angiotensin-i and Heart-Failure

Cardiac remodeling (cardiac hypertrophy and fibrosis) is a hallmark of heart failure (HF). It can be induced by the abnormal elevation of several endogenous factors including angiotensin II (Ang II), which is generated from its precursor angiotensin I (Ang I) by the action of angiotensin-converting enzyme. The inhibition of this enzyme or the blockade of the Ang II receptors demonstrated a high clinical value against the progression of HF. Ang I and Ang II may also be converted into angiotensin 1-7 (Ang 1-7) and angiotensin 1-9 (Ang 1-9), respectively, by the action of angiotensin-converting enzyme 2. Both derivatives demonstrated a promising anticardiac remodeling activity especially against the detrimental effects of Ang II. This manuscript thoroughly reviews the available in vitro and in vivo data on Ang 1-7 and Ang 1-9 in the context of the treatment of HF and discusses the associated molecular mechanisms and the trials to clinically utilize Ang 1-7 mimetics for the treatment of that disease.

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme 2; Animals; Cardiovascular Agents; Heart Failure; Humans; Molecular Mimicry; Molecular Targeted Therapy; Peptide Fragments; Peptidyl-Dipeptidase A; Signal Transduction; Treatment Outcome

Heart failure (HF) is a common cause of death and disability and a major economic burden in industrialized nations. Heart disease remains the leading cause of death in North America, with ischemic and hypertensive heart disease as the leading cause of HF. Various basic and clinical studies have established the role of an activated renin-angiotensin (Ang) system and Ang II generation in the progression of HF. Inhibition of an activated renin-Ang system using Ang-converting enzyme inhibitors, Ang II type 1 receptor blockers, and mineralocorticoid receptors antagonists have shown clinical benefits in patients with HF, although, largely limited to HF with reduced ejection fraction (HF-rEF). In contrast, there is no approved pharmacotherapy for HF with preserved ejection fraction (HF-pEF). Ang-converting enzyme (ACE) 2 (ACE2) is a homolog of ACE, which, being a monocarboxypeptidase converts Ang II into Ang 1-7 and is downregulated in HF. Various preclinical studies have shown a potent cardioprotective role of ACE2/Ang 1-7 axis in HF, which counter-regulates the ACE/Ang II/Ang II type 1 receptor axis. Importantly, ACE2 and Ang 1-7 show substantial benefit in preclinical models of HF-pEF and HF-rEF. Improvement in endothelial dysfunction, suppression of tissue inflammation and myocardial fibrosis, correction of metabolic dysfunction, and reversal of pathological hypertrophy are the key beneficial effects seen when ACE2 or Ang 1-7 action are enhanced. Clinical benefit of recombinant human ACE2 and Ang 1-7 need to be evaluated in patients with HF-rEF and HF-pEF.

Topics: Angiotensin I; Heart Failure; Humans; Peptide Fragments; Peptidyl-Dipeptidase A; Recombinant Proteins; Renin-Angiotensin System; Vasodilator Agents

Heart failure (HF) remains the most common cause of death and disability, and a major economic burden, in industrialized nations. Physiological, pharmacological, and clinical studies have demonstrated that activation of the renin-angiotensin system is a key mediator of HF progression. Angiotensin-converting enzyme 2 (ACE2), a homolog of ACE, is a monocarboxypeptidase that converts angiotensin II into angiotensin 1-7 (Ang 1-7) which, by virtue of its actions on the Mas receptor, opposes the molecular and cellular effects of angiotensin II. ACE2 is widely expressed in cardiomyocytes, cardiofibroblasts, and coronary endothelial cells. Recent preclinical translational studies confirmed a critical counter-regulatory role of ACE2/Ang 1-7 axis on the activated renin-angiotensin system that results in HF with preserved ejection fraction. Although loss of ACE2 enhances susceptibility to HF, increasing ACE2 level prevents and reverses the HF phenotype. ACE2 and Ang 1-7 have emerged as a key protective pathway against HF with reduced and preserved ejection fraction. Recombinant human ACE2 has been tested in phase I and II clinical trials without adverse effects while lowering and increasing plasma angiotensin II and Ang 1-7 levels, respectively. This review discusses the transcriptional and post-transcriptional regulation of ACE2 and the role of the ACE2/Ang 1-7 axis in cardiac physiology and in the pathophysiology of HF. The pharmacological and therapeutic potential of enhancing ACE2/Ang 1-7 action as a novel therapy for HF is highlighted.

Topics: Angiotensin I; Angiotensin-Converting Enzyme 2; Animals; Heart Failure; Humans; Peptide Fragments; Peptidyl-Dipeptidase A; Renin-Angiotensin System; Signal Transduction

The renin-angiotensin system (RAS) plays a major role in the pathophysiology of cardiovascular disorders. Angiotensin II (Ang-II), the final product of this pathway, is known for its vasoconstrictive and proliferative effects. Angiotensin-converting enzyme 2 (ACE2), a newly discovered homolog of ACE, plays a key role as the central negative regulator of the RAS. It diverts the generation of vasoactive Ang-II into the vasodilatory and growth inhibiting peptide angiotensin(1-7) [Ang(1-7)], thereby providing counter-regulatory responses to neurohormonal activation. There is substantial experimental evidence evaluating the role of ACE2/Ang(1-7) in hypertension, heart failure, and atherosclerosis. In this review, we aim to focus on the conceptual facts of the ACE2-Ang(1-7) axis with regards to clinical implications and therapeutic targets in cardiovascular disorders, with emphasis on the potential therapeutic role in cardiovascular diseases.

Topics: Angiotensin I; Angiotensin-Converting Enzyme 2; Cardiovascular Agents; Heart Failure; Humans; Hypertension; Molecular Targeted Therapy; Peptide Fragments; Peptidyl-Dipeptidase A; Renin-Angiotensin System; Ventricular Remodeling

Chronic RAS (renin-angiotensin system) activation by both AngII (angiotensin II) and aldosterone leads to hypertension and perpetuates a cascade of pro-hypertrophic, pro-inflammatory, pro-thrombotic and atherogenic effects associated with cardiovascular damage. In 2000, a new pathway consisting of ACE2 (angiotensin-converting enzyme2), Ang-(1-9) [angiotensin-(1-9)], Ang-(1-7) [angiotensin-(1-7)] and the Mas receptor was discovered. Activation of this novel pathway stimulates vasodilation, anti-hypertrophy and anti-hyperplasia. For some time, studies have focused mainly on ACE2, Ang-(1-7) and the Mas receptor, and their biological properties that counterbalance the ACE/AngII/AT1R (angiotensin type 1 receptor) axis. No previous information about Ang-(1-9) suggested that this peptide had biological properties. However, recent data suggest that Ang-(1-9) protects the heart and blood vessels (and possibly the kidney) from adverse cardiovascular remodelling in patients with hypertension and/or heart failure. These beneficial effects are not modified by the Mas receptor antagonist A779 [an Ang-(1-7) receptor blocker], but they are abolished by the AT2R (angiotensin type 2 receptor) antagonist PD123319. Current information suggests that the beneficial effects of Ang-(1-9) are mediated via the AT2R. In the present review, we summarize the biological effects of the novel vasoactive peptide Ang-(1-9), providing new evidence of its cardiovascular-protective activity. We also discuss the potential mechanism by which this peptide prevents and ameliorates the cardiovascular damage induced by RAS activation.

Topics: Angiotensin I; Animals; Cardiovascular System; Heart Failure; Humans; Hypertension; Peptide Fragments; Receptor, Angiotensin, Type 2; Renin-Angiotensin System

The renin-angiotensin system (RAS) plays an important role in the normal control of cardiovascular and renal function in the healthy state and is a contributing factor in the development and progression of various types of cardiovascular diseases (CVD), including hypertension, diabetes, and heart failure.. Evidence suggests that a balance between activation of the ACE/Ang II/AT1 receptor axis and the ACE2/Ang-(1-7)/Mas receptor axis is important for the function of the heart, kidney, and autonomic nervous system control of the circulation in the normal healthy state. An imbalance in these opposing pathways toward the ACE/Ang II/AT1 receptor axis is associated with CVD. The key component of this imbalance with respect to neural control of the circulation is the negative interaction between oxidative and NO• mechanisms, which leads to enhanced sympathetic tone and activation in disease conditions such as hypertension and heart failure.. The key mechanisms that disrupt normal regulation of Ang II and Ang-(1-7) signaling and promote pathogenesis of CVD at all organ levels remain poorly understood. The reciprocal relation between ACE and ACE2 expression and function suggests they are controlled interdependently at pre- and post-translational levels. Insights from neural studies suggest that an interaction between oxidative and nitrosative pathways may be key.. The role of redox mechanisms in the control of expression and activity of RAS enzymes and Ang receptors may provide important insight into the function of local tissue RAS in health and disease.

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme 2; Cardiovascular Diseases; Heart Failure; Humans; Nitric Oxide; Peptide Fragments; Peptides; Peptidyl-Dipeptidase A; Receptor, Angiotensin, Type 1; Renin-Angiotensin System

A novel angiotensin-converting enzyme (ACE) homolog, named ACE2, is a monocarboxypeptidase which metabolizes several peptides. ACE2 degrades Angiotensin (Ang) II, a peptide with vasoconstrictive/proliferative effects, to generate Ang-(1-7), which acting through its receptor Mas exerts vasodilatory/anti-proliferative actions. In addition, as ACE2 is a multifunctional enzyme and its actions on other vasoactive peptides can also contribute to its vasoactive effects including the apelin-13 and apelin-17 peptides. The discovery of ACE2 corroborates the establishment of two counter-regulatory arms within the renin-angiotensin system. The first one is formed by the classical pathway involving the ACE-Ang II-AT(1) receptor axis and the second arm is constituted by the ACE2-Ang 1-7/Mas receptor axis. Loss of ACE2 enhances the adverse pathological remodeling susceptibility to pressure-overload and myocardial infarction. ACE2 is also a negative regulator of Ang II-induced myocardial hypertrophy, fibrosis, and diastolic dysfunction. The ACE2-Ang 1-7/Mas axis may represent new possibilities for developing novel therapeutic strategies for the treatment of hypertension and cardiovascular diseases. In this review, we will summarize the biochemical and pathophysiological aspects of ACE2 with a focus on its role in diastolic and systolic heart failure.

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme 2; Heart Failure; Humans; Hypertension; Peptide Fragments; Peptidyl-Dipeptidase A; Renin-Angiotensin System; Signal Transduction

Fibroblasts play a pivotal role in cardiac remodeling and the development of heart failure through the deposition of extra-cellular matrix (ECM) proteins and also by affecting cardiomyocyte growth and function. The renin-angiotensin system (RAS) is a key regulator of the cardiovascular system in health and disease and many of its effects involve cardiac fibroblasts. Levels of angiotensin II (Ang II), the main effector molecule of the RAS, are elevated in the failing heart and there is a substantial body of evidence indicating that this peptide contributes to changes in cardiac structure and function which ultimately lead to progressive worsening in heart failure. A pathway involving angiotensin converting enzyme 2 (ACE2) has the capacity to break down Ang II while generating angiotensin-(1-7) (Ang-(1-7)), a heptapeptide, which in contrast to Ang II, has cardioprotective and anti-remodeling effects. Many Ang-(1-7) actions involve cardiac fibroblasts and there is information indicating that it reduces collagen production and also may protect against cardiac hypertrophy. This report describes the effects of ACE2 and Ang-(1-7) that appear to be relevant in cardiac remodeling and heart failure and explores potential therapeutic strategies designed to increase ACE2 activity and Ang-(1-7) levels to treat these conditions. This article is part of a special issue entitled ''Key Signaling Molecules in Hypertrophy and Heart Failure.''

Topics: Angiotensin I; Angiotensin-Converting Enzyme 2; Angiotensin-Converting Enzyme Inhibitors; Animals; Gene Expression; Heart; Heart Failure; Humans; Molecular Targeted Therapy; Myocardium; Myofibroblasts; Organ Specificity; Peptide Fragments; Peptidyl-Dipeptidase A; Renin-Angiotensin System; Translational Research, Biomedical; Ventricular Remodeling

Angiotensin-converting enzyme 2 (ACE2) is a monocarboxypeptidase that metabolizes several peptides, including the degradation of angiotensin (Ang) II, a peptide with vasoconstrictive/proliferative effects, to generate Ang 1-7, which exerts vasodilatory/antiproliferative actions by acting through its receptor Mas. ACE2 is a multifunctional enzyme, and its actions on other vasoactive peptides, including the apelin-13 and apelin-17 peptides, also can contribute to its cardiovascular effects. The classical pathway of the renin-angiotensin system involving the ACE-Ang II-Ang II type-1 receptor axis is antagonized by the second arm constituted by the ACE2/Ang 1-7/Mas receptor axis. Loss of ACE2 enhances the adverse pathological remodeling susceptibility to pressure overload and myocardial infarction. Human recombinant ACE2 also is a negative regulator of Ang II-induced myocardial hypertrophy, fibrosis, and diastolic dysfunction and suppresses pressure overload-induced heart failure. Due to its characteristics, the ACE2/Ang 1-7/Mas axis may represent new possibilities for developing novel therapeutic strategies for the treatment of hypertension and heart failure. This review summarizes the beneficial effects of ACE2 in heart disease and the potential use of human recombinant ACE2 as a novel therapy for heart failure.

Topics: Angiotensin I; Angiotensin-Converting Enzyme 2; Angiotensin-Converting Enzyme Inhibitors; Diastole; Heart Failure; Humans; Peptide Fragments; Peptidyl-Dipeptidase A; Recombinant Proteins; Renin-Angiotensin System; Signal Transduction

Despite considerable therapeutic advances over recent years, chronic heart failure remains associated with significant morbidity and mortality. Further improvements in the treatment of this syndrome are therefore needed and this will require advances in the understanding of its underlying pathophysiology. This article reviews the literature regarding recently identified neurohormonal pathways that are declaring themselves as potential therapeutic targets in chronic heart failure.

Topics: Angiotensin I; Angiotensin-Converting Enzyme 2; Animals; Antihypertensive Agents; Cardiovascular Physiological Phenomena; Heart Failure; Humans; Intercellular Signaling Peptides and Proteins; Myocardium; Peptide Fragments; Peptidyl-Dipeptidase A; Prorenin Receptor; Receptors, Cell Surface; Relaxin; Renin; Urocortins

Angiotensin type 1 receptors (AT(1)Rs) play a critical role in a variety of physiological functions and pathophysiological states. They have been strongly implicated in the modulation of sympathetic outflow in the brain. An understanding of the mechanisms by which AT(1)Rs are regulated in a variety of disease states that are characterized by sympathoexcitation is pivotal in development of new strategies for the treatment of these disorders. This review concentrates on several aspects of AT(1)R regulation in the setting of chronic heart failure (CHF). There is now good evidence that AT(1)R expression in neurons is mediated by activation of the transcription factor activator protein 1 (AP-1). This transcription factor and its component proteins are upregulated in the rostral ventrolateral medulla of animals with CHF. Because the increase in AT(1)R expression and transcription factor activation can be blocked by the AT(1)R antagonist losartan, a positive feedback mechanism of AT(1)R expression in CHF is suggested. Oxidative stress has also been implicated in the regulation of receptor expression. Recent data suggest that the newly discovered catabolic enzyme angiotensin-converting enzyme 2 (ACE2) may play a role in the modulation of AT(1)R expression by altering the balance between the octapeptide ANG II and ANG- (1-7). Finally, exercise training reduces both central oxidative stress and AT(1)R expression in animals with CHF. These data strongly suggest that multiple central and peripheral influences dynamically alter AT(1)R expression in CHF.

Topics: Angiotensin I; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme 2; Animals; Chronic Disease; Exercise; Heart; Heart Failure; Humans; Medulla Oblongata; Neurons; Oxidative Stress; Peptide Fragments; Peptidyl-Dipeptidase A; Receptor, Angiotensin, Type 1; Signal Transduction; Sympathetic Nervous System; Transcription Factor AP-1; Transcription, Genetic; Up-Regulation

Heart failure is a major healthcare problem and leading cause of death in Western countries. Growing evidence has shown recent improvements in pharmacological therapy, such as receptor-regulating agents, in treating heart failure; however, the morbidity and mortality of heart failure is still high. More recent studies have suggested the presence of additional molecular targets for treating heart failure. Several key molecules in the beta adrenergic receptor signaling pathway play an important role in the progression of heart failure, and transgenic mice studies supported beneficial effects of controlling such molecules in heart failure. In addition, molecules in the renin-angiotensin system or calcium signaling pathway may also be potential targets for treating heart failure. In this review, we focused on putative mechanisms underlying the beneficial effects of regulating these molecules on the progression of heart failure including relevant patents on this topic.

Topics: Adrenergic beta-Antagonists; Angiotensin I; Angiotensin II Type 1 Receptor Blockers; Animals; Apoptosis; Calcium Signaling; Heart Failure; Humans; Mice; Patents as Topic; Renin-Angiotensin System

Angiotensin II (Ang II), a bioactive peptide of the renin-angiotensin system (RAAS), plays an important role in the development of cardiovascular diseases (CVD). Pharmacological inhibition of angiotensin-converting enzyme (ACE), the Ang II forming enzyme, or specific blockade of Ang II binding to angiotensin type 1 receptor (AT1R) through which it exerts its deleterious effects, were shown to provide some protection against progression of CVD. The ACE-Ang II-AT1R axis has been challenged over the last few years with RAAS components able to counterbalance the effects of the main axis. The ACE homologue ACE2 efficiently hydrolyses Ang II to form Ang (1-7), a peptide that exerts actions opposite to those of Ang II. In contrast to the Ang II axis, the role of the ACE2-Ang (1-7) axis in cardiac function is largely obscure. Ang (1-7) is present in the viable myocardium, and its formation depends on Ang II as a substrate. The expression of this peptide is associated with cardiac remodeling: it is lost in the infarcted area and significantly increased in the border area. Low doses of Ang (1-7) improve cardiac output and antagonize Ang II-induced vasoconstriction. The type of Ang (1-7) biological activity is tissue specific and dose dependent. These findings point to a possible protective role for Ang (1-7) in abating the Ang II-induced actions. The elevated expression of Ang (1-7) in failing heart tissue paralleled the expression of its forming enzyme, ACE2. Several observations and experimental evidence suggest a beneficial role for ACE2 in cardiovascular function. Elevated ACE2 expression at the initial stage of several pathologies which decline with progression of disease might indicate a protective role for ACE2. Genetic manipulation of ACE2 expression, either targeted disruption or overexpression, point to the possible significance of this enzyme in cardiac function. Based on the above, a therapeutic approach that will amplify the ACE2-Ang (1-7) axis could provide further protection against the development of CVD. It turns out that the merits of currently used drugs--ACE inhibitors, AT1R blockers and mineralocorticoid receptor blockers (MRB) - lay beyond their direct effects on suppression of the ACE-Ang II-AT1R axis as they also increase cardiac ACE2 and Ang (1-7) significantly.

Topics: Angiotensin I; Angiotensin-Converting Enzyme 2; Angiotensin-Converting Enzyme Inhibitors; Animals; Antihypertensive Agents; Disease Progression; Heart Failure; Humans; Myocardium; Peptide Fragments; Peptidyl-Dipeptidase A; Receptor, Angiotensin, Type 1; Ventricular Remodeling

This is the third part in a series of papers dealing with various aspects of clinical pharmacology of the first AT(1)-receptor antagonist losartan and its therapeutic use in hypertension, diabetic nephropathy, chronic heart failure, and acute phase of myocardial infarction. This part contains review of literature data concerning the use of losartan for the treatment of chronic heart failure and high risk patients after myocardial infarction. Efficacy and safety of losartan in these conditions was demonstrated in two major randomized trials. In one of these trials effects of the drug were studied in patients with chronic heart failure and in the second one therapy with losartan was started in acute period of myocardial infarction.

