Impaired endothelial function in arterial hypertension and hypercholesterolemia: potential mechanisms and differences

Evidence of a causal relationship between blood pressure and pathological scars: a bidirectional Mendelian randomization study

Background

Recent advancements in basic medicine and epidemiology suggest a potential influence of blood pressure on scar formation, yet the specifics of this relationship are not fully understood. This study aims to clarify the causal link between blood pressure and the development of pathological scars using Mendelian randomization (MR).

Methods

This study employed genetic variants closely linked to blood pressure as instrumental variables to explore the relationship between blood pressure and pathological scars. The inverse variance weighted (IVW) method was used for analysis.

Results

Our analysis identified a notable association where higher blood pressure was correlated with a lower risk of pathological scars. Specifically, an increase in diastolic blood pressure (odds ratio [OR] per standard deviation increase: 0.67 [95% Confidence Interval [CI], 0.49-0.99]), systolic blood pressure (OR per standard deviation increase: 0.66 [95% CI, 0.46-0.93]), and hypertension (pooled OR: 0.39 [95% CI, 0.18-0.85]) were significantly associated with a reduced risk of keloids. Similarly, a genetic predisposition to hypertension (pooled OR: 0.31 [95% CI, 0.11-0.89]) was significantly associated with a reduced risk of hypertrophic scars. Neither reverse MR analysis nor Steiger's test indicated a significant reverse causal relationship between hypertension and either keloids or hypertrophic scars.

Conclusion

The findings suggest a protective role of higher blood pressure against the development of pathological scars, including keloids and hypertrophic scars. However, the inconsistency observed across different MR methods warrants cautious interpretation and underscores the need for further investigation to confirm these findings.

Effect of soluble fiber on blood pressure in adults: a systematic review and dose-response meta-analysis of randomized controlled trials

OBJECTIVES

Pervious epidemiologic evidence indicates that soluble fiber is protective against hypertention: however, randomized controlled trials (RCTs) have presented varying results. In the present study, we aimed to conduct a systematic review and dose-response meta-analysis to summarize published RCTs which assess the effect of soluble fiber supplementation on systolic blood pressure (SBP) and diastolic blood pressure (DBP).

METHODS

Scopus, PubMed, and ISI Web of Sciences were searched to identify relevant studies up to Aug 2022. We estimated the change in blood pressure for each 5 g/d increment in soluble fiber supplementation in each trial and then calculated the weighted mean difference (WMD) and 95%CI using a random-effects model. We estimated dose-dependent effects using a dose-response meta-analysis of differences in means. The risk of bias for study was assessed using the Cochrane tool. Publication bias was evaluated via funnel plot and Begg's test and Egger's test.

RESULTS

Eighty-three eligible studies with total sample size of 5,985 participants were included in the meta-analysis. Soluble fiber supplementation significantly decreased SBP (WMD: -1.36 mmHg, 95% CI: -2.13 to -0.60, P < 0.001; I2 = 47.1%, P < 0.001) and DBP (WMD: -0.72 mmHg, 95% CI: -1.26 to -0.18, P = 0.009; I2 = 45.4%, P < 0.001). Each 5 g/d increment in soluble fiber supplementation had a significant reduction in SBP (WMD: -0.54 mmHg; 95%CI: -0.86, -0.22, P = 0.001; I2 = 52.2, Phet < 0.001) and DBP (WMD: -0.28 mmHg; 95%CI: -0.49, -0.80, P = 0.007; I2 = 43.1%, Phet < 0.001). The levels of SBP decreased proportionally with the increase in soluble fiber supplementation up to 20 g/d (MD20g/d: -1.79 mmHg, 95%CI: -2.86, -0.71).

CONCLUSION

Current evidence indicated the beneficial effect of soluble fiber supplementation on blood pressure. Our findings suggest that soluble fiber supplementation could contribute to the management of hypertension and the reduction of cardiovascular disease risk.

Nutritional Evaluation of Sea Buckthorn “Hippophae rhamnoides” Berries and the Pharmaceutical Potential of the Fermented Juice

Sea buckthorn is a temperate bush plant native to Asian and European countries, explored across the world in traditional medicine to treat various diseases due to the presence of an exceptionally high content of phenolics, flavonoids and antioxidants. In addition to the evaluation of nutrients and active compounds, the focus of the present work was to assess the optimal levels for L. plantarum RM1 growth by applying response surface methodology (RSM), and to determine the impact of juice fermentation on antioxidant, anti-hypertension and anticancer activity, as well as on organoleptic properties. Sea buckthorn berries were shown to contain good fiber content (6.55%, 25 DV%), high quality of protein (3.12%, 6.24 DV%) containing: histidine, valine, threonine, leucine and lysine (with AAS 24.32, 23.66, 23.09, 23.05 and 21.71%, respectively), and 4.45% sugar that provides only 79 calories. Potassium was shown to be the abundant mineral content (793.43%, 22.66 DV), followed by copper and phosphorus (21.81 and 11.07 DV%, respectively). Sea buckthorn juice exhibited a rich phenolic, flavonoid and carotenoid content (283.58, 118.42 and 6.5 mg/g, respectively), in addition to a high content of vitamin C (322.33 mg/g). The HPLC profile indicated that benzoic acid is the dominant phenolic compound in sea buckthorn berries (3825.90 mg/kg). Antioxidant potentials (DPPH and ABTS) of sea buckthorn showed higher inhibition than ascorbic acid. Antimicrobial potentials were most pronounced against Escherichia coli BA12296 (17.46 mm). The probiotic growth was 8.5 log cfu/mL, with juice concentration, inoculum size and temperature as the main contributors to probiotic growth with a 95% confidence level. Fermentation of sea buckthorn juice with L. plantarum RM1 enhanced the functional phenolic and flavonoid content, as well as antioxidant and antimicrobial activities. The fermentation with L. plantarum RM1 enhanced the anti-hypertension and anticancer properties of the sea buckthorn juice and gained consumers’ sensorial overall acceptance.

Exploring the role of body mass index in relationship of serum nitric oxide and advanced glycation end products in apparently healthy subjects

This study aimed to identify any association of serum nitric oxide (NO) and advanced glycation end products (AGEs) with body mass index (BMI) in apparently healthy subjects. In this cross-sectional study, participants were 90 apparently healthy subjects, categorized into three BMI groups as follows: BMI≤19.5 (n = 21), 19.6≤BMI≤24.9 (n = 35), and BMI≥25 (n = 34). Serum levels of NO were measured by griess reaction method. Determination of serum pentosidine and carboxymethyllysine (CML) was done using ELISA. Median (95% confidence interval [CI]: lower- upper) of serum NO in subjects with BMI≥25 were 68.94 (CI: 55.01–70.56) μmol/L, which was higher compared with 19.6≤BMI≤24.9 and BMI≤19.5 groups (22.65 (CI: 19.29–28.17) μmol/L and 8.00 (CI: 9.12–29.58) μmol/L, respectively). Serum NO positively correlated with BMI in total subjects (r = 0.585, p<0.001), which this correlation was significant in both male and female groups (r = 0.735, p<0.001 and r = 0.476, p = 0.001, respectively). Serum pentosidine and CML were significantly lower in subjects with higher BMI. Further, BMI showed negative correlations with pentosidine and CML (r = -0.363, p<0.001 and r = -0.484, p<0.001, respectively). There were not any significant differences in serum NO, pentosidine, and CML levels between sex groups. After adjusting the effects of confounders (BMI, sex, age, and waist to hip ratio), serum NO significantly correlated with serum pentosidine and CML (r = -0.319, p = 0.003 and r = -0.433, p<0.001, respectively). It is concluded that higher BMI is accompanied by increased serum NO and suppressed pentosidine and CML.

