We explored the role of asymmetrical dimethylarginine (ADMA) as a cause of endothelial dysfunction induced by systemic inflammation. In vitro data suggest that ADMA bioavailability is regulated by proinflammatory stimuli, but it is unclear whether ADMA is a link between inflammation and endothelial dysfunction in humans. In study 1 we recruited 351 patients with coronary artery disease (CAD) and 87 healthy controls. In study 2 we recruited 69 CAD, 69 healthy, and 10 patients with rheumatoid

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... ritis, whereas in study 3, 22 healthy and 70 CAD subjects were randomly assigned to Salmonella typhii vaccination (nϭ11 healthy and nϭ60 CAD) or placebo (nϭ11 healthy and nϭ10 CAD). Circulating interleukin 6/ADMA and flow-mediated dilation (FMD) were measured at 0 and 8 hours. In study 1, ADMA was inversely correlated with FMD in healthy individuals and CAD patients (PϽ0.0001 for both). However, interleukin 6 was inversely correlated with FMD (PϽ0.0001) in healthy subjects but not in CAD patients. The positive correlation between ADMA and interleukin 6 was stronger in healthy (rϭ0.515; PϽ0.0001) compared with CAD (rϭ0.289; Pϭ0.0001) subjects. In study 2, both patients with rheumatoid arthritis and CAD had higher interleukin 6 (PϽ0.0001) and ADMA (Pϭ0.004) but lower FMD (Pϭ0.001) versus healthy subjects. In study 3, vaccination increased interleukin 6 in healthy (PϽ0.001) and CAD (PϽ0.001) subjects. FMD was reduced in healthy subjects (PϽ0.05), but its reduction in CAD was borderline. Vaccination increased ADMA only in healthy subjects (PϽ0.001). Systemic, low-grade inflammation leads to increased ADMA that may induce endothelial dysfunction. This study demonstrated that ADMA may be a link between inflammation and endothelial dysfunction in humans. (Hypertension. 2011;58:93-98.) • Online Data Supplement