Comparison of inhibitory effects of irbesartan and atorvastatin treatment on the renin angiotensin system (RAS) in veins: a randomized double-blind crossover trial in healthy subjects

Insulinotropic Effects of Neprilysin and/or Angiotensin Receptor Inhibition in Mice

Treatment of heart failure with the angiotensin receptor-neprilysin inhibitor sacubitril/valsartan improved glycemic control in individuals with type 2 diabetes. The relative contribution of neprilysin inhibition versus angiotensin II receptor antagonism to this glycemic benefit remains unknown. Thus, we sought to determine the relative effects of the neprilysin inhibitor sacubitril versus the angiotensin II receptor blocker valsartan on beta-cell function and glucose homeostasis in a mouse model of reduced first-phase insulin secretion, and whether any beneficial effects are additive/synergistic when combined in sacubitril/valsartan. High fat-fed C57BL/6J mice treated with low-dose streptozotocin (or vehicle) were followed for eight weeks on high fat diet alone or supplemented with sacubitril, valsartan or sacubitril/valsartan. Body weight and fed glucose levels were assessed weekly. At the end of the treatment period, insulin release in response to intravenous glucose, insulin sensitivity, and beta-cell mass were determined. Sacubitril and valsartan, but not sacubitril/valsartan, lowered fasting and fed glucose levels and increased insulin release in diabetic mice. None of the drugs altered insulin sensitivity or beta-cell mass, but all reduced body weight gain. Effects of the drugs on insulin release were reproduced in angiotensin II-treated islets from lean C57BL/6J mice, suggesting the insulin response to each of the drugs is due to a direct effect on islets and mechanisms therein. In summary, sacubitril and valsartan each exert beneficial insulinotropic, glycemic and weight-reducing effects in obese and/or diabetic mice when administered alone; however, when combined, mechanisms within the islet contribute to their inability to enhance insulin release.

Atrial appendage angiotensin-converting enzyme-2, aging and cardiac surgical patients: a platform for understanding aging-related coronavirus disease-2019 vulnerabilities

PURPOSE OF REVIEW

Hospitalizations for COVID-19 dramatically increase with age. This is likely because of increases in fragility across biological repair systems and a weakened immune system, including loss of the cardiorenal protective arm of the renin--angiotensin system (RAS), composed of angiotensin-converting enzyme-2 (ACE2)/angiotensin-(1--7) [Ang-(1--7)] and its actions through the Mas receptor. The purpose of this review is to explore how cardiac ACE2 changes with age, cardiac diseases, comorbid conditions and pharmaceutical regimens in order to shed light on a potential hormonal unbalance facilitating SARs-CoV-2 vulnerabilities in older adults.

RECENT FINDINGS

Increased ACE2 gene expression has been reported in human hearts with myocardial infarction, cardiac remodeling and heart failure. We also found ACE2 mRNA in atrial appendage tissue from cardiac surgical patients to be positively associated with age, elevated by certain comorbid conditions (e.g. COPD and previous stroke) and increased in conjunction with patients' chronic use of antithrombotic agents and thiazide diuretics but not drugs that block the renin--angiotensin system.

SUMMARY

Cardiac ACE2 may have bifunctional roles in COVID-19 as ACE2 not only mediates cellular susceptibility to SARS-CoV-2 infection but also protects the heart via the ACE2/Ang-(1--7) pathway. Linking tissue ACE2 from cardiac surgery patients to their comorbid conditions and medical regimens provides a unique latform to address the influence that altered expression of the ACE2/Ang-(1-7)/Mas receptor axis might have on SARs-CoV-2 vulnerability in older adults.

