The role of nitric oxide in improving endothelial function and cardiovascular health: focus on nebivolol

Chronic Nebivolol Treatment Suppresses Endothelin-1-Mediated Vasoconstrictor Tone in Adults With Elevated Blood Pressure

Endothelin-1 (ET-1) plays a major role in the pathophysiology of hypertension and its associated cardiovascular risk. We tested the hypothesis that chronic nebivolol treatment reduces ET-1-mediated vasoconstrictor tone in adult humans with elevated blood pressure (BP). Furthermore, reducing ET-1 vasoconstrictor activity contributes to the improvement in endothelial vasodilator function associated with nebivolol treatment. Forty-two middle-aged adults with elevated BP (systolic BP ≥130 mm Hg or diastolic BP ≥85 mm Hg) completed a 3-month, double-blind, randomized, placebo controlled trial: 14 received nebivolol (8 men/6 women; 5 mg per day); 14 received metoprolol succinate (9 men/5 women; 100 mg per day); and 14 received placebo (9 men/5 women). Forearm blood flow (plethysmography) responses to selective (BQ-123: 100 nmol/min; 60 minutes) and nonselective (BQ-123+BQ-788 [50 nmol/min]; 60 minutes) ET-1 receptor blockade, as well as acetylcholine (4.0, 8.0, and 16.0 μg per 100 mL of tissue per minute) in the absence and presence of nonselective ET-1 receptor blockade were determined before and after each treatment intervention. Forearm blood flow responses to BQ-123 and BQ-123+BQ-788 were similarly and significantly elevated (≈30% and 60%, respectively) from baseline in all 3 groups. Nebivolol, but not metoprolol or placebo, therapy resulted in a marked (≈25% and 45%; P<0.05) reduction in forearm blood flow response to BQ-123 and BQ-123+BQ-788. Moreover, after nebivolol therapy only, vasodilator response to acetylcholine was not significantly increased by ET-1 receptor blockade. These results demonstrate that nebivolol, but not metoprolol, treatment reduces ET-1-mediated vasoconstrictor tone in adult humans with elevated BP. In addition, nebivolol-induced reduction in ET-1-mediated vasoconstrictor tone underlies the favorable effects of this β-blocker on endothelial vasodilation.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01395329.

Hypertension treatment in the Asia-Pacific: the role of and treatment strategies with nebivolol

Hypertension is a common disease, and hypertensive patients are at increased risk of cardiovascular events. The prevalence and socioeconomic burden of hypertension in the Asia-Pacific region are predicted to increase in the coming decades. Effective blood pressure lowering reduces overall cardiovascular morbidity and mortality in patients, yet doubt has been raised regarding the use of (mainly older generation) β-blockers as initial therapy in hypertension. Consequently, several international treatment guidelines do not recommend β-blockers for the treatment of hypertension. However, in contrast to first-generation and second-generation β-blockers, the third-generation, vasodilating β-blocker nebivolol has a considerably better metabolic, haemodynamic and side effect profile. In addition to providing effective blood pressure control similar to other β-blockers and drugs from other antihypertensive classes, nebivolol exerts a dual mechanism for increasing the bioavailability of the naturally occurring vasodilator nitric oxide. The clinical benefits and significance of enhancing nitric oxide levels in hypertensive patients have been shown in direct comparisons of nebivolol with other β-blockers. While β-blockers generally provide comparable blood pressure reductions, only nebivolol demonstrated enhanced vasodilation and blood flow by increasing the expression of endothelial nitric oxide synthase and therefore increasing nitric oxide release from the endothelium. In contrast to other β-blockers, therefore, it has been suggested that nebivolol has beneficial effects in several hypertensive subgroups due to its vasodilating properties. Considering the existing data, it may be timely for treatment guidelines to recommend third-generation vasodilating β-blockers as a first-line option for the pharmacotherapy of hypertension.

Comparative effects of nebivolol and metoprolol on red cell distribution width and neutrophil/lymphocyte ratio in patients with newly diagnosed essential hypertension

High level of circulating red cell distribution width (RDW) and neutrophil/lymphocyte (N/L) ratio may reflect ongoing vascular inflammation and play an important role in pathophysiology of hypertension. We evaluate the effects of nebivolol and metoprolol on the RDW and N/L in new essential hypertensive patients. After baseline assessment, 72 patients were randomly allocated to 5 mg/d of nebivolol (n = 37, 20 men) or 100 mg/d of metoprolol (n = 35, 18 men) and treated for 6 months. Blood pressure (BP), heart rate (HR), RDW, and N/L were measured before and after treatment. BP significantly decreased with both drugs (P < 0.001). Analog reduction was observed for resting HRs (P < 0.001), but metoprolol caused greater HR fall as compared with nebivolol (P < 0.001). After 6 months of treatment, nebivolol significantly lowered not only RDW but also the total white blood cell and N/L (P < 0.001, P = 0.023, P = 0.017, respectively). No changes were observed in metoprolol group. Percent decrease in RDW was found to be significantly higher in nebivolol than in the metoprolol group (P = 0.001) and remained also after correction for confounders (P = 0.012). Nebivolol improved RDW and N/L to a greater extent than metoprolol in patients with hypertension. These favorable effects may participate, together with the BP reduction, at the favorable properties of the drug in hypertension.

