Role of endogenous GLP-1 on arterial stiffness and renal haemodynamics following bariatric surgery

BACKGROUND

Cardiovascular trials have revealed the positive impact of GLP-1 receptor agonists (GLP-1 RAs) on cardiovascular outcomes in type 2 diabetes (T2D). However, the specific effects of endogenous GLP-1 on arterial stiffness and renal function remain understudied. This study aimed to explore the influence of endogenous GLP-1 response post-bariatric surgery on arterial stiffness and renal haemodynamic.

METHODS

Thirty individuals with morbid obesity and without T2D, scheduled for Roux-en-Y Gastric Bypass (RYGB), were included. Clinical parameters, 3-hour oral glucose tolerance test (OGTT) with serial sampling for glycaemia, GLP-1 and insulin, carotid-femoral pulse wave velocity (cf-PWV), carotid distensibility coefficient (carotid-DC) and renal resistive index (RRI) measurements were conducted pre-surgery and 1-year post-surgery. Participants were categorized into high-response and low-response groups based on their post-surgery increase in GLP-1 (median increase of 104% and 1%, respectively, pre- vs. post-surgery).

RESULTS

Post-surgery, high-response group demonstrated a greater reduction in cf-PWV (p = .033) and a greater increase (p = .043) in carotid DC compared to low-response group. These enhancements were observed independently of weight loss or blood pressure changes. High-response group exhibited a reduction in RRI (p = .034), although this association was influenced by improvement in pulse pressure. Finally, a multivariate stepwise regression analysis indicated that the percentage increase of GLP1, Δ-GLP1(AUC)%, was the best predictor of percentage decrease in cf-PWV (p = .014).

CONCLUSIONS

Elevated endogenous GLP-1 response following RYGB was associated with improved arterial stiffness and renal resistances, suggesting potential cardio-renal benefits. The findings underscore the potential role of endogenous GLP-1 in influencing vascular and renal haemodynamics independent of traditional weight loss.

Renin inhibitors versus angiotensin converting enzyme (ACE) inhibitors for primary hypertension

BACKGROUND

Renin inhibitors (RIs) reduce blood pressure more than placebo, with the magnitude of this effect thought to be similar to that for angiotensin converting enzyme (ACE) inhibitors. However, a drug's efficacy in lowering blood pressure cannot be considered as a definitive indicator of its effectiveness in reducing mortality and morbidity. The effectiveness and safety of RIs compared to ACE inhibitors in treating hypertension is unknown.

OBJECTIVES

To evaluate the benefits and harms of renin inhibitors compared to ACE inhibitors in people with primary hypertension.

SEARCH METHODS

The Cochrane Hypertension Group Information Specialist searched the following databases for randomized controlled trials up to August 2020: the Cochrane Hypertension Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (from 1946), Embase (from 1974), the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also contacted authors of relevant papers about further published and unpublished work. The searches had no language restrictions.

SELECTION CRITERIA

We included randomized, active-controlled, double-blinded studies (RCTs) with at least four weeks follow-up in people with primary hypertension, which compared renin inhibitors with ACE inhibitors and reported morbidity, mortality, adverse events or blood pressure outcomes. We excluded people with proven secondary hypertension.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected the included trials, evaluated the risks of bias and entered the data for analysis.

MAIN RESULTS

We include 11 RCTs involving 13,627 participants, with a mean baseline age from 51.5 to 74.2 years. Follow-up duration ranged from four weeks to 36.6 months. There was no difference between RIs and ACE inhibitors for the outcomes: all-cause mortality: risk ratio (RR) 1.05, 95% confidence interval (CI) 0.93 to 1.18; 5 RCTs, 5962 participants; low-certainty evidence; total myocardial infarction: RR 0.86, 95% CI 0.22 to 3.39; 2 RCTs, 957 participants; very low-certainty evidence; adverse events: RR 0.98, 95% CI 0.93 to 1.03; 10 RTCs, 6007 participants;  moderate-certainty evidence; serious adverse events: RR 1.21, 95% CI 0.89 to 1.64; 10 RTCs, 6007 participants; low-certainty evidence; and withdrawal due to adverse effects: RR 0.85, 95% CI 0.68 to 1.06; 10 RTCs, 6008 participants; low-certainty evidence. No data were available for total cardiovascular events, heart failure, stroke, end-stage renal disease or change in heart rate. Low-certainty evidence suggested that RIs reduced systolic blood pressure: mean difference (MD) -1.72, 95% CI -2.47 to -0.97; 9 RCTs, 5001 participants;  and diastolic blood pressure: MD -1.18, 95% CI -1.65 to -0.72; 9 RCTs, 5001 participants,  to a greater extent than ACE inhibitors, but we judged this to be more likely due to bias than a true effect.  AUTHORS' CONCLUSIONS: For the treatment of hypertension, we have low certainty that renin inhibitors (RI) and angiotensin converting enzyme (ACE) inhibitors do not differ for all-cause mortality and myocardial infarction. We have low to moderate certainty that they do not differ for adverse events. Small reductions in blood pressure with renin inhibitors compared to ACE inhibitors are of low certainty.  More independent, large, long-term trials are needed to compare RIs with ACE inhibitors, particularly assessing morbidity and mortality outcomes, but also on blood pressure-lowering effect.

Effect of direct renin inhibition on vascular function after long-term treatment with aliskiren in hypertensive and diabetic patients

OBJECTIVE

We tested the hypothesis that chronic treatment with the direct renin inhibitor aliskiren improves vascular function in resistance and conduit arteries of type two diabetic and hypertensive patients.

METHOD

Sixteen patients with mild essential hypertension and with a previous diagnosis of noninsulin-dependent diabetes mellitus were included in the study. Patients were then randomized to aliskiren (150 mg once daily, n = 9), or ramipril (5 mg once daily, n = 7). Each patient underwent a biopsy of the subcutaneous tissue and small arteries were dissected and mounted on a pressurized micromyograph to evaluate endothelium dependent vasorelaxation in response to acetylcholine ± N omega-nitro-L-arginine methyl ester hydrochloride in vessels precontracted with norepinephrine. Endothelial function has been quantified also in large conduit arteries by flow-mediated dilation.

RESULTS

A similar office blood pressure-lowering effect was observed with the two drugs, although changes in DBP were not statistically significant in the ramipril group. Aliskiren significantly improved endothelium-dependent relaxation in subcutaneous resistance arteries, as well as increased flow-mediated dilation in conduit arteries, whereas the effects induced by ramipril did not reach statistical significance. Only aliskiren significantly increased the expression of p1177-endothelial nitric oxide synthase in the endothelium. Both aliskiren and ramipril had a negligible effect on markers of oxidative stress.

