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Endothelium-derived microparticles impair endothelial function in vitro.

Endothelial cell dysfunction (ECD) is emerging as the common denominator for diverse and highly prevalent cardiovascular diseases. Recently, an increased number of procoagulant circulating endothelial microparticles (EMPs) has been identified in patients with acute myocardial ischemia, preeclampsia, and diabetes, which suggests that these particles represent a surrogate marker of ECD. Our previous studies showed procoagulant potential of endothelial microparticles and mobilization of microparticles by PAI-1. The aim of this study was to test the effects of isolated EMPs on the vascular endothelium. EMPs impaired ACh-induced vasorelaxation and nitric oxide production by aortic rings obtained from Sprague-Dawley rats in a concentration-dependent manner. This effect was accompanied by increased superoxide production by aortic rings and cultured endothelial cells that were coincubated with EMPs and was inhibited by a SOD mimetic and blunted by an endothelial nitric oxide synthase inhibitor. Superoxide was also produced by isolated EMP. In addition, p22(phox) subunit of NADPH-oxidase was detected in EMP. Our data strongly suggest that circulating EMPs directly affect the endothelium and thus not only act as a marker for ECD but also aggravate preexisting ECD.

Animals↗

A single air dive reduces arterial endothelial function in man.

During and after decompression from dives, gas bubbles are regularly observed in the right ventricular outflow tract. A number of studies have documented that these bubbles can lead to endothelial dysfunction in the pulmonary artery but no data exist on the effect of diving on arterial endothelial function. The present study investigated if diving or oxygen breathing would influence endothelial arterial function in man. A total of 21 divers participated in this study. Nine healthy experienced male divers with a mean age of 31 +/- 5 years were compressed in a hyperbaric chamber to 280 kPa at a rate of 100 kPa min(-1) breathing air and remaining at pressure for 80 min. The ascent rate during decompression was 9 kPa min(-1) with a 7 min stop at 130 kPa (US Navy procedure). Another group of five experienced male divers (31 +/- 6 years) breathed 60% oxygen (corresponding to the oxygen tension of air at 280 kPa) for 80 min. Before and after exposure, endothelial function was assessed in both groups as flow-mediated dilatation (FMD) by ultrasound in the brachial artery. The results were compared to data obtained from a group of seven healthy individuals of the same age who had never dived. The dive produced few vascular bubbles, but a significant arterial diameter increase from 4.5 +/- 0.7 to 4.8 +/- 0.8 mm (mean +/- s.d.) and a significant reduction of FMD from 9.2 +/- 6.9 to 5.0 +/- 6.7% were observed as an indication of reduced endothelial function. In the group breathing oxygen, arterial diameter increased significantly from 4.4 +/- 0.3 mm to 4.7 +/- 0.3 mm, while FMD showed an insignificant decrease. Oxygen breathing did not decrease nitroglycerine-induced dilatation significantly. In the normal controls the arterial diameter and FMD were 4.1 +/- 0.4 mm and 7.7 +/- 0.2.8%, respectively. This study shows that diving can lead to acute arterial endothelial dysfunction in man and that oxygen breathing will increase arterial diameter after return to breathing air. Further studies are needed to determine if these mechanisms are involved in tissue injury following diving.

Adult↗

Effects of Angiotensin-converting enzyme inhibition and statin treatment on inflammatory markers and endothelial functions in patients with longterm rheumatoid arthritis.

