Since the discovery in 1980 that acetylcholine requires the presence of endothelial cells to elicit vasodilation (1), the importance of the endothelial cell layer for vascular homeostasis has been increasingly appreciated. Dysfunction of the endothelium has been implicated in the pathophysiology of different forms of cardiovascular disease, including hypertension, coronary artery disease, chronic heart failure, peripheral artery disease, diabetes, and chronic renal failure.
The endothelium, the largest organ in the body, is strategically located between the wall of blood vessels and the blood stream. It senses mechanical stimuli, such as pressure and shear stress, and hormonal stimuli, such as vasoactive substances. In response, it releases agents that regulate vasomotor function, trigger inflammatory processes, and affect hemostasis. Among the vasodilatory substances produced by the endothelium are nitric oxide (NO), prostacyclin, different endothelium-derived hyperpolarizing factors, and C-type natriuretic peptide. Vasoconstrictors include endothelin-1 (ET-1), angiotensin II (Ang II), thromboxane A2, and reactive oxygen species (ROS) (2,3). Inflammatory modulators include NO, intercellular adhesion molecule-1 (ICAM-1), vascular adhesion molecule-1 (VCAM-1), E-selectin, and NF-κB. Modulation of hemostasis includes release of plasminogen activator, tissue factor inhibitor, von Willebrand factor, NO, prostacyclin, thromboxane A2, plasminogen-activator inhibitor-1, and fibrinogen. The endothelium also contributes to mitogenesis, angiogenesis, vascular permeability, and fluid balance.
Endothelial dysfunction was initially identified as impaired vasodilation to specific stimuli such as acetylcholine or bradykinin. A broader understanding of the term would include not only reduced vasodilation but also a proinflammatory and prothrombic state associated with dysfunction of the endothelium.
Cardiovascular Disease and Endothelial Dysfunction
Endothelial dysfunction was first described in human hypertension in the forearm vasculature in 1990 (4). Impaired vasodilation in hypertension has been confirmed by many studies in different vascular beds, including small resistance vessels (5,6). In stage I essential hypertension, we have shown that ∼60% of patients exhibit impaired small artery vasodilation when this is studied in vitro on vessels dissected from gluteal subcutaneous biopsies (7). Impairment of vasodilation has also been described in type 1 (8) and type 2 diabetes (9–11), coronary artery disease (12), congestive heart failure (13), and chronic renal failure (14–16). Moreover, this manifestation of endothelial dysfunction not only is associated with cardiovascular disease but may also precede its development, as shown in a study of offspring of hypertensive patients (17). The study subjects displayed endothelial dysfunction despite being normotensive. Another study showed endothelial dysfunction in symptom-free children and young adults at high risk for atherosclerosis (18). Also, in normotensive, normoglycemic, first-degree relatives of patients with type 2 diabetes, endothelial dysfunction was correlated with insulin resistance (19). Endothelial dysfunction has been demonstrated in the metabolic syndrome and in dyslipidemia (20) and may be associated with obesity (21), hyperhomocysteinemia (22), sedentary lifestyle (23), and smoking (24), in the absence of overt cardiovascular disease.
This review concentrates on NO, oxidant excess, inflammation, and the role of endothelial dysfunction in relation to these mechanisms in cardiovascular disease. The pathophysiologic mechanisms related to endothelium-derived hyperpolarizing factors (25) and to endothelin-1 (26) have been reviewed in detail elsewhere and may be consulted by the reader.
Pathophysiology of Endothelial Dysfunction
The pathophysiology of endothelial dysfunction is complex and involves multiple mechanisms. However, some of these seem to be common to most conditions.
NO
One of the most important vasodilating substances released by the endothelium is NO, which acts as a vasodilator, inhibits growth and inflammation, and has anti-aggregant effects on platelets. Reduced NO has often been reported in the presence of impaired endothelial function. It may result from reduced activity of endothelial NO synthase (eNOS; as a result of endogenous or exogenous inhibitors or reduction in the availability of its substrate, L-arginine) and to decreased bioavailability of NO. ROS are known to quench NO with formation of peroxynitrite (27), which is a cytotoxic oxidant, and through nitration of proteins will affect protein function and therefore endothelial function. Peroxynitrite is an important mediator of oxidation of LDL, emphasizing its proatherogenic role (28). Moreover, peroxynitrite leads to degradation of the eNOS cofactor tetrahydrobiopterin (BH4) (29), leading to “uncoupling” of eNOS, as discussed below. Using a novel peroxynitrite decomposition catalyst, FP15, endothelial and cardiac dysfunction could be prevented in diabetic mice (30). Oxidant excess will also result in reduction of BH4 with increase in BH2. When this occurs, formation of the active dimer of eNOS with oxygenase activity and production of NO is curtailed (uncoupling of eNOS). The reductase function of eNOS is activated and more ROS are formed, so NO synthase goes from its oxygenase function producing NO to its reductase function producing ROS, with the consequent exaggeration of oxidant excess and deleterious effect on endothelial and vascular function (31). Oxidative excess is linked to a proinflammatory state of the vessel wall. ROS upregulate adhesion (VCAM-1 and ICAM-1) and chemotactic molecules (macrophage chemoattractant peptide-1 [MCP-1]) (28). Inflammation decreases NO bioavailability. Indeed, C-reactive protein (CRP) has been shown to decrease eNOS activity (32,33). The main source for oxidative excess in the vasculature is NAD(P)H oxidase (34,35). Other sources include xanthine oxidase (13), the mitochondria (36), and uncoupled NOS.
Asymmetric Dimethylarginine
A relatively new and attractive mechanism that leads to reduced NO is asymmetric dimethylarginine (ADMA), an endogenous competitive inhibitor of eNOS that has been linked to endothelial dysfunction. In human endothelial cells, which were stimulated with plasma from patients with chronic renal disease, inhibition of eNOS correlated with plasma ADMA levels (37). ADMA levels were inversely related to endothelium-dependent vasodilation (38) in subjects with hypercholesterolemia, and infusion of L-arginine, the substrate of eNOS and competitor of ADMA, normalized endothelial function. It has been suggested that accumulation of this endogenous eNOS inhibitor leads to reduced effective renal plasma flow and increased renovascular resistance and BP (39). Intravenous low-dose ADMA reduced heart rate and cardiac output and increased mean BP (40). ADMA is a product of protein turnover and is eliminated by excretion through the kidneys or metabolism to citrulline by the enzyme dimethylarginine dimethylaminohydrolase (DDAH). Recently, overexpression of DDAH was shown in transgenic mice to decrease ADMA, increase eNOS activity, and reduce BP (41), underlining the pathophysiologic importance of ADMA. Because ADMA is eliminated through renal excretion and degradation by DDAH, it is not surprising that it is increased in patients not only with chronic renal failure (42–44) but also with other diseases such as in presence of hepatic dysfunction (45). New interest is focusing not only on the elimination but also on the generation of ADMA. Protein-arginine methyltransferases, which produce methylated arginines, namely protein-arginine methyltransferase-1, were shown to be upregulated by shear stress, and this upregulation was associated with enhanced ADMA generation (46). Hypercholesterolemia is a risk factor for atherosclerosis, associated with endothelial dysfunction (47), and there is now also evidence that elevated ADMA levels are associated with hypercholesterolemia (38). Plasma ADMA levels were also increased in elderly hypertensive patients (39) and correlated with age and BP (48). ADMA levels have been associated with increased cardiovascular risk factors in renal failure, such as CRP, carotid intima-media thickness, concentric left ventricular hypertrophy, and left ventricular dysfunction (48–50). Moreover, it was found to be a predictor of acute coronary events (51), overall mortality of patients with chronic renal failure (52), and mortality of critical ill patients (45).
