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目的观察甘草次酸(glycyrrheticacid,Gta)对大鼠单一心室肌细胞L型钙离子电流(ICa-L)的影响。方法以Langendoff匀速灌流体外大鼠心脏,Ⅰ型胶原酶酶解分离单一大鼠心室肌细胞,将心室肌细胞悬液放入容积为0.2~0.3mL的浴槽内,间隔相同时间分别向浴槽内加入0.1,1.0,10.0μmol·L-1Gta,应用全细胞膜片钳技术记录不同浓度Gta对单一大鼠心室肌细胞ICa-L的影响;保持电位为-30mV、指令电位为-40~+60mV、步阶脉冲为10mV、时程为300ms、刺激频率为0.5Hz的条件下,引出钙离子电流,取指令电位与相对应的钙离子通道电流作用结果制作不同浓度Gta下L型钙离子通道的电流-电压(I-V)关系曲线。结果Gta浓度分别为0.1,1.0,10.0μmo1·L-1时可剂量依赖性地降低ICa-L,分别使ICa-L从加入Gta前的(2.30±0.29)nA降至(1.96±0.34),(1.37±0.24),(0.66±0.20)nA(与加入Gta前比较,均P<0.01);Gta0.1,1.0,10.0μmo1·L-1也可抑制L型钙离子I-V曲线,使I-V曲线上移,但峰值电流不变。结论Gta通过阻滞L型钙通道抑制L型钙离子内流,这种机制可能与Gta抗心律失常作用有关。
Objective To observe the effect of glycyrrhetic acid (Gta) on L-type calcium current (ICa-L) in rat single ventricle myocytes. Methods The rat heart was perfused with Langendoff at a constant rate. Collagenase type I was used to separate and detach single rat ventricular myocytes. The ventricular myocyte suspension was placed in a 0.2-0.3 mL volume bath and added to the bath at the same time intervals. 0.1, 1.0, 10.0 μmol·L -1 Gta, whole-cell patch clamp technique was used to record the effect of different concentration of Gta on ICa-L of single rat ventricular myocytes; maintain potential was -30mV, instruction potential was -40~+60mV, step When the order pulse is 10mV, the time course is 300ms, and the stimulation frequency is 0.5Hz, the calcium ion current is drawn, and the instruction potential and the corresponding calcium ion current effect result in the current of the L-type calcium ion channel under different concentrations of Gta- Voltage (IV) curve. Results The concentration of Gta was 0.1, 1.0 and 10.0 μmol·L-1, respectively, dose-dependently reduced ICa-L, which reduced ICa-L to (1.96±0.34) from (2.30±0.29) nA before Gta addition. (1.37±0.24), (0.66±0.20) nA (P<0.01 compared with before Gta addition); Gta0.1, 1.0, 10.0 μmol1·L-1 also inhibited the L-type calcium ion IV curve, making IV curve Move up but the peak current does not change. Conclusion Gta inhibits L-type calcium influx by blocking L-type calcium channels, and this mechanism may be related to the anti-arrhythmic effects of Gta.