Mitochondrial oxygen toxicity

Oxygen is an essential element necessary for eukaryotes to oxidize nutrients during cellular respiration and obtain most of their energy. Oxygen supplementation therapy is given to premature babies and adults in severe respiratory distress. However, since the 1870s researchers have been reporting the toxic effects of hyperoxia, that is, exposure to oxygen partial pressures higher than atmospheric (21%). Hyperoxia is one of many pathological conditions that increase the production of reactive oxygen species (ROS), resulting in intracellular oxidative stress. Mitochondria are both sources and targets of these ROS. In this chapter, we describe how hyperoxia-mediated oxidative stress impairs mitochondrial bioenergetics, induces oxidation of mitochondrial DNA, lipids, and proteins, and can ultimately lead to cell death and organ injury. Furthermore, we present evidence showing mitochondria-targeted antioxidants can protect against hyperoxic damage, suggesting a promising strategy against mitochondrial oxygen toxicity associated with oxygen therapies.