Nebivolol increases arterial distensibility in vivo

Adrenoceptors and Hypertension

Hypertension is a very prevalent condition associated with high mortality and morbidity, secondary to changes resulting in blood vessels and resultant end-organ damage. Haemodynamic changes, including an initial rise in cardiac output followed by an increase in total peripheral resistance, denote the early changes associated with borderline or stage 1 hypertension, especially in young men. Increased sodium reabsorption leading to kidney damage is another mechanism proposed as one of the initial triggers for essential hypertension. The underlying pathophysiological mechanisms include catecholamine-induced α1- and ß1-adrenoceptor stimulation, and renin-angiotensin-aldosterone system activation leading to endothelial dysfunction which is believed to lead to persistent blood pressure elevation.α1 blockers, α2 agonists, and ß blockers were among the first oral anti-hypertensives. They are no longer first-line therapy after outcome trials did not demonstrate any benefits over and above other agents, despite similar blood pressure reductions. Angiotensin-converting enzyme inhibitors (or angiotensin receptor blockers), calcium channel blockers, and thiazide-like diuretics are now considered the first line of therapy, although adrenoceptor agents still have a role as second- or third-line therapy. The chapter also highlights hypertension in specific medical conditions such as pregnancy, phaeochromocytoma, hyperthyroidism, portal hypertension, pulmonary arterial hypertension, and ocular hypertension, to provide an overview for clinicians and researchers interested in the role of adrenoceptors in the pathophysiology and management of hypertension.

Vascular Aging: Assessment and Intervention

Vascular aging represents a collection of structural and functional changes in a blood vessel with advancing age, including increased stiffness, vascular wall remodeling, loss of angiogenic ability, and endothelium-dependent vasodilation dysfunction. These age-related alterations may occur earlier in those who are at risk for or have cardiovascular diseases, therefore, are defined as early or premature vascular aging. Vascular aging contributes independently to cardio-cerebral vascular diseases (CCVDs). Thus, early diagnosis and interventions targeting vascular aging are of paramount importance in the delay or prevention of CCVDs. Here, we review the direct assessment of vascular aging by examining parameters that reflect changes in structure, function, or their compliance with age including arterial wall thickness and lumen diameter, endothelium-dependent vasodilation, arterial stiffness as well as indirect assessment through pathological studies of biomarkers including endothelial progenitor cell, lymphocytic telomeres, advanced glycation end-products, and C-reactive protein. Further, we evaluate how different types of interventions including lifestyle mediation, such as caloric restriction and salt intake, and treatments for hypertension, diabetes, and hyperlipidemia affect age-related vascular changes. As a single parameter or intervention targets only a certain vascular physiological change, it is recommended to use multiple parameters to evaluate and design intervention approaches accordingly to prevent systemic vascular aging in clinical practices or population-based studies.

Nebivolol is more effective than atenolol for blood pressure variability attenuation and target organ damage prevention in L-NAME hypertensive rats

β-Adrenergic blockers are no longer recommended as first-line therapy due to the reduced cardioprotection of traditional β-blockers compared with other antihypertensive drugs. It is unknown whether third-generation β-blockers share the limitations of traditional β-blockers. The aim of the present study was to compare the effects of nebivolol or atenolol on central and peripheral systolic blood pressure (SBP) and its variability and target organ damage (TOD) in N-nitro-L-arginine methyl ester (L-NAME) hypertensive rats. Male Wistar rats were treated with L-NAME for 8 weeks together with oral administration of nebivolol 30 mg/kg (n = 8), atenolol 90 mg/kg (n = 8), or vehicle (n = 8). The control group was composed of vehicle-treated Wistar rats. SBP and its variability, as well as echocardiographic parameters, were assessed during the last 2 weeks of treatment. Tissue levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and transforming growth factor β (TGF-β), and histopathological parameters were evaluated in the left ventricle and aorta. Nebivolol had a greater ability than atenolol to decrease central SBP and mid-term and short-term blood pressure variability (BPV) in L-NAME rats. Echocardiographic analysis showed that nebivolol was more effective than atenolol on E/A wave ratio normalization. Compared with atenolol treatment, nebivolol had a greater protective effect on different TOD markers, inducing a decrease in collagen deposition and a reduction in the proinflammatory cytokines IL-6 and TNF-α in the left ventricle and aorta. Our findings suggest that the adverse hemodynamic profile and the reduced cardiovascular protection reported with traditional β-blockers must not be carried forward to third-generation β-blockers.

Does vascular stiffness predict white matter hyperintensity burden in ischemic heart disease with preserved ejection fraction?

The survival rate of patients with ischemic heart disease (IHD) is increasing. However, survivors experience increased risk for neurological complications. The mechanisms for this increased risk are unknown. We tested the hypothesis that patients with IHD have greater carotid and cerebrovascular stiffness, and these indexes predict white matter small vessel disease. Fifty participants (age, 40-78 yr), 30 with IHD with preserved ejection fraction and 20 healthy age-matched controls, were studied using ultrasound imaging of the common carotid artery (CCA) and middle cerebral artery (MCA), as well as magnetic resonance imaging (T1, T2-FLAIR), to measure white matter lesion volume (WMLv). Carotid β-stiffness provided the primary measure of peripheral vascular stiffness. Carotid-cerebral pulse wave transit time (ccPWTT) provided a marker of cerebrovascular stiffness. Pulsatility index (PI) and resistive index (RI) of the MCA were calculated as measures of downstream cerebrovascular resistance. When compared with controls, patients with IHD exhibited greater β-stiffness [8.5 ± 3.3 vs. 6.8 ± 2.2 arbitrary units (AU); P = 0.04], MCA PI (1.1 ± 0.20 vs. 0.98 ± 0.18 AU; P = 0.02), and MCA RI (0.66 ± 0.06 vs. 0.62 ± 0.07 AU; P = 0.04). There was no difference in WMLv between IHD and control groups (0.95 ± 1.2 vs. 0.86 ± 1.4 mL; P = 0.81). In pooled patient data, WMLv correlated with both β-stiffness (R = 0.34, P = 0.02) and cerebrovascular ccPWTT (R = -0.43, P = 0.02); however, β-stiffness and ccPWTT were not associated (P = 0.13). In multivariate analysis, WMLv remained independently associated with ccPWTT (P = 0.02) and carotid β-stiffness (P = 0.04). Patients with IHD expressed greater β-stiffness and cerebral microvascular resistance. However, IHD did not increase risk of WMLv or cerebrovascular stiffness. Nonetheless, pooled data indicate that both carotid and cerebrovascular stiffness are independently associated with WMLv.NEW & NOTEWORTHY This study found that patients with ischemic heart disease (IHD) with preserved ejection fraction and normal blood pressures exhibit greater carotid β-stiffness, as well as middle cerebral artery pulsatility and resistive indexes, than controls. White matter lesion volume (WMLv) was not different between vascular pathology groups. Cerebrovascular pulse wave transit time (ccPWTT) and carotid β-stiffness independently associate with WMLv in pooled participant data, suggesting that regardless of heart disease history, ccPWTT and β-stiffness are associated with structural white matter damage.

Real role of β-blockers in regression of left ventricular mass in hypertension patients: Bayesian network meta-analysis

BACKGROUND

Left ventricular hypertrophy (LVH) is commonly present in patients with hypertension (HT). According to the expert consensus document from American, angiotensin-converting enzyme inhibitor (ACEI) and angiotensin receptor blockers (ARBs) were recommended as 1st-line therapeutic drugs. However, none noticed the different efficacy between fat-soluble and selective β1-receptor blockers (FS-β-B) and other β-blockers on regression of LVH before. The aim of this analysis was to compare the efficacy of FS-β-B with the other 4 different classes of antihypertensive drugs (ACEI, ARBs, calcium channel blockers [CCBs], and diuretics) on regression of LVH.

