Abstract: AIM: To investigate the characterisics of atrial electrical remodeling induced by atrial fibrillation(AF) at molecular level.METHODS: Male SD rats were randomized into 2 equal groups. Rats of control group were administrated physiological saline (i.v.) for 7 days. The others were injected ACh-CaCl₂ (i.v.) for 7 days. AF duration and ECG parameters were measured. On day 8, all rats were anesthetized and the atriums were immediately excised for measuring AERP, the expression of Kv 1.5, Kv4.2/4.3, FKBP12.6 and Cx40 protein were detected using western-blot.RESULTS: In model rats, AF duration continually increased from day 1 to day 7 with ACh-CaCl₂ administration. The AERP of model group was shorter than that of control group [(65.3±3.6) ms vs (82.3±0.6) ms; P<0.01]. Western-blot showed that in the atrium, Kv1.5 and Kv4.2/4.3 expression was down-regulated after 7 days of AF induction, model rats expressed lower levels of Cx40 (P<0.05, vs control) and FKBP12.6 (P<0.05, vs control).CONCLUSION: AF induced by Ach-CaCl₂ injection for 7 days, has a stable AF duration, a shortened AERP with atrium ion channel, connexin and calcium regulation protein down-expressed, all of which related closely to the clinical characterics associated with AF.

Key words: Atrial fibrillation, Electrical remodeling, Connexin 40