Single skeletal muscle fiber elastic and contractile characteristics in young and older men.
The current investigation was designed to: (a) assess the impact of aging on elastic characteristics of single skeletal muscle fibers from young (N = 6) and older men (N = 6); and (b) correlate the potential changes, with the fiber contractile properties. Chemically skinned single muscle fibers (n = 235) from vastus lateralis muscle were maximally activated. Maximal force and cross-sectional area were measured, and specific force calculated. The slack test was used to measure maximal unloaded shortening velocity. A quick release of 0.15% of fiber length was applied to determine instantaneous stiffness. The myosin heavy chain isoform composition of each single fiber was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Aging induces changes in both fiber elasticity (i.e., increased instantaneous stiffness) and contractility (i.e., reduced specific force and unloaded shortening velocity) in type I and IIa fibers. However, the changes in fiber stiffness may not directly influence contractile characteristics alterations.
Ochala
Julien
J
Muscle Cell Physiology Laboratory, Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, and Harvard Medical School, Boston, Massachusetts, USA. julien.ochala@neurofys.uu.se
Frontera
Walter R
WR
Dorer
David J
DJ
Van Hoecke
Jacques
J
Krivickas
Lisa S
LS
D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D004548:Elasticity; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D018656:Muscle Fibers, Fast-Twitch / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000502:physiology*; D018657:Muscle Fibers, Slow-Twitch / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D018995:Myosin Heavy Chains / Q000378:metabolism; D020033:Protein Isoforms / Q000378:metabolism
D020033:Protein Isoforms; D018995:Myosin Heavy Chains