Topics: Angiotensin I; Angiotensin Receptor Antagonists; Antihypertensive Agents; Heart Failure; Humans; Losartan; Myocardial Infarction; Prognosis; Randomized Controlled Trials as Topic; Treatment Outcome

Inhibition of angiotensin II action or its formation by angiotensin-converting enzyme has been highly successful in the treatment of cardiovascular diseases. Since the identification of chymase as a major angiotensin II-forming enzyme in the human heart and its vessels more than a decade ago, numerous studies have sought to understand the importance of this enzyme in tissue angiotensin II formation and in the pathogenesis of hypertension, congestive heart failure, and vascular disease. Recent studies show that chymase and angiotensin-converting enzyme regulate angiotensin II production in distinct tissue compartments and that, in the pathogenesis of cardiovascular diseases, chymase-dependent effects extend beyond its ability to regulate tissue angiotensin II levels.

Topics: Angiotensin I; Angiotensin II; Arteriosclerosis; Cardiomegaly; Cardiovascular Diseases; Chymases; Heart Diseases; Heart Failure; Humans; Hypertension; Peptidyl-Dipeptidase A; Serine Endopeptidases

Chronic pharmacotherapy of congestive heart failure deals with its special pathophysiology and acts on different sites of the cardiorenal axis. The standard-therapy consists of diuretics, ACE-inhibitors and beta-blockers and can be supplemented by cardiac glycosides, if heart failure worsens. Cardiac glycosides are also administered if tachycardic arrhythmias occur. Aldosterone-antagonists are combined with standard therapy in NYHA III - IV to counteract cardiac remodelling. AT1-antagonists are indicated when ACE-inhibitors are contraindicated or cannot be administered because of side-effects. Combination with ACE-inhibitors and AT1-antagonists may be of benefit for the patient since morbidity and hospitalization decrease.

Topics: Adrenergic beta-Antagonists; Angiotensin I; Angiotensin-Converting Enzyme Inhibitors; Cardiac Glycosides; Diuretics; Heart Failure; Humans; Mineralocorticoid Receptor Antagonists; Vasodilator Agents

In all industrial nations the number of patients with heart hailure is increasing. Pharmacological treatment with Angiotensin-converting enzyme (ACE) inhibitors and beta blockers improve survival and reduce hospitalization in these patients. Inspite of these therapies, morbidity and mortality remains problematic. Possibly phenomena like the genetic induced Angiotensin-II-escape are responsible for the individual response in patients. Regarding their different pharmacological effects the new group of Angiotensin-II type 1 receptor (AT1) blockers seem to be promising for the treatment of heart failure. In trials like ELITE 1, ELITE 2 and Val-HeFT it could be demonstrated that AT1-blockers and ACE-inhibitors have a comparable effect in improving survival of heart failure patients. In the Val-HeFT study the combination of an ACE-inhibitor and an AT1-blocker reduce hospitalization and improve quality of life of heart failure patients compared with single treatment using an ACE-inhibitor or AT1-blocker. Mortality showed no significant difference. Before a final assessment of the combination treatment with ACE-inhibitors and AT1- blockers in heart failure patients we need more studies like the present CHARM-study.

Topics: Angiotensin I; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Drug Therapy, Combination; Heart Failure; Humans

Although interruption of the renin-angiotensin system with angiotensin converting enzyme (ACE) inhibitors has evolved as the therapy of choice in heart failure based on large-scale morbidity and mortality clinical studies, treatment with angiotensin type 1 receptor blockers (ARB) offers an alternative and potentially superior method of treating this condition. Early pilot studies were quite promising; however, two well designed, large-scale trials have shown that the reduction in heart failure mortality with ARB is not significantly different from the reduction with ACE inhibitors. Possible reasons for lack of ARB superiority include insufficient dosing of ARB, differences in effects mediated through angiotensin II type 2 receptors, interaction with beta-blockers, and bradykinin-mediated effects specific to ACE inhibitors. The ACE inhibitors remain the current therapy of choice in treating heart failure until further outcomes trial data become available; however, ARB are a reasonable alternative in patients intolerant of ACE inhibitors.

Topics: Angiotensin I; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Clinical Trials as Topic; Forecasting; Heart Failure; Humans; Losartan; Renin-Angiotensin System

In the effort to explain gender-related differences of the cardiovascular system, the renin-angiotensin system experienced intensive exploration. Indeed, the development of hypertension as well as the progression of coronary artery disease and heart failure have two factors in common: (1) display distinct gender specific characteristics and (2) are enhanced by the renin-angiotensin system. It is therefore interesting to note that data from experimental animals, epidemiological surveys, and clinical investigations suggest that the components of the circulating as well as tissue-based renin-angiotensin system are markedly affected by gender. However, the issue is complicated by counter-regulatory effects of estrogen on the system with the substrate, on one hand, and the processing enzymes as well as the chief receptor, on the other hand. In fact, angiotensinogen is up-regulated particularly by oral administration of estrogen, whereas renin, angiotensin-converting enzyme (ACE), and AT-1 receptor are down-regulated by the hormone. While under well-defined experimental conditions the net effect of estrogen appears to result in suppression of the renin-angiotensin system, the clinical situation may be more complex. The judgment is further complicated by the difficulty in precisely measuring the activity of the system at the tissue level. Moreover, clinically relevant read-outs for the activity of the renin-angiotensin system may be regulated multifactorially or only indirectly affected by the system. Nevertheless, the undisputable, profound biochemical changes in the renin-angiotensin system related to the estrogen status allow speculation that such interaction explains some of the differences in the cardiovascular system of men and women.

Topics: Angiotensin I; Cardiovascular Physiological Phenomena; Coronary Disease; Estrogens; Female; Genotype; Heart Failure; Humans; Hypertension; Male; Renin; Renin-Angiotensin System; Sex

Topics: Angiotensin I; Angiotensin Receptor Antagonists; Animals; Antihypertensive Agents; Clinical Trials as Topic; Diabetic Nephropathies; Heart Failure; Humans; Hypertension; Receptors, Angiotensin; Renin-Angiotensin System

Topics: Angiotensin I; Angiotensin Receptor Antagonists; Antihypertensive Agents; Bradykinin; Heart Failure; Humans; Hypertension; Nitric Oxide; Randomized Controlled Trials as Topic; Renin-Angiotensin System

Topics: Age Factors; Aged; Angiotensin I; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Anti-Arrhythmia Agents; Antihypertensive Agents; Benzimidazoles; Biphenyl Compounds; Captopril; Clinical Trials as Topic; Death, Sudden, Cardiac; Enalapril; Heart Failure; Humans; Losartan; Prodrugs; Prognosis; Randomized Controlled Trials as Topic; Risk Factors; Tetrazoles; Time Factors

Topics: Acute Disease; Adrenergic beta-Antagonists; Aged; Analgesics, Opioid; Angioplasty, Balloon, Coronary; Angiotensin I; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Cardiac Glycosides; Defibrillators, Implantable; Diuretics; Emergencies; Furosemide; Heart Failure; Humans; Morphine; Myocardial Infarction; Nitrates; Nitroglycerin; Pacemaker, Artificial; Prognosis; Pulmonary Edema; Respiration, Artificial; Risk Factors; Shock, Cardiogenic; Time Factors; Vasodilator Agents; Ventricular Dysfunction, Right

The octapeptide hormone, angiotensin II, binds to two major subtypes of cell surface receptors: the AT1 and the AT2 angiotensin receptors. The important physiological and pathophysiological effects of angiotensin II on cardiovascular regulation and salt-water balance are mediated by the AT1 receptor subtype. As a consequence of the outstanding clinical success of angiotensin-converting enzyme inhibitors, the appearance of AT1 receptor inhibitors in the therapy of hypertension and other cardiovascular diseases was preceded with great expectations. The available experimental and clinical data indicate that the first AT1 receptor inhibitor, losartan, has the same therapeutic potential as angiotensin-converting enzyme inhibitors, but it does not evoke the angiotensin-independent side-effects of ACE inhibitors, such as dry cough or angioedema. The physiological importance and the biochemical, molecular biological and pharmacological properties of AT1 and AT2 receptors are reviewed in this paper, and a summary of the available clinical data is presented.

Topics: Angiotensin I; Angiotensin II; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Anti-Arrhythmia Agents; Antihypertensive Agents; Arrhythmias, Cardiac; Female; Heart Failure; Humans; Hypertension; Losartan; Renin-Angiotensin System

Improvement of symptoms and, accordingly, quality of life, as well as prolongation of life, are the objectives of drug therapy in congestive heart failure patients. Diuretics are most effective in relieving symptoms related to congestion, and angiotensin converting enzyme inhibitors improve exercise capacity, reduce the incidence of decompensations and hence hospitalizations, and prolong life. Angiotensin type-1 receptor antagonists also seem to improve survival, while digoxin improves symptoms and morbidity but not survival in patients in sinus rhythm. The value of prophylactic antiarrhythmic therapy with amiodarone and oral anticoagulation in the presence of sinus rhythm is not established, and the role of newer dihydropyridine calcium antagonists and betablockers is also not precisely defined. These agents should only be considered in selected cases after careful consideration of potential advantages and risks, and should usually be used as an addition to established therapy. Better understanding of the pathophysiology of congestive heart failure will lead to the development of new treatment concepts, the clinical relevance of which will have to be tested in appropriately designed clinical trials.

Topics: Adrenergic beta-Antagonists; Angiotensin I; Angiotensin Receptor Antagonists; Anti-Arrhythmia Agents; Calcium Channel Blockers; Cardiotonic Agents; Diuretics; Drugs, Investigational; Heart Failure; Humans; Severity of Illness Index; Ventricular Dysfunction, Left

Extracellular matrix (ECM) in the heart and vascular wall includes fibrous proteins and proteoglycans. Fibrous proteins are classified within two categories: structural (collagen and elastin) and adhesive molecules (laminin and fibronectin). These ECM components are important in maintenance of both structure and function of the heart and vascular tissues. Myocardial infarction, hypertrophy, hypertension and heart failure are well known to be associated with progressive cardiac fibrosis. Vascular hypertrophy and thickening has been associated with the pathological series of events that attends both hypertension and restenosis. The accumulation of ECM in the cardiovascular system plays an important role in the development of heart failure after myocardial infarction and hypertension, as well as in vascular hypertrophy and restenosis. Angiotensin II (angiotensin) and transforming growth factor beta 1 are known to play a role in signalling the abnormal accumulation of ECM in these cardiovascular diseases. Administration of angiotensin-converting enzyme inhibitor or angiotensin receptor type 1 antagonist is associated with regression of cardiac hypertrophy and fibrosis as well as vascular hypertrophy.

Topics: Angiotensin I; Angiotensin-Converting Enzyme Inhibitors; Cardiomegaly; Cardiovascular Diseases; Collagen; Elastin; Extracellular Matrix; Fibronectins; Heart Failure; Humans; Myocardial Infarction; Proteoglycans

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Animals; Blood Circulation; Blood Pressure; Heart Failure; Humans; Hypertension; Renin-Angiotensin System

The therapeutic benefits of angiotensin-converting enzyme inhibitors in the treatment of hypertension, congestive heart failure, and atherosclerotic heart disease are undeniable. Recent studies, however, suggest that the cardioprotective effect produced by these drugs is complex and may not be solely related to inhibition of the generation of angiotensin II. An alternative pathway for the generation of angiotensin II from angiotensin I has been proposed, following the recent identification of a chymotrypsin-like protease (chymase) that may contribute to the formation of angiotensin II in human heart tissue. The enzyme is present in cardiac mast cells and displays unusual substrate specificity for the conversion of angiotensin I to angiotensin II. While biochemical studies have provided convincing evidence for a chymase-dependent production of angiotensin II, the contribution of this enzyme to the physiologic or pathological regulation of arterial pressure and cardiac function remains undetermined.

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Chymases; Coronary Artery Disease; Heart Failure; Humans; Hypertension; Myocardium; Renin-Angiotensin System; Serine Endopeptidases

Enalapril maleate is a prodrug which when administered orally is hydrolysed to release the active converting enzyme inhibitor enalaprilat. Enalapril maleate is 60% absorbed and 40% bioavailable as enalaprilat. Both compounds undergo renal excretion without further metabolism. The functional half-life for accumulation of enalaprilat is 11 h, and this is increased in the presence of a reduction in renal function. Inhibition of converting enzyme inhibition is associated with reductions in plasma angiotensin II and plasma aldosterone, and with increases in plasma renin activity and plasma angiotensin I. Acute and chronic effects have been reviewed. When given with hydrochlorothiazide, enalapril attenuates the secondary aldosteronism and ameliorates the hypokalaemia from diuretics. Both acutely and chronically in patients with essential hypertension, enalapril reduced blood pressure with a rather flat dose-response curve. No evidence of a triphasic response such as seen with captopril has been demonstrated with enalapril, and blood pressure returns smoothly to pretreatment levels when the drug is abruptly discontinued. Once- or twice-daily dosing gives similar results. The antihypertensive effects of enalapril are potentiated by hydrochlorothiazide. Haemodynamically, blood pressure reduction is associated with a reduced peripheral vascular resistance and an increase in cardiac output and stroke volume with little change in heart rate. Renal vascular resistance decreases, and renal blood flow may increase without an increase in glomerular filtration in patients with normal renal function. In patients with essential hypertension and glomerular filtration rates below 80 ml/min/m2, both renal blood flow and glomerular filtration rates may increase.

Topics: Aldosterone; Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Bradykinin; Dipeptides; Drug Administration Schedule; Enalapril; Enalaprilat; Heart Failure; Heart Rate; Humans; Hydrochlorothiazide; Hypertension; Kidney; Kidney Failure, Chronic; Norepinephrine; Prostaglandins; Renal Circulation; Renin

Plasma aldosterone levels are elevated in patients with chronic heart failure (CHF) taking angiotensin-converting enzyme (ACE) inhibitors. Elevated aldosterone levels may reflect incomplete inhibition of the vascular converting enzyme during long-term ACE inhibition. We simultaneously measured plasma aldosterone levels and the degree of inhibition of the vascular converting enzyme in patients with CHF.. Thirty-four subjects with CHF receiving the maximum recommended doses of ACE inhibitors for a duration of 3 to 105 months were studied. The pressor response to exogenous angiotensin I (AI) was measured and normalized for the pressor response to angiotensin II (AII) to assess inhibition of the vascular converting enzyme (AII/AI ratio). Aldosterone levels were determined by solid-phase radioimmunoassay. Eleven of the 34 subjects had plasma aldosterone levels above the upper limit of normal, ie, >15.0 ng/dL. Seven of these 11 subjects (64%) had an AII/AI ratio < or =0.05, indicating complete inhibition of the vascular converting enzyme. In the entire cohort, the AII/AI ratio did not correlate with the duration of ACE inhibitor therapy.. Plasma aldosterone levels are elevated in patients with CHF during long-term ACE inhibitor therapy despite complete inhibition of the vascular converting enzyme. Complete inhibition of the vascular converting enzyme does not obviate the need for aldosterone receptor blockade in patients with CHF.

Topics: Aldosterone; Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Blood Pressure; Chronic Disease; Enzyme Activation; Female; Heart Failure; Humans; Male; Middle Aged; Peptidyl-Dipeptidase A; Radial Artery; Sodium, Dietary; Tonometry, Ocular; Treatment Outcome

This study was designed to fully characterize vascular tissue angiotensin I (AI)/angiotensin II (AII) conversion changes over time in vivo in humans during chronic angiotensin-converting enzyme (ACE) inhibitor therapy.. Plasma AII does not remain fully suppressed during chronic ACE inhibitor therapy. However, the plasma renin angiotensin system (RAS) might be dissociated from the vascular tissue RAS. We therefore set out to characterize the time course of vascular RAS reactivation during chronic ACE inhibitor therapy.. Vascular AI/AII conversion was studied in patients with chronic heart failure (CHF) taking chronic lisinopril therapy by the differential infusion of AI and AII into the brachial artery. A cross-sectional study was done to see whether there were differences in vascular AI/AII conversion according to New York Heart Association (NYHA) class. A second longitudinal study followed 28 patients with NYHA I to II CHF serially over 18 months to see whether vascular ACE inhibition was progressively lost with time despite ACE inhibitor therapy. A third study examined whether increasing the dose of lisinopril affected subsequent vascular ACE inhibition.. In the cross-sectional study, vascular AI-to-AII conversion was significantly reduced in NYHA class III compared with class I/II (p < 0.05). In the longitudinal study, vascular ACE inhibition was significantly reduced at 18 months as compared with baseline (p < 0.001), suggesting gradual reactivation of vascular ACE in CHF over time. In the third study, tissue ACE inhibition could be restored by increasing the ACE inhibitor dose.. Vascular AI/AII conversion reactivates over time during chronic ACE inhibitor therapy even if the CHF disease process is clinically stable. It also occurs as the CHF disease process progresses. Even if vascular AI/AII conversion has reactivated, it can be suppressed by increasing the dose of the ACE inhibitor.

Topics: Aged; Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Blood Vessels; Chronic Disease; Cross-Over Studies; Cross-Sectional Studies; Double-Blind Method; Female; Heart Failure; Humans; Lisinopril; Longitudinal Studies; Male; Middle Aged; Time Factors

The RALES study showed that spironolactone, added to conventional therapy for chronic heart failure, dramatically reduced mortality. We tested the hypothesis that this benefit was partially due to improvement in endothelial function and/or to amplified suppression of the vascular renin-angiotensin axis.. We performed a randomized, placebo-controlled, double-blind crossover study on 10 patients with NYHA class II to III chronic heart failure on standard diuretic/ACE inhibitor therapy, comparing 50 mg/d spironolactone (1 month) versus placebo. Forearm vasculature endothelial function was assessed by bilateral forearm venous occlusion plethysmography using acetylcholine and N-monomethyl-L-arginine (L-NMMA), with sodium nitroprusside as a control vasodilator. Also, vascular ACE activity was assessed by use of angiotensin (Ang) I, with Ang II as a control vasoconstrictor. Spironolactone significantly increased the forearm blood flow response to acetylcholine (percentage change in forearm blood flow [mean+/-SEM], 177+/-29% versus 95+/-20%, spironolactone versus placebo; P<0.001), with an associated increase in vasoconstriction due to L-NMMA (-35+/-6% versus -18+/-4%; P<0.05). The Ang I response was also significantly reduced with spironolactone (P<0.05), with Ang II responses unaltered.. Spironolactone improves endothelial dysfunction, increases NO bioactivity, and inhibits vascular Ang I/Ang II conversion in patients with heart failure, providing novel mechanisms for its beneficial effect on cardiovascular mortality.

Topics: Aged; Angiotensin I; Angiotensin II; Chronic Disease; Cross-Over Studies; Diuretics; Double-Blind Method; Endothelium, Vascular; Enzyme Inhibitors; Forearm; Heart Failure; Humans; Male; Middle Aged; Nitric Oxide; omega-N-Methylarginine; Spironolactone; Vasodilation

This study was designed to compare different proposed methods of assessing adherence with angiotensin-converting enzyme (ACE) inhibitor (ACEI) therapy in chronic heart failure.. The use of ACEIs in chronic heart failure gives us a unique opportunity to assess a patient's adherence by measuring whether the expected biochemical effect of an ACEI is present in the patient's bloodstream. In fact, there are several different ways of assessing ACE in vivo: these are serum ACE activity itself, plasma N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP), urine AcSDKP, plasma angiotensin I (AI), plasma angiotensin II (AII), or the AII/AI ratio.. Patients with chronic heart failure (n = 39) were randomized to regimens of ACEI nonadherence for one week, ACEI adherence for one week or two versions of partial adherence for one week, after which the above six tests were performed.. All six tests significantly distinguished between full nonadherence for one week and full or partial adherence. Only plasma AcSDKP produced a significantly different result between partial adherence and either full adherence or full nonadherence for one week. In terms of their ability to distinguish full nonadherence from full adherence, plasma AcSDKP was 89% sensitive and 100% specific with an area under its ROC of 0.95. Corresponding figures for urine AcSDKP were 92%, 97% and 0.95 and for serum ACE they were 86%, 95% and 0.90.. All six tests distinguished full nonadherence from all other forms of adherence. The rank order of performance was plasma AcSDKP, urine AcSDKP, serum ACE, AII/AI ratio and plasma AII followed by plasma AI.

