Converting enzyme inhibitor improves forearm reactive hyperemia in essential hypertension

Effects of olmesartan and amlodipine on blood pressure, endothelial function, and vascular inflammation

BACKGROUND

Anti-hypertensive drugs can improve vascular endothelial function. However, the mechanism remains to be elucidated.

OBJECTIVES

This study sought to investigate mechanisms of anti-hypertensive drugs on improvement of vascular endothelial function in patients with essential hypertension.

METHODS

Forty-five patients (mean age 58.5 ± 11.2 years) with uncontrolled essential hypertension were randomly assigned to receive olmesartan, an angiotensin II type 1 receptor blocker (ARB) (N = 23), or amlodipine, a calcium channel blocker (CCB) (N = 22), for 6 months. Endothelial function was evaluated by flow-mediated dilatation (FMD) of the brachial artery. Vascular inflammation was measured by blood-normalized standardized uptake value, known as a target-to-background ratio (TBR) within the carotid arteries using 18F-fluorodeoxyglucose-positron emission tomography combined with computed tomography.

RESULTS

There were no significant differences of baseline clinical data between the ARB and CCB groups. Both anti-hypertensive drugs comparably lowered blood pressure and increased %FMD. TBR values were reduced by olmesartan (P < .001), while blood pressure variability was decreased by amlodipine (P = .004). Changes in %FMD from baseline (Δ%FMD) were inversely associated with ΔTBR in the olmesartan group (r = - .606, P = .003) and with Δsystolic blood pressure variability in the amlodipine group (r = - .434, P = .039).

CONCLUSION

Our study indicated that olmesartan and amlodipine could improve endothelial function in patients with essential hypertension in different manners, suppression of vascular inflammation, and decrease in blood pressure variability, respectively.

Cardiovascular risk in patients receiving antihypertensive drug treatment from the perspective of endothelial function

Blood-pressure-lowering therapy with antihypertensive drugs can reduce the risk of cardiovascular morbidity and mortality in patients with hypertension. However, patients treated with antihypertensive drugs generally have a worse prognosis than untreated individuals. Consistent with the results obtained from epidemiological studies, a clinical study showed that endothelial function was impaired more in treated patients with hypertension than in untreated individuals with the same blood pressure level, suggesting that blood-pressure-lowering therapy with currently available antihypertensive drugs cannot restore endothelial function to the level of that in untreated individuals. Several mechanisms of endothelial dysfunction in treated patients are postulated: irreversible damage to the endothelium caused by higher cumulative elevated blood pressure exposure over time; the persistence of the primary causes of hypertension even after the initiation of antihypertensive drug treatment, including an activated renin-angiotensin-aldosterone system, oxidative stress, and inflammation; and higher global cardiovascular risk related not only to conventional cardiovascular risk factors but also to undetectable nonconventional risk factors. Lifestyle modifications/nonpharmacological interventions should be strongly recommended for both untreated and treated individuals with hypertension. Lifestyle modifications/nonpharmacological interventions may directly correct the primary causes of hypertension, which can improve endothelial function and consequently reduce cardiovascular risk regardless of the use or nonuse of antihypertensive drugs.

Comparative Efficacy of Antihypertensive Agents in Flow-Mediated Vasodilation of Patients with Hypertension: Network Meta-Analysis of Randomized Controlled Trial

Hypertension induces both structural and functional changes in blood vessels, thereby increasing endothelial dysfunction, which in turn, contributes to an increase in blood pressure. A popular and widely used noninvasive tool, flow-mediated dilation (FMD), is used to examine peripheral artery endothelium-dependent dilation. This study aimed to compare the efficacies of different classes of antihypertensive agents based on their effects on FMD. PubMed, Embase, and Cochrane Library were queried till November 1, 2020. Comparative studies on the efficacies of two or more antihypertensive agents or placebos for hypertensive patients were included. The outcomes were variations in mean systolic and diastolic blood pressure. Two reviewers independently reviewed and filtered the literature and extracted the data; the Cochrane “risk of bias” method was used to evaluate the methodological quality of the randomized controlled trials. A network meta-analysis was performed using Stata 15.0 software with a total of 49 studies. Subgroup analysis based on age and duration of treatments was performed. As compared to the placebo group, patients receiving the antihypertensive drugs exhibited significantly enhanced FMD (ARB + CCB: 4.01%, 95% CI, 0.92–7.11%, p < 0.001; ACEI + ARB: 2.81%, 95% CI, 1.19–4.43%, p < 0.001; ACEI: 2.55%, 95% CI, 1.34–3.77%, p < 0.001; ARB: 2.22%, 95% CI, 1.05–3.38%, p < 0.001; β-blocker: 2.23%, 95% CI, 0.93–3.52%, p < 0.001). In the SUCRA curve for network meta-analysis, the combination of CCB and ARB was found to be the most effective in increasing FMD (SUCRA = 89.0%), followed by ACEI monotherapy (SUCRA = 74.2%). ARB combined with CCB was superior in improving the endothelial function measured as the FMD; ACEI monotherapy was the most effective treatment among the antihypertension medications. There were no significant differences between antihypertensive drug-based monotherapies.

Comparative study of microvascular function: Forearm blood flow versus dynamic retinal vessel analysis

OBJECTIVE

Recently, dynamic retinal vessel analysis (DVA) has gained interest for investigation of microvascular function but comparative measurements with standard methods like the forearm blood flow technique (FBF) are uncommon till now.

METHODS

We recruited 23 high-risk cardiovascular patients (Risk) and 17 healthy persons (Ctrl). During the FBF experiment, postocclusive reactive hyperaemia (RH) as well as endothelium-dependent and independent vasodilation was measured by infusion of acetylcholine (ACh) and sodium nitroprusside (SNP) into the brachial artery. The dynamic vessel analyzer was applied for measurement of the retinal arterial and venous response to flickering light during DVA and for determination of the central retinal arterial (CRAE) and venous equivalent (CRVE).

RESULTS

Forearm blood flow technique was significantly attenuated in the patient group during postocclusive RH (p < .005). The increase of FBF in response to SNP did not differ significantly between the two groups (p = .09). In contrast, the FBF response to ACh was significantly blunted in the patient group (p < .05), indicating endothelial dysfunction. DVA did not detect any difference of retinal arterial (p = .68) or retinal venous (p = .93) vasodilation between both groups. The CRAE (p = .55) and CRVE (p = .83) did not differ significantly in either group.

CONCLUSIONS

Forearm blood flow and DVA cannot be regarded as equivalent methods for testing of microvascular function. Possible explanations include differences in the vascular beds and vessel diameters examined as well as differences in the trigger mechanisms applied. Further studies are needed to define the role of DVA in this context.

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.

Effect of aldosterone-producing adenoma on endothelial function and Rho-associated kinase activity in patients with primary aldosteronism

The purpose of this study was to evaluate vascular function and activity of Rho-associated kinases (ROCKs) in patients with primary aldosteronism. Vascular function, including flow-mediated vasodilation (FMD) and nitroglycerine-induced vasodilation, and ROCK activity in peripheral leukocytes were evaluated in 21 patients with aldosterone-producing adenoma (APA), 23 patients with idiopathic hyperaldosteronism (IHA), and 40 age-, sex-, and blood pressure-matched patients with essential hypertension (EHT). FMD was significantly lower in the APA group than in the IHA and EHT groups (3.2±2.0% versus 4.6±2.3% and 4.4±2.2%; P<0.05, respectively), whereas there was no significant difference in FMD between the IHA and EHT groups. There was no significant difference in nitroglycerine-induced vasodilation in the 3 groups. ROCK activity was higher in the APA group than in the IHA and EHT groups (1.29±0.57 versus 1.00±0.46 and 0.81±0.36l; P<0.05, respectively), whereas there was no significant difference in ROCK activity between the IHA and EHT groups. FMD correlated with age (r=-0.31; P<0.01), plasma aldosterone concentration (r=-0.35; P<0.01), and aldosterone:renin ratio (r=-0.34; P<0.01). ROCK activity correlated with age (r=-0.24; P=0.04), plasma aldosterone concentration (r=0.33; P<0.01), and aldosterone:renin ratio (r=0.46; P<0.01). After adrenalectomy, FMD and ROCK activity were restored in patients with APA. APA was associated with both endothelial dysfunction and increased ROCK activity compared with those in IHA and EHT. APA may have a higher risk of future cardiovascular events.

