| Selective brain cooling and its vascular basis in diving seals. | |
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MedLine Citation:
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PMID: 20639422 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Brain (T(brain)), intra-aorta (T(aorta)), latissimus dorsi muscle (T(m)) and rectal temperature (T(r)) were measured in harp (Pagophilus groenlandicus) and hooded (Cystophora cristata) seals during experimental dives in 4 degrees C water. The median brain cooling was about 1 degrees C during 15 min diving, but in some cases it was as much as 2.5 degrees C. Cooling rates were slow for the first couple of minutes, but increased significantly after about 5 min of diving. The onset of cooling sometimes occurred before the start of the dive, confirming that the cooling is under cortical control, like the rest of the diving responses. T(aorta) also fell significantly, and was always lower than T(brain), while T(m) was fairly stable during dives. Detailed studies of the vascular anatomy of front flippers revealed that brachial arterial blood can be routed either through flipper skin capillaries for nutritive purposes and return through sophisticated vascular heat exchangers to avoid heat loss to the environment, or, alternatively, through numerous arterio-venous shunts in the skin and return by way of large superficial veins, which then carry cold blood to the heart. In the latter situation the extent to which the brain is cooled is determined by the ratio of carotid to brachial arterial blood flow, and water temperature, and the cooling is selective in that only those organs that are circulated will be cooled. It is concluded that T(brain) is actively down-regulated during diving, sometimes by as much as 2.5 degrees C, whereby cerebral oxygen requirements may be reduced by as much as 25% during extended dives. |
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Authors:
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Arnoldus Schytte Blix; Lars Walløe; Edward B Messelt; Lars P Folkow |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The Journal of experimental biology Volume: 213 ISSN: 1477-9145 ISO Abbreviation: J. Exp. Biol. Publication Date: 2010 Aug |
Date Detail:
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Created Date: 2010-07-19 Completed Date: 2010-10-19 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0243705 Medline TA: J Exp Biol Country: England |
Other Details:
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Languages: eng Pagination: 2610-6 Citation Subset: IM |
Affiliation:
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Department of Arctic Biology, University of Tromsø, N-9037 Tromsø, Norway. asb000@uit.no |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Blood Vessels / cytology, ultrastructure Body Temperature / physiology* Brain / anatomy & histology, blood supply* Cerebrovascular Circulation / physiology* Coronary Angiography Diving / physiology* Heart Rate / physiology Pinnipedia / physiology* Seals, Earless / physiology |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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