The discovery, isolation and identification of aldosterone: reflections on emerging regulation and function

RAAS in diabetic retinopathy: mechanisms and therapies

Diabetic retinopathy (DR) is a complication of diabetes with a complex pathophysiology and multiple factors involved. Recently, it has been found that the upregulation of the renin-angiotensin-aldosterone system (RAAS) leads to overexpression of angiotensin II (Ang II), which induces oxidative stress, inflammation, and angiogenesis in the retina. Therefore, RAAS may be a promising therapeutic target in DR. Notably, RAAS inhibitors are often used in the treatment of hypertension. Still, the potential role and mechanism of DR must be further studied. In this review, we discuss and summarize the pathology and potential therapeutic goals of RAAS in DR.

An Abbreviated History of Aldosterone Metabolism, Current and Future Challenges

The initial isolation of adrenal steroids from large quantities of animal adrenals resulted in an amorphous fraction resistant to crystallization and identification and had potent effects on electrolyte transport. Aldosterone was eventually isolated and identified in the fraction and was soon shown to cause hypertension when in excess. The autonomous and excessive production of aldosterone, primary aldosteronism, is the most common cause of secondary hypertension. Aldosterone is metabolized in the liver and kidney, and its metabolites are conjugated with glucuronic acid for excretion. The most common liver metabolite is 3α,5β-tetrahydroaldosterone-3-glucuronide, while that of the kidney is aldosterone-18-oxo-glucuronide. In terms of their value, especially the aldosterone-18-oxo-glucuronide, is commonly used for the diagnosis of primary aldosteronism because they provide an integrated value of the total daily production of aldosterone. Conversion of aldosterone to 18-oxo-glucuronide is impeded by drugs, like some common non-steroidal anti-inflammatory drugs that compete for UDP-glucuronosyltransferase-2B7, the most important glucuronosyltransferase for aldosterone metabolism. Tetrahydroaldosterone is the most abundant metabolite and the most reliable for the diagnosis of primary aldosteronism, but it is not commonly measured.

Aldosterone Synthase Inhibitors and Dietary Interventions: A Combined Novel Approach for Prevention and Treatment of Cardiovascular Disease

Systemic hypertension (HTN) is the hallmark of cardiovascular disease and the forerunner of heart failure. These associations have been established over decades of research on essential HTN. Advancements in the treatment of patients diagnosed with HTN, consisting of alpha- or beta-adrenergic receptor blockers, calcium channel blockers, angiotensin-converting enzyme inhibitors, thiazide, or aldosterone receptor blockers known as anti-mineralocorticoids, in the presence or absence of low sodium salt diets, often fail to control blood pressure adequately to prevent morbidity and mortality. Low sodium diets have had limited success in controlling HTN because low sodium intake is associated with renin-angiotensin-aldosterone system upregulation. Therefore, upregulating aldosterone secretion, sodium, and water retention which, in turn, moves the blood pressure back toward the range of HTN dictated by the baroreceptor reset value, as a compensatory mechanism, especially in resistant HTN. These impediments to blood pressure control in HTN may have been effectively circumvented by the advent of a new class of drugs known as aldosterone synthase inhibitors, represented by baxdrostat. The mechanism of action of baxdrostat as an aldosterone synthase inhibitor demonstrates the inextricable linkage between sodium and blood pressure regulation. Theoretically, combining a low sodium diet with the activity of this aldosterone synthesis inhibitor should alleviate the adverse effect of renin-angiotensin-aldosterone system upregulation. Aldosterone synthesis inhibition should also decrease the oxidative stress and endothelial dysfunction associated with HTN, causing more endothelial nitric oxide synthesis, release, and vasorelaxation. To the best of our knowledge, this is the first systematic review to summarize evidence-based articles relevant to the use of a novel drug (aldosterone synthase inhibitor) in the treatment of HTN and cardiovascular disease. Making the current database of relevant information on baxdrostat and other aldosterone synthase inhibitors readily available will, no doubt, aid physicians and other medical practitioners in their decision-making about employing aldosterone synthase inhibitors in the treatment of patients.