Topics: Aged; Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Biomarkers; Chronic Disease; Diuretics; Drug Therapy, Combination; Echocardiography; Furosemide; Heart Failure; Humans; Lisinopril; Oligopeptides; Peptidyl-Dipeptidase A; Radionuclide Ventriculography; Treatment Outcome; Treatment Refusal

The octapeptide hormone, angiotensin II, binds to two major subtypes of cell surface receptors: the AT1 and the AT2 angiotensin receptors. The important physiological and pathophysiological effects of angiotensin II on cardiovascular regulation and salt-water balance are mediated by the AT1 receptor subtype. As a consequence of the outstanding clinical success of angiotensin-converting enzyme inhibitors, the appearance of AT1 receptor inhibitors in the therapy of hypertension and other cardiovascular diseases was preceded with great expectations. The available experimental and clinical data indicate that the first AT1 receptor inhibitor, losartan, has the same therapeutic potential as angiotensin-converting enzyme inhibitors, but it does not evoke the angiotensin-independent side-effects of ACE inhibitors, such as dry cough or angioedema. The physiological importance and the biochemical, molecular biological and pharmacological properties of AT1 and AT2 receptors are reviewed in this paper, and a summary of the available clinical data is presented.

Topics: Angiotensin I; Angiotensin II; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Anti-Arrhythmia Agents; Antihypertensive Agents; Arrhythmias, Cardiac; Female; Heart Failure; Humans; Hypertension; Losartan; Renin-Angiotensin System

Quinapril is converted to quinaprilat, a long-acting angiotensin converting enzyme (ACE) inhibitor, and is currently being studied for the treatment of hypertension and congestive heart failure. In studies of healthy volunteers, single quinapril doses of 0.625 mg to 80 mg inhibited plasma ACE activity for up to forty-eight hours. Dose-related inhibition of angiotensin I pressor response occurred after administration of quinapril doses of 0.625 mg to 20 mg. In addition, plasma renin activity increased and aldosterone and angiotensin II concentrations decreased following single or multiple doses of quinapril. Subsequently, dose-ranging studies were conducted in patients with mild to moderate hypertension and congestive heart failure. Pilot studies suggested that 5 mg of quinapril given once daily had minimal antihypertensive effect. Therefore, a definitive, multiple-dose, placebo-controlled, double-blind study of 5, 10, and 20 mg once daily doses of quinapril was performed. Quinapril doses of 10 mg and 20 mg were statistically significantly superior to placebo (p less than 0.05) in lowering sitting diastolic blood pressure (DBP), whereas 5 mg of quinapril had only marginal clinical effectiveness. A twenty-four-hour blood pressure monitoring study indicated that quinapril administered once or twice daily effectively lowered DBP in patients with mild to moderate hypertension. This study suggested, however, that some patients may not achieve sustained reductions in DBP over the entire twenty-four-hour interval with quinapril administered once daily and may require twice daily therapy. In studies of patients with refractory congestive heart failure, acute favorable hemodynamic effects were demonstrated after the administration of quinapril.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adolescent; Adult; Aged; Angiotensin I; Angiotensin-Converting Enzyme Inhibitors; Clinical Trials as Topic; Dose-Response Relationship, Drug; Double-Blind Method; Female; Heart Failure; Hemodynamics; Humans; Hypertension; Isoquinolines; Male; Middle Aged; Multicenter Studies as Topic; Peptidyl-Dipeptidase A; Quinapril; Random Allocation; Tetrahydroisoquinolines

Topics: Angiotensin I; Angiotensin II; Animals; Cardiomegaly; Heart Failure; Kidney; Peptide Fragments; Rats; Renin-Angiotensin System

Topics: Angiotensin I; Animals; Diabetes Mellitus; Endothelium, Vascular; Heart Failure; Mice; Nitric Oxide Synthase Type III; Peptide Fragments; Phenotype; Stroke Volume

The myocardium exhibits an adaptive tissue-specific renin-angiotensin system (RAS), and local dysbalance may circumvent the desired effects of pharmacologic RAS inhibition, a mainstay of heart failure with reduced ejection fraction (HFrEF) therapy.. This study sought to investigate human myocardial tissue RAS regulation of the failing heart in the light of current therapy.. Fifty-two end-stage HFrEF patients undergoing heart transplantation (no RAS inhibitor: n = 9; angiotensin-converting enzyme [ACE] inhibitor: n = 28; angiotensin receptor blocker [ARB]: n = 8; angiotensin receptor neprilysin-inhibitor [ARNi]: n = 7) were enrolled. Myocardial angiotensin metabolites and enzymatic activities involved in the metabolism of the key angiotensin peptides angiotensin 1-8 (AngII) and Ang1-7 were determined in left ventricular samples by mass spectrometry. Circulating angiotensin concentrations were assessed for a subgroup of patients.. AngII and Ang2-8 (AngIII) were the dominant peptides in the failing heart, while other metabolites, especially Ang1-7, were below the detection limit. Patients receiving an ARB component (i.e., ARB or ARNi) had significantly higher levels of cardiac AngII and AngIII (AngII: 242 [interquartile range (IQR): 145.7 to 409.9] fmol/g vs 63.0 [IQR: 19.9 to 124.1] fmol/g; p < 0.001; and AngIII: 87.4 [IQR: 46.5 to 165.3] fmol/g vs 23.0 [IQR: <5.0 to 59.3] fmol/g; p = 0.002). Myocardial AngII concentrations were strongly related to circulating AngII levels. Myocardial RAS enzyme regulation was independent from the class of RAS inhibitor used, particularly, a comparable myocardial neprilysin activity was observed for patients with or without ARNi. Tissue chymase, but not ACE, is the main enzyme for cardiac AngII generation, whereas AngII is metabolized to Ang1-7 by prolyl carboxypeptidase but not to ACE2. There was no trace of cardiac ACE2 activity.. The failing heart contains considerable levels of classical RAS metabolites, whereas AngIII might be an unrecognized mediator of detrimental effects on cardiovascular structure. The results underline the importance of pharmacologic interventions reducing circulating AngII actions, yet offer room for cardiac tissue-specific RAS drugs aiming to limit myocardial AngII/AngIII peptide accumulation and actions.

Topics: Angiotensin I; Angiotensin II; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Disease Progression; Female; Heart Failure; Heart Transplantation; Humans; Male; Mass Spectrometry; Middle Aged; Myocardium; Peptide Fragments; Renin-Angiotensin System; Stroke Volume

Sodium restriction is often recommended in heart failure (HF) to block symptomatic edema, despite limited evidence for benefit. However, a low-sodium diet (LSD) activates the classical renin-angiotensin-aldosterone system (RAAS), which may adversely affect HF progression and mortality in patients with dilated cardiomyopathy (DCM). We performed a randomized, blinded pre-clinical trial to compare the effects of a normal (human-equivalent) sodium diet and a LSD on HF progression in a normotensive model of DCM in mice that has translational relevance to human HF. The LSD reduced HF progression by suppressing the development of pleural effusions (

Topics: Angiotensin I; Animals; Biological Availability; Biomarkers; Blood Pressure; Cardiomyopathy, Dilated; Cyclic GMP; Diet, Sodium-Restricted; Edema; Heart Failure; Kidney; Male; Mice, Inbred C57BL; Natriuretic Peptide, Brain; Nitric Oxide; Nitric Oxide Synthase; Peptide Fragments; Phosphoric Diester Hydrolases; Pleural Effusion; Renin-Angiotensin System; Survival Analysis; Systole

Topics: Angiotensin I; Heart Failure; Heart Ventricles; Humans; Renin-Angiotensin System

Isoproterenol (ISO)-induced heart failure is a standardized model for the study of beneficial effects of various drugs. Both apelin and angiotensin 1-7 have a cardiac protective effect. We assumed that co-therapy with apelin and angiotensin 1-7 (Ang (1-7)) may have synergistic cardioprotective effects against isoproterenol-induced heart failure. Methods The animals were randomly assigned to one of eight groups of seven animals in each group as follows: (1) control I (saline; IP injection) (1) control II (saline; via mini-osmotic pump) (3) ISO (5 mg/ kg; IP), (4) Apelin (20μg/ kg; IP), (5) Ang (1-7) (30 μg/kg/day; via mini-osmotic pump), (6) Apelin+ISO, (7) Ang (1-7)+ISO, (8) Apelin+Ang (1-7)+ISO. Rat myocardial injury was induced by intraperitoneal injection of 5mg/kg of ISO for ten days. Apelin and Ang (1-7) were administered 30 minutes before ISO injection.. A decrease in systolic blood pressure (SBP; p<0.001), diastolic blood pressure (DBP; p<0.05), left ventricular systolic pressure (LVSP; p<0.001), left ventricular contractility (dP / dt max; p<0.001), relaxation (dP / dt min; p<0.001) and an increase in left ventricular end-diastolic pressure (LVEDP; p<0.001) were observed in ISO-treated rats. Plasma LDH and myocardial and plasma MDA were higher in the ISO heart than in controls (P<0.001). Histopathological examination of cardiac tissue showed myocardial fibrosis and leukocyte infiltration in ISO-treated rats as compared to control. Co- therapy with apelin and Ang (1-7) was more effective than either agent used alone in restoring these parameters to that of control rats.. The results of this study showed that the combination of apelin and ang (1-7) had a more cardioprotective effect than either used alone against ISO-induced heart failure, and co-therapy may be a useful treatment option for myocardial injuries and heart failure.

Topics: Adrenergic beta-Agonists; Angiotensin I; Animals; Apelin; Cardiomegaly; Heart Failure; Hemodynamics; Isoproterenol; L-Lactate Dehydrogenase; Male; Malondialdehyde; Myocardium; Peptide Fragments; Random Allocation; Rats; Rats, Sprague-Dawley; Vasodilator Agents

Elucidation of the role of angiotensin-converting enzyme (ACE) 2 (ACE2)/angiotensin (Ang)-(1-7)/Mas receptor axis in heart failure is necessary. No previous study has reported serial changes in ACE2 and Ang-(1-7) concentrations after optimal therapy (OT) in acute heart failure (AHF) patients. We aimed to investigate serial changes in serum ACE2 and Ang-(1-7) concentrations after OT in AHF patients with reduced ejection fraction (EF).. ACE2 and Ang-(1-7) concentrations were measured in 68 AHF patients with reduced EF immediately after admission and 1 and 3 months after OT. These parameters were compared with the healthy individuals at three time points.. In the acute phase, Ang-(1-7) and ACE2 concentrations was statistically significantly lower and higher in AHF patients than the healthy individuals (2.40 ± 1.11 vs. 3.1 ± 1.1 ng/ml, P<0.005 and 7.45 ± 3.13 vs. 4.84 ± 2.25 ng/ml, P<0.005), respectively. At 1 month after OT, Ang-(1-7) concentration remained lower in AHF patients than the healthy individuals (2.37 ± 1.63 vs. 3.1 ± 1.1 ng/ml, P<0.05); however, there was no statistically significant difference in ACE2 concentration between AHF patients and the healthy individuals. At 3 months after OT, there were no statistically significant differences in Ang-(1-7) and ACE2 concentrations between AHF patients and the healthy individuals.. ACE2 concentration was equivalent between AHF patients and the healthy individuals at 1 and 3 months after OT, and Ang-(1-7) concentration was equivalent at 3 months after OT.

Topics: Aged; Angiotensin I; Angiotensin-Converting Enzyme 2; Biomarkers; Case-Control Studies; Female; Heart Failure; Humans; Male; Middle Aged; Peptide Fragments; Recovery of Function; Stroke Volume; Time Factors; Treatment Outcome; Ventricular Function, Left

Heart transplantation is often an unrealizable therapeutic option for end-stage heart failure, which is why mechanical left ventricular assist devices (LVADs) become an increasingly important therapeutic alternative. Currently, there is a lack of information about molecular mechanisms which are influenced by LVADs, particularly regarding the pathophysiologically critical renin angiotensin system (RAS). We, therefore, determined regulation patterns of key components of the RAS and the β-arrestin signaling pathways in left ventricular (LV) tissue specimens from 8 patients with end-stage ischemic cardiomyopathy (ICM) and 12 patients with terminal dilated cardiomyopathy (DCM) before and after LVAD implantation and compared them with non-failing (NF) left ventricular tissue samples: AT1R, AT2R, ACE, ACE2, MasR, and ADAM17 were analyzed by polymerase chain reaction. ERK, phosphorylated ERK, p38, phosphorylated p38, JNK, phosphorylated JNK, GRK2, β-arrestin 2, PI3K, Akt, and phosphorylated Akt were determined by Western blot analysis. Angiotensin I and Angiotensin II were quantified by mass spectrometry. Patients were predominantly middle-aged (53 ± 10 years) men with severely impaired LV function (LVEF 19 ± 8%), when receiving LVAD therapy for a mean duration of 331 ± 317 days. Baseline characteristics did not differ significantly between ICM and DCM patients. By comparing failing with non-failing left ventricles, i.e., before LVAD implantation, a downregulation of AT1R, AT2R, and MasR and an upregulation of ACE, ACE2, GRK, β-arrestin, ERK, PI3K, and Akt were seen. Following LVAD support, then angiotensin I, ACE2, GRK, and β-arrestin were downregulated and AT2R, JNK, and p38 were upregulated. ACE, angiotensin II, AT1R, ADAM17, MasR, ERK, PI3K, and Akt remained unchanged. Some regulation patterns were influenced by the underlying etiology of heart failure, the severity of LV dysfunction at baseline, and the duration of LVAD therapy. Key components of the RAS and β-arrestin signaling pathways were divergently altered in failing left ventricles both before and after LVAD implantation, whereas a remarkable fraction remained unchanged. This indicates a rather incomplete molecular reverse remodeling, whose functional relevance has to be further evaluated.

Topics: Angiotensin I; Angiotensin II; beta-Arrestins; Female; Heart Failure; Heart-Assist Devices; Humans; Male; Middle Aged; Proto-Oncogene Mas; ras Proteins; Renin-Angiotensin System; Signal Transduction

Cardiac remodeling is a common pathological manifestation of various end-stage cardiovascular diseases, which leads to myocardial diastolic and systolic dysfunction, low ejection fraction which cannot meet the needs of systemic tissue and organ metabolism, and ultimate progress into heart failure. Excessive activation of the classical renin angiotensin system (RAS), which is the angiotensin-converting enzyme-angiotensin II-type 1 angiotensin II receptor axis (ACE2-Ang II-AT1R axis), plays a key role in the pathological process of cardiac remodeling and heart failure. Angiotensin-converting enzyme 2-angiotensin (1-7)-Mas axis [ACE2-Ang (1-7)-Mas axis] is an endogenous negative regulatory pathway of classical RAS, which can reduce its harmful effects. ACE2 is a monocarboxypeptidase that can hydrolyse Ang II and produce Ang (1-7), which has cardio-protective effects. Ang (1-7), via endogenous receptor Mas, plays the role of vasodilating, anti-proliferation and anti-differentiation, anti-fibrosis, anti-thrombosis and reversing myocardial remodeling. In recent years, with increasingly growing studies on the ACE2-Ang (1-7)-Mas axis, there are more understanding about their metabolic characteristics and mechanism of action. This article describes the role of ACE2 and Ang (1-7) in cardiac remodeling and heart failure and the related mechanisms, and discusses the potential benefits by regulating ACE2 activity and Ang (1-7) levels in clinical and experimental studies, hopefully providing potential therapeutic strategies.

Topics: Angiotensin I; Heart Failure; Humans; Peptide Fragments; Ventricular Remodeling

Simultaneous blockade of angiotensin receptors and enhancement of natriuretic peptides (NP) by the first-in-class angiotensin receptor neprilysin (NEP) inhibitor sacubitril/valsartan constitutes an effective approach to treating heart failure. This study examined the effects of sacubitril/valsartan (225 and 675 mg/day) vs. placebo, sacubitril (360 mg/day), valsartan (900 mg/day), and benazepril (5 mg/day) on the dynamics of the renin-angiotensin-aldosterone system (RAAS) and the NP system in dogs. Beagle dogs (n = 18) were fed a low-salt diet (0.05% Na) for 15 days to model RAAS activation observed in clinical heart failure. Drugs were administered once daily during the last 10 days, while the effects on the RAAS and NPs were assessed on Day 1, 5, and 10. Steady-state pharmacokinetics of the test agents were evaluated on Day 5. Compared with placebo, sacubitril/valsartan (675 mg) substantially increased cGMP circulating levels, while benazepril and valsartan showed no effect. Additionally, sacubitril/valsartan (675 mg) and valsartan significantly increased plasma renin activity, angiotensin I and angiotensin II concentrations. Finally, sacubitril/valsartan (both doses), and valsartan significantly decreased plasma aldosterone vs. placebo. Systemic exposure to valsartan following sacubitril/valsartan 675 mg administration was similar to that observed with valsartan 900 mg administration alone. Sacubitril/valsartan favorably modulates the dynamics of the renin and NP cascades through complementary NEP and RAAS inhibition.

Topics: Aldosterone; Aminobutyrates; Angiotensin I; Angiotensin II; Angiotensin Receptor Antagonists; Animals; Biphenyl Compounds; Cross-Over Studies; Cyclic GMP; Dogs; Dose-Response Relationship, Drug; Drug Combinations; Female; Heart Failure; Humans; Male; Natriuretic Peptides; Renin-Angiotensin System; Sodium, Dietary; Tetrazoles; Valsartan

Increasing evidence indicates that decreased brain blood flow, increased reactive oxygen species (ROS) production, and proinflammatory mechanisms accelerate neurodegenerative disease progression such as that seen in vascular contributions to cognitive impairment and dementia (VCID) and Alzheimer's disease and related dementias. There is a critical clinical need for safe and effective therapies for the treatment and prevention of cognitive impairment known to occur in patients with VCID and chronic inflammatory diseases such as heart failure (HF), hypertension, and diabetes. This study used our mouse model of VCID/HF to test our novel glycosylated angiotensin-(1-7) peptide Ang-1-6-O-Ser-Glc-NH2 (PNA5) as a therapy to treat VCID and to investigate circulating inflammatory biomarkers that may be involved. We demonstrate that PNA5 has greater brain penetration compared with the native angiotensin-(1-7) peptide. Moreover, after treatment with 1.0/mg/kg, s.c., for 21 days, PNA5 exhibits up to 10 days of sustained cognitive protective effects in our VCID/HF mice that last beyond the peptide half-life. PNA5 reversed object recognition impairment in VCID/HF mice and rescued spatial memory impairment. PNA5 activation of the Mas receptor results in a dose-dependent inhibition of ROS in human endothelial cells. Last, PNA5 treatment decreased VCID/HF-induced activation of brain microglia/macrophages and inhibited circulating tumor necrosis factor

Topics: Angiotensin I; Animals; Behavior, Animal; Biomarkers; Brain; Cognitive Dysfunction; Dementia, Vascular; Electrocardiography; Glycosylation; Half-Life; Heart Failure; Human Umbilical Vein Endothelial Cells; Humans; Inflammation; Male; Maze Learning; Memory; Mice; Peptide Fragments; Proto-Oncogene Mas; Proto-Oncogene Proteins; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Receptors, G-Protein-Coupled; Spatial Memory; Ventricular Remodeling

The dysfunctional nature of CD34 cells from patients with heart failure (HF) may make them unsuitable for autologous stem-cell therapy. In view of evidence that the vasoprotective axis of the renin-angiotensin system (RAS) improves CD34 cell functions, we hypothesized that CD34 cells from patients with HF will be dysfunctional and that angiotensin-(1-7) [Ang-(1-7)] would improve their function. Peripheral blood was collected from New York Heart Association class II-IV patients with HF (n = 31) and reference subjects (n = 16). CD34 cell numbers from patients with HF were reduced by 47% (P < 0.05) and also displayed 76% reduction in migratory capacity and 56% (P < 0.05) lower production of nitric oxide. These alterations were associated with increases in RAS genes angiotensin-converting enzyme and AT2R (595%, P < 0.05) mRNA levels and 80% and 85% decreases in angiotensin-converting enzyme 2 and Mas mRNA levels, respectively. Treatment with Ang-(1-7) enhanced CD34 cell function through increased migratory potential and nitric oxide production, and reduced reactive oxygen species generation. These data show that HF CD34 cells are dysfunctional, and Ang-(1-7) improves their functions. This suggests that activation of the vasoprotective axis of the RAS may hold therapeutic potential for autologous stem-cell therapy in patients with HF.

