Asymmetric Dimethylarginine Is Increased in Asthma

RATIONALE: Asymmetric dimethylarginine (ADMA) is an endogenous nitric oxide synthase (NOS) inhibitor that competes with L-arginine for binding to NOS. It has been suggested that ADMA contributes to inflammation, collagen deposition, nitrosative stress, and lung function in murine models. OBJECTIVES: To test the hypothesis that ADMA is increased in asthma and that NOS inhibition by ADMA contributes to airways obstruction.