title: In vivo dual effects of vitamin C on paraquat-induced lung damage: dependence on released metals from the damaged tissue.
abstract: Vitamin C, a potent antioxidant, can act as a pro-oxidant in the presence of free transition metal ions by accelerating the Fenton reaction. An in vivo pro-oxidant role of vitamin C has been suggested, but direct evidence for it is scant. Here, we report the dual role of vitamin C on paraquat-induced lung injury, which appears to depend on the metal ions released from damaged cells. Vitamin C (10 mg/kg) given at the time when the extensive tissue damage was in progress aggravated the oxidative damage, while it protected against the damage when given before the initiation of the damage. The extent of oxidative tissue damage was monitored by measuring the expiratory ethane, one of the hydrocarbons produced during lipid peroxidation. Deferoxamine, given intraperitoneally as a bolus dose of 50 mg/kg, completely blocked the aggravation of oxidative damage by vitamin C. Moreover, deferoxamine unmasked the antioxidant effect of vitamin C. The results show that vitamin C can either aggravate or alleviate the oxidative tissue damage depending on the presence of metal ions released from damaged cells.
authors.affiliation: Department of Physiology, University of Ulsan College of Medicine, Seoul, South Korea.
authors.forename: S A
authors.initials: SA
authors.lastname: Kang
authors.forename: Y J
authors.initials: YJ
authors.lastname: Jang
authors.forename: H
authors.initials: H
authors.lastname: Park
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use; D001944:Breath Tests; D003676:Deferoxamine / Q000494:pharmacology; D004980:Ethane / Q000032:analysis; D015227:Lipid Peroxidation; D008168:Lung / Q000378:metabolism / Q000473:pathology; D008171:Lung Diseases / Q000139:chemically induced* / Q000378:metabolism / Q000517:prevention & control; D008297:Male; D008670:Metals / Q000378:metabolism*; D010084:Oxidation-Reduction; D010269:Paraquat / Q000633:toxicity*; D011506:Proteins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D008670:Metals; D011506:Proteins; D003676:Deferoxamine; D004980:Ethane; D010269:Paraquat; D001205:Ascorbic Acid