History of Adrenal Research: From Ancient Anatomy to Contemporary Molecular Biology

The adrenal is a small, anatomically unimposing structure that escaped scientific notice until 1564 and whose existence was doubted by many until the 18th century. Adrenal functions were inferred from the adrenal insufficiency syndrome described by Addison and from the obesity and virilization that accompanied many adrenal malignancies, but early physiologists sometimes confused the roles of the cortex and medulla. Medullary epinephrine was the first hormone to be isolated (in 1901), and numerous cortical steroids were isolated between 1930 and 1949. The treatment of arthritis, Addison's disease, and congenital adrenal hyperplasia (CAH) with cortisone in the 1950s revolutionized clinical endocrinology and steroid research. Cases of CAH had been reported in the 19th century, but a defect in 21-hydroxylation in CAH was not identified until 1957. Other forms of CAH, including deficiencies of 3β-hydroxysteroid dehydrogenase, 11β-hydroxylase, and 17α-hydroxylase were defined hormonally in the 1960s. Cytochrome P450 enzymes were described in 1962-1964, and steroid 21-hydroxylation was the first biosynthetic activity associated with a P450. Understanding of the genetic and biochemical bases of these disorders advanced rapidly from 1984 to 2004. The cloning of genes for steroidogenic enzymes and related factors revealed many mutations causing known diseases and facilitated the discovery of new disorders. Genetics and cell biology have replaced steroid chemistry as the key disciplines for understanding and teaching steroidogenesis and its disorders.

Aldosterone as a Possible Contributor to Eye Diseases

Aldosterone, an effector molecule of the renin-angiotensin-aldosterone system (RAAS), has been receiving more attention in the field of ophthalmology because of its possible role in the pathogenesis of various eye diseases or abnormalities; it may even become a target for their treatment. Primary aldosteronism, a typical model of a systemic aldosterone excess, may cause vision loss due to various ocular diseases, such as retinal vein occlusion, central serous chorioretinopathy, and, possibly glaucoma. RAAS components are present in various parts and types of cells present in the eye. Investigations of the local RAAS in various animal models of diabetic macular edema, retinal vein occlusion, retinopathy of prematurity, central serous chorioretinopathy, and glaucoma have found evidence that aldosterone or mineralocorticoid receptors may exacerbate the pathology of these disorders. Further studies are needed to elucidate whether the modulation of aldosterone or mineralocorticoid receptors is an effective treatment for preventing vision loss in patients with eye diseases.

The Biology of Normal Zona Glomerulosa and Aldosterone-Producing Adenoma: Pathological Implications

The identification of several germline and somatic ion channel mutations in aldosterone-producing adenomas (APAs) and detection of cell clusters that can be responsible for excess aldosterone production, as well as the isolation of autoantibodies activating the angiotensin II type 1 receptor, have rapidly advanced the understanding of the biology of primary aldosteronism (PA), particularly that of APA. Hence, the main purpose of this review is to discuss how discoveries of the last decade could affect histopathology analysis and clinical practice. The structural remodeling through development and aging of the human adrenal cortex, particularly of the zona glomerulosa, and the complex regulation of aldosterone, with emphasis on the concepts of zonation and channelopathies, will be addressed. Finally, the diagnostic workup for PA and its subtyping to optimize treatment are reviewed.

Raman micro-spectroscopy as a viable tool to monitor and estimate the ionic transport in epithelial cells

The typical response to the lowering of plasma Na⁺ concentration and blood pressure in our body involves the release of aldosterone from the adrenal glands, which triggers the reabsorption of sodium in the kidney. Although the effects of aldosterone on this physiological mechanism were extensively studied in the past decades, there are still some aspects to be fully elucidated. In the present study, we propose for the first time a new approach based on Raman spectroscopy to monitor the ionic activity in aldosterone-treated A6 renal epithelial cells. This spectroscopic technique is capable of probing the cells through their thickness in a non-destructive and nimble way. The spectroscopic variations of the Raman bands associated to the O-H stretching of water were correlated to the variations of ionic concentration in the intracellular and extracellular fluids. The increase of Na⁺ concentration gradients was clearly visualized in the cytosol of aldosterone-treated cells. The enhancement of the Na⁺ current density induced by aldosterone was estimated from the variation of the ionic chemical potential across the intracellular space. In addition, the variation of the O-H Raman bands of water was used to quantify the cell thickness, which was not affected by aldosterone.

