Effect of the angiotensin-converting enzyme inhibitor imidapril on reactive hyperemia in patients with essential hypertension: relationship between treatment periods and resistance artery endothelial function

A network meta-analysis comparative the efficacy of angiotensin-converting enzyme inhibitors and calcium channel blockers in hypertension

BACKGROUND

Currently, most studies primarily focus on directly comparing the efficacy and safety of angiotensin-converting enzyme inhibitors (ACEIs) and calcium channel blockers (CCBs), the two major classes of antihypertensive drugs. Moreover, the majority of studies are based on randomized controlled trials and traditional meta-analyses, with few exploring the efficacy and safety comparisons among various members of ACEIs and CCBs.

METHODS

ACEIs and CCB were searched for in randomized controlled trials in CNKI, Wanfang, VIP, China Biology Medicine Disc (Si-noMed), PubMed, EMbase, and Cochrane Library databases. The search can be conducted till November 2022. Stata software (version 16.0) and R 4.1.3 was used for statistical analysis and graphics plotting, applying mvmeta, gemtc, and its packages. Meta-regression analysis was used to explore the inconsistencies of the studies.

RESULTS

In 73 trials involving 33 different drugs, a total of 9176 hypertensive patients were included in the analysis, with 4623 in the intervention group and 4553 in the control group. The results of the analysis showed that, according to the SUCRA ranking, felodipine (MD = -12.34, 95% CI: -17.8 to -6.82) was the drug most likely to be the best intervention for systolic blood pressure, while nitrendipine (MD = -8.01, 95% CI: -11.71 to -4.18) was the drug most likely to be the best intervention for diastolic blood pressure. Regarding adverse drug reactions, nifedipine (OR = 0.32, 95% CI: 0.14-0.74) was the drug most likely to be the safest.

CONCLUSION

The research findings indicate that nifedipine is the optimal intervention for reducing systolic blood pressure in hypertensive patients, nitrendipine is the optimal intervention for reducing diastolic blood pressure in hypertensive patients, and felodipine is the optimal intervention for safety.

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.

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.

[Pathogenesis of endothelial dysfunction in cerebral atherosclerosis and their correction]

The authors review the studies on oxidative stress in the pathogenesis of cerebrovascular diseases (CVD) and highlight a contribution of endothelial dysfunction to the CVD development. Own experience of using divasa in patients of old and very old age with chronic CVD comorbid to cerebral atherosclerosis is described.

Pharmacotherapies and their influence on asymmetric dimethylargine (ADMA)

Elevated plasma concentrations of the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA) are found in various clinical settings, including renal failure, coronary heart disease, hypertension, diabetes and pre eclampsia. In healthy people acute infusion of ADMA promotes vascular dysfunc tion, and in mice chronic infusion of ADMA promotes progression of atherosclerosis. Thus, ADMA may not only be a marker but also an active player in cardiovascular disease, which makes it a potential target for therapeutic interventions. This review provides a summary and critical discussion of the presently available data concern ing the effects on plasma ADMA levels of cardiovascular drugs, hypoglycemic agents, hormone replacement therapy, antioxidants, and vitamin supplementation. We assess the evidence that the beneficial effects of drug therapies on vascular func tion can be attributed to modification of ADMA levels. To develop more specific ADMA-lowering therapies, mechanisms leading to elevation of plasma ADMA con centrations in cardiovascular disease need to be better understood. ADMA is formed endogenously by degradation of proteins containing arginine residues that have been methylated by S-adenosylmethionine-dependent methyltransferases (PRMTs). There are two major routes of elimination: renal excretion and enzymatic degrada tion by the dimethylarginine dimethylaminohydrolases (DDAH-1 and -2). Oxidative stress causing upregulation of PRMT expression and/or attenuation of DDAH activity has been suggested as a mechanism and possible drug target in clinical conditions associated with elevation of ADMA. As impairment of DDAH activity or capacity is associated with substantial increases in plasma ADMA concentrations, DDAH is likely to emerge as a prime target for specific therapeutic interventions.

The effects of alpha 1-adrenoceptor blockade and angiotensin converting enzyme inhibition on central and brachial blood pressure and vascular reactivity: the doxazosin-ramipril study

We aimed to study whether inhibition of the renin–angiotensin–aldosterone system has effects on vascular structure and function beyond the effects on blood pressure reduction alone. Patients with mild-to-moderate hypertension (n = 61, age 54 ± 12 years, 34% women) received the angiotensin converting enzyme inhibitor ramipril 10 mg or the alpha 1-adrenoceptor blocker doxazosin 8 mg double-blind for 12 weeks. Aortic blood pressure, pulse wave velocity, and augmentation index were assessed by applanation tonometry. Endothelial function was studied by forearm post-ischemic flow mediated vasodilatation and by pulse wave analysis with beta 2-adrenoceptor agonist stimulation. Skin microvascular reactivity was assessed by laser Doppler fluxmetry and iontophoresis. Treatment with doxazosin or ramipril reduced aortic and brachial blood pressures (all P < 0.001), with greater reductions in aortic than brachial systolic blood pressures (P = 0.021) and aortic/brachial pulse pressure ratio (P = 0.005). Compared to doxazosin, ramipril reduced carotid-femoral and carotid-radial pulse wave velocity (both P < 0.05). Forearm endothelial dependent and independent vasodilatation, assessed by post-ischemic flow mediated vasodilatation and glyceryl trinitrate, and by pulse wave analysis remained unchanged by both doxazosin and ramipril. In addition, skin microvascular endothelial dependent (acetylcholine) and independent vasodilatation (sodium nitroprusside) remained unchanged. In conclusion, ramipril reduced indices of aortic stiffness, suggesting that angiotensin converting enzyme inhibitor therapy may have effects beyond blood pressure reduction. However, treatment did not appear to influence endothelial function. Evidence of endothelial dysfunction and its possible improvement by antihypertensive treatment might require more advanced hypertension.

This study is registered at ClinicalTrials.gov (NCT02901977) and at EudraCT (# 2007-000631-25).

Microvascular Dilator Function in Athletes: A Systematic Review and Meta-analysis

PURPOSE

Despite the growing research interest in vascular adaptations to exercise training over the last few decades, it remains unclear whether microvascular function in healthy subjects can be further improved by regular training. Herein, we sought to systematically review the literature and determine whether microvascular dilator function is greater in athletes compared to age-matched healthy untrained subjects.

METHODS

We conducted a systematic search of MEDLINE, Cochrane, EMBASE, and Web of Science since their inceptions until October 2013 for articles evaluating indices of primarily microvascular endothelium-dependent or endothelium-independent dilation (MVEDD and MVEID, respectively) in athletes. A meta-analysis was performed to determine the standardized mean difference (SMD) in MVEDD and MVEID between athletes and age-matched controls. Subgroup analyses were used to study potential moderating factors.

RESULTS

Thirty-six studies were selected after systematic review, comprising 521 athletes (506 endurance-trained and 15 endurance- and strength-trained) and 496 age-matched control subjects. After data pooling, athletes presented higher MVEDD (31 studies; SMD, 0.47; P < 0.00001) and MVEID (14 studies; SMD, 0.51; P < 0.00001) compared with the control subjects. Similar results were observed in young (younger than 40 yr) and master (older than 55 yr) athletes when analyzed separately.

CONCLUSION

Both young and master athletes present enhanced microvascular function compared with age-matched untrained but otherwise healthy subjects. These data provide evidence of a positive association between exercise training and microvascular function in the absence of known underlying cardiovascular disease.

Prolonged postocclusive hyperemia response in patients with normal-tension glaucoma

Background

It is believed that endothelial dysfunction may be a link between systemic and ocular dysregulation in glaucoma. The aim of this study was to evaluate peripheral vascular reactive hyperemia in response to occlusion test and to correlate peripheral vascular findings with retrobulbar hemodynamics parameters in patients with normal-tension glaucoma.

Material/Methods

Forty-eight patients with normal-tension glaucoma (mean age 58.1 years, 38 women) and 40 control subjects (mean age 54.1 years, 36 women) were subjected to a brachial arterial occlusion test and color Doppler imaging (LOGIQ 9, GE Medical Systems) of the retrobulbar arteries. Finger hyperemia was assessed by using a 2-channel laser Doppler flowmeter (MBF-3D, Moor Instruments, Ltd.). Time parameters (time to peak flow, half-time of hyperemia, time of recovery) and amplitude parameters (maximum hyperemia response, biological zero) of the post-occlusive reactive hyperemia signal pattern as well as velocities and resistance index of the ophthalmic, central retinal, and short posterior ciliary arteries were evaluated and compared between study groups.

