丹参酮Ⅱ-A对豚鼠单个心室肌细胞L-型钙电流的阻断作用

本实验采用全细胞膜片钳技术，观察了丹参酮Ⅱ－Ａ对分离的豚鼠单个心室肌细胞Ｌ－型钙电流及跨膜电位的影响. 使用#FSLangendorff装置和蛋白酶循环消化 (0.2 g·L^-1) 的方法, 获取了70%～80%的横纹清晰, 呈杆状的耐钙心肌细胞. 并使用pCLAMP 5.51微机程序和ELP-7膜片钳放大器记录心肌细胞膜电流和跨膜电位的变化. 丹参酮采用累积加药法, 所有的观察指标均在同一细胞完成. 数据分析采用配对t检验. 当使心肌细胞的保持电压为－40 mV，除极到0 mV，刺激电压的时程为250 ms，频率为0.5 Hz时，10, 20和40 μmol·L^-1的丹参酮Ⅱ－Ａ可使维拉帕米敏感的钙内向电流分别减少35.2％, 57.7％和74.7％ (P<0.05)，并能使动作电位时程亦呈剂量依赖性缩短, 冲洗后两指标均部分恢复. 该药的三种不同浓度，对不同电压最大激活的钙电流的电压依赖曲线均无影响. 结果表明，丹参酮#FSⅡ－Ａ具有类似维拉帕米样Ｌ－型钙通道阻断剂作用，其阻断作用呈非电压依赖性.

Blocking effect of tanshinone Ⅱ-A on L-type Ca2+ current of single ventricular myocyte from guinea pig

The effect of tanshinone II-A (TSN) on L-type Ca²⁺ current of single ventricular myocyte from guinea pig was studied by using whole cell voltage -clamp technique. Langendorff apparatus and method of recirculating digestion with proteinase (0.2 g·L^-1) were also used and, 70% to 80% isolated cells were rod-shaped Ca²⁺-tolerant myocytes with a clear striation. When the membrane potential was held at -40 mV, cell was depolarized to 0 mV for 250 ms at a frequency of 0.5 Hz. TSN 10, 20 and 40 μmol·L^-1 markedly reduced Ca²⁺ inward current by 35.2%, 57.7％ and 74.7％ respectively, without affecting the voltage-dependence of maximal Ca²⁺ current activation. After washing out TSN, the Ca²⁺ current partially recovered. In addition, TSN shortened the action potential duration in a concentration-dependent manner. These data indicate that the blocking effect of TSN on the activation of L-type calcium channels is voltage-independent.