title: Free radical-mediated pre-hemolytic injury in human red blood cells subjected to lead acetate as evaluated by chemiluminescence.
abstract: The mechanisms by which Pb(2+) induces hemolysis are not completely understood. For this reason, the involvement of oxidative stress in the mechanism of Pb(2+)-induced pre-hemolytic lesion was investigated by exposing RBC to Pb(2+) in vitro and then separating the intact non-hemolysed RBC. Oxidative stress was investigated on human RBCs by tert-butyl hydroperoxide-initiated chemiluminescence method (CL). Our results revealed that lead-induced time and concentration-dependent hemolysis and CL time curves showed a very narrow correlation each other. GSH oxidation to GSSG and the stress index also increased significantly. Treatment of lead-exposed RBC with desferrioxamine, an iron-chelating agent or the chain-breaking antioxidant, Trolox, quenched light emission and inhibited hemolysis dramatically. Mannitol and sodium formate, (*)OH scavengers, on the contrary, did not inhibit CL or hemolysis, significantly. These data indicate that lead-induced lipid peroxide formation is mediated by a metal-driven Fenton reaction but do not support the direct involvement of hydroxyl radicals in this process. By contrast, our results revealed a decrease in light emission and decreased hemolysis in the presence of histidine, a singlet oxygen scavenger. Our results suggest that membrane damage and hemolysis of RBC are mediated by Pb(2+) through free radical reactions and that singlet oxygen plays a significant role in this process.
authors.affiliation: Pathophysiology Laboratory of Free Radicals, Department of Pathological Sciences, Universidade Estadual de Londrina, 86051-990 Londrina, Brazil.
authors.forename: M F
authors.initials: MF
authors.lastname: Casado
authors.forename: A L
authors.initials: AL
authors.lastname: Cecchini
authors.forename: A N C
authors.initials: AN
authors.lastname: Simão
authors.forename: R D
authors.initials: RD
authors.lastname: Oliveira
authors.forename: R
authors.initials: R
authors.lastname: Cecchini
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D002839:Chromans / Q000494:pharmacology; D003676:Deferoxamine / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000187:drug effects*; D004912:Erythrocytes / Q000187:drug effects* / Q000378:metabolism; D005561:Formates / Q000494:pharmacology; D005609:Free Radicals / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism; D006461:Hemolysis / Q000187:drug effects*; D006490:Hemostatics / Q000494:pharmacology; D006639:Histidine / Q000494:pharmacology; D006801:Humans; D008163:Luminescent Measurements / Q000379:methods; D008353:Mannitol / Q000494:pharmacology; D009942:Organometallic Compounds / Q000633:toxicity*; D018384:Oxidative Stress / Q000502:physiology; D017262:Siderophores / Q000494:pharmacology; D020122:tert-Butylhydroperoxide / Q000378:metabolism
chemical_list: D000975:Antioxidants; D002839:Chromans; D005561:Formates; D005609:Free Radicals; D006454:Hemoglobins; D006490:Hemostatics; D009942:Organometallic Compounds; D017262:Siderophores; C030544:formic acid; D008353:Mannitol; D006639:Histidine; D020122:tert-Butylhydroperoxide; D005978:Glutathione; D003676:Deferoxamine; C008261:lead acetate; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid