Raue Ulrika, Slivka Dustin, Jemiolo Bozena, Hollon Chris, Trappe Scott
Human Performance Laboratory Ball State University, Muncie, Indiana 47306, USA.
J Appl Physiol (1985). 2006 Jul;101(1):53-9. doi: 10.1152/japplphysiol.01616.2005. Epub 2006 Apr 6.
The purpose of this study was to investigate mRNA expression of several key skeletal muscle myogenic controllers; myogenic differentiation factor (MyoD), muscle regulatory factor 4 (MRF4), myogenic factor 5 (Myf5), myogenin, myostatin, and myocyte enhancer factor 2 (MEF2) at rest and 4 h after a single bout of resistance exercise (RE) in young and old women. Eight young women (YW; 23 +/- 2 yr, 67 +/- 5 kg) and six old women (OW; 85 +/- 1 yr, 67 +/- 4 kg) performed 3 sets of 10 repetitions of bilateral knee extensions at 70% of one repetition maximum. Muscle biopsies were taken from the vastus lateralis before and 4 h after RE. Using real-time RT PCR, mRNA from the muscle samples was amplified and normalized to GAPDH. At rest, OW expressed higher (P < 0.05) levels of MyoD, MRF4, Myf5, myogenin, and myostatin compared with YW. In response to RE, there was a main time effect (P < 0.05) for the YW and OW combined in the upregulation of MyoD (2.0-fold) and MRF4 (1.4-fold) and in the downregulation of myostatin (2.2-fold). There was a trend (P = 0.08) for time x age interaction in MRF4. These data show that old women express higher myogenic mRNA levels at rest. The higher resting myogenic mRNA levels in old women may reflect an attempt to preserve muscle mass and function. When challenged with RE, old women appear to respond in a similar manner as young women.
本研究旨在调查年轻和老年女性在单次抗阻运动（RE）前静息状态及运动后4小时，几种关键骨骼肌生肌调控因子的mRNA表达情况，这些调控因子包括生肌分化因子（MyoD）、肌肉调节因子4（MRF4）、生肌因子5（Myf5）、肌细胞生成素、肌肉生长抑制素和肌细胞增强因子2（MEF2）。八名年轻女性（YW；23±2岁，67±5千克）和六名老年女性（OW；85±1岁，67±4千克）以1次最大重复量的70%进行3组每组10次的双侧膝关节伸展运动。在RE前及运动后4小时从股外侧肌取肌肉活检样本。使用实时逆转录聚合酶链反应（RT PCR），对肌肉样本中的mRNA进行扩增并以甘油醛-3-磷酸脱氢酶（GAPDH）进行标准化。静息状态下，与YW相比，OW的MyoD、MRF4、Myf5、肌细胞生成素和肌肉生长抑制素表达水平更高（P<0.05）。在RE刺激下，YW和OW合并组在MyoD上调（2.0倍）和MRF4上调（1.4倍）以及肌肉生长抑制素下调（2.2倍）方面存在主要的时间效应（P<0.05）。MRF4存在时间×年龄交互作用的趋势（P=0.08）。这些数据表明老年女性在静息状态下生肌mRNA水平更高。老年女性静息状态下较高的生肌mRNA水平可能反映了其维持肌肉质量和功能的一种尝试。当受到RE刺激时，老年女性的反应似乎与年轻女性相似。
