Urea cycle regulation: I. Coupling of ornithine metabolism to mitochondrial oxidative phosphorylation
Stumpf, D.A.; Parks, J.K.
Neurology 30(2): 178-183
1980
ISSN/ISBN: 0028-3878 PMID: 7188796 Document Number: 157780
Ornithine metabolism is coupled to oxidative phosphorylation in isolated rat liver mitochondria. The pathway involving ornithine:.alpha.-ketoglutarate transaminase (OKT), glutamic semialdehyde dehydrogenase (GSDH), and glutamate dehydrogenase (GDH) with cycling of .alpha.-ketoglutarate-glutamate at the OKT reaction appears to be involved. Ornithine may be utilized by this pathway to sustain ATP levels during mitochondrial energy-deficiency states with resultant decreased urea-cycle flux and increased ammonia production. This pathophysiologic mechanism suggests that hyperammonemia is a consequence of an energy-deficiency state. Therapy directed toward alleviating the energy-deficiency state may be more beneficial than efforts to reduce ammonia levels.