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Results for “Endothelial function”

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At least 613 records · Page 34Linked to original sources

PubMedDate not supplied

Effect of an estrogen/statin combination on biochemical markers of endothelial function in human coronary artery cell cultures.

OBJECTIVE: The combination of an estrogen with a statin for therapy of postmenopausal women is of interest because both substance classes exert beneficial effects on the lipid profile. However, both substance classes also elicit positive direct effects on the vasculature. Therefore in the present in vitro study an estrogen/statin combination was investigated for its effect on biochemical markers of endothelial function. MATERIAL AND METHODS: In endothelial cell cultures from human coronary arteries, the effect of estradiol/fluvastatin, alone and in equimolar combinations, were tested at the concentrations 0.01, 0.1, and 1 microM. The vasodilator prostacyclin, the vasoconstrictor endothelin, endothelial nitric oxide synthase (responsible for synthesis of the vasodilator nitric oxide), the procoagulatory factor plasminogen activator inhibitor-1, and the monocyte chemoattractant protein were chosen as markers. RESULTS: The estradiol/fluvastatin combination was able to increase prostacyclin production (25-100%) in an additive manner. The reduction of endothelin synthesis in the range of 21-46% was higher with the combination than with the monosubstances; the reduction, however, was not statistically significant. The expression of endothelial nitric oxide synthase was not significantly increased by the combination compared with the monosubstances, however, a tendency to an additive increase was observed. For the synthesis of plasminogen activator inhibitor-1, no significant changes were seen for either the monosubstances or the combination. The synthesis of monocyte chemoattractant protein-1 was decreased by the combination between 21% and 40%; the decrease, however, was not statistically significant compared with the effect of the monosubstances. The effective estradiol concentrations are higher than can be achieved by replacement therapy; in contrast, fluvastatin was effective at concentrations that can be reached during clinical treatment. CONCLUSIONS: These results indicate that an estrogen/statin combination exerts beneficial effects on the vasculature that seem to be superior to the effects of the monosubstances. The changes found for the biochemical markers can improve endothelial function. The presented results should encourage the performance of clinical studies in cardiovascular risk patients with estrogen/statin combinations.

Anticholesteremic Agents↗

PubMed2006

Decreased heparin cofactor II activity is associated with impaired endothelial function determined by brachial ultrasonography and predicts cardiovascular events.

BACKGROUND: Heparin cofactor II (HCII) could inactivate thrombin after binding to dermatan sulfate at injured arterial walls, and has been shown to be a novel and independent antiatherosclerotic factor. However, the relation between plasma HCII activity and peripheral vascular endothelial function remains unclear. METHODS: A total of 199 patients (mean age, 63+/-14 years) were enrolled and followed up for a median period of 24 months. Endothelial function was assessed using brachial ultrasonography to determine endothelium dependent flow-mediated vasodilation (FMD). Cox regression analyses were conducted for the 199 subjects, with cardiovascular events being defined as myocardial infarction (MI), percutaneous coronary intervention (PCI), coronary artery bypass grafting (CABG), ischemic stroke, and peripheral artery revascularization. RESULTS: A total of 31 patients (16%) had cardiovascular events. Patients with cardiovascular events had significantly lower HCII activity (112+/-34 versus 127+/-34%, p=0.027) and lower antithrombin III (ATIII) activity (82+/-12 versus 88+/-13%, p=0.014) than those without events. By multivariate analysis, age (p=0.012), hsCRP (p=0.020) and HCII activity (p=0.035) were correlated with FMD. Kaplan-Meier analysis was performed and showed plasma HCII (p=0.036) and ATIII activities (p=0.005) were predictors of cardiovascular events. By Cox regression analysis, plasma HCII activity (p=0.026) could be an independent predictor of future cardiovascular events, but not ATIII. CONCLUSIONS: The present study demonstrates that plasma HCII activity is positively correlated with endothelial vasodilator function. Furthermore, plasma HCII activity could be a predictor of future cardiovascular events in patients with suspected coronary artery disease, suggesting its role in atherosclerosis.

Aged↗

PubMed1997

Physiology and biochemistry of endothelial function in children with chronic renal failure.

