title: Developmental aspects of maleic acid-induced inhibition of sugar and amino acid transport in the rat renal tubule.
abstract: The transport of alpha-aminoisobutyric acid and alpha-methyl-d-glucoside by isolated tubules from Sprague-Dawley rats at different stages of development follows a separate age-dependent pattern for each substrate. The effects of 6 M maleic acid on transport processes differ for amino acids and sugars and become manifest at distinct points during development. Maximum inhibition by maleic acid occurs at a time subsequent to maturity of these transport systems. In an effort to explain these transport phenomena, the uptake and metabolism of 14C-labeled maleic acid by the newborn or adult renal tubule was studied, showing significant binding by the tubule membrane, penetration of the cell by diffusion, and no conversion to 14CO2. Maleic acid has no demonstrable effect on the membrane-associated enzymes which are thought to play a role in the transport of small molecules.
mesh_terms: D000367:Age Factors; D000596:Amino Acids / Q000502:physiology*; D000621:Aminoisobutyric Acids / Q000502:physiology; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002241:Carbohydrates / Q000502:physiology*; D005260:Female; D066298:In Vitro Techniques; D007684:Kidney Tubules / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008298:Maleates / Q000494:pharmacology* / Q000502:physiology; D008757:Methylglucosides / Q000502:physiology; D051381:Rats
chemical_list: D000596:Amino Acids; D000621:Aminoisobutyric Acids; D002241:Carbohydrates; D008298:Maleates; D008757:Methylglucosides