The energy aspect of transmitter glutamate turnover

Assuming a flux of transmitter Glu to astrocytes, which is at most 30% of the cerebral TCA cycle rate, we have that 3% of the energy extracted from serum glucose is consumed in the handling of transmitter Glu. 

The clinical and experimental use of radiolabeled glucose and 2-deoxyglucose in PET studies and autoradiography rests on the assumption that cerebral activity increases the consumption of ATP, which in turn necessitates an increase in uptake and metabolism of 

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