Initiation of cardiac hypertrophy in response to thyroxine is not limited by age

Robert J Tomanek; Carol A Butters; M Bridget Zimmerman

doi:10.1152/ajpheart.1993.264.4.H1041

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Initiation of cardiac hypertrophy in response to thyroxine is not limited by age

Journal article

Peer reviewed

Initiation of cardiac hypertrophy in response to thyroxine is not limited by age

Robert J Tomanek, Carol A Butters and M Bridget Zimmerman

The American journal of physiology, Vol.264(4 Pt 2), pp.H1041-H1047

04/1993

DOI: 10.1152/ajpheart.1993.264.4.H1041

PMID: 8476081

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Abstract

We examined the role of age in the initiation of thyroxine-induced (T4) cardiac hypertrophy. T4 (0.4 mg/kg sc) was administered to prepubescent (2 mo), young adult (6 mo), and senescent (24 mo) Fischer 344 rats for 4 days. While significant increases in left ventricular (LV) mass and RNA/LV were evident at 4 days in all T4-treated groups, the elevation in RNA/LV occurred earlier (2 days) in the senescent group. A 0.2-mg/kg dose of T4 elevated RNA values within 24 h in senescent, but not in prepubescent, rats. LV norepinephrine levels were measured to determine whether it plays a role in this model of cardiac hypertrophy. When synthesis of this catecholamine was blocked with alpha-methyl-p-tyrosine, tissue levels fell significantly in all groups, and the decrement was similar in T4-treated and control rats in the two younger groups. We conclude that: 1) the initiation of T4-induced cardiac hypertrophy is not compromised in senescent rats, 2) hearts of senescent rats respond earlier and to a lower dose of T4 than young rats, and 3) the cardiac hypertrophy that occurs in hyperthyroidism is not due to enhanced levels of available cardiac norepinephrine.

Myocardium - chemistry

Norepinephrine - physiology

Heart - physiology

Rats, Inbred F344

Rats

Male

Myocardium - pathology

Norepinephrine - analysis

Hemodynamics - physiology

Dose-Response Relationship, Drug

Thyroxine - adverse effects

Hypertrophy, Left Ventricular - chemically induced

Animals

Aging - physiology

DNA - analysis

Hypertrophy, Left Ventricular - physiopathology

Disease Models, Animal

Details

Title: Subtitle: Initiation of cardiac hypertrophy in response to thyroxine is not limited by age
Creators: Robert J Tomanek - Department of Anatomy, University of Iowa, Iowa City 52242
Carol A Butters
M Bridget Zimmerman
Resource Type: Journal article
Publication Details: The American journal of physiology, Vol.264(4 Pt 2), pp.H1041-H1047
DOI: 10.1152/ajpheart.1993.264.4.H1041
PMID: 8476081
NLM abbreviation: Am J Physiol
ISSN: 0002-9513
eISSN: 2163-5773
Publisher: American Physiological Society; United States
Grant note: HL-18629 / NHLBI NIH HHS HL-14388 / NHLBI NIH HHS
Language: English
Date published: 04/1993
Academic Unit: Anatomy and Cell Biology; Biostatistics
Record Identifier: 9983997474402771

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