The generation of superoxide radicals by complex III in heart mitochondria and the antioxidant effect of dinitrosyl iron complexes at different partial pressures of oxygen

Resumo

EPR spin trapping and EPR oximetry were used to study the superoxide radical generation in heart mitochondria from Wistar rats at various oxygen concentrations. Lithium phthalocyanine and TEMPONE-¹⁵N-D₁₆ were chosen to determine the oxygen content in a gas-permeable capillary containing mitochondria. TIRON was used as a spin trap. Several oxygen concentrations in the incubation mixture were tested; heart mitochondria were found to generate superoxide in complex III at various partial pressures of oxygen, including deep hypoxia (<5% O₂). Dinitrosyl iron complexes with glutathione (the drug Oxacom) exerted an antioxidant effect regardless of the partial pressure of oxygen; the magnitude and kinetic characteristics of the effect depended on the drug concentration.