Effects of single and repetitive spreading depression on cerebral blood flow and glucose metabolism in cats: a PET study

To clarify the effects of spread depression (SD) on cerebral circulation an d metabolism, we elicited a single or repetitive episode of and evaluated C BF and CMRglc three-dimensionally in normal cats (n = 4, in each group) usi ng a high-resolution positron emission tomography (PET) scanner. SD was evo ked by applying KCl to the left occipital cor-tex, We then monitored DC pot ential changes with tungsten electrodes inserted into the left temporal cor tex. CBF was measured twice before and three times (immediately, 30-60 min, and 60-120 min) following KCl application using [O-15]H2O, and CMRglc was determined using 2-[F-18]fluoro-2-deoxy-D-glucose immediately following the last CBF measurement, The following results were obtained: (1) a single ep isode of SD produced a temporary: CBF increase. followed by a long-lasting hypoperfusion in the cortex with no significant changes to CBF observed in the subcortex; (2) no significant CMRglc changes were observed in either co rtical or subcortical regions following a single episode of SD; (3) a flow- metabolism uncoupling was observed in the cortical regions concurrently wit h persistent hypoperfusion; (4) repetitive SD produced significant CBF chan ges in the cortex, and (5) the cortical CMRglc increased as a result of rep eated episodes of SD, with no significant changes observed in the subcortex . Thus, we succeeded in determining three-dimensionally the effects of sing le and repetitive SD on CBF and CMRglc in cats using a high-resolution PET scanner. The present study provides the first direct evidence of CBF-CMglc uncoupling occurring concurrently with persistent hypoperfusion following S D. (C) 2000 Elsevier Science B.V. All rights reserved.