Back to Search
Start Over
Inhibition of Carbamyl Phosphate Synthetase-I and Glutamine Synthetase by Hepatotoxic Doses of Acetaminophen in Mice
- Source :
- Toxicology and Applied Pharmacology. 146:317-327
- Publication Year :
- 1997
- Publisher :
- Elsevier BV, 1997.
-
Abstract
- The primary mechanisms proposed for acetaminophen-induced hepatic necrosis should deplete protein thiols, either by covalent binding and thioether formation or by oxidative reactions such as S-thiolations. However, in previous studies we did not detect significant losses of protein thiol contents in response to administration of hepatotoxic doses of acetaminophen in vivo. In the present study we employed derivatization with the thiol-specific agent monobromobimane and separation of proteins by SDS–PAGE to investigate the possible loss of specific protein thiols during the course of acetaminophen-induced hepatic necrosis. Fasted adult male mice were given acetaminophen, and protein thiol status was examined subsequently in subcellular fractions isolated by differential centrifugation. No decreases in protein thiol contents were indicated, with the exception of a marked decrease in the fluorescent intensity, but not of protein content, as indicated by staining with Coomassie blue, of a single band of approximately 130 kDa in the mitochondrial fractions of acetaminophen-treated mice. This protein was identified by isolation and N-terminal sequence analysis as carbamyl phosphate synthetase-I (CPS-I) (EC 6.3.4.16). Hepatic CPS-I activities were decreased in mice given hepatotoxic doses of acetaminophen. In addition, hepatic glutamine synthetase activities were lower, and plasma ammonia levels were elevated in mice given hepatotoxic doses of acetaminophen. The observed hyperammonemia may contribute to the adverse effects of toxic doses of acetaminophen, and elucidation of the specific mechanisms responsible for the hyperammonemia may prove to be useful clinically. However, the preferential depletion of protein thiol content of a mitochondrial protein by chemically reactive metabolites generated in the endoplasmic reticulum presents a challenging and potentially informative mechanistic question.
- Subjects :
- Male
Molecular Sequence Data
Carbamoyl-Phosphate Synthase (Ammonia)
Mitochondria, Liver
Oxidative phosphorylation
Carbamyl Phosphate
Cell Fractionation
Toxicology
Article
Bridged Bicyclo Compounds
Mice
Ammonia
Glutamine synthetase
medicine
Animals
Amino Acid Sequence
Sulfhydryl Compounds
Acetaminophen
Fluorescent Dyes
Pharmacology
chemistry.chemical_classification
Dose-Response Relationship, Drug
Endoplasmic reticulum
Sulfhydryl Reagents
Alanine Transaminase
Hyperammonemia
Analgesics, Non-Narcotic
medicine.disease
Enzyme
Liver
chemistry
Biochemistry
Thiol
Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing)
Electrophoresis, Polyacrylamide Gel
medicine.drug
Subjects
Details
- ISSN :
- 0041008X
- Volume :
- 146
- Database :
- OpenAIRE
- Journal :
- Toxicology and Applied Pharmacology
- Accession number :
- edsair.doi.dedup.....a7a595c053e8e3148d634df6bbe4c9fc
- Full Text :
- https://doi.org/10.1006/taap.1997.8228