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JTV519 (K201) reduces sarcoplasmic reticulum Ca 2+ leak and improves diastolic function in vitro in murine and human non‐failing myocardium
Author(s) -
Sacherer M,
Sedej S,
Wakuła P,
Wallner M,
Vos MA,
Kockskämper J,
Stiegler P,
Sereinigg M,
von Lewinski D,
Antoons G,
Pieske BM,
Heinzel FR
Publication year - 2012
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.2012.01995.x
Subject(s) - ryanodine receptor 2 , ryanodine receptor , calmodulin , ouabain , chemistry , medicine , endocrinology , phosphorylation , endoplasmic reticulum , diastole , calcium , biophysics , biology , biochemistry , blood pressure , organic chemistry , sodium
BACKGROUND AND PURPOSE Ca 2+ leak from the sarcoplasmic reticulum (SR) via ryanodine receptors (RyR2s) contributes to cardiomyocyte dysfunction. RyR2 Ca 2+ leak has been related to RyR2 phosphorylation. In these conditions, JTV519 (K201), a 1,4‐benzothiazepine derivative and multi‐channel blocker, stabilizes RyR2s and decrease SR Ca 2+ leak. We investigated whether JTV519 stabilizes RyR2s without increasing RyR2 phosphorylation in mice and in non‐failing human myocardium and explored underlying mechanisms. EXPERIMENTAL APPROACH SR Ca 2+ leak was induced by ouabain in murine cardiomyocytes. [Ca 2+ ]‐transients, SR Ca 2+ load and RyR2‐mediated Ca 2+ leak (sparks/waves) were quantified, with or without JTV519 (1 µmol·L −1 ). Contribution of Ca 2+ ‐/calmodulin‐dependent kinase II (CaMKII) was assessed by KN‐93 and Western blot (RyR2‐Ser 2814 phosphorylation). Effects of JTV519 on contractile force were investigated in non‐failing human ventricular trabeculae. KEY RESULTS Ouabain increased systolic and diastolic cytosolic [Ca 2+ ] i , SR [Ca 2+ ], and SR Ca 2+ leak (Ca 2+ spark (SparkF) and Ca 2+ wave frequency), independently of CaMKII and RyR‐Ser 2814 phosphorylation. JTV519 decreased SparkF but also SR Ca 2+ load. At matched SR [Ca 2+ ], Ca 2+ leak was significantly reduced by JTV519, but it had no effect on fractional Ca 2+ release or Ca 2+ wave propagation velocity. In human muscle, JTV519 was negatively inotropic at baseline but significantly enhanced ouabain‐induced force and reduced its deleterious effects on diastolic function. CONCLUSIONS AND IMPLICATIONS JTV519 was effective in reducing SR Ca 2+ leak by specifically regulating RyR2 opening at diastolic [Ca 2+ ] i in the absence of increased RyR2 phosphorylation at Ser 2814 , extending the potential use of JTV519 to conditions of acute cellular Ca 2+ overload.