Emerging role of SIRT3 in mitochondrial dysfunction and cardiovascular diseases

As a nicotinamide adenine dinucleotide (NAD)⁺-dependent protein deacetylase, SIRT3 is highly expressed in tissues with high metabolic turnover and mitochondrial content. It has been demonstrated that SIRT3 plays a critical role in maintaining normal mitochondrial biological function through reversible protein lysine deacetylation. SIRT3 has a variety of substrates that are involved in mitochondrial biological processes such as energy metabolism, reactive oxygen species production and clearance, electron transport chain flux, mitochondrial membrane potential maintenance, and mitochondrial dynamics. In the suppression of SIRT3, functional deficiencies of mitochondria contribute to the development of various cardiovascular disorders. Activation of SIRT3 may represent a promising therapeutic strategy for the improvement of mitochondrial function and the treatment of relevant cardiovascular disorders. In the current review, we discuss the emerging roles of SIRT3 in mitochondrial derangements and subsequent cardiovascular malfunctions, including cardiac hypertrophy and heart failure, ischemia-reperfusion injury, and endothelial dysfunction in hypertension and atherosclerosis.

Beneficial effects of cherry consumption as a dietary intervention for metabolic, hepatic and vascular complications in type 2 diabetic rats

Background

Oxidative stress (OS) plays an important role in type 2 diabetes (T2D) pathogenesis and its complications. New therapies target natural antioxidants as an alternative and/or supplemental strategy to prevent and control them. Our previous chemical and biological studies highlighted the important antioxidant activities of cherries, among other fruits and vegetables, thus we aimed to determine in vivo effects of 2-month long cherry consumption using a high-fat/high-fructose (HFHF) model of diabetic-rats (Lozano et al. in Nutr Metab 13:15, 2016).

Methods

After 2 months of HFHF, male Wistar rats were divided into: HFHF and HFHF enriched in cherry (nutritional approach) or standard diet ND (lifestyle measures) and ND plus cherry during 2 months. Metabolic, lipidic, oxidative parameters were quantified. Tissues (liver, pancreas and vessels) OS were assessed and hepatic (steatosis, fibrosis, inflammation) and vascular (endothelial dysfunction) complications were characterized.

Results

T2D was induced after 2 months of HFHF diet, characterized by systemic hyperglycaemia, hyperinsulinemia, glucose intolerance, dyslipidaemia, hyperleptinemia, and oxidative stress associated with endothelial dysfunction and hepatic complications. Cherry consumption for 2 months, in addition to lifestyle measures, in T2D-rats decreased and normalized the systemic disturbances, including oxidative stress complications. Moreover, in the vessel, cherry consumption decreased oxidative stress and increased endothelial nitric oxide (NO) synthase levels, thus increasing NO bioavailability, ensuring vascular homeostasis. In the liver, cherry consumption decreased oxidative stress by inhibiting NADPH oxidase subunit p22phox expression, nuclear factor erythroid-2 related factor 2 (Nrf2) degradation and the formation of reactive oxygen species. It inhibited the activation of sterol regulatory element-binding proteins (1c and 2) and carbohydrate-responsive element-binding protein, and thus decreased steatosis as observed in T2D rats. This led to the improvement of metabolic profiles, together with endothelial and hepatic function improvements.

Conclusion

Cherry consumption normalized vascular function and controlled hepatic complications, thus reduced the risk of diabetic metabolic disorders. These results demonstrate that a nutritional intervention with a focus on OS could prevent and/or delay the onset of vascular and hepatic complications related to T2D.

Electronic supplementary material

The online version of this article (10.1186/s12933-018-0744-6) contains supplementary material, which is available to authorized users.

LOX-1 receptor: A potential link in atherosclerosis and cancer

Altered production of reactive oxygen species (ROS), causing lipid peroxidation and DNA damage, contributes to the progression of atherosclerosis and cancer. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a lectin-like receptor for oxidized low-density lipoproteins (ox-LDL) primarily expressed in endothelial cells and vasculature-rich organs. LOX-1 receptors is a marker for atherosclerosis, and once activated by ox-LDL or other ligands, stimulates the expression of adhesion molecules, pro-inflammatory signaling pathways and proangiogenic proteins, including NF-kB and VEGF, in vascular endothelial cells and macrophages. Several different types of cancer reported LOX-1 gene upregulation, and numerous interplays exist concerning LOX-1 in atherosclerosis, metabolic diseases and cancer. One of them involves NF-kB, an oncogenic protein that regulates the transcription of several inflammatory genes response. In a model of cellular transformation, the MCF10A ER-Src, inhibition of LOX-1 gene reduces NF-kB activation and the inflammatory and hypoxia pathways, suggesting a mechanistic connection between cellular transformation and atherosclerosis. The remodeling proteins MMP-2 and MMP-9 have been found increased in angiogenesis in atherosclerotic plaque and also in human prostate cancer cells. In this review, we outlined the role of LOX-1 in atherogenesis and tumorigenesis as a potential link in these diseases, suggesting that LOX-1 inhibition could represent a promising strategy in the treatment of atherosclerosis and tumors.

A polymorphism in a major antioxidant gene (Kelch-like ECH-associated protein 1) predicts incident cardiovascular events in chronic kidney disease patients: an exploratory study

OBJECTIVE

Oxidative stress is considered a major pathway conducive to cardiovascular disease in chronic kidney disease (CKD) patients. However, observational studies and clinical trials testing this relationship are controversial. The Nuclear factor-erythroid-2-related factor 2 (Nrf2)-Kelch-like ECH-associated protein 1 (Keap1) system is a major system regulating antioxidant mechanisms in living organisms. Owing to the fact that genes are transmitted randomly (Mendelian randomization), genetic variants may provide unconfounded assessment of putative causal risk factors.

METHODS

We have therefore explored the association of eight polymorphisms in the Nrf2 gene and three polymorphisms in the Keap1 gene (capturing over 80% of the genetic variance in the same genes) with cardiovascular events in a multicenter cohort study of 758 CKD patients.

RESULTS

During the follow-up period, 117 patients had fatal and nonfatal cardiovascular events and 42 died. The hazard rate of fatal and nonfatal cardiovascular outcomes was about twice higher in patients with the AA or the CA genotype (dominant model) in the rs110857735 polymorphism of the Keap1 gene (hazard rate: 1.85, 95% CI: 1.20-2.84, P = 0.005) than in those with the CC genotype. Further analyses adjusting for Framingham risk factors and CKD-specific risk factors and a bootstrapping validation analysis did not modify the strength of this association. No association was registered between other Keap1 and Nrf2 polymorphisms and cardiovascular disease in the same cohort.

CONCLUSION

In this exploratory study a gene-variant in Keap1, a major gene regulating the antioxidant response, predicts incident cardiovascular events in CKD patients. This finding is in keeping with the hypothesis implicating oxidative stress in cardiovascular disease in this population.

