title: Cadmium chloride inhibits lactate gluconeogenesis in isolated human renal proximal tubules: a cellular metabolomic approach with 13C-NMR.
abstract: As part of a study on cadmium nephrotoxicity, we studied the effect of cadmium chloride (CdCl2) in isolated human renal proximal tubules metabolizing the physiological substrate lactate. Dose-effect experiments showed that 10-500 μM CdCl2 reduced lactate removal, glucose production and the cellular levels of ATP, coenzyme A, acetyl-coenzyme A and of reduced glutathione in a dose-dependent manner. After incubation with 5 mM L: -[1-(13)C]-, or L: -[2-(13)C]-, or L: -[3-(13)C] lactate or 5 mM L: -lactate plus 25 mM NaH(13)CO3 as substrates, substrate utilization and product formation were measured by both enzymatic and carbon 13 NMR methods. Combination of enzymatic and NMR measurements with a mathematical model of lactate metabolism previously validated showed that 100 μM CdCl2 caused an inhibition of flux through lactate dehydrogenase and alanine aminotransferase and through the entire gluconeogenic pathway; fluxes were diminished by 19% (lactate dehydrogenase), 28% (alanine aminotransferase), 28% (pyruvate carboxylase), 42% (phosphoenolpyruvate carboxykinase), and 52% (glucose-6-phosphatase). Such effects occurred without altering the oxidation of the lactate carbons or fluxes through enzymes of the tricarboxylic acid cycle despite a large fall of the cellular ATP level, a marker of the energy status and of the viability of the renal cells. These results that were observed at clinically relevant tissue concentrations of cadmium provide a biochemical basis for a better understanding of the cellular mechanism of cadmium-induced renal proximal tubulopathy in humans chronically exposed to cadmium.
authors.affiliation: Faculté de Médecine Laennec, INSERM Unit # 820 (Metabolomics and Metabolic Diseases), Rue G. Paradin, 69372, Lyon Cedex 08, France.
authors.forename: Hassan
authors.initials: H
authors.lastname: Faiz
authors.forename: Agnès
authors.initials: A
authors.lastname: Conjard-Duplany
authors.forename: Michelle
authors.initials: M
authors.lastname: Boghossian
authors.forename: Guy
authors.initials: G
authors.lastname: Martin
authors.forename: Gabriel
authors.initials: G
authors.lastname: Baverel
authors.forename: Bernard
authors.initials: B
authors.lastname: Ferrier
mesh_terms: D019256:Cadmium Chloride / Q000493:pharmacokinetics / Q000633:toxicity*; D002247:Carbon Isotopes; D003627:Data Interpretation, Statistical; D004305:Dose-Response Relationship, Drug; D004785:Environmental Pollutants / Q000493:pharmacokinetics / Q000633:toxicity*; D005943:Gluconeogenesis / Q000187:drug effects*; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D007773:Lactates / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D055432:Metabolomics / Q000379:methods*; D046509:Tissue Culture Techniques
chemical_list: D002247:Carbon Isotopes; D004785:Environmental Pollutants; D007773:Lactates; D019256:Cadmium Chloride