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Folic acid improves endothelial dysfunction in type 2 diabetes--an effect independent of homocysteine-lowering.

Diabetes is associated with endothelial dysfunction, which in part may be related to uncoupling of the endothelial nitric oxide (NO) synthase enzyme, thus reducing the availability of NO. As folates may potentially reverse the uncoupling of NO synthase, we wanted to determine whether folic acid supplementation could modulate endothelial function and markers of inflammation in patients with type 2 diabetes without vascular disease. Nineteen patients with type 2 diabetes were treated with folic acid (10mg/day for 2 weeks) versus placebo in a randomized, placebo-controlled, cross-over study with an 8-week washout period between treatments. Fasting endothelium-dependent flow-mediated dilatation (FMD) of the brachial artery, endothelium-independent nitroglycerin-mediated dilatation (NMD), plasma homocysteine, serum lipids, folate, and inflammatory markers (high-sensitivity C-reactive protein, soluble intercellular adhesion molecule-1 and vascular cell adhesion molecule-1, interleukin-18, tumor necrosis factor-alpha) were assessed after each 2-week treatment period. Folic acid supplementation significantly increased folate levels and lowered plasma homocysteine levels. Folic acid significantly improved FMD compared to placebo (5.8 +/- 4.8% vs 3.2 +/- 2.7%, p = 0.02). There were no significant effects of folic acid supplementation on lipids, NMD, or the inflammatory markers. There was no relationship between the change in homocysteine and the improvement in FMD. Thus, 2 weeks of folic acid supplementation can improve endothelial dysfunction in type 2 diabetics independent of homocysteine-lowering, but does not modulate markers of inflammation.

Brachial Artery↗

Endothelial dysfunction: from physiology to therapy.

The endothelium controls the tone of the underlying vascular smooth muscle mainly through the production of vasodilator mediators. In some cases, this function is hampered by the release of constrictor substances. The endothelial mediators are also involved in the regulation by the endothelium of vascular architecture and the blood cell-vascular wall interactions. The endothelium-derived factors comprise nitric oxide (NO), prostacyclin, and a still unknown endothelium-derived hyperpolarizing factor(s) (EDHF). In most vascular diseases, the vasodilator function of the endothelium is attenuated. In advanced atherosclerotic lesions, endothelium-dependent vasodilatation may even be abolished. Various degrees and forms of endothelial dysfunction exist, including (1) the impairment of Galphai proteins, (2) less release of NO, prostacyclin and/or EDHF, (3) increased release of endoperoxides, (4) increased production of reactive oxygen species, (5) increased generation of endothelin-1, and (6) decreased sensitivity of the vascular smooth muscle to NO, prostacyclin and/or EDHF. The levels of bradykinin and angiotensin II within the vascular wall are controlled by angiotensin-converting enzyme (ACE). ACE degrades bradykinin and generates angiotensin II. Bradykinin stimulates endothelial cells to release vasodilators. The actions of the kinin are maintained despite endothelial dysfunction, except in very severe arterial lesions. Angiotensin II may be in part responsible for endothelial dysfunction because it induces resistance to the vasodilator action of NO. Thus, impairment of the generation of angiotensin II blocks the direct and indirect vasoconstrictor effect of the peptide. By potentiating bradykinin, ACE inhibitors promote the release of relaxing vasodilator mediators to restore vasodilator function, and to prevent platelet aggregation as well as the recruitment of leukocytes to the vascular wall.

Aging↗

Increased myocardial ischemia after food is not explained by endothelial dysfunction.

