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

研究了自主跑步对低蛋白饮食引起的大鼠肌肉萎缩的恢复作用。雌性断奶大鼠随机分为四组实验痛风组：久坐对照组标准蛋白质饮食（SP/C）、运动对照组低蛋白质饮食（SP/E）、久坐对照组低蛋白质饮食（LP/C）、运动对照组低蛋白质饮食（LP/E）。老鼠被允许随意获取食物和水。运动大鼠从一开始就被放置在钢笼子里，可以自由使用跑步轮。7周龄时，LP组以低蛋白饲粮替代SP饲粮。3周后，解剖腓肠肌、比目鱼肌、指长伸肌并称重。硝酸处理后，在解剖显微镜下用投影仪计数肌肉纤维数。利用图像处理系统测量光纤面积。在10.8、4.5和4.3预孵育后，用肌球蛋白atp酶法测定纤维组成（i型、IIA型、IIB型）。蛋白质摄入量低，导致体重下降，导致心脏和骨骼肌的体重明显下降。虽然LP/E组的跑步活动降低到SP/E组的1/3 ~ 1/2，但运动仍能显著增加肌肉重量，有效恢复骨骼肌重量。由于肌肉纤维的数量和大小减少，蛋白质缺乏使肌肉重量降低，特别是在1型中。然而，运动抑制了纤维大小和数量的减少，肌肉重量恢复到控制水平。纤维数量和大小的恢复主要是由于I型的恢复。因此，主要是I型的SOL对低蛋白质摄入和运动有反应，而不是主要是II型的EDL。由此可见，低蛋白质摄入时肌纤维数量和面积的减少受到跑步运动的抑制，肌肉可以恢复正常。这些结果表明，运动可能是巴布亚新几内亚高地人对蛋白质缺乏的适应机制的重要因素，尽管他们的蛋白质摄入量很低，但他们的体格非常强壮。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