Rate and extent of leakage of a magnetic resonance contrast agent tend to be lower under isoflurane anesthesia in comparison to halothane in a rat model of embolic stroke.

Cerebral blood flow (CBF) and blood-brain barrier (BBB) permeability by arterial spin labeling (ASL)- and dynamic contrast enhanced (DCE)-magnetic resonance imaging (MRI), respectively were repeatedly measured under either halothane (N  =  5) or isoflurane (N  =  5) anesthesia in a rat stroke model of embolic occlusion of middle cerebral artery (MCA). Cerebral blood flow measurements were made after MCA embolization, following intravenous recombinant tissue plasminogen activator (rtPA) treatment at 3 hours post-ictus and again at 48 hours. Blood-brain barrier opening was examined after rtPA infusion and again at 48 hours. Data were analyzed using paired t-tests and significance considered at P < 0·05. The extent and magnitude of CBF reduction due to stroke did not differ between the two groups. Blood-to-brain forward rate constant, K(trans), a measure of BBB permeability, for an MRI contrast agent gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA), was elevated in the ipsilateral hemisphere in both cohorts. However, isoflurane-anesthetized rats exhibited a trend of lower K(trans) values at 48 hours (P  =  0·06) indicating reduced BBB damage in the ipsilateral hemisphere. The area of BBB opening followed a similar trend with the isoflurane-anesthetized group exhibiting a smaller area of BBB damage acutely and at 48 hours compared to the halothane-anesthetized group.