Reactive hyperemia occurs via activation of inwardly rectifying potassium channels and Na+/K+-ATPase in humans

RATIONALE

Reactive hyperemia (RH) in the forearm circulation is an important marker of cardiovascular health, yet the underlying vasodilator signaling pathways are controversial and thus remain unclear.

OBJECTIVE

We hypothesized that RH occurs via activation of inwardly rectifying potassium (KIR) channels and Na(+)/K(+)-ATPase and is largely independent of the combined production of the endothelial autocoids nitric oxide (NO) and prostaglandins in young healthy humans.

METHODS AND RESULTS

In 24 (23±1 years) subjects, we performed RH trials by measuring forearm blood flow (FBF; venous occlusion plethysmography) after 5 minutes of arterial occlusion. In protocol 1, we studied 2 groups of 8 subjects and assessed RH in the following conditions. For group 1, we studied control (saline), KIR channel inhibition (BaCl2), combined inhibition of KIR channels and Na(+)/K(+)-ATPase (BaCl2 and ouabain, respectively), and combined inhibition of KIR channels, Na(+)/K(+)-ATPase, NO, and prostaglandins (BaCl2, ouabain, L-NMMA [N(G)-monomethyl-L-arginine] and ketorolac, respectively). Group 2 received ouabain rather than BaCl2 in the second trial. In protocol 2 (n=8), the following 3 RH trials were performed: control; L-NMMA plus ketorolac; and L-NMMA plus ketorolac plus BaCl2 plus ouabain. All infusions were intra-arterial (brachial). Compared with control, BaCl2 significantly reduced peak FBF (-50±6%; P<0.05), whereas ouabain and L-NMMA plus ketorolac did not. Total FBF (area under the curve) was attenuated by BaCl2 (-61±3%) and ouabain (-44±12%) alone, and this effect was enhanced when combined (-87±4%), nearly abolishing RH. L-NMMA plus ketorolac did not impact total RH FBF before or after administration of BaCl2 plus ouabain.

CONCLUSIONS

Activation of KIR channels is the primary determinant of peak RH, whereas activation of both KIR channels and Na(+)/K(+)-ATPase explains nearly all of the total (AUC) RH in humans.

The antihypertensive effect of ethyl acetate extract of radish leaves in spontaneously hypertensive rats

Radish (Raphanus sativus L.) is a cruciferous vegetable, and its leaves have antioxidant and anticancer properties. This study was conducted to evaluate the effects of ethyl acetate extracts from radish leaves on hypertension in 11-week-old spontaneously hypertensive rats (SHRs). The SHRs were randomly divided into 3 groups of 6 rats each on the basis of initial systolic blood pressure (SBP) and were treated with oral administration of radish leaf extract (0, 30, or 90 mg/kg body weight [bw], respectively) for 5 weeks. Six Wistar rats were used as normotensive controls. The amount of the radish leaf extract had no effect on body weight. The SBP of the SHRs showed a decreasing trend with the consumption of the radish leaf extract. In the third week, the SBP of the group fed 90 mg extract/kg bw reduced from 214 mmHg to 166 mmHg and was significantly lower than that of the normotensive and hypertensive controls. The extract did not show a significant effect on the angiotensin-converting enzyme (ACE) activity in the serum, kidney, and lung. The extract increased the concentration of NO in serum and the activities of antioxidant enzymes such as glutathione peroxidase and catalase in red blood cells (RBCs). The serum concentrations of Na(+) and K(+) were not significantly different between all groups. However, the fecal concentrations of Na(+) and K(+) increased; the fecal concentrations of Na(+) and K(+) for the normotensive and hypertensive controls were not different. Urinary excretion of Na(+) was higher in the normotensive Wistar rats than in the SHRs, while that of K(+) was not significantly different. These findings indicate that consumption of radish leaves might have had antihypertensive effects in SHRs by increasing the serum concentration of NO and fecal concentration of Na(+) and enhancing antioxidant activities.

Endothelial function in a cardiovascular risk population with borderline ankle-brachial index

Introduction:

The diagnosis of peripheral arterial disease (PAD) can be made by measuring the ankle–brachial index (ABI). Traditionally ABI values > 1.00–1.40 have been considered normal and ABI ≤ 0.90 defines PAD. Recent studies, however, have shown that individuals with ABI values between 0.90–1.00 are also at risk of cardiovascular events. We studied this cardiovascular risk population subgroup in order to determine their endothelial function using peripheral arterial tonometry (PAT).

Methods:

We selected 66 individuals with cardiovascular risk and borderline ABI. They all had hypertension, newly diagnosed glucose disorder, metabolic syndrome, obesity, or a ten year risk of cardiovascular disease death of 5% or more according to the Systematic Coronary Risk Evaluation System (SCORE). Subjects with previously diagnosed diabetes or cardiovascular disease were excluded. Endothelial function was assessed by measuring the reactive hyperemia index (RHI) from fingertips using an Endo-PAT device.

Results:

The mean ABI was 0.95 and mean RHI 2.11. Endothelial dysfunction, defined as RHI < 1.67, was detected in 15/66 (23%) of the subjects. There were no statistically significant differences in RHI values between subjects with different cardiovascular risk factors. The only exception was that subjects with impaired fasting glucose (IFG) had slightly lower RHI values (mean RHI 1.91) than subjects without IFG (mean RHI 2.24) (P = 0.02).

Conclusions:

In a cardiovascular risk population with borderline ABI nearly every fourth subject had endothelial dysfunction, indicating an elevated risk of cardiovascular events. This might point out a subgroup of individuals in need of more aggressive treatment for their risk factors.

Doppler assessment of brachial artery flow as a measure of endothelial dysfunction in pediatric chronic renal failure

Cardiovascular morbidity and mortality are highly prevalent among patients with chronic renal failure (CRF). Endothelial dysfunction is regarded as the initial reversible step in the development of atherosclerosis and has been demonstrated in all stages of renal failure. Non-invasive techniques to assess endothelial function have been recently developed and have been proven to predict future mortality in adults. We aimed to assess endothelial function in children with stage 4 chronic kidney disease (CKD 4) on conservative treatment, using a-non invasive, high-resolution, ultrasound Doppler study of the brachial artery flow, correlating it with other clinical and laboratory parameters. This study included 34 children with CKD 4 on conservative treatment who were compared with 30 healthy controls. Flow-mediated dilatation (FMD), nitroglycerin-mediated dilatation (NTG-MD) and FMD/NTG-MD ratio were estimated. FMD was abnormal (< 5%) in 24 patients (71%). FMD and FMD/NTG-MD ratio were significantly lower in patients than in controls (P = 0.001 and P = 0.01, respectively). FMD correlated positively with serum calcium and negatively with alkaline phosphatase. We concluded that endothelial dysfunction is present in children with CKD 4 on conservative treatment and may reflect increased atherogenic and thrombogenic properties of the endothelium, contributing to subsequent adverse cardiovascular outcome.

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.

