Table 3.

Metabolic rates (μmol · gm-1 · min-1) in the awake rat brain derived from the model (Gruetter et al., 2001) extended as in Figure 1 to include oxaloacetate-fumarate cycling

CMRglc(ox)VPDHVPCVgVNTVxVexEmbedded ImageEmbedded Image
13C only 0.91 ± 0.09 1.15 ± 0.17 0.18 ± 0.04 0.30 ± 0.11 0.57 ± 0.24 1.9 ± 1.2 0.21 ± 0.09 7.9 ± 1.6 16.7 ± 2.5
13C and 14C 0.92 ± 0.08 1.17 ± 0.15 0.18 ± 0.03 0.30 ± 0.09 0.45 ± 0.10 2.1 ± 1.1 0.16 ± 0.04 7.9 ± 1.5 16.9 ± 2.2
  • Values are given as mean ± SD. Glial and neuronal ATP synthesis rates were calculated for the condition in which all glucose phosphorylation occurs in glia (i.e., x = 0 in Eqs. 2, 3). Vfum was determined from the fit of 13C and 14C data combined (Vfum = 0.11 ± 0.12 μmol · gm-1 · min-1) and was set to this value when fitting the 13C data alone.