Figure 1.

Progressive loss of the pro-oxidant/antioxidant equilibrium with age and the synergic effect that ionizing radiation has on this process. Reactive oxygen species (ROS) production is greater in aging cells in comparison to their young counterparts; in addition, the antioxidant system is also compromised in these cells. This scenario leads to an increase in the oxidative stress. When adding ionizing radiation into this equation, the system becomes oversaturated, resulting in increased amounts of cell damage in aging cells. Red stars represent the ROS and the green triangles the antioxidant systems/enzymes.