Determination of arginine and methylated arginines in human plasma by liquid chromatography–tandem mass spectrometry

Nitric oxide (NO) is synthesized from L-arginine (ARG) catalyzed by the enzyme nitric oxide synthase (NOS) and is important in the regulation of vascular tone, neurotransmission and host defense. N,N-Dimethyl L-arginine (asymmetric dimethylarginine, ADMA) and N-monomethyl L-arginine (MMA) are endogenous inhibitors of NOS. N,N'-Dimethyl L-arginine (symmetric dimethylarginine, SDMA), the inactive enantiomer of ADMA is also known to be present...