Skinner Lisa A, Milsom William K
Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia V6T 1Z4, Canada.
Physiol Biochem Zool. 2004 Sep-Oct;77(5):847-63. doi: 10.1086/422227.
In this study, we examined the cardiorespiratory patterns of harbour seal pups under normoxic/normocarbic (air), hypoxic/normocarbic (15%, 12%, and 9% O2 in air), and normoxic/hypercarbic (2%, 4%, and 6% CO2 in air) conditions while awake and sleeping on land. Animals were chronically instrumented to record electroencephalogram (EEG), electromyogram (EMG), and electrocardiogram (EKG) signals, which, along with respiration (whole-body plethysmography) and oxygen consumption (VO2), were recorded from animals breathing each gas mixture for 2-4 h on separate days. Our results show that for animals breathing air, VO2 was not significantly lower during slow-wave sleep (SWS; 7.71 +/- 0.39 mL O2 min(-1) kg(-1); all measurements are mean +/- SEM) than during wakefulness (WAKE; 8.80 +/- 0.25 mL O2 min(-1) kg(-1)) and was unaffected by changes in respiratory drive. Although there was no significant fall in VO2 associated with a decrease in arousal state, breathing frequency (f(R)) did decrease (from 18.80 +/- 1.50 breaths min(-1) in WAKE to 10.40 +/- 0.49 breaths min(-1) in SWS), while the incidence of long apneas (>20 s) increased (12.76 +/- 4.06 apneas h(-1) in WAKE and 31.95 +/- 2.37 apneas h(-1) in SWS). Breathing was rarely seen during rapid eye movement (REM) sleep. Tachypnea was present at all levels of increased respiratory drive; however, hypoxia induced a dramatic bradycardia regardless of arousal state, while hypercarbia produced a tachycardia in SWS only. The hypoxic and hypercarbic chemosensitivities of harbour seal pups were similar to those of terrestrial mammals; however, unlike terrestrial mammals, where hypoxic and hypercarbic sensitivities are often reduced during SWS, the sensitivity of harbour seal pups to hypoxia and hypercarbia remained unchanged during the decrease in arousal state from WAKE to SWS.
在本研究中，我们检测了港海豹幼崽在常氧/常碳酸（空气）、低氧/常碳酸（空气中氧气含量为15%、12%和9%）以及常氧/高碳酸（空气中二氧化碳含量为2%、4%和6%）条件下，于陆地上清醒和睡眠时的心肺模式。对动物进行长期仪器植入以记录脑电图（EEG）、肌电图（EMG）和心电图（EKG）信号，这些信号连同呼吸（全身体积描记法）和耗氧量（VO2），在不同日期让动物呼吸每种气体混合物2 - 4小时期间进行记录。我们的结果表明，对于呼吸空气的动物，慢波睡眠（SWS；7.71±0.39 mL O2 min(-1) kg(-1)；所有测量值均为平均值±标准误）期间的VO2并不显著低于清醒状态（WAKE；8.80±0.25 mL O2 min(-1) kg(-1)），且不受呼吸驱动变化的影响。尽管VO2没有随着觉醒状态的降低而显著下降，但呼吸频率（f(R)）确实降低了（从清醒时的18.80±1.50次呼吸min(-1)降至慢波睡眠时的10.40±0.49次呼吸min(-1)），而长呼吸暂停（>20秒）的发生率增加了（清醒时为12.76±4.06次呼吸暂停h(-1)，慢波睡眠时为31.95±2.37次呼吸暂停h(-1)）。快速眼动（REM）睡眠期间很少见到呼吸。在所有呼吸驱动增加的水平下均出现呼吸急促；然而，无论觉醒状态如何，低氧都会引发显著的心动过缓，而高碳酸血症仅在慢波睡眠时会引发心动过速。港海豹幼崽的低氧和高碳酸化学敏感性与陆生哺乳动物相似；然而，与陆生哺乳动物不同，陆生哺乳动物在慢波睡眠期间低氧和高碳酸敏感性通常会降低，而港海豹幼崽从清醒到慢波睡眠觉醒状态降低期间，对低氧和高碳酸的敏感性保持不变。
