Simplified 13C Metabolic Modeling for Simplified Measurements of Cerebral TCA Cycle Rate in Vivo

Julien Valette¹, Fawzi Boumezbeur¹, Vincent Lebon^1,2

¹³C NMR spectroscopy is a unique tool to measure cerebral TCA cycle rate in vivo. The measurement relies on metabolic modeling of glutamate C3 and C4 enrichment time-courses during a ¹³C-glucose i.v. infusion. Classical metabolic models require as additional input functions the plasma glucose and ¹³C-glucose time-courses, as well as the knowledge of Michaelis-Menten kinetics parameters governing passage through the blood brain barrier. It is shown in the present work that metabolic modeling can be simplified in a manner that these additional inputs are not required anymore, significantly simplifying the measurement of cerebral TCA cycle rate in vivo.