Early effects on restoration of evoked field potentials in the hippocampal CA(1) region after reversible hypoxia/hypoglycemia by the radical scavenger N-tert.-butyl-alpha-phenylnitron.

In transverse hippocampus slices a short period of hypoxia/hypoglycemia induced by perfusion with an O(2)/glucose-free medium caused early loss and incomplete restoration of evoked field potentials in the CA(1) region. In the present study a search was made for whether the formation of free oxoradicals immediately after starting the hypoxic phase could be part of the breakdown and incomplete restoration of the excitatory potentials (EPs). It was shown that preincubation and postischemic incubation with the radical scavenger PBN did not prevent the potential breakdown but significantly enhances potential restoration, even when PBN was added to the perfusion medium 40 min after hypoxia. Thus, free oxoradicals may damage membrane constituents such as receptors or channel proteins at a very early phase, before neuronal death is pronounced. The results also show that treatment with radical scavengers has a beneficial effect on early hypoxic damage.