METHODS

Relative trials were identified in the PubMed, Web of Science, OVID EBM Reviews and Cochrane databases, and the relevant papers were examined. We performed both traditional and Bayesian meta-analysis of randomized controlled trials (RCTs) about the regression of LVH. Sensitivity analysis and regression analysis were performed to explore possible sources of heterogeneity. Inconsistency analysis was performed to check whether the analysis of the trials in the network was indeed consistent.

RESULTS

A total of 41 RCTs involving 2566 patients with HT and LVH were included in this analysis. Bayesian network meta-analysis indicated no statistically significant differences between these groups: FS-β-B and ACEI (MD, -7.09; 95% CI, -14.99, 1.27); FS-β-B and ARB (MD, -2.66; 95% Cl, -12.02, 6.31). Although FS-β-B showed greater efficacy when compared with diuretic (MD, 13.04; 95% CI, 3.38, 22.59) or CCB (MD, 10.90; 95% CI, 1.98, 19.49). The probabilities of being among the most efficacious treatments were: FS-β-B (72%), ARB (27%), ACEI (0.01%), CCB (0.00%), and diuretic (0.00%).

CONCLUSION

Evidence from our analysis reveals that FS-β-B have potential to become 1st-line therapeutic drugs in HT and LVH patients. However, the real efficacy of FS-β-B on regression of LVH should be confirmed by further large, high quality trials considering the limitation of the study number.

Therapeutic approaches of uncomplicated arterial hypertension in patients with COPD

The concomitant presence of systemic arterial hypertension and chronic obstructive pulmonary disease (COPD) is frequent. Indeed, arterial hypertension is the most common comorbid disease in COPD patients. Since many antihypertensive drugs can act on airway function the treatment of arterial hypertension in COPD patients appears complex. Moreover, in these patients, a combined therapy is required for the adequate control of blood pressure. Currently, available data are inconsistent and not always comparable. Therefore the aim of this review is to analyze how antihypertensive drugs can affect airway function in order to improve the clinical management of hypertensive patients with COPD. Thiazide diuretics and calcium channel blockers appear the first-choice pharmacological treatment for these patients.

Modifiable risk factors for increased arterial stiffness in outpatient nephrology

Arterial stiffness, as measured by pulse wave velocity (PWV), is an independent predictor of cardiovascular events and mortality. Arterial stiffness increases with age. However, modifiable risk factors such as smoking, BP and salt intake also impact on PWV. The finding of modifiable risk factors may lead to the identification of treatable factors, and, thus, is of interest to practicing nephrologist. We have now studied the prevalence and correlates of arterial stiffness, assessed by PWV, in 191 patients from nephrology outpatient clinics in order to identify modifiable risk factors for arterial stiffness that may in the future guide therapeutic decision-making. PWV was above normal levels for age in 85/191 (44.5%) patients. Multivariate analysis showed that advanced age, systolic BP, diabetes mellitus, serum uric acid and calcium polystyrene sulfonate therapy or calcium-containing medication were independent predictors of PWV. A new parameter, Delta above upper limit of normal PWV (Delta PWV) was defined to decrease the weight of age on PWV values. Delta PWV was calculated as (measured PWV) - (upper limit of the age-adjusted PWV values for the general population). Mean±SD Delta PWV was 0.76±1.60 m/sec. In multivariate analysis, systolic blood pressure, active smoking and calcium polystyrene sulfonate therapy remained independent predictors of higher delta PWV, while age, urinary potassium and beta blocker therapy were independent predictors of lower delta PWV. In conclusion, arterial stiffness was frequent in nephrology outpatients. Systolic blood pressure, smoking, serum uric acid, calcium-containing medications, potassium metabolism and non-use of beta blockers are modifiable factors associated with increased arterial stiffness in Nephrology outpatients.

Differential effects of nebivolol and metoprolol on arterial stiffness, circulating progenitor cells, and oxidative stress

Unlike traditional beta receptor antagonists, nebivolol activates nitric oxide. We hypothesized that therapy with nebivolol compared with metoprolol would improve arterial stiffness, increase levels of circulating progenitor cells (PC), and decrease oxidative stress (OS). In a randomized, double-blind, cross-over study, 30 hypertensive subjects received either once daily nebivolol or metoprolol succinate for 3 months each. Pulse wave velocity and augmentation index were measured using tonometry. Flow cytometry was used to measure circulating PC. OS was measured as plasma aminothiols. Measurements were performed at baseline, and repeated at 3 and 6 months. No significant differences were present between the levels of OS, arterial stiffness, and PC numbers during treatment with metoprolol compared with nebivolol. In subgroup analyses of beta-blocker naïve subjects (n = 19), nebivolol reduced pulse wave velocity significantly compared with metoprolol (-1.4 ± 1.9 vs. -0.1 ± 2.2; P = .005). Both nebivolol and metoprolol increased circulating levels of CD34+/CD133 + PC similarly (P = .05), suggesting improved regenerative capacity.

Arterial stiffness and cardiovascular therapy

The world population is aging and the number of old people is continuously increasing. Arterial structure and function change with age, progressively leading to arterial stiffening. Arterial stiffness is best characterized by measurement of pulse wave velocity (PWV), which is its surrogate marker. It has been shown that PWV could improve cardiovascular event prediction in models that included standard risk factors. Consequently, it might therefore enable better identification of populations at high-risk of cardiovascular morbidity and mortality. The present review is focused on a survey of different pharmacological therapeutic options for decreasing arterial stiffness. The influence of several groups of drugs is described: antihypertensive drugs (angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, calcium channel blockers, beta-blockers, diuretics, and nitrates), statins, peroral antidiabetics, advanced glycation end-products (AGE) cross-link breakers, anti-inflammatory drugs, endothelin-A receptor antagonists, and vasopeptidase inhibitors. All of these have shown some effect in decreasing arterial stiffness. Nevertheless, further studies are needed which should address the influence of arterial stiffness diminishment on major adverse cardiovascular and cerebrovascular events (MACCE).

Hypotensive and antihypertensive potential of 4-[(1-phenyl-1H-pyrazol-4-yl) methyl]1-piperazine carboxylic acid ethyl ester: a piperazine derivative

AIMS

Clinical complaints on the first-line of cardiovascular medications make continuous search for new drugs a necessity. This study evaluated the cardiovascular effects and mechanism of 4-[(1-phenyl-1H-pyrazol-4-yl)methyl]1-piperazine carboxylic acid ethyl ester (LQFM008).

MAIN METHODS

Normotensive male Wistar or spontaneously hypertensive rats (anesthetized or conscious) were used to evaluate the effect of LQFM008 on the mean arterial pressure (MAP), heart rate (HR), arterial blood flow (ABF), arterial vascular conductance (AVC), baroreflex effectiveness index (BI), systolic blood pressure (SBP), diastolic blood pressure (DBP) and vascular function.

