Effects of reactive oxygen species on intracellular calcium in bovine tracheal epithelium: modulation by nitric oxide.
We studied the effects of reactive oxygen species (ROS) on intracellular Ca2+ concentration ([Ca2+]i) and their possible modulation by nitric oxide (NO) in fura-2-loaded cultured bovine tracheal epithelium. Hypoxanthine (HX) and xanthine oxidase (XO), which generate superoxide anion (O2-) and hydrogen peroxide (H2O2), dose dependently increased [Ca2+]i. The increase in [Ca2+]i was reduced in the presence of superoxide dismutase (SOD, 200 U/mL) and catalase (200 U/mL) by 29% and 43%, respectively. The iron chelator o-phenanthroline and the hydroxyl radical (.OH) scavenger dimethylthiourea (DMTU) more potently inhibited the response of [Ca2+]i. H2O2-derived .OH generated by the Fenton reaction caused a marked [Ca2+]i elevation, but exogenous H2O2 did not. Sodium nitroprusside (100 microM), an NO donor, potentiated HX-XO-induced [Ca2+]i rise by 50%, an effect that was abolished in the presence of SOD or DMTU. These results suggest that .OH formed by interaction of O2- and H2O2 in the presence of iron may play a major role in the HX-XO-induced disruption of airway epithelial Ca2+ homeostasis, and that NO potentiates ROS-induced [Ca2+]i response, presumably by reacting with O2- and producing .OH.
Kanoh
S
S
Third Department of Medicine, National Defense Medical College, Saitama, Japan.
Kondo
M
M
Tamaoki
J
J
Kobayashi
H
H
Motoyoshi
K
K
Nagai
A
A
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002374:Catalase / Q000494:pharmacology; D002417:Cattle; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D019271:Hypoxanthine / Q000494:pharmacology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology*; D009599:Nitroprusside / Q000494:pharmacology; D010618:Phenanthrolines / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000502:physiology; D013482:Superoxide Dismutase / Q000494:pharmacology; D013481:Superoxides / Q000494:pharmacology*; D013890:Thiourea / Q000031:analogs & derivatives* / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects / Q000378:metabolism*; D014969:Xanthine Oxidase / Q000494:pharmacology
D010618:Phenanthrolines; D017382:Reactive Oxygen Species; D013481:Superoxides; D009599:Nitroprusside; D019271:Hypoxanthine; D009569:Nitric Oxide; C038983:1,3-dimethylthiourea; D006861:Hydrogen Peroxide; D007770:L-Lactate Dehydrogenase; D002374:Catalase; D013482:Superoxide Dismutase; D014969:Xanthine Oxidase; D013890:Thiourea; D002118:Calcium; C025205:1,10-phenanthroline