[Effect of acupuncture at different layers of local "Neiguan" (PC6) tissue on arrhythmia and expression of myocardial Cx43 in rabbits].

Objective: To compare the therapeutic effect of shallow and deep needling at "Neiguan"(PC6) in the treatment of arrhythmia in rabbits.

Methods: Male New Zealand rabbits were randomly divided into saline (＝15), model (＝12), shallow needling (＝13) and deep needling (＝12) groups. The arrhythmia model was established by ear intravenous injection of Barium chloride (0.4%, 1 mL/kg). Acupuncture needle was inserted into the superficial fascia (about 3 mm beneath the skin) or deep layer (5 to 8 mm, near the median nerve) of local PC6 tissue (fore limb), manipulated for a while and then retained for 10 min. Histopathological changes of myocardium was observed after H．E. stain, and the immunoactivity of connexin 43 (Cx43) detected by immunohistochemistry(IHC).

Results: Various degrees of arrhythmia and down-regulated expression of myocardial Cx43 were observed in all rabbits after modeling. After EA intervention and compared with the model group, the initial time of arrhythmia and Cx43 expression were obviously increased (<0.01), and the duration of arrhythmia was significantly shortened in both deep and shallow needling groups (<0.01). Compared with the shallow needling group, the Cx43 expression was increased in the deep needling group (<0.01). H．E. staining showed disordered and wavy arrangement of myocardial fibers, with exudation of serous and erythrocytes in the myocardial interstitium in the model group, which was relatively mild in both needling groups. IHC showed disordered distribution of Cx43 in the ventricular myocytes and almost no obvious band-like distribution at the discs in rabbits of the model group, and abundant distribution of Cx43 in the sacral disc in the deep needling group, and strip-shaped, cluster-like, point-like, visible at both end-to-end connections and side-to-side connections in the shallow needling group.

Conclusion: Both shallow and deep needling can significantly reduce the duration of arrhythmia in arrhythmia rabbits, which may be associated with its effect in up-regulating expression of myocardial Cx43 protein.