Empagliflozin attenuates doxorubicin-impaired cardiac contractility by suppressing reactive oxygen species in isolated myocytes.

In animal studies, sodium-glucose co-transporter-2 inhibitors-such as empagliflozin-have been shown to improve heart failure and impaired cardiac contractility induced by anthracyclines-including doxorubicin-although the therapeutic mechanism remains unclear. Moreover, abnormalities in Ca handling within ventricular myocytes are the predominant feature of heart failure. Accordingly, this study aimed to investigate whether empagliflozin can alleviate Ca handling disorders induced by acute doxorubicin exposure and elucidate the underlying mechanisms. To this end, ventricular myocytes were isolated from C57BL/6 mice. Contraction function, Ca handling, and mitochondrial reactive oxygen species (ROS) generation were then evaluated using IonOptix or confocal microscopy. Ca handling proteins were detected by western blotting. Results show that incubation with 1 μmol/L of doxorubicin for 120-min impaired cardiac contractility in isolated myocytes, which was significantly alleviated by pretreatment with 1 μmol/L of empagliflozin. Doxorubicin also markedly induced Ca handling disorders, including decreased Ca transients, prolonged Ca transient decay time, enhanced frequency of Ca sparks, and decreased Ca content in the sarcoplasmic reticulum. These dysregulations were improved by pretreatment with empagliflozin. Moreover, empagliflozin effectively inhibited doxorubicin-induced mitochondrial ROS production in isolated myocytes and rescued doxorubicin-induced oxidation of Ca/calmodulin-dependent protein kinase II (ox-CaMKII) and CaMKII-dependent phosphorylation of RyR2. Similarly, preincubation with 10 μmol/L Mito-TEMPO mimicked the protective effects of empagliflozin. Collectively, Empagliflozin ameliorated the doxorubicin-induced contraction malfunction and Ca-handling disorders. These findings suggest that empagliflozin alleviates Ca-handling disorders by improving ROS production in the mitochondria and alleviating the enhanced oxidative CaMKII signaling pathway induced by doxorubicin.