Effects of ACE inhibition and AT1-receptor antagonism on endothelial function and insulin sensitivity in essential hypertensive patients

Insulin Secretion, Sensitivity, and Kidney Function in Young Individuals With Type 2 Diabetes

OBJECTIVE

β-Cell dysfunction and insulin resistance magnify the risk of kidney injury in type 2 diabetes. The relationship between these factors and intraglomerular hemodynamics and kidney oxygen availability in youth with type 2 diabetes remains incompletely explored.

RESEARCH DESIGN AND METHODS

Fifty youth with type 2 diabetes (mean age ± SD 16 ± 2 years; diabetes duration 2.3 ± 1.8 years; 60% female; median HbA1c 6.4% [25th, 75th percentiles 5.9, 7.6%]; BMI 36.4 ± 7.4 kg/m2; urine albumin-to-creatinine ratio [UACR] 10.3 [5.9, 58.0] mg/g) 21 control participants with obesity (OCs; age 16 ± 2 years; 29% female; BMI 37.6 ± 7.4 kg/m2), and 20 control participants in the normal weight category (NWCs; age 17 ± 3 years; 70% female; BMI 22.5 ± 3.6 kg/m2) underwent iohexol and p-aminohippurate clearance to assess glomerular filtration rate (GFR) and renal plasma flow, kidney MRI for oxygenation, hyperglycemic clamp for insulin secretion (acute C-peptide response to glucose [ACPRg]) and disposition index (DI; ×103 mg/kg lean/min), and DXA for body composition.

RESULTS

Youth with type 2 diabetes exhibited lower DI (0.6 [0.0, 1.6] vs. 3.8 [2.4, 4.5] × 103 mg/kg lean/min; P < 0.0001) and ACPRg (0.6 [0.3, 1.4] vs. 5.3 [4.3, 6.9] nmol/L; P < 0.001) and higher UACR (10.3 [5.9, 58.0] vs. 5.3 [3.4, 14.3] mg/g; P = 0.003) and intraglomerular pressure (77.8 ± 11.5 vs. 64.8 ± 5.0 mmHg; P < 0.001) compared with OCs. Youth with type 2 diabetes and OCs had higher GFR and kidney oxygen availability (relative hyperoxia) than NWCs. DI was associated inversely with intraglomerular pressure and kidney hyperoxia.

CONCLUSIONS

Youth with type 2 diabetes demonstrated severe β-cell dysfunction that was associated with intraglomerular hypertension and kidney hyperoxia. Similar but attenuated findings were found in OCs.

Insulin and the kidneys: a contemporary view on the molecular basis

Insulin is a hormone that is composed of 51 amino acids and structurally organized as a hexamer comprising three heterodimers. Insulin is the central hormone involved in the control of glucose and lipid metabolism, aiding in processes such as body homeostasis and cell growth. Insulin is synthesized as a large preprohormone and has a leader sequence or signal peptide that appears to be responsible for transport to the endoplasmic reticulum membranes. The interaction of insulin with the kidneys is a dynamic and multicenter process, as it acts in multiple sites throughout the nephron. Insulin acts on a range of tissues, from the glomerulus to the renal tubule, by modulating different functions such as glomerular filtration, gluconeogenesis, natriuresis, glucose uptake, regulation of ion transport, and the prevention of apoptosis. On the other hand, there is sufficient evidence showing the insulin receptor's involvement in renal functions and its responsibility for the regulation of glucose homeostasis, which enables us to understand its contribution to the insulin resistance phenomenon and its association with the progression of diabetic kidney disease.

Comparative Evaluation of Captopril, Spironolactone, and Carvedilol Effect on Endothelial Function in Breast Cancer Women Undergoing Chemotherapy

Background

Breast cancer is the most prevalent malignancy in females which needs chemotherapy treatment. Studies demonstrated that anti-cancer agents used for chemotherapy in cancer patient causes endothelium dysfunction. Several researches showed the efficacy of angiotensin-converting enzyme inhibitors, Carvedilol and Spironolactone on improving endothelial function. This study aimed to evaluate the effect of the combination of Spironolactone, Carvedilol, and Captopril on endothelial function in breast cancer patients.

Materials and Methods

This study is a prospective Randomized Clinical Trial in breast cancer patients who underwent chemotherapy. Patients were divided into two groups who received the combination of Captopril, Spironolactone, and Carvedilol or standard regimen for 3 months during chemotherapy. Before and after intervention, ejection fraction (EF), E/A ratio and e' and flow-mediated dilation (FMD) properties were calculated and then compared.

Results

Fifty-eight patients with a mean age of 47.57 ± 9.46 years were evaluated. The mean FMD after the intervention is statistically different in case and controls (<0.001). E/A ratio and e' are not statistically different between groups after intervention. The mean EF was not statistically different between the two groups after intervention.

Conclusion

Prescribing combination of Carvedilol, Spironolactone, and Captopril in breast cancer patients undergoing chemotherapy can improve endothelial function and may have beneficial effects on diastolic function.

Comparative Efficacy of Antihypertensive Agents in Flow-Mediated Vasodilation of Patients with Hypertension: Network Meta-Analysis of Randomized Controlled Trial

Hypertension induces both structural and functional changes in blood vessels, thereby increasing endothelial dysfunction, which in turn, contributes to an increase in blood pressure. A popular and widely used noninvasive tool, flow-mediated dilation (FMD), is used to examine peripheral artery endothelium-dependent dilation. This study aimed to compare the efficacies of different classes of antihypertensive agents based on their effects on FMD. PubMed, Embase, and Cochrane Library were queried till November 1, 2020. Comparative studies on the efficacies of two or more antihypertensive agents or placebos for hypertensive patients were included. The outcomes were variations in mean systolic and diastolic blood pressure. Two reviewers independently reviewed and filtered the literature and extracted the data; the Cochrane “risk of bias” method was used to evaluate the methodological quality of the randomized controlled trials. A network meta-analysis was performed using Stata 15.0 software with a total of 49 studies. Subgroup analysis based on age and duration of treatments was performed. As compared to the placebo group, patients receiving the antihypertensive drugs exhibited significantly enhanced FMD (ARB + CCB: 4.01%, 95% CI, 0.92–7.11%, p < 0.001; ACEI + ARB: 2.81%, 95% CI, 1.19–4.43%, p < 0.001; ACEI: 2.55%, 95% CI, 1.34–3.77%, p < 0.001; ARB: 2.22%, 95% CI, 1.05–3.38%, p < 0.001; β-blocker: 2.23%, 95% CI, 0.93–3.52%, p < 0.001). In the SUCRA curve for network meta-analysis, the combination of CCB and ARB was found to be the most effective in increasing FMD (SUCRA = 89.0%), followed by ACEI monotherapy (SUCRA = 74.2%). ARB combined with CCB was superior in improving the endothelial function measured as the FMD; ACEI monotherapy was the most effective treatment among the antihypertension medications. There were no significant differences between antihypertensive drug-based monotherapies.

Angiotensin II inhibition: a potential treatment to slow the progression of sarcopenia

Sarcopenia is defined as the progressive and generalized loss of skeletal muscle mass and strength, which is associated with increased likelihood of adverse outcomes including falls, fractures, physical disability, and mortality. The etiology of sarcopenia has been postulated to be multifactorial with genetics, aging, immobility, nutritional deficiencies, inflammation, stress, and endocrine factors all contributing to the imbalance of muscle anabolism and catabolism. The prevalence of sarcopenia is estimated to range from 13 to 24% in adults over 60 years of age and up to 50% in persons aged 80 and older. As the population continues to age, the prevalence of sarcopenia continues to increase and is expected to affect 500 million people by the year 2050. Sarcopenia impacts the overall health of patients through limitations in functional status, increase in hospital readmissions, poorer hospital outcomes, and increase in overall mortality. Thus, there exists a need to prevent or reduce the occurrence of sarcopenia. Here, we explore the potential mechanisms and current studies regarding angiotensin receptor blockers (ARBs) and angiotensin-converting enzyme (ACE) inhibitors on reducing the development of sarcopenia through the associated changes in cardiovascular function, renal function, muscle fiber composition, inflammation, endothelial dysfunction, metabolic efficiency, and mitochondrial function.