Oxidative Excess
In animal models of hypertension, oxidative excess leads to endothelial dysfunction as evidenced by improvement of the impaired endothelium-dependent relaxation after use of antioxidants (53). Oxidative excess in hypertensive patients leads to diminished NO (54) and correlates with the degree of impairment of endothelium-dependent vasodilation and with cardiovascular events (55). In patients with chronic renal failure, markers of oxidative excess also correlated with endothelial dysfunction (56). Findings in animal models of chronic renal failure suggest that enhanced generation of ROS leads to decreased NO bioavailability and endothelial dysfunction, which may be improved by antioxidant pretreatment (57,58). In humans with chronic renal failure, administration of vitamin C improved endothelial dysfunction of resistance arteries but not of conduit arteries (59). In animal models of diabetes, increased oxidative excess also led to endothelial dysfunction (60,61). ROS seem also to be involved in the mediation of endothelial injury leading to programmed cell death or apoptosis and to a form of apoptosis characterized by detachment of endothelial cells called anoikis (62). Anoikis is induced by the loss of cell-matrix interactions, but its exact mechanisms and pathophysiologic role in cardiovascular disease are not fully understood. Eicosapentaenoic acid, a polyunsaturated fatty acid contained in fish oil, was shown to protect endothelial cells from anoikis (63), which may contribute to the antiatherogenic and cardioprotective effects of fish oil.
Ang II
Ang II has been implicated in the pathophysiology of hypertension and chronic renal failure. Ang II infusion induces endothelial dysfunction in rats (64–66), increases ROS by stimulating NAD(P)H oxidase (35,67), and promotes vascular inflammation (68). In hypertensive humans, interruption of the renin-angiotensin system with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers restores endothelial function in contrast to a similar degree of BP lowering with a β-blocker, which has no effect on endothelium-dependent vasodilation (6,69,70).
Hyperhomocysteinemia
A nontraditional cardiovascular risk factor that leads to endothelial dysfunction is hyperhomocysteinemia. This has been evidenced by animal models of hyperhomocysteinemia (71). Normotensive patients with hyperhomocysteinemia display endothelial dysfunction (22). Folic acid supplementation was able to reduce homocysteine levels and improve endothelial dysfunction in children with chronic renal failure (72). Cellular (73), animal (71), and human studies (22) suggest that homocysteine reduces NO bioavailability by oxidative excess. There is now also evidence that homocysteine may cause ADMA accumulation by inhibition of DDAH (74). Experimental studies in humans have confirmed that hyperhomocysteinemia may lead to endothelial dysfunction via accumulation of ADMA (75,76). However, not all studies support this link (77). These mechanisms may explain the increased cardiovascular risk of patients with hyperhomocysteinemia. This is of special importance for patients with chronic renal failure, who often have increased homocysteine levels, which were shown to predict cardiovascular outcomes in a recent study (78).
Diabetes
In diabetes, additional mechanisms may trigger endothelial dysfunction. In states of insulin resistance, such as in type 2 diabetes, insulin signaling is altered, differently affecting the two major pathways emerging from the insulin receptor. The pathway leading via phosphoinositide 3-kinase, phosphoinositide-dependent kinase-1, and Akt/protein kinase B to phosphorylation and activation of eNOS is dramatically downregulated, whereas the pathway leading via mitogen activated protein kinases to mitogenic effects and growth is unaffected (79–82). Moreover, hyperglycemia leads to advanced glycation end products (AGE), which were shown to quench NO and impair endothelial function, as evidenced by inhibition of advanced glycosylation with aminoguanidine (83). AGE induce ROS and promote vascular inflammation, with enhanced expression of interleukin-6, VCAM-1, and MCP-1 (84). This turns into a vicious circle in diabetic nephropathy, because in renal failure, clearance of AGE is delayed, which further promotes vascular and renal injury (85). Finally, acute hyperglycemia itself can reduce NO (86) and attenuate endothelium-dependent vasodilation in humans in vivo (87).
Pathophysiologic Effects of Endothelial Dysfunction
Endothelial dysfunction has been proposed to be an early event of pathophysiologic importance in the atherosclerotic process (18,88) and provides an important link between diseases such as hypertension, chronic renal failure, or diabetes and the high risk for cardiovascular events that patients with these conditions exhibit. Low NO bioavailability can upregulate VCAM-1 in the endothelial cell layer via induction of NF-κB expression (89). ROS, CRP, CD40 ligand, and lectin-like oxidized LDL receptor-1 (LOX-1) also upregulate endothelial expression of adhesion molecules (90). The expression of VCAM-1, ICAM-1, and E-selectin plays a role in the initiation of the inflammatory process. VCAM-1 binds monocytes and T lymphocytes, the first step of invasion of the vessel wall by inflammatory cells (91). NO inhibits leukocyte adhesion (92). Reduction in NO results in induction of MCP-1 expression, which recruits mononuclear phagocytes (93). Monocytes are transformed to lipid-loaded foam cells. Oxidized LDL, for example, is scavenged through LOX-1 (94), which is highly expressed in blood vessels in hypertension, diabetes, and dyslipidemia (95). Oxidized LDL uptake by LOX-1 triggers a variety of actions: It reduces eNOS expression (96) and further stimulates adhesion molecule expression (97). LOX-1 expression can be stimulated by Ang II and endothelin-1 (98,99). As the atherosclerotic plaque progresses, growth factors secreted by macrophages in the plaque stimulate vascular smooth muscle cell growth and interstitial collagen synthesis (91). The event that initiates a majority of myocardial infarctions is the rupture of the fibrous cap of the plaque, inducing thrombus formation. Decreased NO and oxidative excess may activate matrix metalloproteinases (MMP) (100,101), namely MMP-2 and MMP-9, which weaken the fibrous cap. Because NO inhibits platelet aggregation (102), reduced NO contributes to thrombogenicity and to the severity of the event. Thus, endothelial dysfunction with reduced NO bioavailability, increased oxidant excess, and expression of adhesion molecules contributes not only to initiation but also to progression of atherosclerotic plaque formation and triggering of cardiovascular events.
Local renal endothelial dysfunction has also been implicated in the pathophysiology of acute renal failure, such as acute ischemic renal failure and hemolytic uremic syndrome. This subject is not dealt with here; it has been reviewed extensively, and readers are referred to those publications (103,104).
Prognostic Value of Endothelial Dysfunction
Because endothelial dysfunction is an early event, as pointed out above, it may be of prognostic value. In patients with and without coronary artery disease, endothelial dysfunction in coronary arteries was associated with cardiovascular events (88,105,106). Endothelial dysfunction of the peripheral vasculature also has prognostic value. Noninvasive endothelial function testing predicted cardiovascular events in patients with coronary artery disease (55), peripheral artery disease (107), and hypertension (108) and in patients who underwent vascular surgery (109). Moreover, there is increasing evidence that links markers of endothelial dysfunction and vascular inflammation with cardiovascular events. Soluble VCAM-1 (110) and interleukin-18 (111) predicted cardiovascular death in patients with coronary artery disease independently from other risk factors. In contrast, another study did not find additional predictive value of coronary artery disease to classical risk factors for the soluble adhesion molecules VCAM-1, ICAM-1, and E-selectin (112). Plasminogen activator inhibitor-1 activity has been shown to predict coronary artery disease in hemodialysis patients (113). Soluble VCAM and CRP predicted risk of death in patients with type 2 diabetes (114). Even in otherwise healthy men, soluble ICAM was a predictor of peripheral artery disease (115) and myocardial infarction (116).
