Cardiovascular changes during daily torpor in the laboratory mouse.
Cardiovascular changes during daily torpor in the laboratory mouse.
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DOI：
10.1152/ajpregu.00131.2009
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发表时间：
2009-09-01
期刊：
影响因子：
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通讯作者：
Gutilla, Margaret J
中科院分区：
文献类型：
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作者：
Swoap, Steven J;Gutilla, Margaret J
实验室老鼠是一种兼性的每日异温动物，因为它在热量限制下会经历几次麻木。小鼠是最常被研究的实验室哺乳动物，转基因小鼠经常被用来研究与减肥和热量摄入有关的许多生理功能。因此，在小鼠禁食引起的昏睡期间记录心血管变化的研究是必要的。在本研究中，C57BL/6小鼠被植入心电图/体温遥测仪或血压遥测仪。在禁食和暴露于19摄氏度的环境温度（T(a)）后，小鼠根据核心体温（T(b)）进入冬眠状态。在禁食期间，核心T(b)从36.6 +/- 0.2摄氏度降至最低25.9 +/- 0.9摄氏度，同时心率从每分钟607 +/- 12次（bpm）降至最低158 +/- 20次（bpm）。在核心T(b)为31℃以下，心率随T(b)呈指数下降，Q（10）为2.61 +/- 0.18。此外，植入血压遥测仪的小鼠表现出与植入心电图/体温遥测仪的小鼠相似的心率和活动特征，并且在进入麻木状态时心率和核心T(b)的下降与血压的下降是平行的。冬眠小鼠的最小收缩压、平均血压和舒张压分别为62.3 +/- 10.2、51.9 +/- 9.2、41.0 +/- 7.5 mmHg。在平均动脉压为75 - 100 mmHg时，冬眠小鼠的心率明显低于恒温小鼠（25-35%），表明总外周阻力在冬眠期间升高。这些数据为冬眠小鼠的心血管调节提供了新的和重要的见解。
The laboratory mouse is a facultative daily heterotherm in that it experiences bouts of torpor under caloric restriction. Mice are the most frequently studied laboratory mammal, and often, genetically modified mice are used to investigate many physiological functions related to weight loss and caloric intake. As such, research documenting the cardiovascular changes during fasting-induced torpor in mice is warranted. In the current study, C57BL/6 mice were implanted either with EKG/temperature telemeters or blood pressure telemeters. Upon fasting and exposure to an ambient temperature (T(a)) of 19 degrees C, mice entered torpor bouts as assessed by core body temperature (T(b)). Core T(b) fell from 36.6 +/- 0.2 degrees C to a minimum of 25.9 +/- 0.9 degrees C during the fast, with a concomitant fall in heart rate from 607 +/- 12 beats per minute (bpm) to a minimum of 158 +/- 20 bpm. Below a core T(b) of 31 degrees C, heart rate fell exponentially with T(b), and the Q(10) was 2.61 +/- 0.18. Further, mice implanted with blood pressure telemeters exhibited similar heart rate and activity profiles as those implanted with EKG/temperature telemeters, and the fall in heart rate and core T(b) during entrance into torpor was paralleled by a fall in blood pressure. The minimum systolic, mean, and diastolic blood pressures of torpid mice were 62.3 +/- 10.2, 51.9 +/- 9.2, 41.0 +/- 7.5 mmHg, respectively. Torpid mice had a significantly lower heart rate (25-35%) than when euthermic at mean arterial pressures from 75 to 100 mmHg, suggesting that total peripheral resistance is elevated during torpor. These data provide new and significant insight into the cardiovascular adjustments that occur in torpid mice.