title: L-alanine accumulation in isolated tubuli from rat kidney cortex.
abstract: Tubuli were prepared from rat renal cortex by modification of the method adopted from HOWARD and PESCH (J.Biol. Chem. 243, 3105, 1968). At 37 degrees C tubuli showed constant pyruvate consumption and glucose production for more than one hour. Intracellular electrolyte and amino acid concentrations were measured after separating the tubuli from the incubation medium by a layer of silicon oil in 5 seconds. During incubation at 37 degrees C L-alanine was accumulated 2.6 fold in the tubuli, while intracellular Na+ concentration dropped to about 50 mEq/l. At 27 degrees C, when pyruvate consumption and glucose production was reduced to less than half compared with 37 degrees C incubation, the respective gradients were higher. L-alanine accumulation was reduced by 2,4-dinitrophenol, antimycin A, ouabain and p-hydroxymercuribenzoate and was completely abolished by the reversal of the Na+ concentration gradient between extracellular and intracellular spaces. At 4 degrees C, when erergy production in tubuli ceased, L-alanine could be concentrated in the case of a Na+o/Na+i ratio greater than unity but not at a lower ratio. It is concluded that the accumulation of L-alanine is a direct function of the energy provided by the Na+ concentration gradient and is mediated by a postulated carrier, which can be injured by sulfhydryl group reagents like p-hydroxymercuribenzoate.
mesh_terms: D000409:Alanine / Q000378:metabolism*; D000818:Animals; D000968:Antimycin A / Q000494:pharmacology; D001692:Biological Transport; D004140:Dinitrophenols / Q000494:pharmacology; D066298:In Vitro Techniques; D007672:Kidney Cortex / Q000378:metabolism*; D007684:Kidney Tubules / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D010042:Ouabain / Q000494:pharmacology; D010477:Perfusion; D010695:Phlorhizin / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D011773:Pyruvates / Q000378:metabolism; D051381:Rats; D012964:Sodium / Q000378:metabolism; D013696:Temperature
chemical_list: D004140:Dinitrophenols; D011773:Pyruvates; D010042:Ouabain; D000968:Antimycin A; D012964:Sodium; D010695:Phlorhizin; D000409:Alanine; D011188:Potassium