Whole animal oxygen consumption during CR.

<p>Oxygen consumption normalized to whole body weight (VO₂/BWT) for normal (A, D) and SirT1-null (B, E) mice was measured after 2–4 weeks (A–C) and 21–26 weeks (D–F) of CR or AL diet as indicated. RER from the same animals at 2–4 weeks (C) or 21–26 weeks (F) of CR were also obtained. Data were plotted as PRCF as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0001759#pone-0001759-g004" target="_blank">Figure 4</a>. The normal mice adapted to CR by maintaining their levels of oxygen consumption but the oxygen consumption of SirT1-null animals was higher in AL than in CR. This difference was particularly evident in older SirT1-null mice (panel E) when AL animals' oxygen consumption was very high.