Naito H, Powers S K, Demirel H A, Sugiura T, Dodd S L, Aoki J
Department of Exercise Physiology, School of Health and Sports Science, Juntendo University, Inba, Chiba 113-003, Japan.
J Appl Physiol (1985). 2000 Jan;88(1):359-63. doi: 10.1152/jappl.2000.88.1.359.
This study tested the hypothesis that elevation of heat stress proteins by whole body hyperthermia is associated with a decrease in skeletal muscle atrophy induced by reduced contractile activity (i.e. , hindlimb unweighting). Female adult rats (6 mo old) were assigned to one of four experimental groups (n = 10/group): 1) sedentary control (Con), 2) heat stress (Heat), 3) hindlimb unweighting (HLU), or 4) heat stress before hindlimb unweighting (Heat+HLU). Animals in the Heat and Heat+HLU groups were exposed to 60 min of hyperthermia (colonic temperature approximately 41.6 degrees C). Six hours after heat stress, both the HLU and Heat+HLU groups were subjected to hindlimb unweighting for 8 days. After hindlimb unweighting, the animals were anesthetized, and the soleus muscles were removed, weighed, and analyzed for protein content and the relative levels of heat shock protein 72 (HSP72). Compared with control and HLU animals, the relative content of HSP72 in the soleus muscle was significantly elevated (P < 0.05) in both the Heat and Heat+HLU animals. Although hindlimb unweighting resulted in muscle atrophy in both the HLU and Heat+HLU animals, the loss of muscle weight and protein content was significantly less (P < 0.05) in the Heat+HLU animals. These data demonstrate that heat stress before hindlimb unweighting can reduce the rate of disuse muscle atrophy. We postulate that HSP70 and/or other stress proteins play a role in the control of muscle atrophy induced by reduced contractile activity.
全身热疗引起的热应激蛋白升高与收缩活动减少（即后肢去负荷）所致的骨骼肌萎缩减轻相关。成年雌性大鼠（6月龄）被分为四个实验组之一（每组n = 10）：1）静息对照组（Con），2）热应激组（Heat），3）后肢去负荷组（HLU），或4）后肢去负荷前热应激组（Heat+HLU）。Heat组和Heat+HLU组的动物接受60分钟的热疗（结肠温度约41.6摄氏度）。热应激6小时后，HLU组和Heat+HLU组均进行8天的后肢去负荷。后肢去负荷后，将动物麻醉，取出比目鱼肌，称重，并分析蛋白质含量和热休克蛋白72（HSP72）的相对水平。与对照组和HLU组动物相比，Heat组和Heat+HLU组动物比目鱼肌中HSP72的相对含量显著升高（P < 0.05）。虽然后肢去负荷导致HLU组和Heat+HLU组动物出现肌肉萎缩，但Heat+HLU组动物的肌肉重量和蛋白质含量损失显著较少（P < 0.05）。这些数据表明，后肢去负荷前的热应激可降低废用性肌肉萎缩的速率。我们推测HSP70和/或其他应激蛋白在控制收缩活动减少所致的肌肉萎缩中发挥作用。