CONCLUSION

Aliskiren restored endothelial function and induced a more prompt peripheral vasodilation in hypertensive and diabetic patients possibly through the increased production of nitric oxide via the enhanced expression and function of the active phosphorylated form of endothelial nitric oxide synthase.

Effects of Angiotensin-Converting Enzyme Inhibitors on Arterial Stiffness: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

To determine the effects of ACEIs on arterial stiffness, a meta-analysis of randomized controlled trials was conducted. Relevant articles that investigated the effects of ACEIs on arterial stiffness from PubMed, Embase, and the Cochrane library from inception to September 2018 were systematically retrieved. The investigated outcomes included brachial-ankle pulse wave velocity (ba-PWV) and carotid-femoral PWV (cf-PWV) by using weighted mean differences (WMDs) and 95% confidence intervals (CIs) with the random-effects model. A total of 17 RCTs including 1,458 individuals were included. The summary results indicated no significant differences between ACEIs and control for ba-PWV and cf-PWV. Also, no significant differences between ACEI and control for ba-PWV and cf-PWV were observed in hypertensive patients, while the therapeutic effects of ACEI versus placebo showed statistically significant difference. Moreover, subgroup analysis indicated that the levels of ba-PWV were significantly associated if the study was conducted in Western countries, mean age <60.0 years, percentage male ≥60.0%, compared with ARBs, baseline PWV <10.0, and high-quality study. Furthermore, the significant levels of cf-PWV in patients who received ACEIs were observed when percentage male was ≥60.0% and the studies were of high-quality. Finally, no significant differences were observed between ACEIs and other antihypertensive drugs regarding the changes of systolic blood pressure (SBP) and diastolic blood pressure (DBP). The overall analysis suggested no significant differences between ACEIs and other antihypertensive drugs for ba-PWV and cf-PWV levels, whereas ACEIs versus placebo showed lower levels of ba-PWV and cf-PWV.

Central blood pressure for the management of hypertension: Is it a practical clinical tool in current practice?

Since noninvasive central blood pressure (BP) measuring devices are readily available, central BP has gained growing attention regarding its clinical application in the management of hypertension. The disagreement between central and peripheral BP has long been recognized. Some previous studies showed that noninvasive central BP may be better than the conventional brachial BP in association with target organ damages and long-term cardiovascular outcomes. Recent studies further suggest that the central BP strategy for confirming a diagnosis of hypertension may be more cost-effective than the conventional strategy, and guidance of hypertension management with central BP may result in less use of medications to achieve BP control. Despite the use of central BP being promising, more randomized controlled studies comparing central BP-guided therapeutic strategies with conventional care for cardiovascular events reduction are required because noninvasive central and brachial BP measures are conveniently available. In this brief review, the rationale supporting the utility of central BP in clinical practice and relating challenges are summarized.

The use of aliskiren as an antifibrotic drug in experimental models: A systematic review

Aliskiren is an oral antihypertensive medication that acts by directly inhibiting renin. High levels of circulating renin and prorenin activate the pathological signaling pathway of fibrosis. This drug also reduces oxidative stress. Thus, the aim of this systematic review is to analyze experimental studies that show the actions of aliskiren on fibrosis. PubMed and LILACS databases were consulted using the keywords aliskiren and fibrosis within the period between 2005 and 2017. Fifty-three articles were analyzed. In the heart, aliskiren attenuated remodeling, hypertrophy, inflammatory cytokines, collagen deposition, and oxidative stress. In the kidneys, there was a reduction in interstitial fibrosis, the infiltration of inflammatory cells, apoptosis, proteinuria, and in the recruitment of macrophages. In diabetic models, an improvement in the albumin/creatinine relationship and in the insulin pathway in skeletal muscles was observed; aliskiren was beneficial to pancreatic function and glucose tolerance. In the liver, aliskiren reduced fibrosis, steatosis, inflammatory cytokines, and collagen deposition. In the lung and peritoneal tissues, there was a reduction in fibrosis. Many studies have reported on the beneficial effects of aliskiren on endothelial function and arterial rigidity. A reduction in fibrosis in different organs is cited by many authors, which complies with the results found in this review. However, studies diverge on the use of the drug in diabetic patients. Aliskiren has antifibrotic potential in several experimental models, interfering with the levels of fibrogenic cytokines and oxidative stress. Therefore, its use in diseases in which fibrosis plays an important pathophysiological role is suggested.

Impact of antihypertensive agents on arterial stiffness in hypertensive patients

AIMS

The present network meta-analysis was performed to comprehensively compare the ability of different types of antihypertensive agents to ameliorate arterial stiffness in hypertensive patients.

METHODS AND RESULTS

To conduct this network meta-analysis, we searched PubMed, the Embase database, and the https://clinicaltrials.gov/ website for all relevant articles concerning clinical trials on hypertension therapy. The last search date was 10 August 2017. As a result, 28 eligible articles were enrolled in our meta-analysis. According to the included studies, there was no significant difference in pulse wave velocity (PWV) between these treatments. The eight types of antihypertension agents outperformed placebo in controlling systolic blood pressure (SBP). Angiotensin-converting enzyme inhibitor (ACEI) outperformed angiotensin II receptor blocker (ARB) in SBP; and angiotensin receptor-neprilysin inhibitor (ARNI) outperformed diuretic (D)in SBP.

CONCLUSIONS

This study found that the eight antihypertensive agents show obvious effect on reducing SBP other than arterial stiffness.

The Role of Renin-Angiotensin-Aldosterone System and Its New Components in Arterial Stiffness and Vascular Aging

Many cardiovascular diseases present renin-angiotensin-aldosterone system (RAAS) hyperactivity as an important pathophysiological mechanism to be target in the therapeutic approaches. Moreover, arterial stiffness is currently considered as a new independent risk factor for cardiovascular disease in different clinical conditions, including hypertension and chronic kidney disease. In fact, excessive stimulation of angiotensin type 1 (AT1) receptors, as well as mineralocorticoid receptors, results in cellular growth, oxidative stress and vascular inflammation, which may lead to arterial stiffness and accelerate the process of vascular aging. In the last decades, a vasoprotective axis of the RAAS has been discovered, and now it is well established that new components with antioxidant and anti-inflammatory properties play important roles promoting vasodilation, natriuresis and reducing collagen deposition, thus attenuating arterial stiffness and improving endothelial function. In this review, we will focus on these pathophysiological mechanisms and the relevance of RAAS inhibition by different strategies to increase arterial compliance and to decelerate vascular aging.

Comparison of the Effect of Aliskiren Versus Negative Controls on Aortic Stiffness in Patients With Marfan Syndrome Under Treatment With Atenolol

INTRODUCTION AND OBJECTIVES

The aim of this study was to evaluate the effect of aliskiren on aortic stiffness in patients with Marfan syndrome (MS).