Effects of cilostazol and pentoxifylline on forearm reactive hyperemia response, lipid profile, oxidative stress, and inflammatory markers in patients with intermittent claudication

Peripheral arterial disease may lead to lower limb claudication and increased risk of systemic vascular dysfunction. In this article, the authors have investigated the peripheral vascular dysfunction evaluating forearm blood flow using venous occlusion plethysmography, lipid profile, and C-reactive protein in 60 patients with moderate intermittent claudication treated during 20 weeks with placebo (n = 16), cilostazol (200 mg/d; n = 17), or pentoxifylline (1200 mg/d; n = 15) in a randomized double-blinded clinical trial, taking into account smoking. Forearm blood flow after reactive hyperemia response (FBF(h) ) or oral nitroglycerine spray to evaluate endothelial-dependent and endothelial-independent vasodilation, respectively, pain-free and maximal walking distance, levels of C-reactive protein, triglycerides, cholesterol, low-density lipoprotein, and high-density lipoprotein-cholesterol in plasma were determined. The results showed that there was an improvement in the high-density lipoprotein-cholesterol, pain-free and maximal walking distance, and FBF(h) independent of treatment in nonsmoking patients. Cilostazol increased high-density lipoprotein-cholesterol level, maximal walking distance, and FBF(h), whereas pentoxifylline reduced C-reactive protein level and increased maximal walking distance in total and nonsmoking groups. No treatment was effective in smokers.

Pharmacological and Clinical Studies with Temocapril, an Angiotensin Converting Enzyme Inhibitor that is Excreted in the Bile

Temocapril is an angiotensin converting enzyme inhibitor (ACEI), a prodrug with a thiazepine ring. Its active form, temocaprilat, is slightly more potent than enalaprilat in inhibiting ACE isolated from rabbit lung. The inhibitory potency of temocaprilat on isolated rat aorta is 3 times that of enalaprilat. Temocapril is excreted in the bile and urine and can be used in patients with renal insufficiency. It reduces blood pressure without causing any significant change in heart rate or cardiac output. Temocapril has been reported to improve endothelial dysfunction in vitro by suppressing increased oxidative stress. In vivo it improves reactive hyperemia in patients with essential hypertension. It has been reported to prevent coronary vascular remodeling in vivo by suppressing local ACE and increased oxidative stress. In humans temocapril has been found to improve insulin resistance partly by increasing adiponectin levels. Cardiac remodeling was improved by temocapril not only in experiment animals but also in humans. It improves renal function and decreases urinary albumin excretion in diabetics as well as in hypertensive patients. Temocapril is currently marketed only in Japan. Considering its beneficial effects and unique pharmacokinetics, temocapril, is likely to be introduced in other countries as well.

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.

Endothelial dysfunction and inflammatory process in transfusion-dependent patients with beta-thalassemia major

BACKGROUND

Beta-thalassemia major is associated with increased cardiovascular risk, although the underlying mechanisms remain unclear. We examined endothelial function and serum levels of inflammatory mediators in transfusion-dependent patients with beta-thalassemia major.

METHODS

The study population consisted of 67 patients with homozygous beta-thalassemia major, (aged 24.6+/-0.7 years) and 71 healthy age and sex matched controls. Forearm blood flow was measured with gauge-strain plethysmography. Forearm vasodilatory response to reactive hyperemia (RH%) or to nitrate (NTG%) was expressed as the percentage change of forearm blood flow from baseline to the maximum flow during reactive hyperemia or sublingual nitroglycerin, respectively. Serum levels of interleukin 6 (IL-6), soluble vascular cell adhesion molecule (sVCAM-1) and soluble intercellular adhesion molecule (sICAM-1) were determined with ELISA.

RESULTS

Patients had significantly lower levels of total cholesterol (125+/-4.5 vs. 207+/-7 mg/ml, p<0.01), ApoA1 (120+/-3 vs. 129+/-5 mg/ml, p<0.05), ApoB (60.5+/-2 vs. 95+/-4 mg/ml, p<0.01), ApoE (3+/-2 vs. 4+/-0.2 mg/ml, p<0.01) and Lp(a) (7.9+/-1.3 vs. 14.5+/-3.2 mg/ml, p<0.01) than controls. IL-6 levels were significantly higher in patients (3.03+/-0.31 pg/ml) than controls (1.15+/-0.15 pg/ml, p<0.01). Similarly, sVCAM-1 and sICAM-1 levels were significantly higher in patients (513+/-31 and 368+/-25.5 ng/ml, respectively) than controls (333+/-13.8 and 272+/-14.05 ng/ml, respectively, p<0.01 for both). Maximum hyperemic forearm blood flow and RH% were lower in patients (7.1+/-0.3 ml/100 ml tissue/min and 49+/-2.8%, respectively) than controls (8.26+/-0.32 ml/100 ml tissue/min and 86.3+/-5.57%, respectively, p<0.01 for both).

CONCLUSIONS

Beta-thalassemia major is associated with impaired endothelial function and increased levels of IL-6, sVCAM-1 and sICAM-1, suggesting a potential role of inflammation and endothelial dysfunction in the complications of the disease.

A calcium-channel blocker, benidipine, improves forearm reactive hyperemia in patients with essential hypertension

The pathophysiological role of endothelial cells is important in the mechanism of progression of atherosclerosis and improvement of endothelial function may be important for cardiovascular morbidity. Calcium antagonists are reported to have protective effects on the endothelium in vitro and in vivo. In this clinical study, we investigated the effect of calcium antagonist, benidipine, on endothelial function in the patients with essential hypertension, which causes endothelial dysfunction. Twenty-five patients with hypertension without other risk factors for atherosclerosis were treated with monotherapy (8 mg benidipine, n=25) for 8 weeks. Blood pressure was reduced significantly. Endothelial function was evaluated using forearm blood flow by strain-gauge plethysmography after 8 weeks of treatment. Changes in vasodilator response to reactive hyperemia were significantly improved (p<0.01), while the response to nitroglycerin was not changed, suggesting the improvement of endothelial function. Moreover, we focused on hepatocyte growth factor (HGF), which is a novel angiogenic growth factor with an anti-apoptotic action on endothelial cells, and evaluated involvement of HGF in improvement of endothelial function. Serum HGF concentration in subjects treated with benidipine was significantly elevated at 8 weeks (p<0.05). Overall, these results demonstrated that benidipine improved endothelial dysfunction in patients with hypertension. Interestingly, an increase in serum HGF concentration by benidipine might contribute to the improvement of endothelial dysfunction.

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.

Clinical impact of vasomotor function assessment and the role of ACE-inhibitors and statins

Impaired endothelial function is recognised as one of the earliest events of atherogenesis. Endothelium-dependent vasomotion has been the principal method to assess endothelial function. In this article, we will discuss the clinical value of the different techniques to evaluate endothelium-dependent vasomotion. To date, there seems not to be a simple and reliably endothelial function test to identify asymptomatic subjects at increased risk for cardiovascular disease in clinical practice. Recent studies indicate that pharmacological interventions, in particular with ACE-inhibitors and statins, might improve endothelial function. However, there is no solid evidence that improvement of endothelial function is a necessity for the observed reduction in cardiovascular events by these compounds. Overall, at this moment, there is no place in clinical practice for the use of endothelial function as a method for risk assessment or target of pharmacological interventions.

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.

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.

