The rehabilitating effects of running exercise on the decreased skeletal muscle due to low protein diet.

研究了自愿跑步对低蛋白饮食所致大鼠肌肉萎缩的康复作用。将雌性断奶大鼠随机分为4组：安静对照组(SP/C)、运动组(SP/E)、安静对照组(LP/C)、运动组(LP/E)。大鼠被允许随意获得食物和水。运动大鼠从一开始就被放在钢笼子里，没有跑轮。7周龄LP组用低蛋白饲料替代SP饲料。3周后取腓肠肌、比目鱼肌(SOL)、指长伸肌(EDL)解剖称重。硝酸处理后，解剖显微镜下投影仪计数肌纤维数。用图像处理系统测量纤维面积。在10.8、4.5和4.3℃预孵化后，用肌球蛋白ATPase法测定纤维组成(I型、IIA型、IIB型)。低蛋白质摄入量，在…中产生体重下降越多，心脏和骨骼肌的体重就会显著下降。虽然LP/E组的跑步活动量降至SP/E组的1/3~1/2，但运动仍能显著增加肌肉重量，对骨骼肌重的恢复有效。蛋白质缺乏使肌肉重量下降，主要是由于肌纤维数量和大小的减少，尤其是I型。然而，运动抑制了纤维大小和数量的减少，肌肉重量恢复到对照水平。纤维数量和大小的恢复在很大程度上是由于I型肌纤维的恢复，因此，I型SOL主要对低蛋白质摄入量和运动做出反应，而不是以II型EDL为主。因此，跑步运动可以抑制低蛋白质摄入量时肌纤维数量和面积的减少，肌肉可以恢复正常。这些结果提示，运动可能是巴布亚新几内亚高原居民对蛋白质缺乏适应机制的重要因素，尽管他们的身体很强壮，但蛋白质摄入量很低。较少

The rehabilitating effects of voluntary running on muscle atrophy due to a low protein diet were studied in rat muscle. Female weanling rats were randomly assigned to four experimental gouts : sedentary control on standard protein diet(SP/C), exercising on SP diet(SP/E), sedentary control on low protein diet (LP/C), exercising on LP diet(LP/E). Rats were allowed ad libitum access food and water. Exercising rats were placed in steel cages free access to running wheels from the beginning. Low protein diet replaced SP diet in LP groups on 7 weeks of age. Three weeks later, gastrocnemius, soleus(SOL), extensor digitorum longus(EDL) muscles were dissected and weighed. Fiber number of muscle was counted through profile projector under a dissecting microscope after nitric acid treatment. Fiber area was measured by an image processing system. Fiber composition (typesI, IIA, IIB) was determined with the myosin ATPase method after pre incubation at 10.8, 4.5, and 4.3.Low protein intake, producin … More g a loss of body-weight, caused a significant weight loss of heart and skeletal muscles. Although running activity of LP/E group was lowered to 1/3-1/2 of that of SP/E group, exercise still increased muscle weights significantly and was effective in recovery of weight of skeletal muscles. Protein deficiency reduced the muscle weight due to the decrease of number and size in muscle fibers, especially in type 1. However, the reductions of fiber size and number were inhibited by exercise and the muscle weight was restored to control level. The recovery of fiber number and size was largely due to that of type I.Thus, predominantly type I SOL responded to low protein intake and exercise rather than predominantly type II EDL.It was concluded that the decrease in number and area of muscle fibers during low protein intake was inhibited by running exercise and the muscle can be restored to normal. These results suggested that exercise may be an essential factor for adaptive mechanism to protein deficiency in Papua New Guinea highlanders, whose physique was very muscular in spite of low protein intake. Less