Role of mineralocorticoid receptor antagonists in cardiovascular disease

Aldosterone exerts its best known sodium homeostasis actions by controlling sodium excretion at the level of the distal tubules via activation of the apical epithelial sodium channel and the basolateral Na(+)/K(+)ATPase pump. Recently, this mineralocorticoid hormone has been demonstrated to act on the heart and blood vessels. Excess release of aldosterone in relation to the salt status induces both genomic and nongenomic effects that by promoting endothelial dysfunction, and vascular and cardiorenal adverse remodeling, contribute to the target organ damage found in hypertension, heart failure, myocardial infarction, and chronic renal failure. Mineralocorticoid receptor blockers have been shown to be highly effective in resistant hypertension and to slow down heart failure progression, and in experimental animals, the development of atherosclerosis. Blockade of the action of aldosterone and potentially other mineralocorticoid steroids has been increasingly demonstrated to be an extremely beneficial therapy in different forms of cardiovascular disease. This review provides a summary of the knowledge that exists on aldosterone actions in the cardiovascular system and, in providing the translational impact of this knowledge to the clinical arena, illustrates how much more needs to be achieved in exploring the use of mineralocorticoid receptor blockers in less advanced stages of heart, renal, and vascular disease.

Cardiac effects of aldosterone: does gender matter?

Ischemic heart disease (IHD) continues to be the most common cause of death globally, although mortality rates are decreasing with significant advances in treatment. Higher prevalence of co-morbidities in women only partly explains the lack of decrease in mortality rates in younger women due to. Until recently there has been gender bias in pre-clinical studies and many clinical trials, resulting in a significant gap in knowledge whether there are differential responses to therapy for women, particularly younger women. There is increasing evidence that there are significant gender-specific differences in the outcome of post-infarction remodelling, prevalence of hypertension and sudden cardiac death. These differences indicate that cardiac tissue in females displays significant physiological and biochemical differences compared to males. However, the mechanisms mediating these differences, and how they change with age, are poorly understood. Circulating levels and physiological effects of aldosterone vary across the menstrual cycle suggesting female steroid sex hormones may not only regulate production of, but also responses to, aldosterone in pre-menopausal women. This modified tissue response may foster a homeostatic environment where higher levels of aldosterone are tolerated without adverse cardiac effect. Moreover, there is limited data on the direct regulation of this signalling axis by androgens in female animals/subjects. This review explores the relationship between gender and the effects of aldosterone in cardiovascular disease (CVD), an issue of significant need that may lead to changes in best practice to optimise clinical care and improve outcomes for females with CVD.

Regulation of cell volume and water transport--an old fundamental role of the renin angiotensin aldosterone system components at the cellular level

The expression and the role of renin angiotensin aldosterone system (RAAS) components on regulation of cell volume and water transport on vertebrates and invertebrates were reviewed. The presence of these components even in simple organisms like leeches and their relevance for the control of cellular volume and water transport supports the view that the expression of these components, at cellular level, is an acquisition which was preserved throughout evolution.

Evolution of hormone selectivity in glucocorticoid and mineralocorticoid receptors

Mineralocorticoid receptors (MR) and glucocorticoid receptors (GR) are descended from an ancestral corticoid receptor (CR). To date, the earliest CR have been found in lamprey and hagfish, two jawless fish (cyclostomes) that evolved at the base of the vertebrate line. Lamprey CR has both MR and GR activity. Distinct orthologs of the GR and MR first appear in skates and sharks, which are cartilaginous fishes (Chondrichthyes). Aldosterone, the physiological mineralocorticoid in terrestrial vertebrates, first appears in lobe-finned fish, such as lungfish and coelacanth, forerunners of terrestrial vertebrates, but not in sharks, skates or ray-finned fish. Skate MR are transcriptionally activated by glucocorticoids, such as corticosterone and cortisol, as well as by mineralocorticoids such as deoxycorticosterone and (experimentally) aldosterone; skate GR have low affinity for all human corticosteroids and 1α-OH-corticosterone, which has been proposed to be biologically active glucocorticoid. In fish, cortisol is both physiological mineralocorticoid and glucocorticoid; in terrestrial vertebrates, cortisol or corticosterone are the physiological glucocorticoids acting through GR, and aldosterone via MR as the physiologic mineralocorticoid. MR have equally high affinity for cortisol, corticosterone and progesterone. We review this evolutionary process through an analysis of changes in sequence and structure of vertebrate GR and MR, identifying changes in these receptors in skates and lobe-fined fish important in allowing aldosterone to act as an agonist at epithelial MR and glucocorticoid specificity for GR. hMR and hGR have lost a key contact between helix 3 and helix 5 that was present in their common ancestor. A serine that is diagnostic for vertebrate MR, and absent in terrestrial and fish GR, is present in lamprey CR, skate MR and GR, but not in coelacanth GR, marking the transition of the GR from MR ancestor. Based on the response of the CR and skate MR and GR to corticosteroids, we conclude that the mechanism(s) for selectivity of GR for cortisol and corticosterone and the specificity of aldosterone for MR are incompletely understood. This article is part of a Special Issue entitled 'CSR 2013'.

