The Renal Regulation of Acid Base Balance with Special Reference to the Mechanism for Acidifying the Urine

Abstract

60% of urinary NH3 comes from plasma glutamine and 40% from plasma amino acids. The kidney contains an enzyme, glutaminase, which splits off the amide N2 of glutamine to form glutamic acid and NH3. Renal amino acid oxidase causes oxidative deamina-tion of amino acids to corresponding keto acids and NH3. To acidify urine H2CO3 may react with Na2HPO4 to form NaH2PO4 and NaHCO3. The base is resorbed. In expts. on 2 unanesthetized dogs the urine was showed to be acidified by addition of acid through some type of tubular secretory mechanism. The details are considered in the "tubular ionic exchange theory.".