Age-Related Changes in Activities of Mitochondrial Electron Transport Complexes in Various Tissues of the Mouse

Aging-induced alterations in gene transcripts and functional activity of mitochondrial oxidative phosphorylation complexes in the heart

“…5B) as determined by the reduction of ubiquinone-2 by succinate (Darley-Usmar et al, 1987). These findings are similar to previous reports demonstrating no age-associated change in the activity of SDH in mitochondria isolated from rat skeletal muscle as well as from mice kidneys and liver (Kwong and Sohal, 2000;Sugiyama et al, 1993;Yarian et al, 2006).…”

“…Complex II activity was measured as the rate of reduction of ubiquinone-2 by succinate (Abs 600 nm) and calculated using the extinction coefficient of 21/mM/cm (Darley-Usmar et al, 1987). Complex III activity was measured by following the increase in absorbance at 550 nm due to the reduction of ferricytochrome c after adding 6 µl of decylubiquinol (Kwong and Sohal, 2000). Decylubiquinol used in this assay was prepared as previously described (Trumpower and Edwards, 1979).…”

Age-related alterations in oxidatively damaged proteins of mouse heart mitochondrial electron transport chain complexes

“…CI-III and CII-III coupled assays were performed as described [9,37]. Briefly, CI-CIII activity was measured at 550 nm (ε = 19 mM −1 cm −1 ) in 1 mL reaction mixture initially incubated at 30°C for 10 minutes containing reaction buffer (50 mM Potassium Phosphate, pH 7.4, 5 mM MgCl 2 and 1 mg/mL BSA), 7-8 μg of sonicated mitochondria, 350 μM NADH and 2 mM KCN.…”

Changes in Mitochondrial Status Associated with Altered Ca2+Homeostasis in Aged Cerebellar Granule Neurons in Brain Slices

“…Aged mitochondria display a significant reduction in the activity of the various electron-transport complexes and an age-associated alteration in the mitochondrial membrane potential (Hagen et al, 1997;Kwong and Sohal, 2000). These changes are seen as a consequence of a vicious cycle of accumulated mitochondrial oxidative stress and damage of the mitochondrial DNA (Lenaz, 1998;.…”

“…In the brain, the activity of the complex III of the respiratory chain, considered crucial for the activity of the entire oxidative phosphorylation system, was significantly decreased in old mice (Kwong and Sohal, 2000); measurements in hepatocytes showed a marked degree of age-related decline of the average mitochondrial membrane potential (Hagen et al, 1997). The observations presented here tell a similar story, but f uture experiments are required to determine whether the changes observed in aged neurons are attributable to mitochondrial DNA lesions/mutations (Cortopasi and Wong, 1999) or to other structural or f unctional changes .…”