Increased contact between lipid droplets and mitochondria in skeletal muscles of male elite endurance athletes.

IF 5 2区 生物学 Q2 CELL BIOLOGY
Joachim Nielsen, Kristine Grøsfjeld Petersen, Martin Eisemann de Almeida, Sam O Shepherd, Britt Christensen, Maria Houborg Petersen, Kurt Højlund, Niels Ørtenblad, Kasper Degn Gejl
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Abstract

Endurance athletes exhibit higher skeletal muscle mitochondrial and lipid droplet (LD) content compared to recreationally active individuals, along with greater whole-body oxygen uptake and maximal fat oxidation rates. In this study, we investigated if these differences manifest in a greater LD-mitochondria contact and how this may relate to the organelles' size, shape, and numerical densities. We obtained skeletal muscle biopsies from 17 male elite triathletes and road cyclists and 7 recreationally active men. Using quantitative transmission electron microscopy, we found that the endurance athletes had 2-3-fold greater LD-mitochondria total contact length than the recreationally active individuals. This was related to higher numerical densities of both mitochondria (+30%) and LDs (+100%) in the intermyofibrillar space. Adding data from untrained individuals with equally high intermyofibrillar LD density as the endurance athletes revealed a 24% greater total LD-mitochondria contact length in the endurance athletes. We observed small trivial differences in shape of both organelles between populations. However, large mitochondrial profiles were more elongated and irregular in shape than small mitochondrial profiles, while large LD profiles were more circular and less irregular than small LD profiles. Within athletes, large intermyofibrillar LD profiles correlated (r=0.72) with a high fraction of PLIN5-positive LDs and their maximal fat oxidation rate was positively associated with an interaction between the profile size of both intermyofibrillar LDs and mitochondria. In conclusion, male endurance athletes have a greater LD-mitochondria contact than recreationally active and untrained individuals. This muscular phenotype is restricted to the intermyofibrillar space and to fibers rich in mitochondria.

男性优秀耐力运动员骨骼肌中脂滴与线粒体接触增加。
耐力运动员表现出更高的骨骼肌线粒体和脂滴(LD)含量,以及更大的全身摄氧量和最大脂肪氧化率。在这项研究中,我们研究了这些差异是否表现在更大的ld -线粒体接触中,以及这与细胞器的大小、形状和数值密度之间的关系。我们对17名优秀的男性铁人三项运动员和公路自行车运动员以及7名娱乐活跃的男性进行了骨骼肌活检。通过定量透射电子显微镜,我们发现耐力运动员的ld -线粒体总接触长度比娱乐活动个体大2-3倍。这与肌纤维间间隙线粒体(+30%)和ld(+100%)的数值密度较高有关。加入与耐力运动员同样高的肌纤维间LD密度的未训练个体的数据显示,耐力运动员的LD-线粒体总接触长度比耐力运动员高24%。我们观察到两个细胞器在不同种群的形状上有细微的差别。然而,大的线粒体谱比小的线粒体谱更细长和不规则,而大的LD谱比小的LD谱更圆,更不不规则。在运动员中,大的肌纤维间LD谱与plin5阳性LD的高比例相关(r=0.72),他们的最大脂肪氧化率与肌纤维间LD谱和线粒体之间的相互作用呈正相关。总之,男性耐力运动员的ld -线粒体接触比娱乐活动和未训练的个体更大。这种肌肉表型局限于肌纤维间隙和富含线粒体的纤维。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
9.10
自引率
1.80%
发文量
252
审稿时长
1 months
期刊介绍: The American Journal of Physiology-Cell Physiology is dedicated to innovative approaches to the study of cell and molecular physiology. Contributions that use cellular and molecular approaches to shed light on mechanisms of physiological control at higher levels of organization also appear regularly. Manuscripts dealing with the structure and function of cell membranes, contractile systems, cellular organelles, and membrane channels, transporters, and pumps are encouraged. Studies dealing with integrated regulation of cellular function, including mechanisms of signal transduction, development, gene expression, cell-to-cell interactions, and the cell physiology of pathophysiological states, are also eagerly sought. Interdisciplinary studies that apply the approaches of biochemistry, biophysics, molecular biology, morphology, and immunology to the determination of new principles in cell physiology are especially welcome.
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