Assessment of Endothelial Dysfunction
As pointed out above, the usual parameter assessed when testing endothelial function is endothelium-dependent vasodilation. In coronary arteries, this is performed angiographically by Doppler flow measurements, assessing the effect of endothelium-dependent agonists, mainly acetylcholine (106). Some have proposed the use of cold pressor test with measurement of coronary perfusion by positron emission tomography scanning as a measure of endothelial function (117). Endothelial function may be assessed on forearm resistance arteries by forearm blood flow measurement using strain-gauge plethysmography (108). Acetylcholine or metacholine is administered through an intra-arterial catheter. Because shear stress is a stimulus to the endothelium to release NO, a noninvasive technique consists of inducing increased shear stress during reactive hyperemia to assess flow-mediated vasodilation of the brachial artery by ultrasound (18). We have also assessed endothelial dysfunction of isolated resistance arteries in vitro, by obtaining vessels dissected from biopsies of gluteal subcutaneous tissue, which are then studied on a wire or a pressurized myograph. We found a good correlation between endothelial function of small arteries studied in vitro and flow-mediated dilation of the brachial artery. However, in vitro measurement seemed to be more sensitive (5). Other noninvasive techniques have emerged and include fingertip pulse pressure tonometry and measurement of intima-media thickness, which has been considered a surrogate of endothelial function (118).
Because endothelial dysfunction is paralleled by arterial inflammation, markers of endothelial dysfunction include soluble forms of ICAM-1, VCAM-1, and E-selectin, which can be assessed in plasma. New markers have been proposed, such as LOX-1, CD40 ligand, CRP, and ADMA, to name a few (90). Because ET-1 plays a pathophysiologic role in various forms of cardiovascular disease (119), it has been suggested as a potential marker of endothelial dysfunction. Although plasma ET-1 levels are elevated in patients with symptomatic atherosclerosis (120), heart failure (121), cardiogenic shock (122), primary pulmonary hypertension (123), diabetes (124), and renal failure (125), plasma ET-1 does not reliably represent levels of tissue ET-1 production and has not been found to be elevated in patients with stage 1 hypertension (126). Plasma ET-1 has not proved to be a useful clinical measurement in most conditions.
Microalbuminuria has been considered for some time an expression of endothelial dysfunction. Microalbuminuria in most pathologic conditions seems to be a disorder of the capillary wall in the glomerulus with transcapillary escape of albumin. It therefore is intriguing to assume that endothelial dysfunction parallels or contributes to albuminuria. In diabetes, endothelial dysfunction has been correlated with microalbuminuria (127) and may precede its development (128). Microalbuminuria has also been shown to correlate with markers of endothelial dysfunction (129,130) and risk of death (130) in patients with diabetes. In hypertension, several studies have suggested that microalbuminuria may reflect endothelial dysfunction (131). However, one study did not confirm the association in hypertensive subjects (132). In another study in seemingly healthy subjects, microalbuminuria but not endothelial dysfunction correlated with cardiovascular risk factors, suggesting that microalbuminuria may precede endothelial dysfunction (133). Considering that besides fenestrated endothelial cells, the basement membrane, podocytes, and tubules may contribute to microalbuminuria, it is likely that the time at which microalbuminuria and endothelial dysfunction develop may differ between diseases with different pathophysiology, even if both are somehow related.
Therapy of Endothelial Dysfunction
Endothelial dysfunction is present in various forms of cardiovascular disease. Treatment of the underlying disease may restore endothelial function, albeit only in some conditions. In patients with chronic renal failure, renal transplantation restores renal function and may improve endothelial dysfunction (134). In hypertension, reduction of BP per se does not seem to restore endothelial function. Angiotensin receptor blockers and angiotensin-converting enzyme inhibitors have been shown to be especially beneficial (6,69,70) (Figure 1). Mechanisms whereby the blockade of the renin-angiotensin system may improve endothelial function include reduction of oxidative excess and inflammation (68). In insulin-resistant states and in diabetes, the mechanisms of endothelial dysfunction are complex and the underlying targets are still not clear. It is interesting that we and others have found that peroxisome proliferator-activated receptor-γ activators (insulin sensitizers, e.g., the glitazones pioglitazone and rosiglitazone) and peroxisome proliferator-activated receptor-α activators (fibrates, e.g., fenofibrate) exhibit cardiovascular anti-inflammatory and antioxidant properties and correct endothelial dysfunction induced by Ang II (65,66,135,136) (Figure 2).
;)
Figure 1.:
Maximal acetylcholine responses (100 μmol/L) of resistance arteries from normotensive subjects and hypertensive patients, in the latter before and after 1 yr of antihypertensive treatment with losartan or atenolol. *
P < 0.05
versus normotensive subjects; †
P < 0.05
versus losartan group before treatment and
versus atenolol-treated group. Reprinted from reference
6, with permission.
Endothelium-dependent relaxation in response to acetylcholine (ACH; A) and endothelium-independent relaxation in response to SNP (B) in mesenteric arteries of angiotensin II (Ang II)-infused rats that were treated without or with pioglitazone (PIO) or rosiglitazone (ROSI) for 7 d. Results are mean ± SEM (
n = 5 to 6 per group). Relaxation is expressed as percentage increase in intraluminal diameter after precontraction with 10
−5 mol/L norepinephrine. *
P < 0.05
versus control (Ctrl). Conc., concentration. Reprinted from reference
66, with permission.
Another approach for treatment of endothelial dysfunction is to address the components in the disease process that trigger dysfunction of the endothelium. Thus, decrease of homocysteine levels in hyperhomocysteinemia by supplementation with folic acid can improve endothelial dysfunction (72,73). L-Arginine (137) and tetrahydrobiopterin, as well as tetrahydrobiopterin mimetics (138), may improve endothelial function via increased NO bioavailability. However, some studies have not found L-arginine administration to improve endothelial dysfunction (139). Recently, acetyl salicylic acid has been suggested as an agent that can reduce oxidative stress and improve endothelial function (140). Statins have proved to have beneficial effects on endothelial dysfunction (141), which may be the result in part of lipid lowering but also of their pleiotropic anti-inflammatory effects. For example, statins inhibited upregulation of LOX-1 and increased eNOS expression in human coronary artery endothelial cells (96).
New Research on Endothelium
New insights into the regulation of endothelial function will be obtained through greater understanding of the signaling pathways within endothelial cells. Research on caveolae and caveolin-1 may be of future interest, because endothelial cells exhibit high levels of caveolin-1. Caveolin-1 has been implicated in the regulation of eNOS turnover and consequently in NO release as a result of shear stress (142).
A new fascinating aspect of endothelial function is emerging from research on endothelial progenitor cells. These are primitive bone marrow cells that have the ability to mature into endothelial cells and have a physiologic role in repair of endothelial lesions (143). Levels of circulating endothelial progenitor cells correlate inversely with the degree of endothelial dysfunction in humans at various degrees of cardiovascular risk (144). It is interesting that eNOS expression by bone marrow stroma cells plays an essential role in the recruitment of endothelial progenitor cells (145). Therapy with statins increases the number of circulating endothelial progenitor cells (146). Of special interest for patients with chronic renal failure may be the finding that erythropoietin is a potent physiologic stimulus for endothelial progenitor cell mobilization (147). Moreover, transfer of endothelial progenitor cells may represent a new approach to therapy and has already had some success on peripheral ischemia and on ischemic myocardium, including promoting neovascularization and potentially transdifferentiation into cardiomyocytes (143).
D.H.E. is supported by a grant from the Deutsche Forschungsgemeinschaft. The work of E.L.S. is supported by grants 13570 and 37917 and a group grant to the Multidisciplinary Research Group on Hypertension, all from the Canadian Institutes of Health Research.
