| Is increased metabolism in rats in the cold mediated by the thyroid? | |
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MedLine Citation:
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PMID: 2100316 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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1. In the rat variation of metabolic heat production is the principal effector of thermoregulation. There is a continuous relationship between ambient temperature and metabolic rat over the whole range of tolerable environmental temperature. The mechanism that controls metabolic rate is unknown; this paper reports an attempt to test whether thyroid hormones provide the controlling pathway. 2. First, the changes in metabolic rate and in the plasma concentrations of thyroid stimulating hormone (TSH), triiodothyronine (T3) and thyroxine (T4) were measured in rats living in a controlled environment, first at 23 degrees C and then at 6 degrees C. Metabolic rate increased from approximately 290 to 470 kJ day-1 when the temperature was lowered, a factor of ca 1.6, and the diurnal rhythm disappeared. The concentration of TSH increased from approximately 320 to 450 ng ml-1 (with loss of diurnal rhythm) and of T3 from ca 0.7 to 1.0 nmol l-1, a factor of ca 1.4 in each case. T4 concentration did not change. 3. Next, a dose schedule of T3 was found that, when injected I.V. via indwelling jugular cannulae in the same rats in an environment at 23 degrees C, maintained an increase in T3 concentration rather greater than had been found at 6 degrees C. 4. This dose of T3, given to the same rats at 23 degrees C, did not affect metabolic rate (or its diurnal pattern). 5. It is therefore unlikely that the increase in T3 concentration evoked the increase in metabolic rate when ambient temperature was changed from 23 to 6 degrees C; and therefore that the thyroid controls variation of metabolic rate in 'everyday' thermoregulation in the rat. |
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Authors:
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E M Whitaker; S H Hussain; G R Hervey; G Tobin; K M Rayfield |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: The Journal of physiology Volume: 431 ISSN: 0022-3751 ISO Abbreviation: J. Physiol. (Lond.) Publication Date: 1990 Dec |
Date Detail:
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Created Date: 1991-08-22 Completed Date: 1991-08-22 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 0266262 Medline TA: J Physiol Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 543-56 Citation Subset: IM |
Affiliation:
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Department of Physiology, University of Leeds. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Circadian Rhythm / physiology Cold Temperature* Energy Metabolism / drug effects, physiology* Male Rats Rats, Inbred Strains Thyroid Hormones / blood, physiology* Time Factors Triiodothyronine / pharmacology |
| Chemical | |
Reg. No./Substance:
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0/Thyroid Hormones; 6893-02-3/Triiodothyronine |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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