Premature atherosclerosis is a major cause of morbidity and mortality in chronic renal failure (CRF). Endothelial dysfunction is a key early event in atherogenesis. The aim of this study was to assess the effect of CRF on endothelial function using physiological and biochemical measures. To focus on the effect of CRF itself, 23 children (matched with 23 controls for age and vessel diameter) were selected because they were normotensive, had normal total cholesterol (TC) levels, and were not on vasoactive drugs. Their mean (range) age was 12.0 (7.8 to 17.0) years; GFR 17.5 (8.8 to 34.5) ml/min/1.73 m2. The physiology of endothelial function in the brachial artery was assessed using high resolution ultrasound by measuring its diameter at rest, during reactive hyperemia (endothelium dependent dilation) and after sublingual glyceryl trinitrate (GTN; endothelium independent dilation). Nitric oxide (NO) metabolites and endogenous NO synthetase (eNOS) inhibitors were measured as an assessment of endothelial metabolism. Brachial artery dilation to flow [FMD, mean (SEM)%] was reduced in CRF to 4.9 (0.6) and controls 8.6 (0.6), P < 0.0001. In contrast, the response to GTN was similar in both groups: CRF 25.1 (1.6), controls 23.3 (1.2), P = 0.31. There was no difference in TC, low density lipoprotein (LDL) or high density lipoprotein (HDL) between the patients and the controls. Triglycerides (TG) were higher in the patients but within the normal range. Antibodies against oxidized LDL (ox-LDL) were high in CRF. Endogenous NOS inhibitors were high in CRF, and intermediate NO metabolites were low. There was no correlation between FMD of the brachial artery and lipid subfractions, or with NO metabolites or eNOS inhibitors. Endothelium dependent dilation of the brachial artery is impaired in children with CRF who do not have co-existing risk factors for atherosclerosis. This may represent early evidence of atherogenic vascular disease.

Adolescent↗

PubMed2005

[Effects of atorvastatin, fluvastatin, pravastatin, and simvastatin on endothelial function, lipid peroxidation, and aortic atherosclerosis in hypercholesterolemic rabbits].

OBJECTIVE: To compare the effects of atorvastatin, fluvastatin, pravastatin, and simvastatin on endothelial function, aortic atherosclerosis, and the content of malondialdehyde (MDA) in native and oxidized LDL and in the arterial wall of hypercholesterolemic rabbits after adjusting the dosages of those statins to reduce total serum cholesterol levels to similar values. METHODS: Male rabbits were divided into the following 6 groups of 10 animals (n=10): 1) GH (control)--hypercholesterolemic animals; 2) GA--atorvastatin; 3) GF--fluvastatin; 4) GP--pravastatin; 5) GS--simvastatin; and 6) GN--normal. The animals were fed a standard food preparation enriched with 0.5% cholesterol and 2% coconut oil for 45 days. Fifteen days after beginning the experiment, atorvastatin, fluvastatin, pravastatin and simvastatin were administered for 15 days through gavage, and the dosages were adjusted to obtain similar cholesterol values in each group. At the end of the experiment, a blood sample was withdrawn for determining total cholesterol and separating the lipoproteins, and a segment of the thoracic aorta was removed to be used for studying endothelial function and lipid peroxidation, and for measuring aortic atherosclerosis in histological sections. RESULTS: The statins significantly reduced total serum cholesterol levels, LDL-cholesterol levels, and aortic atherosclerosis. The MDA content was also significantly reduced in native and oxidized LDL, as well as in the arterial wall. Endothelium-dependent relaxation was significantly greater in the treated group compared with that in the hypercholesterolemic group. CONCLUSION: The statins, at dosages adjusted, had a significant and similar effect in reducing lipid peroxidation in native and oxidized LDL-C and in arterial walls, in decreasing aortic atherosclerosis, and in reverting endothelial dysfunction.

Animals↗

PubMed2004

The role of insulin and the adipocytokines in regulation of vascular endothelial function.

