Nitric Oxide Contributes to Vasomotor Tone in Hypertensive African Americans Treated With Nebivolol and Metoprolol

Inhibition of superoxide and iNOS augment cutaneous nitric oxide-dependent vasodilation in non-Hispanic black young adults

We assessed the combined effect of superoxide and iNOS inhibition on microvascular function in non-Hispanic Black and non-Hispanic White participants (n = 15 per group). Participants were instrumented with four microdialysis fibers: (1) lactated Ringer's (control), (2) 10 μM tempol (superoxide inhibition), (3) 0.1 mM 1400 W (iNOS inhibition), (4) tempol + 1400 W. Cutaneous vasodilation was induced via local heating and NO-dependent vasodilation was quantified. At control sites, NO-dependent vasodilation was lower in non-Hispanic Black (45 ± 9% NO) relative to non-Hispanic White (79 ± 9% NO; p < 0.01; effect size, d = 3.78) participants. Tempol (62 ± 16% NO), 1400 W (78 ± 12% NO) and tempol +1400 W (80 ± 13% NO) increased NO-dependent vasodilation in non-Hispanic Black participants relative to control sites (all p < 0.01; d = 1.22, 3.05, 3.03, respectively). The effect of 1400 W (p = 0.04, d = 1.11) and tempol +1400 W (p = 0.03, d = 1.22) was greater than tempol in non-Hispanic Black participants. There was no difference between non-Hispanic Black and non-Hispanic White participants at 1400 W or tempol + 1400 W sites. These data suggest iNOS has a greater effect on NO-dependent vasodilation than superoxide in non-Hispanic Black participants.

Strategies of Pathogens to Escape from NO-Based Host Defense

Nitric oxide (NO) is an essential signaling molecule present in most living organisms including bacteria, fungi, plants, and animals. NO participates in a wide range of biological processes including vasomotor tone, neurotransmission, and immune response. However, NO is highly reactive and can give rise to reactive nitrogen and oxygen species that, in turn, can modify a broad range of biomolecules. Much evidence supports the critical role of NO in the virulence and replication of viruses, bacteria, protozoan, metazoan, and fungi, thus representing a general mechanism of host defense. However, pathogens have developed different mechanisms to elude the host NO and to protect themselves against oxidative and nitrosative stress. Here, the strategies evolved by viruses, bacteria, protozoan, metazoan, and fungi to escape from the NO-based host defense are overviewed.

Race and sex differences in cardiovascular autonomic regulation

Racial and ethnic differences in cardiovascular morbidity and mortality persist despite advances in risk factor identification and implementation of evidence-based treatment strategies. African American men and women are disproportionately affected by cardiovascular risk factors, particularly hypertension. In this context, previous studies have identified sex and racial differences in autonomic cardiovascular regulation which may contribute to the development of hypertension and its high morbidity burden among African Americans. In this review, we provide a comprehensive evaluation of the potential pathophysiological mechanisms of blood pressure control and their differences based on sex and race. These mechanisms include obesity-induced sympathetic activation, sympatho-vascular transduction, baroreflex sensitivity and adrenoreceptor vascular sensitivity, which have been the subjects of prior investigation in this field. Understanding the racial differences in the pathophysiology of hypertension and its co-morbid conditions would allow us to implement better treatment strategies tailored to African Americans, with the ultimate goal of reducing cardiovascular mortality in this population.

Sensory nerve-mediated and nitric oxide-dependent cutaneous vasodilation in normotensive and prehypertensive non-Hispanic blacks and whites

The purpose of this study was to investigate the effect of race and subclinical elevations in blood pressure (i.e., prehypertension) on cutaneous sensory nerve-mediated and nitric oxide (NO)-dependent vasodilation. We recruited participants who self-identified as either non-Hispanic black (n = 16) or non-Hispanic white (n = 16). Within each group, participants were subdivided as either normotensive (n = 8 per group) or prehypertensive (n = 8 per group). Each participant was instrumented with four intradermal microdialysis fibers: 1) control (lactated Ringer's), 2) 5% lidocaine (sensory nerve inhibition), 3) 20 mM N^ω-nitro-l-arginine methyl ester (l-NAME) (NO synthase inhibition), and 4) lidocaine + l-NAME. Skin blood flow was assessed via laser-Doppler flowmetry, and each site underwent local heating from 33°C to 39°C. At the plateau, 20 mM l-NAME were infused at control and lidocaine sites to quantify NO-dependent vasodilation. Maximal vasodilation was induced via 54 mM sodium nitroprusside and local heating to 43°C. Data are means ± SD. Sensory nerve-mediated cutaneous vasodilation was reduced in prehypertensive non-Hispanic white (34 ± 7%) and both non-Hispanic black groups (normotensive, 20 ± 9%, prehypertensive, 24 ± 15%) relative to normotensive non-Hispanic whites (54 ± 12%). NO-dependent vasodilation was also reduced in prehypertensive non-Hispanic white (41 ± 7%) and both non-Hispanic black groups (normotensive, 44 ± 7%, prehypertensive, 19 ± 7%) relative to normotensive non-Hispanic whites (60 ± 11%). The decrease in NO-dependent vasodilation in prehypertensive non-Hispanic blacks was further reduced relative to all other groups. These data suggest subclinical increases in blood pressure adversely affect sensory-mediated and NO-dependent vasodilation in both non-Hispanic blacks and whites.NEW & NOTEWORTHY Overt hypertension is known to reduce cutaneous sensory nerve-mediated and nitric oxide (NO)-dependent vasodilation, but the effect of subclinical increases in blood pressure (i.e., prehypertension) is unknown. The combined effect of race and prehypertension is also unknown. In this study, we found that prehypertension reduces cutaneous sensory nerve-mediated and NO-dependent vasodilation in both non-Hispanic white and black populations, with the greatest reductions observed in prehypertensive non-Hispanic blacks.

