Gulve E A, Rodnick K J, Henriksen E J, Holloszy J O
Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110.
Mech Ageing Dev. 1993 Feb;67(1-2):187-200. doi: 10.1016/0047-6374(93)90122-8.
We examined the effects of voluntary exercise on glucose transporter concentration in skeletal muscle from young adult and old female Long-Evans rats. Rats had free access to voluntary running wheels beginning at 4 months of age or remained sedentary. Exercising rats ran approximately 7.5, 6.2, 5.6 and 5.3 km/day during their 6th, 8th, 9th and 10th month of age, respectively. During the 23rd, 24th and 25th month of age running distance averaged 3.0, 2.8 and 2.4 km/day, respectively. At 10 and 25 months of age, glucose transporter protein concentration was assessed in epitrochlearis and flexor digitorum brevis muscles with a polyclonal antibody directed against the GLUT4 transporter isoform. GLUT4 protein concentration was not altered by the aging process (i.e., comparing 10- and 25-month-old rats) in either muscle type. Wheel running increased GLUT4 protein concentration by 45% in epitrochlearis muscles of 10-month-old rats relative to age-matched sedentary controls. The training-induced adaptation in GLUT4 protein was no longer present at age 25 months, probably because the running distance had declined by 50%. In the flexor digitorum brevis, exercise did not alter GLUT4 concentration at either 10 or 25 months, presumably due to insufficient recruitment of this muscle during wheel running as assessed by measurement of citrate synthase and hexokinase enzyme activities. Wheel running induced cardiac and soleus muscle hypertrophy in 10- and 25-month-old rats. In summary, voluntary wheel running can induce an increase in skeletal muscle GLUT4 protein concentration in adult rats. Older rats that run less exhibit cardiac and soleus muscle hypertrophy, but do not maintain an elevated GLUT4 protein concentration in the epitrochlearis muscle. Aging does not alter GLUT4 protein concentration in the epitrochlearis or FDB muscles.
我们研究了自愿运动对年轻成年和老年雌性Long-Evans大鼠骨骼肌中葡萄糖转运蛋白浓度的影响。大鼠从4个月大开始可自由使用自愿跑步轮，或保持 sedentary 状态。运动大鼠在6、8、9和10月龄时每天分别跑约7.5、6.2、5.6和5.3公里。在23、24和25月龄时，跑步距离平均分别为每天3.0、2.8和2.4公里。在10和25月龄时，用针对GLUT4转运异构体的多克隆抗体评估肱三头肌和趾短屈肌中的葡萄糖转运蛋白浓度。在两种肌肉类型中，衰老过程（即比较10月龄和25月龄大鼠）均未改变GLUT4蛋白浓度。与年龄匹配的 sedentary 对照相比，自愿跑步使10月龄大鼠肱三头肌中的GLUT4蛋白浓度增加了45%。在25月龄时，训练诱导的GLUT4蛋白适应性变化不再存在，可能是因为跑步距离下降了50%。在趾短屈肌中，运动在10或25月龄时均未改变GLUT4浓度，推测是由于通过测量柠檬酸合酶和己糖激酶活性评估发现，在跑步过程中该肌肉募集不足。自愿跑步在10和25月龄大鼠中诱导了心脏和比目鱼肌肥大。总之，自愿跑步可诱导成年大鼠骨骼肌中GLUT4蛋白浓度增加。跑得较少的老年大鼠表现出心脏和比目鱼肌肥大，但肱三头肌中GLUT4蛋白浓度未维持升高。衰老不会改变肱三头肌或趾短屈肌中的GLUT4蛋白浓度。
