Haman François, Peronnet François, Kenny Glen P, Doucet Eric, Massicotte Denis, Lavoie Carole, Weber Jean-Michel
Biology Department, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5.
J Appl Physiol (1985). 2004 Jan;96(1):32-40. doi: 10.1152/japplphysiol.00427.2003. Epub 2003 Aug 29.
Carbohydrates (CHO) can play an important thermogenic role during shivering, but the effect of their availability on the use of other oxidative fuels is unclear. Using indirect calorimetry and tracer methods ([U-13C]glucose ingestion), we have determined the specific contributions of plasma glucose, muscle glycogen, proteins, and lipids to total heat production (Hprod) in men exposed to cold for 2-h (liquid-conditioned suit perfused with 10 degrees C water). Measurements were made after low-CHO diet and exercise (Lo) and high-CHO diet without exercise (Hi). The size of CHO reserves had no effect on Hprod but a major impact on fuel selection before and during shivering. In the cold, a complete shift from lipid oxidation for Lo (53, 28, and 19% Hprod for lipids, CHO, and proteins, respectively) to CHO-based metabolism for Hi (23, 65, and 12% Hprod for lipids, CHO, and proteins, respectively) was observed. Plasma glucose oxidation remains a minor fuel under all conditions (<13% Hprod), falling to 7% Hprod for Lo. Therefore, adjusting plasma glucose oxidation to compensate for changes in muscle glycogen oxidation is not a strategy used for maintaining heat production. Instead, proteins and lipids share responsibility for this compensation. We conclude that humans can show remarkable flexibility in oxidative fuel selection to ensure that heat production is not compromised during sustained cold exposure.
碳水化合物（CHO）在寒颤过程中可发挥重要的产热作用，但其可利用性对其他氧化燃料利用的影响尚不清楚。我们采用间接测热法和示踪方法（摄入[U-13C]葡萄糖），测定了暴露于寒冷环境2小时（穿着灌注10℃水的液体调节服）的男性中，血浆葡萄糖、肌肉糖原、蛋白质和脂质对总产热（Hprod）的具体贡献。测量分别在低CHO饮食和运动后（Lo）以及高CHO饮食且不运动后（Hi）进行。CHO储备量对Hprod没有影响，但对寒颤前和寒颤期间的燃料选择有重大影响。在寒冷环境中，观察到从Lo组以脂质氧化为主（脂质、CHO和蛋白质分别占Hprod的53%、28%和19%）完全转变为Hi组以CHO为基础的代谢方式（脂质、CHO和蛋白质分别占Hprod的23%、65%和12%）。在所有条件下，血浆葡萄糖氧化仍然是次要燃料（<13%Hprod），Lo组降至7%Hprod。因此，调整血浆葡萄糖氧化以补偿肌肉糖原氧化的变化并不是维持产热的策略。相反，蛋白质和脂质共同承担这种补偿作用。我们得出结论，人类在氧化燃料选择上具有显著的灵活性，以确保在持续寒冷暴露期间产热不受影响。
