<p>Ischemia was induced for 30 minutes, 2 hours after the <i>in vitro</i> placement of the isolated brain. NC were perfused for 1 h immediately either after the reopening of the vessel or 1 our later (protocol 2). The perfusion was followed by a wash-out period with a solution without NCs. At 5 hours <i>in vitro</i> the brains were fixed for immunohistochemistry. The bottom of the panel shows an example of simultaneous DC recordings from 4 different sites in an isolated guinea pig brain. Hypoxic depressions (HD) were recorded in the electrodes located in the regions vascularized by the occluded MCA. Potentials evoked by LOT stimulation before and during the first part of ischemia (arrowhead) disappeared when HD occurred, and recovered during MCA reperfusion. Evoked potentials in the hemisphere contralateral to MCA occlusion were not altered.</p
