Changes in metabolites of the energy reserves in individual layers of mouse cerebral cortex and subjacent white matter during ischaemia and anaesthesia

The distribution of glucose, glycogen, ATP, P-creatine and inorganic phosphate was measured in layers I, III, IV, V and VI of cerebral cortex and subjacent white matter of mouse brain. ATP, P-creatine and inorganic phosphate were evenly distributed in all regions examined, whereas levels of glucose and glycogen were higher in white matter than the average for the other layers. Anaesthesia increased levels of glucose and P-creatine in layers I and V and subjacent white matter (other layers were not examined). Anaesthesia doubled the level of glycogen in molecular layer I with lesser increases in layers III, IV, V and VI, but with no change in white matter from the unanaesthetized control value. The metabolic rates in the individual layers were estimated from the rates of expenditure of energy reserves during total ischaemia. In non-anaesthetized mice, white matter had a higher metabolic rate than either layer I or V. Anaesthesia reduced the metabolic rates in all layers; however, the largest reduction occurred in subjacent white matter (86 per cent), with reductions of 54 per cent and 76 per cent respectively in layers I and V.