Regulation of aldosterone secretion in patients with chronic congestive heart failure by endothelins

Promising Therapeutic Treatments for Cardiac Fibrosis: Herbal Plants and Their Extracts

Cardiac fibrosis is closely associated with multiple heart diseases, which are a prominent health issue in the global world. Neurohormones and cytokines play indispensable roles in cardiac fibrosis. Many signaling pathways participate in cardiac fibrosis as well. Cardiac fibrosis is due to impaired degradation of collagen and impaired fibroblast activation, and collagen accumulation results in increasing heart stiffness and inharmonious activity, leading to structure alterations and finally cardiac function decline. Herbal plants have been applied in traditional medicines for thousands of years. Because of their naturality, they have attracted much attention for use in resisting cardiac fibrosis in recent years. This review sheds light on several extracts from herbal plants, which are promising therapeutics for reversing cardiac fibrosis.

New Dual Endothelin Receptor Antagonist Aprocitentan in Hypertension: A Systematic Review and Meta-Analysis

Hypertension is one of the most common disorders encountered, yet pharmacotherapy for resistant hypertension has limited effective options. Aprocitentan is postulated to be a novel anti-hypertensive. The main goal was to determine the effect of aprocitentan on blood pressure among patients with hypertension. A thorough search of five electronic databases, including PubMed Central, PubMed, EMBASE, Springer, and Google Scholar, was carried out. The study included nine articles with a total of 2024 participants. With doses exceeding 25 mg, plasma ET-1(endothelin-1) concentrations, which show ETB (Endothelin receptor type B) receptor antagonism, significantly rose. Aprocitentan significantly reduced systolic and diastolic blood pressure with both doses of 10mg and 25mg in patients with hypertension. Further research is warranted to evaluate the efficacy, safety, and long-term outcomes of aprocitentan and its synergistic effect with other anti-hypertensives.

Effects of the Dual Endothelin Receptor Antagonist Aprocitentan on Body Weight and Fluid Homeostasis in Healthy Subjects on a High Sodium Diet

Aprocitentan is a novel, oral, dual endothelin receptor antagonist (ERA) in development in difficult-to-control hypertension. As fluid retention and edema are concerns with ERAs, we investigated whether aprocitentan causes weight gain in healthy subjects on a high sodium diet and explored potential mechanisms if occurring. This double-blind, randomized, placebo-controlled, crossover study enrolled 28 subjects. Three doses of aprocitentan (10, 25, or 50 mg/day for 9 days) were compared with placebo. Increases in body weight were observed with aprocitentan (placebo-corrected mean weight gains [90% confidence interval]) of 0.43 [0.05-0.80], 0.77 [0.03-1.51], and 0.83 [0.33-1.32] kg at 10 mg, 25 mg, and 50 mg, respectively. Decreases in hemoglobin and uric acid were observed. Plasma volume increased at most by 5.5% without dose-response relationship. Urinary sodium excretion decreased at 10 mg and 25 mg but not at 50 mg. Therefore, aprocitentan produced moderate weight increases in healthy subjects on high sodium diet, without obvious sodium retention.

Long-Term Effect of Endothelin Receptor Antagonism With Bosentan on the Morbidity and Mortality of Patients With Severe Chronic Heart Failure: Primary Results of the ENABLE Trials

OBJECTIVES

The objective of this clinical trial was to evaluate the long-term effect of endothelin receptor antagonism with bosentan on the morbidity and mortality of patients with severe chronic heart failure.

BACKGROUND

Endothelin may play a role in heart failure, but short-term clinical trials with endothelin receptor antagonists have reported disappointing results. Long-term trials are lacking.

METHODS

In 2 identical double-blind trials, we randomly assigned 1,613 patients with New York Heart Association functional class IIIb to IV heart failure and an ejection fraction <35% to receive placebo or bosentan (target dose 125 mg twice daily) for a median of 1.5 years. The primary outcome for each trial was clinical status at 9 months (assessed by the hierarchical clinical composite); the primary outcome across the 2 trials was death from any cause or hospitalization for heart failure.

