Mitochondrial pathways for ROS formation and myocardial injury: The relevance of p66Shc and monoamine oxidase

Although mitochondria are considered the most relevant site for the formation of reactive oxygen species (ROS) in cardiac myocytes, a major and unsolved issue is where ROS are generated in mitochondria. Respiratory chain is generally indicated as a main site for ROS formation. However, other mitochondrial components are likely to contribute to ROS generation. Recent reports highlight the relevance of monoamine oxidases (MAO) and p66^Shc. The importance of these systems in the irreversibility of ischemic heart injury will be discussed along with the cardioprotective effects elicited by both MAO inhibition and p66^Shc knockout. Finally, recent evidence will be reviewed that highlight the relevance of mitochondrial ROS formation also in myocardial failure and atherosclerosis.