Kling K B, Costanzo J P, Lee R E
Department of Zoology, Miami University, Oxford, OH 45056.
J Comp Physiol B. 1994;164(4):316-20. doi: 10.1007/BF00346449.
We investigated the restoration in peripheral nerve function and simple neurobehavioral reflexes in the freeze-tolerant wood frog (Rana sylvatica). Thirty-two specimens, allowed to freeze for 39 h and ultimately cooled to -2.2 degrees C, were sampled at various time intervals up to 60 h after thawing at 5 degrees C was initiated. The sciatic nerves of treated frogs were initially unresponsive to stimulation, but usually regained excitability within 5 h. Except for a slight reduction in nerve excitability, characteristics of the compound action potentials of treated frogs were indistinguishable from those of control frogs. Recovery times for the hindlimb retraction and righting reflexes were 8 h and 14 h, respectively. Concentrations of the cryoprotectant glucose increased 8.2-fold in the sciatic nerve and 10.5-fold in the underlying semimembranosis muscle of treated frogs, and remained elevated for at least 60 h after thawing was initiated. These organs lost 47.2% and 15.9%, respectively, of their water during freezing, but were rehydrated within 2 h of the onset of thawing. The accumulation of glucose and the withdrawal of tissue water apparently are cryoprotective responses which enable this species to survive freezing.
我们研究了耐冻林蛙（Rana sylvatica）外周神经功能和简单神经行为反射的恢复情况。32个样本被冷冻39小时，最终冷却至-2.2摄氏度，在5摄氏度开始解冻后的60小时内的不同时间间隔进行取样。处理过的青蛙的坐骨神经最初对刺激无反应，但通常在5小时内恢复兴奋性。除了神经兴奋性略有降低外，处理过的青蛙的复合动作电位特征与对照青蛙的无法区分。后肢回缩反射和翻正反射的恢复时间分别为8小时和14小时。处理过的青蛙的坐骨神经中冷冻保护剂葡萄糖的浓度增加了8.2倍，其下方的半膜肌中增加了10.5倍，并且在开始解冻后至少60小时内一直保持升高。这些器官在冷冻过程中分别损失了47.2%和15.9%的水分，但在解冻开始后的2小时内重新水化。葡萄糖的积累和组织水分的排出显然是冷冻保护反应，使该物种能够在冷冻中存活。