Angiotensin-converting enzyme inhibitors versus angiotensin II receptor blockers on insulin sensitivity in hypertensive patients: A meta-analysis of randomized controlled trials

Introduction

This meta-analysis aimed to summarize the available evidence to compare angiotensin-converting enzyme (ACE) inhibitors with angiotensin II receptor blockers (ARBs) on improving insulin sensitivity in hypertensive patients.

Methods

Randomized controlled trials (RCTs) comparing ACE inhibitors versus ARBs published with outcomes on homeostasis model assessment of IR (HOMA-IR), glucose infusion rate (GIR), the quantitative insulin sensitivity check index (QUICKI), insulin sensitivity index (ISI) composite, fasting plasma glucose (FPG), fasting plasma insulin (FPI), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were searched through 5 databases. Data were searched from their inception to July 5, 2020. Stata 14.0 was used to perform the meta-analysis.

Results

Eleven RCTs (n = 1015) were included in this meta-analysis. Pooled analysis of studies showed no significant difference in HOMA-IR between ARBs and ACE inhibitors (WMD = -0.09, 95% CI: -0.69 to 0.50, P = 0.755); however, subgroup analysis of therapeutic duration showed a significant difference in HOMA-IR between ARBs and ACE inhibitors among the long-term intervention subgroup (>12 weeks) (WMD = 0.41, 95% CI: 0.06 to 0.76, P = 0.022) and hypertensive patients with diabetes mellitus subgroup (WMD = 0.55, 95% CI: 0.49 to 0.61, P < 0.001); results showed no significant difference between ARBs and ACE inhibitors on QUICKI score (WMD = -0.00, 95% CI: -0.03 to 0.03, P = 0.953) in hypertensive patients; however, the efficacy of ACE inhibitors on improving GIR and ISI composite was significantly better than that of ARBs (WMD = -1.09, 95% CI: -1.34 to -0.85, P < 0.001; WMD = -0.80, 95% CI: -1.24 to -0.36, P < 0.001, respectively). Furthermore, no significant differences were noted on FPG (WMD = 0.72, 95% CI: -1.39 to 2.83, P = 0.505), FPI (WMD = -0.48, 95% CI: -1.60 to 0.64, P = 0.398), SBP (WMD = -0.65, 95% CI: -1.76 to 0.46, P = 0.254), and DBP (WMD = -0.30, 95% CI: -1.70 to 1.10, P = 0.675) between ARBs and ACE inhibitors.

Conclusion

Results from this meta-analysis showed that ACE inhibitors resulted in more effective improvement of HOMA-IR compared with ARBs among the long-term intervention and hypertensive patients with DM subgroup; furthermore, the efficacy of ACE inhibitors on improving GIR and ISI composite was significantly better than that of ARBs in hypertensive patients. However, ARBs had no significant difference in QUICKI score, FPG, FPI, SBP, and DBP compared with ACE inhibitors. Larger and better-designed studies are needed to further verify this conclusion.

Endothelial Dysfunction in Chronic Kidney Disease, from Biology to Clinical Outcomes: A 2020 Update

The vascular endothelium is a dynamic, functionally complex organ, modulating multiple biological processes, including vascular tone and permeability, inflammatory responses, thrombosis, and angiogenesis. Endothelial dysfunction is a threat to the integrity of the vascular system, and it is pivotal in the pathogenesis of atherosclerosis and cardiovascular disease. Reduced nitric oxide (NO) bioavailability is a hallmark of chronic kidney disease (CKD), with this disturbance being almost universal in patients who reach the most advanced phase of CKD, end-stage kidney disease (ESKD). Low NO bioavailability in CKD depends on several mechanisms affecting the expression and the activity of endothelial NO synthase (eNOS). Accumulation of endogenous inhibitors of eNOS, inflammation and oxidative stress, advanced glycosylation products (AGEs), bone mineral balance disorders encompassing hyperphosphatemia, high levels of the phosphaturic hormone fibroblast growth factor 23 (FGF23), and low levels of the active form of vitamin D (1,25 vitamin D) and the anti-ageing vasculoprotective factor Klotho all impinge upon NO bioavailability and are critical to endothelial dysfunction in CKD. Wide-ranging multivariate interventions are needed to counter endothelial dysfunction in CKD, an alteration triggering arterial disease and cardiovascular complications in this high-risk population.

Potential Protective Role of Blood Pressure-Lowering Drugs on the Balance between Hemostasis and Fibrinolysis in Hypertensive Patients at Rest and During Exercise

In patients with hypertension, the triad represented by endothelial dysfunction, platelet hyperactivity, and altered fibrinolytic function disturbs the equilibrium between hemostasis and fibrinolysis and translates into a hypercoagulable state, which underlies the risk of thrombotic complications. This article reviews the scientific evidence regarding some biological effects of antihypertensive drugs, which can protect patients from the adverse consequences of hypertensive disease, improving endothelial function, enhancing antioxidant activity, and restoring equilibrium between hemostatic and fibrinolytic factors. These protective effects appear not to be mediated through blood pressure reduction and are not shared by all molecules of the same pharmacological class.

Insulin receptors in the kidneys in health and disease

Insulin is an important hormone that affects various metabolic processes, including kidney function. Impairment in insulin’s action leads to insulin resistance in the target tissue. Besides defects in post-receptor insulin signaling, impairment at the receptor level could significantly affect insulin sensitivity of the target tissue. The kidney is a known target of insulin; however, whether the kidney develops “insulin resistance” is debatable. Regulation of the insulin receptor (IR) expression and its function is very well studied in major metabolic tissues like liver, skeletal muscles, and adipose tissue. The physiological relevance of IRs in the kidney has recently begun to be clarified. The credit goes to studies that showed a wide distribution of IR throughout the nephron segments and their reduced expression in the insulin resistance state. Moreover, altered renal and systemic metabolism observed in mice with targeted deletion of the IR from various epithelial cells of the kidney has strengthened this proposition. In this review, we recapitulate the crucial findings from literature that have expanded our knowledge regarding the significance of the renal IR in normal- and insulin-resistance states.

A causal link between oxidative stress and inflammation in cardiovascular and renal complications of diabetes

Chronic renal and vascular oxidative stress in association with an enhanced inflammatory burden are determinant processes in the development and progression of diabetic complications including cardiovascular disease (CVD), atherosclerosis and diabetic kidney disease (DKD). Persistent hyperglycaemia in diabetes mellitus increases the production of reactive oxygen species (ROS) and activates mediators of inflammation as well as suppresses antioxidant defence mechanisms ultimately contributing to oxidative stress which leads to vascular and renal injury in diabetes. Furthermore, there is increasing evidence that ROS, inflammation and fibrosis promote each other and are part of a vicious connection leading to development and progression of CVD and kidney disease in diabetes.

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.

Angiotensin receptor blockers & endothelial dysfunction: Possible correlation & therapeutic implications

The endothelium is one of the most important constituents of vascular homeostasis, which is achieved through continual and balanced production of different relaxing and contractile factors. When there is a pathological disturbance in release of these products, endothelial dysfunction (ED) will probably occur. ED is considered to be the initial step in the development of atherosclerosis. This pathological activation and inadequate functioning of endothelial cells was shown to be to some extent a reversible process, which all together resulted in increased interest in investigation of different beneficial treatment options. To this point, the pharmacological approach, including for example, the use of angiotensin-converting enzyme inhibitors or statins, was clearly shown to be effective in the improvement of ED. One of many critical issues underlying ED represents instability in the balance between nitric oxide and angiotensin II (Ang II) production. Considering that Ang II was confirmed to be important for the development of ED, the aim of this review article was to summarize the findings of up to date clinical studies associated with therapeutic application of angiotensin receptor blockers and improvement in ED. In addition, it was of interest to review the pleiotropic actions of angiotensin receptor blockers linked to the improvement of ED. The prospective, randomized, double-blind, placebo or active-controlled clinical trials were identified and selected for the final evaluation.

Effect of losartan and atenolol on insulin sensitivity in nondiabetic hypertensive patients

OBJECTIVE

To study the effects of losartan and atenolol on glucometabolic parameters in nondiabetic hypertensive patients.

MATERIALS AND METHODS

In a prospective, open-label, parallel group study, nondiabetic patients with mild to moderate hypertension were randomized to either losartan (titrated from 50 to 100 mg/day, n = 20) or atenolol (titrated from 25 mg to 100 mg/day, n = 20) for period of 24 weeks. At baseline, 12 and 24 weeks fasting plasma glucose (FPG), fasting plasma insulin (FPI), homeostasis model assessment for insulin resistance (HOMA-IR) apart from lipid parameters, mean systolic, and diastolic blood pressures levels were determined.

