Long-term regulation of hepatic glutaminase and the urea cycle enzymes

Glutamine is not a dietary essential amino acid, but it does play an important role within the body, and recent developments in the treatment of several pathological states have resulted in the provision of large amounts of dietary glutamine, either enterally or parenterally.¹³ A major fate of glutamine within the body is catabolism via the hepatic pathways of gluconeogenesis and urea synthesis. This review focuses on the long-term regulation of glutamine catabolism within the liver through changes in the activities of phosphate-activated glutaminase and the urea cycle enzymes.