Angiotensin II receptor blocker attenuates stress pressor response in young adult African Americans

African Americans (AAs) are susceptible to hypertension (HTN) and its associated organ damage leading to adverse cardiovascular (CV) outcomes. Psychological stress is proposed to contribute to the development of HTN; however, the potential role of the renin-angiotensin system (RAS) in stress-related HTN in AAs is largely unknown. In this study, we tested the hypothesis that activation of RAS is a potential contributing factor for altered CV responses to stress, and suppression of angiotensin II (Ang II) activity will improve hemodynamic responses to a prolonged mental stressor in healthy young AAs. Utilizing a double-blind, randomized, crossover study design, 132 normotensive AAs (25 ± 7 years) were treated with either a placebo (PLC) or 150 mg/d irbesartan (an Ang II type 1 receptor blocker; ARB) for 1 week. On the final day of each treatment, hemodynamic measures and urinary sodium excretion (UNaV) were collected before, during and after a 45 minute-mental stress. The magnitude of stress-induced increase in blood pressure with ARB was blunted and delayed compared to PLC. Systolic blood pressure at the end of recovery on ARB was significantly lower compared to either PLC (110 ± 13 vs 117 ± 12 mm Hg respectively; P < 0.001) or the prestress level on ARB (P = 0.02). ARB treatment reduced overall vasoconstriction and improved poststress UNaV. ARB attenuated blood pressure responses to mental stress and improved the poststress BP recovery process which were partly linked to reduced overall vasoconstriction and improved stress-induced UNaV in young adult AAs prior to the development of disease conditions. These results suggest that treatment approaches that inhibit RAS action could have significant relevance to potentially lower susceptibility to stress responses and eventually the premature development of HTN in AAs.

Review: The metabolic syndrome as an endocrine disease: is there an effective pharmacotherapeutic strategy optimally targeting the pathogenesis?

The metabolic syndrome (MetS) represents a combination of cardiovascular risk determinants such as obesity, insulin resistance and lipid abnormalities such as hypertriglyceridemia, increased free fatty acids, low high-density-cholesterol and hypertension. As a multiple component condition it imparts a doubling of relative risk for atherosclerotic cardiovascular disease (ASCVD). It is currently controversial which component of the syndrome carries what weight. There is even a considerable debate whether the risk for ASCVD is greater in patients diagnosed with MetS than that by the individual risk factors. At present, no unifying pathogenetic mechanism can explain the metabolic syndrome and there is no unique treatment for it. This review summarizes and critically reviews the currently available clinical and scientific evidence for the concept that the MetS is causally an endocrine disease and discusses pharmacotherapeutic strategies targeting the pathogenesis rather than single symptoms of the cluster.

Stop chronic kidney disease progression: Time is approaching

Progression of chronic kidney disease (CKD) is inevitable. However, the last decade has witnessed tremendous achievements in this field. Today we are optimistic; the dream of withholding this progression is about to be realistic. The recent discoveries in the field of CKD management involved most of the individual diseases leading the patients to end-stage renal disease. Most of these advances involved patients suffering diabetic kidney disease, chronic glomerulonephritis, polycystic kidney disease, renal amyloidosis and chronic tubulointerstitial disease. The chronic systemic inflammatory status and increased oxidative stress were also investigated. This inflammatory status influences the anti-senescence Klotho gene expression. The role of Klotho in CKD progression together with its therapeutic value are explored. The role of gut as a major source of inflammation, the pathogenesis of intestinal mucosal barrier damage, the role of intestinal alkaline phosphatase and the dietary and therapeutic implications add a novel therapeutic tool to delay CKD progression.

Angiotensin-(1-7): new perspectives in atherosclerosis treatment

Angiotensin (Ang)-(1-7) is recognized as a new bioactive peptide in renin-angiotensin system (RAS). Ang-(1-7) is a counter-regulatory mediator of Ang-II which appears to be protective against cardiovascular disease. Recent studies have found that Ang-(1-7) played an important role in reducing smooth muscle cell proliferation and migration, improving endothelial function and regulating lipid metabolism, leading to inhibition of atherosclerotic lesions and increase of plaque stability. Although clinical application of Ang-(1-7) is restricted due to its pharmacokinetic properties, identification of stabilized compounds, including more stable analogues and specific delivery compounds, has enabled clinical application of Ang-(1-7). In this review, we discussed recent findings concerning the biological role of Ang-(1-7) and related mechanism during atherosclerosis development. In addition, we highlighted the perspective to develop therapeutic strategies using Ang-(1-7) to treat atherosclerosis.