RESULTS

At the end of study, losartan significantly (P < 0.05) reduced FPG, FPI, and HOMA-IR compared to atenolol and baseline. While atenolol increased the HOMA-IR levels significantly compared to the baseline.

CONCLUSIONS

Losartan improved the insulin sensitivity while atenolol worsened it. Losartan is better than atenolol for its effects on the glucose-insulin metabolism.

Effect of Angiotensin Receptor Blockers on Flow-Mediated Vasodilation: A Meta-Analysis of Randomized Controlled Trials

Background: In a meta-analysis, we investigated the effects of angiotensin receptor blockers (ARBs) in comparison to placebo or other classes of antihypertensive drugs on endothelial function, which was measured by brachial flow-mediated vasodilation (FMD). Methods: We searched for randomized controlled trials that compared ARBs with placebo or other classes of antihypertensive drugs in improving FMD. A random-effect model was used to compute pooled estimates. Results: In 13 trials (n = 529), ARBs were more efficacious in improving brachial FMD than placebo [pooled weighted mean change difference (WMD) 1.34%, 95% CI, 0.93-1.75%, p < 0.001]. In 15 trials (n = 918), treatment with ARBs had a significant effect on brachial FMD when compared with other antihypertensive drugs (pooled WMD 0.59%, 95% CI, 0.20-0.98%, p = 0.003 with significant heterogeneity). ARBs were also more efficacious in improving brachial FMD than calcium channel blockers (CCBs; pooled WMD 1.61%, 95% CI, 0.72-2.49%, p < 0.001) but not the other classes of drugs (p ≥ 0.072). Conclusions: This meta-analysis shows that ARBs improve brachial FMD, a marker of endothelial function, and that they are superior to placebo and CCBs. There was no significant difference in the effect on brachial FMD between ARBs and the other antihypertensive drugs.

A meta-analysis of the effects of angiotensin converting enzyme inhibitors and angiotensin II receptor blockers on insulin sensitivity in hypertensive patients without diabetes

AIMS

This study sought to compare the effects of angiotensin converting enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARB) on insulin sensitivity (IS) in hypertensive patients without diabetes.

METHODS

Studies on the observation of IS in hypertensive patients without diabetes who received ACEI and ARB prior to December 2013 was collected using computer-based retrieval of the PUBMED, EMBASE, and COCHRANE databases. The primary indicators included IS, fasting plasma glucose (FPG), and fasting plasma insulin (FPI). The secondary indicators included systolic blood pressure (SBP) and diastolic blood pressure (DBP). A meta-analysis was performed using the STATA and Review Manager 5.2 software. The effects of these two drugs on IS in hypertensive patients without diabetes were analyzed using the fixed effect model and the random effect model.

RESULTS

A total of 203 cases of patients involved in 4 clinical studies were included. As compared to ARB, ACEI treatment resulted in more effective improvement of IS in hypertensive patients without diabetes (SMD: 0.45, 95% CI 0.17-0.73), although these two drugs did not show significant differences with regards to FPG (WMD: 0.00, 95% CI -0.19-0.20), FPI (WMD: -0.34, 95% CI -1.31-0.63), SBP (WMD: 2.85, 95% CI -1.55-7.24), and DBP (WMD: 0.81, 95% CI -1.12-2.75).

CONCLUSION

In patients showing no significant difference in blood pressure control, the comparison between ACEI and ARB showed that the former type of drug more effectively relieved IS in hypertensive patients without diabetes.

Angiotensin II receptor blockers improve peripheral endothelial function: a meta-analysis of randomized controlled trials

OBJECTIVE(S)

Several studies have assessed the effect of angiotensin II receptor blockers (ARBs) on peripheral endothelial dysfunction as measured by flow-mediated vasodilatation (FMD), a widely-used indicator for endothelial function. We conducted a meta-analysis to investigate the effect in comparison to placebo or no treatment and other antihypertensives.

METHODS

MEDLINE, Cochrane library and EMBASE were searched to September 2013 for randomized controlled trials (RCTs) that assessed the effect of ARBs versus placebo or no treatment and other antihypertensives (angiotensin-converting enzyme inhibitors (ACEIs), calcium channel blockers (CCBs), β-blockers, diuretics) by forearm FMD. Furthermore, we also use meta-regression to analyze the relationship between the endothelial function and the duration of ARBs treatments.

RESULTS

In 11 trials including 590 patients, ARBs (n = 315) significantly improved FMD (1.36%, 95% confidence internal [CI]:1.28 to 1.44) versus placebo or no treatment (n = 275). In 16 trials that included 1028 patients, ARBs (n = 486) had a significant effect (0.59%, 95% CI: 0.25 to 0.94) on FMD when compared with other antihypertensives (n = 542). In 8 trials, ARBs (n = 174) had no significant effect (-0.14%, 95% CI: -0.32 to 0.03) compared with ACEI (n = 173). Compared with others, the benefits of ARBs, respectively, were 1.67% (95% CI: 0.65 to 0.93) in 7 trials with CCBs, 0.79% (95% CI: 0.42 to 1.01) with β-blockers in 3 trials and 0.9% (95% CI: 0.77 to 1.03) with diuretics in 3 trials. Importantly, we found ARBs were less effective in a long time span (95% CI: -1.990 to -0.622) than the first 6 months (95% CI: -0.484 to 0.360).

CONCLUSIONS

This study shows that ARBs improve peripheral endothelial function and are superior to CCBs, β-blockers and diuretics. However, the effect couldn't be maintained for a long time. In addition, there was no significant difference between ARBs and ACEI.

Peroxisome proliferator-activated receptor gamma concentrations in newly diagnosed hypertension patients and the metabolic effects of olmesartan

BACKGROUND AND AIMS

We undertook this study to investigate the effects of olmesartan treatment on PPAR-gamma (PPAR-γ) concentrations and metabolic syndrome (MetS) components in hypertensive (HT) patients.

METHODS

The study included 46 newly diagnosed hypertensive patients and 30 healthy controls. All hypertensive patients were given 40 mg of olmesartan, and they were evaluated weekly in the first month and then twice weekly during follow-up visits. At the end of 3 months, MetS components were assessed and serum PPAR-γ transcription factor concentrations were again measured.

RESULTS

MetS was noted in 80.4% of HT patients. Serum PPAR-γ transcription factor concentration were significantly lower in those with HT compared with the controls (p = 0.005). PPAR-γ concentrations of controls were 1.14-fold higher than hypertensive patients. HDL levels were significantly increased after treatment (p = 0.004), triglyceride, total cholesterol, fasting blood glucose (FBG), and LDL levels were significantly reduced (p <0.05). There was a tendency toward increased PPAR-γ concentrations after treatment, but these were not statistically significant (p = 0.154).

CONCLUSIONS

Olmesartan treatment was found to generate beneficial effects on MetS parameters in HT patients but did not produce any significant increases in serum PPAR-γ transcription factor concentration.

The role of the renin-angiotensin-aldosterone system in obesity-related renal diseases

Obesity is an independent risk factor for the development and progression of chronic kidney disease and one of the emerging reasons for end-stage renal disease owing to its dramatic increase worldwide. Among the potential underlying pathophysiologic mechanisms, activation of the renin-angiotensin-aldosterone-system (RAAS) plays a central role. Increased angiotensin II (AngII) levels also are central in hypertension, dyslipidemia, and insulin resistance, which, taken together with obesity, represent the metabolic syndrome. Increased AngII levels contribute to hyperfiltration, glomerulomegaly, and subsequent focal glomerulosclerosis by altering renal hemodynamics via afferent arteriolar dilation, together with efferent renal arteriolar vasoconstriction as well as by its endocrine and paracrine properties linking the intrarenal and the systemic RAAS, adipose tissue dysfunction, as well as insulin resistance and hypertension. The imbalance between increased AngII levels and the angiotensin converting enzyme 2/Ang (1-7)/Mas receptor axis additionally contributes to renal injury in obesity and its concomitant metabolic disturbances. As shown in several large trials and experimental studies, treatment of obesity by weight loss is associated with an improvement of kidney disease because it also is beneficial in dyslipidemia, hypertension, and diabetes. The most promising data have been seen by RAAS blockade, pointing to the central position of RAAS within obesity, kidney disease, and the metabolic syndrome.

