Carvedilol and its new analogs suppress arrhythmogenic store overload–induced Ca2+ release

Abstract

Carvedilol is one of the most effective beta-blockers for preventing ventricular tachyarrhythmias (VTs) in heart failure (HF), but the mechanisms underlying its favorable anti-arrhythmic benefits remain unclear. Spontaneous Ca2+ waves, also termed store-overload-induced Ca2+ release (SOICR), are known to evoke VTs in patients with HF. Here we show that carvedilol is the only beta-blocker that effectively suppresses SOICR by directly reducing the open duration of the cardiac ryanodine receptor (RyR2). This unique anti-SOICR activity of carvedilol combined with its beta-blocking activity likely contributes to its favorable anti-arrhythmic effect. To allow individual and optimal titration of these beneficial activities, we developed a novel SOICR-inhibiting, minimally-beta-blocking carvedilol analogue VK-II-86. We found that VK-II-86 alone prevented stress-induced VTs in RyR2 mutant mice, and was more effective when combined with a selective beta-blocker metoprolol or bisoprolol. Thus, SOICR inhibition combined with optimal beta-blockade presents a new, promising and potentially patient-tailorable anti-arrhythmic approach.

The EF-hand Ca2+ Binding Domain Is Not Required for Cytosolic Ca2+ Activation of the Cardiac Ryanodine Receptor

“…Single-cell Ca 2ϩ Imaging (Cytosolic Ca 2ϩ Measurements)-Cytosolic Ca 2ϩ levels in stable, inducible HEK293 cells expressing RyR2 WT or EF-hand mutants were monitored using single-cell Ca 2ϩ imaging and the fluorescent Ca 2ϩ indicator dye Fura-2/AM as described previously (22)(23)(24). Briefly, cells grown on glass coverslips for 8 -18 h after induction (as indicated) by 1 g/ml tetracycline (Sigma) were loaded with 5 M Fura-2/AM in KRH buffer (125 mM NaCl, 5 mM KCl, 6 mM glucose, 1.2 mM MgCl 2 , and 25 mM Hepes (pH 7.4)) plus 0.02% pluronic F-127 and 0.1 mg/ml BSA for 20 min at room temperature (23°C).…”

“…2ϩ Release in HEK293 Cells-RyR2-mediated Ca 2ϩ release can occur spontaneously during store Ca 2ϩ overload (18,(22)(23)(24). To determine whether the EF hand Ca 2ϩ binding motifs play a role in this spontaneous Ca 2ϩ release, also known as SOICR, we assessed the effect of the EF-hand mutations on SOICR.…”

“Early detection of Doxorubicin-induced Cardiotoxocity and its prevention by Carvedilol.”

“…Experimental and clinical evidences have revealed that carvedilol exerts antioxidant, antiproliferative, and antiapoptotic 17 along with cardioprotective effects. It has recently been shown to reduce morbidity and mortality in patients with chronic heart failure.…”

Microfluidic platform for bilayer experimentation

“…For instance, the ryanodine receptor (RyR) is an intracellular calcium channel involved in cardiovascular diseases, which is located in the membrane of the sarcoplasmic reticulum (ER). 38 This ion channel has been studied in a bilayer format for its electrophysiological characterization, 39 which has brought better insight into its function, through single RyR channel recordings. Measurements conducted on cells using a fluorescence approach only provide collective data on a channel population, with possible influence of RyR protein channels on each other.…”

“…The membrane thickness is assessed to be 4.43 ± 0.40 nm using a dielectric constant equal to 2.7, as reported in the literature for solvent-free DPhPC bilayers. 38 As the dielectric constant for n-decane is similar (2.0-2.1), 38,40 this value of 2.7 can be used in a first approximation for DPhPC membranes, although it might result in slightly higher values for the bilayer thickness.…”