Blood glucose as a predictive measure for central nervous system oxygen toxicity in conscious rats

Blood glucose concentration was measured during continuous electrocorticographic (ECoG) recording in conscious rats exposed to 3 and 5 atmosphere absolute oxygen (ATA O2). The preconvulsive oxygen-induced ECoG changes included increased slow wave activity in delta range, followed by the appearance of successive paroxysmal electrical discharges. A correlation between increases in blood glucose concentration and ECoG changes was observed at both 3 and 5 ATA O2. No significant changes in blood glucose concentration were found in the absence of the ECoG changes. Equivalent periods of exposure to N2-O2 normoxic pressures of 1, 3, and 5 ATA did not produce changes either in ECoG or blood glucose concentration. It is therefore considered possible that an increase in blood glucose concentration may be a useful predictive measure of the ECoG manifestations of oxygen toxicity in conscious unrestrained rats. The possible mechanisms for increase in blood glucose concentration during development of brain oxygen toxicity are discussed.