Results

In glaucoma patients, time to peak flow and half-time of hyperemia were significantly longer (21.4 vs. 12.0 s, p=0.02 and 74.1 vs. 44.2 s, p=0.03, respectively) and biological zero was significantly lower (2.4 vs. 3.2, p=0.01) comparing with healthy subjects. In glaucoma patients, peak-systolic and end-diastolic velocities of central retinal artery were significantly lower (12.8 vs.14.1, p=0.03 and 3.9 vs. 4.7, p=0.01, respectively) and resistance index of this artery was significantly higher (0.69 vs. 0.67, p=0.03) compared to controls. In the glaucoma group, maximum hyperemic response was negatively correlated with the resistance index of temporal short posterior ciliary arteries (r=−0.4, p=0.01), whereas in the control group half-time of hyperemia was negatively correlated with end-diastolic velocity of the central retinal artery (r=−0.3, p=0.03).

Conclusions

Arterial occlusion test elicited a prolonged systemic hyperemia response in patients with glaucoma as compared with healthy subjects. Retrobulbar blood flow alterations in glaucoma patients may be related to systemic vascular dysregulation.

Ultrasound assessment of endothelial-dependent flow-mediated vasodilation of the brachial artery in clinical research

The vascular endothelium is a monolayer of cells that cover the interior of blood vessels and provide both structural and functional roles. The endothelium acts as a barrier, preventing leukocyte adhesion and aggregation, as well as controlling permeability to plasma components. Functionally, the endothelium affects vessel tone. Endothelial dysfunction is an imbalance between the chemical species which regulate vessel tone, thombroresistance, cellular proliferation and mitosis. It is the first step in atherosclerosis and is associated with coronary artery disease, peripheral artery disease, heart failure, hypertension, and hyperlipidemia. The first demonstration of endothelial dysfunction involved direct infusion of acetylcholine and quantitative coronary angiography. Acetylcholine binds to muscarinic receptors on the endothelial cell surface, leading to an increase of intracellular calcium and increased nitric oxide (NO) production. In subjects with an intact endothelium, vasodilation was observed while subjects with endothelial damage experienced paradoxical vasoconstriction. There exists a non-invasive, in vivo method for measuring endothelial function in peripheral arteries using high-resolution B-mode ultrasound. The endothelial function of peripheral arteries is closely related to coronary artery function. This technique measures the percent diameter change in the brachial artery during a period of reactive hyperemia following limb ischemia. This technique, known as endothelium-dependent, flow-mediated vasodilation (FMD) has value in clinical research settings. However, a number of physiological and technical issues can affect the accuracy of the results and appropriate guidelines for the technique have been published. Despite the guidelines, FMD remains heavily operator dependent and presents a steep learning curve. This article presents a standardized method for measuring FMD in the brachial artery on the upper arm and offers suggestions to reduce intra-operator variability.

Effect of antioxidant vitamin supplementation on endothelial function in type 2 diabetes mellitus: a systematic review and meta-analysis of randomized controlled trials

Controversy exists among trials assessing whether prolonged antioxidant vitamin supplementation improves endothelial function in type 2 diabetes mellitus (T2DM) subjects. The aim of this study was to systematically review and quantify the effect of antioxidant vitamin supplementation on endothelial function in T2DM subjects. MEDLINE, Cochrane, Scopus and Web of Science were searched up to February 2013 for randomized controlled trials assessing the effect of antioxidant vitamin E and/or C supplementation on endothelial function in T2DM subjects. Ten randomized controlled trials comparing antioxidant vitamin-supplemented and control groups (overall n = 296) met the inclusion criteria. Post-intervention standardized mean difference (SMD) in endothelial function did not reach statistical significance between groups (0.35; 95% confidence interval = -0.17, 0.88; P = 0.18). In subgroup analysis, post-intervention endothelial function was significantly improved by antioxidant vitamin supplementation in T2DM subgroups with body mass index (BMI) ≤ 29.45 kg m(-2) (SMD = 1.02; P < 0.05), but not in T2DM subgroups with BMI > 29.45 kg m(-2) (SMD = -0.07; P = 0.70). In meta-regression, an inverse association was found between BMI and post-intervention SMD in endothelial function (B = -0.024, P = 0.02). Prolonged antioxidant vitamin E and/or C supplementation could be effective to improve endothelial function in non-obese T2DM subjects.

Differential effects of aliskiren/amlodipine combination and high-dose amlodipine monotherapy on endothelial function in elderly hypertensive patients

BACKGROUND

The aim of this study was to compare the effects of direct renin inhibitor, aliskiren, and amlodipine combination therapy with those of high-dose amlodipine monotherapy on endothelial function in elderly hypertensive patients.

METHODS

Participants included 105 patients (mean age 77 years) who had receive 5mg amlodipine for 4 weeks. Patients were allocated to the aliskiren/amlodipine group (AL/AM) or the high-dose amlodipine (AM) group. The AL/AM group received 150mg aliskiren in addition to 5mg amlodipine for 8 weeks; then the dose of aliskiren was doubled to 300mg for another 8 weeks. The AM group received 10mg amlodipine for 16 weeks. Of the 105 patients, 87 who underwent measurements of brachial flow-mediated vasodilation (FMD) and nitroglycerin-mediated vasodilation (NMD) before and after the study were included in the analysis.

RESULTS

Blood pressure-lowering effects were similar in the 2 groups. Plasma renin activity significantly decreased in the AL/AM group (P < 0.001) but increased in the AM group (P < 0.001). Improvement of FMD was found in the AL/AM group (2.6% to 3.7%, P = 0.001) but not in the AM group, while NMD did not change in either group. The changes in 24-hour systolic blood pressure (r = -0.60, P < 0.001) and diastolic blood pressure (r = -0.46, P = 0.004) were significantly correlated with improvement of FMD in the AL/AM group but not in the AM group.

CONCLUSION

Addition of aliskiren improved endothelial function in elderly hypertensive patients treated with amlodipine.

CLINICAL TRIAL REGISTRY NUMBER

UMIN000010163.

Endothelium-dependent relaxations in the aorta from K(2p)6.1 knockout mice

K2P6.1 or TWIK-2, a two-pore domain K channel, is an important regulator of cardiovascular function. K2P6.1 is highly expressed in vascular smooth muscle and endothelium. Mice (8-12 wk) lacking functional K2P6.1 (K2P6.1(-/-)) are hypertensive and have enhanced vascular contractility. It is not known whether the lack of functional K2P6.1 in endothelium has a role in the vascular dysfunction in K2P6.1(-/-) mice. We tested the hypothesis: K2P6.1(-/-) mice have impaired endothelium-dependent relaxations. K2P6.1(-/-) mice were ∼35 mmHg more hypertensive than WT mice at both 8-12 wk (young adult) and 20-24 wk (mature mice, P < 0.01; n = 8-10). Endothelium-dependent relaxations of the thoracic aorta were evaluated by isometric myography after contraction with phenylephrine (10(-6) M). Maximal ACh-dependent relaxations were increased from 65 ± 1% to 73 ± 1% in the aorta from young adult (P < 0.01; n = 6) and from 45 ± 1% to 74 ± 1% in the aorta from mature (P < 0.001; n = 5) K2P6.1(-/-) mice compared with K2P6.1(+/+) littermates. However, in the aorta from young adult and mature K2P6.1(+/+) mice, 10(-5) M indomethacin, a cyclooxygenase inhibitor, increased maximal ACh relaxations to knockout levels. Enhanced relaxation was also seen with ATP, a P2Y purinergic agonist, and A23187, a nonreceptor-based agonist in mature K2P6.1(-/-) mice. Mature adult aorta from K2P6.1(-/-) showed an attenuated ACh-mediated contraction in the presence of nitro-l-arginine methyl ester (l-NAME) and without precontraction of 0.97 mN vs. 7.5 mN in K2P6.1(-/-) and K2P6.1(+/+) (P < 0.001; n = 5). In summary, K2P6.1(-/-) mice, which are hypertensive, have enhanced endothelium-dependent relaxations in the aorta due to the suppression of an indomethacin-sensitive constrictor component.