Vascular integrity in the healthy endothelium is maintained through the release of a variety of paracrine factors such as NO (nitric oxide). Endothelial dysfunction, characterized by reduced NO bioavailability, is associated with obesity, insulin resistance and Type II diabetes. Insulin has been demonstrated to have direct effects on the endothelium to increase NO bioavailability. Therefore altered insulin signalling in the endothelium represents a candidate mechanism underlying the association between insulin resistance and endothelial dysfunction. In recent years, it has become apparent that insulin sensitivity is regulated by the adipocytokines, a group of bioactive proteins secreted by adipose tissue. Secretion of adipocytokines is altered in obese individuals and there is increasing evidence that the adipocytokines have direct effects on the vascular endothelium. A number of current antidiabetic strategies have been demonstrated to have beneficial effects on endothelial function and to alter adipocytokine concentrations in addition to their effects on glucose homoeostasis. In this review we will explore the notion that the association between insulin resistance and endothelial dysfunction is accounted for by adipocytokine action on the endothelium. In addition, we examine the effects of weight loss, exercise and antidiabetic drugs on adipocytokine availability and endothelial function.

Adipose Tissue↗

PubMed2002

Insulin resistance, dyslipidaemia, inflammation and endothelial function in nephrotic syndrome.

BACKGROUND: Nephrotic syndrome (NS) is associated with an increased risk of cardiovascular disease (CVD). We have shown previously that endothelial function, measured by post-ischaemic flow-mediated dilatation (FMD) of the brachial artery, is impaired in NS. In this study our aim was to assess the potential roles of insulin resistance, plasma non-esterified fatty acids (NEFAs) and inflammation in endothelial dysfunction in NS patients. METHODS: FMD was compared between NS patients (n=19) and controls (CS, n=19). Plasma glucose, insulin and NEFAs were measured. Insulin resistance was calculated using the Homeostasis Model Assessment (HOMA) score. C-reactive protein (CRP), interleukin-6 (IL-6), tumour necrosis factor alpha (TNFalpha) and fibrinogen were measured as markers of inflammation. RESULTS: FMD was significantly lower in the NS group (mean+/-standard error, NS 5.1+/-0.7%, CS 7.3+/-0.7%, P=0.02). Fasting insulin (NS 12.5+/-1.5 mU/l, CS 6.8+/-0.7 mU/l, P<0.01), fasting glucose (NS 5.3+/-0.2, CS 4.8+/-0.1, P=0.02) and the HOMA score (NS 3.0+/-0.4, CS 1.5+/-0.2, P=0.001) were significantly higher in NS. These differences persisted after adjusting for waist circumference. Of the inflammatory markers, only fibrinogen (P<0.01) and IL-6 (P=0.01) were significantly increased in NS. Despite significantly lower plasma NEFAs in NS, the NEFA:albumin ratio showed a non-significant trend to higher levels in NS (NS 10.7+/-0.1 micro mol/g, CS 8.7+/-0.1 micro mol/g, P=0.06). Within the NS group, multivariate backward regression analysis showed that NEFAs (P<0.01) and low-density lipoprotein (LDL) cholesterol (P=0.05) were significant negative independent predictors of FMD. CONCLUSION: Endothelial function in NS is inversely correlated with plasma concentrations of NEFAs and LDL cholesterol. Dyslipoproteinaemia and NEFAs probably contribute to the increased risk of CVD seen in NS. We also postulate that in NS, hypoalbuminaemia increases the delivery of NEFAs to endothelial cells thereby impairing the synthesis and release of nitric oxide.

Adult↗

PubMed2004

[Effects of C-type natriuretic peptide gene transduction on neointimal hyperplasia and endothelial function after angioplasty].

