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The endothelium plays a crucial role in modulating vascular function and structure. In healthy conditions, nitric oxide produced by endothelial cells exerts not only vasodilating properties, but also several other protective actions toward the vessel wall against the development of atherosclerosis and thrombosis. Traditional cardiovascular risk factors are characterized by endothelial dysfunction caused by an enhanced production of oxidative stress leading to destroy nitric oxide, thus reducing its availability. Abdominal obesity is associated with endothelial dysfunction, through direct mechanisms, such as insulin resistance and the association with risk factors (including diabetes mellitus, hypertension and dyslipidemia), and direct, by the production of adipokines and pro-inflammatory cytokines, which in turn induce oxidative stress leading to a reduced nitric oxide availability. A reduced endothelium-dependent relaxation is a predictor of cardiovascular events in high-risk patients and represents a putative clinical parameter to stratify the cardiovascular risk and a useful marker for therapy efficacy. Weight loss and a modification of lifestyle ameliorate endothelial function in obese patients, an effect due not only to a better glycemic profile, but also secondary to reduced plasma levels of inflammatory markers and adipokines. At present, whether an improvement of endothelial dysfunction secondary to weight loss is significantly associated with a better cardiovascular prognosis is still unknown. (G Ital Cardiol 2006; 7 (11): 715-723)

Background: Sedentary aging is associated with oxidative stress and endothelial dysfunction. The aim of this study was to evaluate the relationship between long-term physical activity, plasma antioxidant status, and conduit artery endothelial function in young and older healthy men., Methods: In young (n = 16) and older athletes (n = 16) and in matched healthy sedentary subjects, endothelium-dependent flow-mediated dilation (FMD) and endothelium-independent response to glyceryl trinitrate (GTN), 400 microg, were measured in the brachial artery from high-resolution ultrasonography. Plasma malondialdehyde (MDA) and antioxidant capacity as total oxyradical scavenging capacity (TOSC) were also evaluated., Results: We found that FMD was lower (< or =0.01) in sedentary older subjects (2.3% +/- 1.0%) as compared with older athletes (5.3% +/- 3.2%) and both sedentary (5.4% +/- 2.0%) and athletically trained (6.1% +/- 3.2%) young subjects. Sedentary older subjects showed higher (P < or = .05) MDA levels and lower (P < .0001) plasma antioxidant capacity as compared with the other subgroups, whereas in older athletes MDA levels and antioxidant capacity were similar to those observed in the young subgroups. In the whole group, FMD, but not GTN, was negatively related to age (r = -0.31, P < .05) and directly related (P < or = .01) to VO2max (r = 0.49) and TOSC against peroxyl (r = 0.69) and hydroxyl radicals (r = 0.53). In the multivariate analysis, TOSC against peroxyl radicals resulted as the most significant predictor of FMD (R2 = 0.60; P = .003)., Conclusions: These results suggest that regular physical activity is associated with preserved antioxidant defenses and endothelial function in older individuals.

Objectives: We assessed whether third-generation oral contraceptive (OC) treatment (30 microg ethinylestradiol + 75 microg gestodene daily) could affect the endothelial function of healthy women., Methods: In 20 young healthy women (HW) and 10 hypercholesterolemic women (CW) we assessed forearm blood flow (strain-gauge plethysmography) changes induced by the intrabrachial infusion of acetylcholine (ACH) (0.15-15 microg/100 ml forearm tissue/min) and sodium nitroprusside (SNP) (1-4 microg/100 ml forearm tissue/min). ACH was repeated during the nitric oxide synthase inhibitor intra-arterial NG-monomethyl-L-arginine (L-NMMA) (100 microg/100 ml forearm tissue/min) or the antioxidant vitamin C (8 mg/100 ml forearm tissue/min). HW repeated the protocol after 6-month OC (n = 10) or placebo (n = 10) treatment., Results: In HW the maximal vasodilation to ACH, similar between placebo and OC subgroups, was significantly reduced in CW (P < 0.01). Vasodilation to ACH was blunted (P < 0.01) by L-NMMA and unaffected by vitamin C, in both OC and placebo groups. In CW the vasodilation to ACH, not modified by L-NMMA, was improved by vitamin C (P < 0.01). OC treatment raised (P < 0.01) plasma total and low-density lipoprotein cholesterol, and values were similar to those shown by CW. Both OC and placebo intake did not change the response to ACH and the modulation induced by L-NMMA or vitamin C. Vasodilation to SNP was similar in all groups., Conclusions: In HW 6-month treatment with third-generation OC, although associated with an abnormal lipid profile, does not adversely affect endothelium-dependent vasodilation. This neutral effect could be the balance between a deleterious effect of hypercholesterolemia and a protective effect of OC on endothelial function.

