Circulation research
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Circulation research · Feb 2003
Regulation of cytokine-induced nitric oxide synthesis by asymmetric dimethylarginine: role of dimethylarginine dimethylaminohydrolase.
In response to vascular insults, inflammatory cytokines stimulate vascular smooth muscle cells (SMCs) to express an inducible isoform of nitric oxide synthase (iNOS). Asymmetric dimethylarginine (ADMA), an endogenous NO synthase inhibitor, is metabolized by dimethylarginine dimethylaminohydrolase (DDAH). To determine whether the ADMA-DDAH system regulates cytokine-induced NO production, cultured rat SMCs were exposed to interleukin-1beta (IL-1beta). ⋯ Exogenous administration of NO donors (SNAP and SIN-1) dose-dependently increased NO metabolite in the culture media but had no effect on ADMA. Our results indicate two mechanisms of IL-1beta-induced NO synthesis: the direct stimulation of the expression of iNOS and the indirect stimulation of iNOS activity by upregulating DDAH and reducing ADMA. The ADMA-DDAH system may be another regulatory mechanism of inflammation-mediated NO production for human vascular diseases.