Renal reabsorption of amino acids

Abstract

Using the method of stop flow analysis an attempt was made to localize the process of amino acid reabsorption in the nephron of the dog. Special attention was given to the group of basic amino acids and cystine believed to share a common tubular transport mechanism. The evidence obtained in this study points clearly to the proximal segment as the site of intensive reabsorption of all amino acids investigated. During the infusion of arginine, lysine or ornithine, an increased excretion of two remaining basic amino acids plus cystine was observed, as a rule. Successful attempts were made to infuse cystine intravenously. The results of these experiments did provide the missing link for the hypothesis derived by Dent and Rose (Quart. J. Med. 20: 205, 1951) concerning the common transport mechanism of arginine, ornithine, lysine, and cystine in the renal tubules. The functional cystinuria, which can be induced by saturating the common reabsorptive pathway with each of the above-mentioned amino acids, is fully reversible.