METHODS

Twenty-eight MS patients (mean age ± standard deviation: 32.6 ± 10.6 years) were recruited from November 2009 to October 2014. All patients were receiving atenolol as standard beta-blocker therapy. A prospective randomization process was performed to assign participants to either aliskiren treatment (150-300mg orally per day) or no aliskiren treatment (negative control) in an open-label design. Central aortic distensibility and central pulsed wave velocity (PWV) by magnetic resonance imaging (MRI), peripheral PWV, central aortic blood pressure and augmentation index by peripheral tonometry, and aortic dilatation by echocardiography were examined initially and after 24 weeks. The primary endpoint was central aortic distensibility by MRI.

RESULTS

In analyses of differences between baseline and 24 weeks for the aliskiren treatment group vs the negative control group, central distensibility (overall; P = .26) and central PWV (0.2 ± 0.9 vs 0.03 ± 0.7 [m/s]; P = .79) by MRI were not significantly different. Central systolic aortic blood pressure tended to be lower by 14mmHg in patients in the aliskiren treatment group than in the control group (P = .09). A significant decrease in peripheral PWV (brachial-ankle PWV) in the aliskiren treatment group (-1.6 m/s) compared with the control group (+0.28 m/s) was noted (P = .005).

CONCLUSIONS

Among patients with MS, the addition of aliskiren to beta-blocker treatment did not significantly improve central aortic stiffness during a 24-week period.

The acute effect of black tea consumption on resistance artery endothelial function in healthy subjects. A randomized controlled trial

BACKGROUND & AIMS

Black tea is a main source of flavonoids in the Western diet and has been associated with reduced risk for cardiovascular disease, possibly through lowering blood pressure. These effects may be mediated through improving endothelial function of resistance arteries. The aim of this study was therefore to examine the acute impact of black tea on forearm resistance artery endothelial function in healthy, normotensive middle-aged subjects.

METHODS

Twenty middle-aged men and women (age-range 45-75 years) were recruited into a double-blind, randomized, placebo-controlled crossover intervention study. Forearm resistance artery blood flow (FBF, measured using venous occlusion plethysmography) in response to incremental doses of acetylcholine, sodium nitroprusside and L-N^G-monomethyl arginine were determined 2 h after consumption of either black tea containing ∼400 mg flavonoids (equivalent to 2-3 cups of tea) or a taste- and color-matched placebo.

RESULTS

The mean FBF-response to acetylcholine after tea consumption was 23% higher compared to the response after placebo (95% CI: -20%, +88%), but this difference did not reach statistical significance (P = 0.32). No significant differences in the FBF-responses to sodium nitroprusside and L-N^G-monomethyl arginine were found between the tea and placebo interventions (P = 0.96 and 0.74, respectively). Correcting FBF for changes in blood pressure did not alter the outcomes.

CONCLUSIONS

We found no evidence that acute intake of black tea significantly altered endothelium-dependent vasodilation of forearm resistance arteries in healthy middle-aged subjects. Interventions with a longer duration of tea ingestion are required to further explore the (long-term) impact of tea flavonoids on blood pressure regulatory mechanisms. This trial was registered at clinicaltrials.gov as NCT02328339.

Endothelial dysfunction in human essential hypertension

Although the endothelium has a number of important functions, the term endothelial dysfunction is commonly used to describe impairment in its vasodilatory capacity. It is increasingly recognized that this is related to hypertension, although whether it predates essential hypertension or is a consequence of it is still unknown. In this review, we explore the mechanisms of endothelial dysfunction in essential hypertension, its prognostic significance and methods of pharmacological reversal.

Long-term effects of a renin inhibitor versus a thiazide diuretic on arterial stiffness and left ventricular diastolic function in elderly hypertensive patients

Arterial stiffness and cardiac function are important predictors of cardiovascular events in patients with hypertension, even with adequate blood pressure (BP) control. We evaluated whether a direct renin inhibitor, aliskiren, reduces arterial stiffness and modulates left ventricular function compared with a diuretic, hydrochlorothiazide, in elderly hypertensive patients. Twenty-one hypertensive patients [67 ± 14 (SD) yr] were randomly assigned to receive 6-mo aliskiren (n = 11) or hydrochlorothiazide (n = 10)-based therapy. We assessed β-stiffness of the local arteries, arterial elastance (E_a), and echocardiographic variables, including early (E) and late (A) mitral inflow velocity, deceleration time of E, early (E') and late (A') diastolic mitral annular velocity, and left ventricular end-systolic elastance (E_es) before and after treatment. BP decreased similarly (P < 0.001) after both therapies. β-Stiffness of the carotid artery decreased after aliskiren but increased after hydrochlorothiazide treatment (aliskiren: 6.42 ± 2.34 pre vs. 5.07 ± 1.29 post; hydrochlorothiazide: 5.05 ± 1.78 vs. 7.25 ± 2.68, P = 0.001 for interaction). β-Stiffness of the femoral and radial arteries were not different after either treatment. Different from aliskiren, E decreased (73 ± 16 vs. 67 ± 14 cm/s, P = 0.026), and the deceleration time was prolonged (218 ± 40 vs. 236 ± 35 ms, P = 0.032) after hydrochlorothiazide therapy, whereas the E/A, and E' remained unchanged after both treatments. E_a and E_es decreased after aliskiren therapy (both P < 0.05), whereas the E_a/E_es (ventricular-arterial coupling) was maintained after both treatments. Thus, aliskiren decreased the stiffness of carotid artery and left ventricular end-systolic elastance with maintenance of ventricular-arterial coupling without any effects on diastolic filling, while hydrochlorothiazide increased carotid arterial stiffness and slowed early diastolic filling in elderly hypertensive patients.