1. Furchgott RF, Zawadzki JV: The obligatory role of endothelial cells in the relaxation of arterial smooth muscle by acetylcholine. Nature 288: 373–376, 1980
2. Schiffrin EL: A critical review of the role of endothelial factors in the pathogenesis of hypertension. J Cardiovasc Pharmacol 38 [Suppl 2]: S3–S6, 2001
3. Verma S, Anderson TJ: Fundamentals of endothelial function for the clinical cardiologist. Circulation 105: 546–549, 2002
4. Panza JA, Quyyumi AA, Brush JE Jr, Epstein SE: Abnormal endothelium-dependent vascular relaxation in patients with essential hypertension. N Engl J Med 323: 22–27, 1990
5. Park JB, Charbonneau F, Schiffrin EL: Correlation of endothelial function in large and small arteries in human essential hypertension. J Hypertens 19: 415–420, 2001
6. Schiffrin EL, Park JB, Intengan HD, Touyz RM: Correction of arterial structure and endothelial dysfunction in human essential hypertension by the angiotensin receptor antagonist losartan. Circulation 101: 1653–1659, 2000
7. Park JB, Schiffrin EL: Small artery remodeling is the most prevalent (earliest?) form of target organ damage in mild essential hypertension. J Hypertens 19: 921–930, 2001
8. Beckman JA, Goldfine AB, Gordon MB, Garrett LA, Keaney JF Jr, Creager MA: Oral antioxidant therapy improves endothelial function in type 1 but not type 2 diabetes mellitus. Am J Physiol Heart Circ Physiol 285: H2392–H2398, 2003
9. Rizzoni D, Porteri E, Guelfi D, Muiesan ML, Valentini U, Cimino A, Girelli A, Rodella L, Bianchi R, Sleiman I, Rosei EA: Structural alterations in subcutaneous small arteries of normotensive and hypertensive patients with non-insulin-dependent diabetes mellitus. Circulation 103: 1238–1244, 2001
10. Schofield I, Malik R, Izzard A, Austin C, Heagerty A: Vascular structural and functional changes in type 2 diabetes mellitus: Evidence for the roles of abnormal myogenic responsiveness and dyslipidemia. Circulation 106: 3037–3043, 2002
11. Endemann D, Pu Q, De Ciuceis C, Savoia C, Virdis A, Neves MF, Touyz RM, Schiffrin EL: Persistent remodeling of resistance arteries in type 2 diabetic patients on antihypertensive treatment. Hypertension 43: 399–404, 2004
12. Monnink SH, van Haelst PL, van Boven AJ, Stroes ES, Tio RA, Plokker TW, Smit AJ, Veeger NJ, Crijns HJ, van Gilst WH: Endothelial dysfunction in patients with coronary artery disease: A comparison of three frequently reported tests. J Investig Med 50: 19–24, 2002
13. Landmesser U, Spiekermann S, Dikalov S, Tatge H, Wilke R, Kohler C, Harrison DG, Hornig B, Drexler H: Vascular oxidative stress and endothelial dysfunction in patients with chronic heart failure: Role of xanthine-oxidase and extracellular superoxide dismutase. Circulation 106: 3073–3078, 2002
14. Bolton CH, Downs LG, Victory JG, Dwight JF, Tomson CR, Mackness MI, Pinkney JH: Endothelial dysfunction in chronic renal failure: Roles of lipoprotein oxidation and pro-inflammatory cytokines. Nephrol Dial Transplant 16: 1189–1197, 2001
15. Thambyrajah J, Landray MJ, McGlynn FJ, Jones HJ, Wheeler DC, Townend JN: Abnormalities of endothelial function in patients with predialysis renal failure. Heart 83: 205–209, 2000
16. Yildiz A, Oflaz H, Pusuroglu H, Mercanoglu F, Genchallac H, Akkaya V, Ikizler TA, Sever MS: Left ventricular hypertrophy and endothelial dysfunction in chronic hemodialysis patients. Am J Kidney Dis 41: 616–623, 2003
17. Taddei S, Virdis A, Mattei P, Ghiadoni L, Sudano I, Salvetti A: Defective L-arginine-nitric oxide pathway in offspring of essential hypertensive patients. Circulation 94: 1298–1303, 1996
18. Celermajer DS, Sorensen KE, Gooch VM, Spiegelhalter DJ, Miller OI, Sullivan ID, Lloyd JK, Deanfield JE: Non-invasive detection of endothelial dysfunction in children and adults at risk of atherosclerosis. Lancet 340: 1111–1115, 1992
19. Balletshofer BM, Rittig K, Enderle MD, Volk A, Maerker E, Jacob S, Matthaei S, Rett K, Haring HU: Endothelial dysfunction is detectable in young normotensive first-degree relatives of subjects with type 2 diabetes in association with insulin resistance. Circulation 101: 1780–1784, 2000
20. Engler MM, Engler MB, Malloy MJ, Chiu EY, Schloetter MC, Paul SM, Stuehlinger M, Lin KY, Cooke JP, Morrow JD, Ridker PM, Rifai N, Miller E, Witztum JL, Mietus-Snyder M: Antioxidant vitamins C and E improve endothelial function in children with hyperlipidemia: Endothelial Assessment of Risk from Lipids in Youth (EARLY) Trial. Circulation 108: 1059–1063, 2003
21. Raitakari M, Ilvonen T, Ahotupa M, Lehtimaki T, Harmoinen A, Suomi P, Elo J, Hartiala J, Raitakri OT: Weight reduction with very-low-caloric diet and endothelial function in overweight adults: Role of plasma glucose. Arterioscler Thromb Vasc Biol 24: 124–128, 2004
22. Virdis A, Ghiadoni L, Cardinal H, Favilla S, Duranti P, Birindelli R, Magagna A, Bernini G, Salvetti G, Taddei S, Salvetti A: Mechanisms responsible for endothelial dysfunction induced by fasting hyperhomocystinemia in normotensive subjects and patients with essential hypertension. J Am Coll Cardiol 38: 1106–1115, 2001
23. Green DJ, Walsh JH, Maiorana A, Best MJ, Taylor RR, O’Driscoll JG: Exercise-induced improvement in endothelial dysfunction is not mediated by changes in CV risk factors: Pooled analysis of diverse patient populations. Am J Physiol Heart Circ Physiol 285: H2679–H2687, 2003
24. Oida K, Ebata K, Kanehara H, Suzuki J, Miyamori I: Effect of cilostazol on impaired vasodilatory response of the brachial artery to ischemia in smokers. J Atheroscler Thromb 10: 93–98, 2003
25. Campbell WB, Gauthier KM: What is new in endothelium-derived hyperpolarizing factors? Curr Opin Nephrol Hypertens 11: 177–183, 2002
26. Schiffrin EL: State-of-the-art lecture. Role of endothelin-1 in hypertension. Hypertension 34: 876–881, 1999
27. Koppenol WH, Moreno JJ, Pryor WA, Ischiropoulos H, Beckman JS: Peroxynitrite, a cloaked oxidant formed by nitric oxide and superoxide. Chem Res Toxicol 5: 834–842, 1992
28. Griendling KK, FitzGerald GA: Oxidative stress and cardiovascular injury: Part I: Basic mechanisms and in vivo monitoring of ROS. Circulation 108: 1912–1916, 2003
29. Milstien S, Katusic Z: Oxidation of tetrahydrobiopterin by peroxynitrite: Implications for vascular endothelial function. Biochem Biophys Res Commun 263: 681–684, 1999
