Biology Department, University of Wisconsin-La Crosse, La Crosse, Wisconsin 54601, USA.
Am J Physiol Regul Integr Comp Physiol. 2012 May 15;302(10):R1202-8. doi: 10.1152/ajpregu.00018.2012. Epub 2012 Apr 4.
Hibernating mammals have developed many physiological adaptations to extreme environments. During hibernation, 13-lined ground squirrels (Ictidomys tridecemlineatus) must suppress hemostasis to survive prolonged body temperatures of 4-8°C and 3-5 heartbeats per minute without forming lethal clots. Upon arousal in the spring, these ground squirrels must be able to quickly restore normal clotting activity to avoid bleeding. Here we show that ground squirrel platelets stored in vivo at 4-8°C were released back into the blood within 2 h of arousal in the spring with a body temperature of 37°C but were not rapidly cleared from circulation. These released platelets were capable of forming stable clots and remained in circulation for at least 2 days before newly synthesized platelets were detected. Transfusion of autologous platelets stored at 4°C or 37°C showed the same clearance rates in ground squirrels, whereas rat platelets stored in the cold had a 140-fold increase in clearance rate. Our results demonstrate that ground squirrel platelets appear to be resistant to the platelet cold storage lesions observed in other mammals, allowing prolonged storage in cold stasis and preventing rapid clearance upon spring arousal. Elucidating these adaptations could lead to the development of methods to store human platelets in the cold, extending their shelf life.
冬眠哺乳动物已经发展出许多生理适应来应对极端环境。在冬眠期间，13 条纹地松鼠（Ictidomys tridecemlineatus）必须抑制止血作用，才能在长达数小时的 4-8°C 体温和 3-5 次心跳/min 的情况下存活，而不会形成致命的血栓。在春季苏醒时，这些地松鼠必须能够迅速恢复正常的凝血活性，以避免出血。在这里，我们发现，当地松鼠在春季以 37°C 的体温从 4-8°C 的体内储存中苏醒时，储存的血小板在 2 小时内重新回到血液中，但不会迅速从循环中清除。这些释放的血小板能够形成稳定的血栓，并在循环中至少存在 2 天，然后才检测到新合成的血小板。在 4°C 或 37°C 下储存的自体血小板的输血显示出在地松鼠中相同的清除率，而在冷储存中储存的大鼠血小板的清除率则增加了 140 倍。我们的结果表明，地松鼠的血小板似乎对其他哺乳动物中观察到的血小板冷储存损伤具有抗性，从而允许在冷停滞后长时间储存，并防止在春季苏醒时迅速清除。阐明这些适应机制可能会导致开发出在低温下储存人类血小板的方法，从而延长其保质期。
