AF rat model was established using acetylcholine (ACh)-CaCl2 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.
Results demonstrated that ranolazine attenuated AF in ACh-CaCl2-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.
The present study confirms the effects of ranolazine on AF rats induced by ACh-CaCl2, 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.