Department of Zoology, University of British Columbia, Vancouver, V6T 1Z4, Canada.
J Comp Physiol B. 2011 Apr;181(3):361-71. doi: 10.1007/s00360-010-0532-4. Epub 2010 Nov 18.
It is not known how the Pacific hagfish (Eptatretus stoutii) can survive extended periods of anoxia. The present study used two experimental approaches to examine energy use during and following anoxic exposure periods of different durations (6, 24 and 36 h). By measuring oxygen consumption prior to anoxic exposure, we detected a circadian rhythm, with hagfish being active during night and showing a minimum routine oxygen consumption (RMR) during the daytime. By measuring the excess post-anoxic oxygen consumption (EPAOC) after 6 and 24 h it was possible to mathematically account for RMR being maintained even though heme stores of oxygen would have been depleted by the animal's metabolism during the first hours of anoxia. However, EPAOC after 36 h of anoxia could not account for RMR being maintained. Measurements of tissue glycogen disappearance and lactate appearance during anoxia showed that the degree of glycolysis and the timing of its activation varied among tissues. Yet, neither measurement could account for the RMR being maintained during even the 6-h anoxic period. Therefore, two independent analyses of the metabolic responses of hagfish to anoxia exposure suggest that hagfish utilize metabolic rate suppression as part of the strategy for longer-term anoxia survival.
目前尚不清楚太平洋盲鳗（Eptatretus stoutii）如何能在长时间缺氧的情况下存活。本研究采用两种实验方法，研究了不同缺氧暴露时间（6、24 和 36 小时）期间和之后的能量利用情况。通过测量缺氧暴露前的耗氧量，我们检测到昼夜节律，盲鳗在夜间活动，白天的基础代谢率（RMR）最低。通过测量 6 小时和 24 小时后的缺氧后过量耗氧量（EPAOC），可以从数学上解释即使动物在缺氧的最初几个小时内通过新陈代谢耗尽了血红素储备，RMR 仍能维持的原因。然而，36 小时缺氧后的 EPAOC 并不能解释 RMR 是如何维持的。缺氧过程中组织糖原消失和乳酸出现的测量表明，糖酵解的程度及其激活时间在不同组织中有所不同。然而，这两种测量方法都不能解释即使在 6 小时的缺氧期内 RMR 是如何维持的。因此，对盲鳗缺氧暴露代谢反应的两种独立分析表明，盲鳗利用代谢率抑制作为其长期缺氧生存策略的一部分。
