Fig. 1.

Species-dependent longevity is mediated by uncoupled respiration. Mitochondrial uncoupled respiration in the brain (A), muscle (B), kidney (C), heart (D), and liver (E) increases with age across both mice and rats. However, in general, rats exhibited significantly greater levels of uncoupled respiration compared with mice in all tissues (n = 4–8, P < 0.05; A–E). Uncoupled respiration is the ratio of palmitic acid-driven respiration to state 4 oligomycin-induced respiration. FFA, free fatty acids. ^aSignificant with respect to mice.