KEY FINDINGS

In anesthetized normotensive rats, LQFM008 (7.3, 14.3 or 28.6 μmol/kg, i.v.) reduced MAP (-21.1±2.7; -23.9±4.7 or -32.4±8.3 mmHg, respectively) and AVC (22%, 32% or 38%) in a dose-dependent manner. LQFM008 elicited a temporal reduction in the SBP and DBP without changes to the BI of conscious normotensive rats. In hypertensive rats, LQFM008 (7.3, 14.3 or 28.6 μmol/kg, i.v.) reduced MAP (-2.3±2.6; -29.3±2.7 or -38.4±2.8 mmHg, respectively) and increased HR (1.6±3.7; 15.4±4.9 or 25.5±6.2 bmp, respectively) in a dose-dependent manner. A week of oral administration of LQFM008 47.7 μmol/kg elicited a temporal reduction in SBP of hypertensive rats. Pretreatments with atropine, WAY-100635 or L-NAME blocked the effect of LQFM008. In addition, LQFM008-induced endothelium-dependent vascular relaxation was inhibited by L-NAME.

SIGNIFICANCE

Our findings showed hypotensive, antihypertensive and vasorelaxant effects of LQFM008 and suggest the participation of nitric oxide, 5-HT1A and muscarinic receptors.

Mechanisms of improved aortic stiffness by arotinolol in spontaneously hypertensive rats

OBJECTIVES

This study investigates the effects on aortic stiffness and vasodilation by arotinolol and the underlying mechanisms in spontaneously hypertensive rats (SHR).

METHODS

The vasodilations of rat aortas, renal and mesenteric arteries were evaluated by isometric force recording. Nitric oxide (NO) was measured in human aortic endothelial cells (HAECs) by fluorescent probes. Sixteen-week old SHRs were treated with metoprolol (200 mg·kg-1·d⁻¹), arotinolol (30 mg·kg-1·d⁻¹) for 8 weeks. Central arterial pressure (CAP) and pulse wave velocity (PWV) were evaluated via catheter pressure transducers. Collagen was assessed by immunohistochemistry and biochemistry assay, while endothelial nitric oxide synthase (eNOS) and eNOS phosphorylation (p-eNOS) of HAECs or aortas were analyzed by western blotting.

RESULTS

Arotinolol relaxed vascular rings and the relaxations were attenuated by Nω-nitro-L-arginine methyl ester (L-NAME, NO synthase inhibitor) and the absence of endothelium. Furthermore, arotinolol-induced relaxations were attenuated by 4-aminopyridine (4-AP, Kv channels blocker). Arotinolol produced more nitric oxide compared to metoprolol and increased the expression of p-eNOS in HAECs. These results indicated that arotinolol-induced vasodilation involves endothelium-derived NO and Kv channels. The treatement with arotinolol in 8 weeks, but not metoprolol, markedly decreased CAP and PWV. Biochemistry assay and immunohistochemistry showed that aortic collagen depositions in the arotinolol groups were reduced compared with SHRs with metoprolol. Moreover, eNOS phosphorylation was significantly increased in aortinolol-treated SHR compared with SHRs with metoprolol.

CONCLUSIONS

Arotinolol improves arterial stiffness in SHR, which involved in increasing NO and decreasing collagen contents in large arteries.

Nebivolol attenuates prooxidant and profibrotic mechanisms involving TGF-β and MMPs, and decreases vascular remodeling in renovascular hypertension

Nebivolol and metoprolol are β1-adrenergic receptor blockers with different properties. We hypothesized that nebivolol, but not metoprolol, could attenuate prooxidant and profibrotic mechanisms of hypertension and therefore protect against the vascular remodeling associated with hypertension. Hypertension was induced in male Wistar rats by clipping the left renal artery. Six weeks after surgery, hypertensive and sham rats were treated with nebivolol (10 mg kg(-1) day(-1)) or metoprolol (20 mg kg(-1) day(-1)) for 4 weeks. Systolic blood pressure was monitored weekly. Morphologic changes in the aortic wall were studied in hematoxylin/eosin and picrosirius red sections. Aortic NAD(P)H activity and superoxide production were evaluated by luminescence and dihydroethidium, respectively, and TBARS levels were measured in plasma. Aortic nitrotyrosine staining was evaluated to assess peroxynitrite formation. TGF-β levels and p-ERK 1/2 expression were determined by immunofluorescence and Western blotting, respectively. Matrix metalloproteinase (MMP) activity and expression were determined by in situ zymography, gel zymography, Western blotting, and immunofluorescence, and TIMP-1 was assessed by immunohistochemistry. Both β1-receptor antagonists exerted very similar antihypertensive effects. However, while metoprolol had no significant effects, nebivolol significantly attenuated vascular remodeling and collagen deposition associated with hypertension. Moreover, nebivolol, but not metoprolol, attenuated hypertension-induced increases in aortic NAD(P)H oxidase activity, superoxide production, TBARS concentrations, nitrotyrosine levels, TGF-β upregulation, and MMP-2 and -9 expression/activity. No effects on p-ERK 1/2 and TIMP-1 expression were found. These results show for the first time that nebivolol, but not metoprolol, attenuates prooxidant and profibrotic mechanisms involving TGF-β and MMP-2 and MMP-9, which promote vascular remodeling in hypertension.

Effects of nebivolol and atenolol on central aortic pressure in hypertensive patients: a multicenter, randomized, double-blind study

INTRODUCTION

The main objective was to compare the mean change in augmentation index of hypertensive patients treated with nebivolol or atenolol.

METHODS

Multicenter, double-blind randomized study conducted in six Spanish centers. We enrolled outpatients between the ages of 40 and 65 years with mild or moderate essential hypertension (systolic blood pressure, SBP ≥ 140 mmHg to ≤ 179 mmHg and diastolic blood pressure, DBP ≥ 90 mmHg to ≤ 109 mmHg after a 2-week run-in placebo period). Patients received nebivolol 5 mg or atenolol 50 mg once daily. At week 3, atenolol could be titrated up to 100 mg qd for non-responders. Additionally, patients not achieving normal blood pressure after 6 weeks could be treated with 25 mg hydrochlorothiazide. Follow-up visits were at 3, 6 and 10 weeks.

RESULTS

The final study population of 138 patients (58% men; median age 52.6 years, range 40-67 years) was randomized into two groups of 69 patients each. Baseline characteristics of the two groups were similar. At the screening visit, 69% presented with mild hypertension. Nebivolol modified the mean augmentation index to a lesser extent than atenolol after 10 weeks (mean difference 3.1%, 95% CI 0.55-5.69; p = 0.027). A higher proportion of patients in the atenolol group required a diuretic. Reductions in central aortic pressure and peripheral arterial pressure were similar for both treatment groups.

CONCLUSIONS

The study confirms that nebivolol produces a less pronounced impact on augmentation index than atenolol.

Increased night heart rate is associated with worse large artery elasticity in chronic kidney disease patients

BACKGROUND

Chronic kidney disease (CKD) is associated with high overall and cardiovascular mortality. Numerous studies have reported that increased heart rate is a risk factor for all-cause mortality. We investigated the link between sleep heart rate and artery stiffness in CKD patients.

METHODS

In a cross-sectional study, we enrolled 100 prevalent Chinese CKD patients (55 males, aged 52.5 ± 16.40 years). Heart rate was measured with an automatic system. Arterial stiffness was evaluated by using a calibrated tonometer.

RESULTS

Large artery elasticity index (LAEI) was positively correlated with body mass index and hemoglobin but negatively associated with age and systolic blood pressure. Furthermore, LAEI was negatively associated with glomerular filtration rate (GFR) and sleep heart rate. In multivariate regression, LAEI was independently predicted by SBP, BMI, age, sleep heart rate, and gender. Adjusted R (2) of the model was 0.486.

