Effect of Infusion of Single Amino Acids Upon Excretion of Other Amino Acids

Abstract

In dogs the infusion of amino acids resulted in a many-fold increase in the rate of excretion of 7 other amino acids. The ratio of the exptl. to the control excretion varied widely, depending upon the amino acid infused and the amino acid excreted. In general, the excretion of an amino acid was most increased by the infusion of an amino acid of similar acidic properties. However, some specific effects, not obviously related to the acidity of the amino acid, were noted. Of the amino acids infused, neutral amino acids, glutamine, and asparagine were the most effective; the dicarboxylic acids least. The excretion of threonine and histidine was, in general, most affected. The excretion of glutamine and aspartic acids does not fall into the above mentioned patterns, but varies with specific amino acids rather than amino acid groups. The excretion of glutamic and aspartic acid was dramatically increased by the infusion of alanine. While glutamic acid markedly increased the excretion of aspartic acid, aspartate infusion had relatively little effect upon glutamic acid excretion. The excretion of glutamic acid was also enhanced by the infusion of asparagine and histidine, while the excretion of aspartic acid was increased by glutamine. In several instances the excretion of glutamic and aspartic acids was considerably greater than could be accounted for on the basis of inhibition of renal tubular reabsorption by the infused amino acid. The implications of these findings are discussed.