Adaptation of adult brain tissue to anoxia and hypoxia in vitro.

The rat hippocampal slice preparation was used in the present study to demonstrate the ability of adult brain tissue to adapt to anoxic and hypoxic conditions. Adaptation was induced by pre-exposure of hippocampal slices to a short (5 min) anoxic episode. The evoked electrical activity of pre-exposed slices recovered from a subsequent, longer anoxic insult, while that of controls (without pre-exposure), receiving the same insult, did not. The adaptation process is time-dependent; an interval of 0.5 h between the pre-exposure and the subsequent anoxic insult allowed slices to resist anoxic periods of 13 +/- 2 min while after an interval of 2 h an anoxic period of 16 +/- 2 min could be tolerated. Evoked electrical activity persisted in adapted slices during exposure to hypoxia while their non-adapted controls exhibited synaptic silence under hypoxic conditions.