eplerenone and Fibrosis

Cardiovascular and renal diseases are one of the main health problems in all industrialized countries. Their incidence is constantly increasing due to the aging of the population and the greater prevalence of obesity and type 2 diabetes. Clinical evidence suggests that aldosterone and the activation of mineralocorticoid receptors (MR) have a role in the pathophysiology of cardiovascular and renal diseases. Moreover, clinical studies demonstrate the benefits of mineralocorticoid receptor antagonists (MRAs) on mortality and progression of heart and kidney disease. In addition to renal effects on body fluid homeostasis, aldosterone has multiple extrarenal effects including the induction of inflammation, vascular rigidity, collagen formation and stimulation of fibrosis. Given the fundamental role of MR activation in renal and cardiac fibrosis, effective and selective blocking of the signal with MRAs can be used in the clinical practice to prevent or slow down the progression of heart and kidney diseases. The aim of the present work is to review the role of MRAs in light of the new evidence as well as its potential use as an antifibrotic in chronic kidney disease (CKD). The initial clinical results suggest that MRAs are potentially useful in treating patients with chronic kidney disease, particularly in cases of diabetic nephropathy. We don't yet have efficacy and safety data on the progression of kidney disease up to the end stage (ESRD) and filling this gap represents an important target for future trials.

Topics: Aldosterone; Body Fluids; Cardiovascular Diseases; Clinical Trials as Topic; Cytokines; Diabetic Nephropathies; Eplerenone; Fibrosis; Heart; Heart Diseases; Homeostasis; Humans; Kidney; Mineralocorticoid Receptor Antagonists; Naphthyridines; Receptors, Mineralocorticoid; Renal Insufficiency, Chronic; Spironolactone

The role of the renin-angiotensin-aldosterone system (RAAS) in hypertension has since long been recognized and aldosterone has been acknowledged as one of the key hormones in the pathophysiology, not only in primary aldosteronism but also in essential hypertension and drug-resistant hypertension. Aldosterone-receptor antagonists (ARAs) are increasingly used in patients with resistant hypertension, often with impressive results. However, definitive evidence for the benefit of ARAs in these patients from randomized, controlled trials is lacking. This review gives an overview of the current data on this topic. Future studies should focus on the identification of factors that are able to predict the response to treatment, as to select patients who will benefit most from treatment with ARAs. On the basis of the current knowledge, we recommend prescription of ARAs to patients with primary aldosteronism, resistant hypertension and patients with hypertension and hypokalemia.

Topics: Albuminuria; Aldosterone; Angiotensin-Converting Enzyme Inhibitors; Animals; Arrhythmias, Cardiac; Drug Therapy, Combination; Electrocardiography; Eplerenone; Fibrosis; Glomerular Filtration Rate; Humans; Hypertension; Hypertrophy, Left Ventricular; Mineralocorticoid Receptor Antagonists; Myocardium; Spironolactone

Fifty years after its discovery, aldosterone continues to stimulate interest as a therapeutic target. Early studies focused on aldosterone's actions on hypertension, the kidney, and electrolyte handling. More recently, its actions on the heart and cardiovascular system have become more apparent. Aldosterone causes cardiac fibrosis and remodeling, and stimulates neurohormonal systems that adversely affect the cardiovascular system. Aldosterone antagonism attenuates these negative effects. Clinical studies have applied this science and demonstrated improved morbidity and mortality with aldosterone blockade, specifically in patients with chronic heart failure and patients who are postmyocardial infarction and with depressed left ventricular function. This article will address the pathophysiology of aldosterone in cardiac fibrosis and remodeling, review the current clinical trial data, and explore the application of aldosterone blockade in an expanded heart failure population. The Randomized Aldactone Evaluation Study showed that the aldosterone antagonist spironolactone reduced mortality when compared to placebo in patients with chronic advanced heart failure. Similarly, the Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study demonstrated a significant reduction in mortality and hospitalizations for patients randomized to the aldosterone antagonist eplerenone. A more provocative question is whether aldosterone antagonism will afford the same protection in patient populations with heart failure and preserved left ventricular function. Clinical trials are underway, and results are eagerly awaited.

Topics: Aldosterone; Cardiovascular Agents; Drug Therapy, Combination; Eplerenone; Fibrosis; Heart Failure; Humans; Mineralocorticoid Receptor Antagonists; Myocardium; Spironolactone; Treatment Outcome; Ventricular Dysfunction, Left; Ventricular Remodeling

Recent clinical and pre-clinical studies have indicated the utility of mineralocorticoid receptor (MR) antagonists in renal injury. We have demonstrated in rats that chronic treatment with aldosterone results in severe proteinuria and renal injury, characterized by glomerular changes, tubulointerstitial fibrosis, and collagen accumulation. We also observed increased reactive oxygen species (ROS) generation and mitogen-activated protein kinases (MAPKs) activity in renal cortical tissues. Treatment with a selective MR antagonist, eplerenone, prevented elevation of ROS levels and MAPK activity, as well as ameliorating renal injury. In vitro studies revealed that MRs are highly expressed in rat glomerular mesangial cells (RMC) and rat renal fibroblasts. In RMC, aldosterone induces cellular injuries through NADPH oxidase-dependent ROS production and/or MAPK activation. Aldosterone-induced renal cellular injuries were markedly attenuated by treatment with eplerenone. These data suggest that aldosterone induces renal injury through activation of MRs and support the notion that MR blockade has beneficial effects on aldosterone-dependent renal injury through mechanisms that cannot be simply explained by hemodynamic changes. In this review, we summarized our recent findings pertaining to the roles of aldosterone and MRs in the pathogenesis of renal injury. Potential molecular mechanisms responsible for aldosterone/MR-induced renal injury were also discussed.

Topics: Aldosterone; Animals; Cell Proliferation; Cell Shape; Cells, Cultured; Collagen; Eplerenone; Fibroblasts; Fibrosis; Humans; Kidney; Kidney Diseases; Mesangial Cells; Mineralocorticoid Receptor Antagonists; Mitogen-Activated Protein Kinases; Rats; Reactive Oxygen Species; Receptors, Mineralocorticoid; Spironolactone

Topics: Aldosterone; Animals; Cardiovascular Diseases; Endothelium, Vascular; Epithelial Sodium Channels; Eplerenone; Fibrosis; Humans; Mineralocorticoid Receptor Antagonists; Muscle, Smooth, Vascular; Myocardium; Oxidative Stress; Receptors, Mineralocorticoid; Sodium Channels; Sodium-Potassium-Exchanging ATPase; Sodium, Dietary; Spironolactone

In recent years, there has been a striking paradigm shift with respect to our understanding of the widespread effects of aldosterone. Whereas the role of angiotensin II in mediating progressive renal disease and heart failure has been documented extensively, more recent evidence has implicated aldosterone as an important pathogenetic factor in addition to angiotensin II in the development of these diseases. The focus of this review is aldosterone and progressive renal dysfunction. The extensive preclinical and clinical evidence supporting the efficacy of aldosterone blockade in abrogating proteinuria is summarized. The frequency and clinical importance of aldosterone "escape" is reviewed. Therapeutic considerations to reduce the incidence of hyperkalemia with aldosterone blockade are discussed. The studies reviewed have several important clinical implications for considering new treatment algorithms for patients with incipient nephropathy. Because full doses of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers attenuate but do not abrogate progression of renal dysfunction, add-on aldosterone blockade therapy may constitute a rational therapeutic strategy for retarding progression of renal disease.

Topics: Aldosterone; Algorithms; Disease Progression; Disease Susceptibility; Drug Labeling; Eplerenone; Fibrosis; Heart Failure; Humans; Hyperkalemia; Kidney; Mineralocorticoid Receptor Antagonists; Renal Agents; Renal Insufficiency; Spironolactone

Topics: Aldosterone; Chronic Disease; Death, Sudden, Cardiac; Diuretics; Eplerenone; Fibrosis; Heart Failure; Humans; Mineralocorticoid Receptor Antagonists; Myocardium; Randomized Controlled Trials as Topic; Spironolactone; Sulfonamides; Torsemide; Ventricular Remodeling

Prolonged overactivation of neurohormonal mechanisms in heart failure produces deleterious effects on the cardiovascular system and leads to poor prognosis. Angiotensin-converting enzyme (ACE) inhibitors and beta-blockers have been shown to interrupt this excessive overactivity and improve survival. Activation of the renin-angiotensin system leads to increased synthesis of aldosterone in heart failure. Some aldosterone production is independent of ACEs; therefore, ACE inhibition does not entirely suppress the excessive formation of aldosterone. An excess of aldosterone in heart failure leads to sodium retention and myocardial fibrosis. The use of aldosterone antagonists, combined with standard therapy for heart failure, improves morbidity and mortality.

Topics: Aldosterone; Eplerenone; Fibrosis; Heart Failure; Humans; Mineralocorticoid Receptor Antagonists; Myocardium; Spironolactone

Angiotensin converting enzyme (ACE) inhibitor therapy does not reliably suppress aldosterone production, and 'aldosterone escape' occurs in up to 40% of patients with congestive heart failure (CHF). Aldosterone levels correlate with the risk of cardiovascular events. Aldosterone adversely affects the risk of cardiovascular events via mineralocorticoid receptors in the heart, blood vessels and other sites. Notably, aldosterone contributes to endothelial dysfunction and attenuates endothelium-dependent vasodilatation, at least partly by reducing nitric oxide bioavailability. Aldosterone also promotes myocardial fibrosis and cardiac remodelling by enhancing collagen synthesis, resulting in increased myocardial stiffness and increased left ventricular mass. These mechanisms mediated by aldosterone contribute to increased risk of ventricular arrhythmias and sudden cardiac death. Two major prospective trials, including one in which patients routinely received ACE inhibitor and beta blocker therapy, have shown that the use of an aldosterone blocker significantly reduces all-cause mortality, sudden cardiovascular death and hospitalisation in patients with acute or chronic left ventricular dysfunction or CHF. Inhibition of aldosterone's effect on mineralocorticoid receptors should now be considered standard therapy in these patient populations.

Topics: Aldosterone; Angiotensin-Converting Enzyme Inhibitors; Death, Sudden, Cardiac; Endothelium, Vascular; Eplerenone; Fibrosis; Heart Failure; Humans; Myocardium; Spironolactone; Ventricular Remodeling

Topics: Aldosterone; Animals; Cardiomegaly; Clinical Trials as Topic; Desoxycorticosterone; Eplerenone; Fibrosis; Heart; Heart Failure; Humans; Hypertension; Mineralocorticoid Receptor Antagonists; Myocardium; Rats; Rats, Inbred SHR; Receptors, Mineralocorticoid; Spironolactone

Activation of the mineralocorticoid receptor (MR) may promote dysfunctional adipose tissue in patients with type 2 diabetes, where increased pericellular fibrosis has emerged as a major contributor. The knowledge of the association among the MR, fibrosis, and the effects of an MR antagonist (MRA) in human adipocytes remains very limited. The present substudy, including 30 participants, was prespecified as part of the Mineralocorticoid Receptor Antagonist in Type 2 Diabetes (MIRAD) trial, which randomized patients to either high-dose eplerenone or placebo for 26 weeks. In adipose tissue biopsies, changes in fibrosis were evaluated by immunohistological examination and by the expression of mRNA and protein markers of fibrosis. Treatment with an MRA reduced pericellular fibrosis, synthesis of the major subunits of collagen types I and VI, and the profibrotic factor α-smooth muscle actin compared with placebo in subcutaneous adipose tissue. Furthermore, we found decreased expression of the MR and downstream molecules neutrophil gelatinase-associated lipocalin, galectin-3, and lipocalin-like prostaglandin D2 synthase with an MRA. In conclusion, we present original data demonstrating reduced fibrosis in adipose tissue with inhibition of the MR, which could be a potential therapeutic approach to prevent the extracellular matrix remodeling of adipose tissue in type 2 diabetes.

