title: The influence of complexing agents on the solubility and absorption of aluminium in rats exposed to aluminium in water.
abstract: The influence of citrate (0-31 mM), fluoride (0 or 2.6 mM) and silicate (0 or 2.6 mM) on the absorption of Al (0-18 mM) was studied in rats. We tested the hypothesis that the solubility and absorption of Al increases in the gastrointestinal (GI) tract in the presence of the complexing agents. Male rats were exposed for 6 or 7 weeks to soluble Al in acidic drinking water (pH 2.5-3.0) with or without the complexing agents. At the end of exposure Al was fractionated in the stomach content, in order to study if the solubility of Al was changed after ingestion. Al absorption was estimated by Al analysis of the right femur bone. Speciation calculations indicated that citrate and fluoride caused formation of soluble Al-citrate (97%) and -fluoride (> 60%) complexes in the water. Silicate did not affect the theoretical speciation. In all cases, a large fraction of soluble Al became insoluble in the stomach after ingestion. The concentration of soluble Al increased only in the presence of citrate or a mixture of fluoride and silicate, but citrate was the only complexing agent that influenced the absorption of Al in the rat. This indicates that the form of Al may be changed in the GI tract when soluble drinking-water Al is ingested, and that the solubility of Al in drinking water and GI tract may not be good predictors of the bioavailability of Al even when chelating agents are present.
authors.affiliation: Swedish National Food Administration, and Department of Environmental Toxicology, Uppsala University. glwi@slv.se
authors.forename: A W
authors.initials: AW
authors.lastname: Glynn
authors.forename: A
authors.initials: A
authors.lastname: Sparén
authors.forename: L G
authors.initials: LG
authors.lastname: Danielsson
authors.forename: B
authors.initials: B
authors.lastname: Sundström
authors.forename: L
authors.initials: L
authors.lastname: Jorhem
mesh_terms: D017607:Aluminum Compounds / Q000493:pharmacokinetics*; D000818:Animals; D001682:Biological Availability; D001835:Body Weight / Q000187:drug effects; D001842:Bone and Bones / Q000378:metabolism; D004326:Drinking; D004435:Eating; D005753:Gastric Mucosa / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007408:Intestinal Absorption; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012995:Solubility; D014874:Water Pollutants, Chemical / Q000493:pharmacokinetics*
chemical_list: D017607:Aluminum Compounds; D014874:Water Pollutants, Chemical