Hyperoxia enhances lung and liver nuclear superoxide generation.
Porcine lung and liver nuclei generated superoxide (O-2) at a rate which increased with increasing oxygen concentration. NADH-dependent O-2 generation increased from 0 to 2.21 +/- 0.11 nmol/min per mg protein for lung nuclei and from 0.16 +/- 0.09 to 1.34 +/- 0.14 nmol/min per mg protein for liver nuclei, when oxygen concentration increased from 0 to 100%. NADPH-dependent O-2 generation increased similarly in liver nuclei (from 0.20 +/- 0.09 to 1.20 +/- 0.12 nmol/min per mg protein), while lung nuclei produced only 0.45 +/- 0.09 nmol/min per mg protein at 100% oxygen. NADH and NADPH had an additive effect on O-2 generation by liver nuclei, yielding 2.58 +/- 0.21 nmol/min per mg protein at 100% oxygen. Very little or no superoxide dismutase activity was present in washed nuclear preparations. The oxygen-dependence of nuclear O-2 generation shows that nuclear-derived partially reduced species of oxygen may affect nuclear function during hyperoxia or other metabolic situations where overproduction of oxygen radicals is problematic.
D000332:Aerobiosis; D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D003580:Cytochromes / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008168:Lung / Q000187:drug effects / Q000378:metabolism*; D008854:Microscopy, Electron; D010100:Oxygen / Q000633:toxicity*; D013481:Superoxides / Q000378:metabolism*; D013552:Swine
D003580:Cytochromes; D013481:Superoxides; D010100:Oxygen