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Bioenergetics of aging skeletal muscle.

机译：骨骼肌衰老的生物能。

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摘要

Phosphorous magnetic resonance spectroscopy was used to study the bioenergetics of skeletal muscle, with specific focus on the effects of senescence. In study 1 I found that the capacity for oxidative phosphorylation was unimpaired with old age. Furthermore, glycolytic flux was higher in young men, while older men relied more on oxidative phosphorylation. In addition to demonstrating unimpaired mitochondrial function with age, the results from this study raised the question of whether older adults exhibit impaired glycolytic capacity or an ability to adequately meet the energetic demands without using anaerobic glycolysis to its full potential. In studies 2 and 3, I investigated these possibilities by studying bioenergetics during free-flow (FF) and ischemic (ISC) contractions in young and older subjects.; In study 2 12 younger subjects performed FF and ISC ankle dorsiflexion with measures of muscle energetics using 31P-MRS. The overall aim of this study was to investigate the effects of ischemia on fatigue and ATP synthesis. Although fatigue was more pronounced ISC than FF, ATP supply and demand were matched under both conditions. The balance between ATP supply and demand was maintained, not through increased reliance on anaerobic glycolysis, but through increased metabolic economy and decreased rates of ATP hydrolysis. Secondary to the main findings of this study, I also provide evidence in support of a glycolytic contribution to phosphocreatine recovery in the absence of muscle contraction: a finding that conflicts with the common dogma that phosphocreatine recovery is an entirely oxidative process.; The aim of study 3 was to apply the same protocol used in study 2 to investigate the metabolic adaptability of young and older skeletal muscle under conditions where oxidative phosphorylation is negligible. As expected, glycolytic flux was lower in old compared to young during FF, however, glycolytic flux in older adults increased to a level similar to the young during ISC, suggesting that the capacity for anaerobic glycolysis in vivo remains intact in aged muscle. Furthermore, the results point to an age-related increase in metabolic economy as a mechanism that may allow older muscle to engage in maximal work with lower glycolytic flux compared to young.
机译：磷磁共振波谱法用于研究骨骼肌的生物能学，尤其侧重于衰老的影响。在研究1中，我发现氧化磷酸化的能力不会随着年龄的增长而受损。此外，年轻男性的糖酵解通量更高，而老年男性更多地依赖于氧化磷酸化。除了证明线粒体功能不会随着年龄的增长而受损外，这项研究的结果还提出了一个问题，即老年人是否表现出受损的糖酵解能力或在不充分利用厌氧糖酵解能力的情况下充分满足能量需求的能力。在研究2和3中，我通过研究年轻和老年受试者在自由流动（FF）和缺血（ISC）收缩期间的生物能学，研究了这些可能性。在研究2中，有12名年轻受试者使用31P-MRS对FF和ISC踝背屈进行了肌肉能量测定。这项研究的总体目的是研究缺血对疲劳和ATP合成的影响。尽管疲劳程度比FF更为明显，但在两种情况下ATP的供求是匹配的。维持ATP供求之间的平衡，不是通过增加对厌氧糖酵解的依赖，而是通过增加代谢经济性和降低ATP水解速率来实现的。在这项研究的主要发现之后，我还提供了证据，支持在没有肌肉收缩的情况下糖酵解对磷酸肌酸恢复的贡献：这一发现与普通教条相抵触，即磷酸肌酸的恢复完全是氧化过程。研究3的目的是应用研究2中使用的相同方案研究在氧化磷酸化可忽略不计的条件下年轻和年长骨骼肌的代谢适应性。不出所料，在FF期间，老年人的糖酵解通量要比年轻人低，但是，在ISC期间，老年人的糖酵解通量增加到与年轻人相似的水平，这表明在老年肌肉中，体内厌氧糖酵解的能力仍然完好无损。此外，结果表明，与年龄相关的代谢经济增长是一种机制，与年轻相比，该机制可以使老年肌肉以较低的糖酵解通量参与最大的工作。

著录项

  • 作者

    Lanza, Ian R.;

  • 作者单位

    University of Massachusetts Amherst.;

  • 授予单位 University of Massachusetts Amherst.;
  • 学科 Chemistry Biochemistry.; Health Sciences Recreation.
  • 学位 Ph.D.
  • 年度 2007
  • 页码 259 p.
  • 总页数 259
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 生物化学;预防医学、卫生学;
  • 关键词

  • 入库时间 2022-08-17 11:39:56

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