Endothelial dysfunction and hypertension in aging

Hypertension is one of the common diseases in the elderly. The prevalence of hypertension markedly increases with advancing age. Both aging and hypertension have a critical role in cardiovascular and cerebrovascular complications. Although aging and hypertension, either independently or collectively, impair endothelial function, aging and hypertension may have similar cascades for the pathogenesis and development of endothelial dysfunction. Nitric oxide (NO) has an important role in regulation of vascular tone. Decrease in NO bioavailability by endothelial dysfunction would lead to elevation of blood pressure. An imbalance of reduced production of NO or increased production of reactive oxygen species, mainly superoxide, may promote endothelial dysfunction. One possible mechanism by which the prevalence of hypertension is increased in relation to aging may be advancing endothelial dysfunction associated with aging through an increase in oxidative stress. In addition, endothelial cell senescence is also involved in aging-related endothelial dysfunction. In this review, we focus on recent findings and interactions between endothelial function, oxidative stress and hypertension in aging.

Continuous positive airway pressure therapy improves vascular dysfunction and decreases oxidative stress in patients with the metabolic syndrome and obstructive sleep apnea syndrome

BACKGROUND

Patients with obstructive sleep apnea syndrome (OSAS) are always exposed to intermittent hypoxia and reoxygenation. The metabolic syndrome (MetS) and OSAS are also known to accelerate atherosclerosis, diabetes, and dyslipidemia. Therefore, nasal continuous positive airway pressure (CPAP) therapy may have beneficial effects in patients with the MetS and OSAS.

HYPOTHESIS

This study in patients with the MetS and OSAS tested the validity of the hypothesis that chronic CPAP therapy improves factors involved in atherosclerosis, including impaired endothelial function.

METHODS

Thirty-two patients (19 males and 13 females, mean age 54 ± 9 y) diagnosed with the MetS and OSAS were enrolled in the study and received CPAP therapy for 3 months. Vascular function was investigated by measuring forearm blood flow (FBF) responses to reactive hyperemia (RH) using venous occlusion strain-gauge plethysmography. Biochemical markers were also measured before and after this procedure.

RESULTS

Basal apnea-hypopnea index was statistically correlated with FBF response to RH. The FBF response to RH was increased significantly after 3 months of CPAP therapy. A significant increase in plasma nitric oxide levels and a decrease in the levels of asymmetrical dimethylarginine, thiobarbituric acid reactive substance, soluble Fas ligand, and soluble CD40 ligand were detected after CPAP therapy. The plasma concentrations of tumor necrosis factor-α, interleukin (IL)-6, and IL-8 also decreased significantly with CPAP therapy, whereas IL-1β levels remained unchanged.

CONCLUSIONS

Continuous positive airway pressure therapy has beneficial effects on vascular function and inflammatory and oxidative stress in patients with the MetS and OSAS.

The Role of Asymmetric Dimethylarginine (ADMA) in Endothelial Dysfunction and Cardiovascular Disease

Endothelium plays a crucial role in the maintenance of vascular tone and structure. Endothelial dysfunction is known to precede overt coronary artery disease. A number of cardiovascular risk factors, as well as metabolic diseases and systemic or local inflammation cause endothelial dysfunction. Nitric oxide (NO) is one of the major endothelium derived vaso-active substances whose role is of prime importance in maintaining endothelial homeostasis. Low levels of NO are associated with impaired endothelial function. Asymmetric dimethylarginine (ADMA), an analogue of L-arginine, is a naturally occurring product of metabolism found in human circulation. Elevated levels of ADMA inhibit NO synthesis and therefore impair endothelial function and thus promote atherosclerosis. ADMA levels are increased in people with hypercholesterolemia, atherosclerosis, hypertension, chronic heart failure, diabetes mellitus and chronic renal failure. A number of studies have reported ADMA as a novel risk marker of cardiovascular disease. Increased levels of ADMA have been shown to be the strongest risk predictor, beyond traditional risk factors, of cardiovascular events and all-cause and cardiovascular mortality in people with coronary artery disease. Interventions such as treatment with L-arginine have been shown to improve endothelium-mediated vasodilatation in people with high ADMA levels. However the clinical utility of modifying circulating ADMA levels remains uncertain.

Novel therapeutic strategies targeting vascular endothelium in essential hypertension

IMPORTANCE OF THE FIELD

Several studies have demonstrated the high prevalence of hypertension and the crucial role of the association between endothelial function and hypertension. Thus, in depth investigation of the pathophysiological mechanisms linking endothelial dysfunction and hypertension, as well as evaluation of the efficacy of therapeutic approaches targeting vascular endothelium in states of essential hypertension seems to be of great interest.

AREAS COVERED IN THIS REVIEW

The association of essential hypertension and endothelial function are discussed in depth. In addition to the classical anti-hypertensive agents, agents such as statins, tetrahydrobiopterin, l-arginine, antioxidants, sildenafil, third generation beta blockers and NO-release related agents have been found to be beneficial by improving endothelial dysfunction in essential hypertension.

WHAT THE READER WILL GAIN

Important aspects regarding the association of hypertension and endothelial dysfunction will be highlighted. In addition, classical and novel agents especially, will be reported thoroughly according to their effects on endothelial function in hypertension.

TAKE HOME MESSAGE

There is a strong bidirectional association between essential hypertension and endothelial dysfunction. Moreover, novel agents appear to be beneficial and promising in improving endothelial function in states of hypertension. However, more studies are required to evaluate their role, as the literature lacks large scale studies.

Upregulation of ecto-5'-nucleotidase by rosuvastatin increases the vasodilator response to ischemia

3-Hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitors (statins) are effective in the primary and secondary prevention of cardiovascular events. Although originally developed to improve lipid profile, statins have demonstrated a surplus of beneficial pleiotropic effects, including improved endothelial function, reduced inflammation, and increased tolerance to ischemia-reperfusion injury. In preclinical studies, increased ecto-5'-nucleotidase activity, the key enzyme in extracellular adenosine formation, plays an important role in these effects. Because human data are absent, we explored the effects of rosuvastatin on ecto-5'-nucleotidase activity and the clinical relevance of increased extracellular adenosine during ischemia in humans in vivo. The forearm vasodilator responses to 3 increasing periods of forearm ischemia (2, 5, and 13 minutes) were determined during placebo and caffeine (an adenosine receptor antagonist) infusion into the brachial artery. At the end of an 8-day treatment period with rosuvastatin (20 mg per day), this whole procedure was repeated. During both experiments, ecto-5'-nucleotidase activity was determined. Vasodilator responses are expressed as the percentage increase in forearm blood flow ratio from baseline. Rosuvastatin increased ecto-5'-nucleotidase activity by 49±17% and enhanced the vasodilator response after 2, 5, and 13 minutes of ischemia in the absence (146±19, 330±26, and 987±133 to 312±77, 566±107, and 1533±267) but not in the presence of caffeine (98±25, 264±54, and 727±111 versus 95±19, 205±34, and 530±62). Rosuvastatin increases extracellular formation of adenosine in humans in vivo probably by enhancing ecto-5'-nucleotidase activity. This action results in the improvement of reactive hyperemia and may further enhance the clinical benefit of statins, in particular in conditions of ischemia.

The activation of endothelin-1 pathway during methionine-induced homocysteinemia mediates endothelial dysfunction in hypertensive individuals

OBJECTIVES

Endothelin-1 (ET-1) is a key regulator of arterial blood pressure in humans, and homocysteinemia is associated with increased oxidative stress. It is still unclear whether homocysteine-induced oxidative stress is implicated in the regulation of ET-1 expression. We examined the impact of acute homocysteinemia on endothelial function in hypertensive patients and healthy individuals, and the potential role of ET-1.

METHODS

In this double-blind, placebo-controlled study, 39 hypertensive and 49 healthy individuals were randomized to receive high-dose vitamins (2 g vitamin C and 800IU vitamin E) or placebo followed by methionine loading 100 mg/kg body weight. Endothelium-dependent dilation (EDD) and endothelium-independent dilation (EID) of the brachial artery were evaluated by plethysmography, at baseline and 4 h postloading (4 h PML). ET-1 was measured by ELISA, whereas total lipid hydroperoxides (per-ox) levels were measured by a commercially available photometric technique.

RESULTS

Acute, methionine-induced homocysteinemia decreased EDD in all study groups (P < 0.001 for all), whereas vitamins pretreatment failed to prevent this effect, despite the vitamins-induced reduction of peroxidation in the hypertensives group (P < 0.05). On the contrary, methionine loading significantly increased plasma ET-1 levels only in hypertensives (P < 0.05), an effect which was not prevented by antioxidant vitamins (P < 0.05). EID remained unchanged after methionine loading, in all study groups (P = NS for all groups).

