Objective To investigate the molecular mechanism by which Linggui Zhugan Decoction (苓桂术甘汤, LGZGD) ameliorates heart failure (HF) after myocardial infarction (MI) via regulating mitophagy mediated by mitochondrial calcium uniporter (MCU)-mitochondrial calcium (mtCa²⁺) signaling pathway. Methods Rat models of post-MI HF and hydrogen peroxide (H₂O₂)-induced H9c2 cardiomyocyte injury models were established. For in vivo experiments, rats were assigned to sham group, model group, LGZGD group and captopril group. For in vitro experiments, H9c2 cells were divided into corresponding groups with additional interventions of MCU knockdown or overexpression. Echocardiography, Masson staining and transmission electron microscopy were performed to evaluate rat cardiac function, myocardial fibrosis and mitochondrial ultrastructure, respectively. The mRNA and protein expression levels of genes related to mitophagy and mitochondrial function were detected by qRT-PCR and Western blotting. The levels of reactive oxygen species (ROS) and mtCa²⁺ were measured, myocardial injury markers were quantitatively analyzed, and changes in cellular autophagic flux were observed using confocal laser scanning microscopy. Results Compared with sham group, rats with post-MI HF exhibited significantly impaired cardiac function, aggravated myocardial fibrosis and mitochondrial damage, dysregulated transcription of mitophagy-related genes, and markedly upregulated MCU transcription level (P < 0.001). In H₂O₂-stimulated H9c2 cells, ROS and mtCa²⁺ levels were significantly increased, autophagic flux was blocked, and myocardial injury marker levels were notably elevated (P < 0.01).Compared with model group, LGZGD treatment significantly improved cardiac function, alleviated myocardial fibrosis and mitochondrial damage, downregulated MCU expression (P < 0.01), regulated the mRNA expressions of autophagy and mitophagy-related genes in post-MI HF rats (P < 0.05, 0.01). At the cellular level, LGZGD reduced ROS and mtCa²⁺ levels in H₂O₂-injured H9c2 cells, restored mitochondrial morphology and autophagic flux, and decreased myocardial injury marker levels (P < 0.01). MCU knockdown enhanced the cardioprotective effect of LGZGD, whereas MCU overexpression exacerbated cellular injury. LGZGD effectively reversed MCU overexpression-induced cellular damage and ameliorated the dysregulation of oxidative stress-related enzymes (P < 0.05, 0.01). Conclusions LGZGD alleviates oxidative stress injury and improves post-MI heart failure by restoring MCU-mtCa²⁺ homeostasis and promoting mitochondrial autophagic flux.

Linggui Zhugan Decoction  /  heart failure  /  mitophagy  /  mitochondrial calcium uniporter  /  oxidative stress  /  pachymic acid B  /  cinnamic acid  /  atractylenolide III  /  glycyrrhetinic acid