Objective To study the influence of medicated serum of Qiangxin Fumai Fang on action potential of injured sino-atrial node cells (SNC) in neonatal rats. Methods SNC were isolated in Wistar neonatal rats and divided into 6 groups including normal group (group 1), model group (group 2), 100 l medicated serum group (group 3), 200 l medicated serum group (group 4), 300 l medicated serum group (group 5) and blank serum group (group 6). Except of group 1, other groups were given simulating ischemia-reperfusion (I-R) for establishing cell injury model. The cell spontaneous action potential was recorded by using patch clamp technique under current clamp mode in all groups. The durations from repolarization to 20%action potential (APD20), 50%action potential (APD50) and 90%action potential (APD90), the maximal diastolic potential (MDP), and action potential amplitude (APA) were detected in all groups. Results Compared with group 2, APD20 was shortened in group 3, group 4 and group 5 [(77.2 ±5.5) ms vs. (35.7±7.1) ms], [(77.2±5.5) ms vs. (50.1±7.5) ms], [(77.2±5.5) ms vs. (39.7±4.3) ms, all P<0.01], and APD50 was shortened in group 3, group 4 and group 5 [(147.5±5.1) ms vs. (90.6±5.8) ms], [(147.5±5.1) ms vs. (111.0±4.1) ms], [(147.5±5.1) ms vs. (109.0±2.4) ms, all P<0.05]. Compared with group 1, MDP increased and APA decreased in group 2 [(-61.9±5.4) mV vs. (-54.5±4.6) mV], [(84.7±5.0) mV vs. (71.4±4.7) mV, all P<0.01]. Compared with group 2, MDP had no significant changes in group 3, group 4 and group 5 (all P>0.05). APA increased in group 3 and group 5 compared with group 2 [(83.2±5.9) mV vs. (71.4±4.7) mV], [(82.2±6.4) mV vs. (71.4±4.7) mV, all P<0.01]. Conclusion The medicated serum of Qiangxin Fumai Fang can shorten APD20 and APD50 of action potential of injured SNC, increased APA, shorten duration of action potential, and improve frequency of spontaneous beat in neonatal rats.%目的：研究强心复脉方含药血清对乳鼠受损窦房结细胞动作电位的影响。方法分离培养Wistar乳鼠窦房结细胞，分为6组：正常组、模型组、100μl含药血清组、200μl含药血清组、300μl含药血清组、空白血清组。除正常组外，其余各组均模拟缺血-再灌注制备细胞损伤模型。采用膜片钳技术在电流钳模式下记录各组细胞自发性动作电位，测量各组细胞复极至20%、50%、90%动作电位时程（APD20、APD50、APD90）、最大舒张电位（MDP）及动作电位幅值（APA）。结果于造模后细胞外液分别加入100μl、200μl、300μl强心复脉方含药血清，与模型组比较，100μl含药血清组、200μl含药血清组、300μl含药血清组APD20缩短，分别为[（77.2±5.5）ms vs.（35.7±7.1）ms]、[（77.2±5.5） ms vs.（50.1±7.5）ms]、[（77.2±5.5）ms vs.（39.7±4.3）ms]，差别均具有统计学意义（P均＜0.01）；APD50缩短，分别为[（147.5±5.1）ms vs.（90.6±5.8）ms]、[（147.5±5.1）ms vs.（111.0±4.1）ms]、[（147.5±5.1）ms vs.（109.0±2.4）ms]，差别均具有统计学意义（P均＜0.05）。与正常组比较，经缺血-再灌注造模后（模型组）细胞的MDP上升，APA减小，为[（-61.9±5.4）mV vs.（-54.5±4.6）mV]，[（84.7±5.0）mV vs.（71.4±4.7）mV]，差异均具有显著性统计学意义（P均＜0.01）。于造模后细胞外液分别加入100μl、200μl、300μl强心复脉方含药血清，与模型组比较，各组MDP值无明显改变，无统计学意义（P均＞0.05）。100μl含药血清组和300μl含药血清组APA均较模型组增大，分别为[（83.2±5.9）mV vs.（71.4±4.7）mV]和[（82.2±6.4）mV vs.（71.4±4.7）mV]，差异均具有显著统计学意义（P均＜0.01）。结论强心复脉方含药血清能缩短乳鼠受损窦房结细胞动作电位的APD20、APD50，增大APA，缩短动作电位时程，进而加快细胞自发性搏动频率。
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