30. Szabo C, Mabley JG, Moeller SM, Shimanovich R, Pacher P, Virag L, Soriano FG, Van Duzer JH, Williams W, Salzman AL, Groves JT: Part I: Pathogenetic role of peroxynitrite in the development of diabetes and diabetic vascular complications: Studies with FP15, a novel potent peroxynitrite decomposition catalyst. Mol Med 8: 571–580, 2002
31. Landmesser U, Dikalov S, Price SR, McCann L, Fukai T, Holland SM, Mitch WE, Harrison DG: Oxidation of tetrahydrobiopterin leads to uncoupling of endothelial cell nitric oxide synthase in hypertension. J Clin Invest 111: 1201–1209, 2003
32. Venugopal SK, Devaraj S, Yuhanna I, Shaul P, Jialal I: Demonstration that C-reactive protein decreases eNOS expression and bioactivity in human aortic endothelial cells. Circulation 106: 1439–1441, 2002
33. Verma S, Wang CH, Li SH, Dumont AS, Fedak PW, Badiwala MV, Dhillon B, Weisel RD, Li RK, Mickle DA, Stewart DJ: A self-fulfilling prophecy: C-reactive protein attenuates nitric oxide production and inhibits angiogenesis. Circulation 106: 913–919, 2002
34. Hamilton CA, Brosnan MJ, Al-Benna S, Berg G, Dominiczak AF: NAD(P)H oxidase inhibition improves endothelial function in rat and human blood vessels. Hypertension 40: 755–762, 2002
35. Touyz RM, Chen X, Tabet F, Yao G, He G, Quinn MT, Pagano PJ, Schiffrin EL: Expression of a functionally active gp91phox-containing neutrophil-type NAD(P)H oxidase in smooth muscle cells from human resistance arteries: Regulation by angiotensin II. Circ Res 90: 1205–1213, 2002
36. Du X, Matsumura T, Edelstein D, Rossetti L, Zsengeller Z, Szabo C, Brownlee M: Inhibition of GAPDH activity by poly(ADP-ribose) polymerase activates three major pathways of hyperglycemic damage in endothelial cells. J Clin Invest 112: 1049–1057, 2003
37. Xiao S, Wagner L, Schmidt RJ, Baylis C: Circulating endothelial nitric oxide synthase inhibitory factor in some patients with chronic renal disease. Kidney Int 59: 1466–1472, 2001
38. Boger RH, Bode-Boger SM, Szuba A, Tsao PS, Chan JR, Tangphao O, Blaschke TF, Cooke JP: Asymmetric dimethylarginine (ADMA): A novel risk factor for endothelial dysfunction: Its role in hypercholesterolemia. Circulation 98: 1842–1847, 1998
39. Kielstein JT, Bode-Boger SM, Frolich JC, Ritz E, Haller H, Fliser D: Asymmetric dimethylarginine, blood pressure, and renal perfusion in elderly subjects. Circulation 107: 1891–1895, 2003
40. Achan V, Broadhead M, Malaki M, Whitley G, Leiper J, MacAllister R, Vallance P: Asymmetric dimethylarginine causes hypertension and cardiac dysfunction in humans and is actively metabolized by dimethylarginine dimethylaminohydrolase. Arterioscler Thromb Vasc Biol 23: 1455–1459, 2003
41. Dayoub H, Achan V, Adimoolam S, Jacobi J, Stuehlinger MC, Wang BY, Tsao PS, Kimoto M, Vallance P, Patterson AJ, Cooke JP: Dimethylarginine dimethylaminohydrolase regulates nitric oxide synthesis: genetic and physiological evidence. Circulation 108: 3042–3047, 2003
42. Kielstein JT, Boger RH, Bode-Boger SM, Frolich JC, Haller H, Ritz E, Fliser D: Marked increase of asymmetric dimethylarginine in patients with incipient primary chronic renal disease. J Am Soc Nephrol 13: 170–176, 2002
43. Kielstein JT, Boger RH, Bode-Boger SM, Schaffer J, Barbey M, Koch KM, Frolich JC: Asymmetric dimethylarginine plasma concentrations differ in patients with end-stage renal disease: Relationship to treatment method and atherosclerotic disease. J Am Soc Nephrol 10: 594–600, 1999
44. Vallance P, Leone A, Calver A, Collier J, Moncada S: Accumulation of an endogenous inhibitor of nitric oxide synthesis in chronic renal failure. Lancet 339: 572–575, 1992
45. Nijveldt RJ, Teerlink T, Van Der Hoven B, Siroen MP, Kuik DJ, Rauwerda JA, Van Leeuwen PA: Asymmetrical dimethylarginine (ADMA) in critically ill patients: High plasma ADMA concentration is an independent risk factor of ICU mortality. Clin Nutr 22: 23–30, 2003
46. Osanai T, Saitoh M, Sasaki S, Tomita H, Matsunaga T, Okumura K: Effect of shear stress on asymmetric dimethylarginine release from vascular endothelial cells. Hypertension 42: 985–990, 2003
47. Kawano H, Motoyama T, Hirai N, Kugiyama K, Yasue H, Ogawa H: Endothelial dysfunction in hypercholesterolemia is improved by L-arginine administration: Possible role of oxidative stress. Atherosclerosis 161: 375–380, 2002
48. Miyazaki H, Matsuoka H, Cooke JP, Usui M, Ueda S, Okuda S, Imaizumi T: Endogenous nitric oxide synthase inhibitor: a novel marker of atherosclerosis. Circulation 99: 1141–1146, 1999
49. Zoccali C, Mallamaci F, Maas R, Benedetto FA, Tripepi G, Malatino LS, Cataliotti A, Bellanuova I, Boger R: Left ventricular hypertrophy, cardiac remodeling and asymmetric dimethylarginine (ADMA) in hemodialysis patients. Kidney Int 62: 339–345, 2002
50. Zoccali C, Benedetto FA, Maas R, Mallamaci F, Tripepi G, Malatino LS, Boger R: Asymmetric dimethylarginine, C-reactive protein, and carotid intima-media thickness in end-stage renal disease. J Am Soc Nephrol 13: 490–496, 2002
51. Valkonen VP, Paiva H, Salonen JT, Lakka TA, Lehtimaki T, Laakso J, Laaksonen R: Risk of acute coronary events and serum concentration of asymmetrical dimethylarginine. Lancet 358: 2127–2128, 2001
52. Zoccali C, Bode-Boger S, Mallamaci F, Benedetto F, Tripepi G, Malatino L, Cataliotti A, Bellanuova I, Fermo I, Frolich J, Boger R: Plasma concentration of asymmetrical dimethylarginine and mortality in patients with end-stage renal disease: A prospective study. Lancet 358: 2113–2117, 2001
53. Chen X, Touyz RM, Park JB, Schiffrin EL: Antioxidant effects of vitamins C and E are associated with altered activation of vascular NADPH oxidase and superoxide dismutase in stroke-prone SHR. Hypertension 38: 606–611, 2001
54. Taddei S, Virdis A, Ghiadoni L, Magagna A, Salvetti A: Vitamin C improves endothelium-dependent vasodilation by restoring nitric oxide activity in essential hypertension. Circulation 97: 2222–2229, 1998
55. Heitzer T, Schlinzig T, Krohn K, Meinertz T, Munzel T: Endothelial dysfunction, oxidative stress, and risk of cardiovascular events in patients with coronary artery disease. Circulation 104: 2673–2678, 2001
56. Annuk M, Zilmer M, Lind L, Linde T, Fellstrom B: Oxidative stress and endothelial function in chronic renal failure. J Am Soc Nephrol 12: 2747–2752, 2001
57. Hasdan G, Benchetrit S, Rashid G, Green J, Bernheim J, Rathaus M: Endothelial dysfunction and hypertension in 5/6 nephrectomized rats are mediated by vascular superoxide. Kidney Int 61: 586–590, 2002
