Abstract
<title>Abstract</title> <p>Doxorubicin (DOX), a common chemotherapeutic agent, leads to irreversible anthracycline-induced cardiomyopathy (AIC). Impaired mitochondrial quality control serves as a central pathogenic driver of AIC. Meanwhile, DOX provokes sustained overactivation of the TRPC6/NFAT cascade, generating self-amplifying excitation-transcription feedback within injured cardiomyocytes. Despite the well-documented cardioprotective potential of aerobic exercise, the causal interplay between TRPC6/NFAT signaling and mitochondrial homeostasis underlying this protection remains unclear. Male C57BL/6J mice were randomly assigned to five groups with bidirectional pharmacological manipulation of TRPC6/NFAT activity: control, DOX, exercise+DOX, exercise+DOX+TRPC6 agonist hyperforin, and DOX+TRPC6 antagonist larixyl acetate. Aerobic exercise suppressed TRPC6/NFAT3 overactivation. This inhibition further normalized mitochondrial quality control by enhancing mitochondrial biogenesis, limiting excessive mitochondrial fission and restoring physiological mitophagy. Improved mitochondrial homeostasis subsequently attenuated DOX-elicited myocardial injury, hypertrophy and interstitial fibrosis. Echocardiography revealed restored systolic function with elevated left ventricular ejection fraction (LVEF) and fractional shortening (LVFS). Treadmill testing further revealed recovered heart rate recovery (HRR), alongside longer exhaustive running distance and exercise duration. Notably, larixyl acetate recapitulated all exercise-conferred cardiac benefits, whereas hyperforin-mediated TRPC6/NFAT activation completely abrogated exercise-induced protection. Collectively, aerobic exercise alleviates DOX-induced cardiomyopathy by disrupting the TRPC6/NFAT3 positive-feedback loop to restore mitochondrial quality control. This cascade of effects mitigates pathological myocardial remodeling, rescues left ventricular systolic performance and boosts systemic exercise tolerance, providing experimental evidence supporting exercise rehabilitation for patients with AIC.</p>