BACKGROUND: Recent studies suggest that a high-fat meal can impair endothelial function. The aim of this study was to determine whether greater myocardial ischemia after either a low-fat or a high-fat meal is associated with an increase in brachial artery endothelial dysfunction. METHODS: Twenty subjects with coronary artery disease and > or =1-mm ST-segment depression during exercise were studied. In a randomized, double-blind, crossover design, ST-segment changes during treadmill exercise and brachial artery diameter and flow-mediated dilation were measured before and 3 hours after a low-fat milkshake meal or the same meal supplemented with 64 grams of cooked fat. RESULTS: After the low-fat but not the high-fat meal, resting brachial artery diameter decreased (before meal 4.72 +/-0.50 mm, after low fat meal 4.62 +/-0.49 mm, P =.001; after high fat meal 4.70 +/-0.51 mm, not significant). High-flow brachial artery diameter was similar before (4.81 +/- 0.48 mm) and after the low-fat (4.82 +/- 0.48 mm) and high-fat (4.84 +/- 0.48 mm) meals (P >.05 for all). Brachial artery flow-mediated dilation was not impaired after either meal. Exercise duration decreased more after the low-fat meal (mean change 39 seconds, 95% CI -14 to -63 seconds, P =.004) than after the high-fat meal (-7 seconds, 95% CI +19 to -34 seconds, not significant). ST-segment depression during equivalent exercise was greater after compared with before both meals (before meals 1.03 +/- 0.69 mm, after low fat 1.27 +/- 0.80 mm, P =.03; after high fat 1.24 +/- 0.74 mm, P =.04). CONCLUSIONS: Increased myocardial ischemia after food is caused by mechanisms other than endothelial dysfunction and by meal components other than cooked fat.

Adult↗

Endothelial dysfunction in patients with coronary artery disease: a comparison of three frequently reported tests.

BACKGROUND: Endothelial dysfunction is useful in predicting future cardiovascular disease. At present several tests are available to test endothelial function: coronary diameter response to acetylcholine, forearm bloodflow (FBF) response to acetylcholine, and brachial artery flow-mediated dilative (FMD) response to postischemic hyperemia. This study aimed to compare the three most frequently reported endothelial function tests. METHODS: Twenty-eight patients (19 males and nine females, mean age 57 years) referred for diagnostic coronary angiography were considered for endothelial function measurement in the coronary artery as well as in the forearm by FBF and FMD. RESULTS: Acetylcholine decreased the mean coronary diameter by 7.4% (SD 6.3%) and increased the mean FBF by 230% (SD 152%). Hyperemia increased the mean brachial diameter by 6.7% (SD 4.8%). The effect of acetylcholine on forearm resistance vessels was significantly related to the effect of acetylcholine on the coronary conduit vessels (P=0.039). Nonetheless, FMD was not related to FBF nor to the coronary response. CONCLUSION: In patients with mild coronary endothelial dysfunction, forearm vasoreactivity is related to the coronary response, provided that the same stimulus is used.

Acetylcholine↗

Interrelationship of free oxygen radicals and endothelial dysfunction--modulation by statins.

3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) are successfully used for the treatment of hypercholesterolemia and profoundly reduce cardiovascular morbidity and mortality in hypercholesterolemic patients. Endothelial dysfunction is the early state of atherosclerosis and predicts adverse cardiac events and mortality. Reduced nitric oxide (NO) bioactivity in the vascular wall, caused by increased free oxygen-radical generation and decreased NO production, seems to be an important underlying mechanism. It is well established that statins improve endothelial dysfunction in hypercholesterolemic patients. However, results from in vitro studies, animal experiments, and small clinical trials suggest that statins may improve vascular function after short-term treatment in hyper- and normocholesterolemic individuals. The underlying mechanisms may at least in part be related to the cholesterol-independent effects of statins on vascular cells. Cellular antioxidative properties of statins, leading to decreased oxidative stress and restoration of NO bioactivity, may be of special relevance for the improvement of vascular function. However, further studies and clinical intervention trials are required to clarify the clinical importance of the pleiotropic effects in humans and their contribution to the well-established clinical benefits of statins and to confirm a beneficial effect of statin therapy on endothelial dysfunction and cardiovascular events in normocholesterolemic patients.

Animals↗

The anti-cancer drug, doxorubicin, causes oxidant stress-induced endothelial dysfunction.