58. Vaziri ND, Ni Z, Oveisi F, Liang K, Pandian R: Enhanced nitric oxide inactivation and protein nitration by reactive oxygen species in renal insufficiency. Hypertension 39: 135–141, 2002
59. Cross JM, Donald AE, Nuttall SL, Deanfield JE, Woolfson RG, Macallister RJ: Vitamin C improves resistance but not conduit artery endothelial function in patients with chronic renal failure. Kidney Int 63: 1433–1442, 2003
60. Frisbee JC, Stepp DW: Impaired NO-dependent dilation of skeletal muscle arterioles in hypertensive diabetic obese Zucker rats. Am J Physiol Heart Circ Physiol 281: H1304–H1311, 2001
61. Kim YK, Lee MS, Son SM, Kim IJ, Lee WS, Rhim BY, Hong KW, Kim CD: Vascular NADH oxidase is involved in impaired endothelium-dependent vasodilation in OLETF rats, a model of type 2 diabetes. Diabetes 51: 522–527, 2002
62. Taniyama Y, Griendling KK: Reactive oxygen species in the vasculature. Hypertension 42: 1075–1081, 2003
63. Suzuki T, Fukuo K, Suhara T, Yasuda O, Sato N, Takemura Y, Tsubakimoto M, Ogihara T: Eicosapentaenoic acid protects endothelial cells against anoikis through restoration of cFLIP. Hypertension 42: 342–348, 2003
64. Rajagopalan S, Kurz S, Munzel T, Tarpey M, Freeman BA, Griendling KK, Harrison DG: Angiotensin II-mediated hypertension in the rat increases vascular superoxide production via membrane NADH/NADPH oxidase activation. Contribution to alterations of vasomotor tone. J Clin Invest 97: 1916–1923, 1996
65. Diep QN, Amiri F, Touyz RM, Cohn JS, Endemann D, Neves MF, Schiffrin EL: PPARα activator effects on Ang II-induced vascular oxidative stress and inflammation. Hypertension 40: 866–871, 2002
66. Diep QN, El Mabrouk M, Cohn JS, Endemann D, Amiri F, Virdis A, Neves MF, Schiffrin EL: Structure, endothelial function, cell growth, and inflammation in blood vessels of angiotensin II-infused rats: Role of peroxisome proliferator-activated receptor-gamma. Circulation 105: 2296–2302, 2002
67. Touyz RM, Schiffrin EL: Ang II-stimulated superoxide production is mediated via phospholipase D in human vascular smooth muscle cells. Hypertension 34: 976–982, 1999
68. Schiffrin EL, Touyz RM: Multiple actions of angiotensin II in hypertension: Benefits of AT1 receptor blockade. J Am Coll Cardiol 42: 911–913, 2003
69. Schiffrin EL, Park JB, Pu Q: Effect of crossing over hypertensive patients from a beta-blocker to an angiotensin receptor antagonist on resistance artery structure an on endothelial function. J Hypertens 20: 71–78, 2002
70. Schiffrin EL: Correction of remodeling and function of small arteries in human hypertension by cilazapril, an angiotensin I-converting enzyme inhibitor. J Cardiovasc Pharmacol 27 [Suppl 2]: S13–S18, 1996
71. Virdis A, Iglarz M, Neves MF, Touyz RM, Rozen R, Schiffrin EL: Effect of hyperhomocystinemia and hypertension on endothelial function in methylenetetrahydrofolate reductase-deficient mice. Arterioscler Thromb Vasc Biol 23: 1352–1357, 2003
72. Bennett-Richards K, Kattenhorn M, Donald A, Oakley G, Varghese Z, Rees L, Deanfield JE: Does oral folic acid lower total homocysteine levels and improve endothelial function in children with chronic renal failure? Circulation 105: 1810–1815, 2002
73. Zhang X, Li H, Jin H, Ebin Z, Brodsky S, Goligorsky MS: Effects of homocysteine on endothelial nitric oxide production. Am J Physiol Renal Physiol 279: F671–F678, 2000
74. Stuhlinger MC, Tsao PS, Her JH, Kimoto M, Balint RF, Cooke JP: Homocysteine impairs the nitric oxide synthase pathway: Role of asymmetric dimethylarginine. Circulation 104: 2569–2575, 2001
75. Stuhlinger MC, Oka RK, Graf EE, Schmolzer I, Upson BM, Kapoor O, Szuba A, Malinow MR, Wascher TC, Pachinger O, Cooke JP: Endothelial dysfunction induced by hyperhomocyst(e)inemia: Role of asymmetric dimethylarginine. Circulation 108: 933–938, 2003
76. Boger RH, Lentz SR, Bode-Boger SM, Knapp HR, Haynes WG: Elevation of asymmetrical dimethylarginine may mediate endothelial dysfunction during experimental hyperhomocyst(e)inaemia in humans. Clin Sci (Lond) 100: 161–167, 2001
77. Wanby P, Brattstrom L, Brudin L, Hultberg B, Teerlink T: Asymmetric dimethylarginine and total homocysteine in plasma after methionine loading. Scand J Lab Invest 63: 347–357, 2003
78. Mallamaci F, Zoccali C, Tripepi G, Fermo I, Benedetto FA, Cataliotti A, Bellanuova I, Malatino LS, Soldarini A: Hyperhomocysteinemia predicts cardiovascular outcomes in hemodialysis patients. Kidney Int 61: 609–614, 2002
79. Cusi K, Maezono K, Osman A, Pendergrass M, Patti ME, Pratipanawatr T, DeFronzo RA, Kahn CR, Mandarino LJ: Insulin resistance differentially affects the PI 3-kinase- and MAP kinase-mediated signaling in human muscle. J Clin Invest 105: 311–320, 2000
80. Montagnani M, Ravichandran LV, Chen H, Esposito DL, Quon MJ: Insulin receptor substrate-1 and phosphoinositide-dependent kinase-1 are required for insulin-stimulated production of nitric oxide in endothelial cells. Mol Endocrinol 16: 1931–1942, 2002
81. Osman AA, Pendergrass M, Koval J, Maezono K, Cusi K, Pratipanawatr T, Mandarino LJ: Regulation of MAP kinase pathway activity in vivo in human skeletal muscle. Am J Physiol Endocrinol Metab 278: E992–E999, 2000
82. Federici M, Menghini R, Mauriello A, Hribal ML, Ferrelli F, Lauro D, Sbraccia P, Spagnoli LG, Sesti G, Lauro R: Insulin-dependent activation of endothelial nitric oxide synthase is impaired by O-linked glycosylation modification of signaling proteins in human coronary endothelial cells. Circulation 106: 466–472, 2002
83. Bucala R, Tracey KJ, Cerami A: Advanced glycosylation products quench nitric oxide and mediate defective endothelium-dependent vasodilatation in experimental diabetes. J Clin Invest 87: 432–438, 1991
84. Zhang L, Zalewski A, Liu Y, Mazurek T, Cowan S, Martin JL, Hofmann SM, Vlassara H, Shi Y: Diabetes-induced oxidative stress and low-grade inflammation in porcine coronary arteries. Circulation 108: 472–478, 2003
85. Makita Z, Radoff S, Rayfield EJ, Yang Z, Skolnik E, Delaney V, Friedman EA, Cerami A, Vlassara H: Advanced glycosylation end products in patients with diabetic nephropathy. N Engl J Med 325: 836–842, 1991
86. Giugliano D, Marfella R, Coppola L, Verrazzo G, Acampora R, Giunta R, Nappo F, Lucarelli C, D’Onofrio F: Vascular effects of acute hyperglycemia in humans are reversed by L-arginine. Evidence for reduced availability of nitric oxide during hyperglycemia. Circulation 95: 1783–1790, 1997