The vascular endothelium in diabetes--a therapeutic target?

Insulin resistance affects the vascular endothelium, and contributes to systemic insulin resistance by directly impairing the actions of insulin to redistribute blood flow as part of its normal actions driving muscle glucose uptake. Impaired vascular function is a component of the insulin resistance syndrome, and is a feature of type 2 diabetes. On this basis, the vascular endothelium has emerged as a therapeutic target where the intent is to improve systemic metabolic state by improving vascular function. We review the available literature presenting studies in humans, evaluating the effects of metabolically targeted and vascular targeted therapies on insulin action and systemic metabolism. Therapies that improve systemic insulin resistance exert strong concurrent effects to improve vascular function and vascular insulin action. RAS-acting agents and statins have widely recognized beneficial effects on vascular function but have not uniformly produced the hoped-for metabolic benefits. These observations support the notion that systemic metabolic benefits can arise from therapies targeted at the endothelium, but improving vascular insulin action does not result from all treatments that improve endothelium-dependent vasodilation. A better understanding of the mechanisms of insulin's actions in the vascular wall will advance our understanding of the specificity of these responses, and allow us to better target the vasculature for metabolic benefits.

Effect of Angiotensin-converting enzyme inhibitors and Angiotensin receptor antagonists in atherosclerosis prevention

Atherosclerosis is a highly complex biological process that has become the scourge of modern civilization. Endothelial dysfunction is the first step in the development of atherosclerosis. The renin-angiotensin-aldosterone system (RAAS) plays an important role in the development of endothelial dysfunction and atherosclerosis. Several studies have shown that in vitro blockade of the RAAS is associated with improvement in markers of endothelial dysfunction and inflammation. Many clinical trials have demonstrated a clear benefit of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) manifested by a reduction of cardiovascular events. These findings suggest that ACEIs and ARBs can play an important role in prevention of atherosclerosis and in the delay of its progression. In this review we focus on the importance of RAAS blockade to prevent or delay progression of atherosclerosis and its impact on reduction of cardiovascular events.

Link between the renin-angiotensin system and insulin resistance: implications for cardiovascular disease

The incidence of metabolic syndrome is rapidly increasing in the United States and worldwide. The metabolic syndrome is a complex metabolic and vascular disorder that is associated with inappropriate activation of the renin-angiotensin-aldosterone system (RAAS) in the cardiovascular (CV) system and increased CV morbidity and mortality. Insulin activation of the phosphatidylinositol-3-kinase (PI3K) pathway promotes nitric oxide (NO) production in the endothelium and glucose uptake in insulin-sensitive tissues. Angiotensin (Ang) II inhibits insulin-mediated PI3K pathway activation, thereby impairing endothelial NO production and Glut-4 translocation in insulin-sensitive tissues, which results in vascular and systemic insulin resistance, respectively. On the other hand, Ang II enhances insulin-mediated activation of the mitogen-activated protein kinase (MAPK) pathway, which leads to vasoconstriction and pathologic vascular cellular growth. Therefore, the interaction of Ang II with insulin signaling is fully operative not only in insulin-sensitive tissues but also in CV tissues, thereby linking insulin resistance and CV disease. This notion is further supported by an increasing number of experimental and clinical studies indicating that pharmacological blockade of RAAS improves insulin sensitivity and endothelial function, as well as reduces the incidence of new-onset diabetes in high-risk patients with CV disease. This article reviews experimental and clinical data elucidating the physiological and pathophysiological role of the interaction between insulin and RAAS in the development of insulin resistance as well as CV disease.

Resistin involved in endothelial dysfunction among preclinical Tibetan male young adults

INTRODUCTION

Resistin, an adipocyte-derived hormone, was found to be linked to metabolic syndrome and insulin resistance over the past decade. There is growing evidence that resistin plays a potential role in endothelial dysfunction. To the best of our knowledge, few studies have been concerned with the effect of resistin on endothelial function in a Tibetan population.

AIMS

To investigate the correlation of resistin and endothelial function among preclinical Tibetan male young adults.

MATERIALS AND METHODS

All participants recruited were young adults between 30 and 40 years old of male gender in Lhasa city. All subjects were native Tibetan. A total of 90 healthy subjects were accepted after excluding hypertension, diabetes, hyperlipidemia or coronary artery disease. The subjects were divided into three groups according to flow-mediated dilation (FMD): lower FMD (group A), intermediate FMD (group B) and higher FMD (group C). Body mass index, systolic blood pressure (SBP), diastolic blood pressure (DBP) and cigarette smoking were evaluated. Venous blood was sampled for the measurement of lipid profile, fasting blood glucose (FBG), fasting insulin (FINS), endothelin-1 (ET-1) and plasma resistin quantitation. The non-invasive vascular endothelial function was evaluated through the measurement of FMD with B-mode ultrasound. The insulin resistance was estimated as homeostatic model assessment of insulin resistance (HOMA-IR) = FINS(mu/L)*FBG(mmol/L)/22.5.

RESULTS

No statistical significance was found between groups in age, smoking, SBP, DBP, fasting insulin, total cholesterol and HOMA-IR (p>0.05). In the lipid profile, high density lipoprotein (HDL) and low density lipoprotein (LDL) cholesterol in group C were better than in groups A and B (p<0.01). Body mass index, which is an indicator for obesity, was much lower in group C than in group A and B (p<0.05 and 0.01 respectively). Comparison of plasma resistin concentrations: group A > group B > group C (p<0.01). Comparison of plasma ET-1 concentrations had a similar result: group A > group B > group C (p<0.05). The multivariate regression analysis showed that total cholesterol (p<0.05), LDL cholesterol (p<0.01), plasma resistin (p<0.01) and plasma ET-1 (p<0.01) were correlated with FMD.

CONCLUSIONS

Resistin is involved in endothelial dysfunction in preclinical male young Tibetan adults.

Effects of losartan on whole body, skeletal muscle and vascular insulin responses in obesity/insulin resistance without hypertension

AIMS

Renin-angiotensin system antagonists have been found to improve glucose metabolism in obese hypertensive and type 2 diabetic subjects. The mechanism of these effects is not well understood. We hypothesized that the angiotensin receptor antagonist losartan would improve insulin-mediated vasodilation, and thereby improve insulin-stimulated glucose uptake in skeletal muscle of insulin-resistant subjects.

METHODS

We studied subjects with obesity and insulin resistance but without hypertension, hypercholesterolaemia or dysglycaemia [age 39.0 ± 9.6 yr (mean ± SD), body mass index (BMI) 33.2 ± 5.9 kg/m(2) , BP 115.8 ± 12.2/70.9 ± 7.2 mmHg, LDL 2.1 ± 0.5 mmol/l]. Subjects were randomized to 12 weeks' double-blind treatment with losartan 100 mg once daily (n = 9) or matching placebo (n = 8). Before and after treatment, under hyperinsulinaemic euglycaemic clamp conditions we measured whole-body insulin-stimulated glucose disposal, insulin-mediated vasodilation, and insulin-stimulated leg glucose uptake by the limb balance technique.

RESULTS

Whole-body insulin-stimulated glucose disposal was not significantly increased by losartan. Insulin-mediated vasodilation was augmented following both treatments [increase in leg vascular conductance: pretreatment 0.7 ± 0.3 l/min/mmHg (losartan, mean ± SEM) and 0.9 ± 0.3 (placebo), posttreatment 1.0 ± 0.4 (losartan) and 1.3 ± 0.6 (placebo)] but not different between treatment groups (p = 0.53). Insulin's action to augment nitric oxide (NO) production and to augment endothelium-dependent vasodilation was also not improved. Leg glucose uptake was not significantly changed by treatments, and not different between groups (p = 0.11).

CONCLUSIONS

These findings argue against the hypothesis that losartan might improve skeletal muscle glucose metabolism by improving insulin-mediated vasodilation in normotensive insulin-resistant obese subjects. The metabolic benefits of angiotensin receptor blockers may require the presence of hypertension in addition to obesity-associated insulin resistance.

