title: Dose-dependent effects on tissue distribution and metabolism of dimethylarsinic acid in the mouse after intravenous administration.
abstract: Most mammals methylate inorganic arsenic to dimethylarsinic acid (DMA). This organic arsenical causes organ-specific toxicity and is a multi-organ tumor promoter. The objective of this study was to examine whether dose could affect the distribution and metabolism of DMA. Female B6C3F1 mice (3-4/time point) were administered 1.11 or 111 mg/kg of DMA (1 microCi of [14C] or unlabeled) intravenously and killed serially (5-480 min). Blood was separated into plasma and red blood cell fractions and liver, kidney and lung were removed, weighed and homogenized. Tissue samples were oxidized and analyzed for DMA-derived radioactivity. Blood and several organs of the non-radioactive DMA-treated animals were digested in acid and analyzed by hydride generation atomic absorption spectrophotometry for DMA and metabolites. Concentration-time profiles showed a biexponential decrease of DMA-derived radioactivity in all tissues examined. Kidney had the highest concentration (1-20% dose/gm) of radioactivity of all tissues up to 60 min post-administration. Concentration of radioactivity was greater in plasma than red blood cells at 5 and 15 min and then was similar for the remaining time points. A dose-dependent effect on the concentration of radioactivity was observed in the lung. The retention of radioactivity in the lung was altered compared with liver and kidney, with a much longer t1/2beta and a disproportionate increase in area under the curve with increased dose. No methylated or demethylated products of DMA were detected in blood or any organ up to 8 h post-exposure. The dose-dependent distribution of DMA in the lung may have a role in the toxic effects DMA elicits in this organ.
authors.affiliation: U.S. Environmental Protection Agency, Experimental Toxicology Division, Research Triangle Park, NC 27711, USA. hughes.michaelf@epamail.epa.gov
authors.forename: M F
authors.initials: MF
authors.lastname: Hughes
authors.forename: L M
authors.initials: LM
authors.lastname: Del Razo
authors.forename: E M
authors.initials: EM
authors.lastname: Kenyon
mesh_terms: D000818:Animals; D019540:Area Under Curve; D001151:Arsenic / Q000378:metabolism; D002101:Cacodylic Acid / Q000008:administration & dosage / Q000378:metabolism / Q000493:pharmacokinetics*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006207:Half-Life; D007275:Injections, Intravenous; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008168:Lung / Q000378:metabolism; D051379:Mice; D008815:Mice, Inbred Strains; D009928:Organ Specificity; D014018:Tissue Distribution
chemical_list: D002101:Cacodylic Acid; D001151:Arsenic