Ca2+/calmodulin‐dependent protein kinase II equally induces sarcoplasmic reticulum Ca2+ leak in human ischaemic and dilated cardiomyopathy. (8th September 2014)

• Record Type: Journal Article
• Authors: Fischer, Thomas H.; Eiringhaus, Jörg; Dybkova, Nataliya; Förster, Anna; Herting, Jonas; Kleinwächter, Astrid; Ljubojevic, Senka; Schmitto, Jan D.; Streckfuß‐Bömeke, Katrin; Renner, André; Gummert, Jan; Hasenfuss, Gerd; Maier, Lars S.; Sossalla, Samuel
• Is Part Of: European journal of heart failure. Volume 16:Number 12(2014)
• Page Start: 1292
• Page End: 1300
• Publication Date: 2014-09-08
• Subjects: Heart failure -- Periodicals; Heart Failure -- Periodicals; Insuffisance cardiaque -- Périodiques; Heart failure; Periodicals; 616.129005
• DOI: 10.1002/ejhf.163
• Languages: English
• ISSNs: 1388-9842

Abstract

<abstract abstract-type="main" id="ejhf163-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="ejhf163-sec-0001" sec-type="section"> <title>Aims</title> <p id="ejhf163-para-0001">The sarcoplasmic reticulum (SR) Ca<sup>2+</sup> leak is an important pathomechanism in heart failure (HF). It has been suggested that Ca<sup>2+</sup>/calmodulin‐dependent protein kinase II (CaMKII) is only relevant for the induction of the SR Ca<sup>2+</sup> leak in non‐ischaemic but not in ischaemic HF. Therefore, we investigated CaMKII and its targets as well as the functional effects of CaMKII inhibition in human ischaemic cardiomyopathy (ICM, <italic>n</italic> = 37) and dilated cardiomyopathy (DCM, <italic>n</italic> = 40).</p> </sec> <sec id="ejhf163-sec-0002" sec-type="section"> <title>Methods and results</title> <p id="ejhf163-para-0002">Western blots showed a significantly increased expression (by 54 ± 9%) and autophosphorylation at Thr286 (by 129 ± 29%, <italic>P</italic> < 0.05 each) of CaMKII in HF compared with healthy myocardium. However, no significant difference could be detected in ICM compared with DCM as to the expression and autophosphorylation of CaMKII nor the phosphorylation of the target sites ryanodine receptor 2 (RyR2)‐S2809, RyR2‐S2815, and phospholamban‐Thr17. Isolated human cardiomyocytes (CMs) of patients with DCM and ICM showed a similar frequency of diastolic Ca<sup>2+</sup> sparks (confocal microscopy) as well as of major arrhythmic events (Ca<sup>2+</sup> waves, spontaneous Ca<sup>2+</sup> transients). Despite a slightly smaller size of Ca<sup>2+</sup> sparks in DCM (<italic>P</italic> < 0.01), the calculated SR Ca<sup>2+</sup> leak [Ca<sup>2+</sup> spark frequecy (CaSpF) × amplitude × width × duration] did not differ between CMs of ICM vs. DCM. Importantly, CaMKII inhibition by autocamide‐2‐related inhibitory peptide (AIP, 1 µmol/L) reduced the SR Ca<sup>2+</sup> leak by ∼80% in both aetiologies (<italic>P</italic> < 0.05 each) and effectively decreased the ratio of arrhythmic cells (<italic>P</italic> < 0.05).</p> </sec> <sec id="ejhf163-sec-0003" sec-type="section"> <title>Conclusion</title> <p id="ejhf163-para-0003">Functional and molecular measures of the SR Ca<sup>2+</sup> leak are comparable in human ICM and DCM. CaMKII is equally responsible for the induction of the 'RyR2 leakiness' in both pathologies. Thus, CaMKII inhibition as a therapeutic measure may not be restricted to patients suffering from DCM but rather may be beneficial for the majority of HF patients.</p> </sec> </abstract>