1. The effects of acute acid—base alterations on renal ammonia production and glutamine metabolism were studied in anaesthetized dogs.
2. Plasma glutamine rose with acidosis and also when both Pco2 and plasma HCO−3 were raised isohydrically.
3. Blood urea fell when acidosis was induced with hydrochloric acid.
4. The renal production of ammonia per ml of renal blood flow was increased in acidosis, but this was independent of the amount of glutamine delivered to the kidney.
5. The results indicate that acute acidosis affects production of urea and glutamine and increases the capacity of the renal cells to extract glutamine from blood.