In vivo detection of dynamic 13C isotopomer turnover from [ U-13C]-glucose
Xu S, Zhu W, Shen J
National Institute of Mental Health
An INEPT-based 13C MRS method was used to detect dynamic isotopomer turnover in the rat brain at 11.7 T. The isotopomer patterns of both glutamate and glutamine C4 consist predominantly of a quartet (from consecutive labeling at C3, C4 and C5) and a doublet (from consecutive labeling at C4 and C5 but not at C3). A lag in the transition of glutamine C4 pattern from doublet-dominance to quartet dominance as compared to glutamate C4 was observed, which is consistent with the concept of the precursor-product relationship between glutamate and glutamine and a significant cerebral glutamate-glutamine cycle.