Effect of nifedipine on endothelial function in normotensive smokers: potential contribution of increase in circulating hepatocyte growth factor

Calcium antagonists are reported to have protective effects on the endothelium in vitro and in vivo. Especially, nifedipine, among many calcium antagonists, was shown to improve endothelial dysfunction in patients with hypertension. However, no report has determined whether the improvement of endothelial dysfunction by nifedipine is due to direct effects or indirect effects such as its hypotensive effect. Thus, in this study, we evaluated the direct effects of nifedipine on smoking-induced endothelial dysfunction, since cigarette smoking itself is a major factor in damage of endothelial cells, as well as hypertension. We examined whether nifedipine improves endothelial function in 10 normotensive smokers without any risk factors for atherosclerosis. The subjects were treated with 20 mg nifedipine monotherapy (n = 10) or placebo (n = 10) for 4 weeks. Nifedipine did not affect blood pressure and heart rate of normotensive smokers. We measured forearm blood flow (FBF) by strain-gauge plethysmography after 2 and 4 weeks of treatment. Changes in vasodilator response to reactive hyperaemia were significantly improved in nifedipine-treated subjects (P < 0.05), while there was no significant change in FBP response in control subjects. Response to nitroglycerin was not changed in either group. Moreover, to evaluate the mechanisms of the direct effects of nifedipine on the endothelium, we focused on hepatocyte growth factor (HGF), which is a novel angiogenic growth factor with an antiapoptotic action on endothelial cells. Interestingly, serum HGF concentration in smokers treated with nifedipine was significantly elevated both at 2 and 4 weeks (P < 0.05). Overall, these results demonstrated direct effects of nifedipine in the improvement of endothelial dysfunction in normotensive smokers. The increase in serum HGF concentration by nifedipine might contribute to the improvement of endothelial dysfunction.

Effects of atorvastatin on reactive hyperaemia and the thrombosis-fibrinolysis system in patients with heart failure

OBJECTIVE

To investigate the effects of short term atorvastatin treatment on forearm vasodilatory response to reactive hyperaemia (RH%) and on components of the thrombosis-fibrinolysis system (antithrombin III, proteins and S, factors V and VII, von Willebrand factor, tissue plasminogen activator (tPA), and plasminogen activator inhibitor (PAI-1)) in patients with heart failure.

PATIENTS AND METHODS

35 patients with heart failure were enrolled in this study; 17 patients received atorvastatin 10 mg/day and 18 patients received no statin for four weeks. Forearm blood flow (FBF) was measured by venous occlusion strain gauge plethysmography. RH% and forearm vasodilatory response to nitrate were defined as the percentage change of FBF from rest to the maximum flow during reactive hyperaemia and after nitrate administration, respectively. Plasma concentrations of antithrombin III, protein C, protein S, factor V, factor VII, von Willebrand factor, tPA, and PAI-1 were determined before and after treatment.

RESULTS

Maximum hyperaemic FBF remained unchanged in both groups. Baseline FBF was slightly but not significantly decreased in the atorvastatin treated group. RH% was significantly increased only in the atorvastatin treated group, from mean (SD) 42.44 (18.9)% to 83.7 (36.1)% (p < 0.01). Plasma concentrations of antithrombin III (from mean (SD) 81.7 (11.37)% to 73.5 (13.8)%), protein C (from mean (SD) 88.3 (26.9)% to 63.9 (25.0)%), factor V (from mean (SD) 126.2 (33.4)% to 94.9 (29.8)%), tPA (from median (25th-75th percentile) 11.68 (8.60-20.95) ng/ml to 10.30 (8.65-15.12) ng/ml), and PAI-1 (from median (25th-75th percentile) 3.10 (2.15-4.40) IU/l to 1.90 (0.75-3.0) IU/l) were significantly decreased in the atorvastatin treated group (p < 0.05) but not in the control group. Plasma concentrations of von Willebrand factor, factor VII, and protein S remained unaffected in both groups.

CONCLUSION

Atorvastatin did not change the maximum hyperaemic flow, although it decreased plasma concentrations of antithrombin III, protein C, factor V, tPA, and PAI-1 in patients with heart failure. Therefore, short term treatment with atorvastatin may affect the expression of both endothelium and liver derived components of the thrombosis-fibrinolysis system in patients with heart failure.

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.

Effects of cyclooxygenase inhibition on endothelial function in hypertensive patients treated with angiotensin-converting enzyme inhibitors

BACKGROUND

Cyclooxygenase inhibition restores endothelium-dependent vasodilatation in hypertension, but it is unknown whether it restores endothelial function in hypertensive patients treated with angiotensin-converting enzyme (ACE) inhibitors.

HYPOTHESIS

The purpose of the present study was to evaluate the effects of cyclooxygenase inhibition on endothelial function in hypertensive patients treated with ACE inhibitors.

METHODS

Endothelium-dependent flow-mediated dilatation (FMD) and endothelium-independent glyceryl trinitrate-induced dilatation were investigated in 10 patients treated with enalapril (ACE group), 11 patients treated with manidipine and metoprolol (non-ACE group), and 12 normotensive control subjects. After administration of 1000 mg of aspirin, FMD was investigated once again. Plasma cyclic guanosine monophosphate (cGMP) and eicosanoids were also measured during reactive hyperemia before and after aspirin administration.

RESULTS

Flow-mediated dilatation was more impaired in the non-ACE group than in the ACE group (8.3 +/- 3.8%, 5.7 +/- 1.7%, respectively, p<0.04). Glyceryl trinitrate-induced dilatation was similar in the ACE group, the non-ACE group, and in the control subjects. In the ACE group, FMD was reduced after administration of aspirin (5.3 +/- 4.2%, p<0.05). The percent change in FMD after administration of aspirin correlated significantly with percent change in cGMP (r=0.77, p<0.03; y-intercept, -62.1%, p<0.01). After aspirin administration, levels of thromboxane B2 and 6-keto-prostaglandin(1alpha) were significantly decreased compared with those before aspirin administration in all groups.

CONCLUSIONS

Cyclooxygenase inhibition may reduce the beneficial effect on endothelium-dependent vasodilatation induced by ACE inhibitors. The results suggested that prostacyclin in addition to nitric oxide plays a significant role in the restoration of endothelial function in hypertensive patients treated with ACE inhibitors.

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.

Vascular endothelium and inflammatory process, in patients with combined Type 2 diabetes mellitus and coronary atherosclerosis: the effects of vitamin C

AIMS

Type 2 diabetes mellitus (DM) and coronary artery disease (CAD) are both associated with endothelial dysfunction and elevated oxidative and inflammatory state. We examined the effect of vitamin C on endothelial function and levels of soluble vascular cell adhesion molecule (sVCAM-1), interleukin-6 (IL-6) and tumour necrosis factor (TNF-alpha), in DM patients with or without CAD and in non-diabetic subjects.

METHODS

Thirty-seven patients with DM + CAD, 17 patients with DM without CAD and 21 non-diabetic subjects were divided into groups receiving vitamin C 2 g/day or no anti-oxidant for 4 weeks. Forearm blood flow was determined using venous occlusion gauge-strain plethysmography. Forearm vasodilatory response to reactive hyperemia was considered as index of endothelium-dependent dilation.

RESULTS

Baseline levels of IL-6 and TNF-alpha were significantly higher in patients with DM + CAD compared with patients with DM (P < 0.01) or non-diabetic subjects (P < 0.01). IL-6 and TNF-alpha levels were also higher in DM compared with non-diabetic subjects (P < 0.05). sVCAM-1 levels were lower in non-diabetic controls compared with DM + CAD (P < 0.05) or DM (P < 0.05). Reactive hyperaemia was higher in non-diabetic controls compared with DM + CAD (P < 0.001) or DM (P < 0.001). Vitamin C significantly increased reactive hyperaemia only in the DM + CAD group, while it had no effect on serum levels of sVCAM-1, TNF-alpha and IL-6 in any of the groups.

CONCLUSIONS

Type 2 diabetes mellitus is associated with impaired endothelial function and increased levels of TNF-alpha, IL-6 and sVCAM-1, especially in patients with DM and CAD. Vitamin C significantly increased forearm vasodilatory response to reactive hyperaemia only in patients with combined DM and CAD.

Acute effect of amino acid peritoneal dialysis solution on vascular function

BACKGROUND

Oral ingestion of proteins or amino acids is associated with endothelial dysfunction. The effect of commercial amino acid peritoneal dialysis solutions on vascular function is unknown.