RESULTS

Bosentan did not influence clinical status at 9 months in either trial (p = 0.928 and p = 0.263). In addition, 321 patients in the placebo group and 312 patients in the bosentan group died or were hospitalized for heart failure (hazard ratio [HR]: 1.01; 95% confidence interval [CI]: 0.86 to 1.18; p = 0.90). The bosentan group experienced fluid retention within the first 2 to 4 weeks, as evidenced by increased peripheral edema, weight gain, decreases in hemoglobin, and an increased risk of hospitalization for heart failure, despite intensification of background diuretics. During follow-up, 173 patients died in the placebo group and 160 patients died in the bosentan group (HR: 0.94; 95% CI: 0.75 to 1.16). About 10% of the bosentan group showed meaningful increases in hepatic transaminases, but none had acute or chronic liver failure.

CONCLUSIONS

Bosentan did not improve the clinical course or natural history of patients with severe chronic heart failure and but caused early and important fluid retention.

Dual Endothelin-A/Endothelin-B Receptor Blockade and Cardiac Remodeling in Heart Failure With Preserved Ejection Fraction

BACKGROUND

Despite the increasing prevalence of heart failure with preserved ejection fraction (HFpEF) in humans, there remains no evidence-based therapies for HFpEF. Endothelin-1 (ET-1) antagonists are a possibility because elevated ET-1 levels are associated with adverse cardiovascular effects, such as arterial and pulmonary vasoconstriction, impaired left ventricular (LV) relaxation, and stimulation of LV hypertrophy. LV hypertrophy is a common phenotype in HFpEF, particularly when associated with hypertension.

METHODS AND RESULTS

In the present study, we found that ET-1 levels were significantly elevated in patients with chronic stable HFpEF. We then sought to investigate the effects of chronic macitentan, a dual ET-A/ET-B receptor antagonist, on cardiac structure and function in a murine model of HFpEF induced by chronic aldosterone infusion. Macitentan caused LV hypertrophy regression independent of blood pressure changes in HFpEF. Although macitentan did not modulate diastolic dysfunction in HFpEF, it significantly reduced wall thickness and relative wall thickness after 2 weeks of therapy. In vitro studies showed that macitentan decreased the aldosterone-induced cardiomyocyte hypertrophy. These changes were mediated by a reduction in the expression of cardiac myocyte enhancer factor 2a. Moreover, macitentan improved adverse cardiac remodeling, by reducing the stiffer cardiac collagen I and titin n2b expression in the left ventricle of mice with HFpEF.

CONCLUSIONS

These findings indicate that dual ET-A/ET-B receptor inhibition improves HFpEF by abrogating adverse cardiac remodeling via antihypertrophic mechanisms and by reducing stiffness. Additional studies are needed to explore the role of dual ET-1 receptor antagonists in patients with HFpEF.

Comparison of Macitentan and Bosentan on Right Ventricular Remodeling in a Rat Model of Non-vasoreactive Pulmonary Hypertension

Supplemental Digital Content Is Available in the Text.

We compared the efficacy of macitentan, a novel dual endothelin A/endothelin B receptor antagonist, with that of another dual endothelin receptor antagonist, bosentan, in a rat model of non-vasoreactive pulmonary hypertension (PH) with particular emphasis on right ventricular (RV) remodeling.

Pulmonary hypertension in canine degenerative mitral valve disease

Pulmonary hypertension secondary to degenerative mitral valve disease has been recognized clinically for many years in veterinary medicine, and clinical diagnosis of this syndrome in dogs has been enhanced greatly by widespread use of echocardiography and Doppler echocardiography. Medical therapy is now available to treat this clinical complication of mitral valve disease, making timely diagnosis even more important to patient longevity and quality of life.

At the heart of tissue: endothelin system and end-organ damage

ET (endothelin)-1 was first described as a potent vasoconstrictor. Since then, many other deleterious properties mediated via its two receptors, ETA and ETB, have been described, such as inflammation, fibrosis and hyperplasia. These effects, combined with a wide tissue distribution of the ET system, its up-regulation in pathological situations and a local autocrine/paracrine activity due to a high tissue receptor binding, make the tissue ET system a key local player in end-organ damage. Furthermore, ET-1 interacts in tissues with other systems such as the RAAS (renin-angiotensin-aldosterone system) to exert its effects. In numerous genetically modified animal models, non-specific or organ-targeted ET-1 overexpression causes intense organ damage, especially hypertrophy and fibrosis, in the absence of haemodynamic changes, confirming a local activity of the ET system. ET receptor antagonists have been shown to prevent and sometimes reverse these tissue alterations in an organ-specific manner, leading to long-term benefits and an improvement in survival in different animal models. Potential for such benefits going beyond a pure haemodynamic effect have also been suggested by clinical trial results in which ET receptor antagonism decreased the occurrence of new digital ulcers in patients with systemic sclerosis and delayed the time to clinical worsening in patients with PAH (pulmonary arterial hypertension). The tissue ET system allows therapeutic interventions to provide organ selectivity and beneficial effects in diseases associated with tissue inflammation, hypertrophy or fibrosis.

