McGregor I S, Lee A M
Department of Psychology, University of Sydney, NSW, Australia.
Physiol Behav. 1995 Feb;57(2):277-86. doi: 10.1016/0031-9384(94)00221-p.
Indirect calorimetry was used to investigate whole-body metabolic changes occurring during and after feeding in the rat. Measurement of respiratory exchange allowed the derivation of respiratory quotient (RQ = CO2 produced/O2 consumed) and energy expenditure [EE = O2 consumed (364 + 113RQ)], giving an estimate of the energy substrate (fat, carbohydrate, or protein) being utilised and the total substrate oxidation occurring, respectively. Concurrent measurement of locomotor activity (ACT) allowed the changes in EE attributable to feeding (postprandial thermogenesis) to be generally dissociated from those attributable to activity. Experiment 1 examined alterations in RQ, EE, and ACT following brief (< 5 min) calorically matched meals of Froot Loops (86% carbohydrate), casein (protein), lard (fat) and lab chow (mixed macronutrient) and following the ingestion of 0.1% saccharin (which is calorically inert). Rapid (< 5 mins) and sustained increases in RQ occurred following Froot Loop and lab chow meals indicating increased utilization of carbohydrates as an energy substrate. Casein caused little change in RQ, while lard caused a drop in RQ approximately 30 min following ingestion, indicating increased fat utilization following absorption of the lard meal. Saccharin caused little change in RQ, suggesting that a sweet taste is not sufficient to alter substrate utilization. Increased EE was seen following the Froot Loops and lab chow meals in the absence of corresponding increases in ACT, suggesting a postprandial thermogenic effect of these meals. In Experiment 2, the metabolic changes accompanying a large (5 g) and small (0.5 g) Froot Loops meal were compared. The large meal resulting in a larger, more rapid and more sustained increase in RQ than the small meal. In addition, there was an increase in EE in the absence of corresponding increases in ACT following the large meal suggesting the presence of postprandial thermogenesis. It is concluded that both meal macronutrient content and meal size are important determinants of postprandial substrate utilization and thermogenesis in rats.
采用间接测热法研究大鼠进食期间及进食后发生的全身代谢变化。通过测量呼吸交换率可得出呼吸商（RQ = 产生的CO₂/消耗的O₂）和能量消耗[EE = 消耗的O₂(364 + 113RQ)]，分别估算出所利用的能量底物（脂肪、碳水化合物或蛋白质）以及发生的总底物氧化量。同时测量运动活动（ACT），可使进食引起的能量消耗变化（餐后产热）与活动引起的变化区分开来。实验1研究了在摄入热量匹配的小餐（<5分钟）的Froot Loops（86%碳水化合物）、酪蛋白（蛋白质）、猪油（脂肪）和实验室饲料（混合宏量营养素）以及摄入0.1%糖精（无热量）后，呼吸商、能量消耗和运动活动的变化。摄入Froot Loops和实验室饲料后，呼吸商迅速（<5分钟）且持续升高，表明碳水化合物作为能量底物的利用率增加。酪蛋白对呼吸商影响不大，而猪油摄入后约30分钟呼吸商下降，表明猪油餐吸收后脂肪利用率增加。糖精对呼吸商影响不大，表明甜味不足以改变底物利用。摄入Froot Loops和实验室饲料后，能量消耗增加，而运动活动没有相应增加，表明这些餐食具有餐后产热效应。在实验2中，比较了摄入大餐（5克）和小餐（0.5克）Froot Loops时伴随的代谢变化。大餐导致呼吸商的升高幅度更大、速度更快且更持久。此外，表示大餐后能量消耗增加，而运动活动没有相应增加，表明存在餐后产热现象。得出的结论是，餐食的宏量营养素含量和餐量都是大鼠餐后底物利用和产热的重要决定因素。
