The Role of Exercise-Mediated Mitochondrial ROS Production in the Regulation of Oxidative Phosphorylation

The transport of long chain fatty acids (LCFA) and ADP into the mitochondria are two major control points of oxidative phosphorylation that can be upregulated during exercise in order to maintain cellular ATP demand. The rate-limiting steps of LCFA and ADP transport are thought to be sensitive to redox modification, suggesting the importance of exercise-mediated mitochondrial ROS production. Therefore, we used MCAT mice, which have human catalase targeted to the mitochondria, to determine if decreasing mitochondrial ROS emission affects oxidative phosphorylation. Attenuating mitochondrial ROS significantly reduced exercise capacity in the absence of alterations in mitochondrial content. While an acute bout of exercise decreased ADP sensitivity by ~30% in WT mice, MCAT mice retained ADP sensitivity. In contrast, while exercise decreased MCoA-mediated inhibition of lipid-supported respiration, the responses within WT and MCAT mice were similar. Altogether, these findings demonstrate that exercise-mediated mitochondrial ROS emission regulates ADP sensitivity, but not lipid-supported respiration.