Endothelins: Pathophysiology and treatment implications in chronic heart failure

Less than 20 years after its discovery, endothelin is recognized as playing a central role in the pathogenesis of chronic heart failure. Endothelin is not only one of the most potent known vasoconstrictors; it also has multiple other actions. It mediates pathologic hypertrophy and fibrosis of both ventricular and vascular tissues, it potentiates the effects of other neurohormones, and it acts as a proarrhythmic. Endothelin receptor antagonists have been developed to investigate the hypothesis that these adverse effects could be prevented, and experimental studies showed promise in this regard. Clinical studies have confirmed the ability of these new agents to improve hemodynamics, but beneficial effects on clinical outcomes have been more difficult to demonstrate. Further analysis of the data from these trials, as well as other ongoing studies, may provide insight into these disparate findings and guidance for future investigations.

Clinical effects of endothelin receptor antagonism with bosentan in patients with severe chronic heart failure: results of a pilot study

BACKGROUND

Endothelin receptor antagonism produces favorable short-term hemodynamic effects in heart failure, but the clinical effects of longer term therapy have not been evaluated.

METHODS AND RESULTS

Three hundred and seventy patients with symptoms of heart failure at rest or on minimal exertion and a left ventricular ejection fraction <35% were randomly assigned (double-blind) to placebo (n = 126) or the endothelin receptor antagonist bosentan, titrated slowly (n = 121) or rapidly (n = 123) to a target dose of 500 mg twice daily. Treatment with the study drug was to be maintained for 26 weeks, whereas background medications for heart failure were kept constant. Safety concerns led to early termination of the trial when only 174 patients had had an opportunity to complete 26 weeks of therapy. Bosentan exerted no apparent benefit when all randomized patients were analyzed (P = .709). However, in the first 174 patients who were recruited at least 26 weeks before study termination and who could therefore be followed for the planned duration of the trial, patients in the bosentan groups were more likely to be improved (26% versus 19%) and were less likely to be worse (28% versus 43%), P = .045. When compared with placebo-treated patients, bosentan-treated patients had a increased risk of heart failure during the first month of treatment but a decreased risk of heart failure during the fourth, fifth, and sixth months of therapy. The major noncardiac adverse effects of bosentan included an increase in hepatic transaminases (in 15.6% of patients) and a decrease in hemoglobin (of about 1 g/L).

CONCLUSION

Although bosentan exerted no favorable effects in the overall study, our findings suggest that the clinical responses to endothelin antagonism with bosentan in patients with severe chronic heart failure may be dependent on the duration of treatment.

Endothelin???aldosterone interaction and proteinuria in low-renin hypertension

OBJECTIVE

To investigate whether endothelin and aldosterone participate in the increased prevalence and severity of nephrosclerosis in human low-renin hypertension, analogous to observations in experimental hypertension.

DESIGN

Comparison of endothelin, aldosterone and their relationships with proteinuria, in hypertensive patients with high aldosterone : renin ratios (HARR group, n = 14) or normal aldosterone : renin ratios (NARR group, n = 15).

METHODS

Urine protein and radioimmunoassay measurements of plasma renin activity, endothelin and aldosterone were carried out in individuals taking their usual diet, and after salt loading and salt depletion.

RESULTS

Compared with the NARR group, patients in the HARR group had higher blood pressure, greater salt sensitivity of their blood pressure, significantly greater urine protein and lower serum potassium concentrations, lower renin activities [0.14 +/- 0.03 ng AngiotensinI (AI)/l per s compared with 0.76 +/- 0.16 ng AI/l per s; P < 0.005], blunted renin-aldosterone responses to salt loading and salt depletion, enhanced catecholamine responses to salt depletion, and increased plasma endothelin (5.1 +/- 0.5 fmol/ml compared with 3.7 +/- 0.3 fmol/ml; P < 0.03). In the HARR group, endothelin and aldosterone concentrations were highly correlated, and both correlated with blood pressure and urine protein. In contrast, in the NARR group, endothelin and aldosterone did not correlate between them or with blood pressure, and only endothelin, not aldosterone, correlated with urine protein. Multivariate regression confirmed that the interaction between aldosterone and endothelin was the major predictor of urine protein in the HARR group (r = 0.442), whereas endothelin, renin and their interaction were predictors in the NARR group (r = 0.467).