OBJECTIVE

We compared the acute effect of intraperitoneal amino acid administration with that of intraperitoneal glucose administration on vascular function in peritoneal dialysis patients.

DESIGN

In an open-label randomized, controlled, crossover and observer-blinded trial, we examined the acute effect of an intraperitoneal application of 2 L commercial 1.1% amino acid solution compared with that of a 2.27% glucose solution in 13 peritoneal dialysis patients. The primary endpoint was the change in forearm reactive hyperemia 6 h after instillation of either dialysis solution.

RESULTS

After 6 h of dwell time, reactive hyperemia was substantially impaired after administration of the amino acid solution compared with the glucose solution (median difference: 202%; 95% CI: 57%, 368%; P = 0.007). In a comparison of differences between values at 6 h and those before treatment, reactive hyperemia significantly decreased during the dwell with the amino acid dialysis solution compared with that with the glucose dialysis solution (median difference: 242%; 95% CI: 53%, -457%; P = 0.013). In an analysis of smoking and nonsmoking patients separately, the difference in forearm blood flow between the 2 treatments was still statistically significant.

CONCLUSIONS

One 6-h dwell with a commercial amino acid dialysis solution acutely impairs forearm reactive hyperemia in smoking and nonsmoking peritoneal dialysis patients. Because endothelial dysfunction is associated with increased morbidity and mortality, the long-term use of these solutions may increase the risk of cardiovascular disease.

Vitamin C affects thrombosis/ fibrinolysis system and reactive hyperemia in patients with type 2 diabetes and coronary artery disease

OBJECTIVE

To examine the effect of vitamin C on forearm vasodilatory response to reactive hyperemia and on plasma level of plasminogen activator inhibitor 1 (PAI-1), von Willebrand factor (vWF), tissue plasminogen activator (tPA), antithrombin III (ATIII), proteins C and S, and factors V (fV) and VII (fVII) in patients with both type 2 diabetes and CAD.

RESEARCH DESIGN AND METHODS

A total of 39 patients with type 2 diabetes and CAD were divided into two groups and received vitamin C (2 g/day) or no antioxidant for 4 weeks. Forearm blood flow was determined using venous occlusion gauge-strain plethysmography at baseline and after treatment. Forearm vasodilatory response to reactive hyperemia (RH%) or nitrate (NTG%) was defined as the percent change of flow from baseline to the maximum flow during reactive hyperemia or after administration of nitrate, respectively. Biochemical markers were determined by enzyme-linked immunosorbent assay (ELISA) or other standard methods.

RESULTS

RH% was significantly increased after treatment with vitamin C (from 62.4 +/- 7.2 to 83.1 +/- 9.3%, P = 0.024) but remained unaffected in the control group. Vitamin C decreased plasma levels of fV (from 143 +/- 5.4 to 123 +/- 6.03%, P = 0.038), vWF (from 133.5 +/- 14.5 to 109.5 +/- 11.4%, P = 0.016), and tPA (from 12.3 +/- 0.99 to 8.40 +/- 0.60 ng/ml, P = 0.001), whereas these levels remained unaffected in the control group. The changes in RH%, vWF, and tPA were significantly greater (P = 0.028, 0.036, and 0.007, respectively) in the vitamin C-treated group than in the control group. Levels of ATIII, proteins S and C, fVII, and PAI-1 remained unchanged in all groups.

CONCLUSIONS

Short-term treatment with high doses of vitamin C improved RH% and decreased plasma levels of tPA and vWF in patients with type 2 diabetes and CAD.

Role of endothelial dysfunction in insulin resistance

The endothelium regulates vascular tone through the release of vasodilating and vasoconstricting substances. The most important of these vasodilating substances is nitric oxide (NO), which is also vascular protective and inhibits inflammation, oxidation, vascular smooth muscle cell proliferation, and migration. Damage to the endothelium causes endothelial dysfunction with impaired release of NO and loss of its antiatherogenic protection. Traditional risk factors for coronary artery disease, including diabetes, hypercholesterolemia, hypertension, and low levels of high-density lipoprotein cholesterol, are associated with endothelial dysfunction and thus promote the atherogenic process. More recently, insulin resistance in the absence of overt diabetes or the metabolic syndrome has been associated with endothelial dysfunction. This association provides evidence that the atherosclerotic process may actually begin earlier in the spectrum of insulin resistance, ultimately resulting in a progression of the metabolic syndrome to prediabetes and then to type 2 diabetes. Aggressive treatment of dyslipidemia and hypertension, even before the onset of type 2 diabetes, would appear prudent in decreasing the progression of the atherosclerotic process. The thiazolidinediones are peroxisome proliferator-activated receptor-gamma agonists that improve glucose and lipid metabolism. These agents have recently been shown to improve endothelial function in the early stages of insulin resistance. Results from ongoing trials with thiazolidinediones will reveal whether they will also reduce cardiovascular end points.

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.

Fluvastatin attenuates nitrate tolerance in patients with ischemic heart disease complicating hypercholesterolemia

BACKGROUND

Long-term administration of nitrates results in the development of tolerance. Nitrate tolerance is considered to occur in association with oxidative stress, although its underlying mechanisms are multi-factorial. Fluvastatin, a newly developed statin, is considered to have not only a cholesterol-lowering effect but also anti-oxidative properties.

METHODS

In this study, the effect of fluvastatin on nitrate tolerance was investigated in 12 dyslipidemic patients (nine men and three women, aged 63.5+/-6.7 years), who were complicated with ischemic heart disease and had received organic nitrates for a long period.

RESULTS

Four months after fluvastatin therapy, symptoms of angina were significantly reduced. Consumption of sublingual nitrates over 2 weeks significantly decreased (14.4+/-11.2 to 2.3+/-2.5 tablets, P<0.01). In exercise stress testing, exercise duration was significantly prolonged (275+/-73 to 360+/-86 s, P<0.01) and the blood pressure-heart rate products significantly increased (16368+/-2246 to 18381+/-1772, P<0.01). Both the percent change in forearm blood flow with reactive hyperemia (232+/-83 to 282+/-104%, P<0.05) and that after sublingual nitroglycerine (2.5+/-4.7 to 5.8+/-4.7%, P<0.05) were increased. Although the levels of total cholesterol, triglyceride, HDL-cholesterol, and LDL-cholesterol were unchanged, the serum anti-Ox-LDL titer (16.7+/-6.3 to 13.4+/-5.4 AcU/ml, P<0.05) and 8-OHdG level (1.11+/-0.34 to 0.73+/-0.34 ng/ml, P<0.05) decreased.

CONCLUSIONS

Fluvastatin attenuated nitrate tolerance in dyslipidemic patients complicated with ischemic heart disease who had been receiving organic nitrates over long period. The anti-oxidative effect of fluvastatin may attenuate nitrate tolerance.

The influence of one-year treatment by angiotensin converting enzyme inhibitor on baroreflex sensitivity and flow-mediated vasodilation of the brachial artery in essential hypertension--comparison with calcium channel blockers

BACKGROUND

Both baroreflex sensitivity and flow-mediated vasodilator function have been recognized to have prognostic significance in cardiovascular diseases. Long-term antihypertensive treatment effects on these parameters, however, remain unclear.

SUBJECTS AND METHODS

We examined the effects of long-term treatment by angiotensin converting enzyme inhibitors (ACEI) orcalcium channel blockers (CCB) on baroreflex and flow-mediated vasodilator function in patients with essential hypertension (EH). We recruited 36 patients aged 56 +/- 11 years, with systolic blood pressure > or = 160 mmHg and/or diastolic blood pressure > or = 95 mmHg. Patients were assigned either to treatment by long-acting ACEI (n = 12) or CCB (n = 24). All patients were followed for 12 months. Optimal BP was achieved by two optional increases in treatment: dose-doubling of the primary drug during the first three months and the addition of diuretics or beta-blockers thereafter. Target blood pressure was 140/90 mmHg or a fall > or = 20/10 mmHg. Baroreflex sensitivity was examined by spectral analysis of blood pressure and RR interval variabilities before treatment and after 3 and 12 months of treatment. The flow-mediated vasodilator function was determined before and 12 months after treatment by measuring the change in brachial artery diameter during increases in flow induced by reactive hyperemia.

