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Recent Reviews, F1000 Factor 6.0

Mitochondrial functional impairment with aging is exaggerated in isolated mitochondria compared to permeabilized myofibers. Picard M, Ritchie D, ..., Taivassalo T, Hepple RT. Aging Cell. 2010 Dec; 9(6):1032-46

Evaluated by | David Marcinek and Kevin Conley, University of Washington, United States of America

Mitochondrial dysfunction in aged skeletal muscle: the answer depends on how you ask the question. A comparison of isolated mitochondria vs. permeabilized muscle fibers indicates that isolated mitochondria assays may exaggerate the extent of mitochondrial dysfunction with age.

The extent of mitochondrial dysfunction in aged muscle remains controversial. The study by Picard et al. addresses this controversy by examining what effect the approach used to measure mitochondrial function has on the conclusions. They compare the effects of aging on mitochondrial function in isolated mitochondria and permeabilized fiber bundles from rat gastrocnemius muscle. They found significant decreases in mitochondrial enzyme activities, electron transport chain protein expression and respiration in mitochondria isolated from aged muscle. Isolated mitochondria also demonstrated increases in sensitivity to opening of the mitochondrial permeability transition pore (mPTP) and H2O2 emission per O2 consumed with age. In permeabilized muscle fibers, the effects of age were reduced or absent for all parameters examined. These results suggest that mitochondria from aged muscle are more sensitive to isolation-induced damage than those from young muscle. This greater sensitivity may lead to exaggeration of the extent of dysfunction when measured in isolated mitochondria. Picard et al. demonstrate that both qualitative and quantitative measures of the effect of age on mitochondrial function are dependent on the approach. Thus, some of the age-induced dysfunction reported in the literature may actually be due to greater susceptibility of aged mitochondria to isolation procedures.

Evaluated 12 November 2010