Metabolism of acetaminophen by cultured rat hepatocytes. Depletion of protein thiol groups without any loss of viability.
Over the course of 4 hr, the metabolism of acetaminophen (APAP) by cultured rat hepatocytes resulted in a depletion of protein thiols and an accumulation of oxidized glutathione (GSSG) in the medium. With 20 mM APAP, arylation and the formation of glutathione mixed disulfides accounted for a loss of 22% of the total protein thiols in the absence of any loss of viability. With 20 mM APAP and an inhibition of glutathione reductase by 1.3-(2-chloroethyl)-1-nitrosourea (BCNU), protein thiols were depleted by 40% by arylation and the formation of glutathione mixed disulfides, again without a loss of viability. With 20 mM APAP and BCNU in the presence of 20 mM deferoxamine, there was still little or no cell killing after 8 hr despite a loss now of almost 60% of the total protein thiols. These data do not support the hypothesis that a depletion of protein thiols is related to the toxicity of APAP. One millimolar APAP and BCNU killed 60% of the hepatocytes within 4 hr. In this circumstance, the loss of protein thiols was not attributable to either arylation by APAP metabolites or the formation of glutathione mixed disulfides. The antioxidant N,N'-diphenyl-phenylenediamine prevented the cell killing and the loss of protein thiols, a result implicating a role for lipid peroxidation in the depletion of protein-bound thiols. However, protein thiol depletion under these circumstances is not necessarily related to the lethal cell injury and most likely represents an epiphenomenon of the peroxidation of cellular lipids.
Department of Pathology, Thomas Jefferson University, Philadelphia, PA 19107.
M E
ME
Kyle
I
I
Sakaida
A
A
Serroni
J L
JL
Farber
D000082:Acetaminophen / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D002330:Carmustine / Q000378:metabolism / Q000494:pharmacology; D002478:Cells, Cultured; D003676:Deferoxamine / Q000494:pharmacology; D005978:Glutathione / Q000031:analogs & derivatives / Q000378:metabolism; D019803:Glutathione Disulfide; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D010655:Phenylenediamines / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013438:Sulfhydryl Compounds / Q000378:metabolism*
D010655:Phenylenediamines; D011506:Proteins; D013438:Sulfhydryl Compounds; D000082:Acetaminophen; C004845:N,N'-diphenyl-4-phenylenediamine; D005978:Glutathione; D003676:Deferoxamine; D002330:Carmustine; D019803:Glutathione Disulfide