The Protective Effect of Antioxidants Consumption on Diabetes and Vascular Complications

Obesity and diabetes is generally accompanied by a chronic state of oxidative stress, disequilibrium in the redox balance, implicated in the development and progression of complications such as micro- and macro-angiopathies. Disorders in the inner layer of blood vessels, the endothelium, play an early and critical role in the development of these complications. Blunted endothelium-dependent relaxation and/or contractions are quietly associated to oxidative stress. Thus, preserving endothelial function and oxidative stress seems to be an optimization strategy in the prevention of vascular complications associated with diabetes. Diet is a major lifestyle factor that can greatly influence the incidence and the progression of type 2 diabetes and cardiovascular complications. The notion that foods not only provide basic nutrition but can also prevent diseases and ensure good health and longevity is now attained greater prominence. Some dietary and lifestyle modifications associated to antioxidative supply could be an effective prophylactic means to fight against oxidative stress in diabesity and complications. A significant benefit of phytochemicals (polyphenols in wine, grape, teas), vitamins (ascorbate, tocopherol), minerals (selenium, magnesium), and fruits and vegetables in foods is thought to be capable of scavenging free radicals, lowering the incidence of chronic diseases. In this review, we discuss the role of oxidative stress in diabetes and complications, highlight the endothelial dysfunction, and examine the impact of antioxidant foods, plants, fruits, and vegetables, currently used medication with antioxidant properties, in relation to the development and progression of diabetes and cardiovascular complications.

Role of SIRT3 in Angiotensin II-induced human umbilical vein endothelial cells dysfunction

BACKGROUND

SIRT3, a member of the sirtuin family of NAD(+)-dependent deacetylases, resides primarily in the mitochondria and has been shown to deacetylate several metabolic and respiratory enzymes that regulate important mitochondrial functions. Previous researches show an important role of SIRT3 in regulating the production of reactive oxygen species (ROS), and highlight the ability of SIRT3 to protect cells from oxidative damage. A key substance of renin-angiotensin-aldosterone system (RAAS), Angiotensin II (AngII) can induce cells dysfunction by increasing the production of ROS. In this paper, we focus on the role of SIRT3 in AngII-induced human umbilical vein endothelial cells (HUVECs) dysfunction.

METHODS

To study the influence of AngII on SIRT3 expression, HUVECs were treated with AngII of 10(-7), 10(-6), 10(-5) mol/L for 24 h. SIRT3 expression was detected by wester-blotting analysis and RT-PCR. In addition, to research the role of SIRT3 in AngII-induced HUVECs,we used SIRT3 siRNA to knock down SIRT3 expression in HUVECs. Cells pretreated with negative control siRNA or SIRT3 siRNA were exposed to AngII for 24 h, and endothelial nitric oxide synthase (eNOS) expression, eNOS activity, total level of nitric oxide (NO) and ROS generation of each group were detected.

RESULTS

Here we show that AngII treatment could increase generation of ROS, and decrease eNOS activity and total level of NO, while upregulated eNOS expression as a compensatory mechanism. The stimulation of AngII upregulated the expression of SIRT3 in HUVECs. SIRT3 siRNA worsen the AngII-induced effects above, besides, downregulated eNOS protein expression.

CONCLUSION

These data suggest that SIRT3 plays a role of protection in AngII-induced HUVECs dysfunction via regulation of ROS generation.

Cardiovascular-renal changes after kidney donation: one-year follow-up study

BACKGROUND

Long-term consequences of kidney donation are not well known. Most of the studies published were focused on renal risk. In this prospective study, we investigated the changes in cardiovascular function after kidney donation.

METHODS

Thirty-eight living kidney donors were included. In addition to 24-hr ambulatory blood pressure monitoring, serum interleukin-6, vascular cell adhesion molecule (VCAM), and asymmetric dimethylarginine levels were measured. Endothelial function was examined by measuring ischemia-induced flow-mediated dilation (FMD) of the brachial artery. All studies were repeated at 3 months and 12 months after kidney donation.

RESULTS

The mean serum interleukin-6 levels, both at 3 months and 12 months, were significantly increased as compared to the baseline (P = 0.007 and P < 0.001, respectively). The mean serum asymmetric dimethyl-arginine (P < 0.001) and VCAM levels (P < 0.001) at 12 months were significantly increased as compared to baseline. FMD values at 1 year (9.3% ± 7.1%) were significantly decreased as compared to 3 months (13.0% ± 6.0%, P = 0.001) and baseline (13.9% ± 6.3%, P = 0.002). In multivariate analysis, serum uric acid (P = 0.001), estimated glomerular filtration rate (P = 0.027), and VCAM (P = 0.014) levels were the independent predictors of FMD 12 months after kidney donation.

CONCLUSION

Our findings suggest that kidney donation might increase the cardiovascular risk in kidney donors.

The link between hypertension and pathological scarring: does hypertension cause or promote keloid and hypertrophic scar pathogenesis?

Pathological scars, namely, keloids and hypertrophic scars (HSs), are caused by excessive cutaneous wound healing that is characterized by histological extracellular matrix (ECM) accumulation, clinically relevant irritating symptoms, and frequent recurrence after surgical excision. To date, there are few effective and specific treatments. This partly reflects the poor understanding of the etiology of these scars and the lack of a suitable animal model. Systemic hypertension has been suggested to participate in pathological scarring. The evidence that supports this hypothesis is reviewed here. Thus, hypertension associates with changes that resemble the aberrant cutaneous wound-healing phases that characterize pathological scar development. It also associates with profibrotic functional changes in the cells that constitute keloids and HSs (endothelial cells, pericytes/myofibroblasts, dermal fibroblasts, and mast cells) and profibrotic ECM remodeling. These hypertension-associated changes are mediated to some extent by inflammation, hypoxia, and the angiotensin/renin-angiotensin-aldosterone system. Thus, hypertension may be an aggravating/risk factor for keloids and HSs. This will help to identify patients who are prone to heavy scars after surgery or postsurgical recurrence. Moreover, pharmacological agents for the prophylaxis and treatment of hypertension-induced fibrosis in other organs may also be useful for keloids/HSs.

Fibromuscular dysplasia presenting with asymptomatic bilateral renal infarctions

Fibromuscular dysplasia (FMD) is a noninflammatory nonatherosclerotic vascular disease. It is the second cause of renovascular hypertension after atherosclerosis. Although FMD usually has a good prognosis, renal infarctions and artery dissections have been described. We present the case of a 38-year-old woman with hypertension and asymptomatic bilateral renal infarctions. Bilateral FMD of segmental branches of the renal arteries was diagnosed by digital subtraction angiography after an exhaustive study. Previous intake of nonsteroidal anti-inflammatory drugs may also have played a significant role in the development of renal infarctions. To our knowledge, bilateral renal infarctions complicating FMD have been reported in only four previous cases; only in one of those cases, renal infarctions were asymptomatic.