Topics: Angiotensin I; Antigens, CD34; Case-Control Studies; Cell Movement; Cells, Cultured; Female; Heart Failure; Hematopoietic Stem Cells; Humans; Male; Middle Aged; Nitric Oxide; Peptide Fragments; Phenotype; Reactive Oxygen Species; Renin-Angiotensin System

To investigate changes in the angiotensin converting enzyme 2 (ACE2) and angiotensin (1-7) [Ang (1-7)] and to explore the role of ACE2-Ang (1-7)-Mas receptor axis in hypertension with heart failure with preserved ejection fraction (HFPEF).
 Methods: A total of 70 patients with primary hypertension and preserved left ventricular ejection fraction (LVEF>50%) were recruited and patients were divided into a hypertension group (HBP) and a heart failure with preserved ejection fraction group (HFpEF) according to the diagnostic criteria of HFpEF. Thirty-five healthy participants were selected randomly as a control group. Enzyme linked immunosorbent assays (ELISA) method was used to detect concentration of Ang (1-7), ACE2, angiotensin II (Ang II), brain natriuretic peptide (BNP) in plasma. Male Sprague- Dawley (SD) rats was randomly divided into 2 groups: An HFpEF group (n=16) and a sham group (n=8). Rats (n=8) in the AAC group were given Ang (1-7) [0.5 mg/(kg.d), intraperitoneally] for 6 weeks, and the rest were given equal dose normal saline. Then all the rats were killed, and the hearts were taken out for hematoxylineosin (HE) staining. The protein expressions of angiotensin converting enzyme (ACE), ACE2, and Mas receptor were detected by Western blot.
 Results: The BNP and Ang II were significantly increased in the HBP group and the HFpEF group compared with the control group (P<0.01). There were not significantly different in levels of ACE2 and Ang (1-7) between the HBP group and control group (P>0.05), whereas those levels were significantly increased in the HFpEF group compared with the HBP group and control group (P<0.01). HE staining showed obvious hypertrophy of myocardial cell in the AAC group compared with the sham group. Hypertrophy of myocardial cell in the AAC+Ang (1-7) group was significantly higher than that in the AAC group. Expressions of ACE, ACE2, and Mas receptor proteins were significantly higher in the AAC group than those in the sham group (P<0.05), while the expressions of ACE2 and Mas receptor proteins in the AAC+Ang (1-7) group were significantly higher than those in the AAC group (P<0.05). There was no significant difference in the ACE protein expression between groups (P>0.05).
 Conclusion: ACE2 and Ang (1-7) are important predictive factors for the severity of heart failure and myocardial remodeling of HFpEF with hypertension; ACE2-Ang (1-7)-Mas receptor axis may play a protective role in preventing myocardial remodeling in HFpEF wi. 目的：探讨高血压射血分数保留心力衰竭(以下简称心衰)中血管紧张素转化酶(angiotensin converting enzyme，ACE)2、血管紧张素(1-7)[angiotensin (1-7)，Ang (1-7)]的变化及ACE2-Ang (1-7)-Mas受体轴在高血压射血分数保留心衰(heart failure with preserved ejection fraction，HFpEF)中的作用。方法：1)入选原发性高血压患者70例，心脏彩超检测左室射血分数(left ventricular ejection fraction，LVEF)≥50%，根据HFpEF的诊断标准将高血压患者分为单纯高血压(hypertension，HBP)组和高血压HFpEF组；同时入选35例健康体检者作为正常对照组(Control)。采用酶联免疫吸附测定法(enzyme linked immunosorbent assays，ELISA)检测各组血浆中ACE2，Ang (1-7)，血管紧张素II(angiotensin II，Ang II)及脑利钠肽(brain natriuretic peptide，BNP)水平。2)选取雄性SD大鼠24只，随机选取8只作为假手术组(Sham)，16只SD大鼠行腹主动脉缩窄术(abdominal aortic constriction，AAC)建立HFpEF模型组，后将HFpEF模型组SD大鼠随机分为两组(n=8)：一组于腹腔内注射Ang (1-7)0.5 mg/(kg.mg)作为Ang (1-7)干预组；另一组于腹腔内注射等剂量生理盐水(AAC组)。干预6周后处死所有大鼠，对心脏标本行苏木精-伊红(hematoxylineosin，HE)染色，采用Western印迹法测定心肌组织中ACE，ACE2及Mas受体蛋白表达水平。结果：HBP组及高血压HFpEF组的BNP和Ang II均较Control组明显增高(P<0.01)；HBP组的ACE2，Ang (1-7)与Control组比较，差异无统计学意义(P>0.05)，而高血压HFpEF组ACE2和Ang (1-7)较HBP组及Control组均明显升高(P<0.01)。HE染色结果显示AAC组的心肌细胞较Sham组明显肥大，而Ang (1-7)干预组的心肌细胞肥大程度较AAC组减轻，AAC组的ACE2，ACE及Mas受体蛋白表达水平较Sham组均明显升高(P<0.05)，Ang (1-7)干预组ACE2和Mas受体表达水平较AAC组明显升高(P<0.05)，而ACE表达水平未受影响(P>0.05)。结论：ACE2和Ang (1-7)参与高血压HFpEF的发生发展过程，对高血压HFpEF的心衰和心肌重构的严重程度有重要预测价值；ACE2-Ang (1-7)-Mas受体轴可能在抑制高血压HFpEF心肌重构中起保护作用。.

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme 2; Animals; Atrial Remodeling; Case-Control Studies; Enzyme-Linked Immunosorbent Assay; Heart Failure; Humans; Hypertension; Male; Peptide Fragments; Peptidyl-Dipeptidase A; Random Allocation; Rats; Rats, Sprague-Dawley; Receptors, G-Protein-Coupled; Stroke Volume; Ventricular Function, Left; Ventricular Remodeling

Cardiac sympathetic afferent reflex (CSAR) enhancement contributes to exaggerated sympathetic activation in chronic heart failure (CHF). The current study aimed to investigate the roles of angiotensin (Ang)-(1-7) in CSAR modulation and sympathetic activation and Ang-(1-7) signaling pathway in paraventricular nucleus of CHF rats.. CHF was induced by coronary artery ligation. Responses of renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) to epicardial application of capsaicin were used to evaluate CSAR in rats with anesthesia.. Ang-(1-7) increased RSNA, MAP, CSAR activity, cAMP level, NAD(P)H oxidase activity and superoxide anion level more significantly in CHF than in sham-operated rats, while Mas receptor antagonist A-779 had the opposite effects. Moreover, Ang-(1-7) augmented effects of Ang II in CHF rats. The effects of Ang-(1-7) were blocked by A-779, adenylyl cyclase inhibitor SQ22536, protein kinase A inhibitor Rp-cAMP, superoxide anion scavenger tempol and NAD(P)H oxidase inhibitor apocynin. Mas and AT1 receptor protein expressions, Ang-(1-7) and Ang II levels in CHF increased.. These results indicate that Ang-(1-7) in paraventricular nucleus enhances CSAR and sympathetic output not only by exerting its own effects but also by augmenting the effects of Ang II through Mas receptor in CHF. Endogenous Ang-(1-7)/Mas receptor activity contributes to CSAR enhancement and sympathetic activation in CHF, and NAD(P)H oxidase-derived superoxide anions and the cAMP-PKA signaling pathway are involved in mediating the effects of Ang-(1-7) in CHF.

Topics: Acetophenones; Angiotensin I; Angiotensin II; Animals; Arterial Pressure; Capsaicin; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Cyclic N-Oxides; Heart Failure; Hemodynamics; Kidney; Male; NADPH Oxidases; NG-Nitroarginine Methyl Ester; Paraventricular Hypothalamic Nucleus; Peptide Fragments; Rats; Rats, Sprague-Dawley; Signal Transduction; Spin Labels; Superoxides; Sympathetic Nervous System

The existence of a new cascade, angiotensin-converting enzyme (ACE) 2/angiotensin (Ang)-(1-7)/Mas receptor axis, has been recently established in the renin-angiotensin system. However, the dynamics of this cascade under various pathological conditions in clinical settings is still unclear. Forty-nine patients who underwent emergency hospitalization because of acute heart failure (AHF) consented to participate in this study. Thirty-eight healthy volunteers served as controls. Serum ACE activity, ACE2, Ang-(1-7) concentration, plasma Ang II, aldosterone concentration, and plasma renin activity (PRA) were measured at the acute stage. We conducted a comparative study between patients with AHF and healthy volunteers. Patients with AHF showed lower serum ACE activity and plasma aldosterone concentration than healthy volunteers (12.3 vs. 15.1 IU/L, respectively; P = 0.01, 75.6 vs. 125.3 pg/mL, respectively; P = 0.000); there were no differences between the two groups in PRA and plasma Ang II concentration. Patients with AHF had a higher serum ACE2 concentration than healthy volunteers (7.9 vs. 4.8 ng/mL, respectively; P = 0.002), but their serum Ang-(1-7) concentration was significantly lower (2.4 vs 3.1 ng/mL, respectively; P = 0.005). Patients with AHF had a higher serum ACE2 concentration, lower serum Ang-(1-7) concentration, and lower serum ACE activity and plasma aldosterone concentrations than healthy volunteers, whereas PRA and plasma Ang II concentration were the same.

Topics: Acute Disease; Adult; Aged; Aldosterone; Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme 2; Blood Pressure; Case-Control Studies; Emergencies; Female; Heart Failure; Hospitalization; Humans; Japan; Male; Middle Aged; Peptide Fragments; Peptidyl-Dipeptidase A; Regression Analysis; Renin; Renin-Angiotensin System

Patients with congestive heart failure (CHF) have increased hospital readmission rates and mortality if they are concomitantly diagnosed with cognitive decline and memory loss. Accordingly, we developed a preclinical model of CHF-induced cognitive impairment with the goal of developing novel protective therapies against CHF related cognitive decline. CHF was induced by ligation of the left coronary artery to instigate a myocardial infarction (MI). By 4- and 8-weeks post-MI, CHF mice had approximately a 50% and 70% decline in ejection fraction as measured by echocardiography. At both 4- and 8-weeks post-MI, spatial memory performance in CHF mice as tested using the Morris water task was significantly impaired as compared with sham. In addition, CHF mice had significantly worse performance on object recognition when compared with shams as measured by discrimination ratios during the novel object recognition NOR task. At 8-weeks post-MI, a subgroup of CHF mice were given Angiotensin (Ang)-(1-7) (50mcg/kg/hr) subcutaneously for 4 weeks. Following 3 weeks treatment with systemic Ang-(1-7), the CHF mice NOR discrimination ratios were similar to shams and significantly better than the performance of CHF mice treated with saline. Ang-(1-7) also improved spatial memory in CHF mice as compared with shams. Ang-(1-7) had no effect on cardiac function. Inflammatory biomarker studies from plasma revealed a pattern of neuroprotection that may underlie the observed improvements in cognition. These results demonstrate a preclinical mouse model of CHF that exhibits both spatial memory and object recognition dysfunction. Furthermore, this CHF-induced cognitive impairment is attenuated by treatment with systemic Ang-(1-7). (PsycINFO Database Record

Topics: Angiotensin I; Animals; Cognitive Dysfunction; Disease Models, Animal; Heart Failure; Inflammation; Male; Maze Learning; Mice; Mice, Inbred C57BL; Myocardial Infarction; Peptide Fragments; Ventricular Remodeling; Visual Acuity

Obesity is increasing in prevalence and is strongly associated with metabolic and cardiovascular disorders. The renin-angiotensin system (RAS) has emerged as a key pathogenic mechanism for these disorders; angiotensin (Ang)-converting enzyme 2 (ACE2) negatively regulates RAS by metabolizing Ang II into Ang 1-7. We studied the role of ACE2 in obesity-mediated cardiac dysfunction. ACE2 null (ACE2KO) and wild-type (WT) mice were fed a high-fat diet (HFD) or a control diet and studied at 6 months of age. Loss of ACE2 resulted in decreased weight gain but increased glucose intolerance, epicardial adipose tissue (EAT) inflammation, and polarization of macrophages into a proinflammatory phenotype in response to HFD. Similarly, human EAT in patients with obesity and heart failure displayed a proinflammatory macrophage phenotype. Exacerbated EAT inflammation in ACE2KO-HFD mice was associated with decreased myocardial adiponectin, decreased phosphorylation of AMPK, increased cardiac steatosis and lipotoxicity, and myocardial insulin resistance, which worsened heart function. Ang 1-7 (24 µg/kg/h) administered to ACE2KO-HFD mice resulted in ameliorated EAT inflammation and reduced cardiac steatosis and lipotoxicity, resulting in normalization of heart failure. In conclusion, ACE2 plays a novel role in heart disease associated with obesity wherein ACE2 negatively regulates obesity-induced EAT inflammation and cardiac insulin resistance.

Topics: Adiponectin; Adipose Tissue; AMP-Activated Protein Kinases; Angiotensin I; Angiotensin-Converting Enzyme 2; Animals; Blood Glucose; Blotting, Western; Diet, High-Fat; Enzyme-Linked Immunosorbent Assay; Glucose Intolerance; Heart; Heart Failure; Humans; Inflammation; Insulin Resistance; Macrophages; Mice; Mice, Knockout; Myocardium; Obesity; Oxidative Stress; Peptide Fragments; Peptidyl-Dipeptidase A; Pericardium; Phosphorylation; Real-Time Polymerase Chain Reaction; Stroke Volume; Tumor Necrosis Factor-alpha; Vasodilator Agents; Weight Gain

The detailed mechanisms determining the course of congestive heart failure (CHF) in hypertensive subjects with associated renal dysfunction remain unclear. In Ren-2 transgenic rats (TGR), a model of angiotensin II (ANG II)-dependent hypertension, CHF was induced by volume overload achieved by creation of the aorto-caval fistula (ACF). In these rats we investigated the putative pathophysiological contribution of epoxyeicosatrienoic acids (EETs) and compared it with the role of the renin-angiotensin system (RAS). We found that untreated ACF TGR exhibited marked intrarenal and myocardial deficiency of EETs and impairment of renal function. Chronic treatment of these rats with cis-4-[4-(3-adamantan-1-yl-ureido)cyclohexyloxy]benzoic acid (c-AUCB, 3 mg/L in drinking water), an inhibitor of soluble epoxide hydrolase (sEH) which normally degrades EETs, increased intrarenal and myocardial EETs, markedly improved survival rate, and increased renal blood flow, glomerular filtration rate and fractional sodium excretion, without altering RAS activity. Chronic angiotensin-converting enzyme inhibition (ACEi) with trandolapril, (6 mg/L in drinking water) improved survival rate even more, and also inhibited the development of renal dysfunction; these beneficial actions were associated with significant suppression of the vasoconstrictor/sodium retaining axis and further activation of the vasodilatory/natriuretic axis of the systemic and intrarenal RAS, without modifying tissue availability of biologically active fatty acid epoxides. In conclusion, these findings strongly suggest that chronic sEH inhibition and chronic treatment with ACEi, each of them altering a different vasoactive system, delay or even prevent the onset of decompensation of CHF in ACF TGR, probably by preventing the development of renal dysfunction.

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Animals; Aorta; Blood Pressure; Cytochrome P-450 Enzyme System; Disease Progression; Enzyme Inhibitors; Epoxide Hydrolases; Fatty Acids, Monounsaturated; Female; Fistula; Heart Failure; Heart Rate; Hemodynamics; Kidney; Male; Peptide Fragments; Rats; Rats, Transgenic; Renin; Renin-Angiotensin System; Solubility; Time Factors; Vena Cava, Inferior

ACE2-Ang (1-7) axis is a key regulator in cardiac hypertrophy, myocardial remodeling and development of heart failure. To investigate how ACE2-Ang (1-7) axis function in pressure-overload-induced heart failure, male SD rats (weighing about 250 g) were used to establish the model of pressure-overload-induced heart failure using aortic stenosis surgery. The level of plasma ACE2, ACE and Ang (1-7) from heart failure group were significantly up-regulated compared with the sham group by ELISA test. The mRNA and protein expression of ACE2 in myocardial tissue from heart failure group also showed remarkably increased. Importantly, we found that the expression of ACE2 and Ang (1-7) were reversed in heart failure group after treatment with AT1 receptor antagonist telmisartan. Compared with heart failure group, the level of plasma ACE2, ACE and Ang (1-7) were significantly decreased in telmisartan treated group. The mRNA and protein expression of ACE2 in cardiac tissue from telmisartan group was also significantly decreased, while Mas mRNA and protein level was increased. Taken together, these studies demonstrated that the expression of ACE2-Ang (1-7) axis was induced in pressure-overload-induced heart failure model, suggesting that ACE2-Ang (1-7) axis may have a protective role in the development of heart failure and may provide a new target for drug development of heart failure.

Topics: Angiotensin I; Angiotensin-Converting Enzyme 2; Animals; Blotting, Western; Disease Models, Animal; Enzyme-Linked Immunosorbent Assay; Heart Failure; Male; Myocardium; Peptide Fragments; Peptidyl-Dipeptidase A; Rats; Rats, Sprague-Dawley; Real-Time Polymerase Chain Reaction

The detailed mechanisms determining the course of congestive heart failure (CHF) and associated renal dysfunction remain unclear. In a volume overload model of CHF induced by creation of aorto-caval fistula (ACF) in Hannover Sprague-Dawley (HanSD) rats we explored the putative pathogenetic contribution of epoxyeicosatrienoic acids (EETs), active products of CYP-450 dependent epoxygenase pathway of arachidonic acid metabolism, and compared it with the role of the renin-angiotensin system (RAS). Chronic treatment with cis-4-[4-(3-adamantan-1-yl-ureido) cyclohexyloxy]benzoic acid (c-AUCB, 3 mg/l in drinking water), an inhibitor of soluble epoxide hydrolase (sEH) which normally degrades EETs, increased intrarenal and myocardial EETs to levels observed in sham-operated HanSD rats, but did not improve the survival or renal function impairment. In contrast, chronic angiotensin-converting enzyme inhibition (ACEi, trandolapril, 6 mg/l in drinking water) increased renal blood flow, fractional sodium excretion and markedly improved survival, without affecting left ventricular structure and performance. Hence, renal dysfunction rather than cardiac remodeling determines long-term mortality in advanced stage of CHF due to volume overload. Strong protective actions of ACEi were associated with suppression of the vasoconstrictor/sodium retaining axis and activation of vasodilatory/natriuretic axis of the renin-angiotensin system in the circulating blood and kidney tissue.

Topics: 8,11,14-Eicosatrienoic Acid; Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Animals; Benzoates; Disease Models, Animal; Drug Evaluation, Preclinical; Epoxide Hydrolases; Epoxy Compounds; Heart Failure; Kidney; Male; Myocardium; Peptide Fragments; Random Allocation; Rats; Renal Insufficiency; Renin-Angiotensin System; Ultrasonography; Urea

Recent evidence has shown that, in heart failure (HF), clinically relevant concentrations of angiotensin-(1-7) [Ang-(1-7)] counteracts angiotensin II induced cardiac depression and produces positive inotropic effects in both left ventricle (LV) and myocytes. However, the underlying electrophysiological mechanism is unclear. We investigated the role and mechanism of Ang-(1-7) on LV myocyte L-type calcium current (ICa,L) responses in normal state and in HF.. We compared the effect of Ang-(1-7) (10(-5) M) on ICa,L responses in isolated LV myocytes obtained from 11 rats with isoproterenol (ISO) induced HF (3 months after 170 mg/kg subcutaneous for 2 days) and from 8 age-matched normal control rats by patch clamp technique.. In normal myocytes, compared with baseline, superfusion of Ang-(1-7) caused no significant changes in ICa,L (8.2 ± 0.2 versus 8.0 ± 0.3 pA/pF, p= not significant). In HF myocytes, the baseline ICa,L was significantly reduced (5.3 ± 0.1 versus 8.0 ± 0.3 pA/pF, p < 0.01). Ang-(1-7) produced a 21% increase in ICa,L (6.4±0.1 versus 5.3±0.1 pA/pF, p < 0.01). Pretreatment of HF myocytes with a nitric oxide (NO) synthase inhibitor (L-NAME, 10(-5) M) resulted in a significantly greater increase in ICa,L (28%, 8.4 ± 0.1 versus 6.5 ± 0.1 pA/pF, p < 0.01) during Ang-(1-7) superfusion. In contrast, during incubation with the bradykinin (BK) inhibitor HOE 140 (10(-6) M), Ang-(1-7) induced increase in ICa,L was significantly decreased. The Ang-(1-7) induced increase in ICa,L was abolished by [D-Ala(7)]-Ang-(1-7) (A-779, 10(-5) M).. HF alters the response of ICa,L to Ang-(1-7). In normal myocytes, Ang-(1-7) has no significant effect on ICa,L. However, in HF myocytes, Ang-(1-7) increases ICa,L. These effects are mediated by the Ang-(1-7) Mas receptors and involve activation of NO/BK pathways.

