Role of ATP and glycogen reserves in both paracetamol sulfation and glucuronidation by cultured precision-cut rat liver slices.
Precision-cut rat liver slices (PCLS) were used to investigate the formation of paracetamol conjugates. The time course of biochemical markers such as ATP and GSH content, glycogen levels and protein synthesis rates was recorded over a period of time of 26 h and taken as index of slices viability. Low values of ATP (3.6 nmol/mg prot), GSH (7.1 nmol/mg prot) and protein synthesis rates (94.1 pmol leu/mg prot x min(-1)) were initially observed. Thereafter, they gradually recovered up to 6 h but decreased values were seen after 20 h. Glycogen, however, dropped rapidly during the first 6 h, being no longer detected after 20 h of incubation. The reincubation of PCLS in a fresh medium for 6 h allowed a strong recovery of GSH, ATP and protein synthesis rates, but no gluconeogenesis was observed. Meanwhile, paracetamol sulfate formation was fairly constant (about 3 microg/mg protein) while glucuronide gradually disappeared. The amount of both UGT1A1 and ST1A1 did not correlate with their respective enzymatic activities. We suggest that loss of glycogen impair glucuronide conjugation by decreasing the availability of UDPGA, and that low values of ATP are largely enough to support sulfotransferase activity.
Evdokimova
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Unité de Pharmacocinétique, Métabolisme, Nutrition et Toxicologie, Département de Sciences Pharmaceutiques, Université Catholique de Louvain, Brussels, Belgium.
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Buc Calderon
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D000082:Acetaminophen / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000032:analysis / Q000378:metabolism*; D018712:Analgesics, Non-Narcotic / Q000378:metabolism*; D000818:Animals; D015239:Arylsulfotransferase / Q000032:analysis / Q000378:metabolism*; D020719:Glucuronides / Q000378:metabolism; D014453:Glucuronosyltransferase / Q000032:analysis / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism; D006003:Glycogen / Q000032:analysis / Q000378:metabolism*; D015151:Immunoblotting; D066298:In Vitro Techniques; D008099:Liver / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D014176:Protein Biosynthesis; D051381:Rats; D017208:Rats, Wistar; D014535:Uridine Diphosphate Glucuronic Acid / Q000378:metabolism; D000099148:UGT1A1 Enzyme
D000082:Acetaminophen; D000255:Adenosine Triphosphate; D018712:Analgesics, Non-Narcotic; D015239:Arylsulfotransferase; D020719:Glucuronides; D014453:Glucuronosyltransferase; D005978:Glutathione; D006003:Glycogen; D014535:Uridine Diphosphate Glucuronic Acid; D000099148:UGT1A1 Enzyme; C499946:Ugt1a1 protein, rat