OBJECTIVE: To investigate the effects of C-type natriuretic peptide (CNP) gene transduction on neointimal hyperplasia and endothelial function after angioplasty. METHODS: Eighty-four rabbits were divided into 3 equal groups, namely normal control group, alkaline phosphatase gene transduction group and CNP gene transduction group. The rabbits in the latter two groups were given high-cholesterol diet 7 d before the experiment, followed by establishment of restenosis models by injuring the iliac artery and the specified gene transfer via retroviral vectors. Those in the normal control group were fed with normal diet. Before high-cholesterol diet and killing respectively, 2 ml venous blood samples were taken for testing blood lipid and serum CNP concentration. In the two groups with gene transduction, the injured rabbit iliac arteries were harvested for ex vivo vascular ring tension test, histological and pathological examinations, as well as immunohistochemistry analysis of CNP. The lumen area, neointimal thickness, neointimal area, ratio of intimal to medial area were measured by image analysis system. RESULTS: There were no significant differences in blood lipid and serum CNP concentration between the two gene transduction groups at the same time points both before and after operation. In CNP gene transduction group, endothelium-dependent relaxation of the vascular rings was significantly improved in comparison with the other two groups (P<0.01), irrespective of L-Arg pretreatment, whereas endothelium-independent relaxation function varied little between the 3 groups (P>0.05). Poor relaxation function to Ach of the vascular rings was resulted after pretreatment with LMMA. CNP gene expression at the site of gene transfer was detected in the CNP gene transduction group and in 2 weeks after balloon injury, the neointimal thickness, neointimal area and ratio of the neointimal to tunica media area were markedly increased in the two gene transduction groups, but the measurements were significantly lower in CNP group (P<0.01). CONCLUSION: CNP gene can be successfully transferred and effectively expressed at the injured site in the blood vessels to decrease the hyperplasia and significantly improve endothelial function after angioplasty.

Angioplasty, Balloon↗

PubMed1999

Endothelial function and atherosclerosis.

Under normal conditions, the vascular endothelium exerts vasodilator, antithrombotic, and growth-inhibiting effects on the vessel wall. In the setting of atherosclerosis, endothelial dysfunction contributes to vasoconstriction, thrombosis, and growth of vascular smooth muscle. This article reviews the important contributors to endothelial function both in health and in the diseased state of atherosclerosis. Therapeutic options for improvement of endothelial function will also be summarized.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2006

Anti-tumour necrosis factor-alpha therapy over conventional therapy improves endothelial function in adults with rheumatoid arthritis.

Rheumatoid arthritis (RA) is associated with cardiovascular morbidity and mortality and inflammation contributes to related endothelial dysfunction. We aimed to investigate the effect of anti-TNFalpha therapy on endothelial function in subjects with rheumatoid arthritis. We measured flow-mediated (FMD) and GTN-mediated dilation of the brachial artery before and following 36 weeks of anti-TNFalpha therapy in nine RA patients and in a group of RA patients on conventional therapy. Thirty-six weeks of anti-TNFalpha therapy improved FMD relative to those on conventional therapy (8.65 +/- 1.50 vs. 1.70 +/- 1.36%, P = 0.02). No significant changes in GTN responses were evident. Significant improvements in tender (P = 0.03) and swollen (P = 0.02) joint counts, patients' global self-assessment (P = 0.01) and DAS-28 scores (P = 0.04) were observed in the anti-TNFalpha treated group. The addition of anti-TNFalpha treatment to conventional therapy, in those with severe RA, reduces inflammatory symptoms and improves endothelial function, potentially lowering future atherosclerotic risk.

Adult↗

PubMed1985

Reticulo-endothelial function in rats with obstructive jaundice.

Reticulo-endothelial function was evaluated by measuring the biokinetics of a standardized 99mTc-sulphur colloid using scintillation camera technique in rats with biliary obstruction. There was no difference in the uptake of the colloid in the liver (K1) between sham operation and biliary obstruction at 1 week and 3 weeks. However, when corrected for changes in liver volume, the corrected colloidal uptake rate (cK1) of the liver was significantly decreased in 1 week's biliary obstruction (P less than 0.005 compared with sham operation) and 3 weeks' biliary obstruction (P less than 0.025 compared with 1 week obstruction). Colloidal uptake rate of the extrahepatic reticulo-endothelial system (K2) was significantly increased (P less than 0.005) in rats with 3 weeks' biliary obstruction. Activity distribution of 99mTc-sulphur colloid in 3 weeks' biliary obstruction was significantly decreased in both total organ basis and per gram basis (P less than 0.005). The results demonstrated a depression of RE activity of the liver in biliary obstruction.

Animals↗

PubMed2005

Endothelial function in conduit and resistance arteries in men with coronary disease.

