Fig. 1. Effect of isoflurane on regional cerebral blood flow (rCBF) in C57BL/6 wild-type mice before (closed column) and 45 min after (hatched column) the administration of drugs: (A ) effect of vehicle (0.9% saline); (B ) 7-nitroindazole (7-NI, 40 mg/kg, intraperitoneal), a neuronal NOS inhibitor; (C ) indomethacin (INDO, 10 mg/kg, intravenous), a nonselective cyclooxygenase inhibitor; (D ) N-methylsulfonyl-6-(2-proparglyoxyphenyl)hexanoic acid (PPOH, 20 mg/kg, intravenous), a cytochrome P450 expoxygenation inhibitor. The rCBF response was measured by laser Doppler flowmetry in the cerebral cortex in vivo during stepwise increases of isoflurane from 0.0 to 1.2, 1.8, and 2.4 vol% end-tidal concentration in α-chloralose–urethane-anesthetized, paralyzed, artificially ventilated mice. Forty-five minutes were interspersed before the stepwise increase of isoflurane concentration was repeated in the presence of the respective drug. Vehicle and indomethacin (at 2.4 vol%) had no significant impact on the isoflurane-induced cerebral hyperemia, whereas 7-NI and PPOH attenuated the response by 29%. Data are expressed as mean ± SD; n = 6–7 animals. *Significantly (P < 0.05) different from 0.0 or 1.2 vol% isoflurane. †Significantly (P < 0.05) different from 1.8 vol% isoflurane. ‡Significantly (P < 0.05) different from control.