CONCLUSION

Experimental homocysteinemia rapidly blunts endothelial function in both hypertensive individuals and healthy individuals. The rapid elevation of ET-1 levels observed only in hypertensives, suggests that ET-1 may be the key mediator of homocysteine-induced endothelial dysfunction, independently of oxidative stress.

Renin-angiotensin system activation correlates with microvascular dysfunction in a prospective cohort study of clinical sepsis

Introduction

Microvascular dysregulation characterized by hyporesponsive vessels and heterogeneous bloodflow is implicated in the pathogenesis of organ failure in sepsis. The renin-angiotensin system (RAS) affects the microvasculature, yet the relationships between RAS and organ injury in clinical sepsis remain unclear. We tested our hypothesis that systemic RAS mediators are associated with dysregulation of the microvasculature and with organ failure in clinical severe sepsis.

Methods

We studied 30 subjects with severe sepsis, and 10 healthy control subjects. Plasma was analyzed for plasma renin activity (PRA) and angiotensin II concentration (Ang II). Using near-infrared spectroscopy, we measured the rate of increase in the oxygen saturation of thenar microvascular hemoglobin after five minutes of induced forearm ischemia. In so doing, we assessed bulk microvascular hemoglobin influx to the tissue during reactive hyperemia. We studied all subjects 24 hours after the development of organ failure. We studied a subset of 12 subjects at an additional timepoint, eight hours after recognition of organ failure (early sepsis).

Results

After 24 hours of resuscitation to clinically-defined endpoints of preload and arterial pressure, Ang II and PRA were elevated in septic subjects and the degree of elevation correlated negatively with the rate of microvascular reoxygenation during reactive hyperemia. Early RAS mediators correlated with microvascular dysfunction. Early Ang II also correlated with the extent of organ failure realized during the first day of sepsis.

Conclusions

RAS is activated in clinical severe sepsis. Systemic RAS mediators correlate with measures of microvascular dysregulation and with organ failure.

Impaired myocardial blood flow reserve in subjects with metabolic syndrome analyzed using positron emission tomography and N-13 labeled ammonia

PURPOSE

Coronary vasomotor response might be impaired in metabolic syndrome (MS); however, the precise abnormality has not been elucidated. The aim of this study was to assess coronary-vasomotor response in MS subjects using N-13 labeled ammonia and positron emission tomography.

METHODS AND RESULTS

Myocardial blood flow (MBF) was measured at rest and during adenosine infusion in MS subjects (n = 13, MS group) with no definite evidence of heart disease and in subjects without MS (n = 14, non-MS group). Coronary vascular resistance (CVR) was calculated by dividing the mean aortic blood pressure by MBF. Myocardial blood flow reserve (MFR) was calculated as the ratio of the MBF during adenosine infusion to that during rest. Blood chemical parameters were measured to evaluate their relationship with MFR. During adenosine infusion, MBF was lower (p = 0.0085) and CVR higher (p = 0.0128) in the MS group than in the non-MS group and MFR was significantly lower in the MS group than in the non-MS group (2.13 +/- 0.99 vs. 3.38 +/- 0.95, p = 0.0027). Multivariate analysis demonstrated that the homeostasis model assessment-insulin resistance (p < 0.05) and the presence of hypertension (p < 0.05) were independent determinants of MFR.

CONCLUSIONS

The results indicate that MFR was impaired in MS subjects, suggesting that an abnormal coronary microvascular response occurred in these subjects. This abnormality may have been partially due to insulin resistance and hypertension.

Green tea catechins improve human forearm vascular function and have potent anti-inflammatory and anti-apoptotic effects in smokers

OBJECTIVE

Several epidemiological investigations have reported that green tea reduces cardiovascular and cerebral vascular risks. Green tea catechins may improve peripheral endothelial dysfunction in smokers. The purpose of this study was to elucidate the beneficial effect of green tea catechins on the repair of endothelial dysfunction in smokers.

METHODS

Thirty healthy male smokers divided into three groups ingested a green tea beverage containing 0 mg (control group), 80 mg (middle dose group) or 580 mg (high dose group) of green tea catechins (GTC) daily for two weeks, and endothelial-dependent vasodilatation was investigated by measuring forearm blood flow (FBF) response to reactive hyperemia (RH) by venous occlusion strain-gauge plethysmography.

RESULTS

An acute effect was that the FBF response to RH significantly increased 2 hr after GTC intake in the high dose group. However, no increase was observed in the other groups. The chronic administration of GTC for one or two weeks ameliorated the FBF responses to RH in the high dose group. On the other hand, no significant increase was observed in the FBF responses to RH in the other groups. Moreover, the plasma concentration of 8-OHdG, IL-6, TNF-alpha, and soluble Fas decreased significantly for two weeks in the high dose group, however, the level of IL-1 beta remained unchanged over this period.

CONCLUSION

Green tea consumption over short and long periods appears to ameliorate endothelial dysfunction by scavenging free radicals with anti-inflammatory and anti-apoptotic properties in healthy male smokers.

Effect of combined resistance and aerobic training on reactive hyperemia in men

Reduced response to reactive hyperemia (RH) in the extremities reflects impaired endothelium-dependent vasodilation of the microvasculature. The aims of the present study were to determine whether resistance training and a combination of aerobic and resistance training increase the endothelial vasodilation of the forearm assessed by RH. A total of 39 young men were assigned to either high-intensity resistance training (HIR; six types of exercises, 80% 1RM x 10 repetitions x 3 sets, n = 14) or moderate-intensity resistance training (MIR; six types of exercises, 50% 1RM x 16 repetitions x 3 sets, n = 14) or a combination of high-intensity resistance training and moderate-intensity endurance training (COMBO; HIR and 60% maximal heart rate x 30 min, n = 11) groups. We measured forearm blood flow response to RH before and after 4 months of exercise intervention. All training groups increased maximal strength in all muscle groups tested (all P < 0.05). After 4 months of training, the forearm blood flow during RH increased significantly in the MIR and COMBO groups, from 57 +/- 4 to 66 +/- 7 ml/min per 100 ml tissue and from 59 +/- 6 to 74 +/- 8 ml/min per 100 ml tissue, respectively (both P < 0.05). There was no change in the response to RH in the HIR groups. In conclusion, the findings in this study demonstrate that combined resistance and aerobic training may affect the vasoreactivity response to RH in the forearm, but not resistance training alone.

Clinical Assessment of Endothelial Function

The endothelium is crucial in the maintenance of normal vascular function and disturbance of this balance is a key early event in the development of vascular disease. A wide range of techniques currently exists for assessment of endothelial function in both the coronary and the peripheral vasculature. Many of these in vivo tests have concentrated on measuring nitric oxide bioavailability, however more recently methods for measuring other vascular parameters, such as tissue-plasminogen activator release, have been used. Furthermore indirect systemic measurements of endothelial function and endothelial progenitor cells have been investigated. These methods have given great insights into the pathophysiology of atherosclerosis and have aided in the development of a number of antiatherosclerotic therapies. Importantly the methods used to date for assessing endothelial function in vivo are accurate, reproducible and correlate with the future risk of cardiovascular events. The development of new techniques and the constant refinement of established techniques suggest that many more insights are to be gained from clinical assessment of endothelial function.

Endothelial dysfunction: from molecular mechanisms to measurement, clinical implications, and therapeutic opportunities

Endothelial dysfunction has been implicated as a key factor in the development of a wide range of cardiovascular diseases, but its definition and mechanisms vary greatly between different disease processes. This review combines evidence from cell-culture experiments, in vitro and in vivo animal models, and clinical studies to identify the variety of mechanisms involved in endothelial dysfunction in its broadest sense. Several prominent disease states, including hypertension, heart failure, and atherosclerosis, are used to illustrate the different manifestations of endothelial dysfunction and to establish its clinical implications in the context of the range of mechanisms involved in its development. The size of the literature relating to this subject precludes a comprehensive survey; this review aims to cover the key elements of endothelial dysfunction in cardiovascular disease and to highlight the importance of the process across many different conditions.

Acute effects of different alcoholic beverages on vascular endothelium, inflammatory markers and thrombosis fibrinolysis system

BACKGROUND & AIM

Mild alcohol consumption has been associated with decreased cardiovascular risk, although the underlying mechanisms are still unclear. We compared the acute effects of several alcoholic beverages on endothelial function, inflammatory process and thrombosis/fibrinolysis system in young adults.

