Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
Pflugers Arch. 2020 Feb;472(2):281-292. doi: 10.1007/s00424-020-02353-w. Epub 2020 Feb 5.
Muscle inactivity reduces muscle protein synthesis (MPS), whereas a subsequent period of rehabilitation resistance training (retraining) increases MPS. However, less is known regarding muscle protein breakdown (MPB) during such conditions. Furthermore, nonsteroidal anti-inflammatory drugs (NSAIDs) may have a dampening effect on MPB during periods of inactivity in older individuals. Thus, we measured the average MPB, by use of the deuterated water methodology, during an immobilization period and a subsequent retraining period in older individuals with and without NSAID treatment. Eighteen men (60-80 years: range) were randomly assigned to ibuprofen (1200 mg/d, Ibu) or placebo (Plc). One lower limb was immobilized in a cast for 2 weeks and retrained for 2 weeks, and 2 × 20 g of whey protein was ingested daily during both periods. Besides MPB, the protein expression of different muscle degradation signaling molecules was investigated. MPB was lower during immobilization compared to retraining (p < 0.01). NSAID treatment did not affect the MPB rate during immobilization or retraining (p > 0.05). The protein expression of muscle degradation signaling molecules changed during the study intervention but were unaffected by NSAID treatment. The finding that MPB was lower during immobilization than during retraining indicates that an increased MPB may play an important role in the muscle protein remodeling processes taking place within the initial retraining period. Moreover, NSAID treatment did not significantly influence the MPB rate during 2 weeks of lower limb immobilization or during 2 weeks of subsequent retraining in older individuals.
肌肉不活动会降低肌肉蛋白质合成（MPS），而随后进行的康复抗阻训练（再训练）会增加 MPS。然而，对于这种情况下的肌肉蛋白质分解（MPB）了解较少。此外，非甾体抗炎药（NSAIDs）在老年人不活动期间可能会对 MPB 产生抑制作用。因此，我们使用氘水法测量了老年人在固定期和随后的再训练期期间的平均 MPB，这些人接受了 NSAID 治疗或未接受 NSAID 治疗。18 名男性（60-80 岁：范围）被随机分配到布洛芬（1200mg/d，Ibu）或安慰剂（Plc）组。一条下肢用石膏固定 2 周，再训练 2 周，在此期间每天摄入 2×20g 乳清蛋白。除了 MPB，还研究了不同肌肉降解信号分子的蛋白质表达。与再训练相比，固定期间的 MPB 较低（p<0.01）。NSAID 治疗并不影响固定期或再训练期的 MPB 率（p>0.05）。研究干预期间肌肉降解信号分子的蛋白质表达发生了变化，但不受 NSAID 治疗的影响。与再训练相比，固定期间的 MPB 较低的发现表明，增加的 MPB 可能在最初再训练期间发生的肌肉蛋白质重塑过程中发挥重要作用。此外，NSAID 治疗并没有显著影响老年人下肢固定 2 周或随后再训练 2 周期间的 MPB 率。
