丹参酮Ⅱ对乳鼠窦房结细胞快激活延迟整流钾电流的作用

Effects of sodium tanshinone ⅡA sulfonate on IKr currents in sinoatrial node cells from neonatal rats

摘要:

目的 研究丹参酮Ⅱ对乳鼠窦房结细胞快激活延迟整流钾电流（IKr）的作用。方法 选择新生24h内Wistar大鼠乳鼠，分离、培养乳鼠窦房结细胞，运用全细胞膜片钳技术记录IKr，采用细胞外灌流的方法应用丹参酮Ⅱ，观察其对IKr电流的影响。结果 30μmol/L丹参酮Ⅱ可以使乳鼠窦房结细胞搏动频率显著加快，从（157.2±10.3）次/min增加至（268.1±12.6）次/min。30μmol/L丹参酮Ⅱ使IKr的尾电流（IKr,tail）电流密度从（54.6±4.7）pA/pF增加至（86.3±8.3）pA/pF（P＜0.01）。在1～100μmol/L范围内，此作用呈浓度依赖性特征，半数有效浓度（EC50）为（29.3±1.02）μmol/L，Hill系数为1.05。门控机制研究发现，该效应与药物增加乳鼠窦房结细胞IKr的激活和失活后恢复有关，而与通道失活关系不大。结论 丹参酮Ⅱ可以增加乳鼠窦房结细胞IKr的电流密度，从而缩短复极时间，增加搏动频率。

Abstract:

Objective To investigate the effects of sodium tanshinoneⅡA sulfonate (STS) on rapidly activating component of delayed rectifier K current (IKr) in sinoatrial node cells (SNCs) from neonatal rats. Methods The SNCs were isolated and cultured from the sinus node tissues derived from neonatal rats (＜24 hours old) by enzymatic dispersion with differential attachment as well as 5’-bromodeoxyufidine (5-BrdU). IKr currents in the STS treated cells were measured by whole-cell configuration with patch-clamp technique. Results The frequency of SNCs beat was significantly increased by 30μmol/L STS, from (157.2±10.3) to (268.1±12.6) times/min. This dose of STS induced the current densities of IKr,tail increased from (54.6±4.7) to (86.3±8.3) pA/pF (n＝10, P＜0.01). IKr,tail was excited by 1 to 100μmol/L STS in a dose-dependent fashion, with a half maximal effective concentration (EC50) of (29.3±1.02)μmol/L and Hill coefficient of 1.05. Investigation of gating mechanism showed that the effect was associated with the increase of STS concentration enhancing the steady-state activation and the recovery of inactivation of IKr,tail currents in SNCs, but hade little effect on the steady-state inactivation of IKr. Conclusion STS improves the densities of IKr, and then shortens repolarization duration and enhances pulse frequency of SNCs.