Objective: To study the inhibitory effects of lipoic acid on rapid atrial pacing (RAP) induced atrial electrical remodeling and structural remodeling and its possible mechanism in rabbits. Methods: Forty-five New Zealand white rabbits were randomly divided into 3 groups: Sham operated group(sham group, n=10), RAP group(n=10), pacing+lipoic acid group (LA group, n=10). Pacemaker frequency was 600 times per min.Programmed electrical stimulation(PES) was performed in pacing 0, 4, 8 and 12 h, Atrial effective refractory period (AERP) was monitored, and the AERP frequency adaptability was calculated. The left atrial tissue was taken in the end of stimulus, the levels of the pathological atrial structural remodeling was observed by HE stainingand and the levels of oxidative stress in the atrium of each group was observed by measuring the levels of malondialdehyde (MDA), manganese superoxide dismutase(SOD) and reactive oxygen species(ROS). Results: The AERP at each time point in sham group did not change significantly at different base perimeter stimulation(P>0.05); compared with the sham group or RAP group, AERP in RAP group was gradually reduced (P<0.05); the rate adaptation of AERP were remarkably shortened in RAP group in pacing 8,12 h compared with 0 h(P<0.055). The rate adaptation of AERP did not change significantly in LA group(P>0.05). Atrial HE staining showed that atrial muscle fibers arranged in neat and orderly in the sham group, atrial muscle fibers were disordered and some were dissociated and ruptured in the RAP group. Atrial pathological changes of the LA group was lighter than the RAP group. Masson staining showed that red atrial fibers predominated, and only a small amount of blue collagen fibers were founed in the sham group,the content of collagen fibers in the interstitium of atrium was significantly increased and the distribution was disorder in the RAP group;the content of collagen fibers in the interstitium of atrium was improved in the LA group compared with the in RAP group. In the RAP group,the levels of atrium MDA and ROS were significantly increased and the SOD activity was significantly decreased compared with sham group(all P<0.05); In the LA group the levels of atrium MDA and ROS were decreased significantly, SOD activity was increased compared with the RAP(all P<0.05). Conclusion: LA intervention can inhibit atrial electrical remodeling and structural remodeling in rabbits rapid atrial pacing model.
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