Metabolism of [14C]4-chlorobiphenyl by hepatic microsomes isolated from razorbills, pigeons and rats.
1. Analysis of individual PCB-isomers and congeners in extracts of adipose tissue from N = 12 razorbills suggested that 4-chlorobiphenyl was subjected to metabolism. 2. In vitro metabolism studies using [14C]-4-chlorobiphenyl as substrate showed that razorbills metabolise this substrate to [14C]4-chloro-4'-hydroxybiphenyl at an average rate of 20 pmol/mg microsomal protein/min. For comparison, the metabolism of [14C]-4-chlorobiphenyl by pigeons and rats was also studied, and average rates in the formation of [14C]-4-chloro-4'-hydroxybiphenyl of 12 pmol/mg microsomal protein min and 342 pmol/mg microsomal protein min were estimated. 3. A comparison of the hepatic drug metabolising enzyme system of razorbills and pigeons showed similar concentrations of cytochrome P-450, cytochrome b5 and comparable catalytic activities of cytochrome P-450-dependent monooxygenase, when assessed for HHDN epoxidase, PROD, EROD and the Phase II enzymes glutathiones-S-transferase, but were significantly lower, when compared with rats. The results obtained suggest fundamental differences in the catalytic activities of cytochrome P-450-dependent monooxygenase between avian and mammalian species. 4. The present study, however, provides evidence that fish-eating seabirds have the ability to metabolically dispose of certain PCB isomers and congeners, which are amongst the most ubiquitously distributed pollutants in the ecosystem.
Department of Biochemistry and Physiology, School of Animal and Microbial Sciences, University of Reading, U.K.
J T
JT
Borlakoglu
J P
JP
Wilkins
M P
MP
Quick
C H
CH
Walker
R R
RR
Dils
D000273:Adipose Tissue / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001713:Biphenyl Compounds / Q000378:metabolism* / Q000493:pharmacokinetics; D001717:Birds; D001835:Body Weight / Q000187:drug effects; D002250:Carbon Radioisotopes; D010856:Columbidae; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D008099:Liver / Q000033:anatomy & histology; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology / Q000378:metabolism*; D009929:Organ Size / Q000187:drug effects; D010573:Pesticide Residues / Q000032:analysis / Q000378:metabolism; D011078:Polychlorinated Biphenyls / Q000378:metabolism* / Q000493:pharmacokinetics; D051381:Rats; D011919:Rats, Inbred Strains
D001713:Biphenyl Compounds; D002250:Carbon Radioisotopes; D010573:Pesticide Residues; D003577:Cytochrome P-450 Enzyme System; D011078:Polychlorinated Biphenyls; C006983:4-chlorobiphenyl