RESULTS

Baseline blood pressures were similar between the ACEI and CCB groups (172 +/- 5/103 +/- 2 vs. 172 +/- 4/101 +/- 3 mmHg). Blood pressures after 3 and 12 months of treatment also did not differ between the ACEI and CCB groups (149 +/- 4/91 +/- 2 vs. 145 +/- 2/85 +/- 2 mmHg, and 133 +/- 5/84 +/- 2 vs. 133 +/- 2/81 +/- 2 mmHg, respectively). Baseline baroreflex sensitivity was similar between the groups (6.7 +/- 0.8 vs. 5.9 +/- 0.6 msec/mmHg). This parameter remained unchanged at three months but increased after 12 months of treatment in both the ACEI (9.5 +/- 1.6 msec/mmHg, p = 0.05) and CCB (9.1 +/- 1.2 msec/mmHg, p = 0.006) groups. Percent increases in brachial arterial diameter and flow during reactive hyperemia increased in the group treated with ACEI (12.4 +/- 3.5 vs. 25.8 +/- 6.3% and 618 +/- 72 vs. 953 +/- 166, p < 0.05 for both) but both parameters remained unchanged in the group treated with CCB.

CONCLUSION

These data suggest that long-term blood pressure control with modem antihypertensive drugs improves baroreflex function. Treatment with ACEI may be more favorable for flow-mediated vasodilator function than treatment with CCB.

Efficacy of Various Antihypertensive Agents as Evaluated by Indices of Vascular Stiffness in Elderly Hypertensive Patients

When observed in elderly hypertensive patients, increased pulse pressure (PP) and arterial stiffness are known to be independent risk factors for cardiovascular diseases. Increased systolic blood pressure (SBP) leads to left ventricular hypertrophy, while decreased diastolic blood pressure (DBP) results in decreased coronary circulation. It is known that increased arterial stiffness is the major cause of increased PP. Thus basic morbid states of cardiac failure or ischemic heart diseases are more likely to develop in elderly hypertensive patients with increased PP and arterial stiffness, and there is need of antihypertensive drugs that decrease these effects in elderly hypertensives. In this study, we compared the effects of an angiotensin-receptor blocker (ARB: valsartan), an angiotensin-converting enzyme inhibitor (ACE-I: temocapril), and long-acting Ca antagonists (L- and N-type Ca channel blocker: cilnidipine; and L-type Ca channel blocker: nifedipine CR) on PP and arterial stiffness measured by pulse wave velocity in elderly hypertensive patients for 3 months. The ARB yielded the largest reductions in PP and brachial-ankle pulse wave velocity (baPWV), followed by the ACE-I and L- and N-type Ca channel blocker, while the L-type Ca channel blocker yielded no improvement. The effects on arterial stiffness and PP thus varied among the drug characteristics. Although ARB achieved the largest reduction in baPWV, this decrease was not associated with any reductions in PP, SBP, DBP, or mean blood pressure, as were the baPWV-decreases achieved by the other drugs, suggesting that ARB may further reduce the risk of arteriosclerosis in elderly hypertensive patients by decreasing arterial stiffness in addition to its antihypertensive effect.

Effects of folate treatment and homocysteine lowering on resistance vessel reactivity in atherosclerotic subjects

Hyperhomocysteinemia is associated with arterial hypertension and endothelial dysfunction in healthy humans. Placebo-controlled vitamin intervention studies cannot distinguish intrinsic actions of homocysteine (tHcy) and folate concentrations on the endothelium. The present two-period crossover study investigates the effects of tHcy lowering through oral folic acid on antioxidant status and resistance vessel reactivity in patients with established coronary artery disease (CAD). We investigated 27 male patients with angiographically documented multivessel CAD aged 50 (range 46-56) years. Resistance vessel reactivity was assessed by measurement of postischemic reactive hyperemia (RH) in the forearm using venous occlusion plethysmography at baseline, after 6 weeks of treatment with 5 mg of oral folic acid, and after a washout period of another 6 weeks. Plasma folate increased 3.49-fold with a mean tHcy reduction of 21.3%. Peak reactivity of resistance vessels improved significantly (18.97-23.60 ml/min(-1) per 100 ml; P = 0.01) with unchanged total antioxidant status (TAS; 0.912-0.944 microM; P = 0.4). This effect was limited to subjects (n = 14) with a tHcy reduction >2 microM (median reduction, 14.4-9.6 microM, P < 0.001). In the 13 subjects with a below-median reduction, tHcy remained unaltered (9.7-9.6 microM, P = 0.88) and TAS increased significantly (0.923-1.055 microM, P = 0.006), whereas RH peak flow was not affected (20.22-22.99 ml/min(-1) per 100 ml, P = 0.28). Homocysteine lowering >2 microM through folic acid supplementation improves resistance vessel reactivity in patients with CAD. Our data support the hypothesis that homocysteine lowering may have intrinsic vasoprotective effects largely independent of folate.

Prognostic role of reversible endothelial dysfunction in hypertensive postmenopausal women

OBJECTIVES

; The aim of the present study was to assess whether optimized antihypertensive treatment is effective in modifying endothelial function and whether an improvement in flow-mediated vasodilation (FMD) in response to treatment, as an expression of reversible endothelial dysfunction, could predict a more favorable prognosis in a population of postmenopausal women.

BACKGROUND

Hypertensive postmenopausal women have been shown to have abnormal endothelium-dependent vascular function. However, FMD may change over time, according to antihypertensive treatment; the prognostic value of these changes has not been investigated.

METHODS

A total of 400 consecutive postmenopausal women with mild-to-moderate hypertension and impaired FMD underwent ultrasonography of the brachial artery at baseline and after six months, while optimal control of blood pressure was achieved using antihypertensive therapy. They were then followed up for a mean period of 67 months (range 57 to 78). Endothelial function was measured as FMD of the brachial artery, using high-resolution ultrasound.

RESULTS

After six months of treatment, FMD had not changed (< or = 10% relative to baseline) in 150 (37.5%) of 400 women (group 1), whereas it had significantly improved (>10% relative to baseline) in the remaining 250 women (62.5%) (group 2). During follow-up, we noticed 32 events (3.50 per 100 person-years) in group 1 and 15 events (0.51 per 100 person-years) in group 2 (p < 0.0001).

CONCLUSIONS

This study demonstrates that a significant improvement in endothelial function may be obtained after six months of antihypertensive therapy and clearly identifies patients who possibly have a more favorable prognosis.

Endothelial function and oxidative stress in renovascular hypertension

BACKGROUND

It has been reported that renovascular hypertension activates the renin-angiotensin system, leading to an increase in oxidative stress. We sought to determine whether renal-artery angioplasty improves endothelial dysfunction in patients with renovascular hypertension through a reduction in oxidative stress.

METHODS

We evaluated the response of forearm blood flow to acetylcholine, an endothelium-dependent vasodilator, and isosorbide dinitrate, an endothelium-independent vasodilator, before and after renal-artery angioplasty in 15 subjects with renovascular hypertension and 15 controls without hypertension who were matched for age and sex. Forearm blood flow was measured with the use of a mercury-filled Silastic strain-gauge plethysmograph.

