title: Exercise by lifelong voluntary wheel running reduces subsarcolemmal and interfibrillar mitochondrial hydrogen peroxide production in the heart.
abstract: Evidence suggests that mitochondrial dysfunction and oxidant production, in association with an accumulation of oxidative damage, contribute to the aging process. Regular physical activity can delay the onset of morbidity, increase mean lifespan, and reduce the risk of developing several pathological states. No studies have examined age-related changes in oxidant production and oxidative stress in both subsarcolemmal (SSM) and interfibrillar (IFM) mitochondria in combination with lifelong exercise. Therefore, we investigated whether long-term voluntary wheel running in Fischer 344 rats altered hydrogen peroxide (H2O2) production, antioxidant defenses, and oxidative damage in cardiac SSM and IFM. At 10-11 wk of age, rats were randomly assigned to one of two groups: sedentary and 8% food restriction (sedentary; n = 20) or wheel running and 8% food restriction (runners; n = 20); rats were killed at 24 mo of age. After the age of 6 mo, running activity was maintained at an average of 1,145 +/- 248 m/day. Daily energy expenditure determined by doubly labeled water technique showed that runners expended on average approximately 70% more energy per day than the sedentary rats. Long-term voluntary wheel running significantly reduced H2O2 production from both SSM (-10.0%) and IFM (-9.6%) and increased daily energy expenditure (kJ/day) significantly in runners compared with sedentary controls. Additionally, MnSOD activity was significantly lowered in SSM and IFM from wheel runners, which may reflect a reduction in mitochondrial superoxide production. Activities of the other major antioxidant enzymes (glutathione peroxidase and catalase) and glutathione levels were not altered by wheel running. Despite the reduction in mitochondrial oxidant production, no significant differences in oxidative stress levels (4-hydroxy-2-nonenal-modified proteins, protein carbonyls, and malondialdehyde) were detected between the two groups. The health benefits of chronic exercise may be, at least partially, due to a reduction in mitochondrial oxidant production; however, we could not detect a significant reduction in several selected parameters of oxidative stress.
authors.affiliation: Univ. of Florida, College of Medicine, Dept. of Aging and Geriatric Research, Genomics and Biomarkers Core Institute on Aging, Biochemistry of Aging Laboratory, Gainesville, FL 32608, USA.
authors.forename: Sharon
authors.initials: S
authors.lastname: Judge
authors.forename: Young Mok
authors.initials: YM
authors.lastname: Jang
authors.forename: Anthony
authors.initials: A
authors.lastname: Smith
authors.forename: Colin
authors.initials: C
authors.lastname: Selman
authors.forename: Tracey
authors.initials: T
authors.lastname: Phillips
authors.forename: John R
authors.initials: JR
authors.lastname: Speakman
authors.forename: Tory
authors.initials: T
authors.lastname: Hagen
authors.forename: Christiaan
authors.initials: C
authors.lastname: Leeuwenburgh
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000375:Aging / Q000502:physiology; D000818:Animals; D001824:Body Constitution / Q000502:physiology*; D005080:Exercise Test; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008019:Life Style; D008297:Male; D008929:Mitochondria, Heart / Q000378:metabolism*; D009043:Motor Activity / Q000502:physiology*; D018384:Oxidative Stress / Q000502:physiology; D010805:Physical Conditioning, Animal / Q000379:methods*; D005082:Physical Exertion / Q000502:physiology*; D051381:Rats; D011916:Rats, Inbred F344; D012508:Sarcolemma / Q000378:metabolism*; D014836:Volition / Q000502:physiology
chemical_list: D006861:Hydrogen Peroxide