Cerebral energy metabolism and computerized EEG. Analysis following transient ischemia in the rat

1. Cerebral energy metabolism and electroencephalogram (EEG) power spectra were evaluated before, during and after 1 minute of global compression ischemia induced in N2O anesthetized rats. 2. Before ischemia, the EEG of rats was characterized by theta and delta frequencies. During ischemia, the EEG flattened after 14 +/- 1 sec and the electrical activity reappeared 55 +/- 4 s after recirculation and was characterized by high amplitude slow waves. After ischemia, the total power showed a rapid rebound mainly due to a 10 fold increase of delta band. 10 minutes after recirculation, the EEG was normal. 3. The ischemia induced a decrease of phosphocreatine, ATP and glucose, and an increase of ADP, AMP and lactate, while pyruvate remained normal. During recirculation phosphocreatine, ATP, glucose and energy charge potential showed a rapid recovery. AMP normalized after 10 minutes, while ADP was slightly higher for up to 30 minutes. Lactate returned to normal levels after 30 minutes and pyruvate showed a high peak at 3 minutes and returned to normal values after 30 minutes. 4. The results suggest that there is not a correlation between EEG and the metabolic pattern of recovery after a short complete ischemia.