Abstract: OBJECTIVE:To compare the effects of Neiguan(PC6) acupuncture at different depths and retention time on arrhythmia duration, myocardial tissue morphology, mRNA expression level of L-type calcium channel α1C subunit and Ca~(2+)-Mg~(2+)-At Pase activity in tachirrhythmia model of rabbits.METHODS:The tachyarrhythmia model was made by intravenous injection of barium chloride into the ears of rabbits. A total of 56 healthy adult male New Zealand big-eared white rabbits, apply the random number table method, divided into normal control group(group A), model group(group B),shallow needling Neiguan(PC6) 10 min group(group C), shallow needling Neiguan(PC6) 20 min group(group D), shallow needling Neiguan(PC6)30 min group(group E), deep needling Neiguan(PC6) 10 min group(group F), deep needling Neiguan(PC6) 20 min group(group G), deep needling Neiguan(PC6) 30 min group(group H), 7 animals in each group. Electrocardiograms were used to collect the duration of arrhythmia; hematoxylin-eosin staining method was performed on myocardial tissue, RT-PCR tested the expression of α1C subunit mRNA, and the activity of Ca~(2+)-Mg~(2+)-ATPase were quantified by phosphorus determination method.RESULTS:The duration of arrhythmia in each acupuncture treatment group was shortened to varying degrees. Compare to the model group, the tissue damage from barium chloride inducing was improved in the acupuncture group. Compared to the model group, except for group E, most treatment groups had varying degrees of improvement with significantly down-regulated L-type calcium channel α1C subunit mRNA expressions level and increased Ca~(2+)-Mg~(2+)-ATPase activity.CONCLUSIONS:The effect of acupuncture at Neiguan(PC6) with different depths and retention time can reduce the duration of arrhythmia induced by barium chloride relatively, improve the induced pathological changes, down regulate L-type calcium channel α1C subunit mRNA expressions level and increase Ca~(2+)-Mg~(2+)-ATPase activity. Both the shallow and deep tissues of Neiguan(PC6) may be involved in transmitting acupuncture information. There is an optimal induction period for shallow needling at Neiguan(PC6) to reach the best therapeutic effect.

Key words: Point PC6(Neiguan), arrhythmias,cardiac, calcium channels,L-type, Ca~(2+)-Mg~(2+)-ATPase, needle retention time