Neurologic and cytologic outcome following repeated ischemia. Effect of pentobarbital

We examined clinical recovery from repeated brain ischemic insults that have been reported to affect cytologic outcome. Brain ischemia was induced in the rat by four-vessel occlusion. A 30-min ischemia was given as a single insult or induced in animals made ischemic 24 h earlier by a 10-min insult but exempt both of brain hypoperfusion and neurologic deficit in spite of a partial necrosis of the CA1 sector of hippocampus. Repeated ischemia was associated with a significantly poorer clinical outcome as indicated by an increase in percentage of rats that exhibited postischemic seizure activity combined with the percentage of unconvulsive rats exhibiting neurologic deficits after 72 h of reperfusion (81% vs. 50% after a single 30-min ischemia). Examination of hippocampal damage showed that neurons surviving the first ischemia did not acquire resistance to the second ischemia. Pentobarbital given from start of overt seizures (30 to 60 mg/kg, IP, thrice daily) was able to stop convulsions and to antagonize processes involved in ischemia-induced neuronal death of CA1 hippocampus.