Statin treatment in hypercholesterolemic men does not attenuate angiotensin II-induced venoconstriction

Experimental studies suggested that statins attenuate vascular AT1 receptor responsiveness. Moreover, the augmented excessive pressor response to systemic angiotensin II infusions in hypercholesterolemic patients was normalized with statin treatment. In 12 hypercholesterolemic patients, we tested the hypothesis that statin treatment attenuates angiotensin II-mediated vasoconstriction in hand veins assessed by a linear variable differential transducer. Subjects ingested daily doses of either atorvastatin (40 mg) or positive control irbesartan (150 mg) for 30 days in a randomized and cross-over fashion. Ang II-induced venoconstriction at minute 4 averaged 59%±10% before and 28%±9% after irbesartan (mean ± SEM; P<0.05) compared to 65%±11% before and 73%±11% after 30 days of atorvastatin treatment. Plasma angiotensin levels increased significantly after irbesartan treatment (Ang II: 17±22 before vs 52±40 pg/mL after [p = 0.048]; Ang-(1-7): 18±10 before vs 37±14 pg/mL after [p = 0.002]) compared to atorvastatin treatment (Ang II: 9±4 vs 11±10 pg/mL [p = 0.40]; Ang-(1-7): 24±9 vs 32±8 pg/mL [p = 0.023]). Our study suggests that statin treatment does not elicit major changes in angiotensin II-mediated venoconstriction or in circulating angiotensin II levels whereas angiotensin-(1-7) levels increased modestly. The discrepancy between local vascular and systemic angiotensin II responses might suggest that statin treatment interferes with blood pressure buffering reflexes.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00154024.

A systematic review to investigate whether Angiotensin-(1-7) is a promising therapeutic target in human heart failure

Context. Heart failure (HF) is a common condition causing much morbidity and mortality despite major advances in pharmacological and device therapies. Preclinical data suggest a cardioprotective role of Angiotensin-(1-7) in animal models of HF. Objective. Perform a systematic review on the effects of Angiotensin-(1-7) on humans, focusing on HF. Results. 39 studies were included in the review (4 in human HF and (35) in non-HF patients). There is only one intervention study on 8 patients with human HF, using Angiotensin-(1-7), with forearm blood flow (FBF) as the endpoint. Angiotensin-(1-7) caused no significant effect on FBF in this HF study but caused vasodilation in 3 out of 4 non-HF studies. In one other non-HF study, Angiotensin-(1-7) infusion led to a significant increase in blood pressure in normal men; however, effects were <0.03% that of angiotensin II. Cardioprotective effects seen in non-HF studies include for instance beneficial actions against atherosclerosis and myocardial fibrosis. Conclusions. The main finding of our systematic review is that Angiotensin-(1-7) plays an important cardioprotective role in HF in animals and in patients without heart failure. More research is required to test the hypothesis that Angiotensin-(1-7) benefits patients with heart failure.

Increased circulatory RAS activity can be inhibited by statins in patients with hypercholesterolemia

OBJECTIVE

The objective of this paper is to investigate a profile on circulatory renin-angiotensin system (RAS) activity in hypercholesterolemic (HC) patients treated with statins.

METHODS

Eighteen primary HC patients and 18 sex- and age-matched healthy adults were included in this study as controls. Total cholesterol (TC), triglyceride (TG), LDL-C, blood glucose, angiotensin-converting enzyme (ACE) activity, and angiotensin II (Ang II) levels were measured before and four and eight weeks after beginning statin treatment in the HC group. Similar measurements were taken in the control group at baseline.

RESULTS

At baseline, TC, TG and LDL-C levels, as well as ACE activity and Ang II concentrations, were significantly higher in the HC group than in the control group. Based on the baseline data collection of 36 participants, there were significant positive correlations between ACE activity and TC (r = 0.54) or LDL-C (r = 0.51), and between Ang II level and TC (r = 0.34) or LDL-C (r = 0.27). TC, LDL-C, Ang II (35.46 ± 14.49 vs 71.10 ± 20.47 pg/ml, p < 0.05) levels and ACE activity (108.9 ± 51.9 vs 180.1 ± 71.3 U/L, p < 0.05) were decreased in HC patients eight weeks after starting statin treatment. In HC patients, RAS activity correlated positively with TC and LDL-C levels before and after treatment.

