Blood pressure was measured over 6 weeks, and cardiac hypertrophy was examined by measuring heart and left ventricle weights and cardiac histology. SHRs showed higher blood pressure compared to that in WKY rats, which was further elevated by consuming high sodium containing kimchi but was not influenced by supplementing with low sodium kimchi. None of the SHR groups showed significant differences in cardiac and left ventricular mass or cardiomyocyte size. Levels of serum biochemical parameters, including blood urea nitrogen, creatinine, glutamic-oxaloacetic transaminase, glutamic-pyruvic transaminase, sodium, and potassium were not different among the groups. Elevations in serum levels of aldosterone in SHR rats decreased in the low sodium kimchi group. These results suggest that consuming low sodium kimchi may not adversely affect blood pressure and cardiac function even under a hypertensive condition.

Renin-angiotensin system blockade and reduction of cardiovascular risk: future perspectives

Treatment with renin-angiotensin system blockers (angiotensin-converting enzyme inhibitors and angiotensin receptor blockers) has shown clear benefits in distinct stages of cardiovascular disease. These treatments lower blood pressure and prevent the appearance of markers of subclinical disease (such as microalbuminuria), reduce cardiovascular and renal events in patients with subclinical lesions, and prolong survival in patients with clinical disease or organ dysfunction. Despite this unquestionable benefit, the residual risk in patients receiving these treatments often continues to be high and, consequently, strategies to reduce such risk are required. The present article reviews options that may help to reduce cardiovascular disease in such patients. They include efforts of primary prevention in healthy individuals, stricter therapeutic goals, comprehensive risk control, a more complete blocking of the renin-angiotensin system and the use of combinations of drugs with synergistic protective mechanisms.

Novel cardiac-specific biomarkers and the cardiovascular continuum

The concept of the cardiovascular continuum, introduced during the early 1990s, created a holistic view of the chain of events connecting cardiovascular-related risk factors with the progressive development of pathological-related tissue remodelling and ultimately, heart failure and death. Understanding of the tissue-specific changes, and new technologies developed over the last 25-30 years, enabled tissue remodelling events to be monitored in vivo and cardiovascular disease to be diagnosed more reliably than before. The tangible product of this evolution was the introduction of a number of biochemical markers such as troponin I and T, which are now commonly used in clinics to measure myocardial damage. However, biomarkers that can detect specific earlier stages of the cardiovascular continuum have yet to be generated and utilised. The majority of the existing markers are useful only in the end stages of the disease where few successful intervention options exist. Since a large number of patients experience a transient underlying developing pathology long before the signs or symptoms of cardiovascular disease become apparent, the requirement for new markers that can describe the early tissue-specific, matrix remodelling process which ultimately leads to disease is evident. This review highlights the importance of relating cardiac biochemical markers with specific time points along the cardiovascular continuum, especially during the early transient phase of pathology progression where none of the existing markers aid diagnosis.