The effect of antihypertensive drugs on endothelial function as assessed by flow-mediated vasodilation in hypertensive patients

Endothelial dysfunction is found in hypertensive patients and may serve as a prognostic marker of future cardiovascular events. Endothelial function can be assessed noninvasively by flow-mediated vasodilation (FMD). The goal of this paper is to summarize comprehensively the clinical trials that investigated the effects of antihypertensive drugs on endothelial function assessed by FMD in hypertensive patients. A PubMed-based search found 38 clinical trial papers published from January 1999 to June 2011. Significant improvement of FMD after antihypertensive treatment was shown in 43 of 71 interventions (among 38 clinical trial papers). Angiotensin II receptor blockers and angiotensin converting enzyme inhibitors appeared to improve FMD more than other drug types. Antihypertensive treatment can improve endothelial dysfunction when assessed by FMD, although there are conflicting data that require further research.

Antihypertensive effects exerted by enalapril in mild to moderate hypertension are not associated with changes in the circulating levels of nitric oxide-related markers

PURPOSE

The antihypertensive effects of angiotensin-converting enzyme inhibitors (ACEi) are explained, at least in part, by enhanced bradykinin-dependent nitric oxide (NO) formation and decreased angiotensin II-induced oxidative stress and vasoconstriction. We examined for the first time whether treatment with enalapril increases the plasma levels of markers of NO formation and decreases oxidative stress in mild to moderate hypertensive patients.

METHODS

Eighteen untreated hypertensive patients were treated with enalapril 10 mg/day (n=10) or 20 mg/day (n=8) for 60 days. Eighteen normotensive healthy controls were followed for the same period. Venous blood samples were collected at baseline and after 30/60 days of treatment with enalapril. Plasma NOx (nitrites + nitrates) concentrations were determined by using the Griess reaction. Plasma nitrite and whole blood nitrite concentrations were determined by using an ozone-based chemiluminescence assay. Plasma thiobarbituric acid-reactive species (TBARS) and 8-isoprostane concentrations were determined by a fluorimetric method and by ELISA, respectively.

RESULTS

Treatment with enalapril decreased blood pressure in hypertensive patients. However, we found no significant changes in plasma NOx, nitrite, whole blood nitrite, and in the levels of markers of oxidative stress in both normotensive controls and hypertensive patients treated with enalapril.

CONCLUSIONS

Our data show that enalapril 10-20 mg/day does not affect the concentrations of relevant markers of NO formation or markers of oxidative stress in mild to moderately hypertensive subjects, despite satisfactory blood pressure control. Our findings do not rule out the possibility that ACEi may produce such effects in more severely hypertensive patients treated with higher doses of ACEi.

Effect of telmisartan on selected adipokines, insulin sensitivity, and substrate utilization during insulin-stimulated conditions in patients with metabolic syndrome and impaired fasting glucose

Objective

Telmisartan improves glucose and lipid metabolism in rodents. This study evaluated the effect of telmisartan on insulin sensitivity, substrate utilization, selected plasma adipokines and their expressions in subcutaneous adipose tissue (SAT) in metabolic syndrome.

Design and methods

Twelve patients with impaired fasting glucose completed the double-blind, randomized, crossover trial. Patients received telmisartan (160 mg/day) or placebo for 3 weeks and vice versa with a 2-week washout period. At the end of each period, a hyperinsulinemic euglycemic clamp (HEC) combined with indirect calorimetry was performed. During HEC (0, 30, and 120 min), plasma levels of adipokines were measured and a needle biopsy (0 and 30 min) of SAT was performed.

Results

Fasting plasma glucose was lower after telmisartan compared with placebo (P<0.05). There were no differences in insulin sensitivity and substrate utilization. We found no differences in basal plasma adiponectin, resistin and tumour necrosis factor α (TNFα), but an increase was found in basal leptin, after telmisartan treatment. Insulin-stimulated plasma adiponectin (P<0.05), leptin and resistin (P<0.001) were increased, whereas TNFα was decreased (P<0.05) after telmisartan treatment. Expression of resistin, but not adiponectin, TNFα and leptin was increased after telmisartan treatment.

Conclusions

Despite the decrease in fasting plasma glucose, telmisartan does not improve insulin sensitivity and substrate utilization. Telmisartan increases plasma leptin as well as insulin-stimulated plasma adiponectin, leptin and resistin, and decreases plasma TNFα during HEC. Changes in plasma adipokines cannot be explained by their expressions in SAT. The changes in plasma adipokines might be involved in the metabolic effects of telmisartan in metabolic syndrome.

Role of heme oxygenase in inflammation, insulin-signalling, diabetes and obesity

Diabetes and obesity are chronic conditions associated with elevated oxidative/inflammatory activities with a continuum of tissue insults leading to more severe cardiometabolic and renal complications including myocardial infarction and end-stage-renal damage. A common denominator of these chronic conditions is the enhanced the levels of cytokines like tumour necrosis factor-alpha (TNF-α), interleukin (IL-6), IL-1β and resistin, which in turn activates the c-Jun-N-terminal kinase (JNK) and NF-κB pathways, creating a vicious cycle that exacerbates insulin resistance, type-2 diabetes and related complications. Emerging evidence indicates that heme oxygenase (HO) inducers are endowed with potent anti-diabetic and insulin sensitizing effects besides their ability to suppress immune/inflammatory response. Importantly, the HO system abates inflammation through several mechanisms including the suppression of macrophage-infiltration and abrogation of oxidative/inflammatory transcription factors like NF-κB, JNK and activating protein-1. This review highlights the mechanisms by which the HO system potentiates insulin signalling, with particular emphasis on HO-mediated suppression of oxidative and inflammatory insults. The HO system could be explored in the search for novel remedies against cardiometabolic diseases and their complications.

Fixed-dose manidipine/delapril versus losartan/hydrochlorothiazide in hypertensive patients with type 2 diabetes and microalbuminuria

INTRODUCTION

Patients with diabetes complicated by hypertension and microalbuminuria have elevated cardiovascular risk, and controlling blood pressure in these patients is an urgent clinical priority. The present study aimed to examine the effects of a fixed-dose combination of antihypertensives on blood pressure and microalbuminuria.

METHODS

Patients with type 2 diabetes, mild-to-moderate hypertension (diastolic blood pressure 85-105 mmHg, systolic blood pressure <160 mmHg, and 24-hour mean systolic blood pressure >130 mmHg), and microalbuminuria were randomized to 1 year of doubleblind treatment with fixed-dose manidipine/delapril (n=54) or losartan/hydrochlorothiazide (HCTZ) (n=56).

RESULTS

Blood pressure was significantly reduced at 1 year in both groups (-22.2/-14.6 mmHg and -19.5/-14.3 mmHg, for systolic and diastolic blood pressure respectively, P<0.001 for each), with no significant between-group difference. Reductions in microalbuminuria occurred in both groups, with mean changes at 1 year of -3.9 mg/mmol creatinine (95% CI -5.3, -2.5) for manidipine/delapril (P<0.001 vs. baseline) and -2.7 mg/mmol creatinine (95% CI -4.0, -1.3) for losartan/HCTZ (P<0.001 vs. baseline and P=0.199 between groups). Glycemia over the 1-year study was largely unaffected; the blood glucose concentration was reduced from baseline with manidipine/delapril, although not statistically significant (mean change -0.2 mmol/L, P=0.064). Both treatments were well tolerated, with discontinuation for adverse events for one (1.9%) patient in the manidipine/delapril group and two (3.6%) in the losartan/HCTZ group.

CONCLUSIONS

A fixed-dose manidipine/delapril combination represents a useful addition to the treatment options available to control hypertension complicated by diabetes and microalbuminuria.

Prehypertension: risk stratification and management considerations

Approximately 37% of US adults are prehypertensive; about 31 million have blood pressures in the range of 130-139/85-89 mm Hg. These stage 2 prehypertensives have threefold greater risk for developing hypertension and twofold higher risk for cardiovascular events than normotensives. Lifestyle changes only are recommended for most prehypertensives, but evidence for community-wide effectiveness is limited. Projected numbers needed to treat to prevent a cardiovascular event are similar for stage 2 prehypertension and stage 1 hypertension when both groups are matched for concomitant risk factors. However, no clinical trials document that pharmacotherapy reduces cardiovascular events in stage 2 prehypertension. The Trial of Preventing Hypertension demonstrated that angiotensin receptor blockade safely lowers blood pressure and prevents or delays progression to hypertension in stage 2 prehypertensives. We believe it is reasonable for clinicians to identify stage 2 prehypertensives at high absolute risk for progression to hypertension and cardiovascular events, and to treat them with a renin-angiotensin system blocker when lifestyle changes alone are ineffective.

