Specificity and metal sensitivity of renal amino acid transport

Abstract

1. 1. This study describe some properties of amino acid transport systems at the peritubular cell membrane in rabbit kidneys, and compares them with characteristics of amino acid uptake at the luminal membrane. 2. 2. Mutual inhibition studies led to the conclusion that at least four separate systems are involved in transport of l-amino acids at the peritubular membrane. These four systems, defined on the basis of their substrate specificities mediate uptake, respectively, of (a) dicarboxylic amino acids, (b) phenylalanine, (c) alanine, serine, cysteine, glycine, and (d) basic amino acids. 3. 3. In their structural specificity peritubular systems resemble those responsible for amino acid reabsorption at the luminal cell membrane. In contrast to luminal transport of dicarboxylic compounds, however, their peritubular uptake is inhibited by low concentrations of Hg; movement of other amino acids is not affected. Similarly, a peritubular action of Cd was observed, specific for aspartic and glutamic acids.