The anticancer drug doxorubicin (DOX) is toxic to target cells, but also causes endothelial dysfunction and edema, secondary to oxidative stress in the vascular wall. Thus, the mechanism of action of this drug may involve chemotoxicity to both cancer cells and to the endothelium. Indeed, we found that the permeability of monolayers of bovine pulmonary artery endothelial cells (BPAEC) to albumin was increased by approximately 10-fold above control, following 24-h exposure to clinically relevant concentrations of DOX (up to 1 microM). DOX also caused >4-fold increases in lactate dehydrogenase leakage and large decreases in ATP and reduced glutathione (GSH) in BPAECs, which paralleled the increases in endothelial permeability. A large part of the ATP loss could be attributed to DOX-induced hydrogen peroxide production which inhibited key thiol-enzymes, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and glucose-6-phosphate dehydrogenase (G6PDH). Depletion of reduced nicotinamide adenine dinucleotide phosphate (NADPH) appeared to be a major factor leading to DOX-induced GSH depletion. At low concentrations, the sulfhydryl reagent, iodoacetate (IA), inhibited GAPDH, caused a decrease in ATP and increased permeability, without inhibiting G6PDH or decreasing GSH. These results, coupled with those of previous work on a related quinone, menadione, suggest that depletion of either GSH or ATP may lead independently to endothelial dysfunction during chemotherapy, contributing to the cardiotoxicity and other systemic side-effects of the drug.

Adenosine Triphosphate↗

Lack of association between Chlamydia Pneumoniae serology and endothelial dysfunction of coronary arteries.

BACKGROUND: Recent publications brought up the hypothesis that an infection with Chlamydia Pneumoniae (CP) might be a major cause of coronary artery disease (CAD). Therefore, we investigated whether endothelial dysfunction (ED) as a precursor of atherosclerosis might be detectable in patients with previous infection with CP but without angiographic evidence of CAD. METHODS: We included 16 patients (6 male / 10 female) of 52 consecutive patients with normal coronary angiography who had typical angina pectoris and pathologic findings in the stress test. Exclusion criteria were: active smoker, elevated cholesterol, hypertension, age > 65 years, diabetes mellitus, treatment with ACE-inhibitors, or known CAD. Blood sample analysis for serum titer against CP (aCP-IgG) was performed after coronary angiography. We looked for endothelial dysfunction analyzing the diameter of the left anterior descending coronary artery (LAD) before and after acetylcholine (ACh) i. c. Quantitative analysis of luminal diameter (LD) was performed in at least two planes during baseline conditions and after ACh for 2 minutes in dosages of 7.2 microg/min and 36 microg/min with an infusion speed of 2 ml/min. Using Doppler guide wire, the coronary flow velocity was measured continuously in the LAD. The coronary flow velocity reserve (CFVR) was measured after 20 microg adenosine i. c. RESULTS: 10 patients had an elevated aCP-IgG (> 1:8). 6 patients with negative titers (aCP-IgG <or= 1:8) served as control (CTRL). Both groups were comparable in age, gender, angina class, results of non-invasive stress-test and the baseline values of LD and flow. In the CP positive group 3 patients (30%) did not show an increase of LD after ACh as evidence of ED. In the CTRL group 4 patients (67 %) had ED. There was no association between aCP-IgG and changes of coronary blood flow after ACh. All patients showed normal CFVR (3.0 +/- 0.27) irrespective of their aCP-IgG values. CONCLUSION: In patients with typical symptoms of coronary ischemia but without angiographically visible CAD and absence of other factors affecting the endothelial function, a previous infection with CP is not associated with endothelial dysfunction.

Adult↗

Treatment with acarbose may improve endothelial dysfunction in streptozotocin-induced diabetic rats.

We sought to determine whether a single reduction of hyperglycemia and those derivatives from nonenzymatic protein glycosylation may be effective in reducing the development of diabetic endothelial dysfunction. Therefore, we investigated how acarbose, an inhibitor of intestinal alpha-glucosidase that reduce hyperglycemia by lowering glucose absorption, may prevent the impairment of acetylcholine (ACh)-induced endothelium-dependent relaxations observed in isolated vascular segments from untreated streptozotocin-induced diabetic rats. When administered after diabetes induction, 10 mg/kg acarbose decreased modestly the enhancement of blood glucose and glycosylated hemoglobin (HbA1c) levels, but not those of advanced glycosylation end products (AGEs). This effect was linked to a partial improvement of ACh-induced responses both in conductance vessels, such as aortic segments, and resistance vasculature, like mesenteric microvessels. When acarbose was introduced after 6 weeks of untreated diabetes, blood glucose, HbA1c, and AGE levels were not affected and endothelial dysfunction remained unchanged in mesenteric microvessels, whereas a small improvement was observed in aortic segments. The addition of 100 U/ml superoxide dismutase enhanced the impaired relaxations to values similar to vessels from nondiabetic rats, indicating a main role for superoxide anions in diabetes-induced endothelial dysfunction. We conclude that hyperglycemia itself or elevated HbA1c, but not plasma AGEs, are related to enhanced oxidative stress and to the impairment of endothelium function associated to diabetes. This process can be partially prevented by reducing glucose absorption with acarbose.