The molecular mechanisms of offspring effects from obese pregnancy

The incidence of obesity, increased weight gain and the popularity of high-fat / high-sugar diets are seriously impacting upon the global population. Billions of individuals are affected, and although diet and lifestyle are of paramount importance to the development of adult obesity, compelling evidence is emerging which suggests that maternal obesity and related disorders may be passed on to the next generation by non-genetic means. The processes acting within the uteri of obese mothers may permanently predispose offspring to a diverse plethora of diseases ranging from obesity and diabetes to psychiatric disorders. This review aims to summarise some of the molecular mechanisms and active processes currently known about maternal obesity and its effect on foetal and neonatal physiology and metabolism. Complex and multifactorial networks of molecules are intertwined and culminate in a pathologically synergistic manner to cause disruption and disorganisation of foetal physiology. This altered phenotype may potentiate the cycle of intergenerational transmission of obesity and related disorders.

Disorders of erythrocyte structure and function in hypertensive patients

Background

The prevalence of hypertension is growing at an alarming rate. Increasing attention is being focussed on the oxidative stress accompanying this disease. In this study we examined the impact of this disease on some parameters of erythrocytes and human blood plasma.

Material/Methods

We examined the impact of hypertension on some parameters of erythrocytes and human plasma. The study involved 13 patients with hypertension and 19 healthy subjects. We determined lipid peroxidation, SH groups concentration, antioxidants enzymes activity, ATPase activity, total antioxidant capacity, total cholesterol level and erythrocyte membrane fluidity.

Results

We found an increased level of lipid peroxidation and the concentration of SH groups in membrane proteins in patients with hypertension, and a decrease in the activity of catalase and superoxide dysmutase. No changes were observed in glutathione peroxidase and ATPase activity, level of total antioxidant capacity, total cholesterol level and fluidity of erythrocyte membranes.

Conclusions

These results suggest the existence of an impaired oxidative balance in hypertensive human erythrocytes.

Prevention of diabetes-induced arginase activation and vascular dysfunction by Rho kinase (ROCK) knockout

AIMS

We determined the role of the Rho kinase (ROCK) isoforms in diabetes-induced vascular endothelial dysfunction and enhancement of arginase activity and expression.

METHODS AND RESULTS

Studies were performed in aortic tissues from haplo-insufficient (H-I) ROCK1 and ROCK2 mice and wild-type (WT) mice rendered diabetic with streptozotocin and in bovine aortic endothelial cells (BAECs) treated with high glucose (HG, 25 mM). Protein expression of both ROCK isoforms was substantially elevated in aortas of WT mice after 8 weeks of diabetes and in BAECs after 48 h in HG. Impairment of endothelium-dependent vasorelaxation of aortas was observed in diabetic WT mice. However, there was no impairment in aortas of diabetic ROCK1 H-I mice and less impairment in aortas of diabetic ROCK2 H-I mice, compared with non-diabetic mice. These vascular effects were associated with the prevention of diabetes-induced decrease in nitric oxide (NO) production and a rise in arginase activity/expression. Acute treatment with the arginase inhibitor, BEC, improved endothelium-dependent vasorelaxation of aortas of both diabetic WT and ROCK2, but not of ROCK1 mice.

CONCLUSION

Partial deletion of either ROCK isoform, but to a greater extent ROCK1, attenuates diabetes-induced vascular endothelial dysfunction by preventing increased arginase activity and expression and reduction in NO production in type 1 diabetes. Limiting ROCK and arginase activity improves vascular function in diabetes.

In vivo hypotensive and physiological effects of a silk fibroin hydrolysate on spontaneously hypertensive rats

A silk fibroin hydrolysate (SFH) exhibited a pronounced in vivo blood pressure-lowering effect on spontaneously hypertensive rats (SHRs) accompanied with decreases in the plasma angiotensin II, endothelin (ET), TNF-α and NO concentrations. We also observed a markedly decreased LPO level, a parameter of oxidative tissue damage, in the medium- and high-dose SFH-treated groups which was accompanied by an increased SOD level in erythrocytes. Our data suggest ACE inhibition together with an improved antioxidative status as the underlying antihypertensive mechanism for the silk fibroin hydrolysate. Since SFH could markedly lower the blood pressure and improve several physiological parameters involved in the occurrence of hypertension, it could be used as a possible supplement against cardiovascular diseases and as a functional food ingredient.

Inhibition of matrix metalloproteinase-2 improves endothelial function and prevents hypertension in insulin-resistant rats

BACKGROUND AND PURPOSE

Insulin resistance is often found to be associated with high blood pressure. We propose that in insulin-resistant hypertension, endothelial dysfunction is the consequence of increased activity of vascular MMP-2. As MMP-2 proteolytically cleaves a number of extracellular matrix proteins, we hypothesized that MMP-2 impairs endothelial function by proteolytic degradation of endothelial NOS (eNOS) or its cofactor, heat shock protein 90 (HSP90).

EXPERIMENTAL APPROACH

We tested our hypothesis in bovine coronary artery endothelial cells and fructose-fed hypertensive rats (FHR), a model of acquired systolic hypertension and insulin resistance.

KEY RESULTS

Treatment of FHRs with the MMP inhibitor doxycycline, preserved endothelial function as well as prevented the development of hypertension, suggesting that MMPs impair endothelial function. Furthermore, incubating endothelial cells in vitro with a recombinant MMP-2 decreased NO production in a dose-dependent manner. Using substrate cleavage assays and immunofluorescence microscopy studies, we found that MMP-2 not only cleaves and degrades HSP90, an eNOS cofactor but also co-localizes with both eNOS and HSP90 in endothelial cells, suggesting that MMPs functionally interact with the eNOS system. Treatment of FHRs with doxycycline attenuated the decrease in eNOS and HSP90 expression but did not improve insulin sensitivity.

CONCLUSIONS AND IMPLICATIONS

Our data suggest that increased activity of MMP-2 in FHRs impairs endothelial function and promotes hypertension. Inhibition of MMP-2 could be a potential therapeutic strategy for the management of hypertension.

Effects of statin treatment on endothelial function, oxidative stress and inflammation in patients with arterial hypertension and normal cholesterol levels

OBJECTIVE

Patients with arterial hypertension are characterized by impaired endothelial function and increased cardiovascular risk. Statins have been proposed as a potential treatment option in hypertension, even in those with normal low-density lipoprotein (LDL)-cholesterol levels. We tested whether fluvastatin reduces oxidative stress and inflammation, and improves endothelial function in patients with arterial hypertension and normal LDL-cholesterol.

METHODS

In a cross-over designed, double-blind randomized trial, 26 patients with arterial hypertension and LDL-cholesterol below 160 mg/dl were treated for 2 weeks with either placebo or fluvastatin 80 mg/day. Endothelium-dependent vasodilation (EDV) was assessed as the forearm blood flow (FBF) response to intra-arterial infusion of acetylcholine (ACH, 12 and 48 μg/min), and endothelium-independent vasodilation (EIV) as the FBF response to nitroprusside (3.2 and 12.8 μg/min). Furthermore, we measured reduced to oxidized glutathione (GSH/GSSG) ratio in red blood cells, total antioxidant capacity in plasma (TAC) and high-sensitivity C-reactive protein (hs-CRP) levels.

RESULTS

Fluvastatin lowered LDL-cholesterol from 118 ± 16 to 90 ± 25 mg/dl (P < 0.0001), but had no effect on blood pressure, high-density lipoprotein (HDL)-cholesterol or triglycerides. EDV and EIV were unaffected by fluvastatin treatment (e.g. increase of FBF 48 μg/min: 339 ± 285% during placebo versus 268 ± 194% during fluvastatin, n.s.). Finally, GSH/GSSG ratio, TAC and hs-CRP levels were similar between fluvastatin and placebo treatment.

