Fig. 3.

Unchanged muscle morphology or function in mice with combined and tamoxifen-inducible skeletal muscle-specific overexpression of sirtuin 1 (SIRT1) and knockout of general control of amino acid synthesis 5 (GCN5) (dTG). Citrate synthase (A) and complex IV (CIV; B) activity in wild-type (WT) and dTG muscle (n = 7/genotype). C: respiratory flux normalized to muscle fiber weight in the presence of malate + octanoylcarnitine (M+Octc; leak respiration in the absence of adenylates), ADP, cytochrome c (CytC; mitochondrial integrity), pyruvate (Pyr), glutamate [Glut; complex I (CI) capacity], succinate [Succ; complex I + complex II (CII) capacity], carbonyl cyanide-4-(trifluoromethoxy)phenylhydrazone (FCCP; uncoupled maximal respiration), rotenone (Rot; complex II capacity), and antimycin A (Ama; residual oxygen consumption) (WT n = 10, dTG n = 7). D: representative images of wheat germ agglutinin-stained tibialis anterior muscle cross sections. E: quantification of fiber cross-sectional area, presented as %fibers within each size-range (n = 4/genotype). Peak twitch tension (F), time to peak tension (G), and half-relaxation time for a twitch contraction (H) in the 5th toe (EDL) muscle from dTG and WT mice (n = 7–8/genotype). Peak tetanic tension (I) and force-frequency curve (J) in the 5th toe EDL muscle from dTG and WT mice (n = 7–8/genotype). Data are reported as means ± SE. *P < 0.05 vs. WT. A, B, F–I: unpaired Student’s t test; C, E, J: 2-way ANOVA with Bonferroni’s multiple comparison test.