The mitochondrion is a major source of reactive oxygen species (ROS). Superoxide (O 2•−)
is generated under specific bioenergetic conditions at several sites within the electron-
transport system; most is converted to H 2 O 2 inside and outside the mitochondrial matrix by
superoxide dismutases. H 2 O 2 is a major chemical messenger that, in low amounts and
with its products, physiologically modulates cell function. The redox state and ROS
scavengers largely control the emission (generation scavenging) of O 2•−. Cell ischemia …

Reactive oxygen species (ROS) play an important role in cardiovascular diseases, and one
important source for ROS are mitochondria. Emission of ROS from mitochondria is the net
result of ROS production at the electron transport chain (ETC) and their elimination by
antioxidative enzymes. Both of these processes are highly dependent on the mitochondrial
redox state, which is dynamically altered under different physiological and pathological
conditions. The concept of “redox-optimized ROS balance” integrates these aspects and …