Topics: Angiotensin I; Animals; Bradykinin; Calcium Channels, L-Type; Calcium Signaling; Cardiotonic Agents; Disease Models, Animal; Heart Failure; Isoproterenol; Male; Membrane Potentials; Myocytes, Cardiac; Necrosis; Nitric Oxide; Peptide Fragments; Proto-Oncogene Mas; Proto-Oncogene Proteins; Rats, Sprague-Dawley; Receptors, G-Protein-Coupled; Time Factors; Ventricular Function, Left

The midbrain periaqueductal gray (PAG) is an integrative neural site in regulating several physiological functions including cardiovascular activities driven by sympathetic nervous system. Specifically, activation of the dorsolateral PAG (dl-PAG) leads to increases in sympathetic nervous activity and arterial blood pressure. Our recent studies demonstrated that angiotensin-(1-7) [Ang-(1-7)] plays an inhibitory role in neuronal activity of the dl-PAG via a Mas-R [Ang-(1-7) receptor] and neuronal NO dependent signaling pathway (Mas-R-nNOS). Because sympathetic nervous activity is augmented in chronic heart failure (HF), the present study was to determine (1) the levels of Ang-(1-7) and Mas-R-nNOS expression within the dl-PAG of control rats and rats with HF and (2) the role for Ang-(1-7) in modulating activity of dl-PAG neurons in both groups. Results showed that chronic HF decreased the levels of Ang-(1-7) and attenuated Mas-R-nNOS pathways. Also, we demonstrated that the discharge rates of dl-PAG neurons of HF rats (5.52 ± 0.52 Hz, n=21, P<0.05 vs. control) were augmented as compared with control rats (4.03 ± 0.39 Hz, n=28) and an inhibitory role played by Ang-(1-7) in neuronal activity of the dl-PAG was significantly decreased in HF (51 ± 6%, P<0.05 vs. control) as compared with controls (72 ± 8%). Our findings suggest that the inhibitory effects of Ang-(1-7) on dl-PAG neurons are impaired in HF, likely due to attenuated Mas-R-nNOS signaling pathways.

Topics: Angiotensin I; Animals; Chronic Disease; Heart Failure; Male; Neurons; Nitric Oxide Synthase Type I; Peptide Fragments; Periaqueductal Gray; Rats, Sprague-Dawley; Receptors, Angiotensin; Signal Transduction

Angiotensin converting enzyme 2 (ACE2) is a negative regulator of the renin-angiotensin system (RAS), catalyzing the conversion of Angiotensin II to Angiotensin 1-7. Apelin is a second catalytic substrate for ACE2 and functions as an inotropic and cardioprotective peptide. While an antagonistic relationship between the RAS and apelin has been proposed, such functional interplay remains elusive. Here we found that ACE2 was downregulated in apelin-deficient mice. Pharmacological or genetic inhibition of angiotensin II type 1 receptor (AT1R) rescued the impaired contractility and hypertrophy of apelin mutant mice, which was accompanied by restored ACE2 levels. Importantly, treatment with angiotensin 1-7 rescued hypertrophy and heart dysfunctions of apelin-knockout mice. Moreover, apelin, via activation of its receptor, APJ, increased ACE2 promoter activity in vitro and upregulated ACE2 expression in failing hearts in vivo. Apelin treatment also increased cardiac contractility and ACE2 levels in AT1R-deficient mice. These data demonstrate that ACE2 couples the RAS to the apelin system, adding a conceptual framework for the apelin-ACE2-angiotensin 1-7 axis as a therapeutic target for cardiovascular diseases.

Topics: Adipokines; Angiotensin I; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme 2; Animals; Apelin; Apelin Receptors; Feedback, Physiological; Gene Expression Regulation; Heart Failure; Intercellular Signaling Peptides and Proteins; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Myocardial Contraction; Peptide Fragments; Peptidyl-Dipeptidase A; Promoter Regions, Genetic; ras Proteins; Receptor, Angiotensin, Type 1; Receptors, G-Protein-Coupled; Recombinant Fusion Proteins; Renin-Angiotensin System; Signal Transduction

Angiotensin-converting enzyme 2 (ACE-2) is a membrane-associated carboxy-peptidase catalyzes the conversion of the vasoconstrictor angiotensin (ANG)-II to the vasodilatory peptide ANG 1-7. In view of the expanding axis of the renin angiotensin system, we have investigated the cardioprotective effects of olmesartan (10mg/kg/day) in experimental autoimmune myocarditis. Olmesartan treatment effectively suppressed the myocardial protein expressions of inflammatory markers in comparison to the vehicle-treated rats. However, the protein and mRNA levels of ACE-2 and ANG 1-7, and its receptor Mas were upregulated in olmesartan treated group compared to vehicle-treated rats. Olmesartan medoxomil treatment significantly decreased the expression levels of phospho-p38 mitogen-activated protein kinase (MAPK), phospho-JNK, phospho-ERK and phospho-(MAPK) activated protein kinase-2 than with those of vehicle-treated rats. Moreover, vehicle-treated rats were shown to be up-regulated protein expressions of NADPH oxidase subunits (p47phox, p67phox and Nox-4), myocardial apoptotic markers and endoplasmic reticulum stress markers in comparison to those of normal and all these effects are expectedly down-regulated by an olmesartan. In addition, attenuated protein levels of phosphatidylinositol-3-kinase (PI3K) and phospho-Akt in the vehicle-treated EAM rats were prevented by olmesartan treatment. Our results suggest that beneficial effects of olmesartan treatment was more effective therapy in combating the inflammation, oxidative stress, apoptosis and signaling pathways associated with heart failure at least in part via the modulation of ANG 1-7 mas receptor.

Topics: Angiotensin I; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme 2; Animals; Apoptosis; Autoimmune Diseases; Cardiotonic Agents; Endoplasmic Reticulum Stress; Heart Failure; Imidazoles; Inflammation; JNK Mitogen-Activated Protein Kinases; Membrane Glycoproteins; Myocarditis; NADPH Oxidase 4; NADPH Oxidases; Oxidative Stress; p38 Mitogen-Activated Protein Kinases; Peptide Fragments; Peptidyl-Dipeptidase A; Phosphatidylinositol 3-Kinases; Phosphoproteins; Proto-Oncogene Proteins c-akt; Rats; Rats, Inbred Lew; Receptor, Angiotensin, Type 1; Receptors, Interleukin-1; RNA, Messenger; Tetrazoles

Loss of angiotensin (Ang)-converting enzyme 2 (ACE2) and inability to metabolize Ang II to Ang 1-7 perpetuate the actions of Ang II after biomechanical stress and exacerbate early adverse myocardial remodeling. Ang receptor blockers are known to antagonize the effect of Ang II by blocking Ang II type 1 receptor (AT(1)R) and also by upregulating the ACE2 expression. We directly compare the benefits of AT(1)R blockade versus enhancing Ang 1-7 action in pressure-overload-induced heart failure in ACE2 knockout mice. AT(1)R blockade and Ang 1-7 both resulted in marked recovery of systolic dysfunction in pressure-overloaded ACE2-null mice. Similarly, both therapies attenuated the increase in NADPH oxidase activation by downregulating the expression of Nox2 and p47(phox) subunits and also by limiting the p47(phox) phosphorylation. Biomechanical stress-induced increase in protein kinase C-α expression and phosphorylation of extracellular signal-regulated kinase 1/2, signal transducer and activator of transcription 3, Akt, and glycogen synthase kinase 3β were normalized by irbesartan and Ang 1-7. Ang receptor blocker and Ang 1-7 effectively reduced matrix metalloproteinase 2 activation and matrix metalloproteinase 9 levels. Ang II-mediated cellular effects in cultured adult cardiomyocytes and cardiofibrolasts isolated from pressure-overloaded ACE2-null hearts were inhibited to similar degree by AT(1)R blockade and stimulation with Ang 1-7. Thus, treatment with the AT(1)R blocker irbesartan and Ang 1-7 prevented the cardiac hypertrophy and improved cardiac remodeling in pressure-overloaded ACE2-null mice by suppressing NADPH oxidase and normalizing pathological signaling pathways.

Topics: Angiotensin I; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme 2; Animals; Antihypertensive Agents; Biphenyl Compounds; Blood Pressure; Blotting, Western; Cardiotonic Agents; Cells, Cultured; Drug Synergism; Enzyme Activation; Female; Heart; Heart Failure; Irbesartan; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Myocardium; NADPH Oxidases; Peptide Fragments; Peptidyl-Dipeptidase A; Reverse Transcriptase Polymerase Chain Reaction; Superoxides; Systole; Tetrazoles

Angiotensin-converting enzyme 2 (ACE2) is an important negative regulator of the renin-angiotensin system. Loss of ACE2 enhances the susceptibility to heart disease but the mechanism remains elusive. We hypothesized that ACE2 deficiency activates the NADPH oxidase system in pressure overload-induced heart failure.. Using the aortic constriction model, we subjected wild-type (Ace2(+/y)), ACE2 knockout (ACE2KO, Ace2(-/y)), p47(phox) knockout (p47(phox)KO, p47(phox-)(/-)), and ACE2/p47(phox) double KO mice to pressure overload. We examined changes in peptide levels, NADPH oxidase activity, gene expression, matrix metalloproteinases (MMP) activity, pathological signalling, and heart function. Loss of ACE2 resulted in enhanced susceptibility to biomechanical stress leading to eccentric remodelling, increased pathological hypertrophy, and worsening of systolic performance. Myocardial angiotensin II (Ang II) levels were increased, whereas Ang 1-7 levels were lowered. Activation of Ang II-stimulated signalling pathways in the ACE2-deficient myocardium was associated with increased expression and phosphorylation of p47(phox), NADPH oxidase activity, and superoxide generation, leading to enhanced MMP-mediated degradation of the extracellular matrix. Additional loss of p47(phox) in the ACE2KO mice normalized the increased NADPH oxidase activity, superoxide production, and systolic dysfunction following pressure overload. Ang 1-7 supplementation suppressed the increased NADPH oxidase and rescued the early dilated cardiomyopathy in pressure-overloaded ACE2KO mice.. In the absence of ACE2, biomechanical stress triggers activation of the myocardial NAPDH oxidase system with a critical role of the p47(phox) subunit. Increased production of superoxide, activation of MMP, and pathological signalling leads to severe adverse myocardial remodelling and dysfunction in ACE2KO mice.

Topics: Analysis of Variance; Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme 2; Animals; Blood Pressure; Cardiomyopathy, Dilated; Disease Models, Animal; Enzyme Activation; Extracellular Matrix; Heart Failure; Male; Matrix Metalloproteinases; Mice; Mice, Inbred C57BL; Mice, Knockout; Myocardium; NADPH Oxidases; Oxidative Stress; Peptide Fragments; Peptidyl-Dipeptidase A; Phosphorylation; Stress, Mechanical; Superoxides; Time Factors; Ventricular Function, Left; Ventricular Remodeling

In chronic heart failure (CHF), arterial baroreflex function is impaired, in part, by activation of the central renin-angiotensin system. A metabolite of angiotensin (Ang) II, Ang-(1-7), has been shown to exhibit cardiovascular effects that are in opposition to that of Ang II. However, the action of Ang-(1-7) on sympathetic outflow and baroreflex function is not well understood, especially in CHF. The aim of this study was to determine the effect of intracerebroventricular infusion of Ang-(1-7) on baroreflex control of heart rate and renal sympathetic nerve activity in conscious rabbits with CHF. We hypothesized that central Ang-(1-7) would improve baroreflex function in CHF. Ang-(1-7) (2 nmol/1 μL per hour) or artificial cerebrospinal fluid (1 μL per hour) was infused by an osmotic minipump for 4 days in sham and pacing-induced CHF rabbits (n=3 to 6 per group). Ang-(1-7) treatment had no effects in sham rabbits but reduced heart rate and increased baroreflex gain (7.4±1.5 versus 2.5±0.4 bpm/mm Hg; P<0.05) in CHF rabbits. The Ang-(1-7) antagonist A779 (8 nmol/1 μL per hour) blocked the improvement in baroreflex gain in CHF. Baroreflex gain increased in CHF+Ang-(1-7) animals when only the vagus was allowed to modulate baroreflex control by acute treatment with the β-1 antagonist metoprolol, indicating increased vagal tone. Baseline renal sympathetic nerve activity was significantly lower, and baroreflex control of renal sympathetic nerve activity was enhanced in CHF rabbits receiving Ang-(1-7). These data suggest that augmentation of central Ang-(1-7) inhibits sympathetic outflow and increases vagal outflow in CHF, thus contributing to enhanced baroreflex gain in this disease state.

Topics: Angiotensin I; Angiotensin II; Animals; Antihypertensive Agents; Baroreflex; Chronic Disease; Consciousness; Disease Models, Animal; Heart Failure; Heart Rate; Infusions, Intraventricular; Kidney; Male; Metoprolol; Peptide Fragments; Rabbits; Sympathetic Nervous System; Vagus Nerve

Angiotensin-converting enzyme-2 (ACE-2) is a homolog of ACE that preferentially forms angiotensin-(ANG)-1-7 from angiotensin II (ANG II). We investigated the cardioprotective effects of telmisartan, a well-known angiotensin receptor blockers (ARBs) against experimental autoimmune myocarditis (EAM). EAM was induced in Lewis rats by immunization with porcine cardiac myosin. The rats were divided into two groups and treated with telmisartan (10 mg/kg/day) or vehicle for 21 days. Myocardial functional parameters were significantly improved by treatment with telmisartan compared with vehicle-treated rats. Telmisartan lowered myocardial protein expressions of NADPH oxidase subunits 3-nitrotyrosine, p47phox, p67 phox, Nox-4 and superoxide production significantly than vehicle-treated rats. In contrast myocardial protein levels of ACE-2, ANG 1-7 mas receptor were upregulated in the telmisartan treated group compared with those of vehicle-treated rats. The myocardial protein expression levels of tumor necrosis factor receptor (TNFR)-associated factor (TRAF)-2, C/EBP homologous protein (CHOP) and glucose-regulated protein (GRP) 78 were decreased in the telmisartan treated rats compared with those of vehicle-treated rats. In addition, telmisartan treatment significantly decreased the protein expression levels of phospho-p38 mitogen-activated protein kinase (MAPK), phospho-JNK, phospho-ERK and phospho (MAPK) activated protein kinase-2 than with those of vehicle-treated rats. Moreover, telmisartan significantly decreased the production of proinflammatory cytokines, myocardial apoptotic markers and caspase-3 positive cells compared with those of vehicle-treated rats. Therefore, we suggest that telmisartan was beneficial protection against heart failure in rats, at least in part by suppressing inflammation, oxidative stress, ER stress as well as signaling pathways through the modulation of ACE2/ANG1-7/Mas receptor axis.

Topics: Angiotensin I; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme 2; Animals; Apoptosis; Benzimidazoles; Benzoates; Biomarkers; Cytokines; Disease Models, Animal; Endoplasmic Reticulum; Heart Failure; Male; Mitogen-Activated Protein Kinases; Myocarditis; NADPH Oxidases; Oxidative Stress; Peptide Fragments; Peptidyl-Dipeptidase A; Protective Agents; Protein Subunits; Rats; Signal Transduction; Superoxides; Telmisartan

To investigate the possible effects of telmisartan and losartan on cardiac function in adriamycin (ADR)-induced heart failure in rats, and to explore the changes in plasma level of angiotensin-(1-7)[Ang-(1-7)] and myocardial expression of angiotensin II type 1/2 receptors (AT(1)R / AT(2)R) and Mas receptor caused by the two drugs.. Male Sprague-Dawley rats were randomly divided into 4 groups: the control group, ADR-treated heart failure group (ADR-HF), telmisartan plus ADR-treated group (Tel+ADR) and losartan plus ADR-treated group (Los+ADR). ADR was administrated (2.5 mg/kg, ip, 6 times in 2 weeks). The rats in the Tel+ADR and Los+ADR groups were treated orally with telmisartan (10 mg/kg daily po) and losartan (30 mg/kg daily), respectively, for 6 weeks. The plasma level of Ang-(1-7) was determined using ELISA. The mRNA and protein expression of myocardial Mas receptor, AT(1)R and AT(2)R were measured using RT-PCR and Western blotting, respectively.. ADR significantly reduced the plasma level of Ang-(1-7) and the expression of myocardial Mas receptor and myocardial AT(2)R, while significantly increased the expression of myocardial AT(1)R. Treatment with telmisartan and losartan effectively increased the plasma level of Ang-(1-7) and suppressed myocardial AT(1)R expression, but did not influence the expression of Mas receptor and AT(2)R.. The protective effects of telmisartan and losartan in ADR-induced heart failure may be partially due to regulation of circulating Ang-(1-7) and myocardial AT(1)R expression.

Topics: Angiotensin I; Angiotensin II Type 1 Receptor Blockers; Animals; Antibiotics, Antineoplastic; Benzimidazoles; Benzoates; Doxorubicin; Gene Expression Regulation; Heart; Heart Failure; Losartan; Male; Myocardium; Peptide Fragments; Rats; Rats, Sprague-Dawley; Receptor, Angiotensin, Type 1; Telmisartan

Angiotensin-converting enzyme 2 (ACE2) has been suggested to be involved in the central regulation of autonomic function. During chronic heart failure (CHF), elevated central angiotensin II signaling contributes to the sustained increase of sympathetic outflow. This is accompanied by a downregulation of ACE2 in the brain. We hypothesized that central overexpression of ACE2 decreases sympathetic outflow and enhances baroreflex function in CHF. Transgenic mice overexpressing human ACE2 selectively in the brain (SYN-hACE2 [SA]) and wild-type littermates (WT) were used. CHF was induced by permanent coronary artery ligation. Four weeks after coronary artery ligation, both WT and SA mice exhibited a significant decrease in left ventricular ejection fraction (<40%). A slight decrease in mean arterial pressure was found only in SA mice. Compared with WT mice with CHF, brain-selective ACE2 overexpression attenuated left ventricular end-diastolic pressure; decreased urinary norepinephrine excretion; baseline renal sympathetic nerve activity (WT CHF: 71.6±7.6% max versus SA CHF: 49.3±6.1% max); and enhanced baroreflex sensitivity (maximum slope: WT sham: 1.61±0.16%/mm Hg versus SA CHF: 1.51±0.17%/mm Hg). Chronic subcutaneous blockade of mas receptor increased renal sympathetic nerve activity in SA mice with CHF (A779: 67.3±5.8% versus vehicle: 46.4±3.6% of max). An upregulation in angiotensin II type 1 receptor expression was detected in medullary nuclei in WT CHF mice, which was significantly attenuated in SA mice with CHF. These data suggest that central ACE2 overexpression exerts a potential protective effect in CHF through attenuating sympathetic outflow. The mechanism for this effect involves angiotensin (1-7) mas signaling, as well as a decrease in angiotensin II type 1 receptor signaling in the medulla.