Acarbose↗

Shear stress abnormalities contribute to endothelial dysfunction in hypertension but not in type II diabetes.

BACKGROUND: The relative contribution of the various hemodynamic and metabolic mechanisms leading to endothelial dysfunction may be different in specific vascular diseases. Since shear stress is one of the main mechanical stimuli of endothelial cells, the aim of this study was to investigate its contribution to endothelial dysfunction in two distinct vascular diseases, hypertension and type II diabetes. SUBJECTS AND METHODS: We measured the radial artery diameter at baseline, after ischemic vasodilation and after nitroglycerin vasodilation in 16 untreated patients with high blood pressure, in 15 type II normotensive diabetic patients and in 17 healthy controls. Wall shear stress was evaluated by simultaneous measurements of whole blood viscosity and blood flow velocity. RESULTS: In diabetic patients, whole blood viscosity was significantly higher whereas wall shear stress was similar compared to controls. In hypertensive patients, whole blood viscosity was higher and wall shear stress was lower than in controls. Endothelium-dependent vasodilation was impaired in both hypertensive and diabetic patients (P < 0.01) after adjustment for age, sex, body mass index and postnitroglycerin vasodilation. When adjustments were made for maximal systolic shear stress, endothelium-dependent vasodilation remained lower in the diabetic patients (P < 0.01), but not in those with high blood pressure compared to controls. CONCLUSIONS: In hypertension, endothelium-dependent vasodilation is mainly due to a chronic decrease in shear stress (the most important physiological stimulus of the endothelial cells) with no major intrinsic endothelial cell dysfunction. In contrast, in diabetics, the lower endothelium-dependent vasodilation was not the result of an altered shear stress.

Adult↗

Physical inactivity causes endothelial dysfunction in healthy young mice.

OBJECTIVES: We sought to determine if physical inactivity affects endothelial function in young healthy individuals. BACKGROUND: Recent studies have linked exercise training to increased bioavailability of vascular nitric oxide (NO) and to improved endothelial function in patients with cardiovascular disorders. The effects of physical inactivity on normal vascular endothelial function are not known. METHODS: Healthy young male C57Bl/6 mice living in groups of five in large cages, where they were running, climbing, and fighting during their active cycle, were randomly assigned to stay there or to live alone in small cages where they were predominantly resting. After five and nine weeks citrate synthase activity (a measure of mitochondrial respiratory chain activity), heart weight/body weight ratio, vascular reactivity, and protein expression of endothelial nitric oxide synthase (eNOS) were assessed. RESULTS: Singularized mice showed a reduction of citrate synthase activity (p < 0.05), of endothelium-dependent vasorelaxation (to 65 +/- 5% of control levels; p < 0.001), and of eNOS protein expression (to 53 +/- 8% of control levels; p < 0.01). In striking contrast, vascular responses to potassium chloride, phenylephrine, and the NO-donor racemic S-nitroso-N-acetylpenicillamine were unchanged. The alterations of vascular eNOS-activity were completely reversible when singularized mice underwent exercise. In mice living in groups, exercise showed only a small effect on aortic eNOS expression. CONCLUSIONS: In young healthy individuals physical inactivity induces endothelial dysfunction, which is completely reversible by a short period of moderate exercise training. We suggest that physical inactivity, the so-called sedentary lifestyle, increases cardiovascular risk in young healthy individuals by inducing endothelial dysfunction.