OBJECTIVE: To investigate the effects of angiotensin-converting enzyme (ACE) inhibitors and statins (hydroxy-methyl-glutaryl-CoA reductase inhibitors) on inflammatory markers and endothelial functions in patients with rheumatoid arthritis (RA). METHODS: A total of 45 patients with longterm RA were randomized into 3 groups to receive 8 weeks of treatment with placebo (n = 15), simvastatin (20 mg/day, n = 15), or quinapril (10 mg/day, n = 15) as an adjunct to existing antirheumatic drug treatment. Factors with a role in the development of endothelial dysfunction, such as C-reactive protein (CRP), fibrinogen, nitric oxide (NO), and serum cytokine concentrations including interleukin 1beta (IL-1beta), IL-6, and tumor necrosis factor-alpha (TNF-alpha) were measured at baseline and in the posttreatment period. Brachial artery vasodilator responses were assessed by high resolution ultrasound to evaluate endothelial functions. RESULTS: Simvastatin treatment significantly decreased serum CRP and TNF-a [from 14 +/- 6 to 7 +/- 3 mg/l (p = 0.025) and 30 +/- 5 to 16 +/- 4 pg/ml (p = 0.012), respectively], while quinapril had no significant changes in these 2 measures. IL-1beta and IL-6 showed insignificant changes in patients in the 2 drug groups. Endothelium-dependent vasodilatation was improved significantly in the simvastatin group [from 5.3 +/- 1.1% to 8.9 +/- 1.4% (p = 0.025)], while there was no difference in endothelium-independent vasodilatation [9.0 +/- 1.8% to 11.2 +/- 2.5% (p = 0.17)]. The quinapril group showed no significant changes in both types of vasodilation although there was a tendency to an increase in endothelium-dependent vasodilatation [from 6.1 +/- 0.8% to 7.8 +/- 0.7% (p = 0.06)]. Treatment with the 2 drugs had no significant effects on resting arterial diameter. CONCLUSION: We show that simvastatin 20 mg daily improves endothelial function in patients with RA. Its beneficial effect may be attributed to lowering CRP and TNF-alpha concentrations. ACE inhibition with daily 10 mg quinapril was found to have no significant effects on inflammatory markers and endothelial vasodilator response.

Adult↗

Endothelial function, variables of fibrinolysis and coagulation in smokers and healthy controls.

OBJECTIVE: To asses endothelial function and variables of fibrinolysis and coagulation in smokers compared to healthy controls. METHODS: Flow-associated dilation as a marker for peripheral endothelial function and intima media thickness as a marker for early morphologic vascular changes were measured in otherwise healthy smokers (n = 30, 16 males and 14 females, age: 40.6 +/- 11.3 years, body mass index 24.9 +/- 3.7 kg/m(2)) and non-smoking controls matched for age and sex using high-resolution ultrasound. Variables of the coagulation system (thrombin-antithrombin III complex, fibrinogen) and fibrinolysis (tissue-plasminogen activator, plasmin-alpha(2)-antiplasmin complex) were determined by ELISA and plasminogen activator inhibitor activity by means of a chromogenic substrate test. RESULTS: Compared to the non-smoking controls, flow-associated vasodilatation was significantly reduced (6.9 +/- 4. 4 vs. 10.5 +/- 6.2%, p = 0.01) and intima media thickness tended to be increased (0.58 +/- 0.12 vs. 0.52 +/- 0.14 mm, p = 0.08) in smokers. The thrombin-antithrombin III complex, fibrinogen, plasmin-alpha(2)-antiplasmin complex, tissue-plasminogen activator and plasminogen activator inhibitor activity did not differ between smokers and controls. CONCLUSION: Our data indicate that peripheral endothelial dysfunction is common in smokers even without major alterations in molecular markers of the coagulation and fibrinolysis system.

Adult↗

Effect of fat and carbohydrate consumption on endothelial function.

Consumption of a meal high in monounsaturated fat was associated with acute impairment of endothelial function when compared with a carbohydrate-rich meal. Such a divergent response in endothelial function may be important in the modulation of vascular function in health and disease.

Adult↗

Vascular endothelial function in patients with slow coronary flow.

