From Arginine to Greatine: Regional and Cellular Gene Expression of Enzymes and Transporters Linking Nitrogen and Energy Metabolism In Brain

摘要

Arginine, a semiessential amino acid, is provided to the organism by protein intake and newly synthesized from citralline, in the kidney. In the liver and intestine it is the final useful product of the urea cycle. Arginine is a substrate for different metabolic pathways (Fig. 1), including the synthesis of nitric oxide, ornithine, creatine, and creatine phosphate, which, in the presence of the creatine kinase isozymes, function as an energy buffer and for channeling energy-rich phosphates between the mitochondrion and the cytosol. Metabolic schemes do not usually identify the organs in which enzymes and transporters are expressed. Some recent reviews have given an overview of our knowledge on this (1,2), and metabolite exchange between organs has been investigated.