The mammalian brain has very small reserves of carbohydrates, which under normal circumstances are the preferred sources of energy in vivo. Thus, the cerebral cortex contains glucose at l–l.5 μmol/g fresh weight and a little more of the equivalent amount of glucose stored as glycogen (McIlwain and Bachelard, 1985). On death, very rapid rates of anaerobic metabolism continue postmortem, so within a few seconds, cerebral glucose in the mouse or rat brain falls to undetectable levels; glycogen is then mobilized, and the total stores of readily utilizable carbohydrate are severely depleted in less than 1 min. Concomitantly with these decreases, lactate increases to very high levels of some 3-to 4-fold normal within 1 min (Lowry et al., 1964). Other carbohydrates or their derivatives occur in minute amounts and do not contribute significantly to this process.