The opium alkaloid papaverine (PPV) Causes vasodilatation of the cerebral arteries through direct action on smooth muscle that reduces the constriction of smooth muscle. Intra-arterial papaverine (IAP) has been used widely to increase the regional cerebral blood flow in order to reverse the cerebral vasospasm that occurs during endovascular procedures. IAP-induced seizures have been reported, although PPV has anticonvulsive effects. This study determined the effects of LAP on electrocorticography (ECoG) in the ketamine anesthetized rats. We used 24 Sprague-Dawley male rats weighing 200-250 g. The animals were divided randomly into four groups: three treatment groups (groups 1-3) and a control (group,4). Groups 1, 2, and 3 were given 1, 7, and 14 mg/kg IAP, respectively. The ECoG was compared across groups. Our results indicate(] that IAP did not cause seizures and that it decreased the frequency of ketamine-induced epileptiform activity in the 14 mg/kg group. Crown Copyright (C) 2008 Published by Elsevier Ireland Ltd. All rights reserved.