Fuling Xingren Gancao Decoction ameliorates myocardial ischemia/reperfusion injury by attenuating calcium overload and modulating inflammatory signaling mediated by calcium/calmodulin-dependent protein kinase II delta.

ETHNOPHARMACOLOGICAL RELEVANCE Fuling Xingren Gancao Decoction (FXGD) is a classic prescription derived from the Synopsis of the Golden Chamber, traditionally used to treat chest obstruction with pain, and has been clinically applied in Chinese medicine and Japanese Kampo practice for ischemic heart disease. Beyond East Asia, its constituent medicinal materials are also recognized in European and Eurasian official pharmacopoeial frameworks. Experimental evidence also supports the cardioprotective activities of these medicinal materials. However, the underlying mechanisms of FXGD against myocardial ischemia/reperfusion injury (MIRI) have not yet been clarified.

Aim

OF THE STUDY This study was performed to investigate the protective effects of FXGD against MIRI and to explore the potential underlying molecular mechanisms.

Materials And Methods

Liquid chromatography-mass spectrometry was employed for the identification of the chemical components of FXGD. A rat MIRI model was established via reversible ligation of the left anterior descending coronary artery of rats, and an in vitro hypoxia/reoxygenation (H/R) injury model was established in H9c2 cells. Following FXGD pretreatment, the cardioprotection and potential mechanisms were explored by systematically evaluating the cardiac electrophysiology, cardiac function, biochemical parameters, histopathological changes, oxidative stress, inflammation, and apoptosis in the above models.

Results

FXGD significantly reduced myocardial infarct size and myocardial injury biomarker levels, including cardiac troponin I, cardiac troponin T, lactate dehydrogenase, and creatine kinase-MB, while mitigating myocardial structural damage and improving cardiac function in MIRI rats. FXGD also shortened the prolonged QT interval and QRS duration, improved myocardial electrical conduction, alleviated the heterogeneity of action potentials and calcium transients, and decreased susceptibility to arrhythmias. Patch-clamp recording results demonstrated that FXGD inhibited L-type calcium current in a concentration-dependent manner, with a half-maximal inhibitory concentration of 0.026 mg/mL, and exerted no significant effect on the steady-state activation or inactivation properties. Furthermore, FXGD reduced the levels of reactive oxygen species and malondialdehyde, restored the activity of antioxidant enzymes, suppressed the production of inflammatory factors and cardiomyocyte apoptosis, and inhibited the calcium/calmodulin-dependent protein kinase II delta (CaMKIIδ)/nuclear factor-κB (NF-κB)/NOD-like receptor family pyrin domain-containing 3 (NLRP3) pathway. Consistent protective effects were observed in H/R-injured H9c2 cells, and the involvement of CaMKIIδ was further supported by treatment with the inhibitor KN93.

Conclusions

FXGD exerts cardioprotective effects against MIRI, potentially through attenuation of calcium overload and modulation of the CaMKIIδ/NF-κB/NLRP3 signaling pathway, thereby suppressing oxidative stress, inflammatory responses, and cardiomyocyte apoptosis. However, because the pharmacological validation was performed using a single standardized experimental batch, the reproducibility of these findings across different batches, harvest years, and geographic origins requires further confirmation.