The aims of this study were to determine whether non-invasive measurement of endothelial function in conduit arteries reflects that of subcutaneous resistance arteries measured in vitro and to examine whether there is an endothelial dysfunction also in resistance arteries in patients with a previous myocardial infarction. The brachial artery diameter responses to a hyperemic flow stimulus and an in vitro method, pressure myography, to directly evaluate flow-mediated responses in arteries obtained from biopsies of subcutaneous fat were measured in 25 patients with a previous myocardial infarction and in 8 aged matched healthy subjects. Flow-mediated dilatation of the brachial artery was more pronounced in the healthy group compared with the group with coronary disease, 5.1 +/- 2.5% and 2.6 +/- 2.1%, respectively (p < 0.05). The flow-mediated dilatation in subcutaneous arteries from CHD patients was significantly reduced compared to control subjects (e.g. percent change from initial preconstriction at maximum flow rate of 204 microl/min: 42 +/- 7% CHD (n = 25) versus 84 +/- 24% control (n = 8), ANOVA, p = 0.03). There was a significant correlation between flow-mediated dilatation of the brachial artery and maximum flow-mediated dilatation at microvascular level, (p < 0.01). In conclusion this study demonstrates endothelial dysfunction in both conduit and resistance circulation in patients after myocardial infarction compared to an aged-matched healthy control group. Furthermore, a significant and independent relationship between endothelial function by means of flow-mediated dilatation in large conduit arteries and resistance arteries was observed.

Adult↗

PubMed2002

Endothelial function in the post-prandial state.

In recent years the endothelium has emerged as an important protective barrier against the development of atherosclerosis. Endothelial dysfunction, often characterised by impaired endothelium-dependent vasodilation, is generally considered to be an early marker of cardiovascular disease. Recently, it has been noted that the post-prandial state is associated with impaired endothelium-dependent vasodilation. Since man lives in a post-prandial state most of the day, prolonged exposure to dietary factors which impair endothelial function or delayed post-prandial recovery of the endothelium could negatively affect the cardiovascular risk profile. This review will focus on post-prandial endothelial function characterised by endothelium-dependent changes in vasomotion.

Cardiovascular Diseases↗

PubMed1998

Distinct associations of HbA1c and the urinary excretion of pentosidine, an advanced glycosylation end-product, with markers of endothelial function in insulin-dependent diabetes mellitus.

Dysfunction of the vascular endothelium is considered an early step in the development of diabetic angiopathy. Hyperglycaemia results in endothelial dysfunction, both through direct effects of glucose and through formation of advanced glycosylation end-products (AGEs). We hypothesized that the effects of glucose and AGEs on endothelial function in insulin-dependent diabetes mellitus (IDDM) are distinct and are reflected by distinct plasma markers of endothelial function. We therefore measured plasma levels of von Willebrand factor (vWF), soluble (s) E-selectin and vascular cell adhesion molecule-1 (sVCAM-1), and evaluated the relationship with HbA1c and urinary excretion of pentosidine, an AGE product, in 56 patients with IDDM. Urinary pentosidine excretion was higher in the diabetic than in a control group (n = 60) of similar age (P < 0.0001) and showed a steeper increase with age (P < 0.02 vs controls). In the diabetic group, sE-selectin was correlated to HbA1c (r = 0.52, P < 0.0001), whereas sVCAM-1 was not (r = 0.11, P = 0.47). In contrast, sVCAM-1 showed a trend towards a correlation with log (pentosidine excretion) (r = 0.27, P = 0.06), whereas sE-selectin did not (r = -0.16, P = 0.27). Log(vWF) was correlated to HbA1c (r = 0.50, P < 0.0001) and tended to correlate with log (pentosidine excretion) (r = 0.25, P = 0.07). Multivariate analyses with both pentosidine and HbA1c as independent variables showed significant associations of sE-selectin with HbA1c, of sVCAM-1 with pentosidine, and of log(vWF) with both HbA1c and pentosidine (all P-values < 0.02). Our results imply that the effects of glucose and AGEs on the endothelium can be reflected by distinct endothelial markers. Plasma sE-selectin may reflect short-term effects of glucose on the endothelium, sVCAM-1 the effects of AGEs, and vWF the combined effect of glucose and AGEs.

Adult↗

PubMed2001

Improvement of endothelial function in insulin-resistant carotid arteries treated with pravastatin.

