Modification of cardiac action potential by photosensitizer-generated reactive oxygen

Evidence implicating reactive oxygen species (ROS) in reperfusion-induced arrhythmias is accumulating rapidly [1,2]. However, surprisingly little is known about the effects of ROS on cardiac electrophysiology. Such knowledge would improve our understanding of reperfusion-induced arrhythmias. Photosensitizers and light are known to produce a variety of ROS. They might, therefore, be useful for investigating oxygen-mediated cell injury. To our knowledge, such an approach has not been used to investigate ROS-induced alterations in the electrophysiological properties of cardiac muscle. The purpose of this paper is to demonstrate (1) the feasibility of using photosensitizers for such an investigation, and (2) some advantages photosensitizers offer when combined with single cell and patch pipette methodologies. A comparison of the electrophysiological alterations produced by photosensitizer-generated ROS to the reported effects of xanthine-xanthine oxidase or organic hydroperoxides suggests that the electrophysiological alterations produced by superoxide initiated reactions and/or lipid peroxidation are similar to those produced by photosensitizers and light.