Naringenin exerts antiarrhythmic action in septic cardiomyopathy by downregulating the CaMKⅡ/Drp1/Bcl-2 pathway.

Background: Septic cardiomyopathy (SCM) is associated with sepsis and is often accompanied by progressive arrhythmia. Naringenin (Nar) is a natural dihydroflavonoid compound that plays a protective role in various cardiovascular diseases. Calcium/calmodulin-dependent kinase II (CaMKII) is a key therapeutic target in cardiac arrhythmias.

Purpose: This study investigated the effect of naringenin on arrhythmia and cardiac electrophysiology in SCM and explored the mechanism involved.

Methods: Lipopolysaccharide was used to establish SCM in a mouse model and in an H9c2 cell line. The protective role of naringenin in SCM was investigated by pretreatment with naringenin, amiodarone, and a CaMKII inhibitor (KN-93). Cardiac function, susceptibility to arrhythmia, and electrophysiological changes were assessed in the mice using echocardiography, electrocardiography, and optical mapping techniques. Network pharmacology approaches, molecular docking, and molecular dynamics simulations were used to screen for pivotal targets. The mechanism(s) underlying the protective impact of naringenin on SCM were examined in vivo, ex vivo, and in vitro.

Results: Naringenin protected against SCM by exerting anti-inflammatory effects, alleviating myocardial injury, improving cardiac dysfunction, reducing the susceptibility to arrhythmia, and stabilizing electrophysiology. Network pharmacology, molecular docking, and molecular dynamics simulations indicated that the key target protein of naringenin may be Bcl-2. Further studies confirmed that naringenin attenuated apoptosis, improved mitochondrial dysfunction, and downregulated the CaMKⅡ/Drp1/Bcl-2 pathway in SCM.

Conclusions: Naringenin attenuates the phosphorylation of Drp1 by inhibiting phosphorylation of CaMKⅡ, thereby ameliorating mitochondrial dysfunction, suppressing apoptosis, modulating myocardial electrophysiology, and ultimately reducing susceptibility to arrhythmia while improving cardiac function in SCM.