| Thyroxine secretion rates during pregnancy in the rat. | |
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MedLine Citation:
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PMID: 7882897 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Thyroxine secretion rates (TSR) at various stages of pregnancy in rats were measured by the radiothyroxine pool-turnover method. Groups of rats included normal controls (non-pregnant), days 5, 10, 20, and 22 of pregnancy and near term (within 24 hours prior to parturition if past 22 days of pregnancy). Each animal had blood samples taken just prior to injection of 10 microCi L-thyroxine (L-T4)-131I and at 12, 24, 36, and 48 hours afterwards. Determinations of thyroxine iodine (T4-I), volume of distribution (VD), fractional turnover rate (K), and L-T4 pool size were made from these samples. TSR was calculated as the product of (1.54) (T4-I) (VD) (K). An increase in TSR occurred near term, 3.65 micrograms L-T4/day compared to 1.23 micrograms L-T4/day in the controls, was primarily due to an increase in VD from 33.9 ml in the controls to 90.0 ml near term. A rapid increase in TSR to 3.65 micrograms L-T4/day just prior to term was postulated to be due to a stimulatory action of relaxin in the presence of estrogen upon L-T4 utilization. The mechanism of the increase in TSR in pregnant rats is probably due to the effect of several hormonal changes in maternal tissues throughout pregnancy and to adaptation of the pregnant animals to higher metabolic needs of the rapid developing fetuses. |
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Authors:
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M H Lu; R R Anderson |
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Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Review |
Journal Detail:
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Title: Endocrine research Volume: 20 ISSN: 0743-5800 ISO Abbreviation: Endocr. Res. Publication Date: 1994 Nov |
Date Detail:
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Created Date: 1995-04-12 Completed Date: 1995-04-12 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 8408548 Medline TA: Endocr Res Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 343-64 Citation Subset: IM |
Affiliation:
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Department of Dairy Husbandry University of Missouri-Columbia 65201. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Female Pregnancy Pregnancy, Animal / blood* Rats Rats, Sprague-Dawley Thyroxine / analysis, blood, pharmacokinetics, pharmacology, secretion* Time Factors |
| Chemical | |
Reg. No./Substance:
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7488-70-2/Thyroxine |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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