CONCLUSION

Fluvastatin treatment did not improve endothelial function, oxidative stress or inflammation in patients with arterial hypertension and normal LDL-cholesterol levels. These data argue against the usefulness of statins in patients with arterial hypertension in the absence of hypercholesterolemia or other additional risk factors.

Augmentation index association with reactive hyperemia as assessed by peripheral arterial tonometry in hypertension

BACKGROUND

Augmentation pressure has emerged as a surrogate marker for cardiovascular disease, and endothelial dysfunction has been proposed as related factor. However, the relationship between augmentation pressure and digital endothelial function has not yet been well defined. We investigated the relationship between augmentation pressure and digital reactive hyperemia (RH) in patients with hypertension using peripheral arterial tonometry (PAT), which is regarded as being representative of endothelial function.

METHODS

One hundred hypertensive patients (64 males; mean age, 49 ± 12 years) without a history of taking antihypertensive medication were enrolled in this study.

RESULTS

The mean augmentation pressure and augmentation index (AIx) normalized for a heart rate of 75 beats/min (AIx75) were 15 ± 8 mm Hg and 26 ± 11%, respectively. The mean RH-PAT index and log transformed PAT ratio were 2.24 ± 0.55 and 0.62 ± 0.30. There was an inverse relationship between the RH-PAT index and age, male sex, and body mass index. The log transformed PAT ratio also showed inverse relationship with age and male sex. The RH-PAT index and the log transformed PAT ratio showed no relationship with augmentation pressure or AIx75. In a multiple linear regression analysis, age, height, and central systolic BP demonstrated an independent association with augmentation pressure and AIx75.

CONCLUSION

In patients with hypertension, the RH-PAT index determined using PAT was not associated with augmentation pressure or AIx75. Digital vascular function may be a less important factor for pressure augmentation in patients with hypertension.

A cross-sectional and 10-year prospective study of postmenopausal estrogen therapy and blood pressure, renal function, and albuminuria: the Rancho Bernardo Study

OBJECTIVE

Blood pressure, urine albumin-to-creatinine ratio, and estimated glomerular filtration rate (GFR) are highly correlated conditions. The longitudinal effect of exposure to postmenopausal estrogen therapy on these traits studied together has not been reported.

METHODS

This was a cross-sectional study of 1,044 older postmenopausal community-dwelling women from the Rancho Bernardo Study (1992-1996); 443 women were reevaluated ∼ 10 years later (2002-2005). We determined the cross-sectional and prospective association of baseline postmenopausal estrogen therapy and blood pressure, urine albumin-to-creatinine ratio, GFR, and the odds of categorical hypertension (physician diagnosis, medication, or blood pressure ≥ 140/≥ 90 mm Hg), chronic kidney disease (GFR ≤ 60 mL/min per 1.73 m2), and albuminuria (urine albumin-to-creatinine ratio ≥ 25 mg/g).

RESULTS

At baseline, the mean age was 68.3 years for current estrogen users, 75.4 years for past users, and 74.3 years for never users. In the cross-sectional analyses, current users had lower diastolic blood pressure and lower odds of having chronic kidney disease, independent of covariates. In the ∼ 10-year follow-up, comparisons between never, past, and current estrogen use (91% continuous use since baseline), the mean diastolic blood pressure declined over time in current users, whereas systolic blood pressure increased among never users. Urine albumin-to-creatinine ratio also increased in never users and decreased in current users; GFR did not differ by estrogen use.

CONCLUSIONS

In cross-sectional analyses, estrogen users had better GFR and blood pressure than nonusers did, but the 10-year follow-up showed improved blood pressure and decreased urine albumin-to-creatinine ratio among mostly long-term current users, without differences in GFR by estrogen use. This study suggests no association of GFR with 10 years of continuous estrogen use and an inverse association with albuminuria.

Exercise training alters the balance between vasoactive compounds in skeletal muscle of individuals with essential hypertension

The effects of physical training on the formation of vasodilating and vasoconstricting compounds, as well as on related proteins important for vascular function, were examined in skeletal muscle of individuals with essential hypertension (n=10). Muscle microdialysis samples were obtained from subjects with hypertension before and after 16 weeks of physical training. Muscle dialysates were analyzed for thromboxane A(2), prostacyclin, nucleotides, and nitrite/nitrate. Protein levels of thromboxane synthase, prostacyclin synthase, cyclooxygenase 1 and 2, endothelial nitric oxide synthase (eNOS), cystathionine-γ-lyase, cytochrome P450 4A and 2C9, and the purinergic receptors P2X1 and P2Y2 were determined in skeletal muscle. The protein levels were compared with those of normotensive control subjects (n=12). Resting muscle dialysate thromboxane A(2) and prostacyclin concentrations were lower (P<0.05) after training compared with before training. Before training, dialysate thromboxane A(2) decreased with acute exercise, whereas after training, no changes were found. Before training, dialysate prostacyclin levels did not increase with acute exercise, whereas after training there was an 82% (P<0.05) increase from rest to exercise. The exercise-induced increase in ATP and ADP was markedly reduced after training (P<0.05). The amount of eNOS protein in the hypertensive subjects was 40% lower (P<0.05) than in the normotensive control subjects, whereas cystathionine-γ-lyase levels were 25% higher (P<0.05), potentially compensating for the lower eNOS level. We conclude that exercise training alters the balance between vasodilating and vasoconstricting compounds as evidenced by a decrease in the level of thromboxane, reduction in the exercise-induced increase in ATP and a greater exercise-induced increase in prostacyclin.

The role of RhoA/Rho kinase pathway in endothelial dysfunction

Endothelial dysfunction is a key event in the development of vascular disease, and it precedes clinically obvious vascular pathology. Abnormal activation of the RhoA/Rho kinase (ROCK) pathway has been found to elevate vascular tone through unbalancing the production of vasodilating and vasoconstricting substances. Inhibition of the RhoA/ROCK pathway can prevent endothelial dysfunction in a variety of pathological conditions. This review, based on recent molecular, cellular, and animal studies, focuses on the current understanding of the ROCK pathway and its roles in endothelial dysfunction.

Oxidative stress and endothelial dysfunction in hypertension

Systemic arterial hypertension is a highly prevalent cardiovascular risk factor that causes significant morbidity and mortality, and is becoming an increasingly common health problem because of the increasing longevity and prevalence of predisposing factors such as sedentary lifestyle, obesity and nutritional habits. Further complicating the impact of this disease, mild and moderate hypertension are usually asymptomatic, and their presence (and the subsequent increase in cardiovascular risk) is often unrecognized. The pathophysiology of hypertension involves a complex interaction of multiple vascular effectors including the activation of the sympathetic nervous system, of the renin-angiotensin-aldosterone system and of the inflammatory mediators. Subsequent vasoconstriction and inflammation ensue, leading to vessel wall remodeling and, finally, to the formation of atherosclerotic lesions as the hallmark of advanced disease. Oxidative stress and endothelial dysfunction are consistently observed in hypertensive subjects, but emerging evidence suggests that they also have a causal role in the molecular processes leading to hypertension. Reactive oxygen species (ROS) may directly alter vascular function or cause changes in vascular tone by several mechanisms including altered nitric oxide (NO) bioavailability or signaling. ROS-producing enzymes involved in the increased vascular oxidative stress observed during hypertension include the NADPH oxidase, xanthine oxidase, the mitochondrial respiratory chain and an uncoupled endothelial NO synthase. In the current review, we will summarize our current understanding of the molecular mechanisms in the development of hypertension with an emphasis on oxidative stress and endothelial dysfunction.

