Document Detail


Effects of thyroid hormone on action potential and repolarizing currents in rat ventricular myocytes.
MedLine Citation:
PMID:  10662715     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Thyroid hormones play an important role in cardiac electrophysiology through both genomic and nongenomic mechanisms of action. The effects of triiodothyronine (T(3)) on the electrophysiological properties of ventricular myocytes isolated from euthyroid and hypothyroid rats were studied using whole cell patch clamp techniques. Hypothyroid ventricular myocytes showed significantly prolonged action potential duration (APD(90)) compared with euthyroid myocytes, APD(90) of 151 +/- 5 vs. 51 +/- 8 ms, respectively. Treatment of hypothyroid ventricular myocytes with T(3) (0.1 microM) for 5 min significantly shortened APD by 24% to 115 +/- 10 ms. T(3) similarly shortened APD in euthyroid ventricular myocytes, but only in the presence of 4-aminopyridine (4-AP), an inhibitor of the transient outward current (I(to)), which prolonged the APD by threefold. Transient outward current (I(to)) was not affected by the acute application of T(3) to either euthyroid or hypothyroid myocytes; however, I(to) density was significantly reduced in hypothyroid compared with euthyroid ventricular myocytes.
Authors:
Z Q Sun; K Ojamaa; W A Coetzee; M Artman; I Klein
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  American journal of physiology. Endocrinology and metabolism     Volume:  278     ISSN:  0193-1849     ISO Abbreviation:  Am. J. Physiol. Endocrinol. Metab.     Publication Date:  2000 Feb 
Date Detail:
Created Date:  2000-03-02     Completed Date:  2000-03-02     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  100901226     Medline TA:  Am J Physiol Endocrinol Metab     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  E302-7     Citation Subset:  IM    
Affiliation:
Pediatric Cardiology, New York University Medical Center, New York 10016, USA.
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MeSH Terms
Descriptor/Qualifier:
4-Aminopyridine / pharmacology
Action Potentials / drug effects
Animals
Cadmium Chloride / pharmacology
Electric Conductivity
Heart / drug effects*,  physiopathology*
Heart Ventricles / drug effects,  physiopathology
Hypothyroidism / chemically induced,  physiopathology
Male
Patch-Clamp Techniques
Propylthiouracil
Rats
Rats, Sprague-Dawley
Triiodothyronine / pharmacology*
Triiodothyronine, Reverse / pharmacology
Grant Support
ID/Acronym/Agency:
HL-03775/HL/NHLBI NIH HHS; R01 HL-58849/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
10108-64-2/Cadmium Chloride; 504-24-5/4-Aminopyridine; 51-52-5/Propylthiouracil; 5817-39-0/Triiodothyronine, Reverse; 6893-02-3/Triiodothyronine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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