The Relation Between Amino Acid and Glucose Metabolism in Developing Brain

摘要

The metabolism of the brain is characterized by emphasis on carbohydrate as the energy source and the rate of the energy metabolism increases during the neural excitation. It is generally believed that the control steps in glycolytic pathway are those concerned with phosphorylation of glucose (hexokinase) and fructose-6-phosphate(phosphofructokinase). Although the data presented in this report are consistent with this consideration, they clearly indicate that, in addition to the above two, the step catalyzed by pyruvate kinase is rate-limiting and controlling for glycolysis in brain cortex slices. Pyruvate kinase in brain tissue seems to be strongly inhibited in some way which is related to the cellular structures and this inhibited activity is regulated by the ionic milieu. The changes in the intermediate levels of the glycolytic pathway in the brain cortex slices by the addition of high potassium in the incubation medium were characterized by decreases in glucose-6-phosphate and fructose-6-phosphate, and by increases of fructose diphosphate, triose phosphates and lactate. These changes were similar to those induced by ischemia in vivo brain. (Author)