Does Smoking Act as a Friend or Enemy of Blood Pressure? Let Release Pandora's Box

In spite of the great number of observations which show the certainty of cardiovascular damage from smoking, the opinions on that are not yet unanimous. There is a discrepancy that could be attributed to the lack of reproducible data particularly in some epidemiological studies. On the contrary, experimental findings conducted on both animals and humans give evidence of exactly reproducible results of cardiovascular alterations and among these the course of Blood Pressure (BP). Findings identify an increase in BP of active smokers or non-smokers exposed to passive smoking, while a lot of others refer a lowering of BP due to smoking. This discrepancy could be explained as follows. Initially, a vasoconstriction mediated by nicotine causes acute but transient increase in systolic BP. This phase is followed by a decrease in BP as a consequence of depressant effects played chronically by nicotine itself. Simultaneously, carbon monoxide is acting directly on the arterial wall causing, in the long run, structurally irreversible alterations. At this time, there is a change in BP that increases again, and often constantly, its levels following chronic exposure. Changes in response to antihypertensive drugs have been observed in hypertensive smokers since smoking influences metabolic steps of the drugs.

Statin treatment decreased serum asymmetric dimethylarginine (ADMA) levels in ischemic stroke patients

AIM

It remains unclear whether the decrease in the ADMA level associated with statin treatment results from the LDL-C-lowering effect or the pleiotropic effects of statins. A prospective, controlled study was conducted to examine whether statin treatment affects serum ADMA concentrations in ischemic stroke patients.

METHODS

Consecutive outpatients with non-cardiogenic ischemic stroke who had never been treated with statins and whose LDL-cholesterol level was higher than 140 mg/dL were enrolled and compared with control patients whose LDL-cholesterol level was lower than 140 mg/dL. Overall, 114 patients were enrolled in the study (56 and 58 in statin-treated and non-statin-treated groups, respectively). Patients in the statin group were treated with pravastatin 10 mg/day (n=15), fluvastatin 20 mg/day (n=14), pitavastatin 1 mg/day (n=14), or atorvastatin 10 mg/day (n=13).

RESULTS

The serum ADMA concentration and LDL-C level were significantly decreased by statin treatment (p=0.003 and p< 0.001, respectively), and the ADMA concentration in subjects treated with statins was significantly lower than that of the control (p=0.028). Multiple linear regression analysis showed that age (β=0.26, p< 0.05) and statin use (β=-0.20, p< 0.05) were independently associated with the ADMA level.

CONCLUSIONS

A significant relation between statin treatment and decreased levels of ADMA was demonstrated in ischemic stroke patients with an adequately controlled lipid profile, suggesting the statin treatment might prevent atherosclerotic disease in ischemic stroke patients through suppression of ADMA concentration.

Microvascular responses to cardiovascular risk factors

Hypertension, hypercholesterolemia, diabetes, and obesity are among a growing list of conditions that have been designated as major risk factors for cardiovascular disease (CVD). While CVD risk factors are well known to enhance the development of atherosclerotic lesions in large arteries, there is also evidence that the structure and function of microscopic blood vessels can be profoundly altered by these conditions. The diverse responses of the microvasculature to CVD risk factors include oxidative stress, enhanced leukocyte- and platelet-endothelial cell adhesion, impaired endothelial barrier function, altered capillary proliferation, enhanced thrombosis, and vasomotor dysfunction. Emerging evidence indicates that a low-grade systemic inflammatory response that results from risk factor-induced cell activation and cell-cell interactions may underlie the phenotypic changes induced by risk factor exposure. A consequence of the altered microvascular phenotype and systemic inflammatory response is an enhanced vulnerability of tissues to the deleterious effects of secondary oxidative and inflammatory stresses, such as ischemia and reperfusion. Future efforts to develop therapies that prevent the harmful effects of risk factor-induced inflammation should focus on the microcirculation.

Aerobic exercise acutely improves insulin- and insulin-like growth factor-1-mediated vasorelaxation in hypertensive rats

Limited information is available concerning the effects of aerobic exercise on vasorelaxation in hypertension. The aim of this study was to investigate the effects of a single bout of aerobic exercise on insulin- and insulin-like growth factor-1 (IGF-1)-induced vasorelaxation in hypertensive rats. Four-month-old spontaneously hypertensive rats were randomly divided into a sedentary group (SHR) and an exercise group (SHR+Ex) subjected to a single bout of aerobic exercise conducted by treadmill running at 21 m min(1) for 1 h. Age-matched Wistar-Kyoto rats were used as a normotensive control group (WKY). Insulin- and IGF-1-induced vasorelaxant responses in the three groups were evaluated by using isolated aortic rings, with or without endothelial denudation, in organ baths. Possible roles of phosphatidylinositol 3-kinase (PI3K) and nitric oxide synthase (NOS) involved in the NO-dependent vasorelaxation were examined by adding selective inhibitors. The role of superoxide was also clarified by adding superoxide dismutase (SOD). In addition, the endothelium-independent vascular responses to sodium nitroprusside (SNP), a NO donor, were examined. The insulin- and IGF-1-induced vasorelaxation was significantly (P < 0.05) decreased in the SHR group compared with the WKY group. This decreased response in SHR was improved by exercise. These vasorelaxant responses among the three groups became similar after endothelial denudation and pretreatment with the PI3K inhibitor, NOS inhibitor or SOD. Also, no difference among groups was found in the SNP-induced vasorelaxation. We concluded that a single bout of aerobic exercise acutely improves insulin- and IGF-1-mediated vasorelaxation in an endothelium-dependent manner in hypertensive rats.

Relationship between noninvasively measured endothelial function and peripheral arterial disease

OBJECTIVES

To determine the relationship between endothelial function by means of brachial artery flow-mediated dilation (BAFMD) and the clinical severity of peripheral arterial disease (PAD).

METHODS AND RESULTS

We examined the brachial artery diameter by ultrasound, before and after ischemia of the arm in 3 groups of participants- group A: healthy individuals under 30 years, without cardiovascular risk factors (n = 30); group B: patients with PAD and ischemic claudication (n = 30); and group C: patients with critical leg ischemia (n = 20). There were no differences between groups B and C, in regard to age, sex, and main cardiovascular risk factor. The BAFMD was 9.9% in group A compared with 5.5% in the pooled patients group (B + C; P < .001). Significant differences were absent between groups B and C (P > .05). Correlation coefficient of ankle-brachial index/BAFMD was r = .1; P = .49.

CONCLUSIONS

Patients with PAD present endothelial dysfunction, but this does not seem to determine the severity of the disease.

