Effects of short-term median nerve stimulation on atrial electrophysiology and inflammation in canines with rapid atrial pacing

Abstract

Objective To investigate the effects of short-term median nerve stimulation (MNS) on the atrial electrophysiology and inflammation in canines with rapid atrial pacing. Methods According to the random number table, 24 mongrel dogs were used for the study as follows: control group (n=4), sham-operated group (n=6), MNS group (n=7) and MNS+ MLA (methyllycaconitine) group (n=7). The MLA is alpha 7 nicotinic acetylcholine receptor (α7nAChR) inhibitor.The control group did not take any intervention.The sham-operated group underwent rapid atrial pacing at 800 beats/min for 3 h. MNS Group underwent rapid atrial pacing combined with MNS for 3 h. MNS+ MLA Group underwent rapid atrial pacing combined with MNS and application of MLA (0.5 mg) on the epicardial surface of atrium and atrial appendages for 3 h. The atrial effective refractory period (AERP) and induced atrial fibrillation (AF) at baseline and every hour in the status of non-pacing were measured in dogs undergoing sham-operated group, MNS group and MNS+ MLA group.Then, the levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), acetylcholine (ACh) in the plasma and atrial tissues were measured.The control dogs were assigned to measure atrial inflammation cytokines. Results Compared with sham-operated group and MNS+ MLA group, the AERP were significantly prolonged (P 0.05; MNS+ MLA group: LA: (25.0±6.1) ng/ml vs.(27.0±6.2) ng/ml, RA: (23.0±5.9) ng/ml vs.(25.0±6.1) ng/ml, P>0.05]. Conclusion Short-term median nerve stimulation prevents the atrial electrophysiology changes and reduces the incidences of AF in canines with rapid atrial pacing, and decreases inflammatory cytokines levels, which might be associated with the cholinergic anti-inflammatory pathway. Key words: Atrial fibrillation; Median nerve; Cholinergic anti-inflammatory pathway; Inflammatory cytokines