OBJECT: Insulin resistance and hypertension are independent risk factors for stroke. Endothelial dysfunction in response to risk factors and carotid artery (CA) disease are important in the pathogenesis of stroke. Pravastatin may have cholesterol-independent pleiotropic effects. In the present study the authors examined the effects of short-course pravastatin treatment on endothelial function in CAs obtained in control and insulin-resistant rats with fructose-induced hypertension. METHODS: Thirty rats were divided into two experimental groups, in which 14 were fed a regular diet and 16 were fed a fructose-enriched diet for 3 weeks. The rats were then divided into four groups: control, pravastatin-treated control, fructose-fed, and pravastatin-treated fructose-fed. Pravastatin was administered (20 mg/kg/day) for 2 weeks. Excretion of the urinary nitric oxide (NO) metabolite nitrite (NO2-) was also assayed. The CAs from all rats were subsequently removed and assessed for endothelium-dependent and -independent vascular reactivity in vitro. The rats in the fructose-fed group were insulin resistant, hyperinsulinemic, and hypertensive relative to the rats in the control and pravastatin-treated control groups and exhibited diminished endothelium-dependent vasomotion and urinary NO2- excretion (p < 0.05), with preserved endothelium-independent vasomotion. Strikingly, pravastatin treatment restored endothelium-dependent vasomotion and urinary NO2- excretion in rats in the fructose-fed pravastatin-treated relative to the fructose-fed group (p < 0.05). CONCLUSIONS: The authors report, for the first time, that pravastatin restores endothelial function in CAs from insulin-resistant rats with fructose-induced hypertension. These beneficial effects were ascribed to direct, cholesterol-independent vascular effects of pravastatin and are likely the result of augmentation of NO production. These data provide impetus for further investigation of nonlipid-lowering indications for pravastatin therapy in the prevention and treatment of CA disease.

Animals↗

PubMed2002

[Effect of atorvastatin on endothelial function in patients with familial hypercholesterolemia].

AIM: To study the influence of treatment with HMG-CoA reductase inhibitor atorvastatin on endothelial function in patients with familial hypercholesterolemia type IIa. MATERIALS AND METHODS: Sixteen patients (5m/11w, 51-/+3 years) with familial hypercholesterolemia were studied before and after 3 months of therapy with atorvastatin 20 mg/day. EDRF release test (D.Celermajer, 1992) was used to assess flow-mediated endothelium-dependent vasodilatation (FMD) of the brachial artery in response to reactive hyperemia. Plasma nitrite/nitrate (NOx) levels were measured as an indirect index of nitric oxide (NO) production in vivo using HPLC. RESULTS: Atorvastatin treatment resulted in a 32% reduction in total serum cholesterol (CH), 41% reduction in low density lipoprotein (LDL) CH, 16% reduction in triglycerides and a 21% increase in high density lipoprotein CH. Flow mediated dilatation (FMD) was impaired at baseline (5.8-/+0.9%) and significantly improved up to 9.5-/+0.9% after 3 month atorvastatin therapy (p<0.002). Change in FMD inversely correlated with baseline FMD (r = -0.58, p<0.05). There was no significant correlation between FMD and neither total serum CH nor LDL CH levels at baseline. During atorvastatin therapy significant reduction of plasma NOx levels occurred from 53.4-/+5.1 mcmol/l at baseline (range 42.6-86.2 mcmol/l) to 35.5-/+5.1 mcmol/l (18.4-46.0 mcmol/l) after treatment (p<0.02, n=7). CONCLUSION: In patients with familial hypercholesterolemia atorvastatin produced beneficial effect on endothelial function (increase in flow-mediated dilatation, decrease in NOx).

Adult↗

PubMed2000

Normal endothelial cell function.

Endothelial cell functions, primarily involving regulated mediator secretion or altered surface protein expression, are vital for normal homeostasis. Endothelial cells secrete the potent vasodilator and anti-platelet agent prostacyclin and nitric oxide, and also the potent vasoconstrictor peptide endothelin-1; they control the selective adhesion and emigration of leukocytes from the bloodstream; and they are the source of circulating von Willebrand factor, tissue plasminogen activator and type 1 plasminogen activator inhibitor. The properties of healthy endothelium ensure that an antithrombotic and anticoagulant balance is maintained in the bloodstream, and provide a tonic vasodilator action that controls blood flow and pressure on a minute-to-minute basis. Disturbances of normal endothelial function are strongly implicated in the pathogenesis of atherosclerosis and autoimmune vasculitic diseases including lupus.