Lessons in hypertension from new clinical trials

Three important principles have emerged from recent epidemiologic and clinical studies in hypertension. First, patients with hypertension most often have other cardiovascular risk factors such as obesity and diabetes. Second, hypertension remains grossly undertreated. Third, at blood pressure levels once considered "high-normal," early organ damage may already be taking place in patients with multiple risk factors that, without treatment, can eventually lead to cardiovascular morbidity and mortality. The concept of evaluating global or overall risk is gaining wide acceptance, and US treatment guidelines may soon reflect these findings and assist clinicians in identifying individuals who are most likely to benefit from therapy. Results from clinical trials suggest that among the various pharmacologic agents available to treat hypertension, blockers of the renin-angiotensin system are effective in type 2 diabetes and chronic kidney disease, conditions that often occur in conjunction with hypertension.

Cholesterol induces renal vasoconstriction and anti-natriuresis by inhibiting nitric oxide production in anesthetized rats

Although hypercholesterolemia is implicated in the pathophysiology of many renal disorders as well as hypertension, its direct actions in the kidney are not yet clearly understood. In the present study, we evaluated renal responses to administration of cholesterol (8 microg x min(-1).100 g body wt(-1); bound by polyethylene glycol) into the renal artery of anesthetized male Sprague-Dawley rats. Total renal blood flow (RBF) was measured by a Transonic flow probe, and glomerular filtration rate (GFR) was determined by Inulin clearance. In control rats (n = 8), cholesterol induced reductions of 10 +/- 2% in RBF [baseline (b) 7.6 +/- 0.3 microg x min(-1).100 g(-1)], 17 +/- 3% in urine flow (b, 10.6 +/- 0.9 microg x min(-1).100 g(-1)), 29 +/- 3% in sodium excretion (b, 0.96 +/- 0.05 mumol.min(-1).100 g(-1)) and 24 +/- 2% in nitrite/nitrate excretion (b, 0.22 +/- 0.01 nmol.min(-1).100 g(-1)) without an appreciable change in GFR (b, 0.87 +/- 0.03 ml.min(-1).100 g(-1)). These renal vasoconstrictor and anti-natriuretic responses to cholesterol were absent in rats pretreated with nitric oxide (NO) synthase inhibitor, nitro-l-arginine methylester (0.5 microg x min(-1).100 g(-1); n = 6). In rats pretreated with superoxide (O(2)(-)) scavenger tempol (50 microg x min(-1).100 g(-1); n = 6), the cholesterol-induced renal responses remained mostly unchanged, although there was a slight attenuation in anti-natriuretic response. This anti-natriuretic response to cholesterol was abolished in furosemide-pretreated rats (0.3 microg x min(-1).100 g(-1); n = 6) but remained unchanged in amiloride-pretreated rats (0.2 microg x min(-1).100 g(-1); n = 5), indicating that Na(+)/K(+)/2Cl(-) cotransport is the dominant mediator of this effect. These data demonstrate that cholesterol-induced acute renal vasoconstrictor and antinatriuretic responses are mediated by a decrease in NO production. These data also indicate that tubular effect of cholesterol on sodium reabsorption is mediated by the furosemide sensitive Na(+)/K(+)/2Cl(-) cotransporter.

Endothelium-dependent contractions and endothelial dysfunction in human hypertension

The endothelium is a crucial regulator of vascular physiology, producing in healthy conditions several substances with a potent antiatherosclerotic properties. Accordingly, the presence of endothelial dysfunction is associated with subclinical atherosclerosis and with an increased future risk of cardiovascular events. A large body of evidence supports the fundamental role of nitric oxide (NO) as the main endothelium-derived relaxing factor. However, in the presence of pathological conditions, such as hypertension, endothelial cells, in response to a number of agents and physical stimuli, become also a source of endothelium-derived contracting factors (EDCFs), including endothelins and angiotensin II and particularly cyclooxygenase-derived prostanoids and superoxide anions. These latter were at first identified as responsible for impaired endothelium-dependent vasodilation in patients with essential hypertension. However, cyclooxygenase-dependent EDCFs production is characteristic of the aging process, and essential hypertension seems to only anticipate the phenomenon. It is worth noting that both in aging and hypertension EDCF production is associated with a parallel decrease in NO availability, suggesting that this substance could be oxygen free radicals themselves. Accordingly, in hypertension both indomethacin, a cyclooxygenase inhibitor, and vitamin C, an antioxidant, increase the vasodilation to acetylcholine by restoring NO availability. In conclusion, hypertension is characterized by a decline in endothelial function, associated with a progressive decrease in NO bioavailability and increase in the production of EDCF. The mechanisms that regulate the balance between NO and EDCF, and the processes transforming the endothelium from a protective organ to a source of vasoconstrictor, proaggregatory and promitogenic mediators remain to be determined.

Vascular reactivity is affected by dietary consumption of wild blueberries in the Sprague-Dawley rat

We have previously reported that consumption of blueberry-enriched (BB) diets attenuates the arterial contractile response to alpha(1)-adrenergic stimuli and affects vasomotor tone via endothelium-related pathways. The present study was designed to evaluate vascular function and responsiveness in aortas of weanling male Sprague-Dawley rats fed a control (C) or a BB diet for 7 weeks. Vascular ring studies were conducted in 3-mm isolated rat aortic ring preparations to investigate vasoconstriction induced by L-phenylephrine (Phe) (10(-8)-3 x 10(-6) M) and vasorelaxation induced by acetylcholine (ACh) (10(-8)-3 x 10(-6) M). Agonists were used alone and in the presence of nitric oxide (NO) synthase and cyclooxygenase (COX) inhibitors. We observed a significantly diminished vasoconstrictor response to Phe in aortic rings from rats fed the BB diet. Inhibition of NO synthase but not COX caused a significant increase in the constrictor response in both dietary groups, with the BB group having the greater response. Similarly, the participation of the NO pathway in endothelium-dependent vasorelaxation induced by ACh was greater in the rats fed a BB diet, while COX inhibition showed no effect on maximum ACh-induced vasorelaxation in any diet group. The vessel sensitivity of BB aortic rings to the vasoconstrictor and vasodilator was significantly reduced when compared to controls. We have concluded that diets enriched with blueberries, fed for 7 weeks in Sprague-Dawley rats, seem to affect NO metabolic pathways in the aorta at basal and stimulated levels.

Nitric oxide: link between endothelial dysfunction and inflammation in patients with peripheral arterial disease of the lower limbs

OBJECTIVES

To analyse the role of nitric oxide (NO) in peripheral arterial disease (PAD) and its association with inflammation and brachial artery flow-mediated dilation (BAFMD) as an estimation of endothelial dysfunction.

MATERIAL AND METHODS

Cross-sectional study of 82 patients with ischaemia (50 with Fontaine stage II and 32 with Fontaine stage III-IV) in whom BAFMD, hsCRP and nitrite levels in plasma were determined by colorimetric assay using the Griess reaction. They were compared with a control group of healthy subjects (n=41) with ABI >0.9, under 30 years of age.

RESULTS

No significant differences were found between the different stages of ischaemia in relation to risk factors or concomitant treatments. The patients with PAD had significantly higher NO levels in plasma than the control group (23.92+/-23.27 microM vs. 12.77+/-11.12 microM, P=0.001). However, no statistically significant differences were observed in the NO levels between the two groups of patients with PAD (25.24+/-24.47 microM vs. 21.86+/-19.86 microM, P=0.38). Neither were differences found between the two in BAFMD (4.7+/-4.2 vs. 4.3+/-2.8, P=0.1). The hsCRP values were statistically higher in PAD stage III-IV (8.2+/-13.5 vs. 29.2+/-33.2, P=0.0001).