Evolving research in nongenomic actions of aldosterone

PURPOSE OF REVIEW

Aldosterone is now recognized as an increasingly important contributor to cardiometabolic pathology via inflammatory and fibrosis-related pathways in addition to its classically described role in sodium and volume regulation. Consequently, much effort has been directed towards characterizing the molecular pathways involved in aldosterone-mediated fibrosis and inflammation. What was once viewed as straightforward steroid hormone biology is now appreciated as a highly complex and tightly regulated series of pathways and interactions. These recognitions have fuelled a multidisciplinary effort to identify precisely how aldosterone mediates intracellular activation of both genomic (latent) and nongenomic (rapid) mechanisms of influence. This review will explore recent novel pathways regulating aldosterone action, focusing on the nongenomic pathways.

RECENT FINDINGS

Several recent discoveries have redefined our understanding of aldosterone interactions at the cellular level. This includes activation of the mineralocorticoid receptor at the plasma membrane instead of via classical nuclear hormone receptor interaction, and identification of novel cofactor scaffolding proteins that modify aldosterone influence at the cellular level. In addition, aldosterone activation of secondary messenger system cascades can occur directly and independent of mineralocorticoid receptor interaction.

SUMMARY

Substantial progress in detailing the molecular biology of aldosterone regulation and action should facilitate study of how it exerts detrimental effects in cardiometabolic diseases. However, to date, the clinical impact of these discoveries has not been validated. Translational efforts are now required to determine if novel therapeutic targets can be developed.

The mineralocorticoid signaling pathway throughout development: expression, regulation and pathophysiological implications

The mineralocorticoid signaling pathway has gained interest over the past few years, considering not only its implication in numerous pathologies but also its emerging role in physiological processes during kidney, brain, heart and lung development. This review aims at describing the setting and regulation of aldosterone biosynthesis and the expression of the mineralocorticoid receptor (MR), a nuclear receptor mediating aldosterone action in target tissues, during the perinatal period. Specificities concerning MR expression and regulation during the development of several major organs are highlighted. We provide evidence that MR expression is tightly controlled in a tissue-specific manner during development, which could have major pathophysiological implications in the neonatal period.

Central regulation of blood pressure by the mineralocorticoid receptor

Addition of mineralocorticoid receptor (MR) antagonists to standard therapy for heart failure, kidney disease, metabolic syndrome, and diabetes is increasing steadily in response to clinical trials demonstrating clear benefits. In addition to blocking deleterious activity of MR within the heart, vessels and kidneys, MR antagonists target MR in hemodynamic regulatory centers in the brain, thereby decreasing excessive sympathetic nervous system drive, vasopressin release, abnormal baroreceptor function, and circulating and tissue pro-inflammatory cytokines. However, brain MR are also involved with cognition, memory, affect and functions yet to be determined. Understanding specific central mechanisms involved in blood pressure regulation by MR is necessary for the development of agents to target downstream events specific to central hemodynamic regulation, not only to avoid the hypokalemia caused by inhibition of renal tubular MR, but also to avoid untoward long term effects of inhibiting brain MR that are not involved in blood pressure control.

Aldosterone and mineralocorticoid receptors: a personal reflection

Since the isolation and characterization of aldosterone in 1953, subsequent developments in the field can be neatly considered over three time spans, each of two decades. In the first aldosterone itself was the primary focus; from 1973, for two decades the mineralocorticoid receptor (MR) was the front runner; since 1993 the focus has been on both, with aldosterone being discovered by cardiologists, and distinguished within their panoply of neurohumoral factors.

