Effect of nizofenone on pyramidal response, electrocorticogram and regional cerebral blood flow following recirculation after complete global brain ischemia in cats

Abstract

Effect of nizofenone on pyramidal response (PR), electrocorticogram (ECoG) and regional cerebral blood flow (rCBF) following recirculation after complete global brain ischemia was compared with that of pentobarbital in gallamine-immobilized cats. The basilar artery and the branches of both carotid arteries (superior thyroid artery, dorsal muscular branch, internal carotid artery, occipital artery and ascending pharyngeal artery) were all ligated. The cats were subjected to complete brain ischemia by occluding both common carotid arteries for 45 min, followed by 180 min recirculation. rCBF of the cortex (suprasylvian gyrus) and the internal capsule was monitored by the hydrogen clearance method. Blood gases were regulated within a range determined previously in freely-moving cats throughout the experiment. Nizofenone (1 mg/kg, i.v.) facilitated the recovery of PR and ECoG, and it inhibited the phenomenon of secondary suppression evidenced by interruption and reversion of the recovery process. rCBF showed good recovery throughout the recirculation period. Pentobarbital (20 mg/kg, i.v.) facilitated the recovery of PR during the early period of recirculation, but secondary suppression of PR, associated with the decline of rCBF, was evident. These results suggest that the ameliorative effect of nizofenone on the recovery of neuronal functions is due to its ability to protect neurons against ischemic anoxia and to prevent interruption of postischemic circulation, and also the good recovery of rCBF is due to its ability to protect vasculature against ischemic anoxia.