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Aims Ranolazine, an antianginal agent used for chronic stable angina treatment, was demonstrated to be effective in atrial fibrillation (AF) treatment. The aim of this study was to explore the molecular mechanisms of its anti-AF effects. Main methods AF rat model was established using acetylcholine (ACh)-CaCl 2 injection for 7 days followed by ACh infusion into the heart. Prior to ACh infusion, ranolazine at 10.7 mg/kg/0.5 ml was injected into vein and followed by 0.56 mg/kg/min infusion. Blood pressure and electrocardiogram were monitored during the infusion. Histological changes of atrial tissue were observed after H&E staining. Activities and protein expression of NADPH oxidase-4, xanthine oxidase, glutathione peroxidase and superoxide dismutase were examined using commercial assay kits and Western botting, respectively. Mitochondrial functions were evaluated through membrane potential, ATP production, activities of complex I and III and reactive oxygen species production. Apoptosis was measured using TUNEL staining. Protein expression of apoptotic proteins Bcl-2, Bax and cleaved-caspase 3 and Akt/mTOR signaling proteins were detected using Western blotting. Key findings Results demonstrated that ranolazine attenuated AF in ACh-CaCl 2 -exposed rats. In addition, ranolazine restored mitochondrial function, suppressed oxidative stress, and inhibited atrial cells apoptosis. Furthermore, the activated Akt/mTOR signaling pathway induced by AF was further activated by ranolazine. Significance The present study confirms the effects of ranolazine on AF rats induced by ACh-CaCl 2 , and provides evidence that the anti-AF effects are associated with the restoration of mitochondrial function and activation of the Akt/mTOR signaling pathway in atrial tissue. [ABSTRACT FROM AUTHOR]