Figure 2. Glucose contribution to central carbon metabolism is robust in aging C57BL/6J mice.

3 month old (n = 4) versus 24 month old (n = 4) C57BL/6J mice were infused with [U-¹³C]-glucose at 0.4 mg/min for 6 h. A, B, [M+3] fractional labeling (A) and relative levels (B) of pyruvate, lactate, and alanine in the indicated tissues. C, Relative levels of TCA cycle metabolites in the indicated tissues. D–G, Mass isotopomer distributions of citrate, succinate, and malate in plasma (D), liver (E), gastrocnemius muscle (F), and brain (G) tissues. Data are presented as mean ± SEM. Comparisons were made using a two-tailed Student’s t-test.