[An experimental study of acute brain ischemia followed by reperfusion in rhesus monkeys]

Acute brain ischemia was accomplished in 18 rhesus monkeys through bilateral occlusion of the vertebral and carotid arteries. The temporary blood volumes (TBV) of the corresponding areas of the ischemic brains were compared with those of the normal controls. At the time of brain ischemia the TBV in basilar ganglion and internal capsule decreased significantly (7.28%) and that in the temporal cortex decreased moderately (22.76%) while the TBV in the brain stem did not show significant changes. The amplitude of EEG was suppressed or became isoelectric immediately after 15 minutes of ischemia. The EEG slightly restored following a reperfusion of 120 minutes, but it became irreversible if ischemia lasted more than 30 minutes. The sodium and water content increased as ischemic was prolonged. This was more significant after recirculation. Ultrastructural findings showed that mitochondria, endoplasmic reticulum and astrocytic processes became swollen after 15 minutes of ischemia. When ischemia lasted more than 30 minutes, mitochondria became swollen more significantly with ruptured cresta. There were marked margination of nuclear clumping chromatins. According to these changes the neuron underwent irreversible injury. As ischemia lasted more than 60 minutes these changes became more apparent, i,e, the mitochondria contained amorphous matrix densities. The nuclear chromatin showed aggregated clumping. The cellular membranes were damaged and the blood vessels contained microemboli. After reperfusion it became much more serious.