BACKGROUND: Slow coronary flow (SCF) in a normal coronary angiogram is a well-recognized clinical entity, but its etiopathogenesis remains unclear. DESIGN: The aim of the study was to determine endothelial function in patients with SCF using a flow-mediated dilatation (FMD) technique in the brachial artery. METHODS: Coronary flow was quantified using the corrected thrombosis in myocardial infarction (TIMI) frame count (CTFC) method. Endothelial function was studied in 27 patients with SCF (23 men, four women, mean age 47.6+/-8.7 years) and in 30 people with normal coronary flow (NCF) (22 men and eight women, mean age 47.5+/-7.4 years). RESULTS: The flow-mediated diameter increase in the SCF group was significantly smaller than that in the NCF group (3.48+/-0.10% compared with 9.11+/-0.10%, P < 0.001). The percentage of nitroglycerine (NTG)-induced dilatation was not significantly different between patients with SCF and people with NCF (16.8+/-1.1% compared with 17.1+/-1.1%, P = 0.87). Simple regression analysis showed that mean CTFC (CTFC(m)) was strongly and inversely related to the percentage of FMD (r = -0.29, P < 0.01) in all participants. When the patients with SCF were excluded, CTFC(m) was still inversely related to the percentage of FMD (r = -0.36, P < 0.05). CTFC(m) was also inversely related to NTG-induced dilatation in the 57 participants (r = -0.23, P < 0.05). Multiple regression analysis showed that CTFC(m) was inversely related to the percentage of FMD only (r = -0.37, P < 0.05). CONCLUSIONS: These findings suggest that endothelial function is impaired in people with SCF and that CTFC correlates well with endothelial dysfunction.

Adult↗

Acute and chronic oral magnesium supplementation: effects on endothelial function, exercise capacity, and quality of life in patients with symptomatic heart failure.

Endothelial dysfunction is an important pathophysiologic mechanism in the progression of heart failure. The objective of the present study was to determine the effects of acute and chronic oral magnesium supplementation on endothelial function in patients with symptomatic heart failure. Twenty-two symptomatic chronic heart failure patients were randomized to receive 800 mg oral magnesium oxide daily or placebo for 3 months. Data collected included large and small arterial elasticity/compliance, hemodynamic parameters, exercise capacity, and quality-of-life score at baseline, 1 week, and 3 months. Patients who received magnesium had improved small arterial compliance at 3 months from baseline compared with placebo. This study suggests that chronic supplementation with oral magnesium is well tolerated and could improve endothelial function in symptomatic heart failure patients.

Aged↗

Normal endothelial function after meals rich in olive or safflower oil previously used for deep frying.

BACKGROUND AND AIM: Polyunsaturated fats are more susceptible to oxidation during heating than monounsaturated fats but their effects on endothelial function when heated are unknown. The aim of this study was to compare the effect of meals rich in heat-modified safflower and olive oils on postprandial flow-mediated endothelium-dependent dilation (EDD) in healthy men. METHODS AND RESULTS: Flow-mediated EDD and glyceryltrinitrate-induced endothelium-independent dilation of the brachial artery were investigated in 14 subjects before and 4 hours after meals rich in olive oil and safflower oil used hourly for deep-frying for 8 hours in a double-blind crossover study design. There were high levels of lipid oxidation products (peroxides and carbonyls) in both heated oils. Plasma triglycerides were markedly increased at 4 hours after heated olive oil (1.26 +/- 0.43 vs 2.06 +/- 0.97 mmol/L) and heated safflower oil (1.44 +/- 0.63 vs 1.99 +/- 0.88 mmol/L). There was no change in EDD between fasting and postprandial studies and the response during the postprandial period was not significantly (p = 0.51) different between the meals (heated olive oil: 4.9 +/- 2.2% vs 4.9 +/- 2.5%; heated safflower oil: 5.1 +/- 3.1% vs 5.6 +/- 3.4%). CONCLUSIONS: Meals rich in olive and safflower oils previously used for deep frying and containing high levels of lipid oxidation products increase postprandial serum triglycerides without affecting endothelial function. These findings suggest that relatively short-term use of these vegetable oils for frying may not adversely affect postprandial endothelial function when foods containing the heat-modified oils are consumed.

Adult↗

Phytoestrogens do not influence lipoprotein levels or endothelial function in healthy, postmenopausal women.