CONCLUSIONS

In HC patients, lowering serum cholesterol with statins is associated with decreased circulatory RAS activity.

Biomarkers: optimizing treatment guidance in heart failure

Heart failure is a frequent and life-threatening syndrome which is not only the result of myocardial injury or hemodynamic overload as commonly perceived, but appears to be the result of an interplay among genetic, neurohormonal, inflammatory, and biochemical factors, collectively referred to as biomarkers. Biomarkers can become risk factors in case their therapeutic modification results in an improvement of clinical outcomes. Among those markers identified in patients with heart failure, a number appears to have direct clinical relevance in aiding diagnosis, risk stratification, monitoring therapy, and treating to targets in order to improve clinical outcomes. These include brain natriuretic peptides (e.g., BNP, NT-proBNP), inflammatory markers (e.g., hsCRP), neurohormones (e.g., aldosterone), cardiorenal markers (e.g., cycstatin C), and novel markers (e.g., galectin-3). While their utility to indicate risk is mostly well established, there are less data to establish that a treatment using biomarkers as a guidance results in better outcomes than a more generalized intensified treatment of patients with heart failure. Future directions may involve larger platforms that facilitate to simultaneously analyze hundreds of biomarkers and may help to tailor heart failure therapy on a single patient basis, considering the specific pathogenesis and prognosis. Also from a therapeutic perspective there are data that a single intervention such as aldosterone blockade may affect multiple biomarkers at the same time. Taken together the data indicate that biomarkers are evolving into a valuable addendum to the diagnostic and therapeutic armamentarium.

ACE2: more of Ang-(1-7) or less Ang II?

PURPOSE OF REVIEW

Previous concepts regarding the pathways involved in the generation of angiotensin II (Ang II) have been challenged by studies showing the existence of a peptide acting as an endogenous antagonist of Ang II. The discovery that angiotensin-(1-7) [Ang-(1-7)] opposes the pressor, proliferative, profibrotic, and prothrombotic actions mediated by Ang II has contributed to the realization that the renin-angiotensin system is composed of two opposing arms: the pressor arm constituted by the enzyme angiotensin-converting enzyme (ACE), Ang II as the product, and the Ang II type 1 (AT1) receptor as the main protein mediating the biological actions of Ang II; the second arm is composed of the monocarboxypeptidase angiotensin-converting enzyme 2 (ACE2), Ang-(1-7) produced through hydrolysis of Ang II, and the Mas receptor as the protein conveying the vasodilator, antiproliferative, antifibrotic, and antithrombotic effects of Ang-(1-7).

RECENT FINDINGS

Experimental and clinical studies demonstrate a role for the Ang-(1-7)/ACE2/Mas axis in the evolution of hypertension, the regulation of renal function, and the progression of renal disease including diabetic nephropathy. Additional evidence suggests that a reduction in the expression and activity of this vasodepressor component may be a critical factor in mediating the progression of cardiovascular disease.

SUMMARY

Further research on the contribution of the Ang-(1-7)/ACE2/Mas axis to cardiovascular pathology will lead to the development of new pharmacological approaches resulting in the design of molecular or genetic means to increase the expression of ACE2, allow for increased tissue levels of Ang-(1-7), or both.

Role of olmesartan in combination therapy in blood pressure control and vascular function

Angiotensin receptor blockers have emerged as a first-line therapy in the management of hypertension and hypertension-related comorbidities. Since national and international guidelines have stressed the need to control blood pressure to <140/90 mmHg in uncomplicated hypertension and <130/80 mmHg in those with associated comorbidities such as diabetes or chronic kidney disease, these goal blood pressures can only be achieved through combination therapy. Of several drugs that can be effectively combined to attain the recommended blood pressure goals, fixed-dose combinations of angiotensin receptor blockers and the calcium channel blocker amlodipine provide additive antihypertensive effects associated with a safe profile and increased adherence to therapy. In this article, we review the evidence regarding the beneficial effects of renin–angiotensin system blockade with olmesartan medoxomil and amlodipine in terms of blood pressure control and improvement of vascular function and target organ damage.