CONCLUSION

Elevated sleep heart rate is significantly associated with increased arterial stiffness in CKD patients. Further investigation is needed to explore the potential benefits of sleep heart rate lowering therapy in this patient group.

The effects of acute beta-adrenergic blockade on aortic wave reflection in postmenopausal women

BACKGROUND Acute beta-adrenergic blockade increases aortic-wave reflection in young women. However, it is not known whether this effect extends to postmenopausal women. We therefore examined the effect of systemic beta-adrenergic blockade on aortic wave reflection in 14 postmenopausal women with a mean age of 58±2 years. METHODS Aortic pressure waveforms were synthesized noninvasively from high-fidelity radial pressure waveforms obtained through applanation tonometry before and during systemic beta-blockade with propranolol given in a bolus dose of 0.25mg/kg, followed by a continuous infusion at 0.004mg/kg/min. To further examine the effects of acute beta-blockade on aortic-wave reflection in postmenopausal women, we compared the changes in hemodynamics and indices of aortic-wave reflection with published data from a previous study with a protocol identical to that in the present study but which involved young women. RESULTS Acute beta-blockade increased the aortic augmentation index (AIx) in postmenopausal women (32±2% vs. 35±2%, P < 0.01). However, AIx adjusted for a heart rate of 75 bpm (AIx75) was unchanged (25±2% vs. 24±2%, P > 0.05). The changes in AIx, AIx75, and the amplitude of reflected waves (augmented aortic pressure) during beta-blockade were all substantially smaller in postmenopausal women than in their younger counterparts (P < 0.05). Conclusions As compared with those in our previously published study involving young women, indices of aortic-wave reflection were significantly less affected by acute systemic beta-adrenergic blockade in the postmenopausal women in the present study. Taken together, our data suggest that the negative effects (i.e. increased aortic wave reflection) of nonselective beta-adrenergic blockade are less pronounced in postmenopausal than in young women.

Nitric oxide synthases in heart failure

SIGNIFICANCE

The regulation of myocardial function by constitutive nitric oxide synthases (NOS) is important for the maintenance of myocardial Ca(2+) homeostasis, relaxation and distensibility, and protection from arrhythmia and abnormal stress stimuli. However, sustained insults such as diabetes, hypertension, hemodynamic overload, and atrial fibrillation lead to dysfunctional NOS activity with superoxide produced instead of NO and worse pathophysiology.

RECENT ADVANCES

Major strides in understanding the role of normal and abnormal constitutive NOS in the heart have revealed molecular targets by which NO modulates myocyte function and morphology, the role and nature of post-translational modifications of NOS, and factors controlling nitroso-redox balance. Localized and differential signaling from NOS1 (neuronal) versus NOS3 (endothelial) isoforms are being identified, as are methods to restore NOS function in heart disease.

CRITICAL ISSUES

Abnormal NOS signaling plays a key role in many cardiac disorders, while targeted modulation may potentially reverse this pathogenic source of oxidative stress.

FUTURE DIRECTIONS

Improvements in the clinical translation of potent modulators of NOS function/dysfunction may ultimately provide a powerful new treatment for many hearts diseases that are fueled by nitroso-redox imbalance.

Efficacy and tolerability of nebivolol: does age matter? A retrospective analysis of three randomized, placebo-controlled trials in stage I-II hypertension

OBJECTIVES

This retrospective analysis examined the efficacy and tolerability of nebivolol, a ß(1)-selective, vasodilatory β-blocker, in four different age groups of patients with hypertension.

METHODS

Data were pooled from three 12-week, randomized, placebo-controlled trials (placebo, n = 205; nebivolol [1.25-30/40 mg/day], n = 1811) and stratified into age quartiles (Group 1: 22-46 years; Group 2: 47-53 years; Group 3: 54-62 years; Group 4: 63-84 years). Only patients treated with placebo and the three commonly used nebivolol dosages (5, 10, and 20 mg/day) are presented. Baseline-to-endpoint changes in trough sitting diastolic blood pressure (DBP), systolic blood pressure (SBP), and heart rate (HR) were analyzed for each age quartile using an analysis of covariance (ANCOVA) model. Tolerability was assessed by means of adverse event (AE) rates.

RESULTS

The analysis comprised 205 placebo-treated patients and 1380 patients treated with nebivolol dosages of 5, 10, or 20 mg/day. Older age was associated with higher SBP values at baseline. In all age groups, each of the three most frequently used nebivolol dosages significantly reduced DBP, compared with placebo (-9.1 to -11.8 mmHg versus -3.4 to -5.9 mmHg; p ≤ 0.008 overall). For SBP, a statistically significant effect versus placebo was observed for all dosages and age groups except for 5 and 10 mg/day in Group 4. Within each group, treatment with nebivolol (all three dosages) and placebo resulted in similar AE rates (nebivolol: 26.1-36.6%; placebo: 36.2-42.6%) and AE-related discontinuation rates (1.8-3.8% versus 0-4.3%). In each age group, there were no significant nebivolol-placebo differences in the rates of patients who experienced clinically significant changes or abnormal endpoint levels of metabolic parameters.

CONCLUSIONS

This retrospective analysis suggests that nebivolol monotherapy is efficacious and well tolerated across various age groups, with the efficacy in reducing SBP somewhat diminishing in patients over 62 years of age.

Vascular ageing: main symptoms and mechanisms

The authors discuss major structural and functional vascular changes accompanying ageing, the mechanisms of their development, and potential methods of their correction.

Effect of beta-1-blocker, nebivolol, on central aortic pressure and arterial stiffness in patients with essential hypertension

INTRODUCTION

Blood pressure (BP) reduction is the major determinant of benefit provided by antihypertensive treatment. Although different drugs reduce peripheral BP to some extent, there may be a significant difference in their effect on central BP reduction. It has been shown that beta-blockers are efficient in reducing peripheral, but not central BP. This study was done to assess the effect of beta-1-blocker, nebivolol, in patients with essential hypertension on central aortic pressures and arterial stiffness.

MATERIALS AND METHODS

In this single arm, open-labeled study, 13 patients were given nebivolol, 5 mg orally once daily for 15 days. Primary outcome was change in central aortic pressure, and other measures of efficacy included changes in brachial BP, augmentation index (AIx%), AIx%@75 HR, augmentation pressure (AP), heart rate (HR), and carotid femoral pulse wave velocity (PWVcf).

RESULTS

Nebivolol 5 mg significantly reduced central aortic pressures [systolic BP, 131.5-111.6 mmHg; diastolic BP, 96.3-81.7 mmHg; Mean Arterial Pressure (MAP), 111.3-94.0 mmHg (all P<0.0001), and Pulse Pressure (PP), 35.2-29.7 mmHg (P<0.01)]. AIx%@75 HR reduced from 29 to 21.6 (P<0.001) and PWVcf reduced from 8.6 to 7.2 m/s (P<0.001). One subject was lost to followup.

CONCLUSION

Nebivolol 5 mg demonstrated antihypertensive efficacy in patients with essential hypertension by reducing not only peripheral brachial pressures, but also significantly reducing central aortic pressures, augmentation index, and carotid femoral pulse wave velocity, which is the marker of arterial stiffness.

