Intracellular dyssynchrony of diastolic cytosolic [Ca²âº] decay in ventricular cardiomyocytes in cardiac remodeling and human heart failure.
Circ Res
; 113(5): 527-38, 2013 Aug 16.
Article
em En
| MEDLINE
| ID: mdl-23825358
ABSTRACT
RATIONALE Synchronized release of Ca²âº into the cytosol during each cardiac cycle determines cardiomyocyte contraction. OBJECTIVE:
We investigated synchrony of cytosolic [Ca²âº] decay during diastole and the impact of cardiac remodeling. METHODS ANDRESULTS:
Local cytosolic [Ca²âº] transients (1-µm intervals) were recorded in murine, porcine, and human ventricular single cardiomyocytes. We identified intracellular regions of slow (slowCaR) and fast (fastCaR) [Ca²âº] decay based on the local time constants of decay (TAUlocal). The SD of TAUlocal as a measure of dyssynchrony was not related to the amplitude or the timing of local Ca²âº release. Stimulation of sarcoplasmic reticulum Ca²âº ATPase with forskolin or istaroxime accelerated and its inhibition with cyclopiazonic acid slowed TAUlocal significantly more in slowCaR, thus altering the relationship between SD of TAUlocal and global [Ca²âº] decay (TAUglobal). Naâº/Ca²âº exchanger inhibitor SEA0400 prolonged TAUlocal similarly in slowCaR and fastCaR. FastCaR were associated with increased mitochondrial density and were more sensitive to the mitochondrial Ca²âº uniporter blocker Ru360. Variation in TAUlocal was higher in pig and human cardiomyocytes and higher with increased stimulation frequency (2 Hz). TAUlocal correlated with local sarcomere relengthening. In mice with myocardial hypertrophy after transverse aortic constriction, in pigs with chronic myocardial ischemia, and in end-stage human heart failure, variation in TAUlocal was increased and related to cardiomyocyte hypertrophy and increased mitochondrial density.CONCLUSIONS:
In cardiomyocytes, cytosolic [Ca²âº] decay is regulated locally and related to local sarcomere relengthening. Dyssynchronous intracellular [Ca²âº] decay in cardiac remodeling and end-stage heart failure suggests a novel mechanism of cellular contractile dysfunction.Palavras-chave
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1
Coleções:
01-internacional
Base de dados:
MEDLINE
Limite:
Animals
/
Humans
Idioma:
En
Ano de publicação:
2013
Tipo de documento:
Article