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3,5,3′-Triiodothyronine deprivation affects phenotype and intracellular [Ca2+ ] of human


3,5,3′-Triiodothyronine deprivation affects phenotype and intracellular [Ca2+]i of human cardiomyocytes in culture

Abstract

OBJECTIVE:
A decrease in plasma T3 concentration is a frequent finding in patients with heart failure. However, the role of this ‘low T3 syndrome’ on disease evolution has never been clarified. As phenotypic and functional cardiomyocyte impairments are alterations that correlate with the failing myocardium, we studied the long-term effects of T3 deprivation on human cardiomyocyte structure and calcium handling.

METHODS:
Atrial cardiomyocytes and myocardial tissue were cultured with or without 3 nM T3. Microscopical examination of structural features was followed by analysis of alpha-sarcomeric actinin and sarcoplasmic reticulum calcium ATP-ase (SERCA-2) content. Calcium handling was studied by [Ca2+](i) imaging.

RESULTS:
When stimulated with cyclopiazonic acid, a SERCA-2 inhibitor, T3-deprived cardiomyocytes showed significantly faster (P=0.03) and more transient (P=0.04) increases in [Ca(2+)](i) than T3-supplemented cells. Moreover, in the T3-free cultures a significantly lower number of cells (P=0.003) responded to caffeine, a typical activator of sarcoplasmic reticulum Ca(2+)-release channel. T3-deprived cardiomyocytes also presented altered morphology with larger dimensions than T3-supplemented cells (P < 0.0001). Additionally, in T3-deprived samples alpha-sarcomeric actinin and SERCA-2 protein levels were reduced to 65.6 +/- 3% (P < 0.0001) and 74.1 +/- 4% (P=0.005), respectively, when compared with the T3-supplemented group. CONCLUSIONS:
Our data show that human cardiomyocyte calcium handling and phenotype are strongly influenced by T3 suggesting important implications of the ‘low T3 syndrome’ on the progression of heart failure.

Cardiovasc Res. 2001 Aug 1;51(2):322-30.
http://cardiovascres.oxfordjournals.org/content/51/2/322.full.pdf+html

Nicolini/Ier asi/Fiorini have also written an updated article (as of 2013):-

http://www.ncbi.nlm.nih.gov/pubmed/23555069

in a Special Issue of the Journal of Thyroid Research

http://www.hindawi.com/journals/jtr/si/870510/
New insights into mechanisms of cardioprotection mediated by thyroid hormones.citing other recent work:-
Molecular basis of physiological heart growth: fundamental concepts and new playersMarjorie Maillet, Jop H. van Berlo & Jeffery D. Molkentin

p38 | doi:10.1038/nrm3495

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