| Hypoxic depression of circadian oscillations in sino-aortic denervated rats. | |
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MedLine Citation:
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PMID: 10936601 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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We hypothesized that hypoxia depresses the circadian oscillations of body temperature (T(b)) and oxygen consumption (V(O(2))) even in the absence of inputs from the peripheral chemoreceptors. Adult rats were sino-aortic denervated bilaterally (SAX, N=17) or sham-operated (Sham, N=17). Ten rats of each group were instrumented for measurements of T(b) and activity by telemetry. Animals were exposed to normoxia (21% O(2)), hypoxia (10.5% O(2)), and again normoxia, each for a 5-day duration, in constant light ('free-running') conditions. Hypoxia almost eliminated the T(b) circadian oscillations, mostly by abolishing the daily rise in T(b). Upon return to normoxia T(b) rapidly increased and the normal oscillation was reestablished at the expected phase of the cycle. The hypoxic effects did not differ between Sham and SAX. During hypoxia the amplitude of the circadian oscillation of activity was reduced by approximately 25%, and that of V(O(2)), measured by an open flow method in the remaining Sham and SAX rats (N=7 each), was reduced by almost 50%. In all cases there was no difference between the two groups. We conclude that activation of the peripheral chemoreceptors is not required for the manifestation of the hypoxic depression of the metabolic and temperature circadian oscillations. The results are compatible with the view that hypoxia depresses thermogenesis acting on the thermoregulatory centers of the hypothalamus. |
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Authors:
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K Fenelon; E L Seifert; J P Mortola |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Respiration physiology Volume: 122 ISSN: 0034-5687 ISO Abbreviation: Respir Physiol Publication Date: 2000 Aug |
Date Detail:
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Created Date: 2000-08-29 Completed Date: 2000-08-29 Revised Date: 2009-11-11 |
Medline Journal Info:
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Nlm Unique ID: 0047142 Medline TA: Respir Physiol Country: NETHERLANDS |
Other Details:
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Languages: eng Pagination: 61-9 Citation Subset: IM; S |
Affiliation:
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Department of Physiology, McGill University, McIntyre Basic Sciences Building, Room 1121, 3655 Drummond Street, Québec, Montreal, Canada H3G 1Y6. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Anoxia / physiopathology* Aorta / innervation Body Temperature Regulation Body Weight Carotid Sinus / innervation Circadian Rhythm Denervation Hematocrit Laryngeal Nerves / surgery Lung Volume Measurements Male Oxygen Consumption Rats Rats, Sprague-Dawley |
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