Brown Justin W, Whitehurst Marvin E, Gordon Christopher J, Carroll Robert G
Department of Physiology, Brody School of Medicine, East Carolina University, 600 Moye Boulevard, Greenville, NC 27834, USA.
Shock. 2005 Mar;23(3):239-42.
Hemorrhage in rats causes a drop in body core temperature that is proportional to the hemorrhage volume. We tested the hypothesis that the hemorrhagic hypothermia is due to a downward shift in the thermoregulatory set point. If so, rats subjected to hemorrhage would prefer a cooler ambient temperature to enhance heat loss during the posthemorrhage period. Male Sprague-Dawley rats were fitted with carotid arterial catheters and biotelemetry temperature probes. Two days later, rats were placed in a temperature gradient chamber that allowed the rat to move between ambient temperatures of 15 degrees C to 40 degrees C. Rat location within the gradient was recorded as the selected ambient temperature. After 48 h, a 24 mL/kg hemorrhage was induced via the carotid cannula followed by a 24-h recovery period in the gradient. Body core and selected ambient temperatures significantly decreased after hemorrhage. Within 50 min, selected ambient temperature decreased by 11 degrees C, and returned to normal 100 min after hemorrhage. Within 80 min after hemorrhage, core temperature decreased by 2.3 degrees C, and returned to normal by 8 h after hemorrhage. Expanded analysis of the first hour after hemorrhage showed that reduction in selected ambient temperature preceded the drop in body core temperature. Importantly, the decrease in selected ambient temperature persisted even during the peak decrease in body core temperature. These results indicate that a decrease in thermoregulatory set point contributes to the drop in body core temperature after hemorrhage.
大鼠出血会导致体核温度下降，且下降幅度与出血量成正比。我们检验了以下假设：出血性体温过低是由于体温调节设定点向下偏移所致。如果是这样，出血后的大鼠会偏好较低的环境温度，以在出血后阶段增强热量散失。雄性斯普拉格-道利大鼠安装了颈动脉导管和生物遥测温度探头。两天后，将大鼠置于温度梯度箱中，该箱子允许大鼠在15摄氏度至40摄氏度的环境温度之间移动。记录大鼠在温度梯度中的位置作为所选环境温度。48小时后，通过颈动脉插管诱导24毫升/千克的出血，随后在温度梯度箱中恢复24小时。出血后体核温度和所选环境温度显著下降。在50分钟内，所选环境温度下降了11摄氏度，并在出血后100分钟恢复正常。出血后80分钟内，核心温度下降了2.3摄氏度，并在出血后8小时恢复正常。对出血后第一小时的进一步分析表明，所选环境温度的降低先于体核温度的下降。重要的是，即使在体核温度下降的峰值期间，所选环境温度的降低仍持续存在。这些结果表明，体温调节设定点的降低导致出血后体核温度下降。
