OBJECTIVE:To compare the effects of Neiguan(PC6) acupuncture at different depths and reten-tion time on arrhythmia duration,myocardial tissue morphology,mRNA expression level of L-type calci-um channel α1C subunit and Ca2+-Mg2+-AtPase ac-tivity 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 Nei-guan (PC6) 20 min group (group G),deep needling Neiguan (PC6) 30 min group (group H),7 animals in each group.Electrocardiograms were used to col-lect the duration of arrhythmia;hematoxylin-eosin staining method was performed on myocardial tis-sue,RT-PCR tested the expression of α1C subunit mRNA,and the activity of Ca2 +-Mg2 +-ATPase were quantified by phosphorus determination method.RESULTS:The duration of arrhythmia in each acu-puncture treatment group was shortened to vary-ing degrees.Compare to the model group,the tis-sue damage from barium chloride inducing was im-proved 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 chan-nel α1C subunit mRNA expressions level and in-creased Ca2+-Mg2+-ATPase activity.CONCLUSIONS:The effect of acupuncture at Nei-guan (PC6) with different depths and retention time can reduce the duration of arrhythmia in-duced by barium chloride relatively,improve the in-duced pathological changes,down regulate L-type calcium channel α1C subunit mRNA expressions level and increase Ca2+-Mg2 +-ATPase activity.Both the shallow and deep tissues of Neiguan (PC6) may be involved in transmitting acupuncture informa-tion.There is an optimal induction period for shal-low needling at Neiguan (PC6) to reach the best therapeutic effect.