NG,NG-dimethyl-L-Arginine dihydrochloride is an endogenous nitric oxide synthase inhibitor. Nitric oxide (NO) that is synthesised from L-arginine contributes to the regulation of blood pressure and to host defence[1].

NG,NG-dimethyl-L-Arginine (ADMA) was found to be able to inhibit macrophage and vascular NO synthase. When added to a cytosolic preparation of macrophage NO synthase, ADMA could cause dose-dependent inhibition of NO formation. In the presence of added arginine, ADMA could inhibited NO synthesis and the inhibitory effects of ADMA were prevented by addition of L-arginine so that the rate of NO synthesis did not significantly differ from control values [1].

Animal study showed that the injection of 1-30 mg/kg ADMA into 3 anaesthetised guineapigs could cause dose-dependent increases in mean arterial blood pressure. Moreover, during continuous infusion of ADMA, which caused plasma ADMA concentrations to rise approximately 9-fold, the systolic blood pressure was raised by nearly 15 % [1].