Plant estrogen or phytoestrogens (PE) are increasingly consumed for the purposes of menopause symptom relief and prevention of cardiovascular and other diseases. The objective of this study was to evaluate the effects of PE on plasma lipids and lipoproteins and on endothelial function. Twenty healthy, postmenopausal women, 50 to 70 years old, and with evidence of endothelial dysfunction, were treated with a soybean PE tablet of 80 mg/day of isoflavones. Endothelial function was assessed noninvasively using brachial ultrasound. A double-blind, placebo-controlled, randomized crossover design was employed. After 3 weeks stabilization on a standard fat-reduced diet, subjects received PE or placebo for 8 weeks in random order, separated by a washout period of 8 weeks. Compared with placebo, there were no significant effects of PE on blood pressure and plasma lipid or lipoprotein concentrations. Flow-mediated endothelium-dependent dilation (FMD) in response to reactive hyperemia was not significantly changed by PE ingestion (3. 3 +/- 0.7% on placebo vs 4.1 +/- 0.7% on PE, p >0.4). Variation in FMD was not correlated with change in plasma isoflavone concentration (r = -0.09, p >0.7). Glyceryl trinitrate endothelium-independent dilation was not significantly changed with PE (15.9 +/- 1.3% vs 13.7 +/- 1.2%, p >0.1). These results fail to show a significant impact of medium-term supplementation with 80 mg/day of isoflavones on lipid and lipoprotein levels or on endothelial function in healthy, postmenopausal women.

Aged↗

Novel topical thiadiazoles and benzothiazoles as pharmacological probes of corneal endothelial function.

Corneal transparency is maintained by an active transport system, located at the endothelial cell membranes. This bicarbonate-dependent pump counteracts the tendency of the corneal stroma to absorb water, swell and become opaque. Carbonic anhydrase inhibitors (CAI) are capable of attenuating the bicarbonate efflux, therefore causing thickening of the cornea. Eight novel sulfonamides were evaluated as potential probes for assessing the corneal endothelial functional reserves. Five of the six thiadiazoles and both benzothiazoles have demonstrated carbonic anhydrase inhibitory properties in vitro. Of the eight compounds tested, 2-ethyladipoyl-1,3,4-thiadiazole-5-sulfonamide (compounds III), 2-epoxy-1,3,4-thiadiazole-5-sulfonamide (compound V), and 2-acetamido-1,3,4-thiadiazole-5-N-methylsulfonamide (compound VI) have induced reversible corneal thickening. Although statistically significant (p < 0.05), the magnitude of the pachymetric effect did not exceed 6-10% of the total corneal thickness, probably because carbonic anhydrase (CA) is only one component of the active pump complex. The fact that a non-CAI (compound VI) was capable of inducing a reversible corneal thickening may suggest that other mechanisms are involved. Further studies will be conducted to identify a pharmacological agent capable of reversibly inhibiting the endothelial function in normal and diseased corneas, with a higher magnitude of effect.

Administration, Topical↗

Endothelial function, insulin action and cardiovascular risk factors in young healthy adult offspring of parents with Type 2 diabetes: effect of vitamin E in a randomized double-blind, controlled clinical trial.

BACKGROUND AND AIMS: Endothelial dysfunction, insulin resistance and oxidative stress are believed to be central and associated mechanisms in atherogenesis. We aimed to determine the effect of the antioxidant vitamin E on endothelial function, insulin action and cardiovascular risk markers in young healthy adult offspring of parents with Type 2 diabetes. METHODS: Healthy, glucose-tolerant adults (18-38 years), 14 (12 male/2 female) with at least one parent with Type 2 diabetes, and 14 (12 male/2 female) subjects with no family history of diabetes (controls) were studied. Insulin action was assessed by euglycaemic hyperinsulinaemic clamp (1 mU/kg/min). Endothelial function was assessed by forearm blood flow (FBF) responses to intra-brachial artery infusions of acetylcholine (ACh) (endothelium-dependent vasodilation), sodium nitroprusside (SNP) (endothelium-independent vasodilation) and N(G)-monomethyl L-arginine (LNMMA) (nitric oxide synthase inhibition). Thirteen offspring (18-38 years, 11 male/2 female, BMI < 30 kg/m2) completed a randomized, double-blind, crossover trial (12 weeks vitamin E 800 IU/day or placebo, 6-week washout). RESULTS: Exogenous glucose infusion rates to maintain euglycaemia were positively associated with response to acetylcholine in offspring (r = 0.61, P < 0.05), and were linked with triglycerides. Vitamin E had no effect on endothelial function, insulin action or cardiovascular risk markers in healthy adult offspring of parents with Type 2 diabetes. CONCLUSIONS: Our results support a positive association between insulin action and endothelial-dependent vasodilation in young healthy adult offspring of parents with Type 2 diabetes, but indicate no effect of vitamin E on these parameters.