CONCLUSIONS

Our results concur with experimental evidence for participation of endothelin in renal damage of angiotensin-dependent hypertension and for that of an endothelin-aldosterone interaction in low-renin hypertension. We propose that combined pharmacological antagonism of endothelin and aldosterone may confer renal protection beyond blood pressure reduction in patients with low-renin hypertension, a population at high risk for hypertensive nephrosclerosis.

Acute decompensated heart failure: a contemporary approach to pharmacotherapeutic management

Hospital admissions for acute decompensated heart failure (ADHF) have increased precipitously during the past few decades and are projected to continue to increase in the future. To optimize patient outcomes and reduce the costs associated with this disorder, evidenced-based pharmacotherapy is essential. Continuous infusions of loop diuretic therapy rather than bolus dosing may enhance efficacy and reduce the extent of diuretic resistance. Nesiritide is a pharmacologically novel preload and afterload reducer but based on clinical trial evidence should be reserved for those unable to take or with resistance to intravenous nitrate therapy. Catecholamine- and phosphodiesterase-based inotropic therapies are efficacious, but the increased risk of arrhythmogenesis and the potential for negative survival effects limit their use. The experimental agent levosimendan is a positive inotropic agent but does not increase myocyte calcium concentrations as do catecholamines or phosphodiesterase inhibitors. Clinical trial evidence demonstrates a positive survival benefit for levosimendan versus dobutamine.

The endothelin system and its role in acute myocardial infarction

Immediately after an acute myocardial infarction (AMI) or in models of ischemia-reperfusion injury, cardiac endothelin (ET) system is markedly activated, and plasma levels of ET are increased. In the heart, expression of the main components of the ET system (ET-1 peptide, both receptor subtypes ETA and ETB, though not endothelin converting enzyme) are increased both at the gene level and protein level, in the viable myocardium, and--even more substantially--in the necrotic area. Despite these conspicuous abnormalities, the role of ET in this setting remains unclear. In the absence of human data, most short-term studies in animals (in terms of hours to up to 8 days post-AMI) and in the reperfused ischemic heart, have found beneficial effects of ET receptor blockade on survival rate, incidence of arrhythmias, cardiac function, and morphology. In contrast, many studies in which a long-term ET inhibition was started immediately post-infarction and the late effects were examined in animals with ensuing chronic heart failure (14-100 days postinfarction), adverse effects were also observed, such as scar thinning, further ventricular dilation, or even a worse survival rate. It appears that the ET system plays a dual role during the early post-AMI period. At present, it is not clear whether the short-term beneficial effects or long-term adverse effects of ET receptor blockade would prevail. Acute use of short-acting ET receptor antagonists in patients with AMI complicated by an acute heart failure is an attractive possibility that also remains to be investigated.

Role of endothelins in congestive heart failure

Despite major advances in conventional medical therapy, patients with heart failure continue to experience significant morbidity and mortality. Endothelin-1 (ET-1) is a potent vasocontrictor and mitogenic peptide that is activated in heart failure. There is increasing experimental and clinical evidence in support of an important role of ET-1 in the pathophysiology of heart failure. Manipulation of the activity of ET-1, especially using endothelin receptor blockers, has allowed for the further elucidation of the role of this neurohormonal system and development of novel therapeutic strategies in heart failure. Published clinical studies of these agents to date have involved relatively small numbers of patients with severe heart failure, followed for a relatively short period of time, and have mainly examined surrogate endpoints. Large-scale trials that address to hard clinical outcomes are ongoing and their results forthcoming. A key question that remains concerns whether selective ETA or dual ETA-ETB receptor blockade will be more effective.

