Our aim was to investigate systemic nitric oxide (NO) production and its potential determinants such as insulin resistance, dyslipidemia, and circulating methylated analogs of L-arginine in uncomplicated essential hypertension (EH). Nineteen newly diagnosed, untreated male subjects with mild pure uncomplicated EH and 11 normotensive controls were studied at rest after an overnight fast. The groups had comparable age, body mass index, creatinine clearance, cholesterol, fasting glucose, and insulin. In hypertensives, the urinary excretion rate of nitrite plus nitrate (Unox), an index of endogenous NO production, was depressed (56 ± 17 vs. 77 ± 23 μmol/mmol creatinine; p < 0.05), whereas plasma levels of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO synthesis, were increased (2.4 ± 1.1 vs. 1.1 ± 0.7 μM; p < 0.005). Circulating concentrations of symmetric dimethylarginine were similar in both groups (1.4 ± 1.3 vs. 1.5 ± 1.1 μM; p = NS). The L-arginine-to-ADMA ratio was reduced in hypertension (3.3 ± 0.5 vs. 4.5 ± 0.8; p < 0.001 for ln-transformed data). There was no correlation between Unox and either the magnitude of insulin resistance or dyslipidemia in EH. Thus in male subjects with EH, endogenous systemic NO formation appears depressed, which is unrelated to accompanying insulin resistance or dyslipidemia. Circulating ADMA levels are increased in uncomplicated EH, which may be of potential relevance.

Ageing is associated with progressive endothelial dysfunction in normal humans. Flow-mediated dilation (FMD) of the brachial artery is impaired in elderly individuals with cardiovascular disease and vascular nitric oxide (NO) bioavailability is reduced. We investigated whether oral L-arginine, the substrate for NO synthesis, can improve impaired FMD in healthy very old people. In a prospective, double-blind, randomized crossover trial, 12 healthy old subjects (age 73.8 6 2.7 years) took L-arginine (8 g p.o. two times daily) or placebo for 14 days each, separated by a wash-out period of 14 days. FMD was determined by high-resolution ultrasound in the brachial artery during reactive hyperaemia. Baseline artery diameter was 3.88 6 0.18 mm. l-Arginine signifi cantly improved FMD (to 5.7 6 1.2%, p, 0.0001), whereas placebo had no effect (-0.25 6 0.7%; n.s.). After L-arginine, plasma levels of L-arginine increased signifi cantly (114.9 6 11.6 versus 57.4 6 5.0 mmol/l), but placebo had no effect. As NO synthesis can be antagonized by its endogenous inhibitor asymmetric dimethyl L-arginine (ADMA), we determined ADMA plasma concentrations, which were elevated at baseline in comparison to healthy middle-aged individuals (3.9 6 0.2 versus 1.0 6 0.1 mmol/l; p, 0.0001). ADMA remained unchanged during treatment, but L-arginine supplementation normalized the L-arginine/ADMA ratio (p, 0.05). We conclude that in healthy very old age endothelial function is impaired and may be improved by oral L-arginine supplementation, probably due to normalization of the L-arginine/ADMA ratio.

Objective: Similarities between rheumatoid arthritis (RA) and atherosclerosis include endothelial dysfunction (an antecedent of plaque formation) and depletion of circulating bone marrow–derived endothelial progenitor cells. This study was undertaken to test the hypothesis that endothelial progenitor cell depletion and subclinical atherosclerosis in RA may be related to accumulation of an endogenous inhibitor of nitric oxide (NO) synthesis, asymmetric dimethyl‐L‐arginine.Methods: We studied 30 patients with active RA and 20 age‐ and sex‐matched healthy controls. Exclusion criteria were clinically evident atherosclerosis, traditional risk factors, hyperhomocysteinemia, and renal dysfunction. The blood endothelial progenitor cell count was assayed by flow cytometry and expressed as a percentage of lymphocytes. PlasmaL‐arginine, asymmetric dimethyl‐L‐arginine, and symmetric dimethyl‐L‐arginine were measured with liquid chromatography–mass spectrometry. Mean carotid intima‐media thickness (IMT) was assessed by B‐mode ultrasound.Results: In RA patients, we found elevated levels of asymmetric dimethyl‐L‐arginine (mean ± SD 0.49 ± 0.07 μmoles/liter versus 0.40 ± 0.07 μmoles/liter in controls;P< 0.001), a depressed endothelial progenitor cell count (0.039 ± 0.025% versus 0.063 ± 0.035%;P< 0.05), and increased IMT (0.65 ± 0.13 mm versus 0.55 ± 0.10 mm;P< 0.01), with no differences in levels ofL‐arginine or symmetric dimethyl‐L‐arginine. The endothelial progenitor cell count was inversely correlated with the level of asymmetric dimethyl‐L‐arginine. IMT was positively related to the ratio of asymmetric dimethyl‐L‐arginine toL‐arginine and negatively related to the endothelial progenitor cell count, in univariate and multivariate analyses.Conclusion: Plasma asymmetric dimethyl‐L‐arginine levels are elevated in RA patients free of cardiovascular disease or risk factors. Asymmetric dimethyl‐L‐arginine accumulation may contribute to endothelial progenitor cell depletion via depressed NO‐dependent endothelial progenitor cell mobilization and/or survival, with consequent impairment of endothelial progenitor cell–mediated endothelial repair, which can promote atherogenesis in RA.