Nebivolol and metoprolol: long-term effects on inflammation and oxidative stress in essential hypertension

Arterial hypertension is characterised by increased oxidative stress and inflammation, which are associated with further cardiovascular risk. The aim of our study was to investigate the long-term effects of nebivolol and metoprolol succinate on oxidative stress, and on inflammatory and pro-inflammatory markers in patients with hypertension. Eighty patients with never-treated mild-to-moderate essential hypertension, aged 30-65 years, were randomised to a 5 mg daily dose of nebivolol or a 50-100 mg daily dose of metoprolol succinate. Brachial blood pressure, plasma oxidized LDL (oxLDL), interleukin-6 (IL-6), high-sensitivity C-reactive protein (hsCRP), fibrinogen, intercellular adhesion molecule-1 (ICAM-1), asymmetric dimethylarginine (ADMA), and urine 8-isoprostane levels were measured before and after 1 year of treatment. Nebivolol and metoprolol reduced equally significantly brachial blood pressure. The oxLDL was significantly reduced in both groups (p < 0.01 and for both drugs), but only nebivolol reduced 8-isoprostanes (p = 0.01). In the metoprolol group, change in oxLDL levels correlated with change in systolic blood pressure (r = 0.45; p < 0.01) and pulse pressure (r = 0.47; p < 0.01). Both metoprolol and nebivolol reduced ICAM-1 (p < 0.01). There was no change in IL-6, hsCRP, fibrinogen, or ADMA levels in either group. These data suggest that in long-term antihypertensive treatment both the cardioselective beta blocker metoprolol succinate and the vasodilating beta blocker nebivolol have inflammation-related effects but only nebivolol has a favourable blood pressure-independent effect on oxidative stress.

Nebivolol: an endothelium-friendly selective β1-adrenoceptor blocker

Nebivolol is a highly selective β1-adrenoceptor blocker, which also stimulates endothelial nitric oxide synthase and scavenges reactive oxygen species (ROS). These characteristics endow nebivolol, compared with conventional β-blockers, with a favorable hemodynamic profile for the treatment of hypertension, chronic heart failure, and possibly other cardiovascular diseases. Nebivolol is a racemic mixture of d- and l-isomers. Its β1-antagonistic properties reside primarily with d-nebivolol although both isomers are capable of increasing the release of NO from the endothelium after binding to β2- or β3-adrenergic receptors. The latter action results in vasodilatation and reduced vascular resistance. Nebivolol also scavenges ROS in a receptor-independent manner by direct interaction with free radicals. By scavenging ROS nebivolol not only reduces oxidant stress but also augments NO bioavailability. The endothelial nitric oxide synthase -stimulating and ROS scavenging effects of nebivolol act synergistically to provide cardiovascular protection in addition to its β1-antagonistic action.

Nebivolol-induced vasodilation of renal afferent arterioles involves β3-adrenergic receptor and nitric oxide synthase activation

Nebivolol is a β(1)-adrenergic blocker that also elicits renal vasodilation and increases the glomerular filtration rate (GFR). However, its direct actions on the renal microvasculature and vasodilator mechanism have not been established. We used the in vitro blood-perfused juxtamedullary nephron technique to determine the vasodilator effects of nebivolol and to test the hypothesis that nebivolol induces vasodilation of renal afferent arterioles via an nitric oxide synthase (NOS)/nitric oxide (NO)/soluble guanylate cyclase (sGC)/cGMP pathway and the afferent arteriolar vasodilation effect may be mediated through the release of NO by activation of NOS via a β(3)-adrenoceptor-dependent mechanism. Juxtamedullary nephrons were superfused with nebivolol either alone or combined with the sGC inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) or the NOS inhibitor N(ω)-nitro-l-arginine (l-NNA) or the β-blockers metoprolol (β(1)), butoxamine (β(2)), and SR59230A (β(3)). Nebivolol (100 μmol/l) markedly increased afferent and efferent arteriolar diameters by 18.9 ± 3.0 and 15.8 ± 1.8%. Pretreatment with l-NNA (1,000 μmol/l) or ODQ (10 μmol/l) decreased afferent vasodilator diameters and prevented the vasodilator effects of nebivolol (2.0 ± 0.2 and 2.4 ± 0.6%). Metoprolol did not elicit significant changes in afferent vasodilator diameters and did not prevent the effects of nebivolol to vasodilate afferent arterioles. However, treatment with SR59230A, but not butoxamine, markedly attenuated the vasodilation responses to nebivolol. Using a monoclonal antibody to β(3)-receptors revealed predominant immunostaining on vascular and glomerular endothelial cells. These data indicate that nebivolol vasodilates both afferent and efferent arterioles and that the afferent vasodilator effect is via a mechanism that is independent of β(1)-receptors but is predominantly mediated via a NOS/NO/sGC/cGMP-dependent mechanisms initiated by activation of endothelial β(3)-receptors.

Nebivolol: impact on cardiac and endothelial function and clinical utility

Endothelial dysfunction is a systemic pathological state of the endothelium characterized by a reduction in the bioavailability of vasodilators, essentially nitric oxide, leading to impaired endothelium-dependent vasodilation, as well as disarrangement in vascular wall metabolism and function. One of the key factors in endothelial dysfunction is overproduction of reactive oxygen species which participate in the development of hypertension, atherosclerosis, diabetes, cardiac hypertrophy, heart failure, ischemia-reperfusion injury, and stroke. Because impaired endothelial activity is believed to have a major causal role in the pathophysiology of vascular disease, hypertension, and heart failure, therapeutic agents which modify this condition are of clinical interest. Nebivolol is a third-generation β-blocker with high selectivity for β1-adrenergic receptors and causes vasodilation by interaction with the endothelial L-arginine/ nitric oxide pathway. This dual mechanism of action underscores several hemodynamic qualities of nebivolol, which include reductions in heart rate and blood pressure and improvements in systolic and diastolic function. Although nebivolol reduces blood pressure to a degree similar to that of conventional β-blockers and other types of antihypertensive drugs, it may have advantages in populations with difficult-to-treat hypertension, such as patients with heart failure along with other comorbidities, like diabetes and obesity, and elderly patients in whom nitric oxide-mediated endothelial dysfunction may be more pronounced. Furthermore, recent data indicate that nebivolol appears to be a cost-effective treatment for elderly patients with heart failure compared with standard care. Thus, nebivolol is an effective and well tolerated agent with benefits above those of traditional β-blockers due to its influence on nitric oxide release, which give it singular hemodynamic effects, cardioprotective activity, and a good tolerability profile. This paper reviews the pharmacology structure and properties of nebivolol, focusing on endothelial dysfunction, clinical utility, comparative efficacy, side effects, and quality of life in general with respect to the other antihypertensive agents.

Heart rate reduction as a therapeutic goal: focus on primary prevention

Recently published studies have demonstrated a direct link between heart rate (HR) and prognosis across various populations and clinical groups, including elderly people, patients with arterial hypertension, myocardial infarction, and coronary artery stenting, overweight patients, or even young people with relatively low cardiovascular risk levels. HR is considered as an additional independent risk factor (RF) of cardiovascular disease (CVD). However, thus far, pharmaceutical HR reduction has been demonstrated to improve prognosis only in patients with coronary heart disease or chronic heart failure. The results in CVD-free patients have been contradictory. The review discusses the potential of different HR-reducing therapeutic regimens, as a part of primary CVD prevention.

β-blockade: benefits beyond blood pressure reduction?

