Is asymmetric dimethylarginine a novel marker of atherosclerosis?

Abstract

To the Editor: In their article, Miyazaki et al1 demonstrate a correlation between the plasma concentration of asymmetric dimethylarginine (ADMA) and carotid artery intima-media thickness in humans. In multivariate regression analyses, ADMA was the only significant predictor of carotid intima-media thickness besides age and impaired glucose tolerance. However, one critical factor must be carefully evaluated in the interpretation of these data: dimethylarginines are a pair of endogenous, dimethylated L-arginine analogues. ADMA inhibits nitric oxide (NO) synthase,2 whereas its stereoisomer, symmetric dimethylarginine (SDMA), is biologically inactive.2 Unfortunately, Miyazaki et al1 gave only a brief description of the high performance liquid chromatographic (HPLC) method they used to quantify ADMA levels. When examining the article to which they refer for a description of their method,3 it seemed that the investigators could not distinguish between ADMA and SDMA with the HPLC system. This is unfortunate because SDMA probably plays no role in vascular …