Mitochondria have been pivotal in the development of some of the most important ideas in modern biology. Since the discovery that the organelle has its own DNA and specific mutations were found in association with neuromuscular and cardiovascular diseases and with aging, an extraordi-nary number of publications have followed, and the term mitochondrial medicine was coined. Furthermore, our understanding of the multiple roles that mitochondria play in cardiac cell homeostasis opened the door for intensive experimentation to understand the pathogenesis and to find new treatments for cardiovascular diseases. Besides its role in adenosine triphosphate generation, mitochondria regu-late a complex network of cellular interactions, involving 1 generation and detoxification of reactive oxygen species, including superoxide anion, hy-drogen peroxide, and hydroxyl radical 2 maintenance of the antioxidant glutathione in a reduced state and adequate level of mitochondrial matrix superoxide dismutas