Influence of cerebral circulation on measurement of the cerebral glucose metabolic rate by 14C-deoxyglucose method.

概要

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The potential influence of the cerebral circulation on measurements of the cerebral glucose metabolic rate by the 14C-deoxyglucose (DG) method originally developed by Sokoloff et al. was evaluated. Their definition of the transport rate constants for hexose by the Michaelis-Menten equation is expected to be theoretically valid as long as the cerebral extraction fraction of glucose (E) remains below 0.18. However, the present computer-simulation study revealed that E may be higher than 0.18 at a cerebral plasma flow (F) of less than 0.70ml/g/min, if Vmax (the maximum transendothelial transport rate of glucose)=F+2 or Vmax=3.5xF+0.7 is assumed based on the studies of Cremer et al. or Gjedde and Diemer. The definition of the transport rate constants for hexose was therefore modified using an exponential equation to incorporate the flow factor. A comparison was made between Sokoloff et al.'s method and the modified method employing the flow-dependent rate constants as defined above. It became clear that Sokoloff et al.'s method using the normal rate constants can significantly overestimate the glucose metabolic rate at a cerebral plasma flow (F) of less than 0.10ml/g/min, while only a minimal error was noted at F higher than 0.30ml/g/min. These findings suggest that any application of the 14C-DG method to the brain suffering from low perfusion should be carefully designed.
The Keio Journal of Medicineの論文