Topics: Actins; Aged; Collagen Type I; Collagen Type VI; Diabetes Mellitus, Type 2; Eplerenone; Female; Fibrosis; Humans; Male; Middle Aged; Mineralocorticoid Receptor Antagonists; Subcutaneous Fat

Eplerenone is reported to reduce the development of atrial fibrillation (AF). The aim of this study was to clarify the mechanism of eplerenone for AF prevention from the viewpoint of P wave morphology, which is reported to correlate with atrial fibrosis.. Thirty-five patients with hypertension, who were randomized to receive eplerenone (n = 16) or amlodipine (n = 19) for 1 year, were evaluated. P wave signal-averaged electrocardiography was recorded at baseline and 1 year after entry, and P wave duration (Ad) and P wave dispersion (P-disp) were obtained. Serum levels of intact procollagen type I N-terminal propeptide (PINP) and N-terminal procollagen-III peptide (PIIIP) were also measured.. There were no significant differences in baseline clinical characteristics including Ad, P-disp, and the decrease in blood pressure at 1-year follow-up between the two groups. Ad and P-disp (mean ± standard deviation) significantly increased in patients on amlodipine after 1 year (140 ± 21 ms to 139 ± 19 ms vs 132 ± 10 ms to 136 ± 12 ms, P < 0.01 and 14 ± 7 ms to 9 ± 4 ms vs 12 ± 5 to 16 ± 8, P < 0.01, respectively). PINP was significantly more decreased in patients with eplerenone than amlodipine (56.6 ± 30.4 μg/mL to 46.6 ± 19.4 μg/mL vs 41.5 ± 16.2 μg/L to 48.7 ± 21.3 μg/L, P < 0.01). Percent changes of Ad, P-disp, PINP, and PIIIP were significantly smaller in patients with eplerenone than amlodipine (0.0 ± 4.7% vs 3.2 ± 4.4%, P < 0.05, - 28.6 ± 31.0% vs 46.3 ± 73.0%, P < 0.01, - 5.6 ± 38.1% vs 22.7 ± 42.7%, P < 0.05, and - 9.2 ± 25.1% vs 7.4 ± 19.0%, P < 0.05, respectively).. Eplerenone reduced the increase of Ad and P-disp with a decrease of PINP and PIIIP, which might translate into reduction of atrial fibrosis. This study showed that eplerenone may be useful as upstream therapy for AF in patients with hypertension.

Topics: Aged; Atrial Fibrillation; Electrocardiography; Eplerenone; Female; Fibrosis; Heart Atria; Humans; Hypertension; Male; Mineralocorticoid Receptor Antagonists; Spironolactone

There is no proven pharmacological strategy for the treatment of the failing systemic right ventricle (SRV) but myocardial fibrosis may play a role in its pathophysiology.. We designed a double-blind, placebo-controlled clinical trial to assess the effects of eplerenone 50mg during 12 months on cardiac magnetic resonance parameters (SRV mass and ejection fraction) and neurohormonal and collagen turnover biomarker (CTB) levels.. Twenty six patients with atrial switch repair for transposition of the great arteries were randomized to eplerenone (n=14) or placebo (n=12) and 14 healthy volunteers served as controls for comparison of baseline neurohormones and CTB levels. The study population showed a good baseline profile in terms of SRV mass (57.4 ± 17 g/m(2)) and ejection fraction (54.9 ± 7.5%). However, levels of N-terminal pro-brain natriuretic peptide (NT-proBNP), C terminal propeptide of type I procollagen (CICP) and C-terminal Telopeptide of type I Collagen (ICTP) were significantly elevated when compared to healthy controls. After one year of treatment, a trend toward reduction of CICP, N-terminal pro-Matrix Metalloproteinase 1 (NT-proMMP1), Tissue Inhibitor of Metalloproteinases 1 (TIMP1) and galectin 3 levels and a lower increase in ICTP in patients under eplerenone was observed. The reduction of SRV mass and the improvement of SRV function with eplerenone were not conclusive.. Patients with SRV treated with eplerenone showed an improvement of an altered baseline CTB profile suggesting that reduction of myocardial fibrosis might be a therapeutic target in these patients.

Topics: Adult; Aldosterone; Cardiac Imaging Techniques; Collagen; Double-Blind Method; Eplerenone; Female; Fibrosis; Follow-Up Studies; Heart Failure; Humans; Magnetic Resonance Imaging; Male; Mineralocorticoid Receptor Antagonists; Myocardium; Spironolactone; Transposition of Great Vessels; Treatment Outcome; Ventricular Dysfunction, Right; Young Adult

Development of a cardiomyopathy in diabetes mellitus is independent of traditional risk factors, with no clinical trials targeting specific therapeutic interventions. Myocardial fibrosis is one of the key mechanisms and aldosterone is a key mediator of myocardial fibrosis. We propose that aldosterone antagonism will improve cardiac function. We aim to evaluate the efficacy of selective aldosterone receptor antagonism with eplerenone added to optimal medical treatment in improving cardiac structure and function in diabetic cardiomyopathy. We will randomize 130 patients with type 2 diabetes mellitus, stable metabolic control and impaired left ventricular (LV) systolic or diastolic function, to either eplerenone (target dose 50mg) or matching placebo, in addition to optimal medical therapy for 12 months. The primary endpoints are changes in LV systolic and diastolic function, measured by echocardiographic 2-dimensional speckle tracking strain and strain rate and tissue Doppler imaging. The secondary endpoints include changes in echocardiographic markers and plasma biomarkers of collagen turnover; left atrial dimensions and function, incidence of atrial fibrillation and changes in exercise capacity and dyspnea score. The present study will assess whether specific aldosterone antagonism with eplerenone in addition to standard therapy will prevent progression or reverse cardiac dysfunction in diabetic cardiomyopathy using sensitive, robust and quantifiable echocardiographic measures that allow early detection of change. The study may offer a new direction in the management of this condition.. ACTRN12610001063000.

Topics: Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Cardiovascular Agents; Clinical Protocols; Collagen; Diabetes Mellitus, Type 2; Diabetic Cardiomyopathies; Diastole; Double-Blind Method; Drug Therapy, Combination; Echocardiography, Doppler; Eplerenone; Fibrosis; Humans; Mineralocorticoid Receptor Antagonists; Myocardium; New South Wales; Prospective Studies; Recovery of Function; Research Design; Spironolactone; Systole; Time Factors; Treatment Outcome; Ventricular Function, Left

Topics: Aldosterone; Animals; Cardiomegaly; Eplerenone; Fibrosis; Male; Mice; Mice, Transgenic; Myocytes, Cardiac; Transforming Growth Factor beta1; Ventricular Remodeling

Cardiorenal syndrome (CRS) is the leading cause of death associated with chronic kidney disease (CKD) and end-stage renal disease (ESRD). However, the underlying mechanisms of CRS are still poorly understood. Here, we studied a CKD model of unilateral ureteral obstruction (UUO) and observed pathological cardiac fibrosis and lymphangiogenesis in 180-day old UUO rats, in which inflammatory injury plays a major role. In addition, treatment of UUO rats with eplerenone, a mineralocorticoid receptor blocker (MRB), significantly reduced cardiac lymphangiogenesis and fibrosis. In conclusion, our experimental results showed that cardiac lymphangiogenesis in long-term UUO rats may be involved in the formation of cardiac fibrosis and that eplerenone can alleviate lymphangiogenesis and cardiac fibrosis by inhibiting inflammation.

Topics: Animals; Disease Models, Animal; Eplerenone; Fibrosis; Kidney; Lymphangiogenesis; Rats; Renal Insufficiency, Chronic; Ureteral Obstruction

Renal fibrosis is the inevitable pathway of the progression of chronic kidney disease to end-stage renal disease, which manifests as progressive glomerulosclerosis and renal interstitial fibrosis. In a previous study, we observed severe interstitial fibrosis in the contralateral kidneys of 6-month unilateral ureteral obstruction (UUO) rats, which was accompanied by increased macrophage infiltration and phenotypic transformation; after eplerenone administration, these effects were reduced. Therefore, we hypothesized that this effect was closely related to mineralocorticoid receptor (MR) activation induced by the increased aldosterone (ALD) level. In this study, we used uninephrectomy plus continuous aldosterone infusion in mice to observe whether aldosterone induced macrophage-to-myofibroblast transition (MMT) and renal fibrosis and investigated the signaling pathways. Notably, aldosterone induced predominantly M1 macrophage-to-myofibroblast transition by activating MR and upregulating TGF-β1 expression, which promoted renal fibrosis. These effects were antagonized by the MR blocker esaxerenone. These findings suggest that targeting the MR/TGF-β1 pathway may be an effective therapeutic strategy for renal fibrosis.

Topics: Aldosterone; Animals; Eplerenone; Fibrosis; Macrophages; Mice; Myofibroblasts; Pyrroles; Rats; Receptors, Mineralocorticoid; Renal Insufficiency, Chronic; Sulfones; Transforming Growth Factor beta1

Cardiovascular disease constitutes the leading cause of mortality in patients with chronic kidney disease (CKD), which is termed cardiorenal syndrome type 4 (CRS-4). Here, we report the development of pathological cardiac remodeling and fibrosis in unilateral urinary obstruction (UUO) rats.. Hematoxylin and eosin (H&E) staining was performed to observe the pathology of myocardial tissue. The degree of myocardial tissue fibrosis was observed by Masson and Sirius red staining. Immunohistochemical staining was applied to detect the expression of CD34 and CD105 in myocardial tissue, and immunofluorescent staining was performed to examine the expression of CD34, collagen I/collagen III, and alpha smooth muscle actin (. The results showed the development of pathological cardiac remodeling and cardiac dysfunction in UUO rats. Moreover, there was more angiogenesis and endothelial-mesenchymal transition (End-MT) in the UUO group, and these effects were inhibited by eplerenone.

Topics: Actins; Aldosterone; Animals; Collagen; Eosine Yellowish-(YS); Eplerenone; Fibrosis; Glucocorticoids; Hematoxylin; Interleukin-1beta; Kidney; NF-kappa B; Rats; Rats, Sprague-Dawley; Receptors, Mineralocorticoid; Renal Insufficiency, Chronic; RNA, Messenger; Ureteral Obstruction; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factor Receptor-2; Ventricular Remodeling

Cardiovascular complications are the leading causes of death in patients with chronic kidney disease (CKD), accounting for approximately 50% of deaths. Despite significant advances in the understanding of cardiac disease due to CKD, the underlying mechanisms involved in many pathological changes have not been fully elucidated. In our previous study, we observed severe fibrosis in the contralateral kidney of a 6-month-old rat UUO model. In the present experiment, we also observed severe fibrosis in the hearts of rats subjected to UUO and the macrophage-to-myofibroblast transition (MMT). These effects were inhibited by the mineralocorticoid receptor (MR) blocker eplerenone. Notably, in vitro, aldosterone-activated MR induced the MMT and subsequently promoted the secretion of CTGF, the target of MR, from macrophages; these changes were inhibited by eplerenone. The CTGF also induced the MMT and both the aldosterone and CTGF-induced MMT could be alleviated by the CTGF blocker. In conclusion, our results suggest that targeting the MR/CTGF pathway to inhibit the MMT may be an effective therapeutic strategy for the treatment of cardiac fibrosis.

Topics: Aldosterone; Animals; Cardio-Renal Syndrome; Eplerenone; Fibrosis; Heart Diseases; Macrophages; Myofibroblasts; Rats; Receptors, Mineralocorticoid; Renal Insufficiency, Chronic

Topics: Animals; Arrhythmias, Cardiac; Calcium Signaling; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Disease Models, Animal; Eplerenone; Female; Fibrosis; Male; Mice; Mice, Inbred C57BL; Mineralocorticoid Receptor Antagonists; Receptors, Mineralocorticoid; Signal Transduction; Smad3 Protein; Transforming Growth Factor beta

After myocardial infarction complicated by heart failure or diabetes, eplerenone (compared to placebo) significantly decreases amino-terminal propeptide of type III procollagen (PIIINP). Determining the subset of patients who are more prone to have a decrease in PIIINP and those who may respond better to the anti-fibrotic effects of mineralocorticoid receptor antagonists (MRA) therapy may be relevant for a personalized treatment approach. The aim of this study is to identify predictors of a PIIINP decrease and assess potential subgroups of "responders" to eplerenone.. Clinical factors and biomarkers were evaluated as predictors of a PIIINP decrease from randomization to month 9 in 323 patients from the biomarker substudy of Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study (EPHESUS). Additionally, the association between PIIINP decrease and the composite of cardiovascular (CV) death or CV hospitalization were also explored. External validation was performed in the REMINDER trial.. In patients who had a myocardial infarction, clinical factors used in combination and treatment with eplerenone were associated with a PIIINP decrease. Interestingly, higher randomization PIIINP levels might help in identifying patients more prone to have an "anti-fibrotic response" when treated with MRAs. Predictors of an antifibrotic response after MI complicated by HF. Several clinical factors and biomarkers predicted a PIIINP decrease after an MI complicated by HF. There was a significant interaction between baseline PIIINP levels and eplerenone treatment: patients with baseline PIIINP ≥ 3.6 mmol/L treated with eplerenone had the best response (PIIINP decrease).