METHODS

In this randomized intervention trial, healthy young individuals with no risk factor for atherosclerosis were randomized into 5 equally sized groups and received an equal amount of alcohol (30 g), as red wine (264 ml), white wine (264 ml), beer (633 ml), whisky (79 ml) or water (250 ml). Forearm blood flow was determined by gauge-strain plethysmography, at baseline, 1 and 4 h after alcohol intake. Levels of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-alpha), C-reactive protein (CRP), fibrinogen (Fib), plasminogen activator inhibitor (PAI-1), von Willebrand factor (vWF) and tissue plasminogen activator (tPA) were determined at baseline and 4 h after alcohol consumption.

RESULTS

Reactive hyperemia was significantly increased 1 h after beer and red wine consumption (p<0.05 for both), while it returned at baseline at 4 h (p=ns vs baseline) but remained unchanged in all the other groups. vWF was decreased in the beer and red wine groups (p<0.05 for both) only. PAI-1/tPA ratio remained unchanged only in red wine and control group. Inflammatory markers remained unchanged in all the groups.

CONCLUSIONS

Acute consumption of red wine or beer improves endothelial function and decreases vWF levels, suggesting that the type of beverage may differently affect endothelial function and thrombosis/fibrinolysis system in healthy adults.

Fixed combination of perindopril and indapamide at low dose improves endothelial function in essential hypertensive patients after acute administration

BACKGROUND

Fixed combination of angiotensin-converting enzyme inhibitors (ACEIs) with thiazide-type diuretics at low dose has been used as first-line therapy for the treatment of essential hypertension but their effect on conduit artery endothelial dysfunction remains unknown.

METHODS

Thirteen hypertensive patients were assessed after acute administration of a placebo, fixed combination of perindopril-indapamide at low dose: D1 (2 mg/0.625 mg) and twice this dose: D2 (4 mg/1.25 mg), during a double-blind, randomized, crossover study, and were compared with 13 matched controls. Mean arterial pressure (MAP), radial artery diameter (echotracking) and flow (Doppler) were measured during flow-mediated dilatation (FMD) induced by post-ischemic hyperemia (PIH). PIH was characterized by peak flow and duration of hyperemia (t(1/2)). Endothelium-independent dilatation was assessed by trinitrine.

RESULTS

In hypertensive patients compared with controls, basal radial artery diameter and flow, peak flow, and trinitrine responses were similar while MAP was increased (115 +/- 3 vs. 87 +/- 2 mm Hg), t(1/2) was decreased (11.1 +/- 1.9 vs. 17.2 +/- 2.2 s), and FMD was altered (radial diameter increase: 203 +/- 14 vs. 304 +/- 15 microm). Compared with placebo, only D2 decreased MAP (placebo: 115 +/- 3; D1: 112 +/- 4; D2: 103 +/- 4 mm Hg) and increased t(1/2) (placebo: 11.1 +/- 1.9; D1: 8.7 +/- 1.5; D2:13.0 +/- 1.9 s). Conversely, D1 and D2 increased FMD (placebo: 203 +/- 14; D1: 218 +/- 22; D2: 227 +/- 23 microm) with no change in basal diameter and flow, peak flow, and trinitrine responses.

CONCLUSION

These results demonstrate that a fixed combination of ACEI/diuretic at low dose significantly improves radial artery FMD in hypertensive patients and suggest a direct effect on conduit artery endothelium that may contribute to vascular protection.

Methionine-loading rapidly impairs endothelial function, by mechanisms independent of endothelin-1: evidence for an association of fasting total homocysteine with plasma endothelin-1 levels

OBJECTIVE

Homocysteinemia is associated with elevated oxidative stress and impaired endothelial function. In the present study we examined the impact of oxidative stress in the development of endothelial dysfunction in both chronic and acute (methionine-induced) homocysteinemia in humans. We also examined the role of endothelin-1 (ET-1) in the development of endothelial dysfunction in these two conditions.

METHODS

In this double-blind placebo controlled study, 28 subjects of both genders (14 with homocysteinemia and 14 healthy controls) underwent methionine-loading (100mg/Kg body weight) in a standard juice, containing vitamins C (2g) plus E (800IU) (n = 14) or no vitamins (placebo group, n = 14). Forearm vasodilatory response to reactive hyperemia, plasma total homocysteine (tHcy), oxidized LDL (ox-LDL), ET-1 and soluble vascular cell adhesion molecule (sVCAM-1), were evaluated at baseline and 4 hours post methionine loading (4hPML).

RESULTS

Chronic homocysteinemia was associated with increased oxLDL (p < 0.01), higher ET-1 (p < 0.05) and impaired endothelial function (p < 0.01). However, oxLDL (but not ET-1) was increased 4hPML in the placebo group, an effect prevented by antioxidant vitamins. The development of severe endothelial dysfunction 4hPML was not however prevented by antioxidants. In linear regression analysis, fasting tHcy was an independent predictor of baseline oxLDL (p = 0.0001), but not of ET-1 levels. On the contrary, oxLDL was the main predictor of ET-1 (p = 0.008), suggesting that tHcy may increase ET-1 by enhancing the production of oxLDL.

CONCLUSIONS

Both chronic and acute methionine-induced homocysteinemia are associated with elevated oxidative stress status. Although ET-1 is increased in chronic homocysteinemia, it does not participate in the rapid development of endothelial dysfunction after methionine loading. These findings suggest that despite its potential role in chronic homocysteinemia, ET-1 has a limited contribution to the development of endothelial dysfunction in acute, methionine-induced homocysteinemia in humans.

Endothelial dysfunction and oxidant status in pediatric patients with hemoglobin E-beta thalassemia

Thalassemia major is characterized by anemia, iron overload, and oxidant damage to major organs, especially the cardiovascular system. Oxidative stress is ultimately involved in endothelial dysfunction, a condition which is evident in adults suffering from various cardiovascular diseases including thalassemia. We investigated endothelial function in pediatric patients with hemoglobin E-beta thalassemia (HbE-beta thalassemia), who have been exposed to excessive iron and oxidative stress for much shorter period than adults with thalassemia. We recruited 22 blood transfusion-dependent HbE-beta thalassemia patients aged 11.8 +/- 2.9 years and 20 healthy controls aged 12.1 +/- 1.7 years. Oxidant status was determined, and endothelial function was assessed by a forearm blood flow technique. Oxidative stress was increased in the thalassemic patients, as blood glutathione (GSH) and ratios of reduced GSH to GSH disulfide were markedly reduced, and superoxide anion released from blood cells was highly elevated. Oxidative stress response, assessed by gamma-glutamylcysteine ligase activity, was increased approximately twofold in thalassemia patients. Basal forearm blood flow was significantly increased in patients compared with controls (7.3 +/- 1.8 vs 6.0 +/- 1.8 ml/100 ml tissue/min, respectively), whereas forearm vasodilatory response to reactive hyperemia was depressed by 50% in patients compared with controls. Endothelial function is impaired in young thalassemia patients, and impaired endothelial function is associated with oxidant stress.

Discrepancy between improvement of insulin sensitivity and that of arterial endothelial function in patients receiving antihypertensive medication

OBJECTIVES

We evaluated whether the changes in the insulin sensitivity observed in hypertensive patients following treatment with an angiotensin II receptor blocker (candesartan) or calcium-channel antagonist (amlodipine) might be related to improvement of the endothelial function (END) and/or plasma level of high-sensitive C-reactive protein (CRP) following such treatment.

METHODS AND RESULTS

Seventy-one hypertensive patients (age: 58 +/- 10 years) without obvious target organ damage were allocated randomly to treatment with either candesartan at the dose of 8 mg/day or amlodipine at the dose of 5 mg/day. At the start and end of the 8-month treatment period, the homeostasis model assessment index of insulin resistance (HOMA-IR index), plasma CRP and END, as assessed by changes in the forearm blood flow in reactive hyperemia, were determined. While significant improvement of END was observed in patients receiving either drug, only candesartan, but not amlodipine, also reduced the plasma CRP and HOMA-IR index (2.13 +/- 1.92 --> 1.53 +/- 1.47, P < 0.05). In the patients receiving treatment with candesartan, stepwise multivariate linear regression analysis revealed that the percent change in the HOMA-IR index was significantly and independently correlated with that in the plasma CRP (beta = 0.38, P < 0.05), but not with that in END:

CONCLUSION

Improvement of the END alone by the antihypertensive medication might not entirely explain the improvement of the insulin sensitivity observed in these patients. Additional mechanisms may be involved, and the anti-inflammatory effects of the medication observed in patients treated with candesartan may also be related, at least in part, to the observed improvement of insulin sensitivity.