Endothelial dysfunction and vascular disease - a 30th anniversary update

The endothelium can evoke relaxations of the underlying vascular smooth muscle, by releasing vasodilator substances. The best-characterized endothelium-derived relaxing factor (EDRF) is nitric oxide (NO) which activates soluble guanylyl cyclase in the vascular smooth muscle cells, with the production of cyclic guanosine monophosphate (cGMP) initiating relaxation. The endothelial cells also evoke hyperpolarization of the cell membrane of vascular smooth muscle (endothelium-dependent hyperpolarizations, EDH-mediated responses). As regards the latter, hydrogen peroxide (H₂ O₂ ) now appears to play a dominant role. Endothelium-dependent relaxations involve both pertussis toxin-sensitive G_i (e.g. responses to α₂ -adrenergic agonists, serotonin, and thrombin) and pertussis toxin-insensitive G_q (e.g. adenosine diphosphate and bradykinin) coupling proteins. New stimulators (e.g. insulin, adiponectin) of the release of EDRFs have emerged. In recent years, evidence has also accumulated, confirming that the release of NO by the endothelial cell can chronically be upregulated (e.g. by oestrogens, exercise and dietary factors) and downregulated (e.g. oxidative stress, smoking, pollution and oxidized low-density lipoproteins) and that it is reduced with ageing and in the course of vascular disease (e.g. diabetes and hypertension). Arteries covered with regenerated endothelium (e.g. following angioplasty) selectively lose the pertussis toxin-sensitive pathway for NO release which favours vasospasm, thrombosis, penetration of macrophages, cellular growth and the inflammatory reaction leading to atherosclerosis. In addition to the release of NO (and EDH, in particular those due to H₂ O₂ ), endothelial cells also can evoke contraction of the underlying vascular smooth muscle cells by releasing endothelium-derived contracting factors. Recent evidence confirms that most endothelium-dependent acute increases in contractile force are due to the formation of vasoconstrictor prostanoids (endoperoxides and prostacyclin) which activate TP receptors of the vascular smooth muscle cells and that prostacyclin plays a key role in such responses. Endothelium-dependent contractions are exacerbated when the production of nitric oxide is impaired (e.g. by oxidative stress, ageing, spontaneous hypertension and diabetes). They contribute to the blunting of endothelium-dependent vasodilatations in aged subjects and essential hypertensive and diabetic patients. In addition, recent data confirm that the release of endothelin-1 can contribute to endothelial dysfunction and that the peptide appears to be an important contributor to vascular dysfunction. Finally, it has become clear that nitric oxide itself, under certain conditions (e.g. hypoxia), can cause biased activation of soluble guanylyl cyclase leading to the production of cyclic inosine monophosphate (cIMP) rather than cGMP and hence causes contraction rather than relaxation of the underlying vascular smooth muscle.

Aliskiren attenuates bleomycin-induced pulmonary fibrosis in rats: focus on oxidative stress, advanced glycation end products, and matrix metalloproteinase-9

Pulmonary fibrosis is a progressive lung disorder with high mortality rate and limited successful treatment. This study was designed to assess the potential anti-oxidant and anti-fibrotic effects of aliskiren (Alsk) during bleomycin (BLM)-induced pulmonary fibrosis. Male Wistar rats were used as control untreated or treated with the following: a single dose of 2.5 mg/kg of BLM endotracheally and BLM and Alsk (either low dose 30 mg/kg/day or high dose 60 mg/kg/day), and another group was given Alsk 60 mg/kg/day alone. Alsk was given by gavage. Alsk anti-oxidant and anti-fibrotic effects were assessed. BLM significantly increased relative lung weight and the levels of lactate dehydrogenase and total and differential leucocytic count in bronchoalveolar lavage that was significantly ameliorated by high-dose Alsk treatment. As markers of oxidative stress, BLM caused a significant increase in the levels of lipid peroxides and nitric oxide accompanied with a significant decrease of superoxide dismutase and glutathione transferase enzymes. High-dose Alsk treatment restored these markers toward normal values. Alsk counteracted the overexpression of advanced glycation end products, matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of metalloproteinases-1 in lung tissue induced by BLM. Fibrosis assessed by measuring hydroxyproline content, which markedly increased in the BLM group, was also significantly reduced by Alsk. These were confirmed by histopathological and immunohistochemical examination which revealed that Alsk attenuates signs of pulmonary fibrosis and decreased the overexpressed MMP-9 and transforming growth factor β1. Collectively, these findings indicate that Alsk has a potential anti-fibrotic effect beside its anti-oxidant activity.

Impact of Antihypertensive Agents on Central Systolic Blood Pressure and Augmentation Index: A Meta-Analysis

BACKGROUND

New evidence suggests that central systolic blood pressure (cSBP) and augmentation index (AI) are superior predictors of adverse cardiovascular outcomes compared to peripheral systolic BP (pSBP). We performed a meta-analysis assessing the impact of antihypertensives on cSBP and AI.

METHODS

PubMed, Cochrane Library, and CINAHL were searched until September 2014 to identify eligible articles. A DerSimonian and Laird random-effects model was used to calculate the weighted mean difference (WMD) and its 95% confidence interval (CI). Fifty-two and 58 studies incorporating 4,381 and 3,716 unique subjects were included for cSBP and AI analysis, respectively.

RESULTS

Overall, antihypertensives reduced pSBP more than cSBP (WMD 2.52 mm Hg, 95% CI 1.35 to 3.69; I (2) = 21.9%). β-Blockers (BBs) posed a significantly greater reduction in pSBP as compared to cSBP (WMD 5.19 mm Hg, 95% CI 3.21 to 7.18). α-Blockers, angiotensin converting enzyme inhibitors, angiotensin II receptor blockers, calcium channel blockers, diuretics, renin-angiotensin aldosterone system inhibitors and nicorandil reduced cSBP and pSBP in a similar manner. The overall reduction in AI from baseline was 3.09% (95% CI 2.28 to 3.90; I (2) = 84.5%). A significant reduction in AI was seen with angiotensin converting enzyme inhibitors, angiotensin II receptor blockers, calcium channel blockers, diuretics, renin-angiotensin aldosterone system inhibitors, BBs, α-blockers (ABs), nicorandil, and moxonidine reduced AI nonsignificantly.

CONCLUSIONS

BBs are not as beneficial as the other antihypertensives in reducing cSBP and AI.

Effects of baroreflex activation therapy on arterial stiffness and central hemodynamics in patients with resistant hypertension

BACKGROUND

High central blood pressure, augmentation index and pulse wave velocity are independent cardiovascular risk factors. Little is known of the effect of baroreflex activation therapy on central hemodynamics.

METHOD

In this prospective clinical trial, radial artery applanation tonometry and pulse wave analysis were used to derive central aortic pressure and hemodynamic indices (i.e. augmentation pressure, augmentation index, pulse wave velocity, systolic and diastolic pressure time integral, subendocardial viability index) at baseline and 6 months after starting baroreflex activation therapy in 25 patients with resistant hypertension.

RESULTS

Apart from peripheral blood pressure reduction, 6 months of baroreflex activation therapy significantly reduced mean central aortic blood pressure from 109.7 ± 20.5 to 97.4 ± 18.8 mm Hg (P < 0.01) and aortic pulse pressure from 62.9 ± 18.6 to 55.2 ± 16.0 mm Hg (P < 0.01). Aortic augmentation pressure and augmentation index at a heart rate of 75 b.p.m. were significantly reduced by 4.3 ± 7.9 mm Hg (P = 0.01) and 3.5 ± 6.8% (P = 0.02). Additionally, pulse wave velocity decreased from 10.3 ± 2.6 to 8.6 ± 1.3 m/s (P < 0.01) 6 months after starting baroreflex activation therapy. Systolic pressure time integral was significantly reduced (P = 0.03), whereas subendocardial viability index remained unchanged.

