FIGURE 7.

Quantification of NAAG and NAAG₂ in mouse tissues. Methanol extracts were prepared form the indicated brain regions/tissues. Note that the forebrain samples lacked part of the cortex of one hemisphere, as cortex samples were analyzed separately. NAAG₂ (A) and NAAG (B) concentrations were determined by ESI-MS (black bars) (see Fig. 6). In addition, NAAG concentrations were determined by HPLC in the same extracts (gray bars). Both methods gave similar results. Neither NAAG nor NAAG₂ were detectable in liver. The detection limit (indicated by a dotted line) for NAAG₂ was 0.8 nmol/g of tissue (wet weight). The detection limit for NAAG was 9.4 (HPLC method) and 0.9 (ESI-MS method) nmol/g of tissue (wet weight). Shown are the mean ± S.D. (n = 4) of four independent experiments. N.D., not determined.