PRELIMINARY STUDIES ON METABOLISM AND DISTRIBUTION OF14C LABELED 1,2,7,82TETRACH LORODIBENZO2P2DIOXIN IN COMMON CARP

2,3,7,82 Tetra chlorodibenzo pdioxin(TCDD),an unwanted contaminant of combustion and chlorine bleaching processes,is the most toxic member of the halogenated aromatic hydrocarbons. The disposition and pharmacokinetics of 2,3,7,82 tetra chlorodibenzo pdioxin(TCDD) has been investigated in several species and under various exposure conditions but veryfew studiesare about its metabolites because of its high stability. The distribution profile and metabolism fate of 1,2,7,82 Tetra chloro U2.4Cdibenzodioxin in carp Cyprinus carpio were studied in this paper.1,2,7,82TCDD was dissolved in acetone/corn oil(8/95,v/v) and administrated by a single intraperitoneal injection(i.p,46.4 μ Ci kg-1bodyweight). Liver,bile and visceral fat were sampled at 1,2,4,8,12 days after the exposure and the radioactivities in those sample was assayed by liquid scintillation counter.100mg tissue or 100 μ L bile in little flask was mixed with 0.2mL perchloric acid,0.3mL hydrogen peroxide and was put into a heatingoven 75 ℃for an hour. 10mL scintillation liquid was addedinto the flask immediately after the digest and bleaching procedure. The remanent bile was collected and stored in-80 ℃formetabolite studies.The radioactivity in liver and bile increased in the first 8 days and decrease sequently. The radioactivity in visceral fat washigh obviously in the first 2 days and then decreased. Time course of liver to visceral fat ratio of percent of administered dose exhibited an apparent “S” pattern which shows 1,2,7,82TCDD was transferredfrom visceral fat to liver in the first 8 days. The con2centrations of 1,2,7,82TCDD in various organs sampled at 4 days have much difference:visceral fat > liver > gastrointestinal tract> gonad > kidney > spleen > skin > gill > muscle > brain > blood. Visceral fat,liver,gonad,gastrointestinal tract and muscle werethe main disposition sites of 1,2,7,82TCDD. The metabolites in bile were studied by thin layer chromatogram,radioautographand GC/MS. Various solvent systems had been developed to separate the parent compound and its metabolites. The Ethylacetate/Acetonitrile/Acetic acid (10:2:0.2) is better to separate the metabolites than other solvent systems such asDichloromethane,Hexane/Ethyl acetate (2:1),Ethyl acetate/Aceton/Acetic acid(10:2:0.1) and Acetone/Acetonitrile/Water(4:2:1). The results show that it exists at least 3 kinds of metabolite in bile,and the parent compound identified by GC/MS isonly a small portion of radioactive materials.