Topics: Aged; Biomarkers; Clinical Decision-Making; Eplerenone; Female; Fibrosis; Heart Failure; Humans; Male; Middle Aged; Mineralocorticoid Receptor Antagonists; Myocardium; Patient Selection; Peptide Fragments; Predictive Value of Tests; Procollagen; Randomized Controlled Trials as Topic; Reproducibility of Results; Risk Factors; ST Elevation Myocardial Infarction; Time Factors; Treatment Outcome; Ventricular Remodeling

Increased activation of the renin-angiotensin-aldosterone system (RAAS) and elevated growth factor production are of crucial importance in the development of renal fibrosis leading to diabetic kidney disease. The aim of this study was to provide evidence for the antifibrotic potential of RAAS inhibitor (RAASi) treatment and to explore the exact mechanism of this protective effect. We found that RAASi ameliorate diabetes-induced renal interstitial fibrosis and decrease profibrotic growth factor production. RAASi prevents fibrosis by acting directly on proximal tubular cells, and inhibits hyperglycaemia-induced growth factor production and thereby fibroblast activation. These results suggest a novel therapeutic indication and potential of RAASi in the treatment of renal fibrosis.. In diabetic kidney disease (DKD) increased activation of renin-angiotensin-aldosterone system (RAAS) contributes to renal fibrosis. Although RAAS inhibitors (RAASi) are the gold standard therapy in DKD, the mechanism of their antifibrotic effect is not yet clarified. Here we tested the antifibrotic and renoprotective action of RAASi in a rat model of streptozotocin-induced DKD. In vitro studies on proximal tubular cells and renal fibroblasts were also performed to further clarify the signal transduction pathways that are directly altered by hyperglycaemia. After 5 weeks of diabetes, male Wistar rats were treated for two more weeks per os with the RAASi ramipril, losartan, spironolactone or eplerenone. Proximal tubular cells were cultured in normal or high glucose (HG) medium and treated with RAASi. Platelet-derived growth factor (PDGF) or connective tissue growth factor (CTGF/CCN2)-induced renal fibroblasts were also treated with various RAASi. In diabetic rats, reduced renal function and interstitial fibrosis were ameliorated and elevated renal profibrotic factors (TGFβ1, PDGF, CTGF/CCN2, MMP2, TIMP1) and alpha-smooth muscle actin (αSMA) levels were decreased by RAASi. HG increased growth factor production of HK-2 cells, which in turn induced activation and αSMA production of fibroblasts. RAASi decreased tubular PDGF and CTGF expression and reduced production of extracellular matrix (ECM) components in fibroblasts. In proximal tubular cells, hyperglycaemia-induced growth factor production increased renal fibroblast transformation, contributing to the development of fibrosis. RAASi, even in non-antihypertensive doses, decreased the production of profibrotic factors and directly prevented fibroblast activation. All these findings suggest a novel therapeutic role for RAASi in the treatment of renal fibrosis.

Topics: Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Animals; Cell Line; Connective Tissue Growth Factor; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Epithelial Cells; Eplerenone; Fibroblasts; Fibrosis; Humans; Kidney; Losartan; Male; Mannitol; Mineralocorticoid Receptor Antagonists; Proto-Oncogene Proteins c-sis; Ramipril; Rats, Wistar; Renin-Angiotensin System; Spironolactone

Anthracyclines such as doxorubicin are widely used in cancer therapy but their use is limited by cardiotoxicity. Up to date there is no established strategy for the prevention of anthracyclin-induced heart failure. In this study, we evaluated the role of the cardiac myocyte mineralocorticoid receptor (MR) during doxorubicin-induced cardiotoxicity.. A single high-dose or repetitive low-dose doxorubicin administration lead to markedly reduced left ventricular function in mice. Treatment with the MR antagonist eplerenone prevented doxorubicin-induced left ventricular dysfunction. In order to identify the cell types and molecular mechanisms involved in this beneficial effect we used a mouse model with cell type-specific MR deletion in cardiac myocytes. Cardiac myocyte MR deletion largely reproduced the effect of pharmacological MR inhibition on doxorubicin-induced cardiotoxicity. RNAseq from isolated cardiac myocytes revealed a repressive effect of doxorubicin on gene expression which was prevented by MR deletion.. We show here that (i) eplerenone prevents doxorubicin-induced left ventricular dysfunction in mice, and (ii) this beneficial effect is related to inhibition of MR in cardiac myocytes. Together with present clinical trial data our findings suggest that MR antagonism may be appropriate for the prevention of doxorubicin-induced cardiotoxicity.

Topics: Animals; Atrophy; Cardiotoxicity; Disease Models, Animal; Doxorubicin; Eplerenone; Female; Fibrosis; Mice, Inbred C57BL; Mice, Knockout; Mineralocorticoid Receptor Antagonists; Receptors, Mineralocorticoid; Ventricular Dysfunction, Left; Ventricular Function, Left; Ventricular Remodeling

Topics: Biomarkers; Collagen; Eplerenone; Fibrosis; Humans; Mineralocorticoid Receptor Antagonists; Randomized Controlled Trials as Topic; ST Elevation Myocardial Infarction

The unilateral ureteral obstruction (UUO) model not only induces renal interstitial fibrosis in the obstructed kidney but also induces injury in the contralateral kidney. We hypothesized that activation of the mineralocorticoid receptor (MR) may induce fibrosis in the early stage of UUO.. Thirty male Sprague-Dawley rats weighting 200 ± 10 g were used in this study and randomly divided into 3 groups: a UUO group, a UUO and eplerenone group, and a sham group. The contralateral kidney and plasma were harvested for further study 10 days after surgery.. The level of plasma aldosterone (869.95 ± 55.851 pg/mL) was significantly higher in the UUO group than that in the sham group (478.581 ± 36.186 pg/mL vs. UUO, p < 0.05). The infiltrated inflammatory cells (F4/80) and deposited collagens were increased significantly in the contralateral kidneys in the UUO group compared to those in the sham group, which were decreased by eplerenone. However, proliferating cell nuclear antigen was increased 2.47 times in the UUO group compared to the sham group in the contralateral kidney (p < 0.01), and those changes are attenuated by eplerenone. The expression of SGK-1 protein and mRNA was upregulated in the contralateral kidney in the UUO group, which is suppressed by eplerenone treatment. NF-κB pathway effecters were also changed markedly in the contralateral kidney in the UUO group and partly reversed by eplerenone.. Aldosterone induces inflammatory cell proliferation via the MR/SGK-1 and NF-κB pathways and eventually leads to fibrosis in the contralateral kidney.

Topics: Actins; Aldosterone; Animals; Cell Proliferation; Collagen; Eplerenone; Fibrosis; Immediate-Early Proteins; Kidney; Male; MAP Kinase Signaling System; Mineralocorticoid Receptor Antagonists; Proliferating Cell Nuclear Antigen; Protein Serine-Threonine Kinases; Rats; Rats, Sprague-Dawley; Receptors, Mineralocorticoid; Spironolactone; Tumor Necrosis Factor-alpha; Up-Regulation; Ureteral Obstruction

β-Adrenergic receptor (β-AR)-induction of collagen-I synthesis is partially mediated by the cardiac mineralocorticoid receptor (MR) system. However, it remains unclear whether the selective MR antagonist, eplerenone, inhibits collagen-I synthesis induced by β-AR stimulation. We investigated the effects of eplerenone on the responses to a non-selective β-AR agonist, isoproterenol, which induced collagen-I synthesis in primary cardiac fibroblasts (CFs) and the left ventricle. mRNAs encoding the MR and 11β-hydroxysteroid dehydrogenase type I (11β-HSD1) were evident in the left ventricle and primary CFs. mRNAs encoding the CYP family 11 subfamily B member 2 (CYP11-B2) were not detected, even after isoproterenol treatment. In vivo, isoproterenol induced collagenous fiber accumulation in the left ventricle. The phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), 11β-HSD1 levels, and mRNA/protein levels of collagen-I increased upon exposure to isoproterenol, but these increases were inhibited by eplerenone co-treatment. In primary CFs, isoproterenol increased the phosphorylation of ERK1/2 and the expression levels of both 11β-HSD1 and collagen-I; these isoproterenol-attributable effects were inhibited by co-treatment with eplerenone and PD98059, a specific inhibitor of mitogen-activated protein kinase/ERK kinase activity. The results suggest that 11β-HSD1 but not CYP11-B2 is expressed in primary CFs. Eplerenone inhibited isoproterenol-induced ERK1/2 phosphorylation and expression of 11β-HSD1 and collagen-I in primary CFs, as well as the progression of cardiac fibrosis in the left ventricle. Therefore, eplerenone inhibited the isoproterenol-induced increases in 11β-HSD1 and collagen-I expression in primary CFs, and progression of cardiac fibrosis in the left ventricle.

Topics: 11-beta-Hydroxysteroid Dehydrogenase Type 1; Adrenergic beta-Agonists; Animals; Cells, Cultured; Collagen Type I; Eplerenone; Fibroblasts; Fibrosis; Heart Ventricles; Isoproterenol; Male; Mineralocorticoid Receptor Antagonists; Rats; Rats, Inbred WKY; Spironolactone

The aldosterone inhibitor eplerenone (EPL) has been shown to reduce the incidence of atrial fibrillation (AF) in patients with systolic heart failure, but the mechanism is unknown.. This study hypothesized that by reducing atrial dilation and fibrosis in the absence of heart failure, EPL also reduces AF burden and prevents AF perpetuation.. The authors conducted a randomized controlled study in 34 sheep that were atrially tachypaced (13 ± 1 week). They compared daily oral EPL (n = 19) versus sugar pill (SP) treatment (n = 15) from the start of tachypacing. The endpoint was a continuous 7-day stretch of persistent AF (n = 29) or completion of 23 weeks tachypacing (n = 5).. EPL significantly reduced the rate of left atrial dilation increase during AF progression. Atria from EPL-treated sheep had less smooth muscle actin protein, collagen-III expression, interstitial atrial fibrosis, and cell hypertrophy than SP-treated sheep atria did. However, EPL did not modify the AF-induced increase in the rate of dominant frequency and ion channel densities seen under SP treatment, but rather prolonged the time to persistent AF in 26% of animals. It also reduced the degree of fibrillatory conduction, AF inducibility, and AF burden.. In the sheep model, EPL mitigates fibrosis and atrial dilation, modifies AF inducibility and AF complexity, and prolongs the transition to persistent AF in 26% of animals, but it does not prevent AF-induced electrical remodeling or AF persistence. The results highlight structural remodeling as a central upstream target to reduce AF burden, and the need to prevent electrical remodeling to avert AF perpetuation.

Topics: Animals; Atrial Fibrillation; Atrial Remodeling; Cardiac Pacing, Artificial; Eplerenone; Fibrosis; Male; Mineralocorticoid Receptor Antagonists; Sheep; Spironolactone

The purpose of the present study was to study the impacts of eplerenone (EPL), an antagonist of mineralocorticoid receptors (MR), on atrial fibrosis in a mouse model with selective fibrosis in the atrium, and to explore the possible mechanisms. Using mutant TGF-β1 transgenic (Tx) mice, we first demonstrated that EPL inhibited atrial fibrosis specifically and decreased macrophage accumulation in the atria of these mice. Results from immunohistochemistry and western blotting showed that EPL attenuated protein expression of fibrosis-related molecules such as connective tissue growth factor (CTGF) and fibronectin in the atria of Tx mice. In culture, EPL inhibited gene expression of fibrosis-related molecules such as fibronectin, α-SMA, and CTGF in TGF-β1-stimulated atrial fibroblasts. Finally, using a co-culture system, we showed that TGF-β1-stimulated atrial fibroblasts induced migration of macrophages and this was blocked by EPL. EPL also blocked TGF-β1-induced gene expression of intedeukin-6 (IL-6) in atrial fibroblasts. Therefore, we conclude that EPL attenuated atrial fibrosis and macrophage infiltration in Tx mice. TGF-β1 and IL-6 were involved in the impacts of EPL on activation of atrial fibroblasts and interactions between fibroblasts and macrophages.

Topics: Animals; Blotting, Western; Cells, Cultured; Coculture Techniques; Connective Tissue Growth Factor; Eplerenone; Fibroblasts; Fibronectins; Fibrosis; Gene Expression; Heart Atria; Interleukin-6; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Microscopy, Fluorescence; Mineralocorticoid Receptor Antagonists; Mutation; Myocardium; Reverse Transcriptase Polymerase Chain Reaction; Spironolactone; Transforming Growth Factor beta1

The transcription factor TBX1 plays an important role in the embryonic development of the heart. Nothing is known about its involvement in myocardial remodeling after acute myocardial infarction (AMI) and whether its expression can be modulated by a treatment with proven benefit such as mineralocorticoid receptor blockade.. Acute myocardial infarction was induced in 60 rats via left coronary artery ligation: 50 animals were randomized to be euthanized after 1, 2, 4, 12, or 24 weeks; 10 animals were treated with eplerenone (100 mg/kg/days) 7 days before the AMI until their euthanasia (4 weeks later); 8 additional animals underwent surgery without ligation (control). We analyzed the cardiac expression of TBX1, fetal genes, and fibrosis markers.. The gene and protein expression of TBX1 was increased in the infarcted myocardium, peaking 1 week after AMI (P < .01), without changes in the noninfarcted myocardium. Levels of the fetal genes and fibrosis markers also increased, peaking 4 weeks (P < .001) and 1 week (P < .01) after AMI, respectively. The TBX1 expression was correlated with that of the fibrosis markers (P < .01) but not the fetal genes. Eplerenone reduced the TBX1 increase and fibrosis induced by AMI, with an association improvement in ventricular function and remodeling in echocardiography.. These results show the reactivated expression of TBX1 and indicate its involvement in cardiac fibrosis and remodeling after AMI and its participation in the benefit from mineralocorticoid receptor blockade.

