Abstract

Increased Levels of Reactive Oxygen Species in Brain Slices after Transient Hypoxia Induced By a Reduced Oxygen Supply

Author(s): Toru Sasaki, Takuji Awaji, Kazuyoshi Shimada, Haruyo Sasaki

Abstract

Background: Reactive oxygen species (ROS) have been suggested to be involved in cellular damage caused by ischemia-reperfusion, anoxia-reperfusion, and hypoxia-reperfusion. We previously demonstrated that the generation of ROS was enhanced following hypoxia caused by an increased oxygen demand, and this was related to a shift in the tissue redox balance toward reduction. The aim of the present study was to elucidate the relationship among changes in ROS generation, tissue pO2 levels, and redox balance changes in brain slices following hypoxia caused by a decreased oxygen supply.

Methods We measured ROS-dependent chemiluminescence in cerebral cortex slices using a photonic imaging method as well as tissue pO2 levels and the redox balance using micro sensors during reoxygenation after hypoxia caused by the deprivation of an adequate oxygen supply.

Results ROS-dependent chemiluminescent intensity was transiently enhanced during reoxygenation after the hypoxic treatment. Tissue pO2 levels decreased and the tissue redox balance shifted towards reduction with the hypoxic treatment, followed by restoration to the steady-state condition. Increased ROS generation following hypoxia was related to a transient decrease in tissue pO2 levels and a shift in the tissue redox balance towards reduction.

Conclusions The present results demonstrated that ROS generation increased following hypoxia caused by a decreased oxygen supply. In addition, a transient redox shift to “hyper-reduction” with pO2 changes may be involved in ROS generation in tissue.