The mislabelling of deoxycorticosterone: making sense of corticosteroid structure and function

Over the 70 or so years since their discovery, there has been continuous interest and activity in the field of corticosteroid functions. However, despite major advances in the characterisation of receptors and coregulators, in some ways we still lack clear insight into the mechanism of receptor activation, and, in particular, the relationship between steroid hormone structure and function remains obscure. Thus, why should deoxycorticosterone (DOC) reportedly be a weak mineralocorticoid, while the addition of an 11β-hydroxyl group produces glucocorticoid activity, yet further hydroxylation at C18 leads to the most potent mineralocorticoid, aldosterone? This review aims to show that the field has been confused by the misreading of the earlier literature and that DOC, far from being relatively inactive, in fact has a wide range of activities not shared by the other corticoids. In contrast to the accepted view, the presence of an 11β-hydroxyl group yields, in corticosterone or cortisol, hormones with more limited functions, and also more readily regulated, by 11β-hydroxysteroid dehydrogenase. This interpretation leads to a more systematic understanding of structure-function relationships in the corticosteroids and may assist more rational drug design.

Effects of aldosterone on coronary function

Our understanding of the effects of aldosterone and its mechanisms has increased substantially in recent years, probably because of the importance of the mineralocorticoid receptor (MR) antagonists in several major cardiovascular diseases. Recent clinical studies have confirmed the benefits of MR antagonists in patients with heart failure, left ventricular dysfunction after myocardial infarction, hypertension or diabetic nephropathy. However, it would be a gross oversimplification to conclude that the role of aldosterone is unequivocally negative. Aldosterone is synthesized in the adrenal glands and binds to specific MRs in target epithelial cells. The steroid-receptor complex penetrates the cell nucleus where it modulates gene expression and activates specific aldosterone-induced proteins that control sodium reabsorption. Recent studies have shown that aldosterone also impacts a wide range of non-epithelial tissues such as the heart and blood vessels. Remarkably, aldosterone can also be synthesized in extra-adrenal tissues and it may act in a rapid non-genomic manner.We note the existence of glucocorticoids that exhibit plasma concentrations much higher than those of aldosterone and that are structurally very similar to aldosterone. It is thus possible that glucocorticoids may bind to the aldosterone receptor in some cell types. Diverse experimental models and several strains of transgenic mice have allowed us to better understand the effects of aldosterone on the heart. Specifically, it seems that a slight increase in cardiac aldosterone concentrations induces a decreased coronary reserve in mice by decreasing the BKCa potassium channels associated with coronary smooth muscle cells. Taken together, these experiments indicate that vascular cells are the primary targets of aldosterone in the cardiovascular system. The hormone directly affects NO and EDHF-mediated coronary relaxation. Both mechanisms may contribute to the deleterious cardiovascular effects of MR stimulation.

A lifetime of aldosterone excess: long-term consequences of altered regulation of aldosterone production for cardiovascular function

Up to 15% of patients with essential hypertension have inappropriate regulation of aldosterone; although only a minority have distinct adrenal tumors, recent evidence shows that mineralocorticoid receptor activation contributes to the age-related blood pressure rise and illustrates the importance of aldosterone in determining cardiovascular risk. Aldosterone also has a major role in progression and outcome of ischemic heart disease. These data highlight the need to understand better the regulation of aldosterone synthesis and its action. Aldosterone effects are mediated mainly through classical nuclear receptors that alter gene transcription. In classic epithelial target tissues, signaling mechanisms are relatively well defined. However, aldosterone has major effects in nonepithelial tissues that include increased synthesis of proinflammatory molecules and reactive oxygen species; it remains unclear how these effects are controlled and how receptor specificity is maintained. Variation in aldosterone production reflects interaction of genetic and environmental factors. Although the environmental factors are well understood, the genetic control of aldosterone synthesis is still the subject of debate. Aldosterone synthase (encoded by the CYP11B2 gene) controls conversion of deoxycorticosterone to aldosterone. Polymorphic variation in CYP11B2 is associated with increased risk of hypertension, but the molecular mechanism that accounts for this is not known. Altered 11beta-hydroxylase efficiency (conversion of deoxycortisol to cortisol) as a consequence of variation in the neighboring gene (CYP11B1) may be important in contributing to altered control of aldosterone synthesis, so that the risk of hypertension may reflect a digenic effect, a concept that is discussed further. There is evidence that a long-term increase in aldosterone production from early life is determined by an interaction of genetic and environmental factors, leading to the eventual phenotypes of aldosterone-associated hypertension and cardiovascular damage in middle age and beyond. The importance of aldosterone has generated interest in its therapeutic modulation. Disadvantages associated with spironolactone (altered libido, gynecomastia) have led to a search for alternative mineralocorticoid receptor antagonists. Of these, eplerenone has been shown to reduce cardiovascular risk after myocardial infarction. The benefits and disadvantages of this therapeutic approach are discussed.

