Wang L C
J Appl Physiol Respir Environ Exerc Physiol. 1980 Dec;49(6):975-8. doi: 10.1152/jappl.1980.49.6.975.
The present study investigated the availability of substrates as a limiting factor in acute cold exposure. By use of a self-control experimental design, thermogenesis was measured in rats at -10 degrees C under 21% O2-79% He following different feeding regimes. Overnight fasting resulted in the lowest total heat production (9,949 +/- 189 cal/120 min, mean +/- SE, n = 11), maximum rate of thermogenesis (1,320 +/- 23 cal/15 min), and final body temperature (31.0 +/- 0.3 degrees C). The values were significantly lower than those found after overnight rationing (10,630 +/- 231, 1,386 +/- 29, and 32.8 +/- 0.5, respectively) or ad libitum feeding (10,821 +/- 224, 1,395 +/- 27, and 33.5 +/- 0.3). Rats fasted overnight but fed intragastrically a 5-ml substrate mixture (3 kcal/ml) 60 min prior to cold exposure resulted in the highest values for all parameters (11,553 +/- 207, 1,488 +/- 23, and 33.7 +/- 0.4). The increases were not due to the specific dynamic action of food. Since the levels of maximum thermogenesis and cold tolerance can be modulated by feeding, it is evident that substrate availability limits thermogenesis in severe cold independent of respiratory-cardiovascular functions and cellular oxidative capabilities.
本研究调查了底物可用性作为急性冷暴露中的一个限制因素。通过采用自身对照实验设计，在-10℃、21% O₂ - 79% He条件下，对不同喂养方式的大鼠进行产热测量。过夜禁食导致总产热量最低（9,949 ± 189卡/120分钟，平均值±标准误，n = 11）、最大产热速率（1,320 ± 23卡/15分钟）和最终体温（31.0 ± 0.3℃）。这些值显著低于过夜定量喂食（分别为10,630 ± 231、1,386 ± 29和32.8 ± 0.5）或自由进食（10,821 ± 224、1,395 ± 27和33.5 ± 0.3）后的测量值。过夜禁食但在冷暴露前60分钟经胃内给予5毫升底物混合物（3千卡/毫升）的大鼠，所有参数的值最高（11,553 ± 207、1,488 ± 23和33.7 ± 0.4）。这些增加并非由于食物的特殊动力作用。由于最大产热水平和耐寒性可通过喂养进行调节，显然底物可用性在严寒中限制产热，且与呼吸 - 心血管功能和细胞氧化能力无关。