Hypertension is a major cardiovascular (CV) risk factor, but several other common conditions, including chronic obstructive pulmonary disease (COPD), osteoporosis, and peripheral arterial disease (PAD), have been shown to independently increase the risk of CV events and death. The physiological basis for an increased CV risk in those conditions probably lies in the augmentations of oxidative stress, endothelial dysfunction, systemic inflammation, and arterial stiffness, which all are also hallmarks of hypertension. β-Blockers have been used for the treatment of hypertension for more than 40 years, but a number of meta-analyses have demonstrated that treatment with these agents may be associated with an increased risk of CV events and mortality. However, the majority of primary prevention β-blocker trials employed atenolol, an earlier-generation β(1) -selective blocker whose mechanism of action is based on a reduction of cardiac output. Available evidence suggests that vasodilatory β-blockers may be free of the deleterious effects of atenolol. The purpose of this review is to summarize pathophysiologic mechanisms thought to be responsible for the increased CV risk associated with COPD, osteoporosis, and PAD, and examine the possible benefits of vasodilatory β-blockade in those conditions. Our examination focused on nebivolol, a β(1) -selective agent with vasodilatory effects most likely mediated via β(3) activation.

The role of vasodilating β-blockers in patients with complicated hypertension: focus on nebivolol

Despite their proven mortality and morbidity outcomes benefits, β-blockers remain substantially underused in patients with cardiac conditions. Reluctance to prescribe β-blockers may be owing to concerns about tolerability with the traditional drugs in this class. β-blockers with vasodilatory properties, such as carvedilol and nebivolol, may overcome the tolerability and metabolic issues associated with traditional β-blockers. Because endothelial dysfunction, the pathophysiologic hallmark of hypertension, may be heightened in populations with difficult-totreat hypertension (e.g., elderly patients, African American patients), a vasodilating β-blocker may be a particularly appropriate choice for these patient groups.

Pharmacological modulation of arterial stiffness

Arterial stiffness has emerged as an important marker of cardiovascular risk in various populations and reflects the cumulative effect of cardiovascular risk factors on large arteries, which in turn is modulated by genetic background. Arterial stiffness is determined by the composition of the arterial wall and the arrangement of these components, and can be studied in humans non-invasively. Age and distending pressure are two major factors influencing large artery stiffness. Change in arterial stiffness with drugs is an important endpoint in clinical trials, although evidence for arterial stiffness as a therapeutic target still needs to be confirmed. Drugs that independently affect arterial stiffness include antihypertensive drugs, mostly blockers of the renin-angiotensin-aldosterone system, hormone replacement therapy and some antidiabetic drugs such as glitazones. While the quest continues for 'de-stiffening drugs', so far only advanced glycation endproduct cross-link breakers have shown promise.

Acute β-adrenergic blockade increases aortic wave reflection in young men and women: differing mechanisms between sexes

Acute β-adrenergic blockade increases aortic wave reflection; however, the mechanisms remain unclear. Evidence suggests that β-adrenergic receptor sensitivity in the peripheral vasculature differs between sexes. Therefore, the goal of this study was to examine whether β-adrenergic blockade alters aortic wave reflection to a similar extent in young men and women. In 31 subjects (16 men and 15 women; 26±1 years) noninvasive aortic pressure waveforms were synthesized from high-fidelity radial pressure waveforms via applanation tonometry before and during systemic β-blockade (0.25 mg/kg bolus, followed by 0.004 mg/kg per minute of continuous infusion of propranolol). β-Blockade increased aortic augmentation index and wave reflection amplitude (aortic augmented pressure) in both sexes (P<0.01). Although the increase in augmentation index was not significantly different between sexes (7.5±1.1% versus 4.6±1.5%; P=0.07), the increase in aortic augmented pressure was greater in women compared with men (2.8±0.5 versus 1.4±0.5 mm Hg; P<0.05). Aortic augmentation index adjusted for a heart rate of 75 bp increased in women (4.1±1.1%; P<0.05) after β-blockade, whereas it was unchanged in men (0.6±1.3%; P=0.33). Moreover, the change in aortic augmentation index was inversely associated with the change in heart rate only in men (r=-0.54; P<0.05). Our data suggest that aortic wave reflection is increased to a greater extent in women after systemic β-blockade, and enhanced aortic wave reflection appears to be mediated by a reduced heart rate in men, whereas the mechanism is unclear in women.

The role of vasodilating beta-blockers in patients with complicated hypertension: focus on nebivolol

Despite their proven mortality and morbidity outcomes benefits, beta-blockers remain substantially underused in patients with cardiac conditions. Reluctance to prescribe beta-blockers may be owing to concerns about tolerability with the traditional drugs in this class. Beta-blockers with vasodilatory properties, such as carvedilol and nebivolol, may overcome the tolerability and metabolic issues associated with traditional beta-blockers. Because endothelial dysfunction, the pathophysiologic hallmark of hypertension, may be heightened in populations with difficult-to-treat hypertension (e.g., elderly patients, African American patients), a vasodilating beta-blocker may be a particularly appropriate choice for these patient groups.

[Advantages of vasodilating beta-blockers in congestive heart failure]

Beta-blockers play a pivotal role in the treatment of chronic systolic heart failure. However, the pharmacological family of beta-blockers is inhomogeneous regarding their pharmacological properties and their clinical effects can differ substantially according to different pharmacological properties. Because of vasodilator effects, the third generation of beta-blockers has additional potential across the cardiovascular diseases, from hypertension to heart failure. Nebivololol has both high selectivity for beta1-adrenergic receptors, no intrinsic sympathetic activity and ability to stimulate endothelial nitric oxide production. Such properties result in specific hemodynamic effects compared with others beta-blockers. Such properties also result in both high tolerability and positive metabolic effects which are crucial in high-risk groups. In the SENIORS trial, nebivolol demonstrated its efficacy and high tolerability in elderly patients with chronic heart failure irrespective of the left ventricular ejection fraction. More clinical trials would be useful to exhibit specific benefits of nebivolol in other high-risk groups of patients.

Short-term treatment with a beta-blocker with vasodilative capacities improves intrarenal endothelial function in experimental renal failure

AIMS

In patients with renal disease the cardiovascular risk is greatly increased, and endothelial dysfunction is assumed to play a pivotal role in this process. Therefore we compared treatment effects of a beta-blocker with additional vasodilatory capacities (nebivolol) and a beta-blocker lacking these actions (metoprolol) on intrarenal and coronary vascular function in a rat model of renal failure with hypertension.

MAIN METHODS

Renal failure was induced by 5/6-nephrectomy (Nx) and analyzed after 4 weeks in Wistar rats. Untreated Nx, Nx/nebivolol 6 mg/d (Nx-Nebi); Nx/metoprolol 60 mg/d (Nx-Meto) and sham-operated (Sham) animals were studied. Isolated small renal and coronary arteries were investigated for endothelium-dependent relaxation to acetylcholine (ACh) and for the contribution of the endothelial mediators NO and endothelium-derived hyperpolarizing factor (EDHF).

KEY FINDINGS

Systolic blood pressure (SBP) was significantly increased in Nx, Nx-Nebi, and Nx-Meto (168+/-5, 153+/-3, and 162+/-6 mmHg) compared to Sham (138+/-3 mmHg, p<0.05, respectively). The increase in albuminuria of Nx (120-fold vs. Sham, p<0.0001) was almost (-85%) normalized by nebivolol compared to Sham (p<0.05), whereas metoprolol induced no significant effect. Renal arteries showed significantly increased Ach-relaxation in Nx and Nx-Nebi (Emax 86+/-4% and 76+/-7%, p<0.05) due to an increase in EDHF-mediated dilation (Emax_EDHF 78+/-7% and 73+/-6%) compared to Sham (Emax 54+/-4% and Emax_EDHF 44+/-6%) and Nx-Meto (Emax 42+/-12% and Emax_EDHF 18+/-5%). ACh-relaxation in coronary arteries was similar between groups but the contribution of NO (relative to EDHF) was strongly increased by nebivolol.

