Kregel K C, Moseley P L, Skidmore R, Gutierrez J A, Guerriero V
Department of Exercise Science, University of Iowa, Iowa City 52242, USA.
J Appl Physiol (1985). 1995 Nov;79(5):1673-8. doi: 10.1152/jappl.1995.79.5.1673.
To determine whether aging results in reduced accumulation of the 70-kDa heat shock protein (HSP70) in response to a thermal challenge, experiments were conducted in conscious and freely moving mature (12-mo-old) and senescent (24-mo-old) male Fischer 344 rats. Rats were assigned to a euthermic control group or a nonexertionally heated group that was exposed to an ambient temperature of 42 degrees C until colonic temperature reached 41 degrees C. Samples were subsequently obtained from the liver and myocardium, and absolute levels of both the constitutive and inducible forms of HSP70 were quantitated. Heat-stressed rats had significantly elevated HSP70 levels in the liver compared with the euthermic groups. Post hoc comparisons revealed that heat stress elicited marked elevations in liver HSP70 in mature rats compared with age-matched control animals. In contrast, HSP70 values were unchanged in the senescent heated group vs. the control group. In the myocardium, heat stress produced marked increases in HSP70 levels in both the mature and senescent groups compared with age-matched control animals, with accumulation significantly blunted in the senescent vs. mature rats. Thus the increases in liver and myocardial HSP70 accumulation in response to nonexertional heat stress are attenuated with senescence. Because these proteins are postulated to protect cells from injury and enhance cellular recovery from heat stress, the data suggest that an aging organism has a reduced ability to properly maintain cellular function and integrity after a thermal challenge.
为了确定衰老是否会导致在热刺激下70 kDa热休克蛋白（HSP70）的积累减少，我们对清醒且自由活动的成年（12月龄）和衰老（24月龄）雄性Fischer 344大鼠进行了实验。将大鼠分为正常体温对照组或非运动性加热组，非运动性加热组暴露于42℃的环境温度下，直到结肠温度达到41℃。随后从肝脏和心肌获取样本，并对组成型和诱导型HSP70的绝对水平进行定量。与正常体温组相比，热应激大鼠肝脏中的HSP70水平显著升高。事后比较显示，与年龄匹配的对照动物相比，热应激使成年大鼠肝脏中的HSP70显著升高。相比之下，衰老加热组与对照组的HSP70值没有变化。在心肌中，与年龄匹配的对照动物相比，热应激使成年组和衰老组的HSP70水平均显著增加，但衰老大鼠的积累明显低于成年大鼠。因此，衰老会减弱非运动性热应激引起的肝脏和心肌HSP70积累的增加。由于这些蛋白质被认为可以保护细胞免受损伤并增强细胞从热应激中恢复的能力，这些数据表明衰老的生物体在热刺激后维持细胞功能和完整性的能力降低。
