ObjectiveTo explore the protective effect of exercise-induced metabolite-3 (EIM-3) on myocardial ischemia-reperfusion (I/R) injury and explore its underlying molecular mechanisms.MethodsThe physicochemical properties and half-life of EIM-3 were analyzed using the Human Metabolome Database (HMDB, https://hmdb.ca/). A primary rat cardiomyocyte hypoxia/reoxygenation (H/R) injury model was established. Cell apoptosis and viability were assessed using TUNEL assay and cell counting kit-8, respectively. Lactate dehydrogenase (LDH) levels in the cell culture supernatant were measured. Intracellular reactive oxygen species (ROS) levels were detected. Transcriptomic analysis was performed to identify potential signaling pathways and targets of EIM-3.ResultsPlasma levels of EIM-3 were elevated post-exercise. EIM-3 was characterized as a phospholipid small-molecule compound with a partition coefficient (logP) of 5.58 and a solubility (logS) of -7.6, indicating favorable lipophilicity and cell membrane permeability. In cardiomyocytes H/R injury modles, EIM-3 significantly inhibited apoptosis, increased cell viability, reduced intracellular ROS levels, and decreased LDH release (P<0.01). Transcriptomic analysis suggested that EIM-3 exerts its protective function potentially by regulating glucose metabolim. Quantitative real-time polymerase chain reaction results confirmed that EIM-3 significantly upregulated the transcriptional level of pyruvate kinase M2 (PKM2) in a dose-dependent manner (P<0.001).ConclusionsEIM-3 protects cardiomyocytes against I/R injury by modulating glucose metabolim. This study provides foundational insights into the mechanisms underlying exercise-induced cardioprotection.