title: Citrate does not change uranium chemical speciation in cell culture medium but increases its toxicity and accumulation in NRK-52E cells.
abstract: Uranium (U), as a heavy metal, is a strong chemical toxicant, which induces the damage to proximal tubule kidney cells. In order to reproduce U toxicity in vitro and to avoid precipitation, it is necessary to complex it with a strong ligand such as bicarbonate before dilution with cell culture medium. It was recently shown, in vitro on the NRK-52E normal renal tubular epithelial cells, that citrate increased the toxicity of U(VI)-bicarbonate complexes. This property was attributed to a change in U speciation, characterized by the occurrence of U(VI)-citrate complexes, which were supposed to be more toxic than U(VI)-bicarbonate. Here, we present the results of extended X-ray absorption fine structure spectroscopy (EXAFS) analyses of the media that were used to expose cells in vitro. Resulting data show that even when citrate is added to the exposure medium, the predominant species is U(VI)-bicarbonate. Nonetheless, citrate increases U(VI) toxicity and accelerates its intracellular accumulation kinetics, without inducing precipitation. This study emphasizes another parameter that modulates U(VI) toxicity for renal tubule cells and further characterizes the mechanisms of U(VI) toxicity.
authors.affiliation: Laboratoire Pierre Süe CEA CNRS UMR 9956, CEA Saclay, 91191 Gif sur Yvette, France. marie.carriere@cea.fr
authors.forename: Marie
authors.initials: M
authors.lastname: Carrière
authors.forename: Céline
authors.initials: C
authors.lastname: Thiebault
authors.forename: Sarah
authors.initials: S
authors.lastname: Milgram
authors.forename: Laure
authors.initials: L
authors.lastname: Avoscan
authors.forename: Olivier
authors.initials: O
authors.lastname: Proux
authors.forename: Barbara
authors.initials: B
authors.lastname: Gouget
mesh_terms: D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002951:Citrates / Q000737:chemistry / Q000494:pharmacology*; D003470:Culture Media / Q000032:analysis*; D007687:Kidney Tubules, Proximal / Q000166:cytology; D008855:Microscopy, Electron, Scanning; D008954:Models, Biological; D051381:Rats; D017693:Sodium Bicarbonate / Q000737:chemistry / Q000494:pharmacology; D000077559:Sodium Citrate; D012995:Solubility; D014502:Uranyl Nitrate / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*
chemical_list: D002951:Citrates; D003470:Culture Media; D014502:Uranyl Nitrate; D000077559:Sodium Citrate; D017693:Sodium Bicarbonate