Complex activities were measured spectrophotometrically as described in Methods. All activity results are the average of 4 assays from the pooled samples ± SEM for each age group. Citrate synthase activities were used to normalize mitochondrial proteins. Activities for young (4-5 months), middle-aged (10-12 months), and old (20-26 months) WT and dwarf heart CI-CV are plotted as follows: (A) CI activity. Coefficients of variance for WT and dwarf were 7.1% and 3.7% (young), 7.7% and 6.5% (middle-age), and 6.1% and 10.5% (old), respectively. (B) CII activity. Coefficients of variance for WT and dwarf were 8.3% and 6.3% (young), 7.5% and 3% (middle-age), and 6.9% and 10.5% (old), respectively. (C) CIII activity. Coefficients of variance for WT and dwarf were 6.1% and 13% (young), 3.8% and 9.5% (middle-age), and 6.2% and 3% (old), respectively. (D) CIV activity. Coefficients of variance for WT and dwarf were 1.8% and 4.6% (young), 4.3% and 3.3% (middle-age), and 2.4% and 8.7% (old), respectively. (E) CV activity. Coefficients of variance for WT were 6.1% and 10.7% (young), 3.2% and 6.6% (middle-age), and 9.3% and 8.3% (old), respectively. * - p<0.05 compared to young, ** - p<0.001 compared to young, † - p<0.05 compared to middle-aged, †† -p<0.001 compared to middle-aged, ‡ - p<0.05 compared to WT, and ‡‡ - p<0.001 compared to WT.

Coupled enzyme activities were measured spectrophotometrically as described in Methods. All activity results are the average of 4 assays from the pooled samples ± SEM for each age group. Citrate synthase activities were used to normalize mitochondrial proteins. Activities for young (4-5 months), middle-aged (10-12 months), and old (20-26 months) WT and dwarf heart CI-III and CII-III are plotted as follows: (A) CI-CIII coupled activity. Coefficients of variance for WT and dwarf were 3.4% and 6.5% (young), 9% and 10.2% (middle-age), and 4.1% and 2.2% (old), respectively. (B) CII-CIII coupled activity. Coefficients of variance for WT and dwarf were 7.2% and 11.3% (young), 6.3% and 7.7% (middle-age), and 7.7% and 15.4% (old), respectively. * - p<0.05 compared to young, ** - p<0.001 compared to young, † - p<0.05 compared to middle-aged, ‡ - p<0.05 compared to WT, and ‡‡ - p<0.001 compared to WT.

Complex enzyme activities were measured spectrophotometrically as described in Methods. All activity results are averages of 4 assays from the pooled sample ± SEM for each age group. Citrate synthase activities were used to normalize mitochondrial proteins. Activities for young (4-5 months), middle-aged (10-12 months), and old (20-26 months) WT and dwarf pectoralis CI-CV are plotted as follows: (A) CI activity. Coefficients of variance for WT and dwarf were 8.4 % and 19.3% (young), 14.5% and 19.6% (middle-age), and 4.1% and 16.2% (old), respectively. (B) CII activity. Coefficients of variance for WT and dwarf were 6.7% and 3.7% (young), 3.5% and 7.7% (middle-age), and 11.8% and 5.1% (old), respectively. (C) CIII activity. Coefficients of variance for WT and dwarf were 6% and 7.3% (young), 9.6% and 11.3% (middle-age), and 2.8% and 5.7% (old), respectively. (D) CIV activity. Coefficients of variance for WT and dwarf were 3.2% and 5% (young), 4.9% and 5.7% (middle-age), and 3.3% and 8.7% (old), respectively. (E) CV activity. Coefficients of variance for WT and dwarf were 9.9% and 4.5% (young), 18.2% and 14.1% (middle-age), and 2.2% and 7.4% (old), respectively. * - p<0.05 compared to young, ** - p<0.001 compared to young, † - p<0.05 compared to middle-aged, †† -p<0.001 compared to middle-aged, ‡ - p<0.05 compared to WT, and ‡‡ - p<0.001 compared to WT.

CI-III and CII-III coupled enzyme activities were measured spectrophotometrically as described in Methods. All activity results are the average of 4 assays from the pooled samples ± SEM for each age group. Citrate synthase activities were used to normalize mitochondrial proteins. Activities for young (4-5 months), middle-aged (10-12 months), and old (20-26 months) WT and dwarf pectoralis CI-III and CII-III are plotted as follows: (A) CI-CIII coupled activity. Coefficients of variance for WT and dwarf were 8.2% and 6.1% (young), 7% and 12.9% (middle-age), and 4.7% and 5.4% (old), respectively. (B) CII-CIII coupled activity. Coefficients of variance for WT and dwarf were 2.9% and 6.3% (young), 6.2% and 5.9% (middle-age), and 10.2% and 2.9% (old), respectively. * - p<0.05 compared to young, ** - p<0.001 compared to young, and † - p<0.05 compared to middle-aged.

