title: Oxidant-increased proteolysis in rat liver slices: effect of bromotrichloromethane, antioxidants and effectors of proteolysis.
abstract: Proteolysis and lipid peroxidation were evaluated in rat liver slices incubated in the presence of the oxidant bromotrichloromethane and effectors of proteolysis. Proteolysis was evaluated by S-amino acids and lipid peroxidation by thiobarbituric acid-reactive substances (TBARS) released into the incubation medium. The increased release of S-amino acids by BrCl3C depended on incubation time and oxidant concentration. S-Amino acid release increased 30% over control value and TBARS increased from 22 to 124 nmol/g liver by incubation for 120 min with 1 mM BrCl3C. Release of S-amino acids and TBARS was decreased when liver slices were treated with nor-dihydroguaiaretic acid (NDG), butylated hydroxyanisole (BHA), Trolox C, or N,N'-diphenyl-1,4-phenylenediamine (DPPD) immediately prior to addition of oxidant, suggesting participation of lipid-soluble free radicals. Oxidant-induced release of S-amino acids but not of TBARS was decreased by mannitol, suggesting participation of hydroxyl radical or a species with similar reactivity; and by superoxide dismutase and catalase, suggesting participation of superoxide and hydrogen peroxide, respectively. The decrease of S-amino acid release by sodium fluoride, sodium arsenate, 2,4-dinitrophenol, chloroquine, leupeptin, phenylmethylsulfonyl fluoride, EDTA and o-phenanthroline was variable, suggesting the presence in liver of several proteases to remove oxidatively-modified proteins.
authors.affiliation: Department of Food Science and Technology, University of California, Davis 95616.
authors.forename: R
authors.initials: R
authors.lastname: Zamora
authors.forename: F J
authors.initials: FJ
authors.lastname: Hidalgo
authors.forename: A L
authors.initials: AL
authors.lastname: Tappel
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001975:Bromotrichloromethane / Q000494:pharmacology*; D002614:Chelating Agents / Q000494:pharmacology; D003545:Cysteine / Q000378:metabolism; D016166:Free Radical Scavengers; D006868:Hydrolysis; D006878:Hydroxides / Q000378:metabolism; D017665:Hydroxyl Radical; D015227:Lipid Peroxidation; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008715:Methionine / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
chemical_list: D000975:Antioxidants; D002614:Chelating Agents; D016166:Free Radical Scavengers; D006878:Hydroxides; D011480:Protease Inhibitors; D017665:Hydroxyl Radical; D008715:Methionine; D001975:Bromotrichloromethane; D003545:Cysteine