title: Transient changes in cortical glucose and lactate levels associated with peri-infarct depolarisations, studied with rapid-sampling microdialysis.
abstract: Peri-infarct depolarisations (PIDs) contribute to infarct expansion in experimental focal ischaemia; furthermore, depolarisations propagate in the injured human brain. Glucose utilisation is increased under both conditions, and depletion of brain glucose carries a poor prognosis. We studied dynamics of cerebral glucose and lactate in relation to PID patterns in experimental stroke. The middle cerebral artery was occluded for 3 h in 23 cats under terminal chloralose anaesthesia. We used fluorescence imaging to detect occurrence of PIDs, and rapid-sampling online microdialysis (rsMD), coupled to a flow-injection assay, to examine changes in cerebral cortical extracellular glucose and lactate at intervals of 30 sec each. After 30 min' ischaemia, lactate had increased by 43.6+/-s.d. 45.9 micromol/L, and stabilised in that range for 3 h. In contrast, glucose fell only slightly initially (11.9+/-9.7 micromol/L), but progressively decreased to a reduction of 56.7+/-47.2 micromol/L at 3 h, with no evidence of stabilisation. There was a highly significant inverse relationship of frequency of PIDs with plasma glucose (P<0.001). The results also characterise a metabolic signature for PIDs for possible application in clinical work, and emphasise potential risks in the use of insulin to control plasma glucose in patients with brain injury.
authors.affiliation: Department of Clinical Neurosciences, Section of Neurosurgery, King's College, London, UK.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Hopwood
authors.forename: Mark C
authors.initials: MC
authors.lastname: Parkin
authors.forename: Elizabeth L
authors.initials: EL
authors.lastname: Bezzina
authors.forename: Martyn G
authors.initials: MG
authors.lastname: Boutelle
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Strong
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D002545:Brain Ischemia / Q000378:metabolism / Q000503:physiopathology; D002415:Cats; D013181:Cortical Spreading Depression; D004195:Disease Models, Animal; D005260:Female; D005453:Fluorescence; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D020244:Infarction, Middle Cerebral Artery / Q000503:physiopathology; D007328:Insulin / Q000494:pharmacology; D019344:Lactic Acid / Q000378:metabolism*; D008297:Male; D017551:Microdialysis / Q000295:instrumentation / Q000379:methods*
chemical_list: D001786:Blood Glucose; D007328:Insulin; D019344:Lactic Acid; D005947:Glucose