Complex enzyme activities were measured spectrophotometrically as described in Methods. All activity results are the average of 4 assays from the pooled samples ± SEM for each age group. Citrate synthase activities were used to normalize mitochondrial proteins. Activities for young (4-5 months), middle-aged (10-12 months), and old (20-26 months) WT and dwarf quadriceps ETC CI-CV are plotted as following. (A) CI activity. Coefficients of variance for WT and dwarf were 3.2 % and 15.1% (young), 9.4% and 6.3% (middle-age), and 10.5% and 9.5% (old), respectively. (B) CII activity. Coefficients of variance for WT and dwarf were 1.9% and 5.7% (young), 7.2% and 5.9% (middle-age), and 12.9% and 5.8% (old), respectively. (C) CIII activity. Coefficients of variance for WT and dwarf were 8% and 13.9% (young), 4.6% and 9.4% (middle-age), and 3.6% and 8.7% (old), respectively. (D) CIV activity. Coefficients of variance for WT and dwarfs were 5.9% and 6.9% (young), 4.6% and 9.5% (middle-age), and 10.5% and 8.7% (old), respectively. (E) CV activity. Coefficients of variance for WT and dwarfs were 6.5% and 5.1% (young), 10.2% and 13% (middle-age), and 11.6% and 8% (old), respectively. * - p<0.05 compared to young, ** - p<0.001 compared to young, † - p<0.05 compared to middle-aged, ‡ - p<0.05 compared to WT, and ‡‡ - p<0.001 compared to WT.

CI-III and CII-III coupled enzyme activities were measured spectrophotometrically as described in Methods. All activity results are the average of 4 assays from the pooled samples ± SEM for each age group. Citrate synthase activities were used to normalize mitochondrial proteins. Activities for young (4-5 months), middle-aged (10-12 months), and old (20-26 months) WT and dwarf quadriceps CI-III and CII-III are plotted as follows: (A) CI-CIII coupled activity. Coefficients of variance for WT and dwarf were 3.1% and 2.5% (young), 2.8% and 2.5% (middle-age), and 6.5% and 3.1% (old), respectively. (B) CII-CIII coupled activity. Coefficients of variance for WT and dwarf were 2.2% and 4.3% (young), 9.2% and 6.8% (middle-age), and 10.5% and 13.3% (old), respectively. * - p<0.05 compared to young, ** - p<0.001 compared to young, †† - p<0.001 compared to middle-aged, and ‡ - p<0.05 compared to WT.

Complex enzyme activities were measured spectrophotometrically as described in Methods. All activity results are the average of 4 assays from the pooled samples ± SEM for each age group. Citrate synthase activities were used to normalize mitochondrial proteins. Activities for young (4-5 months), middle-aged (10-12 months), and old (20-26 months) WT and dwarf kidney ETC CI-CV are plotted as follows: (A) CI activity. Coefficients of variance for WT and dwarf were 3.9 % and 10.8% (young), 5.6% and 9.5% (middle-age), and 4.9% and 9.2% (old), respectively. (B) CII activity. Coefficients of variance for WT and dwarf were 2.6% and 7.5% (young), 6.5% and 3.6% (middle-age), and 6.8% and 7.7% (old), respectively. (C) CIII activity. Coefficients of variance for WT and dwarf were 13.7% and 12.9% (young), 10.2% and 8.8% (middle-age), and 12.7% and 4.3% (old), respectively. (D) CIV activity. Coefficients of variance for WT and dwarf were 9.9% and 4.8% (young), 6.8% and 8% (middle-age), and 4.6% and 7.7% (old), respectively. (E) CV activity. Coefficients of variance for WT and dwarf were 5.5% and 8% (young), 3.4% and 6.1% (middle-age), and 7.5% and 9% (old), respectively. * - p<0.05 compared to young, ** - p<0.001 compared to young, † - p<0.05 compared to middle-aged, ‡ - p<0.05 compared to WT, and ‡‡ - p<0.001 compared to WT.

Coupled enzyme activities were measured spectrophotometrically as described in Methods. All activity results are the average of 4 assays from the pooled samples ± SEM for each age group. Citrate synthase activities were used to normalize mitochondrial proteins. Activities for young (4-5 months), middle-aged (10-12 months), and old (20-26 months) WT and dwarf kidney CI-III and CII-III are plotted as follows: (A) CI-CIII coupled activity. Coefficients of variance for WT and dwarf were 4.1% and 5.2% (young), 4.4% and 5.6% (middle-age), and 1.5% and 3.4% (old), respectively. (B) CII-CIII coupled activity. Coefficients of variance for WT and DW were 15.8% and 5% (young), 8% and 8.7% (middle-age), and 5.4% and 5% (old), respectively. * - p<0.05 compared to young, ** - p<0.001 compared to young, † - p<0.05 compared to middle-aged, †† - p<0.001 compared to middle-aged, ‡ - p<0.05 compared to WT, and ‡‡ - p<0.001 compared to WT.