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 and metabolism, we elicited a single or repetitive episode of and evaluated CBF and CMRglc three-dimensionally in normal cats (n = 4, in each group) using a high-resolution positron emission tomography (PET) scanner. SD was evoked by applying KCl to the left occipital cor-tex, We then monitored DC potential changes with tungsten electrodes inserted into the left temporal cortex. 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 episode 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 cortical or subcortical regions following a single episode of SD; (3) a flow-metabolism uncoupling was observed in the cortical regions concurrently with persistent hypoperfusion; (4) repetitive SD produced significant CBF changes in the cortex, and (5) the cortical CMRglc increased as a result of repeated episodes of SD, with no significant changes observed in the subcortex. Thus, we succeeded in determining three-dimensionally the effects of single 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 SD. (C) 2000 Elsevier Science B.V. All rights reserved.