Topics: Actinin; Animals; Atrial Natriuretic Factor; Blotting, Western; Eplerenone; Fibrosis; Gene Expression Regulation, Developmental; Heart; Mineralocorticoid Receptor Antagonists; Myocardial Infarction; Myocardium; Myosin Heavy Chains; Natriuretic Peptide, Brain; Rats; Real-Time Polymerase Chain Reaction; RNA, Messenger; Spironolactone; T-Box Domain Proteins; Ventricular Remodeling

The fact that mineralocorticoid receptor antagonists reduce structural and functional alterations induced by cyclosporine A (CsA) indicates that aldosterone plays a key role in chronic CsA nephrotoxicity. We and other researchers have reported local renal aldosterone synthesis. To investigate local renal aldosterone's role in chronic CsA nephrotoxicity, we evaluated the effect of eplerenone (Epl) on renal structural damage and renal dysfunction in adrenalectomized (ADX) rats, and assessed whether the therapeutic benefit was associated with reduction of transforming growth factor-β1 (TGF-β1), connective tissue growth factor (CTGF), plasminogen activator inhibitor type 1 (PAI-1) and collagen I (COL-I) expression.. Male Sprague-Dawley rats fed a normal-sodium diet were divided in four groups: sham-ADX, ADX, CsA, or Epl. Rats in the ADX, CsA and Epl groups were adrenalectomized first. Aldosterone, sodium and potassium levels in serum and urine were measured on the second day. Two weeks later, vehicle (sham-ADX and ADX group), CsA (25mg/kg/d), or CsA and Epl (100 mg/ kg/d) combination was administrated, respectively. After six weeks, urinary protein, creatinine clearance (Ccr), tubulointerstitial fibrosis (TIF), aldosterone level in kidney, and renal aldosterone synthase CYP11B2, COL-I, TGF-β1, CTGF and PAI-1 gene expression levels were determined.. On the second day after surgery, adrenalectomized rats showed undetectable aldosterone with natriuresis, hyponatremia, decreased urinary potassium excretion and hyperpotassemia. CsA reduced Ccr, induced urinary proteins and up-regulated COL-I, TGF-β1, CTGF and PAI-1 gene expression with a significant development of TIF. Eplerenone administration prevented TIF and COL-I, TGF-β1 and PAI-1 up-regulation but did not improve renal function.. Our results suggest local renal aldosterone is an important mediator of renal injury induced by CsA.

Topics: Adrenalectomy; Aldosterone; Animals; Chronic Disease; Cyclosporine; Cytochrome P-450 CYP11B2; Disease Models, Animal; Electrolytes; Eplerenone; Fibrosis; Kidney; Kidney Diseases; Male; Potassium; Rats, Sprague-Dawley; RNA, Messenger; Sodium; Spironolactone

Mineralocorticoid receptor(MR) antagonism reduces sudden cardiac death in heart failure, but the underlying mechanism remains poorly understood. Concurrent treatment with an MR antagonist during rapid ventricular pacing (RVP) prevents development of adverse ventricular electrophysiological remodeling, interstitial fibrosis, inflammatory cytokine gene activation, and ventricular tachyarrhythmia inducibility without diminishing the extent of systolic dysfunction. We hypothesized that attenuating preexistent inflammatory pathways and myocardial fibrosis with eplerenone after systolic heart failure is established by rapid pacing can reduce electrical activation delays and arrhythmia vulnerability.. Dogs subjected to RVP for 8 weeks in the absence or presence of eplerenone treatment during the final 4 weeks of pacing were assessed by echocardiography, electrophysiology study,ventricular fibrosis measurements, and inflammatory cytokine mRNA expression analysis. Eplerenone reversed preexistent ventricular activation delays, interstitial fibrosis, inflammatory cytokine (interleukin-6, tumor necrosis factor-α) gene overexpression, and arrhythmia vulnerability in ventricular paced dogs with heart failure. Eplerenone failed to improve left ventricular systolic dysfunction or chamber enlargement. A correlation between severity of fibrosis and ventricular arrhythmia inducibility was found.. MR antagonism regresses rapid pacing-induced electrical delays, inflammatory cytokine gene activation, and fibrosis in heart failure. Ventricular arrhythmia vulnerability in heart failure is correlated with extent of fibrosis and electrical activation delays during premature excitation.

Topics: Action Potentials; Animals; Anti-Inflammatory Agents; Arrhythmias, Cardiac; Cardiac Pacing, Artificial; Cardiovascular Agents; Disease Models, Animal; Dogs; Eplerenone; Fibrosis; Heart Failure; Hypertrophy, Left Ventricular; Inflammation Mediators; Interleukin-6; Male; Mineralocorticoid Receptor Antagonists; Myocardium; Spironolactone; Time Factors; Tumor Necrosis Factor-alpha; Ventricular Dysfunction, Left; Ventricular Function, Left; Ventricular Remodeling

Chronic cyclosporine-(CsA)-mediated loss of kidney function is a major clinical problem in organ transplantation. We hypothesized that the mineralocorticoid receptor antagonist eplerenone (EPL) prevents chronic CsA-induced renal interstitial volume increase, tubule loss, and functional impairment in a rat model.. Sprague-Dawley rats received CsA alone (15 mg/kg/d p.o.), CsA and EPL (approximately 100 mg/kg/day p.o.) or vehicle (control) for 12 weeks. At 11 weeks, chronic indwelling arterial and venous catheters were implanted for continuous measurements of arterial blood pressure (BP) and GFR (inulin clearance) in conscious, freely moving animals. Plasma was sampled for analysis and kidney tissue was fixed for quantitative stereological analyses.. Compared to controls, CsA-treatment reduced relative tubular volume (0.73 ± 0.03 vs. 0.85 ± 0.01, p<0.05) and increased relative interstitial volume (0.080 ± 0.004 vs. 0.045 ± 0.003, p<0.05); EPL attenuated these changes (0.82 ± 0.02, p<0.05, and 0.060 ± 0.006, p<0.05, respectively). CsA-treated rats had more sclerotic glomeruli and a higher degree of vascular depositions in arterioles; both were significantly reduced in CsA+EPL-treated animals. CsA increased BP and reduced body weight gain and GFR. In CsA+EPL rats, weight gain, GFR and BP at rest (daytime) were normalized; however, BP during activity (night) remained elevated. Plasma sodium and potassium concentrations, kidney-to-body weight ratios and CsA whole blood concentration were similar in CsA and CsA+EPL rats.. It is concluded that in the chronic cyclosporine rat nephropathy model, EPL reduces renal tissue injury, hypofiltration, hypertension, and growth impairment. MR antagonists should be tested for their renoprotective potential in patients treated with calcineurin inhibitors.

Topics: Animals; Cyclosporine; Drug Interactions; Eplerenone; Fibrosis; Immunosuppressive Agents; Kidney; Longitudinal Studies; Male; Mineralocorticoid Receptor Antagonists; Nephritis, Interstitial; Rats; Rats, Sprague-Dawley; Spironolactone; Treatment Outcome

Cardiac steatosis and apoptosis are key processes in diabetic cardiomyopathy, but the underlying mechanisms have not been elucidated, leading to a lack of effective therapy. The mineralocorticoid receptor blocker, eplerenone, has demonstrated anti-fibrotic actions in the diabetic heart. However, its effects on the fatty-acid accumulation and apoptotic responses have not been revealed.. Non-hypertensive Zucker Diabetic Fatty (ZDF) rats received eplerenone (25 mg/kg) or vehicle. Zucker Lean (ZL) rats were used as control (n = 10, each group). After 16 weeks, cardiac structure and function was examined, and plasma and hearts were isolated for biochemical and histological approaches. Cultured cardiomyocytes were used for in vitro assays to determine the direct effects of eplerenone on high fatty acid and high glucose exposed cells.. In contrast to ZL, ZDF rats exhibited hyperglycemia, hyperlipidemia, insulin-resistance, cardiac steatosis and diastolic dysfunction. The ZDF myocardium also showed increased mitochondrial oxidation and apoptosis. Importantly, eplerenone mitigated these events without altering hyperglycemia. In cultured cardiomyocytes, high-concentrations of palmitate stimulated the fatty-acid uptake (in detriment of glucose assimilation), accumulation of lipid metabolites, mitochondrial dysfunction, and apoptosis. Interestingly, fatty-acid uptake, ceramides formation and apoptosis were also significantly ameliorated by eplerenone.. By blocking mineralocorticoid receptors, eplerenone may attenuate cardiac steatosis and apoptosis, and subsequent remodelling and diastolic dysfunction in obese/type-II diabetic rats.

Topics: Animals; Apoptosis; Cardiomegaly; Cell Line; Diabetes Mellitus, Type 2; Diabetic Cardiomyopathies; Diastole; Disease Models, Animal; Eplerenone; Fatty Acids; Fibrosis; Glucose; Hyperlipidemias; Lipid Metabolism; Male; Mineralocorticoid Receptor Antagonists; Mitochondria, Heart; Myocardium; Myocytes, Cardiac; Rats; Rats, Zucker; Spironolactone; Time Factors; Ventricular Dysfunction; Ventricular Function; Ventricular Remodeling

Prolonged elevation of serum aldosterone leads to renal fibrosis. Inflammation also plays a role in the pathogenesis of renal disease. We used a rat model of interstitial renal fibrosis to test the hypothesis that eplerenone-mediated aldosterone blockade prevents renal fibrosis due to its anti-inflammatory and anti-proliferative effects.. Eplerenone (a selective aldosterone blocker) or vehicle (control), was given to male Wistar rats (50 mg/kg, twice daily) for 7 days before unilateral ureteral obstruction (UUO) and for an additional 28 days after surgery. Body weight, blood pressure, renal histo-morphology, immune-staining for macrophages, monocyte chemotactic protein-1, proliferating cell nuclear antigen, α-smooth muscle actin, and serum and urine markers of renal function and oxidative stress were determined for both groups on 7, 14, and 28 days after surgery.. Epleronone had no effect on body weight or blood pressure. However, eplerenone inhibited the development of renal fibrosis, inflammation (macrophage and monocyte infiltration), interstitial cell proliferation, and activation of interstitial cells (α-SMA expression). Epleronone also reduced oxidative stress.. The anti-fibrotic effect of eplerenone appears to be unrelated to its effect on blood pressure. Eplerenone inhibits renal inflammation, interstitial cell proliferation, phenotypic changes of interstitial cells, and reduces oxidative stress.

Topics: Animals; Cell Proliferation; Disease Models, Animal; Eplerenone; Fibrosis; Inflammation; Male; Mineralocorticoid Receptor Antagonists; Nephritis, Interstitial; Oxidative Stress; Random Allocation; Rats; Rats, Wistar; Spironolactone

The renin-angiotensin-aldosterone system is involved in the arterial hypertension-associated cardiovascular remodeling. In this context, the development of cardiac fibrosis results from an imbalance between profibrotic and antifibrotic pathways, in which the role of aldosterone is yet not established. To determine the role of intracardiac aldosterone in the development of myocardial fibrosis during hypertension, we used a double transgenic model (AS-Ren) of cardiac hyperaldosteronism (AS) and systemic hypertension (Ren). The 9-month-old hypertensive mice had cardiac fibrosis, and hyperaldosteronism enhanced the fibrotic level. The mRNA levels of connective tissue growth factor and transforming growth factor-β1 were similarly increased in Ren and AS-Ren mice compared with wild-type and AS mice, respectively. Hyperaldosteronism combined with hypertension favored the macrophage infiltration (CD68(+) cells) in heart, and enhanced the mRNA level of monocyte chemoattractant protein 1, osteopontin, and galectin 3. Interestingly, in AS-Ren mice the hypertension-induced increase in bone morphogenetic protein 4 mRNA and protein levels was significantly inhibited, and B-type natriuretic peptide expression was blunted. The mineralocorticoid receptor antagonist eplerenone restored B-type natriuretic peptide and bone morphogenetic protein 4 levels and decreased CD68 and galectin 3 levels in AS-Ren mice. Finally, when hypertension was induced by angiotensin II infusion in wild-type and AS mice, the mRNA profiles did not differ from those observed in Ren and AS-Ren mice, respectively. The aldosterone-induced inhibition of B-type natriuretic peptide and bone morphogenetic protein 4 expression was confirmed in vitro in neonatal mouse cardiomyocytes. Altogether, we demonstrate that, at the cardiac level, hyperaldosteronism worsens hypertension-induced fibrosis through 2 mineralocorticoid receptor-dependent mechanisms, activation of inflammation/galectin 3-induced fibrosis and inhibition of antifibrotic factors (B-type natriuretic peptide and bone morphogenetic protein 4).

