Heldmaier G, Klingenspor M, Werneyer M, Lampi B J, Brooks S P, Storey K B
Department of Biology, Philipps-University, D-35032 Marburg, Germany.
Am J Physiol. 1999 May;276(5):E896-906. doi: 10.1152/ajpendo.1999.276.5.E896.
Djungarian hamsters (Phodopus sungorus) acclimated to a short photoperiod (8:16-h light-dark cycle) display spontaneous daily torpor with ad libitum food availability. The time course of body temperature (Tb), metabolic rate, respiratory quotient (RQ), and substrate and enzyme changes was measured during entrance into torpor and in deep torpor. RQ, blood glucose, and serum lipids are high during the first hours of torpor but then gradually decline, suggesting that glucose is the primary fuel during the first hours of torpor, with a gradual change to lipid utilization. No major changes in enzyme activities were observed during torpor except for inactivation of the pyruvate dehydrogenase (PDH) complex in liver, brown adipose tissue, and heart muscle. PDH inactivation closely correlates with the reduction of total metabolic rate, whereas in brain, kidney, diaphragm, and skeletal muscle, PDH activity was maintained at the initial level. These findings suggest inhibition of carbohydrate oxidation in heart, brown adipose tissue, and liver during entrance into daily torpor.
适应短光照周期（8:16小时明暗循环）的西伯利亚仓鼠（Phodopus sungorus）在食物供应充足的情况下会自发出现每日蛰伏现象。在进入蛰伏状态和深度蛰伏期间，测量了体温（Tb）、代谢率、呼吸商（RQ）以及底物和酶的变化过程。在蛰伏的最初几个小时内，RQ、血糖和血脂较高，但随后逐渐下降，这表明在蛰伏的最初几个小时内葡萄糖是主要燃料，随后逐渐转变为利用脂质。在蛰伏期间，除了肝脏、棕色脂肪组织和心肌中的丙酮酸脱氢酶（PDH）复合体失活外，未观察到酶活性的重大变化。PDH失活与总代谢率的降低密切相关，而在脑、肾、膈肌和骨骼肌中，PDH活性维持在初始水平。这些发现表明，在进入每日蛰伏状态时，心脏、棕色脂肪组织和肝脏中的碳水化合物氧化受到抑制。