Effects of nebivolol versus other antihypertensive drugs on the endothelial dysfunction in patients with essential hypertension

We aim to determine whether nebivolol has a better effect on endothelial dysfunction compared with other β-blockers or other classes of antihypertensive drugs. Searches of the PubMed, Embase etc. were performed to analyze all the randomized controlled trials using nebivolol to treat essential hypertension. The primary end points included a measurement of peripheral endothelial function by brachial flow mediated vasodilatation (FMD) or forearm blood flow (FBF). A random-effect model was used to perform the meta-analysis when the studies showed significant heterogeneity, otherwise a descriptive analysis was conducted. Ten studies (689 patients) were included in qualitative analysis, four of which were included in quantitative synthesis. Meta-analysis showed that the changed FMD value before and after treatment with nebivolol was not statistically different from those treated with other β-blockers [mean difference = 1.12, 95% confidence interval (CI): −0.56, 2.81, P=0.19]. Descriptive analysis indicated that nebivolol did not have a better endothelium-protective effect than other classes of antihypertensive drugs including olmesartan and perindopril. Nebivolol is not a unique endothelial function-protective agent distinguished from other β-blockers or other classes of antihypertensive drugs. Reversal of endothelial dysfunction is a key point in the prevention and therapy of essential hypertension.

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.

Rethinking Endothelial Dysfunction as a Crucial Target in Fighting Heart Failure

Endothelial dysfunction is characterized by nitric oxide dysregulation and an altered redox state. Oxidative stress and inflammatory markers prevail, thus promoting atherogenesis and hypertension, important risk factors for the development and progression of heart failure. There has been a reemerging interest in the role that endothelial dysfunction plays in the failing circulation. Accordingly, patients with heart failure are being clinically assessed for endothelial dysfunction via various methods, including flow-mediated vasodilation, peripheral arterial tonometry, quantification of circulating endothelial progenitor cells, and early and late endothelial progenitor cell outgrowth measurements. Although the mechanisms underlying endothelial dysfunction are intimately related to cardiovascular disease and heart failure, it remains unclear whether targeting endothelial dysfunction is a feasible strategy for ameliorating heart failure progression. This review focuses on the pathophysiology of endothelial dysfunction, the mechanisms linking endothelial dysfunction and heart failure, and the various diagnostic methods currently used to measure endothelial function, ultimately highlighting the therapeutic implications of targeting endothelial dysfunction for the treatment of heart failure.

Effect of nebivolol or atenolol vs. placebo on cardiovascular health in subjects with borderline blood pressure: the EVIDENCE study

Pharmacotherapy to protect the arteries may be appropriate for individuals with high-normal blood pressure who are at risk for future cardiovascular disease (CVD). Nebivolol (NEB) in contrast to atenolol (ATE) may have a beneficial effect on endothelial function and may be more effective than ATE in preventing CVD. Sixty subjects with preHTN or borderline BP and abnormal small artery elasticity (SAE) underwent evaluation with 10 tests, including large and small artery elasticity, resting and treadmill exercise BP, carotid intimal-media thickness, retinal vascular photography, micro-albuminuria, electrocardiography, echocardiography, and plasma B-type natriuretic peptide level. Each test scored as normal (0), borderline (1), or abnormal (2), and the total disease score (DS) was calculated by adding the test scores. Subjects were randomized double-blind to placebo (PLAC, n = 22), NEB 5/10 mg/day (n = 20), or ATE 25/50 mg/day (n = 18) once daily for 9 months. After 9 months, in the group receiving NEB the mean (standard deviation) DS decreased from baseline 4.3 (2.6) to 2.8 (2.4) (P < 0.007), with ATE from 5.4 (2.5) to 3.5 (1.9) (P = 0.0006), and with PLAC from 5.2 (3.0) to 4.5 (2.6) (P = 0.18). SAE increased in the NEB group from 6.0 (2.2) to 8.4 (3.4) ml/mmHg × 100 (P = 0.0001), whereas there was no significant change in the ATE and PLAC groups. Thus, nebivolol improves small artery function more than atenolol in asymptomatic subjects with preHTN or borderline BP, despite their similar BP-lowering effect.