Pomc knockout mice have secondary hyperaldosteronism despite an absence of adrenocorticotropin

Aldosterone production is controlled by angiotensin II, potassium, and ACTH. Mice lacking Pomc and its pituitary product ACTH have been reported to have absent or low aldosterone levels, suggesting that ACTH is required for normal aldosterone production. However, this is at odds with the clinical finding that human aldosterone deficiency is not a component of secondary adrenal insufficiency. To resolve this, we measured plasma and urine electrolytes, together with plasma aldosterone and renin activity, in Pomc(-/-) mice. We found that these mice have secondary hyperaldosteronism (elevated aldosterone without suppression of renin activity), indicating that ACTH is not required for aldosterone production or release in vivo. Exogenous ACTH stimulates a further increase in aldosterone in Pomc(-/-) mice, whereas angiotensin II has no effect, and the combination of angiotensin II and ACTH is no more potent than ACTH alone. These data suggest that aldosterone production and release in vivo do not require the action of ACTH during development or postnatal life and that secondary hyperaldosteronism in Pomc(-/-) mice is a consequence of glucocorticoid deficiency.

Drug Insight: eplerenone, a mineralocorticoid-receptor antagonist

Increasing recognition of the role of aldosterone in cardiovascular disease has been supported by a significant body of evidence from animal models. This evidence has been translated into clinical practice, and large-scale, randomized, placebo-controlled trials have confirmed the beneficial effects of mineralocorticoid blockade in patients with heart failure. As a consequence, there has been a resurgence in the use of mineralocorticoid-receptor antagonists in clinical practice that has prompted the search for a potent and specific antagonist without the sexual side effects of spironolactone. Eplerenone, a mineralocorticoid-receptor antagonist with minimal binding to the progesterone and androgen receptors, is now licensed for treatment of heart failure in Europe and heart failure and hypertension in the US; it has also been proposed as a treatment for a variety of cardiovascular conditions. This article reviews the current concepts of the actions of aldosterone at a cellular level. Recent findings regarding its role as a cardiovascular hormone, both in animal models and human studies, are discussed. We also describe the development of mineralocorticoid-receptor blockers following the isolation of aldosterone and discuss the subsequent search for a specific mineralocorticoid antagonist. In addition we detail the effects of eplerenone in a number of clinical situations and outline its potential future applications.

Fiftieth anniversary of aldosterone: from discovery to cardiovascular therapy

Half a century after the elucidation of its molecular structure, aldosterone is generating the greatest interest, not in the fields of endocrinology or renal medicine but in cardiology-where aldosterone over-activation is now perceived as detrimental in heart failure (HF) and ischaemic heart disease. Clinically, excess aldosterone is associated with higher morbidity and mortality after myocardial infarction (MI) and HF. The Randomised Aldactone Evaluation Study (RALES) study in severe chronic heart failure and the Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival (EPHESUS) study in post-MI heart failure have shown that use of non-selective and selective aldosterone receptor antagonists, respectively, improves prognosis. The pathophysiological mechanisms underpinning these damaging aldosterone-mediated cardiovascular effects are still being elucidated, but prime candidates include cardiomyocyte necrosis and apoptosis, and myocardial fibrosis resulting in adverse cardiac remodelling, coronary vasculopathy, tachyarrhythmia and positive feedback activation of the renin-angiotensin-aldosterone system. Practical points for consideration when instigating therapy include preferential use of aldosterone receptor antagonists to maintain electrolyte balance whenever loop or thiazide diuretics are used (vulnerable HF patients require higher ranges of potassium and magnesium to minimise propensity for tachyarrthythmia), for renoprotection and for counteracting aldosterone breakthrough despite adequate ACE inhibition; use of the minimum doses of loop diuretics required to lessen activation of the renin-angiotensin-aldosterone system in HF; use of selective aldosterone receptor antagonists to avoid gynaecomastia/mastalgia and impotence; and prophylactic use of aldosterone receptor antagonists to improve prognosis.