目的　研究热暴露不同阶段对大鼠肝与心肌细胞热休克蛋白 70 (HSP70 )表达的影响 ,为探讨HSP70在细胞水平的表达机制 ,以及HSP70对热暴露机体的意义提供实验依据。方法　采用人工热气候室 [(34± 1)℃、湿度 6 0 % ],建立热暴露动物模型。SD大鼠 80只分为对照组和热暴露组 ,每组又分为 2、7、14、2 8d 4个时段。取肝与心肌组织做免疫组化SP法染色 ,应用图像分析系统分析组织HSP70含量的变化。结果　在热暴露的 4个时段 ,热暴露组肝 (灰度值分别为 137.0± 5 .1、137.0± 5 .2、137.8± 7.1、139.2± 5 .2 )与心肌 (灰度值分别为 15 6 .1± 4 .4、15 5 .1± 6 .2、15 5 .4± 4 .5、15 6 .2±5 .1)细胞的HSP70表达均明显强于对照组 ,差异有显著性 (P <0 .0 1或P <0 .0 5 ) ;适应时段对HSP70的表达强度无明显影响。热暴露 2d时HSP70在核内表达强于胞浆 ,肝枯否氏细胞HSP70阳性表达率明显高于对照组 ,差异有显著性 (P <0 .0 5 ) ;热暴露 2d与 2 8d时血清中肝与心肌细胞胞内酶浓度明显增高。结论　受热早期机体的重要器官会产生损伤性改变 ;HSP70高表达可作为组织细胞受损伤的标志 ;延长受热时间 ,机体产生热暴露 ,HSP70的高表达在此期热暴露的产生中起到重要作用 ;过长时间受热 ,机体将失去对热的适应 ,HSP7 Objective To study the effects of heat exposure on the expression of heat shock protein 70 (HSP70) in rat liver and myocardial cells in order to explore the mechanism of HSP70 expression at the cellular level and to provide experimental evidence for the significance of HSP70 on heat exposed rats. Methods The animal model of heat exposure was established by artificial hot climatic chamber [(34 ± 1) ℃, humidity 60%]. 80 SD rats were divided into control group and heat exposure group, each group was divided into 2,7,14,2 8d 4 time periods. Liver and myocardial tissue were harvested for immunohistochemical staining. The changes of HSP70 in tissues were analyzed by image analysis system. Results During the four heat exposure periods, the liver of the heat exposure group (gray value of 137.0 ± 5.1,137.0 ± 5.2,137.8 ± 7.1,139.2 ± 5.2 respectively) and the myocardium (gray value of 15 6 .1 ± 4 .4,155 .1 ± 6 .2,155 .4 ± 4 .5,156 .2 ± 5 .1) cells were significantly higher than the control group, the difference was significant (P <0.01 or P <0.05). The adaptation period had no significant effect on the expression of HSP70. The expression of HSP70 in nucleus was stronger than that in the cytoplasm at 2 days after heat exposure, and the positive rate of HSP70 in hepatic cells was significantly higher than that in the control group (P <0.05) Enzyme concentrations in liver and cardiomyocytes were significantly increased. CONCLUSIONS: Important organs in the early stage of heat exposure may produce damaging changes. High expression of HSP70 may be used as a marker of damaged tissue cells. Extending the duration of heat exposure and heat exposure in the body, the high expression of HSP70 plays an important role in the heat exposure during this period ; Prolonged exposure to heat, the body will lose its heat adaptation, HSP7