Liver plays a central role in asymmetric dimethylarginine-mediated organ injury

Figure 1 Metabolism and excretion of asymmetric dimethylarginine in the liver. Intracellular asymmetric dimethylarginine (ADMA) is metabolized to citrulline and dimethylamine, a reaction catalyzed by dimethylarginine dimethylaminohydrolase (DDAH). The liver is responsible for the biliary excretion of ADMA. CAT: Cationic amino-acid transporters.

Figure 2 Role of arginine/asymmetric dimethylarginine ratio. Asymmetric dimethylarginine accumulation blocks nitric oxide synthase (NOS) and induces consequent endothelial dysfunction in the vasculature. On the contrary, high arginine levels as substrate for NOS induces vasodilatation. ADMA: Asymmetric dimethylarginine; iNOS: Inducible nitric oxide-synthase; eNOS: Endothelial nitric oxide-synthase; nNOS: Neuronal nitric oxide-synthase.