[Correlation with lipid peroxidation, brain energy metabolism and brain edema in cerebral ischemia]

Abstract

In order to unravel possible involvement of free radical reactions and lipid peroxidation in the ischemic cell damage, chemiluminescence, energy metabolism, water content and concentrations of Na+, K+ were measured with time, using highly ischemic whole brain models of rats. The amount of chemiluminescence value increased gradually with the ischemic load, and did markedly with recirculation of the blood flow. In the analysis of the intensity of chemiluminescence by wavelengths (the chemiluminescence spectroanalysis), the peaks were observed at 480, 520-530, 570, 620-640 and 680-700 nm. These wavelengths were taken to suggest the release of energy (luminescence) associated with the transition of singlet oxygen to the grounded state during the breakdown of the lipid hydroperoxide. When vitamin E was added on the brain homogenate in vitro, the luminescence was inhibited markedly for all the wavelengths mentioned above. With regard to the kinetics of energy metabolism, a short 5-minutes ischemic loading delayed recovery of adenine nucleotide after recirculation of the blood flow, and permitted ATP level to regain up to only about 60% of the pre-loading level. In case of the 5-minutes ischemic load, the cortical water content began to increase at 5 minutes after recirculation of the blood flow and showed sign of recovery in 30 minutes. The time-course increases in the cortical water content following recirculation of the blood flow well corresponded with the time-course changes in the amount of chemiluminescence value. And there seemed to be presented as the causes of ischemic cerebral edema not only the ATP-dependent lowering of activities of Na+, K+-ATPase, etc. by the free radicals, reinforced of the blood flow.