Effects of infusions of ammonia, amides, and amino acids on excretion of ammonia

¹ Department of Physiology, Cornell University Medical College, New York City

Ammonium lactate and a variety of amides and amino acids were infused into one renal artery of anesthetized dogs in acidosis. Urine was collected separately from the two kidneys and rates of excretion of ammonia on the two sides were compared. The infusion of ammonium lactate resulted in a prompt increase in ammonia excretion restricted to the side infused. As much as 50% of the infused ammonia appeared as excess ammonia in the urine. The infusion of glutamine, asparagine, alanine, glycine, leucine, and glutamic acid induced bilateral increases in rates of ammonia excretion, commonly greater on the side infused. However, ammonia excretion increased significantly on the side contralateral to that infused. A much smaller fraction of the infused nitrogen appeared as urinary ammonia than when ammonium lactate was infused. The infusion of valine induced no increase in ammonia excretion by either kidney; rather, ammonia excretion was reduced. The significance of these results in relation to the study of renal metabolism of N¹⁵ compounds is discussed.