Fig. 1. Regional cerebral blood flow (CBF) values for rats 10 min before (Pre), during (Intra), or 30 min after ischemia (Post). Rats were anesthetized with either fentanyl–N2O or isoflurane (with or without 2.5mg intravenous trimethaphan [TMP] at onset of ischemia for Intra and Post measurements). No differences were present among groups. Bilateral carotid occlusion and reduction of mean arterial pressure to 30 mmHg caused a marked blood flow reduction to 5% or less of baseline values (P < 0.001) in the cortex, caudoputamen, hippocampus, and thalamus, whereas flow in the brain stem and cerebellum was preserved. Reperfusion at 30 min was associated with a 35–50% restoration of flow to baseline values in the ischemic structures.