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme 2; Animals; Baroreflex; Enzyme Induction; Heart Failure; Humans; Male; Medulla Oblongata; Mice; Mice, Knockout; Myocardial Ischemia; Nerve Tissue Proteins; Nitric Oxide; Norepinephrine; Organ Specificity; Peptide Fragments; Peptidyl-Dipeptidase A; Proto-Oncogene Mas; Proto-Oncogene Proteins; Receptors, Angiotensin; Receptors, G-Protein-Coupled; Recombinant Fusion Proteins; Reflex, Abnormal; Sympathetic Nervous System

Angiotensin (Ang)-(1-7) attenuates the development of heart failure. In addition to its local effects on cardiovascular tissue, Ang-(1-7) also stimulates bone marrow, which harbors cells that might complement the therapeutic effect of Ang-(1-7). We studied the effects of Ang-(1-7) either produced locally in the heart or subcutaneously injected during the development of heart failure induced by myocardial infarction (MI) and explored the role of cardiovascular progenitor cells in promoting the effects of this heptapeptide.. Effects of Ang-(1-7) on bone marrow-derived mononuclear cells in rodents, particularly endothelial progenitor cells, were investigated in vitro and in vivo in rats, in mice deficient for the putative Ang-(1-7) receptor Mas, and in mice overexpressing Ang-(1-7) exclusively in the heart. Three weeks after MI induction through permanent coronary artery occlusion, effects of Ang-(1-7) either produced locally in the heart or injected into the subcutaneous space were investigated. Ang-(1-7) stimulated proliferation of endothelial progenitor cells isolated from sham or infarcted rodents. The stimulation was blunted by A779, a Mas receptor blocker, or by Mas deficiency. Infusion of Ang-(1-7) after MI increased the number of c-kit- and vascular endothelial growth factor-positive cells in infarcted hearts, inhibited cardiac hypertrophy, and improved cardiac function 3 weeks after MI, whereas cardiomyocyte-derived Ang-(1-7) had no effect.. Our data suggest circulating rather than cardiac Ang-(1-7) to be beneficial after MI. This beneficial effect correlates with a stimulation of cardiac progenitor cells in vitro and in vivo. This characterizes the heptapeptide as a promising new tool in stimulating cardiovascular regeneration under pathophysiological conditions.

Topics: Analysis of Variance; Angiotensin I; Angiotensin II; Animals; Bone Marrow Cells; Heart Failure; Hemodynamics; Immunohistochemistry; Mice; Mice, Inbred C57BL; Mice, Knockout; Myocardial Infarction; Myocytes, Cardiac; Peptide Fragments; Proto-Oncogene Proteins c-kit; Rats; Rats, Sprague-Dawley; Rats, Wistar; Reverse Transcriptase Polymerase Chain Reaction; Vascular Endothelial Growth Factor A

The renin-angiotensin system (RAS) plays a critical role in chronic renal failure associated with heart failure. In the past few years, angiotensin (Ang) (1-7) have been reported to counteract the effects of angiotensin II (Ang II) and were even considered as a new therapeutical target in RAS. The purposes of this study were to examine whether the Ang (1-7) improves the heart function and remodeling of the left ventricle (LV) in mice with 5/6 nephrectomy (NC). We used a 5/6 nephrectomy to induce significant renal dysfunction in wildtype mice (WT). Twelve weeks after NC, WT showed high blood pressure, significant left-ventricular dilation and dysfunction, which were accompanied by cardiomyocyte hypertrophy, diffuse interstitial fibrosis and oxidative damage of cardiomyocytes. Exogenous Ang (1-7) injection improved the heart function and remodeling of LV in mice with 5/6 NC accompanied by a reduction in cardiac interstitial fibrosis, inflammatory cytokine expression and oxidative damage levels of cardiomyocytes, decrease in the profibrotic signaling molecule transforming growth factor (TGF)-beta and increase in the collagen degradation signaling molecule matrix metalloproteinase (MMP)-2, -9. However, these beneficial effects did not occur in hydralazine-treated mice. These findings suggest that (1) Exogenous Ang (1-7) injection improve the heart function and remodeling of LV in mice with 5/6 NC. (2) These beneficial effects are independent of its anti-blood pressure effect.

Topics: Angiotensin I; Animals; Antihypertensive Agents; Blood Pressure; Creatinine; Heart Failure; Heart Ventricles; Kidney; Kidney Failure, Chronic; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Mice; Mice, Inbred C57BL; Myocardium; Peptide Fragments; Proto-Oncogene Mas; Proto-Oncogene Proteins; Receptors, G-Protein-Coupled; Transforming Growth Factor beta; Ventricular Dysfunction, Left; Ventricular Remodeling

The influence of hypotonic solution on cell volume and electrophysiology properties of the failing heart of cardiomyopathic hamsters (TO-2) was investigated. The results showed an increase in cell volume of quiescent isolated ventricular myocytes by 66% within 30 min. Angiotensin (1-7) [Ang (1-7)] (10(-8) M) administered to isotonic solution, elicited a gradual decline in cell volume and a significant decrease of the swelling-activated chloride current (I (Clswell)). The effect of Ang (1-7) on cell volume was inhibited by ouabain (10(-7) M). Angiotensin II (10(-8) M) caused cell swelling and increased I (Clswell). Experiments performed on isolated left ventricles of cardiomyopathic hamsters at an advanced stage of the disease, indicated that hypotonic solution prepared by diluting the normal Krebs solution by 25%, showed a gradual decrease of conduction velocity, generation of early after depolarizations and block of impulse conduction within 10 min. Implications to myocardial ischemia are discussed.

Topics: Angiotensin I; Angiotensin II; Animals; Arrhythmias, Cardiac; Cardiomyopathies; Cell Size; Cells, Cultured; Cricetinae; Electrophysiology; Heart Conduction System; Heart Failure; Heart Ventricles; Hypotonic Solutions; Male; Membrane Potentials; Myocytes, Cardiac; Peptide Fragments; Pulse

Angiotensin II (Ang II) and endothelin-1 (ET-1) share their effects on growth of myocardial cells but have been shown to elicit different effects on myocardial function. However, these effects vary markedly among species, cardiac regions (atrium or ventricle) and failing or non-failing myocardium. We therefore investigated the effects of both peptides on contractile function of isolated human myocytes from failing and non-failing hearts.. Cardiomyocytes were enzymatically isolated and electrically stimulated (15 V, 0.2 Hz). Ang II elicited a positive inotropic effect (PIE) mediated by activation of protein kinase C (PKC) in atrial but no effect in ventricular myocytes. ET-1 (10(-8) M) increased cell-shortening by 146+/-9.3% (p<0.05) in atrial myocytes, by 99.1+/-16.5% (p<0.05) in non-failing ventricular but only by 40.5+/-6.4% (p<0.05) in failing ventricular myocytes. The PIE of ET-1 in failing myocytes was more pronounced at low extracellular pH (+112.6+/-27% at pH 7.0 vs. +40.5+/-6.4% at pH 7.4, p<0.05). Amiloride, a sodium-hydrogen-exchange inhibitor, inhibited two thirds of the PIE of ET-1 in failing myocytes. The PKC-inhibitor decreased the PIE by 50% from 113% to 64% in ventricular myocytes under acidotic conditions.. Ang II and ET-1 elicited PIE in atrial myocytes, whereas in ventricular myocytes Ang II did not induce PIE in contrast to ET-1. The PIE of ET-1 was markedly attenuated in failing myocytes. Under acidotic conditions, the PIE of ET-1 was more pronounced in failing myocytes, indicating that ET-1 may activate signaling processes in failing myocytes, which are not activated in normal myocytes.

Topics: Angiotensin I; Endothelin-1; Female; Heart Failure; Humans; Male; Middle Aged; Muscle Contraction; Myocytes, Cardiac

We hypothesized that angiotensin-converting enzyme inhibition (ACE-I) during left ventricular assist device (LVAD) support in patients with end-stage heart failure prevents potentially deleterious effects on the extracellular matrix.. Left ventricular assist device-induced mechanical unloading increases myocardial collagen and stiffness and may contribute to the low rate of recovery.. Heart samples obtained before and after LVAD implantation were divided into groups depending on whether the patients received (n = 7) or did not receive (control; n = 15) ACE-I. At transplant, ex vivo pressure-volume relationships were measured and chamber and myocardial stiffness constants determined. Myocardial tissue content of angiotensin (Ang) I and II, matrix metalloproteinase (MMP)-1, tissue inhibitor of MMPs (TIMP)-1, and total and cross-linked collagen was measured.. Duration of support was comparable between ACE-I and control subjects (96 +/- 65 days vs. 109 +/- 22 days). Pre-LVAD Ang I and II and total and cross-linked collagen were similar between groups. Post-LVAD, Ang II was reduced in the ACE-I group but increased in control subjects (181 +/- 7 fmol/g vs. 262 +/- 41 fmol/g; p < 0.05). Similarly, cross-linked collagen decreased during LVAD support in the ACE-I group. Left ventricular (LV) mass and myocardial stiffness were lower in the ACE-I group. ACE-I normalized the LV and right ventricular (RV) MMP-1/TIMP-1 ratio. Collagen content and characteristics of the RV were not affected by ACE-I.. ACE-I therapy was associated with decreased Ang II, myocardial collagen content, and myocardial stiffness during LVAD support. This is the first demonstration of a pharmacologic therapy that can impact myocardial properties during mechanical unloading, and it could foster new lines of investigation in strategies of enhancing myocardial recovery during LVAD support.

Topics: Adult; Aged; Analysis of Variance; Angiotensin I; Angiotensin-Converting Enzyme Inhibitors; Biomarkers; Biopsy, Needle; Case-Control Studies; Collagen; Extracellular Matrix; Female; Heart Failure; Heart-Assist Devices; Humans; Immunohistochemistry; Male; Middle Aged; Myocardial Contraction; Postoperative Care; Preoperative Care; Probability; Prognosis; Reference Values; Retrospective Studies; Sensitivity and Specificity; Severity of Illness Index; Survival Rate; Tissue Inhibitor of Metalloproteinase-1; Treatment Outcome

The beneficial effects of ACE inhibitors are generally ascribed to blockade of neurohormonal activation. However, especially in chronic heart failure (CHF) patients plasma angiotensin II and aldosterone levels can be elevated despite ACE inhibition, the so-called ACE escape. In the present study, we aimed to identify the frequency and determinants of ACE escape in CHF patients.. We studied 99 stable chronic heart failure patients (NYHA class III and IV, 66% ischemic etiology) receiving long-term therapy with ACE inhibitors. In all patients, cardiac, renal, and neurohormonal parameters were measured. ACE escape was defined as plasma angiotensin level > or = 16 pmol/L.. Mean (+/- SD) left ventricular ejection fraction of our 99 patients (79 men and 20 women, age 69 +/- 12 years) was 28 +/- 10%. In addition to an ACE inhibitor, 93% of patients received diuretics, 71% a beta-blocker, and 49% spironolactone. None of the patients used an angiotensin receptor blocker. In our population, 45% of the patients had an angiotensin II plasma concentration higher than 16 pmol/L (median concentration was 14.1 pmol/L). Spironolactone use was an independent predictor of elevated plasma angiotensin II levels. Furthermore, spironolactone users had significantly higher plasma active renin protein and aldosterone levels. Plasma angiotensin II concentration was positively correlated to active renin, plasma angiotensin I and plasma aldosterone. No correlation was found between plasma angiotensin II levels and serum ACE activity, dose of ACE inhibitor, or duration of use.. In a group of severe chronic heart failure patients, 45% had elevated plasma angiotensin II levels independent of serum ACE activity despite long-term ACE inhibitor use. Although a causal link could not be proven, an association was found between spironolactone use and active renin protein, angiotensin II and aldosterone levels, suggesting that escape from ACE is mainly caused by a feedback mechanism.

Topics: Aged; Aged, 80 and over; Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Feedback, Physiological; Female; Heart Failure; Humans; Male; Middle Aged; Mineralocorticoid Receptor Antagonists; Peptidyl-Dipeptidase A; Renin; Renin-Angiotensin System; Spironolactone

Contribution of the natriuretic peptide system to the development of heart failure (HF) in vivo was examined using mice lacking or having decreased natriuretic peptide receptor-A (NPRA), a guanylyl cyclase-linked receptor.. Volume-overloaded HF was produced by aortocaval fistula in mice with wild-type (+/+), heterozygous (+/-), and homozygous null mutants (-/-) of the NPRA gene. Severity of HF was assessed 4 weeks after operation on the basis of organ weight, hemodynamics, echocardiographic indices, urinary variables, neurohumoral factors, and myocardial gene expression.. There were no significant differences in lung weight, kidney weight, left ventricular end-diastolic pressure (LVEDP), left ventricular systolic function, or urinary variables among the three sham-operated groups; however, sham-operated (-/-) mice had higher blood pressure and individual cardiac chamber weights than did (+/+) mice. In contrast, (-/-) mice with aortocaval fistula had higher LVEDP, left and right ventricular weights, lung weight, and left ventricular dimension, as well as lower fractional shortening and urinary sodium and cyclic guanosine monophosphate (cGMP) excretion than did (+/+) mice with aortocaval fistula. In addition, ventricular mRNA expression of natriuretic peptides and beta-myosin heavy chain increased markedly only in (-/-) mice. Plasma atrial natriuretic peptide, renin, and aldosterone, but not cGMP, showed greater responses to aortocaval fistula in (-/-) mice than in (+/+) mice. Both sham-operated and aortocaval fistula NPRA (+/-) mice almost consistently showed a phenotype intermediate between those of NPRA (-/-) and NPRA (+/+) mice.. These results provide genetic evidence that NPRA signaling protects against HF induced by volume overload in mice.

Topics: Aldosterone; Angiotensin I; Animals; Atrial Natriuretic Factor; Blood Volume; Cyclic GMP; Disease Susceptibility; Guanylate Cyclase; Heart Failure; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Models, Animal; Myocardium; Myosin Heavy Chains; Natriuretic Peptide, Brain; Protein Isoforms; Receptors, Atrial Natriuretic Factor; Renin; Renin-Angiotensin System; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Signal Transduction

Angiotensin-converting enzyme inhibitors have been shown to reduce morbidity and mortality in patients with heart failure. The angiotensin type-1 blocking and cardioprotective properties of perindopril and enalapril were studied in a rat model of dilated cardiomyopathy after autoimmune myocarditis. Enalapril at 20 mg/kg showed the same angiotensin type-1 blocking action as perindopril at 2 mg/kg in rats with heart failure. Twenty-eight days after immunization, surviving Lewis rats (90/120 = 75%) were divided into six groups and administered perindopril at 0.02, 0.2 and 2 mg/kg per day (Groups P0.02, P0.2 and P2), enalapril at 2 and 20 mg/kg per day (Groups E2 and E20) or vehicle alone (Group V, all groups n = 15). After oral administration for 1 month, four of 15 (27%) rats in Group V, and two (13%) in Groups P0.02 and E2 died. None of the animals in Groups P0.2, P2 and E20, or normal rats (Group N) died. Although both angiotensin-converting enzyme inhibitors improved ventricular function in a dose-dependent manner, the left ventricular end-diastolic pressure and area of myocardial fibrosis were lower, and +/- dP/dt was higher in Group P2 (4.9 +/- 0.6 mmHg, 7.5 +/- 1.4% and +2651 +/- 254/-2622 +/- 189 mmHg/s, respectively) than in Group V (16.7 +/- 1.3, 36 +/- 2.6 and +2659 +/- 176/-2516 +/- 205, respectively) and Group E20 (7.5 +/- 2.5, 15.6 +/- 2.0 and +2018 +/- 110/-2097 +/- 102, respectively). Although the expression levels of transforming growth factor-beta1 and collagen-III mRNA in Group V (36.3 +/- 5.7 and 157.6 +/- 12.7%) were significantly higher than those in Group N (19.6 +/- 3.0 and 65.2 +/- 1.5%, both p < 0.01), they were reduced in Group P2 (21.4 +/- 5.9 and 75.2 +/- 9.3%, both p < 0.01). These results suggest that although enalapril can block increases in blood pressure caused by circulating angiotensin type-1, perindopril at 2 mg/kg may confer greater protection than enalapril at 20 mg/kg against injury from the renin-angiotensin system in heart failure.

Topics: Administration, Oral; Angiotensin I; Animals; Cardiomyopathy, Dilated; Collagen Type III; Disease Models, Animal; Dose-Response Relationship, Drug; Enalapril; Endomyocardial Fibrosis; Gene Expression; Heart Failure; Hemodynamics; Hypertension; Infusions, Intravenous; Male; Pericardial Effusion; Perindopril; Rats; Rats, Inbred Lew; RNA, Messenger; Survival Rate; Time Factors; Transforming Growth Factor beta; Transforming Growth Factor beta1; Ventricular Dysfunction, Left; Ventricular Pressure

Topics: Angiotensin I; Angiotensin-Converting Enzyme Inhibitors; Animals; Heart Failure; Humans; Myocardial Infarction; Peptide Fragments; Rats; Vasodilation

Medical treatment of chronic heart failure is applied in accordance with the recommendations of the Task Force Report of the European Society of Cardiology [9] adapted to the respective NYHA stage of the cardiac failure. Currently, it includes the use of ACE inhibitors, beta blockers, AT1 receptor antagonists, diuretics including the aldosterone antagonists, and digitalis. While a positive impact on the prognosis has been confirmed for ACE inhibitors, beta blockers and aldosterone antagonists, this is not the case for diuretics and digitalis. These substance groups are used in the treatment of chronic heart failure because of their morbidity-lowering action. The objective of more recent therapeutic concepts is to block neurohumoral achses or local maladaptation processes (e.g. endothelial antagonists, cytokine inhibition, apoptosis inhibition) activated during the heart failure, or to promote protective mechanisms (e.g. endopeptidase inhibition). Here, however, the results of ongoing or planned randomized studies have to be awaited.

Topics: Adrenergic beta-Antagonists; Angiotensin I; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Antihypertensive Agents; Cardiac Glycosides; Chronic Disease; Controlled Clinical Trials as Topic; Diuretics; Drug Therapy, Combination; Heart Failure; Humans; Placebos; Prognosis; Risk Factors

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Blood Vessels; Heart Failure; Humans

Topics: Adaptation, Physiological; Angiotensin I; Animals; Endothelium, Vascular; Heart; Heart Failure; Myocardial Infarction; Peptide Fragments; Rats; Rats, Inbred Lew; Renin-Angiotensin System

The renin-angiotensin system (RAS) is a key player in the progression of heart failure. Angiotensin-(1-7) is thought to modulate the activity of the RAS. Furthermore, this peptide may play a part in the beneficial effects of angiotensin-converting enzyme inhibitors in cardiovascular disease. We assessed the effects of angiotensin-(1-7) on the progression of heart failure.. Male Sprague-Dawley rats underwent either coronary ligation or sham surgery. Two weeks after induction of myocardial infarction, intravenous infusion of angiotensin-(1-7) (24 microg/kg per hour) or saline was started by minipump. After 8 weeks of treatment, hemodynamic parameters were measured, endothelial function was assessed in isolated aortic rings, and plasma angiotensin-(1-7) levels were determined. Myocardial infarction resulted in a significant deterioration of left ventricular systolic and diastolic pressure, dP/dt, and coronary flow. Raising plasma levels 40-fold, angiotensin-(1-7) infusion attenuated this impairment to a nonsignificant level, markedly illustrated by a 40% reduction in left ventricular end-diastolic pressure. Furthermore, angiotensin-(1-7) completely preserved aortic endothelial function, whereas endothelium-dependent relaxation in aortas of saline-treated infarcted rats was significantly decreased.. Angiotensin-(1-7) preserved cardiac function, coronary perfusion, and aortic endothelial function in a rat model for heart failure.