Stimulation of platelet nitric oxide production by nebivolol prevents thrombosis

OBJECTIVE

dl-Nebivolol, a selective β1-adrenergic receptor antagonist, besides its hypotensive activity exerts vasodilatory and platelet inhibitory effects in vitro by a mechanism involving nitric oxide (NO). Our aim was to evaluate whether nebivolol exerts in vivo antithrombotic effects, to unravel the mechanism of this action and to clarify the relative roles of its 2 enantiomers: d- and l-nebivolol.

METHODS AND RESULTS

In wild-type mice, dl-nebivolol, l-nebivolol, and d-nebivolol, but not bisoprolol, reduced mortality consequent to platelet pulmonary thromboembolism induced by the intravenous injection of collagen plus epinephrine (-44%, -45%, -29%, respectively; P<0.05), whereas in eNOS(-/-) mice only dl-nebivolol and d-nebivolol were effective. dl-Nebivolol, l- and d-nebivolol reduced photochemical damage-induced femoral artery thrombosis in wild-type mice, whereas in eNOS(-/-) mice only dl-nebivolol and d-nebivolol were active. Moreover, dl-nebivolol and l-nebivolol increased plasma, urinary-, and platelet-derived nitrites and nitrates (NOx), NO degradation products, in wild-type but not in eNOS(-/-) mice. In vivo platelet activation, assessed by platelet P-selectin expression, was reduced by dl-nebivolol and l- and d-nebivolol in wild-type mice but only by dl-nebivolol and d-nebivolol in eNOS(-/-) mice. In bone marrow-transplanted, chimeric mice with only blood cells, and not the endothelium, producing NO dl-nebivolol and l-nebivolol maintained their antithrombotic activity, whereas they lose it in chimeras with only endothelium, and not blood cells, producing NO. In vitro, with isolated platelets, dl-nebivolol and l-nebivolol, but not d-nebivolol and bisoprolol, increased platelet cGMP and NOx formation. Treatment with dl-nebivolol and l-nebivolol increased phophorylated eNOS in platelets.

CONCLUSIONS

Our data show that dl-nebivolol exerts an antithrombotic activity by stimulating the formation of NO by platelets, and that this effect is generated by its l-enantiomer, whereas the d-enantiomer exerts a weak antiplatelet effect because of β-adrenergic receptor-independent stimulation of adenyly cyclase. These results confirm that platelet-derived NO plays a role in thrombosis prevention and it may represent a target of pharmacological intervention.

Beneficial effects of nebivolol and hydrochlorothiazide combination in spontaneously hypertensive rats

Objective

This study examined the combined effect of nebivolol (NEB) and hydrochlorothiazide (HCTZ) on cardiovascular function in spontaneously hypertensive rats (SHR).

Methods

SHR normotensive male rats were randomly assigned to five groups ( n = 8 per group): (i) SHR control group; (ii) NEB 2 mg/kg per day group; (iii) HCTZ 10 mg/kg per day group; (iv) NEB 2 mg/kg per day + HCTZ 10 mg/kg per day group; (v) Eight age-matched Wistar-Kyoto normotensive male rats served as the control group. All groups were treated orally for 8 weeks.

Results

The combination of NEB + HCTZ synergistically reduced systolic blood pressure and heart rate compared with either monotherapy. HCTZ increased water intake, which is a sign of diuresis. NEB reduced plasma angiotensin II concentration, which was increased in SHR and after HCTZ treatment. NEB + HCTZ increased plasma nitric oxide (NO) concentration and NO synthase activity, which were both reduced in SHR. NEB + HCTZ normalized femoral arterial vasorelaxation induced by acetylcholine, which was impaired in SHR.

Conclusions

The combination of NEB + HCTZ provided a number of beneficial and additive effects due to the synergistic characteristics of both drugs, in an experimental rat model of hypertension.

Vasodilating versus first-generation β-blockers for cardiovascular protection

The utility of β-blockers in the treatment of hypertension has created much speculation as to their efficacy in patients with comorbid conditions, and there are concerns regarding their adverse metabolic effects. It is important to note that these findings were observed with traditional β-blockers, such as atenolol and metoprolol. The newer generation of β-blockers, namely carvedilol and nebivolol, is changing the manner in which β-blockers are viewed in hypertension management. Their ability to inhibit A1 adrenoreceptors and influence nitric oxide leads to vasodilation, which traditional β-blockers fail to do. These agents have been shown to have favorable metabolic effects while maintaining the beneficial cardiovascular effects of this drug class in post-myocardial infarction patients and the heart failure population.

Choosing an antihypertensive combination with a more efficient central blood pressure reduction

Not all blood pressure (BP)-lowering agents have the same effect on central BP, but we know that central BP, in itself, is a risk factor for cardiovascular diseases. Therefore, antihypertensive agents should ideally also have a central BP-lowering effect. In this paper the authors evaluate the effect of adding a calcium channel blocker to a β-blocker. The results show this combination does not reverse the lesser effect of β-blockers on central BP, and that the combination of valsartan plus amlodipine is more effective in lowering central BP than a combination of amlodipine plus atenolol.