title: High affinity binding site-mediated prevention of chemical absorption across the gastrointestinal tract.
abstract: Preventing mucosal absorption of low-molecular weight compounds such as carcinogens, toxins and drugs could help prevent many diseases. To characterize the effects of dose and timing on high-affinity binding site mediated sequestration of specific chemical ligands in the gastrointestinal tract, avidin was perorally-administered to mice either prior to or mixed with 3H-biotin. Avidin enhanced fecal 3H-biotin excretion in a dose-dependent manner, consistent with the accepted mechanism of egg white-induced biotin deficiency syndrome. Avidin administration up to 4 h before 3H-biotin administration also enhanced fecal 3H-biotin excretion. Activated charcoal (AC) reduced 3H-biotin absorption when mixed with 3H-biotin before ingestion, but was ineffective when ingested prior to 3H-biotin. These studies suggest that ingestion of high-affinity protein binding sites can establish an absorptive barrier at the gastrointestinal mucosa to prevent the uptake of unwanted low molecular-weight chemicals.
authors.affiliation: Department of Animal Science, University of Connecticut, Center for Environmental Health, CANR, Box U-39, 3636 Horsebarn Road Extension, Storrs, CT 06269, USA.
authors.forename: M V
authors.initials: MV
authors.lastname: Rasmussen
authors.forename: T T
authors.initials: TT
authors.lastname: Barker
authors.forename: L K
authors.initials: LK
authors.lastname: Silbart
mesh_terms: D000818:Animals; D001360:Avidin / Q000494:pharmacology; D001665:Binding Sites; D001710:Biotin / Q000493:pharmacokinetics*; D002606:Charcoal / Q000494:pharmacology; D005260:Female; D005818:Genetic Engineering; D007408:Intestinal Absorption; D051379:Mice; D008807:Mice, Inbred BALB C; D008970:Molecular Weight; D011485:Protein Binding
chemical_list: D001360:Avidin; D002606:Charcoal; D001710:Biotin