Topics: Angiotensin I; Animals; Aorta; Coronary Circulation; Culture Techniques; Endothelium, Vascular; Heart Failure; Hemodynamics; Infusions, Intravenous; Male; Myocardial Infarction; Peptide Fragments; Rats; Rats, Sprague-Dawley; Vasodilation

We sought to demonstrate non-angiotensin converting enzyme (ACE) dependent angiotensin II (AII) generating pathways in resistance arteries from patients with chronic heart failure (CHF).. Non-ACE dependent AII generation occurs in resistance arteries from normal volunteers. Inhibition of non-ACE dependent AII generation may have therapeutic potential in CHF.. Resistance arteries were dissected from gluteal biopsies from patients with coronary heart disease (CHD) and preserved left ventricular function and from patients with CHF. Using wire myography, concentration response curves to angiotensin I (AI) and AII were constructed in the presence of 1) vehicle, 2) chymostatin [an inhibitor of chymase], 3) enalaprilat, and 4) the combination of chymostatin and enalaprilat.. In resistance arteries from patients with CHD, the vasoconstrictor response to AI was not inhibited by either inhibitor alone (chymostatin [p > or = 0.05] or enalaprilat [p > or = 0.05]) but was significantly inhibited by the combination (p < 0.001). In arteries from patients with CHF, AI responses were inhibited by enalaprilat (p < 0.05) but not by chymostatin alone (p > 0.05). The combination ofchymostatin and enalaprilat markedly inhibited the response to AI (p < 0.001) to a greater degree than enalaprilat alone (p < or = 0.01).. Non-ACE dependent AII generating pathways exist in resistance arteries from patients with both CHF and CHD. In resistance arteries from patients with CHD, inhibition of either the ACE or chymase pathway alone has no effect on AII generation, and both pathways must be blocked before the vasoconstrictor action of AI is inhibited. In CHF, blockade of ACE results in marked inhibition of responses to AI, but this is enhanced by coinhibition of chymase. These studies suggest that full suppression of the renin-angiotensin system cannot be achieved by ACE inhibition alone and provide a rationale for developing future therapeutic strategies.

Topics: Acetylcholine; Aged; Angina Pectoris; Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Arteries; Bradykinin; Chymases; Enalaprilat; Female; Heart Failure; Humans; In Vitro Techniques; Losartan; Male; Middle Aged; Oligopeptides; Peptidyl-Dipeptidase A; Serine Endopeptidases; Vascular Resistance; Vasoconstriction

To determine the effects of physiological alterations in endogenous angiotensin II activity on basal renal sympathetic nerve activity (RSNA) and its arterial baroreflex regulation, angiotensin II type 1 receptor antagonists were microinjected into the rostral ventrolateral medulla of anesthetized rats consuming a low, normal, or high sodium diet that were instrumented for simultaneous measurement of arterial pressure and RSNA. Plasma renin activity was increased in rats fed a low sodium diet and decreased in those fed a high sodium diet. Losartan (50, 100, and 200 pmol) decreased heart rate and RSNA (but not mean arterial pressure) dose-dependently; the responses were significantly greater in rats fed a low sodium diet than in those fed a high sodium diet. Candesartan (1, 2, and 10 pmol) decreased mean arterial pressure, heart rate, and RSNA dose-dependently; the responses were significantly greater in rats fed a low sodium diet than in those fed a normal or high sodium diet. [D-Ala(7)]Angiotensin-(1-7) (100, 200, and 1000 pmol) did not affect mean arterial pressure, heart rate, or RSNA in rats fed either a low or a high sodium diet. In rats fed a low sodium diet, candesartan reset the arterial baroreflex control of RSNA to a lower level of arterial pressure, and in rats with congestive heart failure, candesartan increased the arterial baroreflex gain of RSNA. Physiological alterations in the endogenous activity of the renin-angiotensin system influence the bradycardic, vasodepressor, and renal sympathoinhibitory responses to rostral ventrolateral medulla injection of antagonists to angiotensin II type 1 receptors but not to angiotensin-(1-7) receptors.

Topics: Angiotensin I; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Animals; Antihypertensive Agents; Baroreflex; Benzimidazoles; Biphenyl Compounds; Blood Pressure; Dose-Response Relationship, Drug; Heart Failure; Heart Rate; Hemodynamics; Kidney; Losartan; Male; Medulla Oblongata; Microinjections; Peptide Fragments; Rats; Rats, Sprague-Dawley; Receptors, Angiotensin; Renin; Renin-Angiotensin System; Sodium, Dietary; Sympathetic Nervous System; Tetrazoles

1. Inhibition of the renin-angiotensin system (RAS) improves symptoms and prognosis in heart failure. The experimental basis for these benefits remains unclear. We examined the effects of inhibition of ACE or blockade of angiotensin II type 1 (AT1) receptor on the haemodynamics, cardiac G-proteins, and collagen synthesis of rats with coronary artery ligation (CAL), a model in which chronic heart failure (CHF) is induced. 2. Rats were orally treated with the ACE inhibitor trandolapril (3 mg kg(-1) day(-1)) or the AT1 receptor blocker L-158809 (1 mg kg(-1) day(-1)) from the 2nd to 8th week after CAL. CAL resulted in decreases in the left ventricular systolic pressure and its positive and negative dP/dt, an increase in the left ventricular end-diastolic pressure, and the rightward shift of the left ventricular pressure-volume curve. Long-term treatment with either drug improved these signs of CHF to a similar degree. 3. Cardiac Gsalpha and Gqalpha protein levels decreased, whereas the level of Gialpha protein increased in the animals with CHF. Long-term treatment with trandolapril or L-158809 attenuated the increase in the level of cardiac Gialpha protein of the animals with CHF without affecting Gsalpha and Gqalpha protein levels. Cardiac collagen content of the failing heart increased, whose increase was blocked by treatment with either drug. 4. Exogenous angiotensin I stimulated collagen synthesis in cultured cardiac fibroblasts, whose stimulation was attenuated by either drug. 5. These results suggest that blockade of the RAS, at either the receptor level or the synthetic enzyme level, may attenuate the cardiac fibrosis that occurs after CAL and thus affect the remodelling of the failing heart.

Topics: Angiotensin I; Angiotensin II; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Animals; Body Weight; Chronic Disease; Collagen; Dose-Response Relationship, Drug; Fibroblasts; GTP-Binding Proteins; Heart; Heart Failure; Heart Septum; Heart Ventricles; Hemodynamics; Imidazoles; Indoles; Lung; Male; Organ Size; Peptidyl-Dipeptidase A; Rats; Rats, Wistar; Receptor, Angiotensin, Type 1; Receptor, Angiotensin, Type 2; Tetrazoles

The renin-angiotension-aldosterone system (RAAS) was studied in 93 patients with pulmonary tuberculosis complicated by chronic heart failure (CHF). Radioimmunoassay was used to determine plasma renin activity (PRA) and serum angiotensin I and aldesterone levels. There was higher RAAS activity, as shown by elevated PRA. RAAS activity decreased during CHF treatment with angiotension-converting enzyme inhibitors (captopril, ramipril, prestarium) and an angiotensin II-receptor blocker (cosaar), which is indicative of the efficiency of CHF treatment.

Topics: Aldosterone; Angiotensin I; Angiotensin-Converting Enzyme Inhibitors; Antihypertensive Agents; Captopril; Heart Failure; Humans; Radioimmunoassay; Ramipril; Renin; Renin-Angiotensin System; Tuberculosis, Pulmonary

Topics: Angiotensin I; Angiotensin Receptor Antagonists; Antihypertensive Agents; Biphenyl Compounds; Heart Failure; Humans; Hypertension; Irbesartan; Losartan; Meta-Analysis as Topic; Tetrazoles; Valine; Valsartan

The added benefits of angiotensin II type I receptor (AT(1)) blockers (ARBs) to ACE inhibition suggests that recommended doses of ACE inhibitors provide only partial inhibition of ACE in chronic heart failure (CHF). Accordingly, the level of ACE inhibition was assessed by the pressor response to angiotensin (Ang) I in patients who had been treated with recommended doses of ACE inhibitors.. Forty-two patients with CHF receiving 40 mg/d of a long-acting ACE inhibitor or 150 mg of captopril were studied. Radial artery systolic pressure (RASP, mm Hg) was monitored noninvasively. The pressor response to ascending doses of Ang I was evaluated in all patients before and after administration of the ARB valsartan. The pressor response to Ang I before and after valsartan was also reevaluated in 11 patients after the dose of ACE inhibitor was doubled for 1 week. RASP increased linearly with significantly ascending doses of Ang I despite treatment with ACE inhibitors. The pressor response to Ang I was blunted significantly by valsartan. Ang I-induced increase in RASP did not correlate with duration of ACE inhibitor therapy. After the dose of ACE inhibitors was doubled, the pressor response to Ang I was no longer different from that noted after valsartan.. Recommended doses of ACE inhibitors do not fully inhibit ACE in CHF. The level of ACE inhibition achieved is not related to duration of ACE inhibitor therapy. Greater ACE inhibition is also achieved at twice the recommended doses of ACE inhibitors.

Topics: Angiotensin I; Angiotensin II; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Antihypertensive Agents; Blood Pressure; Dose-Response Relationship, Drug; Drug Therapy, Combination; Enalapril; Female; Fosinopril; Heart Failure; Humans; Lisinopril; Male; Peptidyl-Dipeptidase A; Receptor, Angiotensin, Type 1; Receptor, Angiotensin, Type 2; Receptors, Angiotensin; Tetrazoles; Treatment Failure; Valine; Valsartan

Three children with renal hypertension are described. Two had histories of neuroblastoma treated by surgical resection and chemotherapy. They both presented later with unilateral atrophic kidney and marked hypertension. Only the child with severe cardiac failure demonstrated high plasma brain natriuretic peptide (BNP) concentrations. The remaining patient had a history of chronic nephritis treated with continuous ambulatory peritoneal dialysis. She also had chronic hypertension and severe cardiac failure. This child demonstrated high plasma BNP levels. The endogenous secretion of BNP is not triggered by hypertension alone, even though exogenous BNP has the pharmacological effect of reducing renin activity.

Topics: Adolescent; Angiotensin I; Angiotensin II; Atrophy; Blood Pressure; Child; Child, Preschool; Female; Heart Failure; Humans; Hypertension, Renal; Kidney; Male; Natriuretic Peptide, Brain; Neuroblastoma; Renin; Ventricular Function, Left

We tested the hypothesis that a combination of angiotensin-converting enzyme inhibitor (ACEi) and angiotensin II type 1 receptor antagonist (AT1-ant) may have an additive cardioprotective effect in mice with heart failure (HF), because these two agents could have other mechanisms of action besides interrupting the renin-angiotensin system. ACEi prevent degradation of bradykinin. During treatment with AT1-ant, increased angiotensin II could activate AT2 receptors, with an antitrophic effect. To test this hypothesis, we used a mouse model of HF induced by myocardial infarction. Seven days after surgery, mice were divided into six groups and treated for 23 weeks: (a) sham ligation; (b) HF-vehicle; (c) HF-ACEi; (d) HF-AT1-ant; (e) HF-ACEi + AT1-ant (half dose of each); and (f) HF-ACEi + AT1-ant (full dose of each). Cardiac function was evaluated in conscious mice during the treatment period. The HF-vehicle group showed significantly decreased left ventricular (LV) ejection fraction (EF), shortening fraction (SF), and cardiac output (CO) and increased LV dimensions, interstitial collagen, and myocyte cross-sectional area (MCSA) compared with controls. Treatment with ACEi or AT1-ant significantly increased EF, SF, and CO and decreased LV dimensions and MCSA in mice with HF. However, a combination of these drugs did not improve cardiac function more than ACEi or AT1-ant alone. We concluded that ACEi and AT1-ant have similar cardioprotective effects and may reach maximal effect when given individually; thus no further improvement can be achieved with combined therapy in mice with HF.

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Animals; Antihypertensive Agents; Cardiac Output; Chronic Disease; Echocardiography; Female; Heart; Heart Failure; Imidazoles; Male; Mice; Mice, Inbred C57BL; Myocardial Infarction; Myocardium; Organ Size; Ramipril; Stroke Volume; Tetrazoles; Ventricular Remodeling

Angiotensin-converting enzyme (ACE) inhibitors have proven an effective means to control hypertension and manage cardiac hypertrophy. It is presently unknown if newer specific angiotensin II subtype 1 receptor (AT1R) antagonists are as effective or more effective in treating these conditions compared with ACE inhibitors. There is evidence that these classes of drugs may affect cardiac hypertrophy by different mechanisms. This study compared the effect of irbesartan, an AT1R antagonist, with that of captopril, an ACE inhibitor, on expression of early genetic markers of cardiac hypertrophy in lean male SHHF/Mcc-fa(cp) rats. SHHF/Mcc-fa(cp) rats (n = 10/group) were given captopril (100 mg/kg/day), irbesartan (50 mg/kg/day), or placebo for 16 weeks. Irbesartan and captopril significantly reduced systolic pressure and produced similar rightward shifts in the angiotensin I dose-response curve. Renal renin gene expression was increased 8.6-fold by irbesartan and 17.7-fold by captopril. The only effect on echocardiographic findings was a similar decrease in aortic peak velocity, an index of systolic function, by both treatments. Early markers of cardiac hypertrophy were significantly attenuated by both drugs. Both drugs produced marked and equivalent reductions in left ventricular atrial natriuretic peptide (ANP) messenger RNA (mRNA) levels compared with controls. This decrease in ANP gene expression was accompanied by a decrease in plasma ANP concentration in the treatment groups. The shift from V1 to V3 myosin isozymes was similarly decreased in both treatment groups, compared with controls. These data suggest that captopril and irbesartan are similarly effective in controlling expression of genes associated with ventricular hypertrophy in heart failure-prone SHHF/Mcc-fa(cp) rat.

Topics: Angiotensin I; Angiotensin II; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Animals; Antihypertensive Agents; Atrial Natriuretic Factor; Biphenyl Compounds; Blood Pressure; Body Weight; Captopril; Cardiomegaly; Dose-Response Relationship, Drug; Echocardiography; Gene Expression; Heart Failure; Irbesartan; Isoenzymes; Male; Myosin Heavy Chains; Organ Size; Rats; Rats, Inbred Strains; Receptor, Angiotensin, Type 1; Receptor, Angiotensin, Type 2; Renin; RNA, Messenger; Systole; Tetrazoles

To determine the short-term effects of angiotensin-converting enzyme (ACE) inhibition on hemodynamics and circulating levels of norepinephrine, angiotensin, and bradykinin, responses to enalaprilat and perindoprilat were examined at doses of 0.03, 0.3, and 1 mg/kg in permanently instrumented conscious dogs with pacing-induced heart failure (right ventricular pacing, 240-250 beats/min, 3 weeks). All doses of the two inhibitors produced similar decrease in mean aortic pressure and increase in cardiac output. Neither inhibitor affected plasma norepinephrine level. Both compounds induced a similar 60-80% decrease in blood angiotensin II level, a similar two- to eightfold increase in blood angiotensin I level, and a 80-95% decrease in the angiotensin II/angiotensin I ratio. There were also a fourfold to 10-fold increase in blood bradykinin-(1-9) level, a twofold increase in blood bradykinin-(1-7) level, and a 70-85% decrease in bradykinin-(1-7)/bradykinin-(1-9) ratio. In addition, the changes in total peripheral resistance induced by the two ACE inhibitors were weakly but significantly correlated with the changes in blood angiotensin II or blood bradykinin-(1-9). Thus whatever the specificity of enalaprilat and perindoprilat, both inhibitors produced similar acute hemodynamic effects in dogs with heart failure, which was associated with marked decrease in circulating angiotensin II level and increase in bradykinin-(1-9) level. This study, which measures for the first time in heart failure the blood bradykinin level after ACE inhibitors, indicates, in concert with angiotensin II reduction, a role for increased bradykinin-(1-9) level in mediating short-term hemodynamic effects of ACE inhibition in this model of heart failure.

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Animals; Blood Pressure; Bradykinin; Cardiac Output; Cardiac Pacing, Artificial; Disease Models, Animal; Dogs; Enalaprilat; Heart Failure; Indoles; Norepinephrine; Peptide Fragments; Ventricular Function, Left

Synergistic interaction between angiotensin II (Ang II) and evolving cardiodepression may play an important role in worsening chamber function, particularly in diastole. To test this hypothesis, Ang II was infused at 10 or 17 ng.kg(-1).min(-1) in 18 conscious dogs 4 days before and during induction of subacute cardiodepression by 48-hour tachypacing. The lower dose yielded negligible systemic pressure changes. Twelve additional animals served as paced-only controls. Pressure-dimension relations were recorded, and serial endocardial biopsies were obtained to assess histological and metalloproteinase (MMP) changes. Forty-eight-hour pacing alone depressed systolic function but had little effect on diastolic stiffness. Ang II alone only modestly raised diastolic stiffness at both doses and enhanced contractility at the higher dose. These changes recovered toward baseline after a 7-day infusion. However, Ang II (at either dose) combined with 48-hour pacing markedly increased ventricular stiffness (110+/-26% over baseline) and end-diastolic pressure (22+/-1.7 mm Hg). In contrast, pacing-induced inotropic and relaxation abnormalities were not exacerbated by Ang II. Zymography revealed MMP activation (72- and 92-kD gelatinases and 52-kDa caseinase) after a 4-day Ang II infusion (at both doses), which persisted during pacing. Tachypacing initiated 24 hours after cessation of a 7-day Ang II infusion also resulted in diastolic stiffening and corresponded with MMP reactivation. Ang II also induced myocyte necrosis, inflammation, and subsequent interstitial fibrosis, but these changes correlated less with chamber mechanics. Thus, Ang II amplifies and accelerates diastolic dysfunction when combined with evolving cardiodepression. This phenomenon may also underlie Ang II influences in late-stage cardiomyopathy, when chamber distensibility declines.

Topics: Angiotensin I; Angiotensin II; Animals; Diastole; Dogs; Enzyme Activation; Female; Heart Failure; Heart Rate; Hemodynamics; Male; Metalloendopeptidases; Myocardial Contraction; Tachycardia; Time Factors

AT1 receptor activation has been demonstrated to cause increased vascular resistance properties which may be of particular importance in the setting of congestive heart failure (CHF). The overall goal of this study was to examine the effects of ACE inhibition (ACEI) alone, AT1 receptor blockade alone and combined ACEI and AT1 receptor blockade on LV pump function, systemic hemodynamics and regional blood flow patterns in the normal state and with the development of pacing induced CHF, both at rest and with treadmill induced exercise.. Pigs (25 kg) were instrumented in order to measure cardiac output (CO), systemic (SVR) and pulmonary vascular (PVR) resistance, neurohormonal system activity, and myocardial blood flow distribution in the conscious state and assigned to one of 4 groups: (1) rapid atrial pacing (240 bpm) for 3 weeks (n = 7); (2) ACEI (benazeprilat, 3.75 mg/day) and pacing (n = 7); (3) AT1 receptor blockade (valsartan, 60 mg/day) and rapid pacing (n = 7); and (4) ACEI and AT1 receptor blockade (benazeprilat/valsartan, 1/60 mg/day, respectively) and pacing (n = 7). Measurements were obtained at rest and with treadmill exercise (15 degrees, 3 miles/h; 10 min) in the normal control state and after the completion of the treatment protocols. With rapid pacing, CO was reduced at rest and with exercise compared to controls. ACEI or AT1 blockade normalized CO at rest, but remained lower than control values with exercise. Combination therapy normalized CO both at rest and with exercise. Resting SVR in the CHF group was higher than controls and SVR fell to a similar degree with exercise; all treatment groups reduced resting SVR. With exercise, SVR was reduced from rapid pacing values in the ACEI and combination therapy groups. PVR increased by over 4-fold in the rapid pacing group both at rest and with exercise, and was reduced in all treatment groups. In the combination therapy group, PVR was similar to control values with exercise. Plasma catecholamines and endothelin levels were increased by over 3-fold with chronic rapid pacing, and were reduced in all treatment groups. In the combination therapy group, the relative increase in catecholamines and endothelin with exercise were significantly blunted when compared to rapid pacing only values. LV myocardial blood flow at rest was reduced in the rapid pacing only and monotherapy groups, but was normalized with combination therapy.. These findings suggest that with developing CHF, combined ACE inhibition and AT1 receptor blockade improved vascular resistive properties and regional blood flow distribution to a greater degree than that of either treatment alone. Thus, combined ACEI and AT1 receptor blockade may provide unique benefits in the setting of CHF.

