Distefano 2012 Abstract IOC68

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Distefano G, Dube JJ, Helbling NL, Ritov VB, Stefanovic-Racic M, Toledo FGS, Ng J, Goodpaster BH, Coen PM (2012) Human skeletal muscle mitochondria respiration: The influence of aging, adiposity and aerobic fitness. MiPNet17.08.

Link: MiPNet17.08 IOC68

Distefano G, Dube JJ, Helbling NL, Ritov VB, Stefanovic-Racic M, Toledo FGS, Ng J, Goodpaster BH, Coen PM (2012)

Event: IOC68

Background: Aging is associated with reductions in skeletal muscle mitochondria function as evidenced by a decreased capacity for ATP production and mitochondrial protein content [1,2,3]. Aging is also associated with changes in body composition, including increased adiposity, and a loss of aerobic fitness. Both are factors that confound an examination of the relationship between mitochondrial function and aging per se. The objective of this study was to determine whether the respiratory properties of permeabilized skeletal muscle fibers are altered with chronological age, or more related to age associated changes in adiposity and aerobic fitness.

Methods: A total of 63 participants were assigned to one of the following groups: Young (Y, 26.9 Β± 0.9 yrs, n=30), Middle-aged (M, 41.2 Β± 2.4 yrs, n=13), or Elderly (77.7 Β± 1.1 yrs, n=20). Following an overnight fast, a percutaneous muscle biopsy of vastus lateralis was obtained. Maximal coupled (St.P), maximal non-coupled (St.E), and LEAK state (St.L) respiration was determined in saponin permeabilized muscle fiber bundles using high-resolution respirometry. VO2peak was determined by a graded exercise test. Total body fat and fat free mass were assessed by whole body DEXA.

Results: The Y group had significantly greater levels of St.P respiration (220 Β± 15 pmol O2 s-1mg-1) compared to M (166 Β± 13 pmol O2 s-1mg-1, P = 0.02) and O groups (170 Β± 13 pmol O2 s-1mg-1, P = 0.014). There was no difference in St.P respiration between M and O groups. Similar group differences were also observed for St.E and St.L respiration. The Y group exhibited a higher VO2peak (46 Β± 2.9 ml min-1kg-1) compared to M (28 Β± 1.8 ml min-1kg-1, P<0.01) and O (21 Β± 2.2 ml min-1kg-1, P<0.01) groups. When the three groups were combined, St.P respiration was positively correlated with VO2peak (R = 0.631, P<0.01), and negatively correlated with age (R = -0.324, P = 0.01), BMI (R =-0.371, P<0.01), fasting glucose (R = -0.252, P = 0.047), and fat mass (R = -0.516, P = <0.01).

Conclusions: Our data suggest that age related changes in body composition and aerobic fitness may be more important to mitochondrial dysfunction than chronological age per se.

References: 1. Petersen KF, Befroy D, Dufour S, Dziura J, Ariyan C, Rothman DL, DiPietro L, Cline GW, Shulman GI (2003) Mitochondrial dysfunction in the elderly: Possible role in insulin resistance. Science 300: 1140-1142. 2. Conley KE, Jubrias SA, Esselman PC (2000) Oxidative capacity and ageing in human muscle. J Physiol 526: 203-210. 3. Short KR, Bigelow ML, Kahl J, Singh R, Coenen-Schimke J, Raghavakaimal S, Nair KS (2005) Decline in skeletal muscle mitochondrial function with aging in humans. Proc Natl Acad Sci U S A 102: 5618-5623.

β€’ Keywords: Mitochondrial respiration, Permeabilized fibers, Skeletal muscle, Aging

β€’ O2k-Network Lab: US PA Pittsburgh Goodpaster BH

Labels: MiParea: Respiration, mt-Biogenesis;mt-density, Exercise physiology;nutrition;life style  Pathology: Aging;senescence, Obesity 

Organism: Human  Tissue;cell: Skeletal muscle  Preparation: Permeabilized tissue 

HRR: Oxygraph-2k 

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