NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, the Netherlands.
NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, the Netherlands.
Exp Gerontol. 2021 Jan;143:111161. doi: 10.1016/j.exger.2020.111161. Epub 2020 Nov 20.
Muscle fiber capillarization plays a fundamental role in the regulation of skeletal muscle mass maintenance. However, it remains unclear to what extent capillarization is related to various other skeletal muscle characteristics. In this study we determined whether muscle fiber capillarization is independently associated with measures of skeletal muscle mass, both on a whole-body and cellular level, and post-absorptive muscle protein synthesis rates in healthy older men.
Forty-six healthy older (70 ± 4 y) men participated in a trial during which basal muscle protein synthesis rates were assessed using stable isotope tracer methodology. Blood and muscle biopsy samples were collected to assess post-absorptive muscle protein synthesis rates over a 3-hour period. Immunohistochemistry was performed to determine various indices of muscle fiber capillarization, size, type distribution, and myonuclear content/domain size. Dual energy x-ray absorptiometry scans were performed to determine whole-body and appendicular lean tissue mass.
Capillary-to-fiber ratio (C/Fi) and perimeter exchange (CFPE) index correlated with whole-body lean tissue mass (r = 0.43, P < 0.01 and r = 0.25, P < 0.10, respectively), appendicular lean tissue mass (r = 0.52, P < 0.001 and r = 0.37, P < 0.05, respectively) as well as appendicular lean tissue mass divided by body mass index (r = 0.65, P < 0.001 and r = 0.62, P < 0.001, respectively). Muscle fiber size correlated with C/Fi (r = 0.45, P < 0.01), but not with CFPE index. No associations were observed between different indices of muscle fiber capillarization and post-absorptive muscle protein synthesis rates in healthy, older men.
The present study provides further evidence that muscle fiber capillarization may be a critical factor in the regulation of skeletal muscle maintenance in healthy older men.
肌纤维毛细血管化在调节骨骼肌质量维持方面起着至关重要的作用。然而，毛细血管化与各种其他骨骼肌特征的关系程度尚不清楚。在这项研究中，我们确定了肌肉纤维毛细血管化是否与健康老年人的全身和细胞水平的骨骼肌质量以及吸收后肌肉蛋白质合成率的测量值独立相关。
46 名健康的老年人（70±4 岁）参加了一项试验，在此期间使用稳定同位素示踪剂方法评估基础肌肉蛋白质合成率。采集血液和肌肉活检样本，以评估 3 小时期间的吸收后肌肉蛋白质合成率。进行免疫组织化学检测，以确定肌肉纤维毛细血管化、大小、类型分布和肌核含量/域大小的各种指数。使用双能 X 射线吸收法扫描来确定全身和四肢瘦组织质量。
毛细血管与纤维比（C/Fi）和周长交换（CFPE）指数与全身瘦组织质量（r=0.43，P<0.01 和 r=0.25，P<0.10）、四肢瘦组织质量（r=0.52，P<0.001 和 r=0.37，P<0.05）以及四肢瘦组织质量除以体重指数（r=0.65，P<0.001 和 r=0.62，P<0.001）呈正相关。肌肉纤维大小与 C/Fi 呈正相关（r=0.45，P<0.01），但与 CFPE 指数无关。在健康的老年人中，不同的肌纤维毛细血管化指数与吸收后肌肉蛋白质合成率之间没有观察到相关性。
本研究进一步证明，肌肉纤维毛细血管化可能是调节健康老年人骨骼肌维持的关键因素。