Acetylcholine↗

[Coronary endothelial dysfunction and graft atheromatosis following heart transplantation].

Graft atheromatosis is the most important limiting factor on long-term survival after heart transplantation. Histologically it involves so-called myointimal proliferation occurring in either circumscribed or diffuse form. Endothelial dysfunction with impaired release of nitric oxide represents an early stage of graft atheromatosis. Progression of the disease typically leads to a diffuse narrowing of the coronary tree; however, focal stenoses may also occur. Endothelial dysfunction results in a decrease in physiological coronary flow reserve during exercise, whereas pharmacological flow reserve after papaverine or adenosine administration is maintained. This functional disturbance can be enhanced by transplantation-related (e.g., vascular graft rejections, cytomegalovirus infections, etc.) as well as by cardiovascular risk factors (e.g., hypercholesterolemia, hypertension). The occurrence of endothelial dysfunction and graft atheromatosis may be delayed, although probably not prevented, by elimination of risk factors and optimization of immunosuppressive treatment. Preliminary data suggest that long-term administration of the calcium-antagonist diltiazem may have a protective effect.

Coronary Artery Disease↗

Southwestern Internal Medicine Conference: endothelial dysfunction and vascular disease.

Vascular endothelial cells, critically situated at the blood-tissue interface, exert important effects on vascular tone and permeability, regulate the coagulation and fibrinolytic systems, mediate translocation of inflammatory cells to the tissue compartment, and modulate proliferation of vascular smooth muscle cells. As the physiology of the endothelium has been defined, defects in endothelial function have been identified in association with human disease, and a syndrome of dysfunctional endothelium has been described. Although it remains debatable whether a coherent syndrome of endothelial dysfunction exists, disordered endothelial biology appears to contribute to the pathophysiology of human vascular disease. Identification of specific molecular mechanisms offers potential targets for novel therapeutic interventions, including genetic modification of endothelial cells in vivo.

Blood Coagulation↗

Endothelial dysfunction in a primate model of cerebral vasospasm.

OBJECT: Although abnormalities in the control of endothelial vasomotility have been reported in both experimental and clinical studies, the mechanism of the endothelial dysfunction that occurs following subarachnoid hemorrhage (SAH) remains unclear. Because of the absence of previous in vivo studies of endothelial function in cerebral vessels in response to SAH or cerebral vasospasm, the authors investigated endothelium-dependent responses in an established primate model of vasospasm after SAH. Endothelial function was assessed by examining vascular responses to intracarotid injections of various drugs known to act via the endothelium. Drugs that have a rapid total body clearance were selected so that their pharmacological effects would be limited to the cerebral circulation after an intracarotid infusion. METHODS: Seventeen adult male cynomolgus monkeys were used. Cerebrovascular endothelium-dependent responses were examined in control animals and in animals with SAH 7, 14, and 21 days after placement of a subarachnoid clot around the right middle cerebral artery. Cortical cerebral blood flow (CBF) and cerebrovascular resistance (CVR) were recorded continuously during 5-minute intracarotid infusions of 5% dextrose vehicle, acetylcholine, histamine, bradykinin, or Calcimycin. In control animals the intracarotid infusion of acetylcholine produced a significant (7.8 +/- 9.5%) increase in CBF and a 9.3 +/- 8.7% reduction in CVR in comparison with a control infusion of dextrose vehicle. The responses to acetylcholine disappeared in animals 7 days post-SAH, specifically in the subset of animals in which arteriography confirmed the presence of vasospasm. Infusion of Calcimycin produced no significant changes in CBF or CVR in control animals, but resulted in a significant reduction in CBF and increase in CVR in animals 7 days after SAH and in animals with vasospasm. An infusion of histamine or bradykinin had no significant effect on CBF or CVR. CONCLUSIONS: An intracarotid infusion of acetylcholine, but not one of histamine, bradykinin, or Calcimycin, produced a measurable physiological response in the normal primate cerebrovasculature. Cerebral vasospasm that occurred after SAH produced a pathophysiological effect similar to the endothelial denudation shown in the in vitro experiments of Furchgott and Zawadzki, in which acetylcholine constricted the vessels via activation of receptors on smooth-muscle cells. Changes in vascular responses to acetylcholine and Calcimycin in animals with vasospasm, compared with control animals, provide evidence that endothelial dysfunction plays a key role in the development and/or sustenance of vasospasm after SAH.