Adolescent↗

A comparison of endothelial function in Caucasian and Chinese women before and after the menopause.

OBJECTIVE: Arterial endothelial dysfunction is a key atherogenic event that may be related to oestrogen status. We therefore aimed to compare menopause-related changes in endothelial physiology in Chinese and Caucasian females. METHODS: We studied 40 female subjects; 20 Chinese from a rural region of Southern China (ten premenopausal, aged 20-35 years, and ten postmenopausal, aged 55-66 years), and 20 age-matched Caucasian females from Sydney, Australia. All women had a clinical history, resting blood pressure and fasting lipids measured, and endothelial function assessed. Using high-resolution external vascular ultrasound, brachial artery diameter was measured at rest, after flow increase (causing endothelium-dependent dilatation) and after sublingual glyceryl trinitrate (GTW) (an endothelium-independent dilator). RESULTS: There was a significant decline in endothelium-dependent dilatation (EDD) comparing Caucasian females from the premenopausal versus postmenopausal groups (8.4+/-2.7% versus 2.7+/-2.9%; P<0.001). In contrast, there was no significant difference in EDD between pre- and postmenopausal Chinese (9.8+/-3.3% versus 8.3+/-1.7%; P=0.22). On multivariate analysis, postmenopausal status was associated with impaired EDD in Caucasian females (P<0.002) independent of serum cholesterol, blood pressure and vessel size. In contrast, EDD in the Chinese females was not significantly influenced by any of these factors. GTW-induced dilatation was also impaired in the older Caucasian females, a finding explained on multivariate analysis by the increased vessel size in this patient group (P=0.03). CONCLUSION: Menopause is associated with impaired arterial endothelial function in Caucasian but not Chinese women. This suggests possible ethnic differences in menopause-related vascular changes.

Adult↗

Supplementations of docosahexaenoic acid and blueberry suppress a high-fat breakfast-induced postprandial inflammation but only docosahexaenoic acid improves endothelial function in healthy adults: a randomized, double-blind, placebo-controlled crossover intervention study.

Blueberries and n - 3 polyunsaturated fatty acids each can provide protection against inflammation and cardiometabolic disorders. However, the underlying mechanisms are not fully understood. We hypothesized that blueberry and docosahexaenoic acid (DHA) can suppress high fat (HF) meal-induced postprandial inflammation and improve endothelial function. Sixty-two healthy participants (age: 26.8 &#xb1; 1.2 y; BMI: 22.1 &#xb1; 1.2 kg/m&#xb2;) consumed an isoenergetic breakfast (850 kcal) containing 34.7 g mostly animal fat (36% kcal), 25.3 g protein, and 111 g carbohydrate, with or without either 42.2 g blueberry powder (BBP) or 1.76 g DHA in a randomized, double-blind, placebo-controlled crossover intervention study. Blood samples were collected before and 1 h, 3 h and 6 h after breakfast. Monocyte activation, proinflammatory gene expression, cytokine production and endothelial function were assessed. Compared with the placebo control, DHA supplementation suppressed the HF breakfast-induced: expression of IL-1&#x3b2; by 21.6% (P < .01) and prostaglandin-endoperoxide synthase 2 (PTGS2, i.e., cyclooxygenase 2) by 22.8% (P < .01) at 6 h; plasma IL-1&#x3b2; production by 40.1 to 49.8% (P < .01) at 1-6 h; lipoprotein lipase (LPL)-treated blood IL-1&#x3b2; production by 40.9% (P < .0001) at 6 h; and total cholesterol/HDL cholesterol ratio by 2.2% (P < .01) at 3 h and 3.5% (P < .0001) at 6 h. BBP supplementation suppressed LPL-treated blood IL-1&#x3b2; production by 23.1% (P < .05) at 6 h. BBP and DHA also induced postprandial increases in reactive hyperemia index (RHI) scores relative to the fasting baselines, with DHA producing a 13.3% increase compared with placebo at 6 h (P < .05). In conclusion, supplementation with BBP or DHA suppressed the HF meal-induced postprandial inflammation but only DHA improved postprandial endothelial function. This study was registered at clinicaltrails.gov (NCT02472171).