RESULTS

The forearm blood flow in response to acetylcholine was less in subjects with renovascular hypertension than in controls, although the forearm blood flow in response to isosorbide dinitrate was similar in the two groups. Angioplasty decreased systolic and diastolic blood pressures, forearm vascular resistance, and urinary excretion of 8-hydroxy-2'-deoxyguanosine and serum malondialdehyde-modified low-density lipoprotein (LDL), indexes of oxidative stress. After angioplasty, the mean (+/-SD) forearm blood flow in response to acetylcholine was increased in the patients with renovascular hypertension (19.3+/-6.8 vs. 29.6+/-7.1 ml per minute per 100 ml, P=0.002). The increase in the maximal forearm blood flow in response to acetylcholine correlated significantly with the decrease in urinary excretion of 8-hydroxy-2'-deoxyguanosine (r=-0.51, P=0.004) and serum malondialdehyde-modified LDL (r=-0.39, P=0.02). Coinfusion of ascorbic acid (vitamin C) augmented the response of forearm blood flow to acetylcholine before angioplasty (P<0.001) but not after angioplasty.

CONCLUSIONS

These findings suggest that excessive oxidative stress is involved, at least in part, in impaired endothelium-dependent vasodilatation in patients with renovascular hypertension.

Serum hepatocyte growth factor concentration is correlated with the forearm vasodilator response in hypertensive patients

To evaluate the clinical importance of serum hepatocyte growth factor (HGF) concentration, we designed two clinical investigations. The first study analyzed the correlation between serum HGF concentration and clinical arterial stiffness or the vasodilator response to reactive hyperemia in hypertensive patients. The second study investigated the correlation between changes in serum HGF concentration and clinical arterial stiffness or reactive hyperemia during treatment with cilazapril or atenolol. A total of 210 hypertensive patients were analyzed in the first study, and 25 patients with essential hypertension were evaluated in the second study. Pulse wave velocity (PWV), strain gauge plethysmography, and serum HGF concentration were measured in the first study. We also evaluated these factors before and after treatment with either cilazapril (2.0 mg/day) or atenolol (25 mg/day) for 6 months in the second study. Serum HGF concentration was negatively correlated to reactive hyperemia in overall (r = 0.434, P < .0001) and nontreatment (r = 0.452, P < .0001) hypertensive patients. Arterial stiffness was weakly related to serum HGF concentration (P < .05) after adjusting for age and mean blood pressure (BP). By multiple regression analysis, only serum HGF concentration showed a strong independent correlation with reactive hyperemia, age and mean BP with PWV. Moreover, a relationship between endothelium-dependent vasodilation and serum HGF concentration was observed during treatment with cilazapril or atenolol (r = 0.406, P < .005). These results suggest that in evaluation of serum HGF concentration, the forearm vasodilator response to reactive hyperemia and PWV might be useful for managing hypertension in patients who are receiving antihypertensive therapy.

Improvement of endothelial function by amlodipine and vitamin C in essential hypertension

BACKGROUND

The effects of antihypertensive agents on endothelial function have not been fully evaluated in human hypertension and data on the forearm circulation of humans are controversial. The aim of this study was (1) to evaluate the endothelial function in hypertensive patients (2) to investigate whether vitamin C administration has any benefit on the endothelial function and (3) to determine whether treatment with calcium antagonist improves endothelial dysfunction in hypertensive patients.

METHODS

The endothelial function was estimated using venous occlusion plethysmography (VOP) in 8 hypertensive patients and 8 healthy volunteers. The patients in the hypertension group were treated with amlodipine, then examined again. The change of forearm blood flow (FBF) was measured with acetylcholine infusion through brachial artery and also with intra-arterial vitamin C.

RESULTS

Forearm blood flow response to acetylcholine was significantly enhanced with intra-arterial infusion of vitamin C in hypertensive group before antihypertensive treatment. Co-infusion of L-NMMA, an inhibitor of nitric oxide synthase, blunted forearm blood flow response to acetylcholine. After treatment with amlodipine for 2 months in hypertensive group, endothelium-dependent vasorelaxation to acetylcholine was significantly improved compared to pretreatment, and vitamin C did not affect the improved endothelial function by amlodipine treatment.

CONCLUSION

Vitamin C (acutely) and amlodipine (chronically) improved endothelial function in hypertensive patients. These results suggest that increased oxidative stress, at least in part, may be involved in the decreased endothelial function in hypertension.

Severity of hypertension affects improved resistance artery endothelial function by angiotensin-converting enzyme inhibition

The purpose of this study was to determine whether there are differences in the restoration of endothelial function by angiotensin-converting enzyme inhibition based on the severity of hypertension. Forearm blood flow (FBF) was measured in 69 patients with essential hypertension (mild, n = 23; moderate, n = 29; and severe, n = 17 randomly assigned to treatment with either imidapril or amlodipine for 24 weeks in a double-blind fashion during reactive hyperemia and after sublingual administration of nitroglycerin. Imidapril augmented the FBF response to reactive hyperemia after 24 weeks of treatment in the mild and moderate hypertensive groups, but not in the severe hypertensive group. The augmentation of the FBF response to reactive hyperemia induced by imidapril was significantly greater in the moderate hypertensive group than in the mild hypertensive group. Amlodipine did not alter the FBF response to reactive hyperemia. The increase in FBF after the sublingually administered nitroglycerin was similar in all groups. The infusion of NG-monomethyl-l-arginine, a nitric oxide synthase inhibitor, abolished the enhancement of reactive hyperemia in the mild and moderate hypertensive groups treated with imidapril. These findings suggest that the effects of imidapril on endothelial function are affected by the severity of hypertension and that angiotensin-converting enzyme inhibitor-induced augmentation of reactive hyperemia may be due to increased nitric oxide production.

Lowering of blood pressure improves endothelial dysfunction by increase of nitric oxide production in hypertensive rats

To investigate the effects of angiotensin converting enzyme inhibitor (ACE-I) and other antihypertensive agents on the nitric oxide (NO) release during hypertension, seven- and fourteen-week-old SHR and deoxycorticosterone acetate (DOCA)-salt rats were treated with hydralazine, manidipine (Ca antagonist) or quinapril (ACE-I) for 3 weeks to lower blood pressure. Systolic blood pressure (SBP) was measured by the tail cuff method once each week. Endothelial cells (ECs) derived from the descending aorta of the treated rats were cultured and NOx levels in culture media were measured with an NO analyzer based on the Griess reaction. In both SHR and DOCA-salt rats, antihypertensive therapy lowered SBP to levels similar to those of control rats. The only exception was quinapril treatment of DOCA-salt rats. Although NOx release by ECs derived from hypertensive rats was improved by antihypertensive therapy, the effect was most pronounced in SHR treated with quinapril. In addition, restoration of NOx release was much more remarkable in younger SHR. NOx release was significantly higher in DOCA-salt rats treated with quinapril than in control rats without reduction of SBP. These results suggest that lowering blood pressure improves release of NO by ECs during hypertension and that the time at which antihypertensive therapy is started is also important to preserve endothelial function. Furthermore, ACE-I is suggested to protect endothelial function by increasing NO production in addition to lowering blood pressure.

Lipid-lowering therapy with fluvastatin inhibits oxidative modification of low density lipoprotein and improves vascular endothelial function in hypercholesterolemic patients

This prospective randomized trial was designed to elucidate clinically the effect of fluvastatin on inhibiting oxidation of the low density lipoprotein (LDL) and improving the vascular endothelial function as well as its lipid-lowering effects, in comparison with pravastatin. Of 64 consecutive dyslipidemic patients, 40 patients, whose level of total cholesterol or LDL-cholesterol maintained the criteria of the hypercholesterolemia in spite of 12-week dietary therapy, were randomly assigned to receive either fluvastatin (n=20) or pravastatin (n=20). We assessed the titer of antibody against oxidized LDL (anti-Ox-LDL) as a biomarker for LDL-oxidation, and the forearm blood flow response during reactive hyperemia by venous occlusion plethysmography, which indicates the endothelium-dependent vasodilator capacity. After the 16-week lipid-lowering therapy, the anti-Ox-LDL titer significantly decreased in the fluvastatin group (P<0.01) but did not change in the pravastatin group. The percent increase in the forearm blood flow at the peak reactive hyperemia from the baseline value (%RH) significantly increased in the fluvastatin group (P<0.001) but did not change in the pravastatin group. The ratio of the %RH after the therapy over the baseline value negatively correlated with that of the anti-Ox-LDL titer (R=0.73, P<0.001) in all patients. Fluvastatin may serve as an ideal drug for reducing the risk of atherosclerosis, not only by its cholesterol-lowering effect but also by its unique effects of inhibiting LDL oxidation and improving the vascular endothelial function.