CONCLUSION

Apart from peripheral blood pressure, baroreflex activation therapy reduces central blood pressure, augmentation index at a heart rate of 75 b.p.m. and pulse wave velocity in patients with resistant hypertension, suggesting strong potential to reduce cardiovascular risk.

Measurement of Arterial Stiffness: A Novel Tool of Risk Stratification in Hypertension

Cardiovascular diseases are the leading causes of morbidity and mortality in industrialized countries worldwide, despite highly effective preventive treatments available. As a difference continues to exist between the estimated and true number of events, further improvement of risk stratification is an essential part of cardiovascular research.Among hypertensive patients measurement of arterial stiffness parameters, like carotid-femoral pulse wave velocity (cfPWV) or brachial-ankle pulse wave velocity (baPWV) can contribute to the identification of high-risk subpopulation of patients. This is a hot topic of vascular research including the possibility of the non-invasive measurement of central hemodynamics, wave reflections and recently, 24-h arterial stiffness monitoring as well. This chapter discusses the past and the present of this area including the scientific achievements with cfPWV, baPWV and other measures, provides a short overview of methodologies and the representation of arterial stiffness parameters in guidelines.

Ghrelin restores nitric oxide availability in resistance circulation of essential hypertensive patients: role of NAD(P)H oxidase

AIMS

We assessed whether acute intra-arterial infusion of exogenous ghrelin can improve endothelial dysfunction by restoring nitric oxide (NO) availability in the forearm microcirculation of essential hypertensive patients. The effect of ghrelin on endothelial dysfunction (pressurized myograph), vascular oxidative stress generation (fluorescent dihydroethidium), and phosphorylation of p47phox (western blot), an index of NAD(P)H oxidase activation, in isolated small arteries taken from essential hypertensive patients (subcutaneous biopsy) were also investigated.

METHODS AND RESULTS

In 18 normotensive control subjects and 18 essential hypertensive patients, we studied the forearm blood flow (strain-gauge plethysmography) response to intra-arterial acetylcholine, repeated under NO synthase inhibitor N(G)-monomethyl-l-arginine (l-NMMA) or the antioxidant ascorbic acid. The protocol was repeated at the end of exogenous ghrelin intra-arterial infusion. In hypertensive patients, ghrelin normalized the blunted response to acetylcholine, restored the inhibiting effect of l-NMMA and abrogated the potentiating effect of ascorbic acid on acetylcholine. In controls, ghrelin failed to modify these vascular responses. In hypertensive patients, ghrelin decreased venous levels of malondialdehyde, lipoperoxide, and interleukin-6, and concomitantly increased endogenous antioxidant capacity. Small vessels from hypertensive patients showed an enhanced intravascular oxidative stress, which was strongly and similarly decreased by incubation with ghrelin, the NAD(P)H oxidase inhibitor gp91 ds-tat, or both. Ghrelin also normalized the overexpression of p47 phosphorylation and restored the NO availability in small vessels from hypertensive patients.

CONCLUSIONS

Exogenous ghrelin increases endothelial dysfunction by restoring NO availability in the forearm microcirculation of essential hypertensive patients, an effect ascribable to an antioxidant effect via inhibition of NAD(P)H oxidase activation.

Comparative portal hypotensive effects as propranolol of vitamin D₃ treatment by decreasing intrahepatic resistance in cirrhotic rats

BACKGROUND AND AIM

Vitamin D₃ improves portal hypertension (PH) through the activation of vitamin D receptor (VDR) and calcium-sensing receptor (CaSR) in cirrhotic rats. Propranolol is a non-selective β-blocker that is recommended for the treatment of PH. The present study aims to investigate the detail systemic and hepatic mechanisms of vitamin D₃ and propranolol, alone or in combination, in cirrhotic rats.

METHODS

Common bile duct-ligated and thioacetamide cirrhotic rats were treated with vehicle, propranolol (30 mg/kg/day), vitamin D₃ (0.5 μg/100 g/day, twice weekly), or propranolol + vitamin D₃, separately.

RESULTS

Significantly, propranolol and vitamin D₃ produced a similar magnitude of reduction in portal venous pressure (PVP) in cirrhotic rats through different mechanisms: whereas propranolol decreased PVP by reducing splanchnic hyperemia and cardiac index, vitamin D₃ decreased PVP by decreasing intrahepatic resistance (IHR). However, propranolol + vitamin D₃ did not further decrease PVP in cirrhotic rats. Notably, a marked decrease in hepatic VDR and CaSR expressions was noted in cirrhotic human/rat livers compared with non-cirrhotic human/rat livers. In cirrhotic rats, vitamin D₃ administration decreasing IHR by inhibiting the renin-angiotensin system, hepatic oxidative stress, inflammation/fibrosis, angiotensin II (ANGII) production, CaSR-mediated ANGII hyperresponsiveness, ANGII-induced hepatic stellate cells contraction, and correcting hepatic endothelial dysfunction through upregulation of hepatic VDR, CaSR, and endothelial nitric oxide synthase expressions.

CONCLUSION

Chronic vitamin D₃ treatment alone results in comparative portal hypotensive effects as propranolol alone in cirrhotic rats with PH. Taken together, chronic vitamin D₃ administration was an ideal alternative strategy to effectively improve PH without unwanted systemic side-effects.

Effect of aliskiren on circulating endothelial progenitor cells and vascular function in patients with type 2 diabetes and essential hypertension

BACKGROUND

The aim of this study was to investigate the effects of aliskiren on vascular function and endothelial progenitor cells (EPCs) in patients with type 2 diabetes and essential hypertension.

METHODS

The study enrolled type 2 diabetic patients aged >50 years under stable glycemic control and first diagnosed mild essential hypertension. In phase A (n = 20), patients received aliskiren 150-300 mg daily for 3 months. In phase B (n = 12), hydrochlorothiazide (HCTZ) 12.5-25mg daily substituted for aliskiren for 3 more months. At baseline and at the end of each phase, we assessed (i) brachial blood pressure (BBP); (ii) central aortic systolic pressure (CSP), aortic augmentation index (Aix), and pulse wave velocity (PWV) as markers of arterial stiffness; (iii) brachial artery flow-mediated dilatation (FMD) as a marker of endothelial function; (iv) left ventricular (LV) twisting and untwisting as markers of LV function and (v) EPC numbers in culture of peripheral blood mononuclear cells.

