3-HYDROXYBUTYRATE AIDS THE RECOVERY OF THE ENERGY-STATE FROM AGLYCAEMIC HYPOXIA OF ADULT BUT NOT NEONATAL RAT-BRAIN SLICES

The level of phosphocreatine (PCr) and the intracellular pH (pH(i)) of superfused cortical brain slices from adult or 10-day-old rats were m onitored using P-31 NMR. When the glucose in the superfusing medium wa s replaced by 3-hydroxybutyrate (3HB), there was a significant reducti on in PCr of the adult but not the neonatal slices. The level of PCr o f the adult slices was reduced by a greater amount by aglycaemic hypox ia compared with the neonatal brain slices and pH(i) was decreased by the same amount. After aglycaemic hypoxia, the levels of PCr of the ne onatal slices recovered to the same extent when perfused with glucose or 3HB alone or a mixture of glucose and 3HB. The recovery of the PCr was significantly more in the neonatal than the adult brain slices wit h glucose alone after aglycaemic hypoxia, whereas pH(i) returned to co ntrol levels in both tissue types and with all substrates. The relativ e recovery of the PCr of the adult slices after aglycaemic hypoxia was the same with either 3HB or glucose. However, if glucose and 3HB were applied together, recovery of PCr was significantly improved compared with glucose alone.