The effect of aging on human skeletal muscle mitochondrial and intramyocellular lipid ultrastructure.
The purpose of this study was to determine whether ultrastructural changes in intramyocellular lipid (IMCL) and mitochondria occur with aging. Muscle samples were analyzed from 24 young and 20 old, equally active, individuals for IMCL and mitochondria quantity and size as well as their association. Old men had larger IMCL droplets than all other groups in the total muscle area. Old individuals showed higher IMCL content in the subsarcolemmal area. Young participants had a greater number of mitochondria compared with old participants in both fiber regions and greater enzyme activities of cytochrome c oxidase and citrate synthase. The fraction of IMCL touching mitochondria was lowest in old women in the total area and in old men in the subsarcolemmal region. In summary, older adults have larger IMCL droplets, fewer mitochondria, and a lower proportion of IMCL in contact with mitochondria. These factors likely contribute to age-related reductions in mitochondrial function and lipid metabolism.
Crane
Justin D
JD
Department of Pediatrics and Medicine, McMaster University, 1200 Main Street West, Hamilton, Ontario, Canada.
Devries
Michaela C
MC
Safdar
Adeel
A
Hamadeh
Mazen J
MJ
Tarnopolsky
Mark A
MA
D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism* / Q000473:pathology; D015444:Exercise; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D050356:Lipid Metabolism; D008055:Lipids / Q000032:analysis; D008297:Male; D008875:Middle Aged; D008931:Mitochondria, Muscle / Q000502:physiology / Q000648:ultrastructure*; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism*; D001678:Organelle Biogenesis; D018384:Oxidative Stress; D047493:PPAR alpha / Q000235:genetics; D047495:PPAR gamma / Q000235:genetics; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D013482:Superoxide Dismutase / Q000235:genetics; D000072105:Superoxide Dismutase-1; D000099156:Superoxide Dismutase 2
D008055:Lipids; D047493:PPAR alpha; D047495:PPAR gamma; D011451:Prostaglandin-Endoperoxide Synthases; D012333:RNA, Messenger; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D000099156:Superoxide Dismutase 2; C000606290:SOD1 protein, human