Hemodynamic effects of bosentan in patients with chronic heart failure

A role of the potent and long-acting vasoconstrictor peptide endothelin-1 and the pathophysiology of chronic human heart failure has been postulated based upon indirect evidence such as elevated plasma endothelin-1 levels and their with the degree of hemodynamic impairment. The advent of specific of endothelin-1 receptor antagonists has provided the opportunity not only to directly evaluate its pathophysiological role but also to assess its potential role as a new approach to heart failure therapy. This brief review summarizes the evidence linking endothelin-1 to the pathophysiology of chronic heart failure and the clinical results obtained in patients during acute, intravenous and more prolonged, oral administration with bosentan, a mixed ET(A)/ET(B)-receptor antagonist. Bosentan acutely and during short-term oral therapy markedly improved hemodynamics in patients in addition to standard heart failure therapy, including an ACE-inhibitor. These effects were associated with a reduced responsiveness of the renin-angiotensin system to diuretic therapy and reduced basal plasma aldosterone levels. Although the hemodynamic and neurohumoral profile of short-term bosentan therapy looks promising for the treatment of patients with chronic heart failure appropriate trials will have to be performed to document clinical benefit during long-term therapy. Finally, the question remains open whether mixed endothelin-1 receptor antagonists like bosentan will have similar effects as compared to antagonists which block the ET(A) receptor only.

Clinical experience with endothelin receptor antagonists in chronic heart failure

Both ET(A) selective and dual, ET(A/B), receptor antagonists have favourable short- and longer-term haemodynamic actions in patients with acute and chronic heart failure. Their effect on neurohumoral measures is not yet fully determined. Two moderately large, medium-duration studies have examined the effect of dual ET(A/B) receptor antagonists on clinical status, reaching conflicting conclusions. One large scale, long-term, morbidity mortality evaluation is underway with bosentan.

Influence of aldosterone vs. endothelin receptor antagonism on renovascular function in liquorice-induced hypertension

BACKGROUND

The enzyme 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) provides mineralocorticoid receptor specificity for aldosterone by metabolizing glucocorticoids to their receptor inactive 11-dehydro derivatives. Inhibition of 11beta-HSD2 by liquorice-derived glycyrrhizic acid (GA) therefore results in sodium retention and hypertension. The present study investigated the effect of the aldosterone receptor antagonist spironolactone in comparison with the endothelin ET(A) receptor antagonist darusentan on renovascular endothelial function in liquorice-induced hypertension.

METHODS

GA, a recognized inhibitor of 11beta-HSD2 was supplemented to the drinking water (3 g/l) of Wistar Kyoto rats over a period of 21 days. From day 8 to 21, spironolactone (5.8+/-0.6 mg/kg/day), darusentan (45.2+/-6.5 mg/kg/day), or placebo was added to chow (n=7 per group). After the animals were killed, vascular function of isolated renal artery segments was assessed by isometric tension recording.

RESULTS

Relaxation of pre-constricted renal artery segments in response to acetylcholine (10(-10) to 10(-5) mol/l) was impaired by GA as compared with controls (12+/-4% vs 98+/-5% of norepinephrine 3x10(-7) mol/l), whereas endothelium independent relaxations were unaffected. Endothelin receptor antagonism improved renovascular endothelium-dependent relaxation (32+/-4%, P<0.05 vs placebo) whereas endothelium-dependent relaxation was completely normalized by aldosterone receptor antagonism (85+/-4%, P<0.01 vs placebo).

CONCLUSIONS

In GA-induced hypertension, both aldosterone receptor antagonism and endothelin receptor antagonism normalize blood pressure and improve renovascular function and, thus, may represent a new therapeutic approach in cardiovascular disease associated with impaired 11beta-HSD2 activity.

Bosentan, an endothelin antagonist, augments hepatic graft function by reducing graft circulatory impairment following ischemia/reperfusion injury

Endothelin is a potent hepatic vasoconstrictor. We evaluated the role of an endothelin antagonist in hepatic ischemia/reperfusion injury. Bosentan, a novel endothelin receptor antagonist, was infused directly into the portal vein prior to cold ischemia and immediately on reperfusion, in five porcine livers. Five other pigs underwent routine liver harvest and reperfusion without bosentan treatment. Hepatic vascular resistance and liver tissue blood flow, as measured by thermistor flow probes, were determined following reperfusion. Hepatocellular damage was assessed through hepatic venous levels of sorbitol dehydrogenase and lactate dehydrogenase. Endothelial cell damage was determined in sections immuno-stained for factor VIII. Graft function was determined through oxygen consumption, bile production, and response to bile acid challenge. Organs treated with bosentan demonstrated lower vascular resistance and enhanced tissue blood flow (P < 0.05) as compared to untreated organs. Portal vein inflow to hepatic tissue was significantly enhanced (4.4-fold) in the bosentan-treated organs (P < 0.05). No difference was observed in hepatocellular damage. Pathology scores for factor VIII immunohistochemical staining were 2.3-fold higher in the bosentan-treated livers as compared to untreated livers (P < 0.05). The bosentan-treated livers also demonstrated enhanced oxygen consumption, increased bile production, and augmented biliary response to a bile acid challenge (P < 0.05). These results indicate that administration of bosentan before and after ischemia/reperfusion reduces hepatic circulatory disturbances, diminishes endothelial cell damage, and augments hepatic graft function.