Topics: Aldosterone; Animals; Animals, Newborn; Antigens, CD; Antigens, Differentiation, Myelomonocytic; Blood Pressure; Blotting, Western; Bone Morphogenetic Protein 4; Cells, Cultured; Cytochrome P-450 CYP11B2; Eplerenone; Female; Fibrosis; Galectin 3; Gene Expression; Hyperaldosteronism; Hypertension; Male; Mice; Mice, Transgenic; Mineralocorticoid Receptor Antagonists; Myocardium; Natriuretic Peptide, Brain; Organ Size; Renin; Reverse Transcriptase Polymerase Chain Reaction; Spironolactone

Hypertension is well known to increase atrial fibrillation (AF) and the development of AF is associated with atrial chamber remodeling. Although mineralocorticoid receptor (MR) inhibition provides cardiovascular protection, the role of MR on atrial structural remodeling and inducibility of AF in hypertension remains unclear. Here, we investigated roles of the MR on atrial structural remodeling and inducibility of AF in hypertensive rats by using MR antagonist eplerenone (EPL). Dahl salt-sensitive (DS) rats were fed a normal-salt or a high-salt (HS) diet from 7 weeks, and a non-antihypertensive dose of EPL or vehicle was administrated from 13 weeks, at which time myocytes hypertrophy, interstitial fibrosis in the atrium and AF inducibility had increased, until 20 weeks. There was no significant difference in systolic blood pressure between DS+HS (186 ± 4 mm Hg) and DS+HS+EPL (184 ± 5 mm Hg) at 20 weeks. Burst atrial pacing demonstrated decreased AF inducibility in DS+HS+EPL (0 of 10) compared with DS+HS (7 of 10). Fibrosis and myocytes hypertrophy in the atrium were decreased in DS+HS+EPL with the reduction of atrial inflammatory cytokines. These beneficial effects of EPL were associated with less atrial oxidative stress, as assessed by 4-hydroxy-2-nonenal staining, and reduced activation of the Rho GTPase Rac1 in the atrium. Thus, MR has important roles in atrial structural remodeling and AF inducibility in Dahl rats. The effects of MR are associated, at least in part, with activation of Rac1-oxidative stress/inflammatory axis.

Topics: Animals; Atrial Fibrillation; Cardiomegaly; Eplerenone; Fibrosis; Heart Atria; Hypertension; Male; Mineralocorticoid Receptor Antagonists; Myocardium; Oxidative Stress; rac1 GTP-Binding Protein; Rats; Rats, Inbred Dahl; Receptors, Mineralocorticoid; Sodium Chloride, Dietary; Spironolactone

Osteopontin (OPN) has been implicated in the pathology of several renal conditions. Recently, we demonstrated in vitro that aldosterone has important roles in collagen synthesis by inducing OPN (Irita J, Okura T, Kurata M, Miyoshi K, Fukuoka T, Higaki J. Hypertension 51: 507-513, 2008). The aim of the present study was to clarify the roles of OPN in aldosterone-mediated renal fibrosis by infusing aldosterone into either wild-type (WT) or OPN knockout mice (OPN(-/-)). We used uninephrectomized mice treated with aldosterone and high salt to exacerbate renal fibrosis. After 4 wk of treatment with aldosterone, we showed similar increases in systolic blood pressure in both strains of mice. Urine albumin excretion was greater in aldosterone-infused WT mice than in aldosterone-infused OPN(-/-) mice. Immunohistochemical analysis showed high levels of OPN expression in aldosterone-infused WT mice. Interstitial fibrosis and inflammatory infiltrations were increased in aldosterone-infused WT mice compared with either vehicle-infused WT or aldosterone-infused OPN(-/-) mice. These changes were ameliorated markedly by eplerenone treatment in aldosterone-infused WT mice. Aldosterone-infused WT mice also had increased expression of NADPH oxidase subunits compared with aldosterone-infused OPN(-/-) mice. We observed a marked increase in oxidative stress markers in aldosterone-infused WT mice compared with aldosterone-infused OPN(-/-) mice. These results indicate that OPN is a promoter of aldosterone-induced inflammation, oxidative stress, and interstitial fibrosis in the kidney and suggest that inhibition of OPN may be a potential therapeutic target for prevention of renal injury.

Topics: Albuminuria; Aldosterone; Animals; Blood Pressure; Eplerenone; Fibrosis; Inflammation; Kidney; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Mineralocorticoid Receptor Antagonists; Osteopontin; Oxidative Stress; Sodium Chloride, Dietary; Spironolactone

Large clinical trials have shown that mineralocorticoid receptor (MR) antagonists improve cardiovascular or total mortality in patients with heart failure or myocardial infarction even though the patients were taking angiotensin-converting enzyme inhibitors or angiotensin II receptor (AT1R) antagonists. We previously reported that cardiac fibrosis induced by aldosterone and salt (Ald-NaCl) was exaggerated in AT1aR knockout mice (AT1aR-KOs). As the association of Rho kinase and oxidative stress was reported in Ald-NaCl-induced hypertension of rats, we investigated the effects of an MR antagonist (eplerenone) and a Rho kinase inhibitor (fasudil) on Ald-NaCl-induced cardiac fibrosis in AT1aR-KOs. AT1aR-KOs were administered aldosterone (0.15 microg/h) subcutaneously using an osmotic minipump and were provided with 1% NaCl drinking water for 4weeks. AT1aR-KOs receiving Ald-NaCl were treated with a low (30 mg/kg/day) or high (100mg/kg/day) dose of eplerenone or a fasudil (100mg/kg/day). Systolic blood pressure (SBP), left ventricular weight/body weight (LVW/BW), histological examination and cardiac gene expression were evaluated on day 28. Ald-NaCl treatment caused increases in SBP and LVW/BW in AT1aR-KOs, and eplerenone dose-dependently decreased SBP, LVW/BW and cardiac fibrosis. Fasudil decreased LVW/BW and cardiac fibrosis without affecting SBP. The expressions of connecting tissue growth factor (CTGF) and nicotinamide adenine dinucleotide phosphate (NADPH) components (p22phox, p47phox and p67phox) were increased in Ald-NaCl-treated AT1aR-KOs, and eplerenone or fasudil decreased the expression of CTGF and NADPH components. Phosphorylated ERM (a marker of the phosphorylation of Rho kinase) was increased in Ald-NaCl-treated AT1aR-KOs and was decreased by eplerenone. Nitrotyrosine and 4-hydroxy-2-nonenal, which indicate tissue damage via oxidative stress, were increased in AT1aR-KO and were apparently attenuated by eplerenone or fasudil. These results suggested that the Rho kinase pathway was activated to induce cardiac fibrosis by Ald-NaCl via MR in AT1aR-KOs. A Rho kinase inhibitor as well as eplerenone might be useful for cardiac damage by Ald-NaCl.

Topics: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; Aldosterone; Animals; Blood Pressure; Eplerenone; Fibrosis; Heart; Immunohistochemistry; Mice; Mice, Knockout; Mineralocorticoid Receptor Antagonists; Myocardium; Oxidative Stress; Receptor, Angiotensin, Type 1; Reverse Transcriptase Polymerase Chain Reaction; rho-Associated Kinases; Sodium Chloride; Spironolactone

Myocardial fibrosis increases arrhythmia vulnerability of the diseased heart. The renin-angiotensin-aldosterone system (RAAS) governs myocardial collagen synthesis. We hypothesized that reducing cardiac fibrosis by chronic RAAS inhibition would result in reduced arrhythmia vulnerability of the senescent mouse heart. Wild-type mice (52 wk old) were treated for 36 wk: 1) untreated control (C); 2) eplerenone (E); 3) losartan (L); and 4) cotreatment with eplerenone and losartan (EL). Ventricular epicardial activation mapping was performed on Langendorff-perfused hearts. Arrhythmia inducibility was tested by one to three premature stimuli and burst pacing. Longitudinal and transverse conduction velocity and dispersion of conduction were determined during pacing at a basic cycle length of 150 ms. Sirius red staining (collagen) was performed. As a result, in the RV of mice in the E, L, and EL groups, transverse conduction velocity was significantly increased and anisotropic ratio was significantly decreased compared with those values of mice in the C group. Anisotropic reentrant arrhythmias were induced in 52% of untreated mice and significantly reduced to 22%, 26%, and 16% in the E, L, and EL groups, respectively. Interstitial fibrosis was significantly decreased in both the RV and LV of all treated groups. Scattered patches of replacement fibrosis were found in 90% of untreated hearts, which were significantly reduced in the E, L, and EL groups. A strong correlation between the abundance of patchy fibrosis and arrhythmia inducibility was found. In conclusion, chronic RAAS inhibition limited aging-related interstitial fibrosis. The lower arrhythmogeneity of treated mice was directly correlated to the reduced amount of patchy fibrosis.

Topics: Age Factors; Aging; Angiotensin II Type 1 Receptor Blockers; Animals; Arrhythmias, Cardiac; Blood Pressure; Cardiac Pacing, Artificial; Cell Communication; Cellular Senescence; Connexin 43; Disease Models, Animal; Echocardiography, Doppler; Electrocardiography; Epicardial Mapping; Eplerenone; Female; Fibrosis; Heart Conduction System; Heart Diseases; Losartan; Mice; Mice, Inbred C57BL; Mineralocorticoid Receptor Antagonists; Myocardium; Renin-Angiotensin System; Spironolactone; Ventricular Function, Left; Ventricular Function, Right

We hypothesized that combination treatment with the mineralocorticoid receptor antagonist eplerenone and the calcium channel blocker amlodipine elicits better renoprotective effects than monotherapy with either drug, via different mechanisms in Dahl salt-sensitive (DS) hypertensive rats. DS rats were fed a high-salt diet (4% NaCl) for 10 wk and were treated with vehicle (n = 12), eplerenone (50 mg x kg(-1) x day(-1), p.o., n = 12), amlodipine (3 mg x kg(-1) x day(-1), p.o., n = 12), or eplerenone plus amlodipine (n = 12) after 2 wk of salt feeding. Vehicle-treated DS rats developed proteinuria, which was attenuated by eplerenone or amlodipine. Interestingly, eplerenone attenuated the glomerulosclerosis and podocyte injury, but amlodipine did not. Conversely, treatment with amlodipine markedly improved interstitial fibrosis, while the effect of eplerenone was minimal. Combination treatment markedly improved proteinuria, glomerulosclerosis, podocyte injury, and interstitial fibrosis in DS rats. Renal hypoxia estimated by pimonidazole, vascular endothelial growth factor expression, and density of peritubular endothelial cells was exacerbated by salt feeding. Amlodipine, either as monotherapy or in combination, ameliorated the renal hypoxia, whereas eplerenone treatment had no effect. In conclusion, both eplerenone and amlodipine attenuated renal injuries in high salt-fed DS rats, but the targets for renoprotection differed between these two drugs, with eplerenone predominantly acting on glomeruli and amlodipine acting on interstitium. The combination of eplerenone and amlodipine improved renal injury more effectively than either monotherapy in high salt-fed DS rats, presumably by achieving their own renoprotective effects.