RESULTS

Aliskiren similarly reduced BBP and CSP, increased FMD (P < 0.001) and EPC numbers (P < 0.001), decreased PWV and Aix (P < 0.05), and improved LV twisting and untwisting (P < 0.05). Although substitution of HCTZ sustained BBP at similar levels, CSP and echocardiographic indices nearly returned at baseline levels, and the improvement of FMD, PWV, Aix, and EPC numbers was abolished.

CONCLUSIONS

Aliskiren had a favorable effect on endothelial function and EPCs, reduced arterial stiffness, and improved LV twisting and untwisting. These effects were independent of BBP lowering, as they were not observed after the achievement of similar values of BBP with HCTZ.

Effects of aliskiren- and ramipril-based treatment on central aortic blood pressure in elderly with systolic hypertension: a substudy of AGELESS

BACKGROUND

Systolic hypertension is the most common form of hypertension in elderly patients. There is increasing evidence that measurement of central aortic pressure (CAP) better accounts for cardiovascular risk than brachial blood pressure (BP). The Aliskiren for GEriatric LowEring of SyStolic hypertension (AGELESS) study in elderly patients with systolic hypertension showed that aliskiren-based therapy provided greater reductions in peripheral BP than ramipril-based therapy over 12 and 36 weeks of treatment. Here, we present CAP results in a substudy of elderly patients from the AGELESS study.

METHODS

This was a post hoc analysis of a 36-week, randomized, double-blind, parallel-group, active-controlled, optional-titration study in patients ≥65 years of age with systolic BP ≥140 mmHg. Changes in both central and peripheral BP and pulse pressure (PP) and changes in systolic and PP amplification ratios from baseline to the week 36 end point with aliskiren-based versus ramipril-based therapy were analyzed.

RESULTS

Of the 901 patients randomized in the overall study, 154 patients (aliskiren, n=78; ramipril, n=76) had CAP data. Numerically comparable reductions were seen for central aortic systolic pressure (CASP) in aliskiren-based therapy (baseline: 143.7±15.0; week 36: -20.3±16.2) compared with ramipril-based therapy (baseline: 147.9±11.9; week 36: -20.7±14.6). However, for the change in central aortic diastolic pressure, the least squares mean between-treatment difference (-3.6 mmHg [95% confidence interval, -6.76, -0.43; P=0.0263]) was in favor of aliskiren, while the other changes were comparable between the two groups with a trend in favor of aliskiren for CASP as well (-2.6 mmHg [95% confidence interval, -7.38, 2.19; P=0.2855)]. Correlation coefficients for change from baseline between CASP and systolic BP and between central aortic pulse pressure and PP (r=0.8, P<0.0001) were highly significant.

CONCLUSION

Aliskiren-based therapy provides comparable reductions in CASP to ramipril-based therapy. Although the results did not reach statistical significance, these findings, when coupled with those of the main study, suggest that aliskiren may offer effective control of central BP in elderly patients with systolic hypertension and may be a good alternative to ramipril.

Correlation between anthropometric measurement, lipid profile, dietary vitamins, serum antioxidants, lipoprotein (a) and lipid peroxides in known cases of 345 elderly hypertensive South Asian aged 56-64 y-A hospital based study

OBJECTIVE

To address the association of dietary vitamins, anthropometric profile, lipid profile, antioxidant enzymes and lipid peroxidation in hypertensive participant compared with normotensive healthy controls.

METHODS

Dietary intake of vitamins was assessed by 131 food frequency questionnaire items in both hypertensive participants and normotensive age-sex matched healthy controls. The associated changes in serum antioxidants and lipid peroxidation were also assessed along with lipid profile and anthropometric measurements in both groups of subjects under study.

RESULTS

Dietary vitamins intake was higher in hypertensive participants excepting for vitamin B2 and ascorbic acid compared to normotensive controls. Anthropometric variables in the hypertensive showed significant differences in weight, body mass index, waist circumference, hip circumference, waist-hip ratio and mid-arm circumference. The total cholesterol, low-density lipoprotein cholesterol, triglyceride were significantly higher (P<0.001) in hypertensive except high-density lipoprotein cholesterol which was significantly higher (P<0.001) in normotensive. The serum endogenous antioxidants and enzyme antioxidants were significantly decreased in hypertensive except serum albumin levels compared to normotensive along with concomitant increase in serum lipoprotein (a) malondialdehyde and conjugated diene levels.

CONCLUSIONS

Based on the observations, our study concludes that hypertension is caused due to interplay of several confounding factors namely anthropometry, lipid profile, depletion of endogenous antioxidants and rise in oxidative stress.

Role of aliskiren on arterial stiffness and endothelial function in patients with primary hypertension

Arterial stiffness and endothelial dysfunction are important determinants of cardiovascular events in patients with arterial hypertension. There are few data regarding the role of aliskiren on the central hemodynamics and endothelial function in patients with uncontrolled arterial hypertension. The aim of this study was to assess the addition of aliskiren to other antihypertensive drug treatment for arterial stiffness and endothelial function. Thirty uncontrolled hypertensive patients (mean age, 60.4±12.2 years), without any other cardiovascular risk factors, were enrolled. Augmentation index (AIx) and carotid-femoral pulse wave velocity (cfPWV) by applanation tonometry and reactive hyperemia peripheral arterial tonometry (RH PAT) index using peripheral arterious tonometry at baseline and after 6 months of aliskiren titrated to 300 mg once a day was evaluated. The addition of aliskiren had no effect on values of central AIx (33.26±10.74% vs 28.86±10.74%; P=.36) but did significantly improve values of cfPWV (9.36±2.65 m/s vs 8.72±2.48 m/s; P=.04) and RH PAT index (1.64±0.57 vs 1.75±0.45; P=.05). In addition to improving systolic and diastolic blood pressure, the addition of aliskiren to concomitant antihypertensive drugs in uncontrolled hypertensive patients may be effective in improving aortic stiffness and endothelial function. These results encourage further studies to evaluate the use of aliskiren for cardiovascular prevention.

Differential effects of aliskiren/amlodipine combination and high-dose amlodipine monotherapy on endothelial function in elderly hypertensive patients

BACKGROUND

The aim of this study was to compare the effects of direct renin inhibitor, aliskiren, and amlodipine combination therapy with those of high-dose amlodipine monotherapy on endothelial function in elderly hypertensive patients.

METHODS

Participants included 105 patients (mean age 77 years) who had receive 5mg amlodipine for 4 weeks. Patients were allocated to the aliskiren/amlodipine group (AL/AM) or the high-dose amlodipine (AM) group. The AL/AM group received 150mg aliskiren in addition to 5mg amlodipine for 8 weeks; then the dose of aliskiren was doubled to 300mg for another 8 weeks. The AM group received 10mg amlodipine for 16 weeks. Of the 105 patients, 87 who underwent measurements of brachial flow-mediated vasodilation (FMD) and nitroglycerin-mediated vasodilation (NMD) before and after the study were included in the analysis.