Angiotensin-(1-7) stimulates high atrial pacing-induced ANP secretion via Mas/PI3-kinase/Akt axis and Na+/H+ exchanger

Angiotensin-(1-7) [ANG-(1-7)], one of the bioactive peptides produced in the renin-angiotensin system, plays a pivotal role in cardiovascular physiology by providing a counterbalance to the function of ANG II. Recently, it has been considered as a potential candidate for therapeutic use in the treatment of various types of cardiovascular diseases. The aim of the present study is to explain the modulatory role of ANG-(1-7) in atrial natriuretic peptide (ANP) secretion and investigate the functional relationship between two peptides to induce cardiovascular effects using isolated perfused beating rat atria and a cardiac hypertrophied rat model. ANG-(1-7) (0.01, 0.1, and 1 muM) increased ANP secretion and ANP concentration in a dose-dependent manner at high atrial pacing (6.0 Hz) with increased cGMP production. However, at low atrial pacing (1.2 Hz), ANG-(1-7) did not cause changes in atrial parameters. Pretreatment with an antagonist of the Mas receptor or with inhibitors of phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt), or nitric oxide synthase blocked the augmentation of high atrial pacing-induced ANP secretion by ANG-(1-7). A similar result was observed with the inhibition of the Na(+)/H(+) exchanger-1 and Ca(2+)/calmodulin-dependent kinase II (CaMKII). ANG-(1-7) did not show basal intracellular Ca(2+) signaling in quiescent atrial myocytes. In an in vivo study using an isoproterenol-induced cardiac hypertrophy animal model, an acute infusion of ANG-(1-7) increased the plasma concentration of ANP by twofold without changes in blood pressure and heart rate. A chronic administration of ANG-(1-7) increased the plasma ANP level and attenuated isoproterenol-induced cardiac hypertrophy. The antihypertrophic effect was abrogated by a cotreatment with the natriuretic peptide receptor-A antagonist. These results suggest that 1) ANG-(1-7) increased ANP secretion at high atrial pacing via the Mas/PI3K/Akt pathway and the activation of Na(+)/H(+) exchanger-1 and CaMKII and 2) ANG-(1-7) decreased cardiac hypertrophy which might be mediated by ANP.

Effect of valsartan or olmesartan addition to amlodipine on ankle edema in hypertensive patients

INTRODUCTION

The objective of this study was to compare the effect on ankle edema of adding valsartan (V) or olmesartan (O) to amlodipine (A) in the treatment of hypertension.

METHODS

After a 4-week placebo period, 74 adult outpatients with essential hypertension (diastolic blood pressure [DBP] >90 and <110 mmHg, and systolic blood pressure [SBP] >140 mmHg) were treated with A 10 mg once daily for 4 weeks. Thereafter, nonresponder patients (DBP >90 mmHg and/or SBP >140 mmHg; n=51) were randomized to receive additional V 160 mg once daily or O 20 mg once daily for 8 weeks in two crossover periods, each separated by a 4-week placebo period. Clinic blood pressure (BP), heart rate, and ankle/foot volume (AFV) were evaluated and blood samples were drawn to evaluate plasma norepinephrine (NE) levels.