Interaction of endothelial nitric oxide and angiotensin in the circulation

Discovery of the unexpected intercellular messenger and transmitter nitric oxide (NO) was the highlight of highly competitive investigations to identify the nature of endothelium-derived relaxing factor. This labile, gaseous molecule plays obligatory roles as one of the most promising physiological regulators in cardiovascular function. Its biological effects include vasodilatation, increased regional blood perfusion, lowering of systemic blood pressure, and antithrombosis and anti-atherosclerosis effects, which counteract the vascular actions of endogenous angiotensin (ANG) II. Interactions of these vasodilator and vasoconstrictor substances in the circulation have been a topic that has drawn the special interest of both cardiovascular researchers and clinicians. Therapeutic agents that inhibit the synthesis and action of ANG II are widely accepted to be essential in treating circulatory and metabolic dysfunctions, including hypertension and diabetes mellitus, and increased availability of NO is one of the most important pharmacological mechanisms underlying their beneficial actions. ANG II provokes vascular actions through various receptor subtypes (AT1, AT2, and AT4), which are differently involved in NO synthesis and actions. ANG II and its derivatives, ANG III, ANG IV, and ANG-(1-7), alter vascular contractility with different mechanisms of action in relation to NO. This review article summarizes information concerning advances in research on interactions between NO and ANG in reference to ANG receptor subtypes, radical oxygen species, particularly superoxide anions, ANG-converting enzyme inhibitors, and ANG receptor blockers in patients with cardiovascular disease, healthy individuals, and experimental animals. Interactions of ANG and endothelium-derived relaxing factor other than NO, such as prostaglandin I2 and endothelium-derived hyperpolarizing factor, are also described.

Imidapril

Imidapril (Tanatril), through its active metabolite imidaprilat, acts as an ACE inhibitor to suppress the conversion of angiotensin I to angiotensin II and thereby reduce total peripheral resistance and systemic blood pressure (BP). In clinical trials, oral imidapril was an effective antihypertensive agent in the treatment of mild to moderate essential hypertension. Some evidence suggests that imidapril also improves exercise capacity in patients with chronic heart failure (CHF) and reduces urinary albumin excretion rate in patients with type 1 diabetes mellitus. Imidapril was well tolerated, with a lower incidence of dry cough than enalapril or benazepril, and is a first choice ACE inhibitor for the treatment of mild to moderate essential hypertension.

Asymmetrical dimethylarginine regulates endothelial function in methionine-induced but not in chronic homocystinemia in humans: effect of oxidative stress and proinflammatory cytokines

BACKGROUND

Homocystinemia is a metabolic abnormality associated with endothelial dysfunction and increased cardiovascular disease risk. The underlying mechanisms of these effects, however, are obscure.

OBJECTIVE

We examined the effect of asymmetrical dimethylarginine (ADMA) on endothelial dysfunction in methionine-induced and chronic homocystinemia and evaluated the regulatory role of oxidative stress and proinflammatory cytokines on the release of ADMA.

DESIGN

In this double-blind, placebo-controlled parallel group study, 30 subjects of both sexes (15 with homocystinemia and 15 healthy controls) underwent methionine loading, with simultaneous administration of a combination of vitamin C (2 g) plus alpha-tocopherol (800 IU) or placebo. Endothelial function in forearm resistance vessels and concentrations of ADMA, oxidized LDL, and proinflammatory cytokines were determined at baseline and 4 h after methionine loading.

RESULTS

Both chronic and methionine-induced homocystinemia were associated with increased oxidized LDL (P < 0.01), higher expression of the proinflammatory cytokine interleukin 6 (P < 0.05), and endothelial dysfunction (P < 0.01). Although ADMA rapidly increased in acute homocystinemia (P < 0.01) and was correlated with forearm hyperemic response at 4 h after methionine loading (r = -0.722, P = 0.0001), it was not higher in subjects with high versus low fasting homocysteine. High-dose antioxidant treatment prevented methionine-induced elevation of oxidized LDL and interleukin 6 but failed to prevent the increase in ADMA or endothelial dysfunction.

CONCLUSIONS

Both chronic and methionine-induced homocystinemia are characterized by increased oxidative stress and proinflammatory cytokines, which may contribute to the development of endothelial dysfunction. However, the ADMA pathway is activated only in acute homocystinemia by mechanisms not mediated by oxidized LDL or proinflammatory stimuli.

Pharmacotherapies and their influence on asymmetric dimethylargine (ADMA)

Elevated plasma concentrations of the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA) are found in various clinical settings, including renal failure, coronary heart disease, hypertension, diabetes and pre-eclampsia. In healthy people acute infusion of ADMA promotes vascular dysfunction, and in mice chronic infusion of ADMA promotes progression of atherosclerosis. Thus, ADMA may not only be a marker but also an active player in cardiovascular disease, which makes it a potential target for therapeutic interventions. This review provides a summary and critical discussion of the presently available data concerning the effects on plasma ADMA levels of cardiovascular drugs, hypoglycemic agents, hormone replacement therapy, antioxidants, and vitamin supplementation. We assess the evidence that the beneficial effects of drug therapies on vascular function can be attributed to modification of ADMA levels. To develop more specific ADMA-lowering therapies, mechanisms leading to elevation of plasma ADMA concentrations in cardiovascular disease need to be better understood. ADMA is formed endogenously by degradation of proteins containing arginine residues that have been methylated by S-adenosylmethionine-dependent methyltransferases (PRMTs). There are two major routes of elimination: renal excretion and enzymatic degradation by the dimethylarginine dimethylaminohydrolases (DDAH-1 and -2). Oxidative stress causing upregulation of PRMT expression and/or attenuation of DDAH activity has been suggested as a mechanism and possible drug target in clinical conditions associated with elevation of ADMA. As impairment of DDAH activity or capacity is associated with substantial increases in plasma ADMA concentrations, DDAH is likely to emerge as a prime target for specific therapeutic interventions.

Genetic polymorphisms G894T on the eNOS gene is associated with endothelial function and vWF levels in premature myocardial infarction survivors

BACKGROUND

Genetic polymorphism G894T on endothelial nitric oxide synthase (eNOS) gene has been associated with endothelial dysfunction in young smokers, but its role in the pathogenesis of MI is obscure. We examined the effect of G894T polymorphism on endothelial function, on markers of endothelial cells injury and activation such as von Willebrand factor (vWF) and on serum levels of proinflammatory cytokines such as interleukins 6 (IL-6) and 1b (IL-1b), in young myocardial infarction (MI) survivors.

METHODS

The study population consisted of 56 patients with a history of premature MI. The forearm blood flow (FBF) was measured by using strain-gauge plethysmography during reactive hyperemia and after sublingual administration of nitroglycerin. G894T polymorphism was determined by polymerase chain reaction (PCR), while plasma vWF and serum IL1b and IL-6 levels were determined with ELISA.

RESULTS

There was no significant difference in resting FBF and in the responses to nitroglycerin between the genotypes. However, the presence of T allele (GT+TT, n=35) was associated with decreased FBF during reactive hyperemia (10.23+/-0.70 ml/100ml tissue/min) and decreased forearm vasodilatory response to reactive hyperemia (54.28+/-4.81%) compared to GG (13.82+/-0.92 ml/100 ml tissue/min and 83.92+/-9.89% respectively, p<0.01 for both). Carriers of the T allele had also higher levels of vWF (79.66+/-5.56%) compared to GG (60.94+/-5.27% p<0.05). However, no significant difference was observed in IL-1b and IL-6 serum levels between the genotypes (p=ns for both).

CONCLUSIONS

The presence of 894T allele on eNOS gene is associated with impaired endothelial function and higher levels of von Willebrand factor in relatively young patients with myocardial infarction. This finding implies that genetic polymorphism G894T on eNOS may affect endothelial function in patients with a history of premature myocardial infarction.

Optimal Vascular Protection: A Case for Combination Antihypertensive Therapy

Endothelial dysfunction is an important factor in the pathogenesis of atherosclerosis, hypertension, and heart failure. The endothelium mediates vascular tone, structure, and function by the release and regulation of multiple vasoactive substances that promote or inhibit vasodilation, vasoconstriction, cell growth, and other mechanisms. The effect of antihypertensive drugs on endothelial function may be an important indicator of their ability to reduce risks for cardiovascular morbidity and mortality. Endothelium-dependent vasodilation induced by various antihypertensive drugs is accurately measured with high-resolution ultrasound of flow-mediated dilation of the brachial artery. Calcium channel blockers and angiotensin-converting enzyme inhibitors have been shown to reverse endothelial dysfunction. The benefits of angiotensin-converting enzyme inhibitors and calcium channel blockers on the endothelium are believed to derive from their effects on nitric oxide production and antioxidant effects, possibly independent of blood pressure reduction. Due to their complementary mechanisms of action, it has been hypothesized that the combination of an angiotensin-converting enzyme inhibitor and a calcium channel blocker will provide superior cardiovascular protection, in part by producing an additive effect of increased nitric oxide availability, when compared with either agent alone.

