Glucose and Ketone-Body Utilization in Young Rat Brains: A Compartmental Analysis of Isotopic Data
There have been only a few studies in which rates of glucose and ketone-body metabolism have been estimated in the brains of small, conscious animals. Most of these have used arterio-venous difference measurements, a method that requires a knowledge of the rate of blood flow through the brain, and in small, conscious animals that is difficult to determine. Moreover, the method only gives overall net uptake rates, and no estimates of the rates of the various intermediate steps can be obtained. Results of an alternative approach are described in this chapter, whereby estimates of rates of various intermediary steps of metabolism in the brain were based on a compartmental analysis of isotopic data. Animals were injected with the following labeled compounds: D-[2-14 C]-glucose, L(+)-[3-14 C]-lactate, and D(-)-3-hydroxy-[3-14C]-butyrate. These were chosen because they are the isomers preferred by the relevant enzymes in situ and the selected specific positions of the 14 C label have particular advantages for quantitative analyses (see Chapter 22 this volume).
KeywordsBlood Lactate Ketone Body Specific Radioactivity Brain Glucose Compartmental Analysis
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