87. Williams SB, Goldfine AB, Timimi FK, Ting HH, Roddy MA, Simonson DC, Creager MA: Acute hyperglycemia attenuates endothelium-dependent vasodilation in humans in vivo. Circulation 97: 1695–1701, 1998
88. Suwaidi JA, Hamasaki S, Higano ST, Nishimura RA, Holmes DR Jr, Lerman A: Long-term follow-up of patients with mild coronary artery disease and endothelial dysfunction. Circulation 101: 948–954, 2000
89. Khan BV, Harrison DG, Olbrych MT, Alexander RW, Medford RM: Nitric oxide regulates vascular cell adhesion molecule 1 gene expression and redox-sensitive transcriptional events in human vascular endothelial cells. Proc Natl Acad Sci U S A 93: 9114–9119, 1996
90. Szmitko PE, Wang CH, Weisel RD, de Almeida JR, Anderson TJ, Verma S: New markers of inflammation and endothelial cell activation: Part I. Circulation 108: 1917–1923, 2003
91. Libby P: Inflammation in atherosclerosis. Nature 420: 868–874, 2002
92. Kubes P, Suzuki M, Granger DN: Nitric oxide: An endogenous modulator of leukocyte adhesion. Proc Natl Acad Sci U S A 88: 4651–4655, 1991
93. Zeiher AM, Fisslthaler B, Schray-Utz B, Busse R: Nitric oxide modulates the expression of monocyte chemoattractant protein 1 in cultured human endothelial cells. Circ Res 76: 980–986, 1995
94. Yoshida H, Kondratenko N, Green S, Steinberg D, Quehenberger O: Identification of the lectin-like receptor for oxidized low-density lipoprotein in human macrophages and its potential role as a scavenger receptor. Biochem J 334: 9–13, 1998
95. Mehta JL, Li D: Identification, regulation and function of a novel lectin-like oxidized low-density lipoprotein receptor. J Am Coll Cardiol 39: 1429–1435, 2002
96. Mehta JL, Li DY, Chen HJ, Joseph J, Romeo F: Inhibition of LOX-1 by statins may relate to upregulation of eNOS. Biochem Biophys Res Commun 289: 857–861, 2001
97. Chen H, Li D, Saldeen T, Mehta JL: Transforming growth factor-beta(1) modulates oxidatively modified LDL-induced expression of adhesion molecules: role of LOX-1. Circ Res 89: 1155–1160, 2001
98. Morawietz H, Duerrschmidt N, Niemann B, Galle J, Sawamura T, Holtz J: Induction of the oxLDL receptor LOX-1 by endothelin-1 in human endothelial cells. Biochem Biophys Res Commun 284: 961–965, 2001
99. Morawietz H, Rueckschloss U, Niemann B, Duerrschmidt N, Galle J, Hakim K, Zerkowski HR, Sawamura T, Holtz J: Angiotensin II induces LOX-1, the human endothelial receptor for oxidized low-density lipoprotein. Circulation 100: 899–902, 1999
100. Uemura S, Matsushita H, Li W, Glassford AJ, Asagami T, Lee KH, Harrison DG, Tsao PS: Diabetes mellitus enhances vascular matrix metalloproteinase activity: Role of oxidative stress. Circ Res 88: 1291–1298, 2001
101. Eberhardt W, Beeg T, Beck KF, Walpen S, Gauer S, Bohles H, Pfeilschifter J: Nitric oxide modulates expression of matrix metalloproteinase-9 in rat mesangial cells. Kidney Int 57: 59–69, 2000
102. Radomski MW, Palmer RM, Moncada S: The role of nitric oxide and cGMP in platelet adhesion to vascular endothelium. Biochem Biophys Res Commun 148: 1482–1489, 1987
103. Sutton TA, Fisher CJ, Molitoris BA: Microvascular endothelial injury and dysfunction during ischemic acute renal failure. Kidney Int 62: 1539–1549, 2002
104. Zoja C, Morigi M, Remuzzi G: The role of the endothelium in hemolytic uremic syndrome. J Nephrol 14: S58–S62, 2001
105. Halcox JP, Schenke WH, Zalos G, Mincemoyer R, Prasad A, Waclawiw MA, Nour KR, Quyyumi AA: Prognostic value of coronary vascular endothelial dysfunction. Circulation 106: 653–658, 2002
106. Schachinger V, Britten MB, Zeiher AM: Prognostic impact of coronary vasodilator dysfunction on adverse long-term outcome of coronary heart disease. Circulation 101: 1899–1906, 2000
107. Gokce N, Keaney JF Jr, Hunter LM, Watkins MT, Nedeljkovic ZS, Menzoian JO, Vita JA: Predictive value of noninvasively determined endothelial dysfunction for long-term cardiovascular events in patients with peripheral vascular disease. J Am Coll Cardiol 41: 1769–1775, 2003
108. Perticone F, Ceravolo R, Pujia A, Ventura G, Iacopino S, Scozzafava A, Ferraro A, Chello M, Mastroroberto P, Verdecchia P, Schillaci G: Prognostic significance of endothelial dysfunction in hypertensive patients. Circulation 104: 191–196, 2001
109. Gokce N, Keaney JF Jr, Hunter LM, Watkins MT, Menzoian JO, Vita JA: Risk stratification for postoperative cardiovascular events via noninvasive assessment of endothelial function: a prospective study. Circulation 105: 1567–1572, 2002
110. Blankenberg S, Rupprecht HJ, Bickel C, Peetz D, Hafner G, Tiret L, Meyer J: Circulating cell adhesion molecules and death in patients with coronary artery disease. Circulation 104: 1336–1342, 2001
111. Blankenberg S, Tiret L, Bickel C, Peetz D, Cambien F, Meyer J, Rupprecht HJ: Interleukin-18 is a strong predictor of cardiovascular death in stable and unstable angina. Circulation 106: 24–30, 2002
112. Malik I, Danesh J, Whincup P, Bhatia V, Papacosta O, Walker M, Lennon L, Thomson A, Haskard D: Soluble adhesion molecules and prediction of coronary heart disease: A prospective study and meta-analysis. Lancet 358: 971–976, 2001
113. Segarra A, Chacon P, Martinez-Eyarre C, Argelaguer X, Vila J, Ruiz P, Fort J, Bartolome J, Camps J, Moliner E, Pelegri A, Marco F, Olmos A, Piera L: Circulating levels of plasminogen activator inhibitor type-1, tissue plasminogen activator, and thrombomodulin in hemodialysis patients: Biochemical correlations and role as independent predictors of coronary artery stenosis. J Am Soc Nephrol 12: 1255–1263, 2001
114. Stehouwer CD, Gall MA, Twisk JW, Knudsen E, Emeis JJ, Parving HH: Increased urinary albumin excretion, endothelial dysfunction, and chronic low-grade inflammation in type 2 diabetes: Progressive, interrelated, and independently associated with risk of death. Diabetes 51: 1157–1165, 2002
115. Pradhan AD, Rifai N, Ridker PM: Soluble intercellular adhesion molecule-1, soluble vascular adhesion molecule-1, and the development of symptomatic peripheral arterial disease in men. Circulation 106: 820–825, 2002
116. Ridker PM, Hennekens CH, Roitman-Johnson B, Stampfer MJ, Allen J: Plasma concentration of soluble intercellular adhesion molecule 1 and risks of future myocardial infarction in apparently healthy men. Lancet 351: 88–92, 1998