Renal and Vascular Protective Effects of Telmisartan in Patients with Essential Hypertension

It is known that the angiotensin receptor blockers (ARBs) have organ protective effects in patients with heart failure or renal impairment. Several studies have revealed that the ARB telmisartan has an organ protective effect, but there have been few studies directly comparing the effects of telmisartan and calcium antagonists, since most clinical studies on telmisartan have been conducted in treated patients or patients on combination therapy. The present study was conducted to compare the renal and vascular protective effects of telmisartan monotherapy and calcium antagonist monotherapy in untreated hypertensive patients. Forty-three patients with untreated essential hypertension were randomized to receive amlodipine (n=22) or telmisartan (n=21), which were respectively administered at doses of 5 mg and 40 mg once daily in the morning for 24 weeks. The patients were examined before and after treatment to assess changes of renal function, flow-mediated dilation (a parameter of vascular endothelial function), and brachial-ankle pulse wave velocity (baPWV; a parameter of arteriosclerosis). Before treatment, there were no significant differences in these parameters between groups. The decreases of urinary albumin excretion and baPWV, and the increase of flow-mediated dilation were significantly greater in the telmisartan group than the amlodipine group, while the antihypertensive effects were not significantly different between the two groups. In conclusion, these results suggest that telmisartan is more effective at protecting renal function and vascular endothelial function, and at improving arteriosclerosis than the calcium channel blocker in patients with essential hypertension.

Effects of combined administration of low dose atorvastatin and vitamin E on inflammatory markers and endothelial function in patients with heart failure

BACKGROUND

Heart failure has been associated with impaired endothelial function, increased inflammatory process and elevated oxidative stress status. Both statins and vitamin E separately improve endothelial function in patients with hypercholesterolemia and/or advanced atherosclerosis.

AIM

To evaluate the effect of atorvastatin alone or in combination with vitamin E on endothelial function and serum levels of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-alpha) and vascular cells adhesion molecule (sVCAM-1) in patients with ischemic heart failure.

METHODS

Thirty-eight male patients with ischemic cardiomyopathy were randomly divided into three groups and received either atorvastatin 10 mg/day (n = 14), a combination of atorvastatin 10 mg/day plus vitamin E 400 IU/day (n = 12), or no statin or antioxidant treatment (n=12, controls) for 4 weeks. Forearm blood flow (FBF) was measured using venous occlusion strain-gauge plethysmography. Forearm vasodilatory response to reactive hyperemia (RH%) or to nitrate (NTG%) was defined as the percent change of FBF from rest to the maximum flow during reactive hyperemia or after nitrate administration, respectively.

RESULTS

RH% was significantly improved in both the atorvastatin-treated (p < 0.01) and atorvastatin plus vitamin E groups (p < 0.05), but the increase was significantly higher in the atorvastatin-treated group (p < 0.05). Serum levels of IL-6, TNF-alpha and sVCAM-1 were decreased in the atorvastatin-treated group (p < 0.05 for all), but remained unaffected in the other two groups (p = NS for all).

CONCLUSIONS

Low dose atorvastatin treatment improves endothelial function and reduces the expression of proinflammatory cytokines and adhesion molecules in patients with ischemic heart failure, an effect partly depressed by vitamin E.

A novel endothelial function test using Doppler flow: the snuff-box technique

Precise measurement of Doppler estimated blood flow volume using the standard technique of flow-mediated vasodilation is not possible because the anatomic course of the brachial or radial artery goes against the principle of Doppler measurements that the insonation angle should be less than 30 degrees . The radial artery in the anatomic snuff-box area is useful for the measurement of Doppler signals as the insonation angle is less than 30 degrees and because the size of the artery allows observation of laminar flow. We introduce the snuff-box technique as a novel endothelial function test that enables measurement of both blood flow and diameter of the radial artery. Changes in diameter and blood flow volume during reactive hyperemia were examined in 15 healthy volunteers. Changes in blood flow determined using the snuff-box technique were compared with changes in forearm blood flow determined by plethysmography. The diameter of the radial artery increased from 2.3 +/- 0.2 mm at baseline to 2.8 +/- 0.4 mm at 60 s after deflation (P = 0.0017), and blood flow increased from 52.3 +/- 21.4 ml/min at baseline to 108.6 +/- 33.1 ml/min at 15 s after deflation (P = 0.0014). Percentile blood flow determined by the snuff-box technique correlated significantly with that determined by plethysmography (r = 0.824, P = 0.0002). Both blood flow volume and artery diameter can be measured with high reliability using the snuff-box technique, as has been shown in subjects with reactive hyperemia.

Evidence of vascular dysfunction in young patients with successfully repaired coarctation of aorta

It is well documented that in patients with coarctation of the aorta life expectancy is not normal even after successful coarctation repair (SCR), primarily due to cardiovascular events. We examined endothelial function in the forearm circulation, the mechanical properties and intima/media thickness in carotid and femoral arteries and the inflammatory process in normotensive patients, after coarctation repair. Fifteen patients, 29+/-2 years old, 12+/-2.9 years after SCR and 16 age- and sex-matched controls were enrolled in our study. Forearm blood flow was determined by gauge-strain plethysmography. Forearm vasodilatory response to reactive hyperemia was expressed as the %change from baseline to post-reactive hyperemia blood flow. High resolution ultrasound was used for determination of intima/media thickness and elastic properties of carotid and femoral arteries. Serum levels of soluble vascular adhesion molecule 1 (sVCAM-1), intercellular adhesion molecule 1 (sICAM-1), E-selectin, and interleukines 1b (IL-1b) and 6 (IL-6) were determined by ELISA. Reactive hyperemia was significantly decreased in patients compared to controls (p<0.01). Patients with SCR had higher intima/media thickness and decreased distensibility in the carotid arteries than controls (p<0.01 for both). Serum levels of sICAM-1, sSVCAM-1, E-selectin and IL-1b were higher in SCR group than in controls (p<0.05 for all). Adult patients after SCR have impaired endothelial function in the forearm circulation, increased intima/media thickness, decreased distensibility in the carotid arteries and increased levels of proinflammatory cytokines and adhesion molecules than healthy controls. These results may partly explain the high incidence of coronary artery disease in patients with repaired coarctation of the aorta.

Effects of atorvastatin on reactive hyperemia and inflammatory process in patients with congestive heart failure

Purpose of the study was to investigate whether short-term atorvastatin treatment improves endothelial function and affects inflammatory process in patients with heart failure (HF) and normal cholesterol levels. HF is characterized by endothelial dysfunction and increased inflammatory process, while statins restore endothelial function having also anti-inflammatory effects in hypercholesterolemic patients. We investigated the effect of 4-week atorvastatin treatment (10 mg/day) on endothelial function and inflammatory markers in patients with HF and cholesterol levels <220 mg/dl. Patients were randomly allocated into groups and received atorvastatin (n=19) or no statin (n=19). Forearm blood flow was measured using gauge-strain plethysmography. Serum levels of tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6), and soluble vascular cell adhesion molecule (sVCAM-1) were determined with ELISA. Data are expressed as median [25th-75th percentile]. Forearm vasodilatory response to reactive hyperemia was significantly improved in atorvastatin-treated patients (from 38.1% [32.0-59.1] to 70.0% [61.1-106.3], P<0.01), while it remained unaffected in the control group. Levels of IL-6, TNF-alpha and sVCAM-1 were decreased in atorvastatin-treated group (from 7.8 pg/ml [4.8-9.5], 3.2 pg/ml [2.7-4.8] and 595 ng/ml [440-810] to 5.6 pg/ml [2.5-9.0], 2.8 pg/ml [2.0-3.6] and 289 ng/ml [169-368], respectively, P<0.05 for all) but not in the control group. These findings indicate that atorvastatin may improve forearm vasodilatory response to reactive hyperemia and depress inflammatory process in patients with heart failure and normal baseline cholesterol levels.

