Incubation of human endothelial cells with ADMA inhibited NO formation, increased oxidative stress, and potentiated monocyte binding, suggesting it may be an endogenous proatherogenic molecule.
Does asymmetric dimethylarginine (ADMA) inhibit nitric oxide elaboration and increase endothelial adhesiveness for monocytes in cultured human endothelial cells?
ADMA acts as an endogenous inhibitor of nitric oxide synthase, increasing endothelial oxidative stress and monocyte binding, suggesting it is a proatherogenic molecule.
OBJECTIVES: We sought to determine whether asymmetric dimethylarginine (ADMA) inhibits nitric oxide (NO) elaboration in cultured human endothelial cells and whether this is associated with the activation of oxidant-sensitive signaling mediating endothelial adhesiveness for monocytes. BACKGROUND: Endothelial NO elaboration is impaired in hypercholesterolemia and atherosclerosis, which may be due to elevated concentrations of ADMA, an endogenous inhibitor of NO synthase. METHODS: Human umbilical vein endothelial cells (ECV 304) and human monocytoid cells (THP-1) were studied in a functional binding assay. Nitric oxide and superoxide anion (O2-) were measured by chemiluminescence; ADMA by high pressure liquid chromatography; monocyte chemotactic protein-1 (MCP-1) by ELISA and NF-KB by electromobility gel shift assay. RESULTS: Incubation of endothelial cells with ADMA (0.1 microM to 100 microM) inhibited NO formation, which was reversed by coincubation with L-arginine (1 mM). The biologically inactive stereoisomer symmetric dimethylarginine did not inhibit NO release. Asymmetric dimethylarginine (10 microM) or native low-density lipoprotein cholesterol (100 mg/dL) increased endothelial O2- to the same degree. Asymmetric dimethylarginine also stimulated MCP-1 formation by endothelial cells. This effect was paralleled by activation of the redox-sensitive transcription factor NF-KB. Preincubation of endothelial cells with ADMA increased the adhesiveness of endothelial cells for THP-1 cells in a concentration-dependent manner. Asymmetric dimethylarginine-induced monocyte binding was diminished by L-arginine or by a neutralizing anti-MCP-1 antibody. CONCLUSIONS: We concluded that the endogenous NO synthase inhibitor ADMA is synthesized in human endothelial cells. Asymmetric dimethylarginine increases endothelial oxidative stress and potentiates monocyte binding. Asymmetric dimethylarginine may be an endogenous proatherogenic molecule.
Böger et al. (2000) studied this question. Asymmetric dimethylarginine (ADMA) vs. Symmetric dimethylarginine or control was evaluated on Nitric oxide (NO) formation and endothelial adhesiveness for monocytes. Incubation of human endothelial cells with ADMA inhibited NO formation, increased oxidative stress, and potentiated monocyte binding, suggesting it may be an endogenous proatherogenic molecule.