SIGNIFICANCE

The present findings offer an explanation of the nephroprotective effect of intrarenal endothelial function in renal failure.

Arterial stiffness, hypertension, and rational use of nebivolol

Arterial stiffness plays a key role in the pathophysiology of the cardiovascular system. Some indices of arterial stiffness (pulse wave velocity, augmentation index, characteristics of central blood pressure waveform) may be presently calculated and evaluated in the clinical setting. Age and blood pressure are the two major clinical determinants of increased arterial stiffness, while molecular determinants of arterial stiffness are related to fibrotic components of the extracellular matrix, mainly elastin, collagen and fibronectin. Increased arterial stiffness has been consistently observed in conditions such as hypertension, dyslipidemia and diabetes. Arterial stiffness evaluated by means of carotid-femoral pulse wave velocity yielded prognostic significance beyond and above traditional risk factors. A more favorable effect of calcium channel blockers, diuretics and ACE inhibitors compared with β-blockers on indices of arterial stiffness was observed in several studies. It is conceivable that newer β-blockers with additional vasodilating properties, such as nebivolol, which has favorable effects on carbohydrate and lipid metabolism, as well as on endothelial function and on oxidative stress, may have favorable effects on arterial stiffness, compared with atenolol. In fact, in recent studies, nebivolol was demonstrated to improve artery stiffness to a greater extent than older β-blockers. Because endothelial dysfunction and increased arterial stiffness play an important role in the early atherosclerotic processes and are associated with poor outcomes and increased mortality, independently of blood pressure, the ability of nebivolol to enhance release of endothelium-derived nitric oxide, and consequently improve endothelial function and arterial stiffness, may have significant clinical implications for the use of this agent in the treatment of hypertension and cardiovascular diseases.

Rationale and design of a trial evaluating the effects of losartan vs. nebivolol vs. the association of both on the progression of aortic root dilation in Marfan syndrome with FBN1 gene mutations

BACKGROUND

The major clinical problem of Marfan syndrome (MFS) is the aortic root aneurysm, with risk of dissection when the root diameter approximates 5 cm. In MFS, a key molecule, transforming growth factor-beta (TGF-beta), normally bound to the extracellular matrix, is free and activated. In an experimental setting, TGF-beta blockade prevents the aortic root structural damage and dilatation. The angiotensin receptor 1 blockers (sartanics) exert an anti-TGF-beta effect; trials are now ongoing for evaluating the effect of losartan compared with atenolol in MFS. beta-Adrenergic blockers are the drugs most commonly used in MFS. The third-generation beta-adrenergic blocker nebivolol retains the beta-adrenergic blocker effects on heart rate and further exerts antistiffness effects, typically increased in MFS.

METHODS

The open-label phase III study will include 291 patients with MFS and proven FBN1 gene mutations, with aortic root dilation (z-score > or =2.5). The patients will be randomized to nebivolol, losartan and the combination of the two drugs. The primary end point is the comparative evaluation of the effects of losartan, nebivolol and the association of both on the progression of aortic root growth rate. Secondary end points include the pharmacokinetics of the two drugs, comparative evaluation of serum levels of total and active TGF-beta, quantitative assessment of the expression of the mutated gene (FBN1, both 5' and 3'), pharmacogenetic bases of drug responsiveness. The quality of life evaluation in the three groups will be assessed. Statistical evaluation includes an interim analysis at month 24 and conclusive analyses at month 48.

CONCLUSION

The present study will add information about pharmacological therapy in MFS, supporting the new application of angiotensin receptor 1 blockers and finding beta-adrenergic blockers that may give more specific effects. Moreover, the study will further deepen understanding of the pathogenetic mechanisms that are active in Marfan syndrome through the pharmacogenomic and transcriptomic mechanisms that may explain MFS phenotype variability.

Nebivolol: a highly selective beta1-adrenergic receptor blocker that causes vasodilation by increasing nitric oxide

Nebivolol (Bystolic) is a cardioselective beta 1 (beta(1))-adrenergic receptor blocker with endothelium-dependent vasodilating properties. The endothelium-dependent relaxation induced by nebivolol is blocked by inhibitors of nitric oxide synthase (NOS) and guanylate cyclase. Nebivolol also increases in vitro and in vivo nitric oxide (NO), which is an essential signaling molecule involved in the maintenance of cardiovascular homeostasis. This review summarizes the data involving nebivolol and NO bioavailability. Endothelium-dependent relaxation of blood vessels, which is impaired in hypertensive animals and humans, is reversed by nebivolol treatment. Animals exhibiting endothelial dysfunction also show an improvement in NO-cyclic guanosine monophosphate (cGMP) signaling and an increase in NO bioavailability when treated with nebivolol. When blood vessel and cultured endothelial cells from hypertensive animals are treated with nebivolol, there is a decrease in superoxide production and an increase in the expression and activity of endothelial NOS (eNOS). As a result of the increased bioavailability of NO, nebivolol also increases in vivo arterial distensibility, glomerular filtration rate, and renal plasma flow. In normotensive volunteers, nebivolol infusion increases the forearm blood flow, an effect that is blocked by inhibitors of NOS and restored by the NOS substrate, L-arginine. In hypertensive patients, chronic treatment with nebivolol improves endothelium-dependent vasodilation induced by acetylcholine and shear stress and reverses endothelium-dependent vasoconstriction. Furthermore, nebivolol displays distinct hemodynamic properties in patients that include improvements in stroke volume and a decrease in peripheral vascular resistance. These studies demonstrate that nebivolol produces endothelium-dependent vasodilation by increasing NO release, decreasing oxidative stress to increase NO bioavailability, or both. The NO-dependent vasodilatory action of nebivolol, coupled with its high beta(1)-adrenergic receptor selectivity, is unique among the clinically available beta-blockers and contributes to its efficacy and improved tolerability (e.g., less fatigue and sexual dysfunction) as an antihypertensive agent.

Genetics and pathophysiology of arterial stiffness

Arterial stiffness is a cardiovascular risk factor that is independent of arterial pressure. Clinically, carotid-femoral pulse wave velocity (PWV) is the gold-standard parameter of arterial stiffness. Recent genetic studies have revealed specific genes that contribute to arterial stiffening. Here we review the recent findings on genome-wide linkage analyses and candidate gene polymorphism association studies. We also focus on the latest advances in the identification of gene variants affecting PWV using high density array single nucleotide polymorphism technology in a recent genome-wide association (GWA) study. Linkage and polymorphism studies revealed a first group of genes affecting the renin-angiotensin-aldosterone system, elastic fibre structural components, metalloproteinases, and the NO pathway. A second group of genes, identified by polymorphism association studies and possibly involved in the pathophysiology of arterial stiffness, includes beta-adrenergic receptors, endothelin receptors, and inflammatory molecules. The last group of genes, identified by GWA studies and unrelated to currently suspected mechanisms of arterial stiffness, may target transcriptional pathways controlling gene expression, differentiation of vascular smooth muscle cells, apoptosis of endothelial cells, or the immune response within the vascular wall.

Beta-blockers reduce aortic stiffness in hypertension but nebivolol, not atenolol, reduces wave reflection

BACKGROUND

There is conflicting information with regard to the effect of beta-blockers on arterial stiffness and wave reflection. We compared a vasodilating beta-blocker, nebivolol, with atenolol.

