Correlation among lipid peroxidation, brain energy metabolism and brain oedema in cerebral ischaemia

In order to study the involvement of lipid peroxidation in the generation of ischaemic cell damage, sequential measurements were made on the chemiluminescence, energy metabolism, water content and the volume of Na+ and K+ in the cerebral cortex using a rat model for severe cerebral ischaemia. It was found that the amount of chemiluminescence increased due to ischaemia and increased further following recirculation. In chemiluminescence spectral analysis, peaks were found at 480, 520-530, 570, 620-640, 680-700 nm. It is thought that these wavelengths reflect the release of energy due to the reduction of active oxygens to more stable states during the breakdown of lipid hydroperoxide. The recovery of ATP in the 5 min ischaemic brain after reflow with ATP stopped at approx. 60% of the pre-ischaemia level, whereas the water content of the cortex showed an increase after 5 min of recirculation, and a gradual recovery thereafter for 30 min. There was a strong correlation between the increase in cortical water content after recirculation and the amount of chemiluminescence. It is concluded that causes of the ischaemic cerebral oedema include not only decreased activation of ATP-dependent Na+, K+-ATPase, but also functional changes in ion channels due to an increase in free radicals following recirculation.