Forearm endothelial function and bone mineral loss in postmenopausal women

It is widely believed that the vasculature plays an important role in bone remodeling. We investigated the relationship between forearm endothelial function and bone mass in the lumbar spine in early postmenopausal women without a history of smoking or diabetes mellitus. We studied the forearm resistance artery endothelial function in 110 Japanese women-52 postmenopausal women with normal spinal bone mineral density (BMD), 36 postmenopausal women with osteopenia, and 22 osteoporotic postmenopausal women. Forearm blood flow (FBF) during reactive hyperemia and after sublingual nitroglycerin (NTG) administration was measured by strain-gauge plethysmography. BMD of the lumbar spine (L2-L4) was measured by dual-energy X-ray absorptiometry. After adjustment for age, body mass index, years since the start of menopause, and basal FBF, women with osteoporosis had a lower maximal FBF response to reactive hyperemia (28.4 +/- 3.8 mL/min per 100 mL tissue) than those with normal BMD (39.8 +/- 2.8 mL/min per 100mL tissue) or osteopenia (35.6 +/- 2.5 mL/min per 100mL tissue) (P = 0.029). A significant increase in serum angiotensin-converting enzyme (ACE) activity (P = 0.042) and a significant decrease in the serum concentrations of nitrite/nitrate (P = 0.041) were noted in osteoporotic women compared to women with normal BMD or osteopenia. The present findings suggest that postmenopausal women with low BMD, especially those with osteoporosis, have impaired endothelial function in the forearm resistance arteries.

Combined effects of smoking and hypercholesterolemia on inflammatory process, thrombosis/fibrinolysis system, and forearm hyperemic response

The combined effects of smoking and hypercholesterolemia on the inflammatory process, the thrombosis/fibrinolysis system, and forearm hyperemic response were investigated. It was shown that smokers with hypercholesterolemia (n = 25) had a reduced and delayed forearm hyperemic response compared with healthy smokers (n = 24), patients with hypercholesterolemia (n = 26), and healthy controls (n = 75; p <0.01 for all). This phenomenon was associated with a respective increase in the inflammatory process and changes in the thrombosis/fibrinolysis system.

Effect of amlodipine and cilazapril treatment on platelet Ca2+ handling in spontaneously hypertensive rats

Abnormal Ca2+ handling and enhanced aggregation response have been reported in platelets from spontaneously hypertensive rats (SHR) and patients with essential hypertension, and thought to be involved in the progression of target organ damage of hypertension. It is important to examine whether antihypertensive therapy can improve the abnormal platelet response in hypertension. We investigated the effect of antihypertensive treatment such as amlodipine and cilazapril on Ca2+ handling and aggregation response in SHR platelets. Four-week-old male SHR were divided into three groups. Each group was treated with amiodipine (A: 10 mg/kg/day), cilazapril (C: 10 mg/kg/day) or vehicle (V) for 8 weeks by gavage. At 12-week-old, platelet [Ca2+]i was measured with fura-2 in each group of SHR and age-matched Wistar-Kyoto rats (WKY) as normal control. Systolic blood pressure in amlodipine and cilazapril treated groups were similar with WKY and significantly lower than vehicle treated group (A: 124 +/- 9, C: 126 +/- 9, WKY: 122 +/- 10 and V: 180 +/- 9 mmHg, respectively). The basal [Ca2+]i in the three groups of SHR were similar and higher than WKY (A: 47 +/- 1.7, C: 47 +/- 1.2, V: 48 +/- 3.9 and WKY: 40 +/- 4.0 nmol/l, respectively). There were no significant differences in thrombin (0.1 U/ml)-stimulated [Ca2+]i rise in the presence or absence of extracellular Ca2+ among the three groups of SHR and these were higher than WKY. Intracellular Ca2+ discharge capacity, assessed by the ionomycinstimulation was similar in the all groups. Thrombin-induced maximum platelet aggregation responses in the three groups of SHR were similar and higher than WKY. The antihypertensive treatment of Ca2+ antagonist or ACE inhibitor gave no change in intraplatelet Ca2+ metabolism in SHR. These results support the hypothesis that an abnormal Ca2+ handling in SHR platelet is genetically determined and not improved by hypotensive therapy.

Endothelial function and proinflammatory cytokines in patients with ischemic heart disease and dilated cardiomyopathy

BACKGROUND

Proinflammatory cytokines such as tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6) are important mediators of immune response, associated with endothelial dysfunction in patients with coronary artery disease (CAD) or heart failure. We compared endothelial function and levels of IL-6 and TNF-alpha between patients with ischemic heart failure, dilated cardiomyopathy, CAD and healthy controls.

METHODS

The population consisted of 20 patients with dilated cardiomyopathy, 48 patients with ischemic cardiomyopathy, 26 patients with CAD and normal left ventricle function and 14 healthy controls. Forearm blood flow was measured using venous occlusion strain gauge plethysmography. Forearm vasodilatory response to reactive hyperemia (RH%) or to nitrate were considered as indexes of endothelium-dependent and endothelium-independent dilation, respectively.

RESULTS

Levels of IL-6 were significantly higher in ischemic cardiomyopathy compared to CAD patients (P<0.05) or controls (P<0.05) and in patients with dilated cardiomyopathy compared to controls (P<0.05). TNF-alpha levels were significantly higher in both groups with ischemic or dilated cardiomyopathy compared to CAD (P<0.05) or controls (P<0.05). RH% was significantly lower in ischemic and dilated cardiomyopathy compared to CAD (P<0.05) or controls (P<0.001) and higher in dilated than ischemic cardiomyopathy (P<0.05).

CONCLUSIONS

Impaired endothelial function and increased inflammatory process were found in both types of heart failure. A greater endothelial dysfunction was observed in patients with ischemic heart failure compared to those with dilated cardiomyopathy, implying that the underlying atherosclerosis may participate in this process.

Amlodipine improves vascular function in patients with moderate to severe hypertension

The long-term effects of amlodipine, a calcium channel blocker, were examined in patients with moderate to severe hypertension. Eighteen never-treated patients with moderate to severe essential hypertension (49 +/- 8 years) were studied. In all patients, forearm blood flow (FBF) was measured by plethysmography before and 6 months after amlodipine treatment. Endothelium-nondependent and endothelium-dependent vasodilations were assessed by intrabrachial infusion of sodium nitroprusside (SNP) and acetylcholine (ACh), respectively. FBF modification by vitamin C, an oxygen radical scavenger, was also assessed under ACh infusion. The results were compared with those of 13 normal subjects. Blood pressure was significantly lowered (from 176 +/- 17/97 +/- 13 to 144 +/- 12/82 +/- 10 mm Hg) after treatment (P < 0.01). Forearm vascular resistance was increased in the hypertensive patients before treatment; however, it was normalized after treatment during SNP infusion and was improved during ACh infusion. Since vitamin C improved FBF under ACh infusion both before and after the amlodipine treatment, it is suggested that the production of free radicals was not canceled by amlodipine. The analysis of heart rate variability showed that amlodipine does not activate sympathetic nerve function. Therefore, amlodipine is effective in lowering blood pressure associated with the improvement of vascular function, and is suggested to be an effective antihypertensive agent for patients with moderate to severe hypertension.

Comparison of forearm endothelial function between premenopausal and postmenopausal women with or without hypercholesterolemia

We sought to determine whether menopausal status or postmenopausal hypercholesterolemia affects forearm resistance artery endothelial function. We studied the forearm resistance artery endothelial function in 75 Japanese women: 25 premenopausal volunteers, 25 postmenopausal women with normal serum low-density lipoprotein (LDL) cholesterol concentrations, and 25 hypercholesterolemic postmenopausal women. Excluded from the study were patients with hypertriglyceridemia, hypertension, or diabetes, cigarette smokers. The forearm blood flow (FBF) during reactive hyperemia and after sublingual nitroglycerin (NTG) administration was measured by strain-gauge plethysmography. The serum concentrations of lipoprotein (a) [Lp(a)] were significantly higher in the hypercholesterolemic postmenopausal group than in the other two groups (P<0.01). These lipid parameters were similar between the premenopausal and postmenopausal women with normal cholesterol. The FBF responses to reactive hyperemia were significantly lower in the postmenopausal hypercholesterolemic women than in the other two groups (P<0.01). The reactive hyperemia also was impaired in the postmenopausal group with normal cholesterol as compared with the premenopausal group (P<0.01). Increases in FBF after NTG were similar between the three groups. By stepwise multivariate analysis, menopausal status and serum LDL cholesterol was the significant predictor of forearm endothelial function. These findings suggest that reactive hyperemia is impaired in forearm resistance arteries after menopause, especially in postmenopausal women with hypercholesterolemia.