Comparative effects of N-acetyl-l-cysteine and ramipril on arterial hypertension, insulin resistance, and oxidative stress in chronically glucose-fed rats

Beneficial effects of an antioxidant (N-acetyl-l-cysteine, NAC) and an angiotensin I-converting enzyme (ACE) inhibitor (ramipril) were assessed in a rat model of insulin resistance induced by 10% glucose feeding for 20 weeks. Treatments with NAC (2 g/kg per day) and ramipril (1 mg/kg per day) were initiated at 16 weeks in the drinking fluid. Systolic blood pressure, plasma levels of insulin and glucose, and insulin resistance were significantly higher in rats treated with glucose for 20 weeks. This was associated with a higher production of superoxide anion and NADPH oxidase activity in aorta and liver and with a marked reduction in protein expression of skeletal muscle insulin receptor substrate-1 (IRS-1) in the gastrocnemius muscle. NAC prevented all these alterations. Although ramipril also reversed high blood pressure, it had a lesser effect on insulin resistance (including IRS-1) and blocked superoxide anion production only in aorta. Ramipril, in contrast to NAC, did not reduce NADPH oxidase activity in aorta and liver or plasma levels of 4-hydroxynonenal and malondialdehyde. Results suggest that the inhibition of the oxidative stress in hypertensive and insulin-resistant states contributes to the therapeutic effects of NAC and ramipril. Whereas NAC exerts effective antioxidant activity in multiple tissues, ramipril appears to preferentially target the vasculature.

Blockade of sensory abnormalities and kinin B(1) receptor expression by N-acetyl-L-cysteine and ramipril in a rat model of insulin resistance

Glucose-fed rat is a model of insulin resistance that displays sensory polyneuropathy and hypertension. This study aimed at comparing the beneficial effects of N-acetyl-L-cysteine (NAC, antioxidant) and ramipril (angiotensin-1 converting enzyme inhibitor) on tactile and cold allodynia induced by chronic glucose feeding. Impact of these treatments was also assessed on hypertension, plasma glucose and insulin concentrations, insulin resistance and kinin B(1) receptor expression. Male Wistar rats (50-75 g) were given 10% d-glucose in their drinking water for 11 weeks or tap water (controls). Glucose-fed rats were treated either with NAC (1 g/kg/day, gavage), ramipril (1 mg/kg/day in drinking water) or no drug during the last 5 weeks. Glucose feeding for 6 weeks induced a significant increase in systolic blood pressure and hyperglycaemia which was accompanied by tactile and cold allodynia. At 11 weeks, plasma insulin, insulin resistance (HOMA index), kinin B(1) receptor mRNA in spinal cord and renal cortex and B(1) receptor binding sites in spinal cord were enhanced in glucose-fed rats. NAC and ramipril caused a progressive to complete inhibition of tactile and cold allodynia from 6 to 11 weeks. High systolic blood pressure, hyperinsulinemia, insulin resistance and kinin B(1) receptor expression were also normalized or attenuated in glucose-fed rats by either treatment. Results suggest that chronic treatment with an antioxidant or an ACE inhibitor provides similar beneficial effects on sensory polyneuropathy, hypertension and insulin resistance in glucose-fed rats. Both therapies were associated with a reduction of the expression of the pro-nociceptive kinin B(1) receptor.

Vascular biology of angiotensin and the impact of physical activity

The renin-angiotensin system (RAS) is important for regulating blood pressure and extracellular fluid. The concept of the RAS has recently evolved from a classical systemic endocrine system to an appreciation of local RASs functioning in a paracrine manner, including in the vascular wall. Angiotensin II (AII), the main effector of the RAS, is a potent vasoconstrictor formed by the action of angiotensin-converting enzyme (ACE). ACE is multifunctional and also destroys the endogenous vasodilator bradykinin. A recently discovered novel ACE2 enzyme is responsible for forming a vasodilatory compound, angiotensin 1-7, from AII. Thus, the actions of ACE and ACE2 are antagonistic. Tissue actions of AII are mediated by specific receptors, AT1 and AT2, with AT1 mediating the classical actions. AT1-stimulated vasoconstricton occurs via phospholipase-D-mediated second messenger generation directly, and indirectly via the coupling of AT1 to the prooxidant enzyme NADPH oxidase. Since the vascular NADPH oxidase is a major source of vascular reactive oxygen species generation and is responsible for the breakdown of the vasodilator nitric oxide (NO), there is another potential link between RAS and regulation of vasodilatory pathways. AT2 signaling is antagonistic to AT1 signaling, and results in bradykinin and NO formation. Chronic AII signaling induces vascular dysfunction, whereas pharmacological management of the RAS can not only control blood pressure, but also correct endothelial dysfunction in hypertensives. Exercise training can also improve endothelial function in hypertensives, raising the question of whether there is a potential role for RAS in mediating the vascular effects of exercise training. Recent studies have demonstrated reductions in the expression of NADPH oxidase components in the vascular wall in response to exercise training, thus tempering one of the main cellular effectors of AII, and this is associated with reduced vascular ROS production and enhanced NO bioavailability. Importantly, it has now been demonstrated in human arteries that exercise training also tempers vascular AT1 receptor expression and AII-induced vasoconstriction, while enhancing endothelium-dependent dilation. The signals responsible for these chronic adaptations are not clearly understood, and may include changes in RAS components prompted by acute exercise. ACE genotype may have an effect on physical activity levels and on the cardiovascular responses to exercise training, and the II genotype (compared with ID and DD) is associated with the largest endothelium-dependent dilations in athletes compared with those in sedentary individuals. Thus, the tissue location of the RAS, the complement of ACE/ACE2, the receptor expression of AT1/AT2, and the ACE genotype are all variables that could impact the vascular responses to exercise training, but the responses of most of these variables to regular exercise training and the mechanisms responsible have not been systematically studied.

Effects of losartan and enalapril on high-sensitivity C-reactive protein and total antioxidant in renal transplant recipients with Renin-Angiotensin system polymorphisms

BACKGROUND

As renin-angiotensin system (RAS) activity may affect the severity of oxidative stress and inflammatory markers, we assessed the effects of enalapril (E) and/or losartan (L) on these markers in renal transplant recipients with RAS polymorphisms.

PATIENTS AND METHODS

After determination by PCR of RAS genotypes, consisting of the angiotensin-converting enzymes (ACE I/D), angiotensinogens (AGT M235T) and angiotensin II type 1 receptors (ATR1 A1166C), 76 recipients were recruited randomly and assigned 4 groups. The first (n = 17) and second (n = 24) groups were treated with E (E(+): 10 mg/d) and L (L(+): 50 mg/d) alone, respectively. The third positive control group (n = 17) received E + L (E(+)L(+): 10 mg/d + 50 mg/d) and the fourth negative control group (n = 18) received no medication (E(-):L(-)). High-sensitivity C-reactive protein (hs-CRP) and total antioxidant (TA) inflammatory and antioxidative markers were measured after 2 months. After a 2-week washout period, the E(+) group was changed to L(+) and vice versa in a crossover design. They were followed for another 8 weeks before retesting hs-CRP and TA. A value of P < or = .05 was considered significant.

RESULTS

After 2 and 4 months of treatment with the drug regimen, hs-CRP and TA levels were significantly decreased and consequently increased among the E(+)L(+), L(+) and E(+) groups (P < .05). On analyzing the relationship between RAS polymorphisms and baseline hs-CRP or TA levels, CC genotype of ATR1 showed lower hs-CRP levels (P = .04). However, none of the RAS polymorphisms predicted the antioxidant and anti-inflammatory response rates to the drugs (P > .05).

CONCLUSION

Although hs-CRP was lower in the CC genotype patients of ATR1 polymorphisms E and/or L reduced hs-CRP and increased TA regardless of the RAS genotype.

ACE inhibition and endothelial function: main findings of PERFECT, a sub-study of the EUROPA trial

Background

ACE inhibition results in secondary prevention of coronary artery disease (CAD) through different mechanisms including improvement of endothelial dysfunction. The Perindopril-Function of the Endothelium in Coronary artery disease Trial (PERFECT) evaluated whether long-term administration of perindopril improves endothelial dysfunction.