Blueberry↗

Fenofibrate and pioglitazone improve endothelial function and reduce arterial stiffness in obese glucose tolerant men.

Obesity is a low grade inflammatory state associated with premature cardiovascular morbidity and mortality. Along with traditional risk factors the measurement of endothelial function, insulin resistance, inflammation and arterial stiffness may contribute to the assessment of cardiovascular risk. We conducted a randomised placebo controlled trial to assess the effects of 12 weeks treatment with a PPAR alpha agonist (fenofibrate) and a PPAR gamma agonist (pioglitazone) on these parameters in obese glucose tolerant men. Arterial stiffness was measured using augmentation index and pulse wave velocity (PWV). E-selectin, VCAM-1 and ICAM-1 were used as markers of endothelial function. Insulin sensitivity improved with pioglitazone treatment (p=0.001) and, in keeping with this, adiponectin increased by 85.2% (p<0.001). Pro-inflammatory cytokine levels (TNFalpha, IL-6 and IL-1 beta) fell with both treatments (p<0.01 for TNFalpha and IL-1 beta, p<0.001 for IL-6). VCAM-1 and ICAM-1 were reduced with both treatments (p<0.001 for VCAM-1, p<0.05 for ICAM-1) and E-selectin improved with pioglitazone treatment (p=0.05). Both treatments resulted in a fall in augmentation index. PWV fell by 17.4% with fenofibrate treatment (p<0.001) and 16.3% with pioglitazone treatment (p<0.001). Pioglitazone and fenofibrate treatment of obese, glucose tolerant men reduces inflammation, improves markers of endothelial function and reduces arterial stiffness. These results suggest that treatment with PPAR agonists has potential to reduce the incidence of premature cardiovascular disease associated with obesity.

Adult↗

Orally and transdermally replaced estradiol improves endothelial function equally in middle-aged women after surgical menopause.

OBJECTIVE: Improvement in endothelial function may be an important mechanism by which estrogen replacement therapy protects postmenopausal women against coronary artery disease. We determined whether the vascular effects of estradiol depend on the route of administration. STUDY DESIGN: Six weeks after surgically induced menopause, 43 healthy women were assigned randomly to 28 weeks of treatment by either orally or transdermally replaced estradiol. Endothelium-dependent and endothelium-independent dilation were calculated with the use of the diameters of the brachial artery that were measured at rest by high resolution ultrasound scanning after reactive hyperemia and after sublingual glyceryl trinitrate. RESULTS: Endothelium-dependent dilation increased after oral estradiol replacement from 6% +/- 3.9% to 13.2% +/- 4.4% (P <.0001) and after transdermal estradiol replacement from 7% +/- 4.9% to 14.9% +/- 5.6%(P <.0001). Endothelium-independent dilation did not change significantly in either group. The improvements in endothelium-dependent dilation after estrogen substitution were independent of the changes in blood lipids and lipoproteins. CONCLUSION: Both oral and transdermal long-term replacement of estradiol lead to improved endothelial function in healthy middle-aged women after surgically induced menopause.

Administration, Cutaneous↗

Hypercholesterolemia does not alter endothelial function in spontaneously hypertensive rats.

In humans, hypercholesterolemia and hypertension are associated with endothelial dysfunction. Here, we assess whether hypercholesterolemia induces endothelial dysfunction in rats with pre-existing hypertension. Spontaneously hypertensive rats (SHR) and normotensive controls (WKY) were fed with a high-cholesterol diet for 12 weeks, and endothelial function was assessed in isolated thoracic aortic rings. In SHR and WKY rats, the hypercholesterolemic diet resulted in the elevation of total cholesterol and low-density lipoprotein levels by approximately 2.5- and 4.5-fold, respectively. However, in aorta, the basal nitric oxide (NO) production--as assessed by the magnitude of L-NG-nitroarginine methyl ester-induced vasoconstriction as well as the NO-dependent relaxation induced by acetylcholine or histamine--were not diminished either in SHR or in WKY rats fed with the hypercholesterolemic diet. Interestingly, prostacyclin (PGI2) production in aortic rings from SHR rats was higher than in the aorta from WKY rats. However, the hypercholesterolemic diet had no further effects on PGI2 production in the aorta either of SHR or WKY rats. The monocyte chemoattractant protein 1 level in plasma was slightly elevated in SHR and WKY rats fed with the hypercholesterolemic diet compared with their normocholesterolemic counterparts. In summary, even in the presence of pre-existing hypertension, hypercholesterolemia fails to modify NO-dependent and PGI2-dependent endothelial function in SHR rats; it also does not induce a robust inflammatory response. Both are prerequisites for the development of atherosclerosis.

