Recovery of Monkey Brain after Prolonged Ischemia. I. Electrophysiology and Brain Electrolytes

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Abstract
Adult normothermic monkeys were submitted to 1 h of total cerebral ischemia, followed by blood recirculation for 1.5–24 h. During ischemia EEG and evoked potentials were suppressed within 12 s and 3 min, respectively. Upon recirculation, high-voltage EEG bursts began to reappear after 82–125 min, followed by gradual return of continuous background activity and near normalization of EEG frequency pattern within 24 h. Somatically evoked potentials, in contrast, exhibited only partial recovery, and consciousness did not return during the observation period. At the end of the experiments, tissue contents of sodium, potassium, calcium, and magnesium were measured in the gray and white matter of parietal lobe by atomic absorption spectros-copy. Gray matter sodium content gradually increased by ∼50% from 41.0 to 59.8 μmol/g wet wt during 24 h of recirculation. The other electrolytes including calcium did not change during the observation period. Postisch-emic recovery reported in this and the accompanying article is attributed to careful control of postischemic general physiological state and prevention or treatment of postischemic complicating side effects such as postischemic brain edema, hypotension, acidosis, pulmonary distress, and anuria. No specific drug treatment such as application of calcium antagonists or metabolic inhibitors was necessary to achieve this effect.