Decreased plasma levels of microRNA-223 (miR-223), predominantly of platelet origin, were proposed as a surrogate marker of efficacy of antiplatelet therapy. However, higher on-treatment platelet reactivity was associated with lower plasma miR-223 in patients with coronary artery disease (CAD) on dual antiplatelet therapy (DAPT) including clopidogrel and aspirin. Our aim was to compare plasma miR-223 and platelet reactivity in CAD patients on DAPT with newer P2Y12 antagonists vs. clopidogrel. We studied 21 men with CAD admitted to our centre owing to a non-ST-elevation acute coronary syndrome, and with an uncomplicated hospital course. From the day of admission, the patients were receiving either clopidogrel (n = 11) or prasugrel/ticagrelor (n = 10) in addition to aspirin. Before discharge, miR-223 expression in plasma was estimated by quantitative polymerase chain reaction using the comparative Ct method relative to miR-16 as an endogenous control. Multiple electrode aggregometry was used to assess platelet aggregation in response to adenosine diphosphate (ADP). ADP-induced platelet reactivity was decreased in the patients treated with prasugrel or ticagrelor compared with those on clopidogrel (mean ± SD: 139 ± 71 vs. 313 ± 162 arbitrary units [AU]*min, p = 0.006), due to a more potent antiplatelet activity of the novel P2Y12 antagonists. Consequently, six out of seven patients in the lower tertile of the ADP-induced platelet aggregation were treated with the newer P2Y12 blockers, whereas six out of seven patients in the upper tertile were on clopidogrel. Plasma miR-223 was elevated with decreasing platelet reactivity (Spearman's rho = -0.52; p = 0.015 for trend), being significantly higher in the lower tertile of the ADP-induced platelet aggregation (median [range]: 1.06 [0.25-2.31]) vs. the upper tertile (0.20 [0.13-2.30]) (p = 0.04). In conclusion, our preliminary results argue against the notion of low plasma miR-223 as a marker of platelet responsiveness to DAPT. On the contrary, more potent platelet inhibition associated mainly with newer P2Y12 antagonists appears to coincide with higher miR-223 relative to the subjects with attenuated responsiveness to DAPT.

Objectives. To estimate endothelial dysfunction in patients with rheumatoid arthritis (RA) of short duration in relation to disease activity based on the assessment of 28 joints (DAS28).Methods. We studied 29 patients (22 women, mean age 41 (SD, 9) years) with RA of short duration and 29 healthy controls. The RA subjects were divided into those with low (DAS28: 2.6–5.1,n=18) or high (DAS28>5.1,n=11) disease activity. Exclusion criteria included clinically overt atherosclerosis and other coexistent diseases. Biochemical markers of inflammatory activation and endothelial dysfunction were measured.Results. There were no significant intergroup differences in the majority of classical cardiovascular risk factors. High-sensitivity C-reactive protein, tumor necrosis factor-α, and interleukin-6 were increased in RA subjects. Compared to the controls, levels of soluble vascular cell adhesion molecule-1, von Willebrand factor, and pentraxin-3 were significantly elevated in RA subjects with low disease activity, exhibiting no further significant rises in those with high disease activity. Asymmetric dimethyl-L-arginine, soluble E-selectin, monocyte chemotactic protein-1, and osteoprotegerin were increased only in RA patients with high disease activity.Conclusions. Our findings might suggest a dissociation of pathways governing generalized and joint-specific inflammatory reactions from those involved in endothelial activation and inflammation within the vascular wall.