Time dependence of chloroform-induced metabolic alterations in the liver and kidney of B6C3F1 mice.
The time course of some biochemical changes in the liver and in the kidney was studied in B6C3F1 male mice dosed with a single i.p. injection of 150 mg/kg body weight (b.w.) CHCl(3). Hepatic and renal microsomal cytochrome P450 (P450) content and some related monooxygenase activities, CHCl(3) oxidative and reductive metabolism, cytosolic reduced glutathione (GSH) content and serum markers of nephrotoxicity were measured. In the liver no biochemical changes were produced up to a week after chloroform treatment. On the contrary, the drug-metabolizing enzyme system in the kidney was dramatically and rapidly inactivated by chloroform treatment. Maximum loss of GSH (50%), P450 (80%) and of different enzymatic activities, including CHCl(3) bioactivation, occurred during the first 5 h. These biochemical alterations are early effects, not secondary to morphological tissue changes. Kidney parameters, altered by chloroform treatment, returned to control values at different times: renal function markers became normal in 48 h; GSH levels were recovered at 96 h and the drug-metabolizing enzyme activities at longer times. The present results clearly show that repeated daily doses of chloroform, as those used in carcinogenicity tests, find renal tubular cells not at their physiological status, due to the changes produced by the first chloroform dose. Therefore the similarity in P450-dependent chloroform metabolism shown in vitro by hepatic and renal microsomes from untreated B6C3F1 male mice or in vivo in animals treated once, is lost during repeated treatments. These features should be considered in understanding the different susceptibility of the liver and the kidney to chloroform-induced tumours.
Rossi
S
S
Istituto Superiore di Sanità, Comparative Toxicology and Ecotoxicology Laboratory, Viale Regina Elena 299-00161, Rome, Italy.
Gemma
S
S
Fabrizi
L
L
Testai
E
E
Vittozzi
L
L
D000815:Aniline Hydroxylase / Q000378:metabolism; D000818:Animals; D001806:Blood Urea Nitrogen; D002725:Chloroform / Q000633:toxicity*; D003404:Creatinine / Q000097:blood; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism; D019362:Cytochrome P-450 CYP2B1 / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D015786:Cytochromes b5 / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism*; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D013997:Time Factors
D010743:Phospholipids; D002725:Chloroform; D015786:Cytochromes b5; D003577:Cytochrome P-450 Enzyme System; D003404:Creatinine; D000815:Aniline Hydroxylase; D019363:Cytochrome P-450 CYP1A1; D019362:Cytochrome P-450 CYP2B1; D005978:Glutathione