Acetylcholine↗

Endothelial dysfunction in ischemic acute renal failure: rescue by transplanted endothelial cells.

There is accumulating circumstantial evidence suggesting that endothelial cell dysfunction contributes to the "no-reflow" phenomenon in postischemic kidneys. Here, we demonstrated the vulnerability of in vitro, ex vivo, and in vivo endothelial cells exposed to pathophysiologically relevant insults, such as oxidative and nitrosative stress or ischemia. All of these stimuli compromised the integrity of the endothelial lining. Next, we performed minimally invasive intravital microscopy of blood flow in peritubular capillaries, which provided direct evidence of the existence of the no-reflow phenomenon, attributable, at least in part, to endothelial injury. In an attempt to ameliorate the hemodynamic consequences of lost endothelial integrity, we transplanted endothelial cells or surrogate cells expressing endothelial nitric oxide synthase into rats subjected to renal artery clamping. Implantation of endothelial cells or their surrogates expressing functional endothelial nitric oxide synthase in the renal microvasculature resulted in a dramatic functional protection of ischemic kidneys. These observations strongly suggest that endothelial cell dysfunction is the primary cause of the no-reflow phenomenon, which, when ameliorated, results in prevention of renal injury seen in acute renal failure.

Acute Kidney Injury↗

Ginkgolide A attenuates homocysteine-induced endothelial dysfunction in porcine coronary arteries.

BACKGROUND: Homocysteine is an independent risk factor for atherosclerosis. The objective of this study was to investigate whether ginkgolide A (GA), a major constituent of Ginkgo biloba, could block homocysteine-induced endothelial dysfunction in porcine coronary arteries. METHODS: Porcine coronary artery rings were assigned to six treatment groups: control; homocysteine (50 micromol/L); low-dose (50 micromol/L) or high-dose (100 micromol/L) GA; and homocysteine plus low-dose or high-dose GA. After 24 hours' incubation, the rings were analyzed for vasomotor function in response to a thromboxane A2 analogue (U46619), bradykinin, and sodium nitroprusside. Endothelial nitric oxide synthase (eNOS) was studied by using real-time polymerase chain reaction and immunohistochemistry analysis. Superoxide anion production was assessed by chemoluminescence analysis. RESULTS: Endothelium-dependent relaxation (bradykinin) was significantly reduced in ring segments treated with homocysteine as compared with the control (P < .05). When homocysteine was combined with either low-dose or high-dose GA, endothelium-dependent relaxation was markedly recovered. There was no significant difference in maximal contraction (U46619) or endothelium-independent relaxation (sodium nitroprusside) among all groups. In addition, superoxide anion production was increased by 113% in the homocysteine-treated group, whereas there was no statistically significant difference between the control and GA/homocysteine groups. Furthermore, eNOS messenger RNA and protein levels were substantially reduced in the homocysteine-treated group (P < .05), but not in the GA/homocysteine combined groups. CONCLUSIONS: Homocysteine significantly impairs endothelium-dependent vasorelaxation through oxidative stress and downregulation of eNOS in porcine coronary arteries. GA effectively prevents homocysteine-induced endothelial dysfunction and molecular changes in porcine coronary arteries. This study underscores the potential clinical benefits and applications of GA in controlling homocysteine-associated vascular injury and cardiovascular disease. CLINICAL RELEVANCE: Homocysteine is an independent risk factor for atherosclerosis. This study showed that ginkgolide A, a major constituent of Ginkgo biloba, effectively prevents homocysteine-induced endothelial dysfunction and molecular changes in porcine coronary arteries. This study underscores potential clinical benefits and applications of ginkgolide A in controlling homocysteine-associated vascular injury and cardiovascular disease.

Animals↗

Endothelial dysfunction: role in obesity-related disorders and the early origins of CVD.