Topics: Amlodipine; Animals; Antihypertensive Agents; Blood Pressure; Calcium Channel Blockers; Cell Hypoxia; Creatinine; Drug Therapy, Combination; Endothelial Cells; Eplerenone; Fibrosis; Hypertension; Immediate-Early Proteins; Kidney Diseases; Kidney Glomerulus; Kidney Tubules; Male; Mineralocorticoid Receptor Antagonists; Podocytes; Protein Serine-Threonine Kinases; Proteinuria; Rats; Rats, Inbred Dahl; Receptors, Mineralocorticoid; Sodium Chloride, Dietary; Spironolactone; Time Factors; Vascular Endothelial Growth Factor A

Aldosterone receptor antagonism reduces mortality and improves post-myocardial infarction (MI) remodeling. Because aldosterone and estrogen signaling pathways interact, we hypothesized that aldosterone blockade is sex-specific. Therefore, we investigated the impact of eplerenone on left ventricular (LV) remodeling and gene expression of male infarcted rats versus female infarcted rats. MI and Sham animals were randomized to receive eplerenone (100 mg/kg/day) or placebo 3 days post-surgery for 4 weeks and assessed by echocardiography. In the MI placebo group, left ventricular end-diastolic dimension (LVEDD) increased from 7.3 +/- 0.4 mm to 10.2 +/- 1.0 mm (p < 0.05) and ejection fraction (EF) decreased from 82.3 +/- 4% to 45.5 +/- 11% (p < 0.05) in both sexes (p = NS between groups). Eplerenone attenuated LVEDD enlargement more effectively in females (8.8 +/- 0.2 mm, p < 0.05 vs. placebo) than in males (9.7 +/- 0.2 mm, p = NS vs. placebo) and improved EF in females (56.7 +/- 3%, p < 0.05 vs. placebo) but not in males (50.6 +/- 3%, p = NS vs. placebo). Transcriptomic analysis using Rat_230-2.0 microarrays (Affymetrix) revealed that in females 19% of downregulated genes and 44% of upregulated genes post-MI were restored to normal by eplerenone. In contrast, eplerenone only restored 4% of overexpressed genes in males. Together, these data suggest that aldosterone blockade reduces MI-induced cardiac remodeling and phenotypic alterations of gene expression preferentially in females than in males. The use of transcriptomic signatures to detect greater benefit of eplerenone in females has potential implications for personalized medicine.

Topics: Animals; Cluster Analysis; Eplerenone; Female; Fibrosis; Gene Expression Profiling; Gene Expression Regulation; Male; Mineralocorticoid Receptor Antagonists; Myocardial Infarction; Placebos; Rats; Rats, Wistar; Sex Characteristics; Spironolactone; Ventricular Remodeling

Aldosterone has been implicated as one of the mediators of cardiovascular injury in various diseases. This study examines whether mineralocorticoid antagonism ameliorates or prevents the adverse cardiac effects of hypertension and aging. Male 22-wk-old spontaneously hypertensive rats (SHR) were divided into two groups, 15 rats in each. One group received no treatment; the other was given eplerenone ( approximately 100 mg.kg(-1).day(-1)). At the age of 54 wk, indexes of cardiovascular mass, systemic and regional hemodynamics, including coronary, left ventricular function, and myocardial collagen content, were determined in all rats. Hemodynamic studies were done in conscious rats. Arterial pressure was lowered only slightly in eplerenone-treated rats, and cardiac output and total peripheral resistance did not differ from control rats. Left and right ventricular and aortic mass indexes were unaffected by eplerenone; however, concentration of hydroxyproline in the right and left ventricle was decreased significantly (P < 0.05) by eplerenone. This was accompanied by an improvement in left ventricular diastolic function and coronary hemodynamics. In conclusion, long-term therapy with the mineralocorticoid receptor antagonist eplerenone ameliorated adverse cardiac effects of both hypertension and aging in SHR. Thus reduction in myocardial fibrosis, paralleled by improvements in left ventricular function and coronary hemodynamics, was observed in eplerenone-treated SHR.

Topics: Animals; Blood Pressure; Coronary Circulation; Eplerenone; Fibrosis; Hypertension; Male; Mineralocorticoid Receptor Antagonists; Myocardium; Rats; Rats, Inbred SHR; Spironolactone; Time Factors; Treatment Outcome; Ventricular Dysfunction, Left; Ventricular Function, Left

Tenascin-C is an extracellular matrix glycoprotein that is supposed to be a profibrotic molecule in various fibrogenic processes. To elucidate its significance for myocardial fibrosis in the hypertensive heart, we used a mouse model with infusion of angiotensin II and examined results by histology, immunohistochemistry, in situ hybridization, and quantitative real-time reverse transcriptase polymerase chain reaction (RT-PCR). Angiotensin II treatment elevated blood pressure and expression of tenascin-C by interstitial fibroblasts in perivascular fibrotic lesions, and angiotensin II infusion caused accumulation of macrophages. It also upregulated expression of collagen Ialpha2; IIIalpha1; and proinflammatory/profibrotic mediators including transforming growth factor beta (TGFbeta), platelet-derived growth factor alpha (PDGF-A), PDGF-B, and PDGF-receptor alpha, but not IL-1beta and PDGF-receptor beta, in the myocardium. Treatment with an aldosterone receptor antagonist, eplerenone, significantly attenuated angiotensin II-induced fibrosis, expression of tenascin-C, and inflammatory changes without affecting the blood pressure level. In vitro, neither eplerenone nor aldosterone exerted any influence on tenascin-C expression of cardiac fibroblasts, whereas angiotensin II, TGF-beta1, and PDGF significantly upregulated expression of tenascin-C. These results suggest that, in the angiotensin II-induced hypertensive mouse heart: (1) tenascin-C may be involved in the progression of cardiac fibrosis and (2) aldosterone may elicit inflammatory reactions in myocardium, which might, in turn, induce tenascin-C synthesis of fibroblasts through at least 2 pathways mediated by TGF-beta and PDGF-A-B/PDGF-receptor alpha.

Topics: Aldosterone; Analysis of Variance; Angiotensin II; Animals; Blood Pressure; Body Weight; Cytokines; Disease Models, Animal; Eplerenone; Female; Fibroblasts; Fibrosis; Hypertension; Immunohistochemistry; In Situ Hybridization; Inflammation Mediators; Intercellular Signaling Peptides and Proteins; Macrophages; Mice; Mice, Inbred BALB C; Mineralocorticoid Receptor Antagonists; Myocardium; Reverse Transcriptase Polymerase Chain Reaction; Spironolactone; Tenascin; Up-Regulation; Vasoconstrictor Agents

Mineralocorticoid receptor (MR) antagonism reverses established inflammation, oxidative stress, and cardiac fibrosis in the mineralocorticoid/salt-treated rat, whereas withdrawal of the mineralocorticoid deoxycorticosterone (DOC) alone does not. Glucocorticoid receptors (GRs) play a central role in regulating inflammatory responses but are also involved in cardiovascular homeostasis. Physiological glucocorticoids bind MR with high affinity, equivalent to that for aldosterone, but are normally prevented from activating MR by pre-receptor metabolism by 11beta-hydroxysteroid dehydrogenase 2. We have previously shown a continuing fibrotic and hypertrophic effect after DOC withdrawal, putatively mediated by activation of glucocorticoid/MR complexes; the present study investigates whether this effect is moderated by antiinflammatory effects mediated via GR. Uninephrectomized rats, drinking 0.9% saline solution, were treated as follows: control; DOC (20 mg/wk) for 4 wk; DOC for 4 wk and no steroid wk 5-8; DOC for 4 wk plus the MR antagonist eplerenone (50 mg/kg.d) wk 5-8; DOC for 4 wk plus the GR antagonist RU486 (2 mg/d) wk 5-8; and DOC for 4 wk plus RU486 and eplerenone for wk 5-8. After steroid withdrawal, mineralocorticoid/salt-induced cardiac hypertrophy is sustained, but not hypertension. Inflammation and fibrosis persist after DOC withdrawal, and GR blockade with RU486 has no effect on these responses. Rats receiving RU486 for wk 5-8 after DOC withdrawal showed marginal blood pressure elevation, whereas eplerenone alone or coadministered with RU486 reversed all DOC/salt-induced circulatory and cardiac pathology. Thus, sustained responses after mineralocorticoid withdrawal appear to be independent of GR signaling, in that blockade of endogenous antiinflammatory effects via GR does not lead to an increase in the severity of responses in the mineralocorticoid/salt-treated rat after steroid withdrawal.

Topics: Animals; Biomarkers; Blood Pressure; Cardiomegaly; Cardiomyopathies; Coronary Vessels; Desoxycorticosterone; Drug Administration Schedule; Eplerenone; Fibrosis; Hormone Antagonists; Male; Mifepristone; Myocardium; Organ Size; Oxidative Stress; Rats; Rats, Sprague-Dawley; Receptors, Glucocorticoid; Signal Transduction; Sodium Chloride; Spironolactone; Vasculitis

We previously reported that a high-sodium diet activates the local renin-angiotensin-aldosterone system (RAAS) in cardiovascular tissues of Dahl salt-sensitive hypertensive (DS) rats. Angiotensin-converting enzyme 2 (ACE2) is a novel regulator of blood pressure (BP) and cardiac function. The effect of blockade of aldosterone or angiotensin II (Ang II) on cardiac angiotensinogen and ACE2 in DS rats is unknown.. The BP, plasma renin activity (PRA), plasma aldosterone concentration (PAC), heart weight, endothelium-dependent relaxation (EDR), and messenger RNA (mRNA) levels of collagen III, angiotensinogen, ACE, and ACE2 in the heart were measured in DS rats and in Dahl salt-resistant (DR) rats fed high or low salt diets. The rats were treated orally with or without eplerenone (100 mg/kg/d), candesartan (10 mg/kg/d), or both drugs combined for 8 weeks.. A high salt diet increased BP (140%), heart/body weight (132%), and collagen III mRNA levels (146%) and decreased PRA and PAC concomitant with increased expression of cardiac angiotensinogen mRNA and decreased mRNA levels of ACE2 in DS rats. Eplerenone or candesartan significantly decreased the systolic BP from 240 +/- 5 mm Hg to 164 +/- 4 mm Hg or to 172 +/- 10 mm Hg, respectively (P < .05). Eplerenone or candesartan partially improved heart/body weight and cardiac fibrosis, improved EDR and decreased cardiac ACE and angiotensinogen mRNA levels in DS rats. Candesartan increased ACE2 mRNA levels in the heart. Combination therapy normalized BP and further improved cardiac hypertrophy, fibrosis, and EDR.. In DS rats, blockade of aldosterone or Ang II protects cardiac hypertrophy and fibrosis by inactivation of the local RAAS in the heart.

Topics: Aldosterone; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme 2; Angiotensinogen; Animals; Benzimidazoles; Biphenyl Compounds; Cardiomegaly; Endothelium, Vascular; Eplerenone; Fibrosis; Hypertension; Male; Mineralocorticoid Receptor Antagonists; Myocardium; Peptidyl-Dipeptidase A; Rats; Rats, Inbred Dahl; Receptor, Angiotensin, Type 1; Renin-Angiotensin System; RNA, Messenger; Spironolactone; Tetrazoles

Enhanced extracellular matrix accumulation rather than cell proliferation contributes to later stages of in-stent restenosis. Aldosterone itself has been shown to increase cardiovascular fibrosis, therefore, we studied the suppressive effects of eplerenone, a new aldosterone receptor antagonist, on neointimal hyperplasia after coronary stent implantation in swine.. Palmatz-Shatz stents were implanted in the left anterior descending artery of 36 pigs. One hundred milligrams of Eplerenone was orally administered from 1 week before, to 4 weeks after stent implantation in Group E (n=18), and vehicle was given to Group C (n=18). Pigs were sacrificed 1 or 4 weeks after stent implantation. The number of infiltrating macrophages was calculated at 1 week. Morphometrical analysis was performed to measure the area of each layer, and %area of fibrosis and mRNA for collagen I, III and TGF-beta was analyzed by RT-PCR at 4 weeks.. The number of infiltrating macrophages was less in Group E than in Group C (p<0.01). The overall size of coronary arteries at 4 weeks was similar in both groups. However, the luminal area was larger in Group E than in Group C (p<0.05), and the intimal area was smaller in Group E than in Group C (p<0.05). The %area of fibrosis was significantly less in Group E than in Group C at 4 weeks (p<0.01). In Group E, the expression of mRNA for collagen I, III and TGF-beta was significantly reduced.. Orally administered eplerenone attenuated collagen accumulation within the neointima, thereby inhibiting neointimal hyperplasia after stent implantation.

