Possible Interaction: Ammonia and Ornithine

“Results:Plasma ammonia concentrations just after exhaustion and at 15 min after exhaustion were significantly more with ornithine ingestion than with placebo.”

“ Ammonia also modulates BBB transport of the cationic amino acids: the nitric oxide precursor, arginine, and ornithine , which is an ammonia trap, and affects the transport of energy metabolites glucose and creatine.”

“It has been shown in vitro, in vivo and in perfused organs that urea synthesis from ammonia is limited by endogenous ornithine and that ornithine can pharmacologically promote urea formation to a greater degree than any ammonia supply.”

“Adding arginine, citrulline, and ornithine to EAA for a further four days significantly lowered the mean serum ammonia level.”

“From these … conclude that ammonia , a direct substrate for urea synthesis, … control the concentrations of both ornithine and acetylglutamate in the liver, directly or indirectly, although perfused liver lacks some factors that keep … concentration of ornithine at the in vivo level and cause its increase in response to ammonia.”

“ Blood ammonia rose with ornithine load , while ornithine levels were twice that of controls.”

“The data indicate an increased detoxification rate of ammonia by arginine and ornithine supplementation.”

“We also observed that the combination of hyperammonemia with ornithine resulted in significant decreases of sulfhydryl levels, reduced glutathione (GSH) concentrations and the activities of catalase (CAT) and glutathione peroxidase (GPx), highlighting a synergistic effect of ornithine and ammonia.”

“The amount of reduction in blood ammonia by ornithine and arginine compounds was less the longer the preinfusion of NH4.”

“The concentration of ornithine rather than that of carbamoyl phosphate or the activity of the enzymes involved, may represent a limiting factor controlling both the flux of ammonia in the urea cycle and the availability of mitochondrial carbamoyl phosphate for orotic acid synthesis.”