title: Promotion of trans-platinum in vivo effects on renal heme and hemoprotein metabolism by D,L-buthionine-S,R-sulfoximine. Possible role of glutathione.
abstract: We have examined the toxicity of trans-platinum (trans-diamminedichloroplatinum II) to heme and hemoprotein metabolism in the kidney of glutathione (GSH)-depleted rats and compared it with that produced by cis-platinum. Unlike cis-platinum treatment (7.0 mg/kg, i.v.) which caused after 7 days significant increases in cytochromes P450 and b5, and a marked decrease in porphyrin content of the kidney, trans-platinum alone (7 mg/kg, i.v.) did not elicit notable changes in these variables when measured 1 or 7 days after treatment. Also, cis-platinum treatment significantly altered the heme degradation pathway by increasing the activity of heme oxygenase and decreasing that of biliverdin reductase; trans-platinum treatment did not elicit a response in these activities. However, when rats were given the inhibitor of GSH synthesis, D,L-buthionine-S,R-sulfoximine (BSO), the subsequent administration (2 hr later) of trans-platinum produced, in 1 day, the spectrum of responses that were mediated by cis-platinum after 7 days. In the kidneys of rats treated with BSO plus trans-platinum the concentration of platinum measured only about 50% of that detected in the kidneys of rats treated with trans-platinum alone. In the liver, trans-platinum by itself or in combination with BSO was ineffective in altering the measured variables of heme metabolism. The possibility that similarity between cis-platinum and trans-platinum plus BSO may extend to systems other than heme metabolism, e.g. GSH synthesis and degradation, was examined. cis-Platinum caused significant inhibition of both renal gamma-glutamyl synthetase and gamma-glutamyl transpeptidase after 7 days, but not after 1 day. Twenty-four hours after treatment, BSO + trans-platinum caused inhibition of gamma-glutamylcysteine synthetase activity, whereas this activity in animals treated with BSO alone had returned to control values. At this time point, neither oxidized glutathione (GSSG)-reductase nor gamma-glutamyl transpeptidase activity was affected by trans-platinum + BSO treatment. The findings suggest that GSH constitutes an important defense mechanism against trans-platinum alteration of heme metabolism and may play a role in cellular accumulation of the drug in an inactive complex. It is proposed that BSO treatment, despite resulting in a diminished intracellular concentration of trans-platinum, allows reaction of the metal complex with target molecules by virtue of its ability to deplete GSH.
authors.affiliation: Department of Urology, University of Rochester School of Medicine, NY 14642.
authors.forename: R D
authors.initials: RD
authors.lastname: Mayer
authors.forename: M D
authors.initials: MD
authors.lastname: Maines
mesh_terms: D000818:Animals; D019328:Buthionine Sulfoximine; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004357:Drug Synergism; D005978:Glutathione / Q000172:deficiency / Q000378:metabolism*; D006419:Heme Oxygenase (Decyclizing) / Q000378:metabolism; D007668:Kidney / Q000032:analysis / Q000187:drug effects* / Q000201:enzymology; D008297:Male; D008717:Methionine Sulfoximine / Q000031:analogs & derivatives* / Q000494:pharmacology; D009944:Organoplatinum Compounds / Q000494:pharmacology*; D010984:Platinum / Q000032:analysis; D011166:Porphyrins / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013237:Stereoisomerism; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D009944:Organoplatinum Compounds; D011166:Porphyrins; D008717:Methionine Sulfoximine; D010984:Platinum; D019328:Buthionine Sulfoximine; D003577:Cytochrome P-450 Enzyme System; D006419:Heme Oxygenase (Decyclizing); D005978:Glutathione