Bhowmick Saurav, Drew Kelly L
Laboratory of CNS Injury and Repair, JFK Neuroscience Institute, Hackensack Meridian Health JFK Medical Center, 65 James St., Edison, NJ 08820, USA.
Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, USA; Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA.
Cond Med. 2019 Jun;2(3):134-141.
Hibernating mammals exhibit an innate physiological ability to withstand dramatic fluctuations in blood flow that occurs during hibernation and arousal or experimental models of ischemia reperfusion without significant damage. These innate adaptations are of significance particularly to organs that are highly susceptible to energy deprivation, such as the brain and the heart. Among vertebrates, the arctic ground squirrel (AGS) is a species that tolerates ischemic/anoxic insult. During the process of entering hibernation, a state of prolonged torpor, the AGS undergoes a profound decrease in respiratory rate, heart rate, blood flow, cerebral perfusion, and body temperature (Tb). The reduced level of blood flow during torpor resembles an ischemic state, albeit without energy deficit. During the process of arousal or emergence from torpor, however, when Tb, respiratory rate, heart rate, and blood flow rapidly returns to pre-torpid levels, the rapid return of cerebral blood flow mimics aspects of reperfusion such as is seen after stroke or cardiac arrest. This sublethal ischemic/reperfusion insult experienced by AGS during the process of arousal may precondition AGS to tolerate otherwise lethal ischemic/reperfusion injury induced in the laboratory. In this review, we will summarize some of the mechanisms implemented by mammalian hibernators to combat ischemia/anoxia tolerance.
冬眠的哺乳动物表现出一种与生俱来的生理能力，能够承受在冬眠、觉醒过程中或缺血再灌注实验模型中发生的血流剧烈波动，而不会受到显著损伤。这些先天适应性对那些极易受到能量剥夺影响的器官，如大脑和心脏，尤为重要。在脊椎动物中，北极地松鼠（AGS）是一种能够耐受缺血/缺氧损伤的物种。在进入长时间蛰伏状态即冬眠的过程中，北极地松鼠的呼吸频率、心率、血流、脑灌注和体温（Tb）都会大幅下降。蛰伏期间血流水平的降低类似于缺血状态，尽管没有能量不足。然而，在从蛰伏状态觉醒或苏醒的过程中，当体温、呼吸频率、心率和血流迅速恢复到蛰伏前水平时，脑血流的快速恢复模拟了再灌注的某些方面，如中风或心脏骤停后所见。北极地松鼠在觉醒过程中经历的这种亚致死性缺血/再灌注损伤可能使它对实验室诱导的其他致死性缺血/再灌注损伤产生耐受性。在这篇综述中，我们将总结哺乳动物冬眠者为对抗缺血/缺氧耐受性而采用的一些机制。