Topics: Actins; Administration, Oral; Animals; Blood Vessel Prosthesis Implantation; Collagen Type I; Collagen Type III; Coronary Restenosis; Coronary Vessels; Disease Models, Animal; Eplerenone; Fibrosis; Hyperplasia; Immunohistochemistry; Macrophages; Male; Mineralocorticoid Receptor Antagonists; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Spironolactone; Stents; Swine; Time Factors; Transforming Growth Factor beta; Tunica Intima

Recent clinical studies implicate proteinuria as a key prognostic factor for renal and cardiovascular complications in hypertensives. The pathogenesis of proteinuria in hypertension is, however, poorly elucidated. Podocytes constitute the final filtration barrier in the glomerulus, and their dysfunction may play a pivotal role in proteinuria. In the present study, we examined the involvement of podocyte injury in Dahl salt-hypertensive rats, an animal model prone to hypertensive glomerulosclerosis, and explored the effects of inhibition of aldosterone. Four-week-old Dahl salt-resistant and salt-sensitive rats were fed a 0.3% or 8.0% NaCl diet. Some salt-loaded Dahl salt-sensitive rats were treated with a selective aldosterone blocker eplerenone (1.25 mg/g diet) or hydralazine (0.5 mmol/L). After 6 weeks, salt-loaded Dahl salt-sensitive rats developed severe hypertension, proteinuria, and glomerulosclerosis. Immunostaining for nephrin, a constituent of slit diaphragm, was attenuated, whereas expressions of damaged podocyte markers desmin and B7-1 were upregulated in the glomeruli of salt-loaded Dahl salt-sensitive rats. Electron microscopic analysis revealed podocyte foot process effacement. Podocytes were already impaired at as early as 2 weeks of salt loading in Dahl salt-sensitive rats, when proteinuria was modestly increased. Both eplerenone and hydralazine partially reduced systemic blood pressure as measured by indirect and direct methods in salt-loaded Dahl salt-sensitive rats, but only eplerenone dramatically improved podocyte damage and retarded the progression of proteinuria and glomerulosclerosis. Our findings suggest that podocyte injury underlies the glomerulopathy of Dahl salt-hypertensive rats and that inhibition of aldosterone by eplerenone is protective against podocyte damage, proteinuria, and glomerulosclerosis in this hypertensive model.

Topics: Animals; Apoptosis; Biomarkers; Blood Pressure; Eplerenone; Fibrosis; Glomerulosclerosis, Focal Segmental; Hydralazine; Hypertension; Kidney; Male; Microscopy, Electron; Mineralocorticoid Receptor Antagonists; Nephritis; Oxidative Stress; Podocytes; Proteinuria; Rats; Rats, Inbred Dahl; Spironolactone; Time Factors

Aldosterone promotes cardiovascular inflammation and remodeling, both of which are characteristic changes in hypertensive and failing hearts. Since chronic inhibition of nitric oxide (NO) synthase with N(omega)-nitro-L-arginine methyl ester (L-NAME) induces systemic hypertension associated with cardiovascular inflammation and remodeling, we examined the potential role of aldosterone in this process using eplerenone, a selective aldosterone receptor antagonist. Ten-week-old male Wistar-Kyoto rats were randomly divided into 3 groups: the control group (no treatment), the L-NAME group (received L-NAME 1 g/L in drinking water), and the L-NAME+Eplerenone group (L-NAME plus eplerenone at 100 mg/kg/day). After 8 weeks of the treatment, the L-NAME group showed significantly higher systolic blood pressure than the control group (198 +/- 7 vs. 141 +/- 3 mmHg, P < 0.05). Eplerenone did not affect the increase in blood pressure caused by L-NAME (189 +/- 12 mmHg). Chronic inhibition of NO synthesis increased the plasma aldosterone concentration and CYP11B2 mRNA in adrenal glands. Cardiac inflammation and fibrosis were detected in the L-NAME group, while both changes were completely prevented by eplerenone. Cardiac hypertrophy was induced in L-NAME group, but was partially prevented by eplerenone. In the L-NAME group, left ventricular fractional shortening (LVFS: 27 +/- 2 vs. 38 +/- 1%) and E/A ratio (1.7 +/- 0.1 vs. 2.1 +/- 0.1) were significantly lower and LV end-diastolic pressure (LVEDP) was higher (4.9 +/- 0.6 vs. 13.9 +/- 0.5 mmHg) without LV enlargement, compared with those in the control group (P < 0.05). Eplerenone completely normalized LVFS (36 +/- 2%), E/A ratio (2.2 +/- 0.1), and LVEDP (6.2 +/- 0.7 mmHg). These results suggest that chronic inhibition of NO synthesis induces cardiac inflammation and dysfunction via an aldosterone receptor-dependent mechanism.

Topics: Actins; Aldosterone; Animals; Blotting, Western; Cytochrome P-450 CYP11B2; Drug Therapy, Combination; Eplerenone; Fibrosis; Heart Failure; Heart Ventricles; Hypertension; Immunohistochemistry; Male; Mineralocorticoid Receptor Antagonists; NF-kappa B; NG-Nitroarginine Methyl Ester; Nitric Oxide; Peptide Fragments; Proliferating Cell Nuclear Antigen; Protein Precursors; Random Allocation; Rats; Rats, Inbred WKY; Receptors, Mineralocorticoid; RNA, Messenger; Spironolactone; Transforming Growth Factor beta; Transforming Growth Factor beta1

Previous experiments have studied separately the development of either cardiac or aortic fibrosis and stiffness in aldosterone (Aldo)-salt hypertensive rats. Our aim was to determine in vivo the effects of Aldo and the Aldo receptor antagonist eplerenone (Epl) on simultaneous changes in cardiac and arterial structure and function and their interactions.. Aldo was administered in uninephrectomised Sprague-Dawley rats receiving a high-salt diet from 8 to 12 weeks of age. Three groups of Aldo-salt rats were treated with 1 to 100 mg/kg-1. d-1 Epl by gavage. Arterial elasticity was measured by elastic modulus (Einc)-wall stress curves using medial cross-sectional area (MCSA). The cardiac and arterial walls were analysed by histomorphometry (elastin and collagen), immunohistochemistry (EIIIA fibronectin, Fn), and Northern blot (collagens I and III). Aldo caused increased systolic blood pressure (SBP), carotid Einc, MCSA, and EIIIA Fn with no change in wall stress or elastin and collagen densities. No difference in collagen mRNA levels was detected between groups. During the same period, cardiac mass and collagen mRNA and protein levels increased markedly in the myocardial tissue. Epl normalised collagen in the myocardium, Eincwall stress curves, MCSA, and EIIIA Fn in Aldo rats. These dose-dependent effects were not accompanied by a consistent reduction in SBP and cardiac mass.. In exogenous hyperaldosteronism in the rat, Aldo causes independently myocardial collagen and arterial Fn accumulation, the latter being responsible for increased intrinsic carotid stiffness. Epl prevents both cardiac and arterial effects but does not reduce consistently SBP.

Topics: Animals; Aorta; Blood Pressure; Blotting, Northern; Carotid Artery Diseases; Collagen; Eplerenone; Fibrosis; Heart Diseases; Hypertension; Immunohistochemistry; Male; Mineralocorticoid Receptor Antagonists; Myocardium; Rats; Rats, Sprague-Dawley; RNA, Messenger; Spironolactone; Structure-Activity Relationship; Vascular Diseases

Eplerenone, a selective aldosterone blocker, has been shown to attenuate cardiac fibrosis and decrease cardiovascular events in both experimental and clinical studies. We examined the cardioprotective effect of eplerenone in myocardial infarction (MI) rats receiving different levels of salt in their diet. The MI rats were randomly divided into five groups: Group CL, animals received a low-salt diet (0.015%); Group EpL, a low-salt diet with eplerenone (100 mg/kg/day in food); Group CH, a high-salt diet (0.9%); Group EpH, a high-salt diet with eplerenone; and Group C, a normal salt diet (0.3%). These diets were continued for 4 weeks. Echocardiographic and histomorphological examinations revealed that the administration of eplerenone significantly improved the cardiac function, significantly suppressed compensatory cardiac hypertrophy and significantly reduced cardiac fibrosis in both the interstitial and the perivascular areas in the high-salt diet group (Group EpH). However, eplerenone had no observable effects in the low-salt diet group (Group EpL). Also, these examinations demonstrated that the left ventricular remodeling after MI was suppressed and the cardiac function was improved in the group receiving a low-salt diet without eplerenone (Group CL), even though there was a significant increase of aldosterone level in blood, in comparison to the group receiving a high-salt diet without eplerenone (Group CH). These results indicate that the cardioprotective effect of eplerenone varies depending on the salt intake.

Topics: Aldosterone; Animals; Cardiomegaly; Diet, Sodium-Restricted; Echocardiography; Eplerenone; Fibrosis; Food-Drug Interactions; Heart; Male; Mineralocorticoid Receptor Antagonists; Myocardial Infarction; Rats; Rats, Wistar; Sodium Chloride; Spironolactone; Ventricular Remodeling

Aldosterone blockade reduces morbidity and mortality in patients with heart failure. We studied the effects of eplerenone, a novel aldosterone blocker, on the progression of left ventricular dysfunction and remodeling in rats with dilated cardiomyopathy after autoimmune myocarditis. Twenty-eight days after immunization, the surviving Lewis rats were randomized to 1 month's oral treatment with low-dose eplerenone (group L), high-dose eplerenone (group H) or vehicle (group V). Five of 15 (33%) rats in group V and 3 of 15 (20%) rats in group L died during the course of treatment. High-dose eplerenone significantly reduced cardiomyocyte hypertrophy, heart weight and heart weight to body weight ratio. Eplerenone improved left ventricular function in a dose-dependent manner. Central venous pressure and left ventricular end-diastolic pressure were lower, and +/-dP/dt and fractional shortening were higher in group H than group V. Eplerenone also attenuated myocardial fibrosis and reduced left ventricular mRNA expressions of TGF-beta(1) and collagen-III. Our results indicate that treatment with eplerenone improved left ventricular dysfunction and attenuated left ventricular remodeling in rats with heart failure.

Topics: Animals; Autoimmune Diseases; Cardiomyopathy, Dilated; Collagen Type III; Dose-Response Relationship, Drug; Electrocardiography; Eplerenone; Fibrosis; Hemodynamics; Male; Mineralocorticoid Receptor Antagonists; Myocarditis; Myocardium; Rats; Rats, Inbred Lew; RNA, Messenger; Spironolactone; Transforming Growth Factor beta; Ventricular Dysfunction, Left; Ventricular Remodeling

Although aldosterone, acting via mineralocorticoid receptors, causes left ventricular (LV) hypertrophy in experimental models of high-aldosterone hypertension, little is known about the role of aldosterone or mineralocorticoid receptors in mediating adverse remodeling in response to chronic pressure overload.. We used the mineralocorticoid receptor-selective antagonist eplerenone (EPL) to test the role of mineralocorticoid receptors in mediating the transition from hypertrophy to failure in mice with chronic pressure overload caused by ascending aortic constriction (AAC). One week after AAC, mice were randomized to regular chow or chow containing EPL (200 mg/kg per day) for an additional 7 weeks. EPL had no significant effect on systolic blood pressure after AAC. Eight weeks after AAC, EPL treatment improved survival (94% versus 65%), attenuated the increases in LV end-diastolic (3.4+/-0.1 versus 3.7+/-0.1 mm) and end-systolic (2.0+/-0.1 versus 2.5+/-0.2 mm) dimensions, and ameliorated the decrease in fractional shortening (42+/-2% versus 34+/-4%). EPL also decreased myocardial fibrosis, myocyte apoptosis, and the ratio of matrix metalloproteinase-2/tissue inhibitor of matrix metalloproteinase-2. These beneficial effects of EPL were associated with less myocardial oxidative stress, as assessed by 3-nitrotyrosine staining, reduced expression of the adhesion molecule intercellular adhesion molecule-1, and reduced infiltration by macrophages.. Mineralocorticoid receptors play an important role in mediating the transition from LV hypertrophy to failure with chronic pressure overload. The effects of mineralocorticoid receptor stimulation are associated with alterations in the interstitial matrix and myocyte apoptosis and may be mediated, at least in part, by oxidative stress and inflammation.

Topics: Animals; Aorta; Apoptosis; Blood Pressure; Cell Size; Chronic Disease; Constriction, Pathologic; Drug Evaluation, Preclinical; Eplerenone; Fibrosis; Heart Failure; Hypertrophy, Left Ventricular; Intercellular Adhesion Molecule-1; Ligation; Male; Matrix Metalloproteinases; Mice; Mineralocorticoid Receptor Antagonists; Myocarditis; Myocardium; Myocytes, Cardiac; Oxidative Stress; Pressure; Random Allocation; Receptors, Mineralocorticoid; Spironolactone; Tissue Inhibitor of Metalloproteinase-1; Tissue Inhibitor of Metalloproteinase-2; Tyrosine

Aldosterone has been thought to act primarily on epithelia to regulate fluid and electrolyte homeostasis. Mineralocorticoid receptors (MR), however, are also expressed in nonepithelial tissues, such as the heart and vascular smooth muscle. Recently, pathophysiological effects of nonepithelial MR activation by aldosterone have been demonstrated in the context of inappropriate mineralocorticoid levels for salt status, including coronary vascular inflammation and cardiac fibrosis. These effects are mostly prevented by the concomitant administration of MR antagonists, but to date, no equivalent studies have determined whether MR blockade can reverse established inflammation and fibrosis. Uninephrectomized rats maintained on 0.9% NaCl solution to drink were treated as follows: group 1 served as controls; group 2 received deoxycorticosterone (DOC; 20 mg/wk) for 4 wk until death, and group 3 received DOC for 8 wk. Group 4 received DOC for 4 wk and no steroid from wk 5-8; group 5 received DOC for 8 wk and eplerenone in their chow during wk 5-8. DOC progressively raised cardiac collagen accumulation at 4 and 8 wk. Rats given DOC for 4 wk and killed at 8 wk showed levels of fibrosis identical to those in animals killed at 4 wk, i.e. persistently elevated above control values. Rats given DOC for 8 wk and eplerenone for the second half of the period showed cardiac collagen levels indistinguishable from control values. Values for inflammatory marker and NAD(P)H oxidase subunit expression in coronary vessels showed a similar pattern of response, with minor variation. Thus, MR antagonists do not only prevent cardiac fibrosis, but also reverse cardiac fibrosis once it is established. In addition, the continuing vascular inflammatory response and fibrosis after DOC withdrawal (group 4) support a role for activation of vascular MR by endogenous glucocorticoids in the context of tissue damage and generation of reactive oxygen species.

