Deuster P A, Morrison S D, Ahrens R A
Med Sci Sports Exerc. 1985 Jun;17(3):385-92.
Food intakes, body composition, skeletal muscle mass, muscle protein synthesis, and myofibrillar protein degradation were studied in normal, food-restricted (FR), and Walker 256 tumor-bearing (TB) male Sprague-Dawley rats which were exercised (E) or maintained in a sedentary state. Exercise was enforced 3 times per wk for 100 min X session-1 at 20 m X min-1 on a 13% incline for 7 wk. Tumors were transplanted 3 wk after beginning the exercise program and were allowed to grow for 29 d. Food restriction was initiated during the last 2 wk of tumor growth. Food intakes and body lipid stores were reduced in all E groups, whereas body nitrogen was reduced only in the TBS animals. All E animals had significantly higher gastrocnemius muscle/body weight ratios than their sedentary counterparts, with the greatest ratio noted for the TBE animals. Muscle protein synthesis, measured by incorporation of [3H]tyrosine into gastrocnemius muscle, was significantly depressed in both FR and TB animals. Muscle protein breakdown, estimated by urinary 3-methylhistidine excretion, was significantly elevated in TB animals and slightly increased in FR animals. The results suggest that tumor presence significantly alters protein turnover to a greater extent than elicited by food restriction alone. Additionally, although exercise may have initially protected the animal by retarding tumor growth and muscle mass depletion, in the end, the energy costs of exercise accelerated the catabolic state.
对正常、食物限制（FR）以及荷Walker 256肿瘤（TB）的雄性Sprague-Dawley大鼠进行了食物摄入量、身体成分、骨骼肌质量、肌肉蛋白质合成和肌原纤维蛋白降解的研究，这些大鼠进行了运动（E）或处于久坐状态。每周进行3次运动，每次100分钟，速度为20米/分钟，坡度为13%，持续7周。在运动计划开始3周后移植肿瘤，让其生长29天。在肿瘤生长的最后2周开始食物限制。所有运动组的食物摄入量和身体脂质储备均减少，而仅荷瘤久坐组动物的身体氮减少。所有运动组动物的腓肠肌/体重比均显著高于久坐组，其中荷瘤运动组动物的该比例最高。通过将[3H]酪氨酸掺入腓肠肌来测量，肌肉蛋白质合成在食物限制组和荷瘤组动物中均显著降低。通过尿3-甲基组氨酸排泄量估算，肌肉蛋白质分解在荷瘤组动物中显著升高，在食物限制组动物中略有增加。结果表明，肿瘤的存在比单独的食物限制更能显著改变蛋白质周转。此外，尽管运动最初可能通过延缓肿瘤生长和肌肉质量消耗来保护动物，但最终，运动的能量消耗加速了分解代谢状态。
