Abstract: Objective To establish atrial fibrillation (AF) model in rabbit by intravenous injection of acetylcholine (Ach)-calcium chloride (CaCl₂) mixture. Methods AF in rabbit was induced by the intravenous administration of Ach (66 μg/mL)-CaCl₂ (10 mg/mL) in a pilot experiment. Duration of AF was recorded by electrocardiogram. Anesthetics, administration volume and rate of the Ach-CaCl₂ mixture were optimized by single-factor test. AF in rat was established by intravenous injection of Ach (66 μg/mL)-CaCl₂ (10 mg/mL) solution for 10 days. Atrial pathological changes were examined by Masson's trichrome and HE staining after 10 days, which were compared with the rat AF model. Results Pentobarbital sodium (0.5%) was injected as an anesthetic through the ear vein. A mixture of Ach (66 μg/mL)-CaCl₂ (10 mg/mL) (1 mL/kg) was administrated at a constant speed over 30 seconds for 10 days and 28 days to establish the rabbit atrial fibrillation model. Compared with the rat AF model, the duration of AF in rabbits was longer and fluctuated greatly. Furthermore, the compensatory effect was more obvious in rabbits treated with the mixture for 10 days, and the duration tended to be stable over time. In the 28 day modeling group, the duration of AF was approximately 80 seconds and atrial fibrosis was observed. Conclusions The rabbit atrial fibrillation model can be induced by the intravenous administration of Ach (66 μg/mL)-CaCl₂ (10 mg/mL). Compared with the AF in rat, AF in rabbit has a longer AF duration time, and the f-wave and ventricular wave of II lead electrocardiogram appear in AF, which is more similar to clinical.

Key words: Atrial fibrillation (AF), Ach-CaCl₂, Fibrosis, Rabbit, Rat