Methods

PERFECT is a 3-year double blind randomised placebo controlled trial to determine the effect of perindopril 8 mg once daily on brachial artery endothelial function in patients with stable CAD without clinical heart failure. Endothelial function in response to ischaemia was assessed using ultrasound. Primary endpoint was difference in flow-mediated vasodilatation (FMD) assessed at 36 months.

Results

In 20 centers, 333 patients randomly received perindopril or matching placebo. Ischemia-induced FMD was 2.7% (SD 2.6). In the perindopril group FMD went from 2.6% at baseline to 3.3% at 36 months and in the placebo group from 2.8 to 3.0%. Change in FMD after 36 month treatment was 0.55% (95% confidence interval −0.36, 1.47; p = 0.23) higher in perindopril than in placebo group. The rate of change in FMD per 6 months was 0.14% (SE 0.05, p = 0.02) in perindopril and 0.02% (SE 0.05, p = 0.74) in placebo group (0.12% difference in rate of change p = 0.07).

Conclusion

Perindopril resulted in a modest, albeit not statistically significant, improvement in FMD.

Prevention of DNA damage in renal transplantation by losartan and enalapril: the role of renin-angiotensin system polymorphisms

BACKGROUND

In this study the effect of losartan and enalapril on the reduction of DNA damage was evaluated in regard to renin-angiotensin system (RAS) polymorphisms.

METHODS

After determination of genotypes of RAS polymorphism by PCR, 64 renal transplant recipients were randomly allocated to one of four groups: the first and second groups were treated with E (E+: 10 mg/day) and L (L+: 50 mg/day) alone, respectively. The third group received E+L (E+L+: 10 + 50 mg/day), and the forth group received no medication (E-L-). The subjects were followed for 8 weeks. After a 2-week washout period, the E group changed to L and vice versa as a cross-over design. They were followed for another 8 weeks. Before and after treatment, we checked 8-OHdG and malondialdehyde (MDA) as biomarkers of DNA damage and lipid peroxidation, respectively.

RESULTS

8-OHdG levels were significantly decreased after treatment in the E+L+ and L+ groups (P < 0.001, P = 0.001, respectively). Only the TT genotype of AGT had the most antioxidative role regarding the treatment (P = 0.01). We found a remarkable correlation between MDA and DNA damage levels before and after intervention (r = 0.48, P < 0.001; r = 0.35, P = 0.006).

CONCLUSION

The protective effects of L+ and E+L+ on DNA breaks are surprising regarding the RAS polymorphisms.

Comparison of home and office blood pressure in hypertensive patients treated with zofenopril or losartan

In a parallel double-blind multicentre study, 375 hypertensive patients were enrolled and treated with either the angiotensin-converting enzyme inhibitor (ACEI) zofenopril 30 mg once daily (titration 60 mg od) or the angiotensin II type 1 receptor (AT1) antagonist losartan 50 mg od (titration 100 mg od). Patients with mild to moderate hypertension, defined as a diastolic blood pressure (DBP) between 95 and 110 mmHg in the sitting position without other signs of cardiovascular disease were enrolled and treated for 12 weeks. BP was assessed in the clinic, and self-measured by the patients at home during a working day and a holiday, as well as before and at the clinic follow-ups. Systolic (SBP) and DBP were significantly reduced in both treatment groups to a similar extent at the end of the 12-week study. However, the immediate or early reduction of DBP as well as DBP reduction over the first month was significantly greater with zofenopril (p= 0 .01 and p= 0 .003, respectively) compared with losartan treatment. After 3 months of treatment and dose up-titration, clinic BP reductions were similar in both groups. However, more subjects with losartan had used a higher dose step (42.1%) compared with zofenopril (33.1%). Home BP assessments demonstrated that systolic and diastolic pressures were substantially lower than the BP measurements made by sphygmomanometer in the clinic. In particular, assessments 2-3 days before the clinic visits during working days and holidays were characteristically lower, while the measurements during the clinic visits were largely similar to the conventional BP measurements by the doctor. The number and the severity of adverse events, related to the study medications, were largely benign and similar in both groups. The present study demonstrates that zofenopril in clinically recommended doses is at least therapeutically equivalent to losartan treatment, when assessed by conventional sphygmomanometry at the doctor's office or at home by self-measured BP assessments by the patients. Zofenopril however, induces a more rapid initial lowering of BP over the first month of therapy.

Effect of losartan, compared with atenolol, on endothelial function and oxidative stress in patients with type 2 diabetes and hypertension

OBJECTIVE

It has been shown that angiotensin-converting enzyme inhibition or angiotensin receptor blockade may improve endothelial dysfunction, an early manifestation of atherosclerosis, in patients with diabetes. Whether this protective effect is mediated through blood pressure-lowering effects or other specific mechanisms such as a reduction in oxidative stress is not clear. We investigated the influence of losartan, compared with atenolol, on endothelial function and oxidative stress in patients with type 2 diabetes and hypertension.

METHODS

Thirteen patients were included in this randomized, double-blind, crossover study; they received losartan 50 mg twice daily for 4 weeks followed by atenolol 50 mg twice daily or vice versa. Concomitant medication with renin-angiotensin blocking agents or beta-blockers was withdrawn, whereas other medication remained unchanged. At baseline and after each treatment period, flow-mediated dilation of the brachial artery and oxidative stress were measured in serum samples.

RESULTS

Flow-mediated dilation was increased significantly after 4 weeks' treatment with losartan (3.4 +/- 0.44%) compared with atenolol (2.58 +/- 0.42%; P = 0.01). 8-Isoprostanes, a marker of oxidative stress, were significantly reduced in the losartan group compared with baseline (0.039 +/- 0.007 versus 0.067 +/- 0.006 ng/ml; P = 0.01), but did not differ from baseline with atenolol. Glucose, hemoglobin A1c, highly sensitive C-reactive protein, lipids and systolic blood pressure remained unaltered, whereas diastolic blood pressure tended to be lower in the atenolol group.

CONCLUSIONS

This study demonstrates that losartan significantly improved endothelial function in type 2 diabetes patients with hypertension compared with atenolol. This must be independent of the blood pressure-lowering effect of losartan and is probably caused by an antioxidative effect of the angiotensin receptor blocker.

Enalapril and losartan affect lipid peroxidation in renal transplant recipients with renin–angiotensin system polymorphisms

OBJECTIVES

In this study, the effect of enalapril (E) and/or losartan (L) on lipid peroxidation (LPO) is studied in renal transplant recipients (RTRs) with regard to polymorphisms of renin-angiotensin system (RAS).

DESIGN AND METHODS

After determination of genotypes of the angiotensin-converting enzyme (ACE I/D), angiotensinogen (AGT M235T) and angiotensin II type 1 receptor (ATR1 A1166C) by PCR, sixty-four RTRs recruited to four groups randomly: first (13 patients) and second (20 patients) groups were treated with enalapril (E(+): 10 mg/day) and losartan (L(+): 50 mg/day) alone for 2 months, respectively. After 2 weeks as washout period, E group changed to L and vice versa as a cross-over design and they were treated for another 2 months. The third group (13 patients) as positive control received enalapril+losartan (E(+)L(+): 10 mg/day+50 mg/day) for 16 weeks, and the forth group (18 patients) as negative control received no medication (E(-)L(-)). Malondialdehyde (MDA) as LPO marker was measured before and after treatment. In this study, P<0.05 was considered significant.

RESULTS

After 2 months of treatment, MDA level significantly decreased in all of the groups except the E(-)L(-). MDA level in pre- vs. post-intervention for the E(+)L(+), E(+), L(+) and E(-)L(-) groups were as follows: 5.81+/-2.13 nmol/mL vs. 1.61+/-0.80 nmol/mL (P=0.001), 5.10+/-2.05 nmol/mL vs. 1.68+/-1.01 nmol/mL (P=0.003), 5.20+/-1.61 nmol/mL vs. 1.22+/-0.27 nmol/mL (P=0.000) and 5.27+/-2.12 nmol/mL vs. 5.07+/-2.03 nmol/mL (P=0.52), respectively. Also, the same results were found in the end of 16th week. Although patients with DD genotype of ACE had higher MDA (P=0.01) levels, RAS polymorphisms could not predict the antioxidative response rate to the drugs (P>0.05).

CONCLUSIONS

E and/or L reduce MDA regardless of the RAS genotypes.

