The Generation of Superoxide Radicals by Cardiac Mitochondria and the Antioxidant Effect of the Water-Soluble Form of Ubiquinol-10

We have studied the effect of the water-soluble form of ubiquinol-10 (CoQ₁₀-H₂) on the processes of electron transport, oxidative phosphorylation, and the formation of reactive oxygen species in mitochondria isolated from the hearts of Wistar rats. It has been shown that preincubation of isolated mitochondria with different concentrations of ubiquinol-10 has only a minor effect on the rate of oxygen uptake and respiratory control. The interaction of ubiquinol-10 with superoxide radicals formed in complex III (bc₁ segment) of cardiac mitochondria has been studied using the EPR spin trapping and EPR oximetry method. Ubiquinol-10 has been found to act as an efficient antioxidant within the physiological range of the lipid concentrations, while the magnitude and kinetic characteristics of the antiradical effect depend on the drug concentration.