Empagliflozin reduces Ca/calmodulin‐dependent kinase II activity in isolated ventricular cardiomyocytes

Abstract

AimsThe EMPA‐REG OUTCOME study showed reduced mortality and hospitalization due to heart failure (HF) in diabetic patients treated with empagliflozin. Overexpression and Ca2+‐dependent activation of Ca2+/calmodulin‐dependent kinase II (CaMKII) are hallmarks of HF, leading to contractile dysfunction and arrhythmias. We tested whether empagliflozin reduces CaMKII‐ activity and improves Ca2+‐handling in human and murine ventricular myocytes.Methods and resultsMyocytes from wild‐type mice, mice with transverse aortic constriction (TAC) as a model of HF, and human failing ventricular myocytes were exposed to empagliflozin (1 μmol/L) or vehicle. CaMKII activity was assessed by CaMKII–histone deacetylase pulldown assay. Ca2+ spark frequency (CaSpF) as a measure of sarcoplasmic reticulum (SR) Ca2+ leak was investigated by confocal microscopy. [Na+]i was measured using Na+/Ca2+‐exchanger (NCX) currents (whole‐cell patch clamp). Compared with vehicle, 24 h empagliflozin exposure of murine myocytes reduced CaMKII activity (1.6 ± 0.7 vs. 4.2 ± 0.9, P < 0.05, n = 10 mice), and also CaMKII‐dependent ryanodine receptor phosphorylation (0.8 ± 0.1 vs. 1.0 ± 0.1, P < 0.05, n = 11 mice), with similar results upon TAC. In murine myocytes, empagliflozin reduced CaSpF (TAC: 1.7 ± 0.3 vs. 2.5 ± 0.4 1/100 μm−1 s−1, P < 0.05, n = 4 mice) but increased SR Ca2+ load and Ca2+ transient amplitude. Importantly, empagliflozin also significantly reduced CaSpF in human failing ventricular myocytes (1 ± 0.2 vs. 3.3 ± 0.9, P < 0.05, n = 4 patients), while Ca2+ transient amplitude was increased (F/F0: 0.53 ± 0.05 vs. 0.36 ± 0.02, P < 0.05, n = 3 patients). In contrast, 30 min exposure with empagliflozin did not affect CaMKII activity nor Ca2+‐handling but significantly reduced [Na+]i.ConclusionsWe show for the first time that empagliflozin reduces CaMKII activity and CaMKII‐dependent SR Ca2+ leak. Reduced Ca2+ leak and improved Ca2+ transients may contribute to the beneficial effects of empagliflozin in HF.

Evaluation of the effect of sodium–glucose co‐transporter 2 inhibition with empagliflozin on morbidity and mortality of patients with chronic heart failure and a reduced ejection fraction: rationale for and design of the EMPEROR‐Reduced trial

“…Instead, it has been proposed that SGLT2 inhibitors may slow the course of cardiomyocyte injury and loss by inhibiting the sodium–hydrogen exchanger‐1 (NHE‐1) in the myocardium, whose overactivity may lead to increases in intracellular sodium and calcium, which can impair cardiomyocyte function and viability . Interestingly, empagliflozin has also been shown to inhibit the activation of Ca++/calmodulin‐dependent kinase II, which contributes to the activation of NHE‐1 in the heart . The actions of empagliflozin to prevent calcium overload may explain why the drug prevents the time‐dependent decline in systolic cardiac function seen in experimental pressure overload‐induced heart failure …”

“…[26][27][28][29][30][31] Interestingly, empagliflozin has also been shown to inhibit the activation of Ca++/calmodulin-dependent kinase II, which contributes to the activation of NHE-1 in the heart. [32][33][34] The actions of empagliflozin to prevent calcium overload may explain why the drug prevents the time-dependent decline in systolic cardiac function seen in experimental pressure overload-induced heart failure. 35,36 Regardless of the mechanisms that might be in play, the EMPEROR-Reduced trial is well-positioned to determine if the addition of SGLT2 inhibitors could add meaningfully to current approaches that have established benefits in the treatment of chronic heart failure.…”

Empagliflozin, calcium, and SGLT1/2 receptor affinity: another piece of the puzzle

“…An interesting novel mode of action for empaglifozin has now been suggested by Mustroph et al . In this issue of the ESC Heart Failure , they show for the first time that empagliflozin potently reduces Ca 2+ /calmodulin‐dependent kinase (CaMKII) activity in isolated failing and non‐failing murine ventricular myocytes.…”

“…But let us have a closer look into empaglifozin itself and how it may differentiate from others in the class of SGLT2 inhibitors. Interestingly, the authors also report that in contrast to a robust SGLT2 expression in murine kidney, no SGLT‐2 signal was detected in human or mice myocardium. So does SGLT2 expression in the heart matter?…”

“…3,7 All these mechanisms may deal with different co-morbidity aspects of patients with T2DM that lead to the development or deterioration of HF. [8][9][10][11] An interesting novel mode of action for empaglifozin has now been suggested by Mustroph et al 12 In this issue of the ESC Heart Failure, they show for the first time that empagliflozin potently reduces Ca 2+ /calmodulin-dependent kinase (CaMKII) activity in isolated failing and non-failing murine ventricular myocytes. Importantly, empagliflozin also reduced CaMKII-dependent phosphorylation of the cardiac ryanodine receptor (RyR2) not only in murine but also in failing human ventricular myocytes.…”