【Objective】 To study the effect of calcium transient alternan on the atrial fibrillation by rapid atrial pacing in canine.【Methods】 Rapid atrial pacing group (RAP group) and control group were involved. Atrial myocytes were isolated. The calcium transient in different frequent stimulation was studied using laser scan confocal microscope (LSCM). The time parameters of calcium transient and the threshold stimulative frequency of calcium transient alternan were measured. 【Results】 Comparing to control group

the threshold stimulative frequency (min-1) of calcium transient alternan in RAP group was significantly lower (86 ± 17 vs 123 ± 11

P < 0.01). And the atrial myocytes in RAP group more easily develop to subcellular disconcordant calcium transient alternan. Under the condition of 30 min-1 stimulation

the time to peak (ms) of calcium transient was significantly longer in RAP group (123 ± 1 vs 1110 ± 13

P = 0.001)

but the 90% decay time (ms) was not different (451 ± 79 vs 466 ± 81

P = 0.514). 【Conclusions】 Calcium transint alternan is correlated with rapid atrial pacing which is prone to atrial fibrillation. Calcium transient alternan may play an role in the formation of atrial fibrillation and may be determinated by L-type calcium channel (LCC)

ryanodine receptor (RyR) or their coupling.