Shining new light on mammalian diving physiology using wearable near-infrared spectroscopy
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Investigation of marine mammal dive-by-dive blood distribution and oxygenation has been limited by a lack of non-invasive technology for use in freely diving animals. Here, we developed a non-invasive near-infrared spectroscopy (NIRS) device to measure relative changes in blood volume and haemoglobin oxygenation continuously in the blubber and brain of voluntarily diving harbour seals. Our results show that seals routinely exhibit preparatory peripheral vasoconstriction accompanied by increased cerebral blood volume approximately 15 s before submersion. These anticipatory adjustments confirm that blood redistribution in seals is under some degree of cognitive control that precedes the mammalian dive response. Seals also routinely increase cerebral oxygenation at a consistent time during each dive, despite a lack of access to ambient air. We suggest that this frequent and reproducible reoxygenation pattern, without access to ambient air, is underpinned by previously unrecognised changes in cerebral drainage. The ability to track blood volume and oxygenation in different tissues using NIRS will facilitate a more accurate understanding of physiological plasticity in diving animals in an increasingly disturbed and exploited environment.
McKnight , J C , Bennett , K , Bronkhorst , M , Russell , D JF , Balfour , S , Milne , R , Bivins , M , Moss , S E W , Colier , W , Hall , A J & Thompson , D 2019 , ' Shining new light on mammalian diving physiology using wearable near-infrared spectroscopy ' PLoS Biology , vol. 17 , no. 6 , e3000306 . https://doi.org/10.1371/journal.pbio.3000306
Copyright: © 2019 McKnight et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
DescriptionFunding: National Environmental Research Council National Capability funding to the Sea Mammal Research Unit (grant no. SMRU1001), Sea Mammal Research Unit Consulting (10 year anniversary award).
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