title: Tissue distribution, metabolism, and excretion of 14C-TCDD in a TCDD-susceptible and a TCDD-resistant rat strain.
abstract: A comparative study was carried out in the most TCDD-resistant [Han/Wistar (H/W), LD50 greater than 3000 micrograms/kg] and the most TCDD-susceptible [Long-Evans (L-E), LD50 about 10 micrograms/kg] rat strain to assess the significance of kinetic factors in TCDD toxicity. Young adult males of both strains were administered 5 micrograms/kg (1.9 microCi/kg) 14C-TCDD intraperitoneally. Four rats per strain were killed at 4 hr, 1, 4, 8, 16, and 32 days after exposure. A total of 22 tissues along with blood and serum were sampled for liquid scintillation counting. From half of the animals, daily urine and faeces were also analyzed. In addition, 3 rats per strain were given 50 micrograms/kg (19 microCi/kg) 14C-TCDD and prepared for whole-body autoradiography after 1, 4 or 8 days. The livers of two rats per strain killed at 4 hr, 4 or 16 days, and the excreta from two rats of both strains collected on days 1-4, 5-8, 13-16, and 29-32 after exposure were analyzed for metabolites of TCDD by high pressure liquid chromatography. The label was mainly excreted in faeces as metabolites of TCDD, and the half-life of elimination was 20.8 (L-E) or 21.9 (H/W) days. A very similar overall distribution pattern was observed in both strains irrespective of dose, and the liver was the major site of accumulation. Practically all liver 14C-activity was found as the parent compound. Moderate strain-related differences were observed in the thyroid, thymus, prostate, adrenals, and brown and white fat, where lower values were recorded in H/W rats.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Environmental Hygiene and Toxicology, National Public Health Institute, Kuopio, Finland.
authors.forename: R
authors.initials: R
authors.lastname: Pohjanvirta
authors.forename: T
authors.initials: T
authors.lastname: Vartiainen
authors.forename: A
authors.initials: A
authors.lastname: Uusi-Rauva
authors.forename: J
authors.initials: J
authors.lastname: Mönkkönen
authors.forename: J
authors.initials: J
authors.lastname: Tuomisto
mesh_terms: D000273:Adipose Tissue / Q000032:analysis / Q000378:metabolism; D000818:Animals; D001345:Autoradiography; D001711:Biotransformation; D001835:Body Weight / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D004147:Dioxins / Q000493:pharmacokinetics*; D004351:Drug Resistance; D005243:Feces / Q000032:analysis; D008297:Male; D000072317:Polychlorinated Dibenzodioxins / Q000378:metabolism / Q000493:pharmacokinetics*; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution
chemical_list: D004147:Dioxins; D000072317:Polychlorinated Dibenzodioxins