Acid-base induced alterations in glutamine metabolism and ureogenesis in perfused muscle and liver of the rat.

The effects of altered acid-base balance on the production of urea and the metabolism of glutamine were investigated in the isolated perfused liver and hindquarter of the rat. In the isolated perfused rat liver, lowering of perfusate pH without altering bicarbonate concentration significantly reduced urea production and increased net glutamine synthesis, although the converse did not obtain. In the isolated perfused rat hindquarter when perfusate pH and bicarbonate were simultaneously reduced glutamine synthesis was significantly increased. The combined hepatic and muscle increase in glutamine synthesis accounted for 89% of the decrease in hepatic urea synthesis under these experimental conditions. These changes in nitrogen metabolism are interpreted in terms of adaptations which offset the initial alterations in hydrogen ion homeostasis.