US EPA

2160672 

Journal Article 

Abstract 

The influence of pure polychlorinated biphenyl compounds on hepatic function in rat 

Ecobichon, DJ; Johnstone, GJ 

1973 

1 

Toxicology and Applied Pharmacology
ISSN: 0041-008X
EISSN: 1096-0333 

NIOSH/00148712 

25 

3 

440-441 

English 

WOS:A1973Q218800017 

is part of a larger document 3114922 Abstracts of papers for the Twelfth Annual Meeting of the Society of Toxicology, New York, New York March 18–22, 1973

The highly heterogeneous commercial polychlorinated biphenyls (PCB's) have been reported to alter mammalian hepatic function. Are the effects due to the bi phenyl nucleus, the number of chlorine groups per molecule or the position of the chlorine groups on the ring structures? To answer these questions, pure biphenyl and isomerically-pure mono-, di, tetra-, hexa, octa and decachloro biphenyls with known chemical position were injected ip (50 mg/kg/day) into young male Wistar rats (50-60 g) for 3 days, the animals being killed 96 hr after the last injection. The potency of the pure PCB's was compared to that of o,p'- and p,p'-DDT and commercial Aroclors (1254, 1260) administered at the same concentrations. Hepatic function was assessed by pentobarbital sleeping times and in tiitro assays of hepatic microsomal O-demethylase, N-demethylase, aniline hydroxylase, nitro-reductase and carboxylesterase activities and the cytoplasmic bromosulfophthalein (BSP)-glutathione conjugating enzyme system. The biphenyl nucleus played little role since biphenyl caused no induction of hepatic drug-metabolizing enzymes. Monochlorobiphenyl (4-Cl) was without influence; of the di- and tetra- chlorobiphenyls, substitution of chloro groups at the 3 and 4 positions resulted in enhanced induction of microsomal monooxygenases. The more highly chlorinated hexa- and octa- chlorobiphenyls caused an enhanced induction of monooxygenases, though differing little from one another. Nitro-reductase and carboxylesterase activities were not significantly affected by any of the agents whereas all agents, including biphenyl, caused a marked induction of the BSP-conjugating system. 

12th Annual Meeting of the Society of Toxicology 

New York, New York 

Mar 18-22, 1973