RESULTS

Both V/A and O/A induced a greater SBP/DBP reduction than A monotherapy (-26.4/-20.8 mmHg and -24.4/-19.1 mmHg, respectively; all P<0.001 vs. baseline and P<0.01 vs. A). A monotherapy increased AFV by 24%, P<0.001 vs. baseline, while the addition of either V or A reduced such increases. However, with V/A the AFV increase (+9.7%, P<0.05 vs. baseline, P<0.01 vs. A) was lower than with O/A (+16.7%, P<0.01 vs. baseline, P<0.05 vs. A); the difference between the two combinations was significant. Plasma NE levels were significantly increased by A (+44.6%) and values did not change with the addition of V (+35.2%) or O (+33.7%). Plasma active renin (PAR) was unchanged by A but increased by V/A (+214.4%, P<0.05 vs. baseline) and further by O/A (+325.6%, P<0.01 vs. baseline; difference between the 2 combinations: P<0.05). An inverse correlation was found between the AFV decrease and PAR increase (r=-0.31, P<0.05).

CONCLUSION

Adding V or O to A reduced ankle edema, but this effect was more pronounced with V. The greater degree of renin-angiotensin system activation observed with Ocould be related to such a difference.

Enalapril, irbesartan, and angiotensin-(1-7) prevent atrial tachycardia-induced ionic remodeling

BACKGROUND

Atrial fibrillation (AF) is associated with activation of the renin-angiotensin system (RAS) in the atria. Angiotensin-(1-7) [Ang-(1-7)] is a biologically active component of the RAS, it not only counterbalances the actions of angiotensin II (Ang II) but also is a potential inhibitor of angiotensin-converting enzyme (ACE). The purpose of this study was to investigate the effects of the ACE inhibitor enalapril, the angiotensin-receptor blocker (ARB) irbesartan, and Ang-(1-7) on the chronic atrial ionic remodeling.

METHODS

Thirty dogs were assigned to sham, paced, paced + enalapril, paced + irbesartan or paced + Ang-(1-7) group, 6 dogs in each group. Rapid atrial pacing at 500 beats per minute was maintained for 14 days, but dogs in sham group were instrumented without pacing. During the pacing, enalapril (2 mg · Kg(-1) · d(-1)) and irbesartan (60 mg · Kg(-1) · d(-1)) were given orally and Ang-(1-7) (6 μg · Kg(-1) · h(-1)) was given intravenously. Whole-cell patch-clamp technique was used to record atrial ionic currents and action potential duration (APD). And RT-PCR was applied to assess atrial mRNA expression of I(TO) Kv4.3 and I(CaL)α1C subunits.

RESULTS

Compared with sham, rapid pacing shortened APD90 (P < 0.05) of atrial myocytes, and decreased APD90 rate adaptation (P<0.05). APD90 changes were prevented by irbesartan and Ang-(1-7), but not enalapril. In atria from paced group, the densities and gene expression of I(TO) and I(CaL) were reduced (P < 0.01 vs. sham). Enalapril increased the density and gene expression of I(TO) compared with sham (P < 0.01), Ang-(1-7) prevented the decrease of I(TO) and I(CaL) (P < 0.05 vs. control) and Kv4.3 mRNA expression (P < 0.01 vs. control). Irbesartan had no effect on I(TO) and I(CaL) densities or mRNA expression.

CONCLUSIONS

These results suggest that enalapril, irbesartan, and Ang-(1-7) have differing influences on atrial tachycardia-induced atrial ionic remodeling.

Effect of angiotensin receptor blockade on endothelial function: focus on olmesartan medoxomil

Endothelial dysfunction is the common link between cardiovascular disease risk factors and the earliest event in the cascade of incidents that results in target organ damage. Angiotensin II, the terminal pressor effector arm of the renin-angiotensin-aldosterone system, increases blood pressure (BP) by vasoconstriction and sodium and fluid retention, and has a pro-oxidative action that induces endothelial dysfunction and contributes to vascular remodeling. Angiotensin receptor blockers (ARBs) reduce BP and morbidity and mortality in patients with hypertension, ventricular hypertrophy, diabetes mellitus, and renal disease. Olmesartan medoxomil is a long-acting, well-tolerated, effective ARB that prevents or reverses endothelial dysfunction in animal models of atherosclerosis, hypertension, diabetes, nephropathy, and retinopathy. Olmesartan medoxomil, a prodrug of olmesartan approved for the treatment of hypertension, has been shown to ameliorate endothelial dysfunction in patients with hypertension or diabetes. In randomized studies, the drug reduces vascular inflammation and the volume of large atherosclerotic plaques, increases the number of regenerative endothelial progenitor cells in the peripheral circulation, improves endothelium-dependent relaxation, and restores the normal resistance vessel morphology. Importantly, the impact of olmesartan medoxomil on endothelial dysfunction is thought to be independent of BP lowering.

