期刊
AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY
卷 280, 期 3, 页码 C540-C547出版社
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajpcell.2001.280.3.C540
关键词
spectroscopy; specific tension; force; weakness; aging
资金
- NIAMS NIH HHS [AR-32961] Funding Source: Medline
- NIA NIH HHS [R01 AG017768, K02 AG021626, F32 AG005815, AG-00198, AG-18156, F32 AG005815-02] Funding Source: Medline
We tested the hypothesis that low specific tension (force/cross-sectional area) in skeletal muscle from aged animals results from structural changes in myosin that occur with aging. Permeabilized semimembranosus fibers from young adult and aged rats were spin labeled site specifically at myosin SH1 (Cys-707). Electron paramagnetic resonance (EPR) was then used to resolve and quantify the structural states of the myosin head to determine the fraction of myosin heads in the strong-binding (force generating) structural state during maximal isometric contraction. Fibers from aged rats generated 27 +/- 0.8% less specific tension than fibers from younger rats (P < 0.001). EPR spectral analyses showed that, during contraction, 31.6 +/- 2.1% of myosin heads were in the strong-binding structural state in fibers from young adult animals but only 22.1 +/- 1.3% of myosin heads in fibers from aged animals were in that state (P = 0.004). Biochemical assays indicated that the age-related change in myosin structure could be due to protein oxidation, as indicated by a decrease in the number of free cysteine residues. We conclude that myosin structural changes can provide a molecular explanation for age-related decline in skeletal muscle force generation.
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