title: Repeated negative DC deflections in rat cortex following middle cerebral artery occlusion are abolished by MK-801: effect on volume of ischemic injury.
abstract: Following permanent occlusion of the left middle cerebral artery (MCA) in rats, electrophysiological and hemodynamic characteristics of the periinfarct border zone were investigated in sham-operated (n = 6), untreated (n = 6), and MK-801-treated (3.0 mg/kg; n = 6) animals. For this purpose, direct current potential (DC), EEG, and blood flow (laser-Doppler flowmetry) were recorded from the cortex in the periphery of the MCA territory. In sham-operated rats, a single negative cortical DC deflection was observed after electrocoagulation of the cortex, whereas in untreated MCA-occluded animals, three to eight transient DC deflections were monitored during the initial 3 h of ischemia. The duration of these cortical DC shifts gradually increased from 1.2 +/- 0.3 to 3.7 +/- 2.7 min (mean +/- SD; p less than 0.05) during this time. In animals treated intraperitoneally with MK-801 (3.0 mg/kg) immediately after MCA occlusion, the number of cortical DC shifts significantly declined to one to three deflections (p less than 0.005). The EEG of the treated animals revealed low-amplitude burst-suppression activity. In the untreated and treated experimental group, the reduction of cortical blood flow amounted to 69 +/- 25 and 49 +/- 13% of control, respectively. Despite the more pronounced cortical oligemia, MK-801 treatment resulted in a significant decrease of the volume of the ischemically injured tissue from 108 +/- 38.5 (untreated group) to 58 +/- 11.5 (p less than 0.05) mm3. Our results suggest that repetitive cortical DC deflections in the periinfarct border zone contribute to the expansion of ischemic brain infarcts.
authors.affiliation: Department of Experimental Neurology, Max Planck Institute for Neurological Research, Cologne, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Iijima
authors.forename: G
authors.initials: G
authors.lastname: Mies
authors.forename: K A
authors.initials: KA
authors.lastname: Hossmann
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001157:Arterial Occlusive Diseases / Q000150:complications; D002545:Brain Ischemia / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D002539:Cerebral Arterial Diseases / Q000150:complications; D002540:Cerebral Cortex / Q000187:drug effects / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology; D016291:Dizocilpine Maleate / Q000494:pharmacology*; D004569:Electroencephalography / Q000187:drug effects; D008297:Male; D051381:Rats
chemical_list: D016291:Dizocilpine Maleate