Topics: Angiotensin I; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Animals; Benzazepines; Cardiac Pacing, Artificial; Endothelins; Epinephrine; Heart Failure; Hemodynamics; Male; Norepinephrine; Physical Exertion; Regional Blood Flow; Renin; Swine; Tetrazoles; Valine; Valsartan; Ventricular Function, Left

Topics: Angiotensin I; Angiotensin II; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Antihypertensive Agents; Bradykinin; Captopril; Clinical Trials as Topic; Heart Failure; Humans; Losartan; Receptors, Angiotensin

Topics: Angiotensin I; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Drug Therapy, Combination; Heart Failure; Humans; Hypertension; Kidney

The efficacy of ACE inhibitors in congestive heart failure (CHF) might be affected by the pathophysiological status present at the onset of treatment. We compared in a rat model the effects of ACE inhibition (lisinopril, 10 mg.kg-1.d-1) initiated early (1 week) or late (3 months) after myocardial infarction (i.e., at time points corresponding to moderate or severe CHF without or with established cardiac remodeling).. Survival was improved by early treatment at 3 months (from 76% to 95%) and by both early and delayed treatment at 9 months (placebo, 28%; early, 90%; delayed, 61%). Delayed treatment was initiated in a more severe pathophysiological context of CHF than early treatment, illustrated in untreated rats by higher left ventricular (LV) end-diastolic and central venous pressures and by increased LV weight and LV cavity circumference. After 9 months, early and delayed treatments reduced systolic, LV end-diastolic, and central venous pressures. Both treatments also similarly decreased LV weight, LV cavity circumference, and LV collagen density.. In this rat model of CHF, early and delayed ACE inhibitor treatments both increase survival and exert similar beneficial effects on cardiac hemodynamics and remodeling. Although early treatment prevents the development of ventricular dysfunction and remodeling, delayed treatment is capable of reversing cardiac hypertrophy and remodeling, as well as ventricular dysfunction. Thus, ACE inhibitors exert marked beneficial effects even when treatment is initiated late into the evolution of heart failure (ie, at a time of established ventricular dysfunction and remodeling).

Topics: Analysis of Variance; Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Animals; Blood Pressure; Diastole; Femoral Artery; Heart; Heart Failure; Hemodynamics; In Vitro Techniques; Lisinopril; Male; Muscle, Smooth, Vascular; Myocardial Infarction; Myocardium; Rats; Rats, Wistar; Survival Rate; Vascular Resistance; Ventricular Function, Left

Topics: Adrenergic beta-Antagonists; Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Anti-Arrhythmia Agents; Biphenyl Compounds; Heart Failure; Humans; Imidazoles; Losartan; Prognosis; Tetrazoles

The aortovenocaval fistular (AVF) rat represents a model of heart failure caused by increased cardiac volume overload and reduced renal function. Both circulating vasoconstrictors like the renin-angiotensin-aldosterone system and vasodilators like atrial and brain natriuretic peptides (ANP and BNP) are activated in this animal model of heart failure. In addition, neutral endopeptidase 24.11 (NEP) in plasma and urine is elevated in AVF rats. In the present investigation we examined the renal and hormonal effects of the NEP inhibitor, ecadotril, in acute and chronic studies in rats with an aortovenocaval fistula (AVF).. Sprague Dawley rats (350-430 g) were prepared by introducing a shunt between abdominal aorta and the vena cava.. Acute administration of the neutral endopeptidase inhibitor, ecadotril (30 mg/kg p.o.), significantly improved the reduced renal excretion of sodium in AVF rats (83 +/- 10 to 145 +/- 14 mumol/kg/h, P < 0.01) but had no significant effect in sham-operated rats. However, neutral endopeptidase activity in urine was significantly decreased after ecadotril in both groups. Plasma ANP was increased after ecadotril only in AVF rats (275 +/- 83 to 748 +/- 187 pg/ml, P < 0.05), whereas the increase in plasma BNP was not statistically significant. After 4 weeks of observation the ANP and BNP plasma levels, renin activity (PRA), angiotensin I, and neutral endopeptidase activity were significantly higher in AVF rats than in sham-operated rats. Four weeks on ecadotril (30 mg/kg p.o., b.i.d.) increased plasma ANP (245 +/- 48 as opposed to 450 +/- 77 pg/ml, P < 0.05) and decreased PRA (11.3 +/- 1.5 as opposed to 6.8 +/- 1.2 ng/ml/h, P < 0.005) in AVF rats. Plasma NEP activity was inhibited in both groups. Ventricle weight was significantly higher in AVF rats than in sham-operated controls, and ecadotril treatment over 4 weeks decreased ventricular hypertrophy to a slight extent.. These results indicate that in the AVF rat model of heart failure the neutral endopeptidase inhibitor, ecadotril, improves the reduced kidney function in AVF rats by raising natriuretic peptides in plasma and probably in urine. NEP inhibition with ecadotril could therefore offer useful therapeutic possibilities in the treatment of heart failure.

Topics: Angiotensin I; Animals; Aorta; Arteriovenous Fistula; Atrial Natriuretic Factor; Disease Models, Animal; Heart Failure; Natriuretic Peptide, Brain; Neprilysin; Nerve Tissue Proteins; Protease Inhibitors; Rats; Rats, Sprague-Dawley; Renin; Sodium; Thiorphan; Venae Cavae

Recent studies are reviewed dealing with the putative roles of the cardiac renin-angiotensin system in the development of pressure-overload hypertrophy and the subsequent transition from adaptive hypertrophy to diastolic dysfunction, impaired systolic function and cardiac failure. The results of these studies, which employed the aortic banded rat model of cardiac hypertrophy, indicate that the intracardiac conversion of angiotensin I (Ang I) to angiotensin II (Ang II) is significantly increase in hypertrophied hearts compared with hearts from age-matched, sham-operated controls, and that Ang II may have a direct effect of slowing relaxation and altering diastolic tone in the hypertrophied heart. Furthermore, in patients with aortic stenosis and severe baseline abnormalities of diastolic relaxation and filling, acute intracardiac angiotensin-converting enzyme (ACE) inhibition, totally in the absence of any systemic effect on neurohormones, improved diastolic function. ACE inhibition was found to reduce net ACE activity and to increase plasma renin activity in aortic banded animals compared with untreated banded controls. There was also a trend for circulating noradrenaline levels to be increased at this stage of transition to failure in the untreated banded animals but ACE inhibition tended to restore the levels back to normal. In ACE inhibitor-treated animals, left ventricular (LV) diastolic pressure was significantly reduced, despite the persistent elevation of systolic pressure, but not yet restored completely to normal. In untreated, banded animals the transition to cardiac failure was evidenced as an increase in both systolic and diastolic dimensions with a reduction in fractional shortening.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Animals; Aortic Valve Stenosis; Blood Pressure; Cardiomegaly; Disease Models, Animal; Heart Failure; Humans; Myocardial Contraction; Rats; Renin-Angiotensin System; Ventricular Function, Left

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Clinical Trials as Topic; Drug Administration Schedule; Heart Failure; Humans

The aim of the study was to compare, in a rat model of congestive heart failure, the effect of captopril, a selective angiotensin-converting enzyme (ACE; EC 3.4.15.1) inhibitor, to that of alatriopril, a mixed inhibitor of ACE and atriopeptidase (EC 3.4.24.11), an enzyme implicated in the degradation of atrial natriuretic factor (ANF). Myocardial infarction was induced by ligation of the left coronary artery. Groups of rats received orally twice daily captopril (10 mg/kg), alatriopril (100 mg/kg) or vehicle. Treatments were started 18 to 20 h after ligation and continued for 4 weeks. Hypertrophic and hormonal changes reflecting congestive heart failure were assessed in rats with large infarcts by measuring the relative weight of cardiac tissues as well as by assaying ANF in heart and plasma and by measuring renin activity in plasma. Both treatments significantly reduced cardiac hypertrophy, but alatriopril showed a greater efficacy than captopril--the increase in relative heart weight reaching 38% with captopril and only 22% with alatriopril (P < .05). The hypertrophy of right ventricle was reduced by 47% with alatriopril and by 35% with captopril (N.S.), whereas the corresponding reductions for atria were 47% vs. 21% (P < .05). Both treatments prevented the ligation-induced increase of ANF level in the right ventricle. In contrast, plasma ANF level was significantly reduced after captopril but not after alatriopril treatment, a difference that probably reflects the protection of endogenous ANF in circulation resulting from atriopeptidase inhibition. Plasma renin was increased by 36-fold after captopril but only by 1.6-fold after alatriopril, a difference that presumably reflects the inhibition of renal renin secretion by endogenous ANF after alatriopril. These data suggest that enhancement of ANF levels in circulation via atriopeptidase inhibition magnifies the capacity of ACE inhibitors to prevent cardiac hypertrophy, and they show the potential therapeutic value of mixed ACE-atriopeptidase inhibitors in congestive heart failure.

Topics: Alanine; Amino Acid Sequence; Angiotensin I; Angiotensin-Converting Enzyme Inhibitors; Animals; Atrial Natriuretic Factor; Blood Pressure; Body Weight; Bradykinin; Captopril; Cardiomegaly; Dioxoles; Disease Models, Animal; Heart Failure; Hormones; Male; Molecular Sequence Data; Myocardial Infarction; Myocardium; Neprilysin; Peptidyl-Dipeptidase A; Rats; Rats, Wistar; Renin

In vitro coronary artery responsiveness to angiotensin I, angiotensin II, noradrenaline, phenylephrine, BHT 920, and potassium chloride together with functional relaxation to acetylcholine was investigated in dogs with pacing-induced heart failure treated with enalapril (oral administration of 10 mg.day-1) for a mean duration of 26 days. Although maximal responses generated to both angiotensin I and angiotensin II were unaltered in the enalapril-treated group, angiotensin II became more potent following enalapril treatment: the EC50 for angiotensin II following placebo treatment was 2.4 (0.6-5.8; 95% confidence limits) nM and following enalapril treatment was 0.03 (0.007-0.1; 95% confidence limits) nM. In addition to the above changes, coronary artery rings from dogs treated with enalapril developed significantly less tension to noradrenaline, phenylephrine, and BHT 920. In contrast, responses to potassium chloride were unaltered following enalapril treatment. However, the relaxation to acetylcholine was enhanced from 38.9 +/- 3.0 to 50.4 +/- 3.5% (placebo versus enalapril, p < 0.05). These findings indicate that enalapril may possess alpha-blocking properties and enhance the relaxation response to acetylcholine through an endothelial-dependent mechanism in addition to inhibiting converting enzyme.

Topics: Acetylcholine; Adrenergic alpha-Agonists; Angiotensin I; Angiotensin II; Animals; Cardiac Pacing, Artificial; Coronary Vessels; Disease Models, Animal; Dogs; Enalapril; Endothelium, Vascular; Heart Failure; In Vitro Techniques; Male; Vasoconstriction

1) Captopril was orally administered in a dose of 12.5 mg to 12 patients with congestive heart failure to follow changes in its blood concentration and determine changes in clinical test values. 2) The blood concentration of captopril reached its peak in 2 h after medication, the mean value being 274 ng/ml and the half-life 3.16 h. The Tmax and T1/2 were found to be extended as compared with those of normal humans and hypertensive patients that had been reported. No significant differences were noted between Group I of mild cases and Group II of serious cases. 3) Following administration of captopril, a rise in angiotensin I and renin activity and a reduction in aldosterone were noted. These were found to be correlated or inversely correlated with the changes in the blood concentration of captopril. Greater changes were noted in Group II than in Group I. All clinical test values in each group tended to return to the control value 6h after the administration.

Topics: Aldosterone; Angiotensin I; Angiotensin II; Captopril; Epinephrine; Female; Half-Life; Heart Failure; Humans; Male; Metabolic Clearance Rate; Middle Aged; Norepinephrine; Renin

1. The effects of heart failure due to chronic myocardial infarction on the responsiveness to injected angiotensin I and ACE inhibition by intravenous cilazapril (1 mg kg-1) were evaluated. 2. For this purpose one group of 17 rats with a 4-week old myocardial infarction was compared with a group of 10 sham operated rats. 3. Heart failure increased markedly the responsiveness of the renal and mesenteric vascular beds to ACE inhibition which produced a vasodilation in these two vascular beds. 4. This increased responsiveness was most likely due to a stimulation of the renin-angiotensin system without any change of sensitivity to angiotensin I of the renal and mesenteric vascular beds. 5. Cilazapril produced the same level of ACE inhibition in both groups of rats.

Topics: Angiotensin I; Angiotensin-Converting Enzyme Inhibitors; Animals; Chronic Disease; Cilazapril; Heart Failure; Hemodynamics; Myocardial Infarction; Myocardium; Pyridazines; Rats; Rats, Inbred Strains; Vascular Resistance

In 14 patients with congestive heart failure (CHF) of various grade (NYHA class 2-4) the effects of zofenopril calcium (SQ 26,991) on blood pressure and forearm circulation were studied by venous occlusion plethysmography. Changes in plasma renin activity (PRA), aldosterone, Atrial natriuretic factor (ANF) and arginine-vasopressin (AVP) were also measured. Two hours after oral administration of 7.5 mg of zofenopril we observed a decrease in blood pressure, heart rate, and forearm vascular resistance along with an increase in venous distensibility. Zofenopril also decreased ANP levels in a manner directly related to peripheral venodilatation (r = .64; P less than .05) and modified arginine-vasopressin (AVP) proportionally to the fall in blood pressure observed in response to drug administration (%SBP/%AVP: r = .64, P less than .05; %DBP/%AVP: r = .67, P less than .05). Hemodynamic and humoral responses to zofenopril occurred without any significant unwanted adverse reaction, even in patients with greater pressor reduction. We conclude that oral acute zofenopril administration, in patients with congestive heart failure, causes an arterial and venous forearm vasodilatation which is probably involved in the acute changes in plasma levels of ANF and AVP observed after drug administration.

Topics: Administration, Oral; Aged; Angiotensin I; Arginine Vasopressin; Atrial Natriuretic Factor; Blood Pressure; Captopril; Female; Forearm; Heart Failure; Heart Rate; Humans; Male; Middle Aged; Renin; Vasodilation; Veins

Topics: Angiotensin I; Captopril; Heart Failure; Hemodynamics; Humans; Myocardial Contraction; Renin-Angiotensin System; Sodium

1. The effects of the angiotensin-converting enzyme (ACE) inhibitor lisinopril on plasma vasoactive intestinal polypeptides (VIP) and plasma noradrenaline, adrenaline and dopamine were studied in 12 patients with congestive heart failure over two consecutive 48-hr periods. The first day in each period served as a treatment day and the second as a control day. 2. A parallel monitoring was made of various hormonal parameters related to the renin-angiotensin-aldosterone system, and a right-heart catheter was used to monitor haemodynamics at rest. 3. Potent inhibition of the renin-system (as demonstrated by decreases in angiotensin converting enzyme (ACE) activity, angiotensin II and plasma aldosterone) together with improved haemodynamics (decreases in mean right atrial pressure, mean pulmonary arterial pressure, mean pulmonary capillary wedge pressure and mean systemic arterial pressure) were recorded. 4. Plasma VIP was significantly increased by a mean of 20.3% (P less than 0.01) on the lisinopril treatment days compared with the control days, whereas circulating catecholamines showed no significant pattern of change. 5. It is postulated that the potent vasodilatory neuromodulator VIP is implicated in the ACE inhibitor effects. 6. The ACE is a non-specific peptidase that previously has been implicated in the potentiation of other vasoactive endogenous systems (kinins and enkephalins).

Topics: Adult; Aged; Aldosterone; Angiotensin I; Angiotensin-Converting Enzyme Inhibitors; Catecholamines; Enalapril; Female; Heart Failure; Hemodynamics; Humans; Lisinopril; Male; Middle Aged; Renin; Vasoactive Intestinal Peptide

The acute hemodynamic and hormonal effects of the oral angiotensin-converting enzyme (ACE) inhibitor lisinopril (MK-521) were assessed over a period of 96 hours in 12 patients with heart failure. This compound is the lysine analogue of enalaprilat (MK-422), is biologically active following absorption, and is cleared via the urine without any known metabolic transformation. Single doses of lisinopril, ranging from 1.25 mg to 10 mg, were administered on days 1 and 3, each followed by 48 hours of intensive hemodynamic observation. Across all doses, maximal reductions in mean arterial pressure (17.2%), mean pulmonary capillary wedge pressure (28%), and systemic vascular resistance (25.6%) were observed compared to baseline values. No significant changes in heart rate were recorded. Arterial blood was sampled at frequent intervals for angiotensin II, ACE activity, plasma renin activity, renin substrate, plasma aldosterone, and serum drug levels. Right atrial blood was sampled simultaneously for angiotensin I, thus permitting assessment of the degree of pulmonary conversion to angiotensin II. The results indicate potent inhibition of the renin-angiotensin-aldosterone system along with hemodynamic efficacy over a period exceeding 24 hours. Frequent clinical follow-up on long-term chronic therapy has revealed no adverse experience.

Topics: Adult; Aged; Aldosterone; Angiotensin I; Angiotensin-Converting Enzyme Inhibitors; Dose-Response Relationship, Drug; Enalapril; Female; Heart Failure; Heart Rate; Hemodynamics; Humans; Lisinopril; Male; Middle Aged; Peptidyl-Dipeptidase A; Pulmonary Wedge Pressure; Renin; Vascular Resistance

In nine patients with severe, treatment-resistant heart failure (stages IV in the NYHA classification) the acute and long-term effect of captopril were studied. In the acute experiment, peripheral resistance fell by 27% after administration of 25 mg captopril, cardiac index rose by 25%, arterial pressure, pulmonary arterial pressure and mean right atrial pressure fell by a similar amount. This haemodynamic improvement increased slightly in the course of longterm treatment (cardiac index +30%, peripheral resistance -30%, mean pulmonary arterial pressure -42%). The fall in heart rate by 15% and 25%, respectively, was an expression of haemodynamic improvement and reduction in angiotensin II. The fall in peripheral vascular resistance coincided with a 50% reduction in angiotensin II concentration. Over the longer term, 2-42 weeks, the renin system stimulation regressed with the improvement in haemodynamics. Four of the nine patients in stage IV improved to stage II, while the remaining five patients improved from IV to III.

Topics: Adult; Aged; Angiotensin I; Angiotensin II; Captopril; Chronic Disease; Drug Evaluation; Female; Heart Failure; Hemodynamics; Humans; Male; Middle Aged; Peptidyl-Dipeptidase A; Proline; Time Factors

The acute hemodynamic and hormonal effects of the oral angiotensin converting enzyme (ACE) inhibitor MK-521 were assessed over a period of 96 hours in 6 patients with heart failure. This compound is the lysine analogue of enalapril diacid (MK-422) and is biologically active following absorption. Dosages ranging from 1.25 mg to 5.0 mg were administered on days 1 and 3, followed by 48 hours intensive hemodynamic observation. Marked reduction in mean arterial pressure (25.2%), pulmonary capillary wedge pressure (47.3%), and systemic vascular resistance (34.5%) was observed. Arterial blood was sampled at frequent intervals for angiotensin I (AI), angiotensin II (AII), plasma renin activity, renin substrate, plasma aldosterone, urinary aldosterone, ACE activity, and serum drug levels. Right atrial blood was sampled simultaneously for AI and AII thus permitting reliable assessment of the degree of pulmonary conversion to angiotensin II. Prolonged inhibition of the renin-angiotensin-aldosterone system was confirmed and corresponded to drug concentration. The results indicate hemodynamic efficacy and potent ACE inhibition over a period exceeding 24 hours.

Topics: Adult; Aged; Aldosterone; Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Dipeptides; Female; Heart Failure; Hemodynamics; Hormones; Humans; Lisinopril; Male; Middle Aged; Renin; Time Factors

Topics: Adolescent; Adult; Aged; Angiotensin I; Angiotensin-Converting Enzyme Inhibitors; Captopril; Child; Heart Failure; Hemodynamics; Humans; Hypertension; Kidney; Male; Middle Aged; Proline; Renal Dialysis