Topics: Animals; Biomarkers; Coronary Vessels; Desoxycorticosterone; Eplerenone; Fibrosis; Male; Mineralocorticoid Receptor Antagonists; Myocardium; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Sodium Chloride, Dietary; Spironolactone; Vasculitis

We examined the effect of different levels of salt intake on the role of aldosterone on cardiac and vascular changes in salt-loaded stroke-prone spontaneously hypertensive rats (SHRSP). Eleven-week-old SHRSP were fed high-salt (4.2% NaCl), normal-salt (0.28%), or low-salt (0.03%) diets with or without eplerenone (100 mg/kg per day, in food) for 5 weeks. A group of high-salt SHRSP was also treated with hydralazine (25 mg/kg per day). Blood pressure increased more in high-salt rats than in other groups (P<0.001). Eplerenone prevented further blood pressure rise in salt-loaded rats, with little effect on control and low-salt SHRSP. Increased media-to-lumen ratio of mesenteric resistance arteries induced by salt (P<0.01) was prevented by eplerenone (P<0.01). Maximal acetylcholine-induced vasodilation was impaired under salt loading (P<0.01), but improved under eplerenone (P<0.01). Eplerenone prevented (P<0.01) increased heart weight and left and right ventricular collagen deposition induced by high salt. Blood pressure lowering by hydralazine in high-salt SHRSP did not influence endothelial function or left ventricular collagen. Our study demonstrates salt-dependency of aldosterone effects on severity of hypertension, endothelial dysfunction, and cardiac and vascular remodeling in SHRSP. These effects were attenuated by eplerenone, particularly in the salt-loaded state, underlining the pathophysiological role of aldosterone in salt-sensitive hypertension.

Topics: Acetylcholine; Aldosterone; Animals; Antihypertensive Agents; Antioxidants; Blood Pressure; Collagen; Dose-Response Relationship, Drug; Endothelium, Vascular; Eplerenone; Fibrosis; Heart; Hydralazine; Hypertension; Male; Mesenteric Arteries; Mineralocorticoid Receptor Antagonists; Myocardium; Natriuresis; Organ Size; Rats; Rats, Inbred SHR; Receptors, Mineralocorticoid; Sodium Chloride, Dietary; Spironolactone; Thiobarbituric Acid Reactive Substances; Tunica Media; Vasodilation

Osteopontin (OPN) is upregulated in several experimental models of cardiac fibrosis and remodeling. However, its direct effects remain unclear. We examined the hypothesis that OPN is important for the development of cardiac fibrosis and remodeling. Moreover, we examined whether the inhibitory effect of eplerenone (Ep), a novel aldosterone receptor antagonist, was mediated through the inhibition of OPN expression against cardiac fibrosis and remodeling. Wild-type (WT) and OPN-deficient mice were treated with angiotensin II (Ang II) for 4 weeks. WT mice receiving Ang II were divided into 2 groups: a control group and an Ep treatment group. Ang II treatment significantly elevated blood pressure and caused cardiac hypertrophy and fibrosis in WT mice. Ep treatment and OPN deficiency could reduce the Ang II-induced elevation of blood pressure and ameliorate the development of cardiac fibrosis, whereas Ep-only treatment abolished the development of cardiac hypertrophy. Most compelling, the reduction of cardiac fibrosis led to an impairment of cardiac systolic function and subsequent left ventricular dilatation in Ang II-treated OPN-deficient mice. These results suggest that OPN has a pivotal role in the development of Ang II-induced cardiac fibrosis and remodeling. Moreover, the effect of Ep on the prevention of cardiac fibrosis, but not cardiac hypertrophy, might be partially mediated through the inhibition of OPN expression.

Topics: Aldosterone; Angiotensin II; Animals; Apoptosis; Blood Pressure; Cardiomegaly; Cell Size; Eplerenone; Fibrosis; Heart Rate; Hypertrophy, Left Ventricular; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Myocardium; Myocytes, Cardiac; Osteopontin; Reverse Transcriptase Polymerase Chain Reaction; Sialoglycoproteins; Spironolactone; Ultrasonography; Ventricular Remodeling

In epithelial tissues such as kidney, mineralocorticoid receptors (MR) are protected against glucocorticoid occupancy by the enzyme 11 beta-hydroxysteroid dehydrogenase (11 beta HSD) type 2. If the enzyme is congenitally inactive, or blocked by carbenoxolone, physiologic glucocorticoids act as MR agonists in such tissues. In most nonepithelial tissues, including cardiomyocytes, 11 beta HSD2 is expressed at minimal levels; in these tissues physiologic glucocorticoids act as MR antagonists, with the basis for this tissue selectivity currently unknown. Vascular smooth muscle cells (VSMC) express MR and 11 beta HSD1/2, with 11 beta HSD1 reported to show uncharacteristic oxidase activity, so that VSMC thus constitute a potential physiologic aldosterone target tissue. Because mineralocorticoid/salt administration triggers marked inflammatory responses in coronary vasculature, we reasoned that VSMC (like epithelial) MR may be activated by glucocorticoids if the protective enzyme is blocked. We thus gave uninephrectomized rats 0.9% NaCl solution to drink, and deoxycorticosterone (DOC, as a single 20 mg sc dose) or carbenoxolone (CBX, 2.5 mg/d in the drinking solution). Both DOC and CBX increased systolic blood pressure, heart, and kidney weight, and expression of cyclooxygenase 2, ED-1-positive macrophages, and osteopontin, with effects of both DOC and CBX blocked by the selective MR antagonist eplerenone. These findings suggest that local glucocorticoid excess, reflecting lower VSMC 11 beta HSD1/2 activity may mimic systemic mineralocorticoid excess, and play a direct etiologic role in coronary vascular inflammatory responses under circumstances of a high salt intake.

Topics: 11-beta-Hydroxysteroid Dehydrogenases; Animals; Blood Pressure; Carbenoxolone; Cardiomegaly; Coronary Disease; Desoxycorticosterone; Enzyme Inhibitors; Eplerenone; Fibrosis; Heart; Hydroxysteroid Dehydrogenases; Kidney; Male; Mineralocorticoid Receptor Antagonists; Muscle, Smooth, Vascular; Myocardium; Nephrectomy; Organ Size; Rats; Rats, Sprague-Dawley; Sodium Chloride; Solutions; Spironolactone; Vasculitis

We evaluated the role of aldosterone as a mediator of renal inflammation and fibrosis in a rat model of aldosterone/salt hypertension using the selective aldosterone blocker, eplerenone.. Unnephrectomized, Sprague-Dawley rats were given 1% NaCl (salt) to drink and randomized to receive treatment for 28 days: vehicle infusion (control); 0.75 microg/hour aldosterone subcutaneous infusion; or aldosterone infusion + 100 mg/kg/day oral dose of eplerenone. Blood pressure and urinary albumin were measured and kidneys were evaluated histologically. Renal injury, inflammation, and fibrosis were assessed by immunohistochemistry, in situ hybridization, and reverse transcription-polymerase chain reaction (RT-PCR).. Aldosterone/salt induced severe hypertension compared to controls (220 +/- 4 mm Hg vs. 131 +/- 4 mm Hg, P < 0.05), which was partially attenuated by eplerenone (179 +/- 4 mm Hg, P < 0.05). In aldosterone/salt treated rats, renal histopathologic evaluation revealed severe vascular and glomerular sclerosis, fibrinoid necrosis and thrombosis, interstitial leukocyte infiltration, and tubular damage and regeneration. Aldosterone/salt increased circulating osteopontin (925.0 +/- 80.2 ng/mL vs. 53.6 +/- 6.3 ng/mL) and albuminuria (75.8 +/- 10.9 mg/24 hours vs. 13.2 +/- 3.0 mg/24 hours) compared to controls and increased expression of proinflammatory molecules. Treatment with eplerenone reduced systemic osteopontin (58.3 +/- 4.2 ng/mL), albuminuria (41.5 +/- 7.2 mg/24 hours), and proinflammatory gene expression: osteopontin (OPN), monocyte chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6), and interleukin-1beta (IL-1beta).. These findings indicate that aldosterone/salt-induced renal injury and fibrosis has inflammatory components involving macrophage infiltration and cytokine up-regulation. Attenuation of renal damage and inflammation by eplerenone supports the protective effects of aldosterone blockade in hypertensive renal disease.

Topics: Aldosterone; Animals; Blood Pressure; Cytokines; Eplerenone; Fibrosis; Hypertension, Renal; Immunohistochemistry; In Situ Hybridization; Kidney; Macrophages; Male; Nephritis; Rats; Rats, Sprague-Dawley; Sodium Chloride; Spironolactone

Aldosterone classically promotes unidirectional transepithelial sodium transport, thereby regulating blood volume and blood pressure. Recently, both clinical and experimental studies have suggested additional, direct roles for aldosterone in the cardiovascular system. To evaluate aldosterone activation of cardiomyocyte mineralocorticoid receptors, transgenic mice overexpressing 11beta-hydroxysteroid dehydrogenase type 2 in cardiomyocytes were generated using the mouse alpha-myosin heavy chain promoter. This enzyme converts glucocorticoids to receptor-inactive metabolites, allowing aldosterone occupancy of cardiomyocyte mineralocorticoid receptors. Transgenic mice were normotensive but spontaneously developed cardiac hypertrophy, fibrosis, and heart failure and died prematurely on a normal salt diet. Eplerenone, a selective aldosterone blocker, ameliorated this phenotype. These studies confirm the deleterious consequences of inappropriate activation of cardiomyocyte mineralocorticoid receptors by aldosterone and reveal a tonic inhibitory role of glucocorticoids in preventing such outcomes under physiological conditions. In addition, these data support the hypothesis that aldosterone blockade may provide additional therapeutic benefit in the treatment of heart failure.

Topics: 11-beta-Hydroxysteroid Dehydrogenase Type 2; Aldosterone; Animals; Blood Pressure; Cardiomegaly; Disease Models, Animal; Echocardiography; Eplerenone; Female; Fibrosis; Gene Expression Regulation; Gene Expression Regulation, Enzymologic; Heart Failure; Hydroxysteroid Dehydrogenases; Kidney; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Mineralocorticoid Receptor Antagonists; Myocardium; Myocytes, Cardiac; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Spironolactone; Up-Regulation; Ventricular Dysfunction, Left

Myocardial infarction (MI) initiates adaptive tissue remodeling, which is essential for heart function (such as infarct healing) but is also important for maladaptive remodeling (for example, reactive fibrosis and left ventricular dilation). The effect of aldosterone receptor antagonism on these processes was evaluated in Sprague-Dawley rats using eplerenone, a selective aldosterone receptor antagonist. Infarct healing and left ventricular remodeling were evaluated at 3, 7, and 28 days after MI by determination of the diastolic pressure-volume relationship of the left ventricle, the infarct-thinning ratio, and the collagen-volume fraction. Eplerenone did not affect reparative collagen deposition as was evidenced by a similar collagen volume fraction in the infarcted myocardium between eplerenone and vehicle-treated groups at 7 and 28 days post-MI. In addition, the thinning ratio, which is an index of infarct expansion, was comparable between the eplerenone and vehicle-treated animals at 7 and 28 days post-MI. A protective effect of eplerenone was demonstrated at 28 days post-MI, where reactive fibrosis in the viable myocardium was reduced in eplerenone-treated animals compared with vehicle-treated animals. Thus aldosterone receptor antagonism does not retard infarct healing but rather protects against maladaptive responses after MI.

Topics: Animals; Eplerenone; Fibrosis; Male; Mineralocorticoid Receptor Antagonists; Myocardial Infarction; Rats; Rats, Sprague-Dawley; Receptors, Mineralocorticoid; Spironolactone; Ventricular Remodeling