Mitochondrial NADH-quinone Oxidoreductase (NQOm) Produces Reactive Oxygen Species in the Chemical Injury of Rat Liver Mitochondria

The generation of reactive oxygen species in the mitochondria was investigated using electron microscopic cytochemistry and energy-filtering transmission electron microscopy in reference to the toxic mediator of paraquat poisoning. When isolated intact mitochondria from rat livers were reacted with paraquat in the presence of NADH, mitochondrial NADH-quinone oxidoreductase generated superoxide anions to cause the destruction of mitochondria which resulted in cell death. Cerium chloride captured hydrogen peroxide and formed cerium perhydroxide precipitates on the outer surface of the mitochondrial outer membrane. This localization was also clearly identified with electron spectroscopic imaging based on electron energy loss spectral analysis.