CONCLUSIONS

The presence of elevated NO values in PAD, in conjunction with elevated CRP levels, reinforces the theory that atherosclerosis has an inflammatory nature. Its lack of correlation with the clinical severity, also occurring in BAFMD, lends weight to the hypothesis that endothelial dysfunction is an event which takes place in the first stages of the disease.

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.

Endothelial progenitor cells, endothelial dysfunction, inflammation, and oxidative stress in hypertension

With a prevalence in excess of 20%, hypertension is a common finding among Western adult populations. Hypertension is directly implicated in the pathophysiology of various cardiovascular disease states and is a significant contributor to ill health, leading to an excess of both morbidity and mortality. The etiology of hypertension has been explored in depth, but the pathophysiology is multifactorial, complex, and poorly understood. Recent interest has been directed toward investigating the purported role of the endothelium, which acts as an important regulator of vascular homeostasis. Endothelial dysfunction is now recognized to occur in hypertension, regardless of whether the etiology is essential or secondary to endocrine or renal processes. Nitric oxide (NO) is a volatile gas produced by endothelial cells that acts to maintain vascular tone. Reduced bioavailability of NO appears to be the key process through which endothelial dysfunction is manifested in hypertension. The result is of an imbalance of counteracting mechanisms, normally designed to maintain vascular homeostasis, leading to vasoconstriction and impaired vascular function. It has become increasingly apparent that these changes may be effected in response to enhanced oxidative stress, possibly as a result of systemic and localized inflammatory responses. This article provides an overview of endothelial dysfunction in hypertension and focuses on the purported role of oxidative stress and inflammation as the catalysts for this process.

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.

Synergistic effect of amlodipine and atorvastatin in reversing LDL-induced endothelial dysfunction

PURPOSE

Statins and certain calcium channel blockers may improve nitric oxide (NO) release and endothelial function through various mechanisms, but their combined effects are not well understood.

METHODS

The separate versus combined effects of amlodipine (AML) and atorvastatin (AT) on NO and peroxynitrite (ONOO-) were measured in human umbilical vein endothelial cells (HUVEC) in the presence and absence of low-density lipoprotein (LDL) using electrochemical nanosensors.

RESULTS

The combination of AML (5 micromol/l) and AT (3-6 micromol/l) directly stimulated NO release that was about twofold greater than the sum of their separate effects (p < 0.05). This synergistic activity is attributed to enhanced endothelial NO synthase (eNOS) function and decreased cytotoxic ONOO-. LDL (100 mg/dl) caused a dysfunction of HUVEC manifested by a 60% reduction in NO and an almost twofold increase in ONOO-. Treatment with AML/AT partially reversed the effects of LDL on endothelial function, including a 90% increase in NO and 50% reduction in ONOO-. Small-angle X-ray diffraction analysis indicates that AML and AT are lipophilic and share an overlapping molecular location in the cell membrane that could facilitate electron transfer for antioxidant mechanisms.

CONCLUSION

These findings indicate a synergistic effect of AML and AT on an increase in NO concentration, reduction of nitroxidative stress. Also, AML/AT partially restored the NO level of LDL-induced dysfunctional endothelium. Their combined effects may be enhanced by antioxidant properties related to their intermolecular actions in the cell membrane and an increase in the expression and coupling of endothelial nitric oxide synthase.

A change in the redox environment and thromboxane A2 production precede endothelial dysfunction in mice

We reported that the endothelial dysfunction that develops with age was associated with a proinflammatory phenotype. In this study, we hypothesized that an increased production of proinflammatory cyclooxygenase (COX) products occurs before endothelial dysfunction. Dilations to acetylcholine (ACh) were recorded from pressurized renal arteries isolated from 3- and 6-mo-old C57Bl/6 male mice treated or not with the polyphenol catechin (30 mg·kg−1·day−1) in drinking water for 3 mo. Release of thromboxane (TX) B2, the metabolite of TXA2, was measured by using immunoenzymatic assays, and free radical production was measured by using the fluorescent dye CM-H2DCFDA. Endothelial nitric oxide synthase (eNOS) and COX-1/2 mRNA expression were quantified by quantitative PCR. NG-nitro-l-arginine (l-NNA) reduced ( P < 0.05) ACh-induced dilation in vessels isolated from 3- and 6-mo-old mice. In the presence of l-NNA, indomethacin normalized ( P < 0.05) the dilation in vessels from 6-mo-old mice only. SQ-29548 (PGH2/TXA2 receptor antagonist) and furegrelate (TXA2 synthase inhibitor), in the presence of l-NNA, also improved ( P < 0.05) dilation. l-NNA increased TXA2 release and free radical-associated fluorescence, the latter being prevented by SQ-29548. In vessels from 6-mo-old mice treated with catechin for 3 mo, l-NNA-dependent reduction in ACh-mediated dilation was insensitive to indomethacin, whereas TXA2 release and free radical-associated fluorescence were prevented. eNOS mRNA expression was significantly increased by catechin treatment. Our results suggest that an augmented production of TXA2 and the associated change in redox regulation precede the development of the endothelial dysfunction.

Nitric-oxide synthase: A cytochrome P450 family foster child

Nitric-oxide synthase (NOS), the enzyme responsible for mammalian NO generation, is no cytochrome P450, but there are striking similarities between both enzymes. First and foremost, both are heme-thiolate proteins, employing the same prosthetic group to perform similar chemistry. Moreover, they share the same redox partner, a diflavoprotein reductase, which in the case of NOS is incorporated with the oxygenase in one polypeptide chain. There are, however, also conspicuous differences, such as the presence in NOS of the additional cofactor tetrahydrobiopterin, which is applied as an auxiliary electron donor to prevent decay of the oxyferrous complex to ferric heme and superoxide. In this review similarities and differences between NOS and cytochrome P450 are analyzed in an attempt to explain why NOS requires BH4 and why NO synthesis is not catalyzed by a member of the cytochrome P450 family.

Endothelial dysfunction and the kidney: emerging risk factors for renal insufficiency and cardiovascular outcomes in essential hypertension

Renal insufficiency in essential hypertension represents the expression of a medium- and small-size arteriolopathy characterized by intimal hyperplasia, hyalinosis, and smooth muscle cell hypertrophy (nephroangiosclerosis). Because in animal models endothelial dysfunction plays a role in this alteration, nephroangiosclerosis and the attendant renal insufficiency may be the expression of a systemic dysfunction of vascular endothelium. Endothelial function in the kidney vasculature of hypertensive individuals has been investigated little because studies on the hemodynamic response of the kidney to nitric oxide activation and blockade are laborious to perform. There is no direct proof that endothelial dysfunction in the forearm or in the coronary circulation is paralleled by a similar hemodynamic dysfunction in the kidney. A recent study in a large population of patients with essential hypertension showed that, independent of other risk factors, the GFR in these patients is strongly related to the forearm blood flow response to acetyl choline (an established test of endothelial function). Furthermore, in this study, C-reactive protein was inversely related to the GFR and with the vasodilatory response to acetyl choline, pointing to inflammation as a likely mechanism to explain the association between endothelial dysfunction and impaired renal function in essential hypertension. A dysfunctional endothelium may represent a critical link accounting for the risk for both renal impairment and cardiovascular complications in essential hypertension.