Estrogen replacement therapy in postmenopausal women augments reactive hyperemia in the forearm by reducing angiotensin converting enzyme activity

The precise mechanism of the vasoprotective effect of estrogen replacement therapy in postmenopausal women is not fully understood. The present study sought to determine the role of nitric oxide (NO) and angiotensin-converting enzyme (ACE) in the vasodilator response of the forearm vessels induced by estrogen administration to postmenopausal women. Subjects were divided into two groups. One group received conjugated equine estrogen (0.625 mg daily) orally for 3 months (n=26), while the other received no treatment (control group, n=10). Forearm blood flow was measured by strain-gauge plethysmography. The concentrations of nitrite/nitrate (metabolites of NO), ACE activity, and lipid parameters were measured. Basal forearm blood flow, body weight, blood pressure, and heart rate were similar at baseline in both groups. After 3 months of estrogen administration, the maximal forearm blood flow response during reactive hyperemia and the serum level of nitrite/nitrate each showed a significant increase over baseline values: from 23.6+/-2.0 to 36.5+/-3.1 ml/min per 100 ml tissue (P<0.01), and from 24.8+/-2.3 to 38.6+/-3.6 micromol/l (P<0.01), respectively. Plasma levels of ACE activity were significantly reduced from baseline after 3 months of estrogen treatment (from 12.2+/-0.6 to 10.9+/-0.6 IU/l, P<0.01). No changes were seen in controls. The change in forearm blood flow after sublingual nitroglycerin was similar at baseline versus after 3 months of estrogen administration. The increase in the serum level of nitrite/nitrate after 3 months of estrogen therapy showed a significant inverse correlation (r=0.52, P<0.01) with the reduction in the plasma level of ACE activity. There was no significant correlation between the increase in serum nitrite/nitrate and any change in serum lipids, blood pressure, or other parameters. The administration of oral estrogen to postmenopausal women for 3 months increased the NO-mediated forearm endothelium-dependent vasodilatation. This was likely due, at least in part, to ACE inhibition. The latter may be one mechanism by which ERT provides its well-known cardiovascular benefit.

Repeated thermal therapy improves impaired vascular endothelial function in patients with coronary risk factors

OBJECTIVES

We sought to determine whether sauna therapy, a thermal vasodilation therapy, improves endothelial function in patients with coronary risk factors such as hypercholesterolemia, hypertension, diabetes mellitus and smoking.

BACKGROUND

Exposure to heat is widely used as a traditional therapy in many different cultures. We have recently found that repeated sauna therapy improves endothelial and cardiac function in patients with chronic heart failure.

METHODS

Twenty-five men with at least one coronary risk factor (risk group: 38 +/- 7 years) and 10 healthy men without coronary risk factors (control group: 35 +/- 8 years) were enrolled. Patients in the risk group were treated with a 60 degrees C far infrared-ray dry sauna bath for 15 min and then kept in a bed covered with blankets for 30 min once a day for two weeks. To assess endothelial function, brachial artery diameter was measured at rest, during reactive hyperemia (flow-mediated endothelium-dependent dilation [%FMD]), again at rest and after sublingual nitroglycerin administration (endothelium-independent vasodilation [%NTG]) using high-resolution ultrasound.

RESULTS

The %FMD was significantly impaired in the risk group compared with the control group (4.0 +/- 1.7% vs. 8.2 +/- 2.7%, p < 0.0001), while %NTG was similar (18.7 +/- 4.2% vs. 20.4 +/- 5.1%). Two weeks of sauna therapy significantly improved %FMD in the risk group (4.0 +/- 1.7% to 5.8 +/- 1.3%, p < 0.001). In contrast, %NTG did not change after two weeks of sauna therapy (18.7 +/- 4.2% to 18.1 +/- 4.1%).

CONCLUSIONS

Repeated sauna treatment improves impaired vascular endothelial function in the setting of coronary risk factors, suggesting a therapeutic role for sauna treatment in patients with risk factors for atherosclerosis.

Effect of chronic angiotensin II inhibition on the nitric oxide synthase in the normal rat during aging

OBJECTIVE

To assess the effect on the cardiovascular system, of enalapril (E) or losartan (L) given since weaning during 6 or 18 months to normal rats.

METHODS

Animals were divided in three groups: control (C), E-treated and L-treated; treated rats received 10 mg/ kg per day of drug. Systolic blood pressure (SBP), body weight, water and food intake (WI, FI), cardiac, left ventricular and aortic weight as well as the length of the tail were recorded. NADPH-diaphorase activity was determined as a marker of nitric oxide synthase (NOS) activity in aorta, arterioles of small intestine, heart and kidney of normal rats. NOS activity was measured as optical density (OD) in the stained tissue. Nitrate + nitrite urinary excretion was measured in 24 h urine. Only significant differences (P < 0.05) are reported.

RESULTS

SBP, absolute cardiac, left ventricular and aortic weight increased with age. Both treatments delayed these increments. At 6 and 18 months, NOS activity was higher in aortic endothelium (Em) of L- and E-treated animals. Losartan treatment during 6 months also increased NOS activity in aortic smooth muscle (SM). Aortic Em NOS activity fell in the 18 months-treated and untreated animals. E increased NOS activity in the SM of intestinal arterioles at 6 months but reduced it at 18 months.

CONCLUSIONS

The fact that both E and L delayed cardiac hypertrophy/hyperplasia and aortic growth and raised aortic endothelium NOS activity indicates a protective effect on cardiovascular damage due to aging, exerted through inhibition of angiotensin II.

Postprandial impairment of resistance vessel function in insulin treated patients with diabetes mellitus type-2

Reduced postischaemic reactive hyperaemia, is considered a marker of impaired resistance vessel function. Acute postprandial hyperlipidaemia has been shown to induce vascular dysfunction. In the present study, the impact of postprandial hyperglycaemia on resistance vessel reactivity was investigated in insulin treated type-2 diabetic patients. The study was performed in 16 insulin treated type-2 diabetics (eight male/eight female, age 47 +/- 3 years, HbA1c 7.2 +/- 0.2) and 16 controls. Reactive hyperaemia was measured in the forearm by venous occlusion plethysmography after 5 min of ischaemia in the fasting state and 90 min after a test meal. In diabetics, blood glucose increased from 8.7 +/- 1.1 to 15.3 +/- 1.0 mmol l-1 (P<0.001) postprandially. This resulted in (i) a significant increase of resting blood flow (3.4 +/- 0.3 to 4.8 +/- 0.4 ml min-1 100 ml-1, P<0.01) and (ii) in a reduced peak reactive hyperaemia (52.3 +/- 7.4 to 36.8 +/- 4.3 ml min-1 100 ml-1, P<0.005). In controls, a similar effect of the meal on resting flow was observed but reactive hyperaemia was unaltered. In the absence of a test meal, basal flow as well as peak reactive hyperaemia remained unchanged in diabetic as well as in non-diabetic subjects. Our data provide evidence that in the postprandial state resistance vessel reactivity becomes reduced in insulin treated type-2 diabetic patients.