CNRS, UMR 7338 Biomechanics and Bioengineering, Université de Technologie de Compiègne, Sorbonne University, Compiègne, France.
Sorbonne Paris Cité, UFR Santé Médecine et Biologie Humaine, Université Paris 13, Bobigny, France.
Acta Physiol (Oxf). 2018 Sep;224(1):e13072. doi: 10.1111/apha.13072. Epub 2018 Apr 23.
The effects of dehydration on muscle performance in human are still contradictory, notably regarding muscle force. The effect of water deprivation (WD) on mechanical properties of skeletal muscle, and more precisely its impact on slow and fast muscles, remains largely unknown. The aim of this study was to determine for the first time whether WD leads to changes in contractile properties of skeletal muscle and whether these changes were muscle-type-specific.
Sixteen-week-old male rats were assigned to either a control group (C) with water or a 96-hour WD group. At the end of the period, twitch and tetanus properties, as well as biochemical and structural analysis, were performed on soleus (SOL) and extensor digitorum longus (EDL) muscles.
Absolute twitch (Pt) and tetanic (P ) tension were, respectively, 17% and 14% lower in EDL of WD rats as compared with C rats, whereas unexpected increases of 43% and 25% were observed in SOL. Tensions normalized with respect to muscle mass were not affected by WD in EDL, whereas they were increased by more than 40% in SOL. A 96-hour WD period leads to a decrease in fibre cross-sectional area and absolute myofibrillar content only in EDL.
It is hypothesized that differences in the results between slow and fast muscles may come from (i) a muscle-type-specific effect of WD on protein balance, EDL showing a greater myofibrillar protein breakdown and (ii) a greater sensitivity to osmolality changes induced by WD in EDL than in SOL.
脱水对人体肌肉性能的影响仍然存在争议，尤其是在肌肉力量方面。水剥夺（WD）对骨骼肌机械性能的影响，以及更具体地说，其对慢肌和快肌的影响，仍然知之甚少。本研究的目的是首次确定 WD 是否导致骨骼肌收缩性能发生变化，以及这些变化是否具有肌肉类型特异性。
将 16 周龄雄性大鼠分为对照组（C）和 96 小时 WD 组，分别给予水或水剥夺。在实验结束时，对比目鱼肌（SOL）和趾长伸肌（EDL）进行单收缩和强直收缩特性以及生化和结构分析。
与 C 组大鼠相比，EDL 大鼠的绝对单收缩（Pt）和强直（P ）张力分别降低了 17%和 14%，而 SOL 大鼠的张力却出人意料地增加了 43%和 25%。与肌肉质量相比，EDL 大鼠的张力不受 WD 影响，而 SOL 大鼠的张力增加了 40%以上。96 小时 WD 期仅导致 EDL 纤维横截面积和绝对肌原纤维含量下降。
我们假设，慢肌和快肌之间结果的差异可能来自于（i）WD 对蛋白质平衡的肌肉类型特异性影响，EDL 表现出更大的肌原纤维蛋白分解，以及（ii）EDL 对 WD 引起的渗透压变化比 SOL 更敏感。