The role of endothelin receptor antagonists in the treatment of chronic heart failure

A role of the potent and long-acting vasoconstrictor peptide endothelin-1 in the pathophysiology of chronic human heart failure has been postulated based on indirect evidence such as elevated plasma endothelin-1 levels, their correlation with the degree of hemodynamic impairment, and their predictive value for patient survival. The advent of specific of endothelin-1 receptor antagonists has provided the opportunity to directly evaluate its pathophysiologic role and assess its potential role as a new approach to heart failure therapy. This review summarizes the evidence linking endothelin-1 to the pathophysiology of chronic heart failure, and analyzes the clinical results obtained thus far in patients during acute intravenous, and more prolonged, oral administration of endothelin-1-receptor antagonists.

Endothelin as a therapeutic target in the treatment of cardiovascular disease

Endothelins, a family of peptides derived from the vascular endothelium and smooth muscle cells possess vasoconstrictor and mitogenic properties. By acting predominantly in a paracrine fashion, these peptides activate specific receptors and have protean effects in normal and diseased organ systems. The wide distribution of these receptors in various tissues mediate the multiplicity of physiologic actions attributed to endothelins. Much of our understanding about endothelins has come from the development of an array of receptor-specific and mixed receptor antagonists. Based on the promising results from animal studies, active research and drug development programs are under way to investigate the clinical potential of endothelin antagonism for treatment of cardiovascular disease.

Aldosterone receptor antagonism normalizes vascular function in liquorice-induced hypertension

The enzyme 11beta-hydroxysteroid dehydrogenase (11beta-HSD2) provides mineralocorticoid receptor specificity for aldosterone by metabolizing glucocorticoids to their receptor-inactive 11-dehydro derivatives. The present study investigated the effects of the aldosterone receptor antagonists spironolactone and eplerenone on endothelial function in liquorice-induced hypertension. Glycyrrhizic acid (GA), a recognized inhibitor of 11beta-HSD2, was supplemented to the drinking water (3 g/L) of Wistar-Kyoto rats over a period of 21 days. From days 8 to 21, spironolactone (5.8+/-0.6 mg. kg(-1). d(-1)), eplerenone (182+/-13 mg. kg(-1). d(-1)), or placebo was added to the chow (n=7 animals per group). Endothelium-dependent or -independent vascular function was assessed as the relaxation of preconstricted aortic rings to acetylcholine or sodium nitroprusside, respectively. In addition, aortic endothelial nitric oxide synthase (eNOS) protein content, nitrate tissue levels, and endothelin-1 (ET-1) protein levels were determined. GA increased systolic blood pressure from 142+/-8 to 185+/-9 mm Hg (P<0.01). In the GA group, endothelium-dependent relaxation was impaired compared with that in controls (73+/-6% versus 99+/-5%), whereas endothelium-independent relaxation remained unchanged. In the aortas of 11beta-HSD2-deficient rats, eNOS protein content and nitrate tissue levels decreased (1114+/-128 versus 518+/-77 microgram/g protein, P<0.05). In contrast, aortic ET-1 protein levels were enhanced by GA (308+/-38 versus 497+/-47 pg/mg tissue, P<0.05). Both spironolactone and eplerenone normalized blood pressure in animals on GA (142+/-9 and 143+/-9 mm Hg, respectively, versus 189+/-8 mm Hg in the placebo group; P<0.01), restored endothelium-dependent relaxation (96+/-3% and 97+/-3%, respectively, P<0.01 versus placebo), blunted the decrease in vascular eNOS protein content and nitrate tissue levels, and normalized vascular ET-1 levels. This is the first study to demonstrate that aldosterone receptor antagonism normalizes blood pressure, prevents upregulation of vascular ET-1, restores NO-mediated endothelial dysfunction, and thus, may advance as a novel and specific therapeutic approach in 11beta-HSD2-deficient hypertension.