Brain intermediary metabolism in vivo: Changes with carbon dioxide, development, and seizures

This chapter reviews selected aspects of brain intermediary metabolism in vivo, with a focus on the recent developments in methodology and on changes found during development, seizures, and respiratory acidosis. The chapter discusses that carbon dioxide (CO₂) levels play an important role in normal functioning of the central nervous system (CNS). Increased neuronal activity requires additional energy from oxidative phosphorylation, which raises the CO₂ level in the milieu of the active neurons. This increased CO₂ could then function to regulate local metabolism in two ways,(1) by causing an increase in local cerebral blood flow, it increases the flow of oxygen and glucose towards, and the movement of CO₂ away from the active neurons, and (2) by inhibiting glycolysis, it slows the rate of development of an intracellular lactic acidosis, which may occur in response to a temporary imbalance between the rate of glycolysis and that of pyruvate oxidation. Metabolic consequences of the carbon dioxide treatment have important implications for investigators studying the effects of a variety of CNS depressants on energy metabolism.