METHODS

We randomized 40 subjects with untreated hypertension (mean +/- s.e.m. systolic/diastolic blood pressure (BP) of 160 +/- 3/98 +/- 1 mm Hg, age 49 +/- 1 years) 16 of whom were women, to atenolol 50 mg or nebivolol 5 mg daily for 4 weeks. Arterial stiffness was assessed in terms of carotid-femoral pulse wave velocity (PWV, Complior) and arterial wave reflection (augmentation index (AIx) by applanation tonometry, Sphygmocor).

RESULTS

Both beta-blockers produced an equal reduction in brachial BP but aortic pulse pressure (PP) was reduced to a greater extent by nebivolol (P < 0.05). PWV was decreased significantly by both therapies (nebivolol: from 11.5 +/- 0.5 to 9.9 +/- 0.5 m/s; atenolol: from 11.1 +/- 0.4 to 9.8 +/- 0.4 m/s; P < 0.01) but only nebivolol significantly reduced AIx (from 35 +/- 5 to 28 +/- 2%, P < 0.05). In addition, whereas PP amplification (PP, mm Hg) decreased with atenolol therapy (from 10 +/- 1 to 7 +/- 1, P < 0.01), it increased with nebivolol therapy (from 8 +/- 1 to 14 +/- 3, P < 0.01). Atenolol reduced heart rate to a greater extent than nebivolol did (14 +/- 3/min reduction by atenolol vs. 8 +/- 2/min reduction by nebivolol, P < 0.05). There was no difference between the two treatments in respect of the effect on transit time.

CONCLUSION

The beta-blockers, atenolol and nebivolol, have a similar effect in reducing arterial stiffness in the large elastic aorta, largely secondary to BP reduction. Nebivolol, in contrast to atenolol, has an effect on small muscular arteries, increasing PP amplification and reducing wave reflection, possibly because of increased levels of nitric oxide (NO). Such ancillary properties may impart important distinct hemodynamic effects, and therefore beta-blockers cannot be regarded as a homogeneous group.

Nitric oxide and cardiovascular and renal effects

Nitric oxide (NO) has multiple protective effects for regulating the cardiovascular and renal systems. The major functions include endothelium-dependent relaxation, anti-inflammatory effects, as well as antihypertrophic and antithrombotic activities. Many of the activities mediated by NO are systematically antagonized by angiotensin-II (Ang II), a vasconstrictor peptide. Studies described in the review below have demonstrated that the balance between NO and Ang II activities rather than the absolute concentration of each molecule determines their effects on the physiology and pathophysiology of the cardiovascular and renal systems. NO donors have been used for years as therapeutic agents for a range of cardiovascular conditions including angina, myocardial infarction and for the reduction of arterial stiffness. An understanding of the mechanisms underlying the effects of these medications will enable the development of novel therapies to balance the effects of NO in the cardiovascular system.

Beta-blockers in the management of hypertension: focus on nebivolol

Hypertension is a major cardiovascular risk factor but most patients remain asymptomatic for many years. Successful therapy not only needs to be effective, it also needs to be well tolerated. beta-blockers are well established as effective antihypertensive agents. However, one major drawback to the currently available beta-blockers, particularly the noncardioselective beta-blockers, is their side-effect profile, including sexual dysfunction, fatigue, depression and metabolic abnormalities such as impaired glucose tolerance and lipid abnormalities. Nebivolol (Bystolic), a novel, highly cardioselective, third-generation beta-blocker that recently received approval by the US FDA for the treatment of hypertension in the USA, is effective in treating blood pressure and has a favorable side-effect profile. Studies conducted in Europe, where nebivolol has been available for some time for the treatment of hypertension, have shown that nebivolol achieves blood pressure reductions comparable to other beta-blockers but with fewer side effects. Additionally, nebivolol has demonstrated similar efficacy in blood pressure reduction when compared with calcium channel blockers and inhibitors of the renin-angiotensin system. When combined with hydrochlorothiazide there was an additive antihypertensive effect. Lastly, nebivolol exhibits a vasodilatory property that is related to its effect on nitric oxide, an intrinsic vasodilator produced in the vascular endothelium. Nebivolol enhances nitric oxide bioavailability. Studies have also demonstrated nebivolol's ability to function as an antioxidant and decrease markers of oxidative stress. These effects are believed to ultimately produce a modulation of the endothelial dysfunction typically seen in hypertension.

A comparison of atenolol and nebivolol in isolated systolic hypertension

OBJECTIVES

Some beta-blockers are less effective in reducing central blood pressure than other antihypertensive drugs, which may explain the higher rate of events in subjects randomized to atenolol in recent trials. We hypothesized that nebivolol, a mixed beta-blocker/nitro-vasodilator, would be more effective than atenolol in reducing central blood pressure and augmentation index (AIx). The aim of the present study was to test this in a double-blind, randomized, cross-over study, in a cohort of subjects with isolated systolic hypertension.

METHODS

Following a 2-week placebo run-in, 16 never-treated hypertensive subjects received atenolol (50 mg), nebivolol (5 mg) and placebo, each for 5 weeks, in a random order. Seated brachial blood pressure and heart rate were measured. Aortic blood pressure, AIx and pulse wave velocity (PWV) were assessed non-invasively.

RESULTS

The placebo-corrected fall in brachial pressure was similar between nebivolol and atenolol, as was the reduction in PWV (mean change +/- SEM: -1.0 +/- 0.3 and -1.2 +/- 0.2 m/s; P = 0.2). However, there was less reduction in heart rate (-19 +/- 2 versus -23 +/- 2 beats/min; P < 0.01) and increase in AIx (+6 +/- 1 versus +10 +/- 1%; P = 0.04), following nebivolol. Aortic pulse pressure was significantly lower (50 +/- 2 versus 54 +/- 2 mmHg; P = 0.02) after nebivolol. N-terminal pro-B-type natriuretic peptide (proBNP) rose on both drugs (100 +/- 33 versus 75 +/- 80 pg/ml; P < 0.01 for both, NS for comparison).

CONCLUSIONS

Nebivolol and atenolol have similar effects on brachial blood pressure and aortic stiffness. However, nebivolol reduces aortic pulse pressure more than atenolol, which may be related to a less pronounced rise in AIx and bradycardia. Whether this will translate into differences in clinical outcome requires further investigation.

The vasodilatory beta-blockers

Although well established in treating hypertension and cardiovascular (CV) disease, clinical trial data suggest that beta-blockers (eg, atenolol) may be less effective than other antihypertensive classes in reducing stroke and CV mortality despite similar blood pressure (BP) reductions. One possible explanation is that atenolol is less effective in reducing central aortic pressure. Newer vasodilating beta-blockers may prove more effective in reducing central pressure and cardiovascular events. Carvedilol and labetalol appear to cause vasodilation through alpha(1)-receptor blockade; nebivolol induces endothelium-dependent vasodilation by stimulating nitric oxide bioactivity. Their favorable hemodynamic profile includes reduction of peripheral vascular resistance (PVR) while maintaining or improving cardiac output (CO), stroke volume, and left ventricular function, whereas nonvasodilating beta-blockers tend to raise PVR and reduce CO and left ventricular function. Compared with conventional beta-blockers, vasodilating beta-blockers have beneficial hemodynamic effects including decreased pressure wave reflection from the periphery, leading to decreases in central aortic blood pressure. Larger trials are needed to determine whether reduced central pressure will translate into improved CV outcomes compared with nonvasodilating beta-blockers.