RESULTS

Blood pressure-lowering effects were similar in the 2 groups. Plasma renin activity significantly decreased in the AL/AM group (P < 0.001) but increased in the AM group (P < 0.001). Improvement of FMD was found in the AL/AM group (2.6% to 3.7%, P = 0.001) but not in the AM group, while NMD did not change in either group. The changes in 24-hour systolic blood pressure (r = -0.60, P < 0.001) and diastolic blood pressure (r = -0.46, P = 0.004) were significantly correlated with improvement of FMD in the AL/AM group but not in the AM group.

CONCLUSION

Addition of aliskiren improved endothelial function in elderly hypertensive patients treated with amlodipine.

CLINICAL TRIAL REGISTRY NUMBER

UMIN000010163.

Effects of renin-angiotensin-aldosterone system inhibitors and beta-blockers on markers of arterial stiffness

Antihypertensive agents may, even within the same class, exert variable effects on arterial stiffness variables. Nebivolol could have a better impact than atenolol on arterial stiffness, by increasing the bioavailability of endothelium-derived nitric oxide. Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) increase plasma renin activity (enhancing the production of angiotensin II via non-ACE-related pathways) whereas aliskiren does not, potentially affecting central hemodynamics differently. We compared the effects of two renin-angiotensin-aldosterone system (RAAS) inhibitors (quinapril and aliskiren) and 2 beta-blockers (atenolol and nebivolol) on arterial stiffness variables. Treatment-naïve patients (n = 72; 68.1% males; age, 47.6 ± 10.6 years) with uncomplicated stage I-II essential hypertension were randomly assigned to quinapril, aliskiren, atenolol, or nebivolol for 10 weeks. Central systolic and diastolic blood pressure (BP), central pulse pressure (PP), augmentation index (AIx), and pulse wave velocity (PWV) were measured at baseline, 2, and 10 weeks. The same measurements were performed in 20 normotensive subjects (65.0% males; age, 40.0 ± 8.9 years). Peripheral and central systolic and diastolic BP, peripheral PP, and PWV were significantly and similarly reduced by all agents. However, PWV continued to decline between the second and last visit in patients on quinapril and aliskiren but did not change in those on nebivolol or atenolol. Central PP and AIx decreased in patients on quinapril, aliskiren, and nebivolol but did not change in those taking atenolol. The decrease in central PP and AIx did not differ between patients on quinapril, aliskiren, and nebivolol. Despite similar reductions in peripheral BP, atenolol is less effective than nebivolol and RAAS inhibitors in improving central pulsatile hemodynamics. Aliskiren exerts similar effects on markers of arterial stiffness as quinapril. The clinical relevance of these differences remains to be established.

Chronic renin inhibition lowers blood pressure and reduces upright muscle sympathetic nerve activity in hypertensive seniors

Cardiovascular risk remains high in patients with hypertension even with adequate blood pressure (BP) control. One possible mechanism may be sympathetic activation via the baroreflex. We tested the hypothesis that chronic inhibition of renin reduces BP without sympathetic activation, but diuresis augments sympathetic activity in elderly hypertensives. Fourteen patients with stage-I hypertension (66 ± 5 (SD) years) were treated with a direct renin inhibitor, aliskiren (n = 7), or a diuretic, hydrochlorothiazide (n = 7), for 6 months. Muscle sympathetic nerve activity (MSNA), BP, direct renin and aldosterone were measured during supine and a graded head-up tilt (HUT; 5 min 30° and 20 min 60°), before and after treatment. Sympathetic baroreflex sensitivity (BRS) was assessed. Both groups had similar BP reductions after treatment (all P < 0.01), while MSNA responses were different between hydrochlorothiazide and aliskiren (P = 0.006 pre/post × drug). Both supine and upright MSNA became greater after hydrochlorothiazide treatment (supine, 72 ± 18 post vs. 64 ± 15 bursts (100 beats)(-1) pre; 60° HUT, 83 ± 10 vs. 78 ± 13 bursts (100 beats)(-1); P = 0.002). After aliskiren treatment, supine MSNA remained unchanged (69 ± 13 vs. 64 ± 8 bursts (100 beats)(-1)), but upright MSNA was lower (74 ± 15 vs. 85 ± 10 bursts (100 beats)(-1); P = 0.012 for pre/post × posture). Direct renin was greater after both treatments (both P < 0.05), while upright aldosterone was greater after hydrochlorothiazide only (P = 0.002). The change in upright MSNA by the treatment was correlated with the change of aldosterone (r = 0.74, P = 0.002). Upright sympathetic BRS remained unchanged after either treatment. Thus, chronic renin inhibition may reduce upright MSNA through suppressed renin activity, while diuresis may evoke sympathetic activation via the upregulated renin-angiotensin-aldosterone system, without changing intrinsic sympathetic baroreflex function in elderly hypertensive patients.

The (pro)renin receptor blocker handle region peptide upregulates endothelium-derived contractile factors in aliskiren-treated diabetic transgenic (mREN2)27 rats

BACKGROUND

Elevated prorenin levels associate with microvascular complications in patients with diabetes mellitus, possibly because prorenin affects vascular function in diabetes mellitus, for example by generating angiotensins following its binding to the (pro)renin receptor [(P)RR]. Here we evaluated whether the renin inhibitor aliskiren, with or without the putative (P)RR antagonist handle region peptide (HRP) improved the disturbed vascular function in diabetic TGR(mREN2)27 rats, a high-prorenin, high-(P)RR hypertensive model.

METHODS

Telemetry transmitters were implanted to monitor blood pressure. After 3 weeks of treatment, rats were sacrificed, and iliac and mesenteric arteries were removed to evaluate vascular reactivity.

RESULTS

Diabetes mellitus enhanced the contractile response to nitric oxide synthase (NOS) blockade, potentiated the response to phenylephrine, diminished the effectiveness of endothelin type A (ETA) receptor blockade and allowed acetylcholine to display constrictor, cyclo-oxygenase-2 mediated, endothelium-dependent responses in the presence of NOS inhibition and blockers of endothelium-derived hyperpolarizing factors. Aliskiren normalized blood pressure, suppressed renin activity, and reversed the above vascular effects, with the exception of the altered effectiveness of ETA receptor blockade. Remarkably, when adding HRP on top of aliskiren, its beneficial vascular effects either disappeared or were greatly diminished, although HRP did not alter the effect of aliskiren on blood pressure and renin activity.

