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.
Borlakoglu
J T
JT
Department of Biochemistry and Physiology, School of Animal and Microbial Sciences, University of Reading, U.K.
Wilkins
J P
JP
Quick
M P
MP
Walker
C H
CH
Dils
R R
RR
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