title: Source of oxygen free radicals produced by rat hepatocytes during postanoxic reoxygenation.
abstract: The aim of this study was to determine the cellular source of oxygen free radicals generated by isolated hepatocytes during post-anoxic reoxygenation. Superoxide anions (O2.-) were detected by lucigenin chemiluminescence. Cell damage was assessed by LDH release. During anoxia, the chemiluminescence decreased to background levels while LDH release increased 8-fold. During reoxygenation, O2.- formation increased 15-fold within 15 min then declined towards control levels. LDH release increased from 161 to 285 mU/min in the first 30 min of reoxygenation, then declined toward the control rate. Allopurinol, an inhibitor of the xanthine-xanthine oxidase system, did not inhibit O2.- formation nor LDH release. Antimycin, a mitochondrial complex III inhibitor that does not block O2.- formation, increased both O2.- generation and LDH release 82 and 133% respectively. Diphenyleneiodonium (DPI), a mitochondrial and microsomal NADPH oxidase inhibitor, reduced O2.- and LDH release 60-70%. SOD, which catalyzes the dismutation of O2.- to H2O2, was without effect on O2.- and LDH release, but TEMPO, a stable nitroxide which mimics SOD and easily penetrates the cell membrane, decreased O2.-86% without affecting LDH. These results suggest that mitochondria or microsomes are the principal sites of O2.- production during reoxygenation of isolated hepatocytes, whereas the cytosolic xanthine/xanthine oxidase system is apparently not involved.
authors.affiliation: Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, PA 15261, USA.
authors.forename: P
authors.initials: P
authors.lastname: Caraceni
authors.forename: H S
authors.initials: HS
authors.lastname: Ryu
authors.forename: D H
authors.initials: DH
authors.lastname: van Thiel
authors.forename: A B
authors.initials: AB
authors.lastname: Borle
mesh_terms: D000493:Allopurinol / Q000494:pharmacology; D000818:Animals; D000968:Antimycin A / Q000494:pharmacology*; D002478:Cells, Cultured; D003497:Cyclic N-Oxides / Q000494:pharmacology; D000860:Hypoxia / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D008099:Liver / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism; D008930:Mitochondria, Liver / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013482:Superoxide Dismutase / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism*; D014969:Xanthine Oxidase / Q000037:antagonists & inhibitors
chemical_list: D003497:Cyclic N-Oxides; D013481:Superoxides; D000493:Allopurinol; D000968:Antimycin A; D007770:L-Lactate Dehydrogenase; D013482:Superoxide Dismutase; D014969:Xanthine Oxidase; D010100:Oxygen; C003959:TEMPO