Fig. 2.

¹H MRS evaluations of brain metabolites. (a) Region of interest selected for single voxel ¹H MRS of the mouse brain in vivo and post-microwave fixation. Results shown here demonstrate the effect of adequate and inadequate heat stabilization on metabolites determined retrospectively by comparing individual ex vivo to in vivo lactate levels (12 scans, 16 hs). (b) Lactate is stabilized with adequate heat (open circles, n = 4) and does not change significantly over a 16 hour scan series, but levels double by the first scan interval (60 min) with inadequate heat. (c) Residual anaerobic respiration causes a sharp decrease in NAA levels by the first scan interval when adequate heat is not applied (closed circles, n = 5). Metabolite concentrations are reported as institutional units (IU). Means at each timepoint are displayed with error bars indicating standard error of the mean