ACE-inhibitor, AT1-receptor-antagonist, or both? A clinical pharmacologist's perspective after publication of the results of ONTARGET

Clinical Pharmacology is commonly accepted to be a bridging discipline between basic science observations and clinical practice. Today, it should be a major task of the clinical pharmacologist in academia to provide support in the interpretation of preclinical and clinical study data, to develop evidence-based treatment guidelines and to serve as drug expert supporting all disciplines of clinical medicine with specific pharmacological and therapeutic knowledge. The results of the ONTARGET-trial confront both researchers and clinicians with the unexpected truth that AT(1)-receptor-blockade with an angiotensin-receptor-blocker (ARB) does not seem to have superior therapeutic benefit compared with an ACE-inhibitor (ACE-I) at reducing fatal and nonfatal cardiovascular events. The combination of the two drugs was associated with more adverse events without an increase in benefit. Therefore, the crucial question 'ACE-I, ARB, or both?' requires a new and critical appraisal depending on the medical indication for which these renin-angiotensin-system (RAS)-inhibitors are used: In a population of high-risk patients suffering from cardiovascular disease or diabetes mellitus, the evidence to favor an ARB over an ACE-I is still limited after ONTARGET and because of the higher costs for ARBs one can rather support the old therapeutic advice that ARBs are equally effective as ACE-Is and therefore therapeutic alternatives for patients with ACE-I intolerance. With respect to a very moderate additive BP-lowering effect of dual therapy with an ACE-I and an ARB seen in metaanalysis which was not even clearly attributable to dual RAS-inhibition and the increased adverse event rate in the combination treatment group of ONTARGET, this regimen seems not to be recommendable for the treatment of hypertension. Dual-RAS-blockade using an ACE-I-ARB-combination is an effective therapy to treat proteinuria and might be of therapeutic benefit especially in diabetic patients without concomitant diseases. There may be a therapeutic rationale to prefer ARBs over ACE-Is in well-selected patients with congestive heart failure (CHF) because a considerable amount of angiotensin II (Ang II) is produced independent of angiotensin-conversion-enzyme (ACE) in the failing heart and is therapeutically unaffected by ACE-I treatment. The results of the Val-HeFt and the CHARM-added-study revealed additive effects of an ARB on heart failure related morbidity and mortality when added to existing therapy with an ACE-I suggesting a role for ACE-I-ARB-combination treatment in well selected heart failure patients. Independent of the medical indication for its use, the concept of dual RAS-blockade with an ARB-ACE-I-combination should clinically be used with caution and a close monitoring of potassium levels and kidney function. Although the results of ONTARGET revealed equity of ramipril and telmisartan at reducing fatal and nonfatal cardiovascular events, we should not forget that pharmacologically not all ARBs are the same and the question if the study results of ONTARGET with telmisartan are transferable to the complete class of ARBs still merits further investigation.

New angiotensins

Accumulation of a large body of evidence during the past two decades testifies to the complexity of the renin–angiotensin system (RAS). The incorporation of novel enzymatic pathways, resulting peptides, and their corresponding receptors into the biochemical cascade of the RAS provides a better understanding of its role in the regulation of cardiovascular and renal function. Hence, in recent years, it became apparent that the balance between the two opposing effector peptides, angiotensin II and angiotensin-(1-7), may have a pivotal role in determining different cardiovascular pathophysiologies. Furthermore, our recent studies provide evidence for the functional relevance of a newly discovered rat peptide, containing two additional amino acid residues compared to angiotensin I, first defined as proangiotensin-12 [angiotensin-(1-12)]. This review focuses on angiotensin-(1-7) and its important contribution to cardiovascular function and growth, while introducing angiotensin-(1-12) as a potential novel angiotensin precursor.

