Maleic acid-induced inhibition of amino acid transport in rat kidney

Abstract

The previously reported deleterious effects of the administration of maleic acid in vivo on renal amino acid transport have been extended to studies in vitro in which maleic acid markedly inhibited amino acid uptake by kidney-cortex slices. This inhibition has been observed at concentrations which approximate those obtained in vivo and is due to accelerated efflux and imparied influx of amino acids in kidney cells. The results showed that maleate does not compete for a common transport site with amino acids but rather suggested that it alters renal tubular transport by interfering with intracellular processes essential to active amino acid transport. The studies failed to support previous investigations relating the mechanism of maleate action to the binding of free thiol groups. The specificity of the toxic effects of maleic acid for renal transport systems was shown to be due, at least in part, to its ability to penetrate kidney cells, and its failure to enter muscle of intestinal cells.