title: Glutathione modulation changes the penetration of N-[3H]methyl-N-nitro-N-nitrosoguanidine into gastric mucosa of rats.
abstract: Glutathione plays a role in gastric mucosal protection and the glutathione level is elevated in some forms of gastritis. We studied the relevance of glutathione for the penetration of N-methyl-N-nitro-N-nitrosoguanidine in the glandular mucosa of the stomach. Male Wistar rats were treated with glutathione (0.5 mmol/kg intravenously), N-acetylcysteine (0.5 mmol/kg intravenously), or L-buthionine-[S,R,]-sulfoximine (BSO, 2 mmol/kg intraperitoneally), before the gastric mucosa was exposed to N-[3H]methyl-N-nitro-N-nitrosoguanidine for 10 min. Penetration of the carcinogen was evaluated by light microscopic identification of cells labeled with bromodeoxyuridine and N-[3H]methyl-N-nitro-N-nitrosoguanidine (double-labeled cells). Thiol substances were quantified by reversed-phase ion-pair liquid chromatography and fluorescence detection. The percentage double-labeled cells was higher in antrum mucosa (11.7 +/- 3.1%) than in corpus mucosa (1.1 +/- 0.2%) (P < 0.05). Total glutathione level was 1853 +/- 101 nmol/g in antrum and 1560 +/- 76 nmol/g in corpus mucosa. BSO administration reduced the amount of glutathione in antrum to 495 +/- 14 nmol/g (P < 0.05) and reduced the percentage double-labeled cells in antrum mucosa to 6.1 +/- 1.3% (P < 0.05). A positive correlation was found between the percentage of double-labeled cells in the antrum mucosa and the total amount of glutathione (r = 0.451, P = 0.002), and the amount of reduced glutathione (r = 0.449, P = 0.002). Glutathione modulation effects the penetration of N-[3H]methyl-N-nitro-N-nitrosoguanidine in the antrum but not in the corpus mucosa. Thiols do not explain the different penetration of carcinogen in antrum and corpus mucosa.
authors.affiliation: Department of Surgery, University of Bergen, Haukeland University Hospital, Norway.
authors.forename: K K
authors.initials: KK
authors.lastname: Ovrebø
authors.forename: A
authors.initials: A
authors.lastname: Svardal
authors.forename: S
authors.initials: S
authors.lastname: Kvinnsland
authors.forename: K
authors.initials: K
authors.lastname: Grong
authors.forename: K
authors.initials: K
authors.lastname: Svanes
authors.forename: H
authors.initials: H
authors.lastname: Sørbye
mesh_terms: D000818:Animals; D002273:Carcinogens / Q000493:pharmacokinetics* / Q000633:toxicity; D003545:Cysteine / Q000378:metabolism; D004151:Dipeptides / Q000378:metabolism; D005753:Gastric Mucosa / Q000187:drug effects* / Q000378:metabolism; D005978:Glutathione / Q000494:pharmacology / Q000502:physiology*; D006710:Homocysteine / Q000378:metabolism; D008297:Male; D008769:Methylnitronitrosoguanidine / Q000493:pharmacokinetics* / Q000633:toxicity; D051381:Rats; D017208:Rats, Wistar
chemical_list: D002273:Carcinogens; D004151:Dipeptides; D006710:Homocysteine; D008769:Methylnitronitrosoguanidine; C028505:cysteinylglycine; D005978:Glutathione; D003545:Cysteine