Long-term prognostic role of flow-mediated dilatation of the brachial artery after acute coronary syndromes without ST elevation

Coronary endothelial vasodilator dysfunction is associated with increased cardiac events; the close relation between coronary vasomotor dysfunction and brachial artery vasoreactivity has been previously described. This study assessed the prognostic value of noninvasively assessed brachial artery vasoreactivity in survivors of acute coronary syndromes without ST-segment elevation. We examined 98 men (63.1 +/- 10.8 years) who were referred to our hospital for acute coronary syndromes without ST-segment elevation. Brachial artery endothelium-dependent flow-mediated dilation (FMD) and endothelium-independent nitrate-mediated dilation were examined in all patients using high-resolution echocardiographic Doppler ultrasound within 24 hours of admission. Plasma malondialdehyde, a marker of oxidative stress, and left ventricular ejection fraction were also assessed. Twenty-seven patients underwent coronary revascularization. Patients were followed for 24.8 +/- 5.9 months. Cardiovascular death, myocardial infarction, stroke, and unstable angina were designated as cardiovascular events (CEs). Twenty CEs were recorded. Kaplan-Meyer analysis showed that patients with FMD <1.9% (tertile 1 of FMD values) were more likely to have CEs than those with FMD >1.9% (log rank 5.29, p = 0.021). Multivariate Cox regression analysis showed that FMD <1.9% predicted CEs with an adjusted hazard ratio of 3.035 (95% confidence interval 1.148 to 8.023, p = 0.025) after adjustment for age, risk factors, troponin T, ejection fraction, revascularization procedures, number of diseased vessels, and medication. In conclusion, endothelium-dependent dilation of the brachial artery is a strong independent predictor of adverse outcome in survivors of acute coronary syndromes without ST-segment elevation.

The vascular endothelium in hypertension

The vascular endothelium plays a fundamental role in the basal and dynamic regulation of the circulation. Thus, it has a crucial role in the pathogenesis of hypertension. A spectrum of vasoactive substances is synthesised in the endothelium; of these, nitric oxide (NO), prostacyclin (PGI2) and endothelin (ET)-1 are the most important. There is a continuous basal release of NO determining the tone of peripheral blood vessels. Systemic inhibition of NO synthesis or scavenging of NO through oxidative stress causes an increase in arterial blood pressure. Also, the renin-angiotensin-aldosterone system has a major role in hypertension as it has a direct vasoconstrictor effect and important interactions with oxygen free radicals and NO. Prostacyclin, in contrast to NO, does not contribute to the maintenance of basal vascular tone of conduit arteries, but its effect on platelets is most important. ET acts as the natural counterpart to endothelium-derived NO and has an arterial blood pressure-raising effect in man. Anti-hypertensive therapy lowers blood pressure and may influence these different mediators, thus influencing endothelial function. In summary, due to its position between the blood pressure and smooth muscle cells responsible for peripheral resistance, the endothelium is thought to be both victim and offender in arterial hypertension. The delicate balance of endothelium-derived factors is disturbed in hypertension. Specific anti-hypertensive and anti-oxidant treatment is able to restore this balance.

Telmisartan improves insulin sensitivity in nondiabetic patients with essential hypertension

Hypertension is a cardiovascular risk factor commonly associated with insulin resistance, the metabolic syndrome, and type 2 diabetes mellitus. Recent in vitro data indicate that certain angiotensin receptor antagonists, for example, telmisartan, activate peroxisome proliferator-activated receptor gamma (PPAR-gamma) and increase adiponectin protein content in adipocytes. By this means, they may improve insulin sensitivity in vivo. To investigate the effect of antihypertensive treatment on insulin sensitivity and fasting adiponectin serum levels, 37 nondiabetic patients with essential hypertension were randomized to receive telmisartan, the calcium channel blocker nisoldipine, or their combination for 6 weeks in a prospective, parallel group study. Fasting serum glucose, insulin, and adiponectin were evaluated before, 3 weeks (low dose), and 6 weeks (high dose) after initiation of treatment. Furthermore, the effect of telmisartan on PPAR-gamma receptor activity was investigated in vitro using a PPAR-gamma reporter gene assay. As reported previously, telmisartan significantly enhanced PPAR-gamma receptor activity in vitro. At baseline, a positive correlation between insulin serum levels and body mass index of investigated subjects was observed, whereas body mass index and serum adiponectin levels were negatively associated. High-dose treatment with telmisartan but not with nisoldipine reduced serum insulin levels as well as the homeostasis model assessment of insulin resistance, but did not affect serum adiponectin levels. In conclusion, in our study cohort of nondiabetic patients with essential hypertension, telmisartan improved insulin sensitivity by mechanisms apparently not involving adiponectin induction. Future studies will demonstrate whether these telmisartan-induced effects may contribute to a blood pressure-independent reduction in cardiovascular morbidity.

The role of statins in endothelial dysfunction in hypertension

PURPOSE OF REVIEW

Hypertension and dyslipidemia frequently coexist, and endothelial dysfunction is associated with the pathophysiology of both atherosclerosis and hypertension. Evidence is convincing for an overlapping role of oxidative stress, renin-angiotensin system activation, and dyslipidemia in the genesis of endothelial dysfunction.

RECENT FINDINGS

Ample experimental and human data suggest that common cellular pathways are involved in the pathogenesis of hypertension, increased vascular resistance, and plaque formation. Multiple interventions such as dietary modification, exercise, antioxidants, and antihypertensive drugs improve endothelial dysfunction in hypertension. Statin drugs are a cornerstone of dyslipidemia therapy. Studies have demonstrated that statins correct endothelial function and vascular stiffening and may be useful in reducing blood pressure to target levels.

SUMMARY

Statins may be a useful adjunct in the treatment of hypertension in patients with dyslipidemia and possibly those with normal cholesterol levels.

Influence of nebivolol and enalapril on metabolic parameters and arterial stiffness in hypertensive type 2 diabetic patients

OBJECTIVE

To compare the effects of a cardioselective beta-blocker (nebivolol) with those of an angiotensin-converting enzyme inhibitor (enalapril) on parameters of insulin sensitivity, peripheral blood flow and arterial stiffness during one extended glucose clamp experiment.

DESIGN

A randomized, double-blind crossover trial, consisting of two 12-week treatment phases separated by a 4-week wash-out phase.

METHODS

Patients with type 2 diabetes and arterial hypertension were randomly assigned to one of two treatment sequences (nebivolol-enalapril, enalapril-nebivolol). Haemodynamic, metabolic and other laboratory measurements were carried out on the first and last day of each treatment period by means of a glucose clamp experiment that also involved the measurement of blood flow and arterial stiffness.

RESULTS

Twelve patients were included in this study, of which two dropped out early. Efficacy parameters were therefore available for 10 patients. There was no significant difference in any of the primary efficacy parameters. Moreover, the effects on blood pressure did not significantly differ between both treatments. Six adverse events happened during treatment with nebivolol compared with two during treatment with enalapril, but only one was regarded as possibly related to the treatment.

CONCLUSIONS

This pilot study shows that the combined measurement of insulin sensitivity, blood flow and arterial stiffness is feasible. Nebivolol and enalapril did not show different effects with regard to these parameters in hypertensive diabetic patients. If these results are confirmed in larger clinical trials, this would argue against the reservations against beta-blockers as drugs of first choice in patients with diabetes because of potential metabolic side-effects.

Targeting the renin-angiotensin system for the reduction of cardiovascular outcomes in hypertension: angiotensin-converting enzyme inhibitors and angiotensin receptor blockers

Agents that counteract the negative impact of the renin-angiotensin-aldosterone system (RAAS) are effective antihypertensives and reduce the risk of developing Type 2 diabetes. Contrary to common perception, angiotensin-converting enzyme inhibitors do not share the apparent benefit of angiotensin II receptor blockers (ARBs) in reducing risk of cardiovascular-disease outcomes, particularly stroke, in randomised clinical trials. RAAS agents, especially ARBs, are well tolerated. Use of ARBs alone or in combination with other classes of antihypertensive agents to lower blood pressure and/or medications to control other conditions (e.g., insulin sensitivity) reduces risk of cardiovascular disease outcomes and Type 2 diabetes with excellent tolerability. Selected issues related to use of RAAS agents as antihypertensive therapies (e.g., Type 2 diabetes, global risk management, multiple drug therapy and coronary heart disease) are addressed.