Endothelium plays an important role in the modulation of vascular tone and structure mainly through the production of nitric oxide (NO), which causes local vasodilation and counteracts processes leading to atherothrombosis. A dysfunctioning endothelium, characterized by reduced NO availability owing to impairment of the L-arginine-NO pathway and, above all, to production of oxygen free radicals, can impair local vasomotion and promote the development of atherosclerosis and of atherothrombotic vascular events. Aging is associated with endothelial dysfunction both in normotensive subjects and in hypertensive patients, and hypertension seems to induce earlier onset of those mechanisms (i.e. impairment of the L-arginine-NO pathway and oxidative stress) that cause age-related endothelial dysfunction. Premenopausal normotensive women are protected against the deleterious effect of aging on endothelial function, and age-related impairment of endothelial function is attenuated in premenopausal hypertensive women. This protective effect on endothelial function seems to be mediated by endogenous estrogen, which preserves NO availability by activating the L-arginine-NO pathway in normotensive women and, again, by activating this pathway but above all by inhibiting oxidative stress in hypertensive women. Thus, the protective effect of endogenous estrogen on endothelial function could be a plausible mechanism contributing to the lower cardiovascular risk of premenopausal women. Finally, whether endogenous androgen can impair endothelial function is still an unsolved issue since data concerning the effect of testosterone on endothelial function are scanty and contradictory.

Objectives: We sought to evaluate whether fasting hyperhomocystinemia reduces endothelial function by oxidative stress in normotensive subjects and hypertensive patients., Background: Subjects with hyperhomocystinemia have endothelial dysfunction., Methods: In 23 normotensive subjects and 28 hypertensive patients, classified into normohomocystinemic and hyperhomocystinemic groups according to homocysteine plasma levels (< 8.7 and >14.6 micromol/l, respectively), we studied forearm blood flow changes (strain-gauge plethysmography) induced by intrabrachial administration of acetylcholine (0.15 to 15 microg/100 ml tissue per min) or sodium nitroprusside (1 to 4 microg/100 ml per min), an endothelium-dependent and -independent vasodilator, respectively. Acetylcholine was repeated with N(G)-monomethyl-L-arginine (L-NMMA; 100 microg/100 ml per min), vitamin C (8 mg/100 ml per min) and L-NMMA plus vitamin C., Results: Normotensive hyperhomocystinemic patients showed a blunted response to acetylcholine and a lower inhibiting effect of L-NMMA on acetylcholine, as compared with normohomocystinemic patients. Although vitamin C was ineffective in normohomocystinemic subjects, it increased the response to acetylcholine and restored the inhibiting effect of L-NMMA on acetylcholine in hyperhomocystinemic patients. Hypertensive hyperhomocystinemic patients showed a reduced response to acetylcholine, as compared with normohomocystinemic subjects. In both subgroups, L-NMMA failed to blunt the response to acetylcholine. The potentiating effect of vitamin C on acetylcholine was greater in hyperhomocystinemic patients than in normohomocystinemic subjects, although it restored the inhibitory effect of L-NMMA on acetylcholine-induced vasodilation to the same extent in both groups. Hyperhomocystinemia did not change the response to sodium nitroprusside., Conclusions: In normotensive subjects and hypertensive patients, hyperhomocystinemia impairs endothelium-dependent vasodilation. It could be related to oxidant activity.

Endothelium can deeply influence vascular tone and structure. The main endothelium derived factor is nitric oxide, which is not only a potent vasodilator but also inhibits platelet aggregation, smooth muscle cell migration and proliferation, monocyte adhesion and adhesion molecule expression, thus protecting the vessel wall against the development of atherosclerosis and thrombosis. In human hypertension, endothelial dysfunction has been documented in peripheral and coronary macro and microcirculation and in renal circulation. Impaired endothelium-dependent vasodilation associated with essential hypertension seems to be a primary phenomenon, since it can be detected in the offspring of essential hypertensive patients, shows no clear correlation with blood pressure value, and is not normalized by the mere reduction of blood pressure. The phenomenon responsible for endothelial alteration in essential hypertensive patients seems to be the activation of an alternative pathway involving cyclooxygenase which reduces NO availability through production of oxidative stress. This alteration in the NO pathway could be the main mechanism through which a dysfunctional endothelium could be a promoter of atherosclerosis and thrombosis in essential hypertension.