Fig. 6. Histologic outcome from 10 min of severe forebrain ischemia and 5 days of recovery. In both hippocampal CA1 and the caudoputamen, 1.4% isoflurane (Isof) reduced injury relative to fentanyl-nitrous oxide (Fent/N²O). Addition of bicuculline (Bicuc) before ischemia caused a dose-dependent reversal of the effect of isoflurane in CA1 and caudoputamen. There was no effect of treatment group in the cortex. C.D.I. = crude damage index (0 = normal). a = fentanyl-nitrous oxide  versus isoflurane (  P = 0.003); b = isoflurane plus 2 mg/kg bicuculline  versus isoflurane (  P = 0.0006); c = fentanyl-nitrous oxide  versus isoflurane (  P = 0.02); d = isoflurane plus 2 mg/kg bicuculline  versus isoflurane (  P = 0.003).