Meir Jessica U, Ponganis Paul J
Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093-0204, USA.
Physiol Biochem Zool. 2010 May-Jun;83(3):531-40. doi: 10.1086/651070.
Hypothermia-induced reductions in metabolic rate have been proposed to suppress metabolism and prolong the duration of aerobic metabolism during dives of marine mammals and birds. To determine whether core hypothermia might contribute to the repetitive long-duration dives of the northern elephant seal Mirounga angustirostris, blood temperature profiles were obtained in translocated juvenile elephant seals equipped with a thermistor and backpack recorder. Representative temperature (the y-intercept of the mean temperature vs. dive duration relationship) was 37.2 degrees C +/- 0.6 degrees C (n=3 seals) in the extradural vein, 38.1 degrees C +/- 0.7 degrees C (n = 4 seals) in the hepatic sinus, and 38.8 degrees +/- 1.6 degrees C (n = 6 deals) in the aorta. Mean temperature was significantly though weakly negatively related to dive duration in all but one seal. Mean venous temperatures of all dives of individual seals ranged between 36 degrees and 38 degrees C, while mean arterial temperatures ranged between 35 degrees and 39 degrees C. Transient decreases in venous and arterial temperatures to as low as 30 degrees -33 degrees C occurred in some dives >30 min (0.1% of dives in the study). The lack of significant core hypothermia during routine dives (10-30 min) and only a weak negative correlation of mean temperature with dive duration do not support the hypothesis that a cold-induced Q(10) effect contributes to metabolic suppression of central tissues during dives. The wide range of arterial temperatures while diving and the transient declines in temperature during long dives suggest that alterations in blood flow patterns and peripheral heat loss contribute to thermoregulation during diving.
体温过低引起的代谢率降低被认为可以抑制新陈代谢，并延长海洋哺乳动物和鸟类潜水时有氧代谢的持续时间。为了确定核心体温过低是否可能有助于北象海豹（Mirounga angustirostris）进行重复性的长时间潜水，研究人员在配备了热敏电阻和背包记录仪的易地幼象海豹身上获取了体温曲线。硬膜外静脉的代表性温度（平均温度与潜水持续时间关系的y轴截距）为37.2摄氏度±0.6摄氏度（n = 3头海豹），肝窦为38.1摄氏度±0.7摄氏度（n = 4头海豹），主动脉为38.8摄氏度±1.6摄氏度（n = 6头海豹）。除了一头海豹外，所有海豹的平均温度与潜水持续时间均呈显著但微弱的负相关。个体海豹所有潜水的平均静脉温度在36摄氏度至38摄氏度之间，而平均动脉温度在35摄氏度至39摄氏度之间。在一些时长超过30分钟的潜水中（占本研究潜水次数的0.1%），静脉和动脉温度会短暂降至30摄氏度至33摄氏度。在常规潜水（10 - 30分钟）期间缺乏显著的核心体温过低现象，且平均温度与潜水持续时间仅有微弱的负相关，这并不支持寒冷诱导的Q10效应有助于潜水期间中央组织代谢抑制的假说。潜水时动脉温度范围广泛以及长时间潜水期间温度的短暂下降表明，血流模式的改变和外周热量损失有助于潜水期间的体温调节。
