title: Depletion of tissue glutathione with diethyl maleate enhances hyperbaric oxygen toxicity.
abstract: Rats exposed to hyperbaric hyperoxia experience severe central nervous system and lung toxicity. Exogenous glutathione administration has been shown to protect rats from the effects of hyperbaric hyperoxia. To explore the hypothesis that decreases in tissue glutathione (GSH) could increase the susceptibility of rats to hyperbaric hyperoxia, we administered diethyl maleate (DEM) (a compound that conjugates with GSH and rapidly lowers tissue levels) and measured tissue GSH levels. DEM administration decreased plasma GSH by 86%, liver GSH by 82%, and brain GSH by 45% between 2 and 4 h after injection with values returning to normal by 24 h. We then treated rats with DEM or saline and began exposure at 2 h after treatment to 100% oxygen at 4 ATA. Time-to-convulsion and time-to-death were recorded. Rats that received DEM 2 h before exposure seized earlier and died earlier than controls. Intraperitoneal administration of GSH to DEM-treated rats abolished the enhanced toxicity occurring during a hyperbaric hyperoxic exposure. DEM appears to increase the toxicity of rats exposed to hyperbaric hyperoxia by lowering tissue GSH levels, and replenishment of lung and brain GSH by exogenous administration reverses these effects.
authors.affiliation: Lung Metabolic Unit, University of Texas Health Science Center, Wilford Hall Medical Center.
authors.forename: C A
authors.initials: CA
authors.lastname: Weber
authors.forename: C A
authors.initials: CA
authors.lastname: Duncan
authors.forename: M J
authors.initials: MJ
authors.lastname: Lyons
authors.forename: S G
authors.initials: SG
authors.lastname: Jenkinson
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D005978:Glutathione / Q000031:analogs & derivatives / Q000378:metabolism*; D019803:Glutathione Disulfide; D005979:Glutathione Peroxidase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D008168:Lung / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D008297:Male; D008298:Maleates / Q000494:pharmacology*; D010100:Oxygen / Q000633:toxicity*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D008298:Maleates; D005979:Glutathione Peroxidase; D005980:Glutathione Reductase; D005982:Glutathione Transferase; C014476:diethyl maleate; D005978:Glutathione; D010100:Oxygen; D019803:Glutathione Disulfide