Matthew C B
US Army Research Institute of Environmental Medicine, Natick, Massachusetts 01760-5007, USA.
Ann N Y Acad Sci. 1997 Mar 15;813:233-8. doi: 10.1111/j.1749-6632.1997.tb51700.x.
Repeated exposure to heat stress results in physiological adaptations which increase tolerance to heat stress. Core temperature (Tc) and heart rate (HR), two indices of successful heat acclimation, are both increased by the handling and restraint usually required to measure these variables in the rat. This study compares measurement of these variables in telemetry- and nontelemetry-equipped heat-acclimated rats. Four groups of male Sprague-Dawley rats were used: CAC (24, control for acclimated), HAC (24, heat acclimated), TCAC (3, telemetry implanted control for acclimation), and THAC (3, telemetry implanted, heat acclimated). The CAC and TCAC rats were maintained at 26 degrees C for 2 weeks; HAC and THAC groups were maintained at 32-33 degrees C for 2 weeks. The telemetry rats were surgically implanted with transmitters which measured activity, temperature, blood pressure (BP), and ECG. Following acclimation, the rats were subjected to a heat-stress test as follows: animals were placed in a chamber maintained at 41.5 degrees C until a Tc of 41.5 degrees C was reached, when the animals were removed to a 26 degrees C chamber to recover. The Tc of the CAC and HAC rats was manually measured with a rectal probe every 15 min. The TCAC and THAC rats had Tc, HR, and BP monitored electronically every 2.5 min from 30 min prior to heat stress through 30 min after heat. The THAC rats maintained lower Tc, HR, and BP than the TCAC rats throughout the heat stress. The CAC and HAC rats had higher Tc and slower rates of cooling after heat than either of the telemetry groups. Simultaneous measurement of HR, BP, and Tc has not previously been reported in unrestrained heat-acclimated rats. Measurement of these variables without the confounding effects of restraint or handling has increased the validity of the rat as a model for human heat acclimation.
反复暴露于热应激会导致生理适应，从而提高对热应激的耐受性。核心体温（Tc）和心率（HR）是热适应成功的两个指标，在大鼠中测量这些变量通常需要进行处理和束缚，这两者都会使它们升高。本研究比较了配备遥测设备和未配备遥测设备的热适应大鼠中这些变量的测量情况。使用了四组雄性斯普拉格-道利大鼠：CAC组（24只，热适应对照组）、HAC组（24只，热适应组）、TCAC组（3只，植入遥测设备的热适应对照组）和THAC组（3只，植入遥测设备，热适应组）。CAC组和TCAC组大鼠在26摄氏度下饲养2周；HAC组和THAC组在32 - 33摄氏度下饲养2周。给植入遥测设备的大鼠手术植入能测量活动、体温、血压（BP）和心电图的发射器。适应环境后，对大鼠进行如下热应激测试：将动物置于温度保持在41.5摄氏度的实验箱中，直到核心体温达到41.5摄氏度，此时将动物转移到26摄氏度的实验箱中恢复。每15分钟用直肠探头手动测量CAC组和HAC组大鼠的核心体温。从热应激前30分钟到热应激后30分钟，每2.5分钟对TCAC组和THAC组大鼠的核心体温、心率和血压进行电子监测。在整个热应激过程中，THAC组大鼠的核心体温、心率和血压均低于TCAC组大鼠。热应激后，CAC组和HAC组大鼠的核心体温较高，降温速度较慢，均高于任何一组植入遥测设备的大鼠。此前尚未有关于无束缚热适应大鼠同时测量心率、血压和核心体温的报道。在没有束缚或处理的混杂影响下测量这些变量，提高了大鼠作为人类热适应模型的有效性。