CONCLUSIONS

Renin inhibition improves vascular dysfunction in diabetic hypertensive rats, and HRP counteracts this effect independently of blood pressure and angiotensin. (P)RR blockade therefore is unlikely to be a new tool to further suppress the renin-angiotensin system (RAS) on top of existing RAS blockers.

The direct renin inhibitor aliskiren improves vascular remodelling in transgenic rats harbouring human renin and angiotensinogen genes

In the present study, we tested the hypothesis that chronic treatment with the direct rennin inhibitor aliskiren improves the remodelling of resistance arteries in dTGR (double-transgenic rats). dTGR (5 weeks) were treated with aliskiren (3 mg/kg of body mass per day) or ramipril (1 mg/kg of body mass per day) for 14 days and compared with age-matched vehicle-treated dTGR. BP (blood pressure) was similarly reduced in both aliskiren-treated and ramipril-treated rats compared with control dTGR (167±1 and 169±2 mmHg compared with 197±4 mmHg respectively; P<0.05). The M/L (media-to-lumen) ratio assessed on pressurized preparations was equally reduced in aliskiren-treated and ramipril-treated rats compared with controls (6.3±0.5 and 6.4±0.2% compared with 9.8±0.4% respectively; P<0.05). Endothelium-dependent and -independent relaxations were similar among the groups. L-NAME (NG-nitro-L-arginine methyl ester) significantly reduced acetylcholine-induced dilation in drug-treated dTGR. This effect was significantly more prominent in aliskiren-treated rats. eNOS (endothelial NO synthase) expression showed a 2-fold increase only in aliskiren-treated dTGR as compared with controls (P<0.01) and ramipril-treated dTGR (P<0.05). Plasma nitrite, as an index of NO production, was significantly increased in dTGR treated with either aliskiren or ramipril compared with controls. Only aliskiren induced a 2-fold increase in plasma nitrite, which was significantly greater than that induced by ramipril (P<0.05). gp91phox expression and ROS (reactive oxygen species) production in aorta were significantly and similarly reduced by both drugs. In conclusion, equieffective hypotensive doses of aliskiren or ramipril reduced the M/L ratio of mesenteric arteries and improved oxidative stress in dTGR. However, only aliskiren increased further NO production in the vasculature. Hence, in dTGR, direct renin inhibition induces favourable effects similar to that induced by ACE (angiotensin-converting enzyme) inhibition in improving vascular remodelling through different mechanisms.

Renin-Angiotensin system and sympathetic neurotransmitter release in the central nervous system of hypertension

Many Studies suggest that changes in sympathetic nerve activity in the central nervous system might have a crucial role in blood pressure control. The present paper discusses evidence in support of the concept that the brain renin-angiotensin system (RAS) might be linked to sympathetic nerve activity in hypertension. The amount of neurotransmitter release from sympathetic nerve endings can be regulated by presynaptic receptors located on nerve terminals. It has been proposed that alterations in sympathetic nervous activity in the central nervous system of hypertension might be partially due to abnormalities in presynaptic modulation of neurotransmitter release. Recent evidence indicates that all components of the RAS have been identified in the brain. It has been proposed that the brain RAS may actively participate in the modulation of neurotransmitter release and influence the central sympathetic outflow to the periphery. This paper summarizes the results of studies to evaluate the possible relationship between the brain RAS and sympathetic neurotransmitter release in the central nervous system of hypertension.

Efficacy of aliskiren and valsartan in hypertensive patients with albuminuria: a randomized parallel-group study

INTRODUCTION

Blockade of the renin-angiotensin system (RAS) is a critical approach to the management of hypertension, especially in proteinuric patients. It is well proven that the direct renin inhibitor aliskiren shows comparable clinical efficacy to the angiotensin II receptor blocker valsartan on blood pressure control and albuminuria. However, there is only limited data on the hand-to-hand effectiveness of these two RAS blockers in improving arterial stiffness. We tested whether aliskiren or valsartan would improve arterial stiffness in hypertensive patients with albuminuria who are already on antihypertensive therapy.

MATERIAL AND METHODS

Thirty-four patients with hypertension and albuminuria < 1 g, after a wash-out period of three weeks, were randomized to aliskiren or valsartan in a 24-week randomized parallel-group study.

RESULTS

A nonsignificant difference in blood pressure was seen between the two treatment groups. Albuminuria was significantly reduced in both groups (56% for the aliskiren group, p < 0.05, and 38% for the valsartan group, p < 0.05). Only valsartan but not aliskiren significantly reduced carotid-femoral pulse wave velocity (-1.1 ± 0.8 m/s (p = 0.02) for valsartan and +0.1 ± 0.7 m/s (ns) for aliskiren).

CONCLUSION

The results of our study showed that valsartan improves arterial stiffness to a significantly greater extent than aliskiren, despite a similar antihypertensive and antiproteinuric effect.

Direct renin inhibitor prevents and ameliorates insulin resistance, aortic endothelial dysfunction and vascular remodeling in fructose-fed hypertensive rats

Angiotensin-converting enzyme inhibitors and angiotensin II type 1 receptor blockers can improve insulin resistance and vascular dysfunction in insulin-resistant rats; however, there are few reports on the effects of direct renin inhibitors on these conditions. We investigated the effects of a direct renin inhibitor, aliskiren, on insulin resistance, aortic endothelial dysfunction and vascular remodeling in fructose-fed hypertensive rats. Male Wistar-Kyoto rats were divided into four groups (n=6 per group) and studied for 8 weeks: Group Con: standard chow diet; group Fru: high-fructose diet (60% fructose); Group FruA: high-fructose diet with concurrent aliskiren treatment (100 mg kg(-1) per day); and Group FruB: high-fructose diet with subsequent aliskiren treatment 4 weeks later. Blood was collected for biochemical assays, and isolated rings of the thoracic aorta were obtained for analysis of vascular reactivity, vascular structure and lipid peroxide. Rats fed with high-fructose diets developed significant systolic hypertension, decreased plasma nitrite (NO(2); nitric oxide metabolite) levels and increased plasma glucose, insulin, triglyceride, total cholesterol and aortic lipid peroxide levels, and aortic wall thickness compared with control rats. Aliskiren treatment, either concurrent or subsequent, elevated plasma NO(2) levels and reduced systolic hypertension, insulin resistance, dyslipidemia, aortic lipid peroxide levels and aortic wall hypertrophy in FHR. The peak endothelium-dependent aortic relaxations were significantly higher in rats that received aliskiren treatment than in those that did not. In conclusion, our findings suggest that aliskiren prevents and ameliorates insulin resistance, aortic endothelial dysfunction and oxidative vascular remodeling in fructose-fed hypertensive rats.