ADMA-Arginine

Nitric oxide (NO which is formed in the vascular endothelium plays a crucial role in the regulation of vascular structure and function. NO has been named an “endogenous anti-atherogenic molecule” due to its diverse regulatory functions in vascular homeostasis.

NO is formed by the enzyme NO synthase (NOS) from the amino acid precursor L-arginine. NOS activity is inhibited by asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NOS.

The effects of ADMA on NO synthesis and NO-mediated pathophysiological processes have been described in numerous experimental and clinical studies, including patients with hypercholesterolemia, hypertension, chronic heart failure, chronic renal failure and other internal disorders.

Elevated ADMA levels are a risk factor for future cardiovascular events and total mortality, as evidenced by prospective clinical studies comprising more than 10,000 participants. Thus, ADMA has diagnostic relevance as a novel cardiovascular risk marker.

Importantly, high ADMA levels and low L-arginine/ADMA ratio were both independent predictors of death in the community-based Framingham Offspring Study. As ADMA competes with L-arginine for binding to NO synthase, many scientists suggest that the L-arginine/ADMA ratio is a better index of NOS substrate availability and, thus, functional integrity of the NOS pathway, than L-arginine levels alone. Furthermore the measurement of both L-arginine and ADMA plasma concentrations is suitable for treatment surveillance of subjects during nutritional Larginine supplementation.

The competitive ADMA-Arginine ELISA uses the microtiter plate format. Antigen is bound to the solid phase of the microtiter plate. Antigen in the samples is acylated and competes with solid phase bound antigen for a fixed number of antiserum binding sites. When the system is in equilibrium, free antigen and free antigen-antiserum complexes are removed by washing. The antibody bound to the solid phase ADMA and Arginine, respectively are detected by anti-rabbit/peroxidase. The substrate TMB / peroxidase reaction is monitored at 450 nm. The amount of antibody bound to the solid phase antigen is inversely proportional to the antigen concentration of the sample.

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