FIG. 1.

Mechanisms by which XOR-derived ROS might initiate either the inflammatory response or IR injury. XOR (XDH or XO) is upregulated by either inflammatory mediators or hypoxia and, in the presence of molecular oxygen, reduces the oxygen to ROS. ROS, in turn, upregulate cell adhesion molecules on endothelial cells and neutrophils, leading to adhesion and activation of these cells. The ensuing inflammatory response constitutes a normal antimicrobial defense, but it can also result in IR injury. Adapted from reference 46 with permission of the publisher.