Arteriosclerosis↗

PubMed1996

Mechanisms of protection afforded by preconditioning to endothelial function against ischemic injury.

The aim of this study was to assess whether the cardioprotective effect of ischemic preconditioning (IPC) on endothelial function in resistance coronary arteries of the rat involves adenosine and/or activation of ATP-sensitive K+ channels (KATP channels). Isolated rat hearts perfused under constant-flow conditions were exposed to 30 min of partial ischemia (flow rate 1 ml/min) followed by 20 min of reperfusion. Preconditioning was performed with 5 min of ischemia and 10 min of reperfusion before the 30-min ischemia. After the 20-min reperfusion period, coronary arteries were precontracted with U-46619 (0.1 microM), and the coronary response to the endothelium-dependent vasodilator serotonin (5-HT; 10 microM) was compared with that of the endothelium-independent vasodilator sodium nitroprusside (SNP; 3 microM). KATP channels or adenosine receptors were blocked with perfusion of either glibenclamide (0.3 microM) or 8-phenyltheophylline (8-PT; 5 microM), respectively, starting 15 min before IPC or a corresponding sham period. In untreated hearts, ischemia selectively diminished 5-HT-induced vasodilation, compared with sham hearts (without ischemia). The vasodilation by SNP was unaffected after ischemia and reperfusion. Preconditioning in untreated hearts preserved the vasodilation produced by 5-HT. Treatment of hearts with either glibenclamide or 8-PT halved the vasodilation produced by both 5-HT and SNP in sham hearts. Glibenclamide reduced by one-half, whereas 8-PT completely blocked, the protective effect of IPC on endothelium-dependent vasodilation. These results suggest that IPC affords protection to endothelial function in resistance coronary arteries of the rat partially by activation of KATP channels. Adenosine plays a major role in that protection.

Adenosine Triphosphate↗

PubMed2005

Lipid-independent effects of statins on endothelial function and bioavailability of nitric oxide in hypercholesterolemic patients.

BACKGROUND: Experimental evidence suggests a lipid-independent effect of statins on endothelial function and nitric oxide (NO) availability in humans. We investigated whether improvement in NO availability in hypercholesterolemia can be achieved rapidly with statins before lipid-lowering therapy is complete. METHODS: We studied 41 patients (52 +/- 11 years) with low-density lipoprotein (LDL) cholesterol > or = 130 mg/dL (179 +/- 45 mg/dL) randomly assigned to treatment either with atorvastatin (20 mg/day) or cerivastatin (0.4 mg/day). Endothelium-dependent vasodilation of the forearm vasculature was measured by plethysmography and intra-arterial infusion of acetylcholine (ACh) after 3 days (n = 18) and 14 days (n = 39) of treatment. NO availability and oxidative stress were assessed by coinfusion of l-NMMA and vitamin C. RESULTS: After 3 days of treatment, LDL-cholesterol decreased by 11.9% with a further decrease to 29.6% after 14 days ( P < .001). Endothelium-dependent vasodilation improved by +46.7% after 3 days of statin therapy compared with before therapy (ACh 48 microg/min: +15.7 +/- 10.6 vs +10.7 +/- 10.8 mL/min per 100 mL, P < .05). No further improvement in endothelium-dependent vasodilation (+42.7% compared with before therapy) could be demonstrated after 14 days of treatment (ACh 48 microg/min: +17.7 +/- 10.3 vs +12.4 +/- 9.3 mL/min per 100 mL before therapy, P < .001). Coinfusion of ACh plus vitamin C was able to improve endothelium-dependent vasodilation before but not after 3 or 14 days of statin therapy either. The improvement in endothelium-dependent vasodilation after therapy was no longer observed when the NO-synthase inhibitor l-NMMA was coinfused together with ACh. CONCLUSIONS: Short-term lipid-lowering therapy with statins is able to improve endothelial function and NO availability almost completely after 3 days in hypercholesterolemic patients probably by decreasing oxidative stress. This improvement seems to be more rapid than the accompanying decline in LDL-cholesterol and not related to these lipid changes. This finding can support the concept of lipid-independent effects of statins in humans.

Acetylcholine↗