Atherosclerotic CVD is the most common cause of death in the West. Yet, its pathogenesis and early development are only partially understood. Central to the early atherosclerotic process is impairment of vascular endothelial function. Endothelial dysfunction can be measured non-invasively and is evident in children before clinical manifestations of atherosclerosis in adulthood. Factors in early life, such as conventional cardiovascular risk factors, or programming by perinatal growth and nutrition strongly affect endothelial function and hence the development of atherosclerosis and CVD. For instance, low birth weight and faster growth early in infancy have a detrimental effect on vascular structure and function. Childhood obesity, a key independent risk factor for CVD, also adversely affects early vascular health. Obesity is associated with endothelial dysfunction and greater arterial stiffness from as early as the first decade of life, while weight loss is beneficial. This effect on vascular function is probably mediated in part by low-grade inflammation and insulin resistance associated with obesity or by the production by adipose tissue of cytokine-like molecules, collectively termed adipokines. A high leptin concentration, in particular, is found in obese individuals and is strongly associated with vascular changes related to early atherosclerosis. The present review focuses on the early origins of endothelial dysfunction, emphasising the role of obesity. It also considers the mechanisms by which obesity impairs endothelial function, understanding of which will be important to further scientific knowledge and to improve public health.

Arteriosclerosis↗

Endothelial dysfunction: impact on epicardial coronary arteries and microcirculation.

This article examines the relationship between endothelial dysfunction and "small vessel disease." Newer technologies have facilitated the study of this issue. Using a Doppler wire and the intracoronary administration of acetylcholine and papaverine, a difference can be made between functional and chronic-trophic disturbances of the coronary reserve. Papaverine induces smooth muscle cell-mediated vasodilation, acetylcholine induces nitric oxide (NO)-mediated vasodilation. The data revealed that endothelial dysfunction may be related to disturbances in the microcirculation. In addition to those vasomotor-related properties, other factors such as antithrombotic, antiadhesive disturbances contribute to the disturbed microcirculation. Newer techniques, such as serial positron emission tomography, may yield an even better understanding of these processes.

Coronary Disease↗

Effect of atorvastatin on postcardiac transplant increase in low-density lipoprotein cholesterol reduces development of intimal hyperplasia and progression of endothelial dysfunction.

Following cardiac transplantation, accelerated coronary disease limits long-term survival. Because statins may reduce the progression of the disease in part by their anti-inflammatory effects, this study was designed to assess if atorvastatin prevented neointimal hyperplasia and endothelial dysfunction independently of baseline cholesterol levels. Patients were randomized to usual therapy (n = 13) or to 10 to 20 mg of atorvastatin (n = 12). Control subjects received niacin when their low-density lipoprotein (LDL) cholesterol levels were >130 mg/dl (n = 4). Neointimal hyperplasia by intracoronary ultrasonography, endothelial dependent vascular reactivity, and coronary flow reserve were measured at baseline and 1 year. Control group total cholesterol (203 +/- 11 to 200 +/- 13 mg/dl) and LDL (116 +/- 10 to 119 +/- 11 mg/dl) remained stable, whereas there was a nonsignificant reduction at 12 months in the atorvastatin group (total cholesterol 216 +/- 28 to 178 +/- 21 mg/dl; LDL 126 +/- 17 to 100 +/- 18 mg/dl). At 2 to 3 months there was a significant increase in total cholesterol and LDL cholesterol that was reduced with atorvastatin. At 1 year, patients taking atorvastatin showed a decrease in new or progressing lesions (2.5 +/- 1.7 vs 4.2 +/- 1.8 lesions/patient, p = 0.02), progression of maximal intimal thickness (0.12 +/- 0.07 vs 0.52 +/- 0.17 mm, p = 0.04), and percent area stenosis (5.9 +/- 2.2% vs 19.0 +/- 5.5%, p = 0.04). Atorvastatin ameliorated progressive endothelial dysfunction, whereas coronary flow reserve was unchanged in both groups. Atorvastatin administered to patients with normal or mild hypercholesterolemia in the initial year after transplant reduced the initial increase in LDL cholesterol, and, by doing so, prevented the development and progression of coronary artery lesions and endothelial dysfunction with only mild long-term decreases in cholesterol levels.

Anticholesteremic Agents↗