Animals↗

Rapid effects of rosiglitazone treatment on endothelial function and inflammatory biomarkers.

BACKGROUND: Antidiabetic thiazolidinediones (TZDs), like rosiglitazone or pioglitazone, improve endothelial function in patients with type 2 diabetes or metabolic syndrome, but it is currently unknown, whether these beneficial effects of TZDs depend on their metabolic action or may be caused by direct effects on the endothelium. Therefore, the present study examined whether short-term rosiglitazone treatment influences endothelium-dependent vasodilation as well as serum levels of vascular disease biomarkers in healthy, nondiabetic subjects. METHODS AND RESULTS: Short-term treatment (21 days) of healthy subjects (n = 10) did not significantly change blood glucose levels or lipid profile. In contrast, rosiglitazone significantly increased flow-mediated, endothelium-dependent vasodilation already within the first day from 5.3+/-2.7% at baseline to 7.8+/-2.6%, further increasing it to 9.4+/-3.0% at day 21. In addition, the early improvement of endothelium-dependent vasodilation was paralleled by a rapid reduction of serum levels of the biomarkers C-reactive protein (CRP), serum amyloid A (SAA), and sE-selectin. Moreover, after drug withdrawal all markers remained suppressed for the whole follow-up period of 7 days. In contrast, rosiglitazone treatment did not significantly affect tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, sICAM-1, sVCAM-1, and sCD40L levels. CONCLUSIONS: Our study suggests a direct effect of TZD treatment on endothelial function and inflammatory biomarkers of arteriosclerosis, promoting the concept that TZDs, independent of their metabolic action, may exhibit protective effects in the vessel wall.

Adult↗

Determinants of arterial nitrate-mediated dilatation in children: role of oxidized low-density lipoprotein, endothelial function, and carotid intima-media thickness.

BACKGROUND: Impaired arterial dilatation response to nitroglycerin has been observed in adults with risk factors for atherosclerosis and in patients with established atherosclerotic disease. This defect parallels changes in vascular endothelial function and may be attributed to increased oxidative stress. Because atherosclerosis begins in childhood, we examined the correlates of nitrate-mediated dilatation (NMD) in children, including brachial artery endothelial function, oxidized LDL, and carotid artery intima-media thickness (IMT). METHODS AND RESULTS: Brachial artery flow-mediated endothelium-dependent dilatation (FMD) and nitrate-mediated smooth muscle function, IMT of the carotid bulb, and brachial artery and oxidized LDL were measured in 142 children (mean age, 11 years; range, 8 to 17 years), including 87 healthy children, 41 diabetic children, and 14 children with familial hypercholesterolemia. NMD correlated directly with FMD (r=0.46, P<0.001) and inversely with brachial artery baseline diameter (r=-0.36, P<0.001), age (r=-0.25, P=0.003), body mass index (r=-0.31, P<0.001), diabetes (r=-0.22, P=0.008), oxidized LDL (r=-0.18, P=0.045), and IMT (r=-0.33, P<0.001). In a multivariate regression model, the significant correlates for NMD were FMD response (beta=0.003, P<0.001), brachial artery diameter (beta=-0.03, P=0.01), oxidized LDL (beta=-0.07, P=0.02), and IMT (beta=-0.15, P=0.03). CONCLUSIONS: Reduced endothelial function, increased oxidative stress, and preclinical carotid atherosclerosis are independent determinants of impaired NMD in children. These data thus suggest that primary nitrate tolerance occurs in children at risk for atherosclerosis.

Adolescent↗