Cytochemical Localization of H2O2 in Biological Tissues

Free radicals and free radical-derived oxidants play important roles in biological systems and have been implicated in the pathology of many diseases. The major problem in determining the role of reactive oxygen species (ROS) has been that these short-lived species are difficult to measure in vivo (1 ). ROS in cells and tissues have been demonstrated by a number of methods. Effects of free radical scavengers such as superoxide dismutase (SOD), catalase, glutathione peroxidase, and antioxidants such as vitamin E have been detected indirectly (2 ,3 ). Many of the approaches used in free radical studies provide an aggregate assessment of oxidative stress but do not show specific information about the in situ subcellular sites of distribution of specific free radicals such as can be revealed by cytochemical approaches.