One of the serious problems that occurs after cardiopulmonary resuscitation is brain posthypoxic/ischemic deoxygenation. However, there has been no report concerning the effect of isoflurane (ISO) on the brain oxygenation during hypoxia-reoxygenation in relation to cell adhesion molecules (CD11b) in polymorphonuclear leukocyte. Rats were anesthetized with a low concentration of ISO (0.5 MAC: low ISO) or high concentration of ISO (1.5 MAC: high ISO) and brain oxygenation was detected by near infrared spectroscopy during 10-min hypoxia (5% O(2)) and a subsequent 120-min reoxygenation period. Hypoxia induced a decrease in oxyhemoglobin (HbO(2)) and an increase in deoxyhemoglobin (Hb). Reoxygenation induced a significant decrease in total hemoglobin (tHb) and HbO(2) with low ISO, but not with high ISO. The changes in Hb were minimal during reoxygenation in both groups. CD11b increased during reoxygenation with low ISO anesthetization, but not with high ISO. A significant negative correlation was observed between CD11b and two of the measured oxyparameters, HbO(2) and tHb, during reoxygenation at low ISO, but not at high ISO. These findings suggest that brain deoxygenation during hypoxia-reoxygenation is partly related to the expression of CD11b. We conclude that ISO modifies the brain circulation at least in part through attenuating the expression of CD11b during hypoxia-reoxygenation.