117. Schindler TH, Nitzsche EU, Munzel T, Olschewski M, Brink I, Jeserich M, Mix M, Buser PT, Pfisterer M, Solzbach U, Just H: Coronary vasoregulation in patients with various risk factors in response to cold pressor testing: Contrasting myocardial blood flow responses to short- and long-term vitamin C administration. J Am Coll Cardiol 42: 814–822, 2003
118. Ganz P, Vita JA: Testing endothelial vasomotor function: Nitric oxide, a multipotent molecule. Circulation 108: 2049–2053, 2003
119. Schiffrin EL, Intengan HD, Thibault G, Touyz RM: Clinical significance of endothelin in cardiovascular disease. Curr Opin Cardiol 12: 354–367, 1997
120. Lerman A, Edwards BS, Hallett JW, Heublein DM, Sandberg SM, Burnett JC Jr: Circulating and tissue endothelin immunoreactivity in advanced atherosclerosis. N Engl J Med 325: 997–1001, 1991
121. Pacher R, Stanek B, Hulsmann M, Koller-Strametz J, Berger R, Schuller M, Hartter E, Ogris E, Frey B, Heinz G, Maurer G: Prognostic impact of big endothelin-1 plasma concentrations compared with invasive hemodynamic evaluation in severe heart failure. J Am Coll Cardiol 27: 633–641, 1996
122. Cernacek P, Stewart DJ: Immunoreactive endothelin in human plasma: Marked elevations in patients in cardiogenic shock. Biochem Biophys Res Commun 161: 562–567, 1989
123. Stewart DJ, Levy RD, Cernacek P, Langleben D: Increased plasma endothelin-1 in pulmonary hypertension: Marker or mediator of disease? Ann Intern Med 114: 464–469, 1991
124. Schneider JG, Tilly N, Hierl T, Sommer U, Hamann A, Dugi K, Leidig-Bruckner G, Kasperk C: Elevated plasma endothelin-1 levels in diabetes mellitus. Am J Hypertens 15: 967–972, 2002
125. Deray G, Carayon A, Maistre G, Benhmida M, Masson F, Barthelemy C, Petitclerc T, Jacobs C: Endothelin in chronic renal failure. Nephrol Dial Transplant 7: 300–305, 1992
126. Schiffrin EL, Thibault G: Plasma endothelin in human essential hypertension. Am J Hypertens 4: 303–308, 1991
127. Feldt-Rasmussen B: Microalbuminuria, endothelial dysfunction and cardiovascular risk. Diabetes Metab 26: 64–66, 2000
128. Lim SC, Caballero AE, Smakowski P, LoGerfo FW, Horton ES, Veves A: Soluble intercellular adhesion molecule, vascular cell adhesion molecule, and impaired microvascular reactivity are early markers of vasculopathy in type 2 diabetic individuals without microalbuminuria. Diabetes Care 22: 1865–1870, 1999
129. Stehouwer CD, Nauta JJ, Zeldenrust GC, Hackeng WH, Donker AJ, den Ottolander GJ: Urinary albumin excretion, cardiovascular disease, and endothelial dysfunction in non-insulin-dependent diabetes mellitus. Lancet 340: 319–323, 1992
130. Clausen P, Jensen JS, Jensen G, Borch-Johnsen K, Feldt-Rasmussen B: Elevated urinary albumin excretion is associated with impaired arterial dilatory capacity in clinically healthy subjects. Circulation 103: 1869–1874, 2001
131. Pedrinelli R, Giampietro O, Carmassi F, Melillo E, Dell’Omo G, Catapano G, Matteucci E, Talarico L, Morale M, De Negri F, et al: Microalbuminuria and endothelial dysfunction in essential hypertension. Lancet 344: 14–18, 1994
132. Taddei S, Virdis A, Mattei P, Ghiadoni L, Sudano I, Arrighi P, Salvetti A: Lack of correlation between microalbuminuria and endothelial function in essential hypertensive patients. J Hypertens 13: 1003–1008, 1995
133. Diercks GF, Stroes ES, van Boven AJ, van Roon AM, Hillege HL, de Jong PE, Smit AJ, Gans RO, Crijns HJ, Rabelink TJ, van Gilst WH: Urinary albumin excretion is related to cardiovascular risk indicators, not to flow-mediated vasodilation, in apparently healthy subjects. Atherosclerosis 163: 121–126, 2002
134. Passauer J, Bussemaker E, Lassig G, Gross P: Kidney transplantation improves endothelium-dependent vasodilation in patients with endstage renal disease. Transplantation 75: 1907–1910, 2003
135. Schiffrin EL, Amiri F, Benkirane K, Iglarz M, Diep QN: Peroxisome proliferator-activated receptors: Vascular and cardiac effects in hypertension. Hypertension 42: 664–668, 2003
136. Iglarz M, Touyz RM, Amiri F, Lavoie MF, Diep QN, Schiffrin EL: Effect of peroxisome proliferator-activated receptor-alpha and -gamma activators on vascular remodeling in endothelin-dependent hypertension. Arterioscler Thromb Vasc Biol 23: 45–51, 2003
137. Popov D, Costache G, Georgescu A, Enache M: Beneficial effects of L-arginine supplementation in experimental hyperlipemia-hyperglycemia in the hamster. Cell Tissue Res 308: 109–120, 2002
138. Hyndman ME, Verma S, Rosenfeld RJ, Anderson TJ, Parsons HG: Interaction of 5-methyltetrahydrofolate and tetrahydrobiopterin on endothelial function. Am J Physiol Heart Circ Physiol 282: H2167–H2172, 2002
139. Cross JM, Donald AE, Kharbanda R, Deanfield JE, Woolfson RG, Macallister RJ: Acute administration of L-arginine does not improve arterial endothelial function in chronic renal failure. Kidney Int 60: 2318–2323, 2001
140. Wu R, Lamontagne D, de Champlain J: Antioxidative properties of acetylsalicylic Acid on vascular tissues from normotensive and spontaneously hypertensive rats. Circulation 105: 387–392, 2002
141. Dogra GK, Watts GF, Herrmann S, Thomas MA, Irish AB: Statin therapy improves brachial artery endothelial function in nephrotic syndrome. Kidney Int 62: 550–557, 2002
142. Frank PG, Woodman SE, Park DS, Lisanti MP: Caveolin, caveolae, and endothelial cell function. Arterioscler Thromb Vasc Biol 23: 1161–1168, 2003
143. Szmitko PE, Fedak PW, Weisel RD, Stewart DJ, Kutryk MJ, Verma S: Endothelial progenitor cells: new hope for a broken heart. Circulation 107: 3093–3100, 2003
144. Hill JM, Zalos G, Halcox JP, Schenke WH, Waclawiw MA, Quyyumi AA, Finkel T: Circulating endothelial progenitor cells, vascular function, and cardiovascular risk. N Engl J Med 348: 593–600, 2003
145. Aicher A, Heeschen C, Mildner-Rihm C, Urbich C, Ihling C, Technau-Ihling K, Zeiher AM, Dimmeler S: Essential role of endothelial nitric oxide synthase for mobilization of stem and progenitor cells. Nat Med 9: 1370–1376, 2003
146. Vasa M, Fichtlscherer S, Adler K, Aicher A, Martin H, Zeiher AM, Dimmeler S: Increase in circulating endothelial progenitor cells by statin therapy in patients with stable coronary artery disease. Circulation 103: 2885–2890, 2001
147. Heeschen C, Aicher A, Lehmann R, Fichtlscherer S, Vasa M, Urbich C, Mildner-Rihm C, Martin H, Zeiher AM, Dimmeler S: Erythropoietin is a potent physiologic stimulus for endothelial progenitor cell mobilization. Blood 102: 1340–1346, 2003