Effect of angiotensin receptor blockade on central haemodynamics in essential hypertension: results of a randomised trial

Objective. Angiotensin-converting enzyme (ACE) inhibitors have been shown to lower central augmentation index (cAI), an index of arterial wave reflection, more than β-blockers. We tested whether this is also true for long-term treatment with an angiotensin receptor blocker (ARB).

Methods. One-hundred and fifty-six subjects with essential hypertension were randomised to treatment with either irbesartan or atenolol. cAI and central blood pressure (BP) were determined by pulse wave analysis from the radial and the carotid artery after six and after 18 months treatment.

Results. Peripheral and central systolic and diastolic BP were reduced to a similar extent A in the two groups. cAI was reduced with irbesartan, but increased with atenolol (derived from the carotid artery: -6±10 vs. -4±12% after six months, p<0.001; —4±12 vs. +1±11% after 18 months; p=0.011). Furthermore, central to peripheral pulse pressure (PP) amplification was unaffected by treatment with irbesartan, but decreased with atenolol.

Conclusions. Although treatment with irbesartan and atenolol similarly decreased peripheral and central BP, only treatment with irbesartan had beneficial effects on arterial wave reflection and preserved PP amplification. These haemodynamic effects may at least partly explain the reported differential effects of ARB versus β-blocker treatment on cardiovascular mortality in patients with essential hypertension.

Comparison of Selective AT1-Receptor Blockade Versus ACE Inhibition for Restenosis Prophylaxis in Patients With Peripheral Occlusive Arterial Disease After Stent Angioplasty: A Randomized, Controlled, Proof-of-Concept Study

Different components of the renin-angiotensin system (RAS) have been demonstrated in atherosclerotic plaques. However, the involvement of the RAS in the complex process of in-stent restenosis is not yet clear. In this prospective, randomized, double-blind, controlled proof-of-concept study, we compared the 2 different pharmacological approaches, selective AT1-receptor-blockade with candesartan vs ACE inhibition with quinapril to reduce in-stent restenosis after stent angioplasty of the superficial femoral artery. Twenty-two hypertensive patients with stage IIb peripheral occlusive arterial disease and severe claudication who had been successfully treated with percutaneous transluminal angioplasty (PTA) and stent implantation were randomly assigned to receive daily doses of either candesartan (32 mg) or quinapril (20 mg). Primary end point was restenosis 6 months after intervention, assessed by angiography. Secondary end points were pain-free walking distance, determined by treadmill ergometry; determination of crurobrachial indices; and intima-media thickness (IMT). At 6 months, the rate of restenosis on angiography was 34% in the candesartan group and 71% in the quinapril group (P = .043). Relevant restenosis was found in 3 patients (27%) in the candesartan group and in 7 patients (64%) in the quinapril group. Patients in the candesartan group were able to walk farther on a treadmill (increase: 135 m ± 20 m) compared with patients in the quinapril group (increase: 83 m ± 21 m). The IMT at the stent edge was not significantly different in the 2 groups (candesartan: 1.9 mm ± 0.5 mm; quinapril: 2.0 mm ± 0.3 mm). This study revealed significant benefit of a pharmacological restenosis regimen using the AT1-receptor antagonist candesartan in patients with severe atherosclerosis after superficial femoral artery stenting compared with treatment with the ACE inhibitor quinapril. Further prospective studies in patients are required to confirm these results.

Angiotensin-(1-7): pharmacology and new perspectives in cardiovascular treatments

Many advances have been made in the cardiovascular field in the last several decades. Among them is the progress completed to date on the heptapeptide member of the renin-angiotensin system (RAS), angiotensin-(1-7) [Ang-(1-7)]. The peptide's beneficial actions against pathophysiological processes, such as cardiac arrhythmia, heart failure, hypertension, renal disease, preeclampsia, and even cancer are continuously being uncovered. This review encompasses the pharmacology of Ang-(1-7) and expounds upon the peptide's potential as a therapeutic agent against pathological processes both within and outside the cardiovascular continuum.