Use of iron chelators in preventing hydroxyl radical damage: adult respiratory distress syndrome as an experimental model for the pathophysiology and treatment of oxygen-radical-mediated tissue damage.

Tissue damage in many diseases is caused by hydroxyl radicals, generated during single electron reduction of oxygen. The first step is usually the formation of the superoxide radical. This radical is constantly formed in all living cells, and in particular during activation of phagocytes or during reoxygenation following ischaemia. Damage, however, only occurs in the presence of catalytic transition metals of which iron is the most important in human pathology. Oxygen-radical-mediated damage can be prevented by iron chelators, as has been demonstrated in numerous in vitro and in vivo experiments. A description is given as to how toxic oxygen products are formed in biological systems, and how organisms succeed in preventing autodestruction by scavenger molecules. The use of iron chelators to prevent oxygen radical damage is reviewed with emphasis on possible clinical applications. The adult respiratory distress syndrome is described in more detail as a model for oxygen-radical-mediated damage that can be successfully prevented with iron chelators.