title: The effect of phenobarbital pretreatment on the metabolism, covalent binding, and cytotoxicity of aflatoxin B1 in primary cultures of rat hepatocytes.
abstract: The effect of phenobarbital (PB) pretreatment on the metabolism, covalent binding, and cytotoxicity of [14C]aflatoxin B1 (AFB1) was studied in primary hepatocyte cultures. Hepatocytes from control and PB-pretreated rats were isolated from perfused liver biopsies and cultured in a chemically defined, hormone-supplemented medium. [14C]AFB1, dissolved in medium, was added to cultures at 20-22 h. The metabolism of AFB1 to water-soluble products and its binding to trichloroacetic acid-precipitable macromolecules were assessed 0.5 to 24 h later. At 6 h, PB pretreatment reduced total binding to macromolecules by 31% and reduced binding to RNA and DNA by 61% and 66%, respectively. In addition, PB protected cultures from the cytotoxic effects of AFB1, as evidenced by a significantly reduced (p less than 0.05) leakage of lactate dehydrogenase into the medium at 51 h. Elevated mixed-function oxidase and glutathione S-transferase activities, as well as higher levels of AFB1-glutathione conjugate were measured in cultures from rats pretreated with PB. The protective action of PB was concluded to be due to the induction of hepatic glutathione S-transferases responsible for the detoxification of AFB1.
mesh_terms: D016604:Aflatoxin B1; D000348:Aflatoxins / Q000378:metabolism* / Q000633:toxicity; D000818:Animals; D002250:Carbon Radioisotopes; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D004347:Drug Interactions; D005982:Glutathione Transferase / Q000378:metabolism; D008099:Liver / Q000187:drug effects* / Q000201:enzymology; D008297:Male; D006899:Mixed Function Oxygenases / Q000378:metabolism; D010634:Phenobarbital / Q000494:pharmacology*; D012313:RNA / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D000348:Aflatoxins; D002250:Carbon Radioisotopes; D012313:RNA; D004247:DNA; D016604:Aflatoxin B1; D006899:Mixed Function Oxygenases; D005982:Glutathione Transferase; D010634:Phenobarbital