Effects of sulphydryl reagents on the formation of the aniline metabolite 4-aminophenol and its sulphate and glucuronide conjugates in primary cultures of rat hepatocytes.
1. The effects of various sulphydryl-blocking reagents on aniline biotransformation and cytochrome P-450 levels were studied in cultured rat hepatocytes. 2. Exposure of aniline-metabolizing hepatocytes to p-chloro-mercuribenzoate (PCMB) or p-chloromercuribenzenesulphonic acid (PCMBS) resulted in decreased levels of cytochrome P-450, decreased glucuronidation of 4-aminophenol and increased levels of free 4-aminophenol. 3. Incubation of aniline-metabolizing hepatocytes with disulfiram resulted in decreased formation of 4-aminophenol, but this was not associated with impaired glucuronidation or cytochrome P-450 levels. 4. Exposure of aniline-metabolizing hepatocytes to mersalyl, 2,2'-dithiodipyridine (DTP), 6,6'-carboxydipyridine disulphide (CPDS) or N-ethylmaleimide did not affect the biotransformation of aniline or cytochrome P-450 levels. 5. Metyrapone prevented degradation of cytochrome P-450. Exposure of cells to SKF-525 A inhibited aniline biotransformation without altering cytochrome P-450 levels. 6. PCMB and PCMBS inhibited aniline metabolism, probably by binding to a cysteinyl-SH residue in cytochrome P-450 apoenzyme and 'active sites' of UDP-glucuronyl transferases. Disulfiram inhibited aniline biotransformation, probably indirectly by diminishing NADPH.
Boot
J H
JH
Research Institute of Toxicology (RITOX), University of Utrecht, The Netherlands.
Van Holsteijn
C W
CW
Seinen
W
W
Blaauboer
B J
BJ
D000627:Aminophenols / Q000378:metabolism*; D000814:Aniline Compounds / Q000493:pharmacokinetics*; D000818:Animals; D001711:Biotransformation; D002470:Cell Survival; D002478:Cells, Cultured; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D005965:Glucuronates / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013431:Sulfates / Q000378:metabolism; D013439:Sulfhydryl Reagents / Q000494:pharmacology*
D000627:Aminophenols; D000814:Aniline Compounds; D005965:Glucuronates; D013431:Sulfates; D013439:Sulfhydryl Reagents; D003577:Cytochrome P-450 Enzyme System