Curcumin, a multi-ion channel blocker that preferentially blocks late Na+ current, prevents I/R induced arrhythmias

Ionic currents were recorded in a whole-cell mode of voltage-clamp configuration and the APs were recorded in a current-clamp configuration after the GO seal is implemented in voltage-clamp mode. Voltage protocols, pipette solutions and external solutions were designed to record different ionic currents. Fitmaster (v2x32, HEKA Electronic) and Origin8.0 (Originlab, Northampton, MA, USA) were used for measurement, statistical analysis and graphic fitting. The concentration-response curves fitted with a Hill function of Y=Bmax/[1 + (IC50/D) n], where Y represent percentage inhibition of currents, n is the Hill coefficient, Bmax is the maximum inhibitory percentage of currents and D is the Cur concentration. The steady-state (in)activation curves were fitted with Boltzmann function of Y=1/[1 + exp (Vm – V1/2)/k], where Y represents relative currents (I/Imax) of steady-state inactivation and the relative conductance (G/Gmax) of steady-state activation, respectively.V1/2 is half (in)activation potential, Vm and k are depolarization potential and slope factor, respectively. The conductance (G) was calculated by G=I/(Vm-Vrev) with the data in the I-V curves, where Vrev is the reversal potential. The time-dependent recovery curve was fitted with an Exponential function of Y=1 – exp(-t/τ), where Y represents I/Imax and t is the time intervals between two-pulse. The time constant-τ reflects the rate of recovery from inactivation. The current data was normalized (Current divided by capacitance) and expressed as current density. Data was presented as means± SD. Parametric tests included Student’s t-test and one-way repeated ANOVA, which were followed by the Bonferroni test for two groups and multiple comparisons, respectively. P<0.05 was considered significant.

本数据集采用电压钳（voltage-clamp）全细胞模式记录离子电流；在电压钳模式下完成GO封接后，切换至电流钳（current-clamp）模式记录动作电位（Action Potentials, APs）。实验设计了差异化的电压刺激方案、电极内液及灌流外液，以记录各类离子电流。实验采用Fitmaster（v2x32，HEKA电子公司）与Origin8.0（Originlab，美国马萨诸塞州北安普顿市）软件完成数据采集、统计分析及图形拟合。浓度-反应曲线采用希尔函数（Hill function）拟合，公式为Y=Bmax/[1 + (IC50/D)^n]，其中Y代表电流抑制百分比，n为希尔系数，Bmax为电流最大抑制率，D为Cur浓度。稳态（失活/激活）曲线采用玻尔兹曼函数（Boltzmann function）拟合，公式为Y=1/[1 + exp((Vm – V1/2)/k)]，其中Y分别代表稳态失活的相对电流（I/Imax）与稳态激活的相对电导（G/Gmax）；V1/2为半（失活/激活）电位，Vm为去极化电位，k为斜率因子。根据I-V曲线数据，通过公式G=I/(Vm-Vrev)计算电导（G），其中Vrev为反转电位。时间依赖性恢复曲线采用指数函数拟合，公式为Y=1 – exp(-t/τ)，其中Y代表I/Imax，t为双脉冲间的时间间隔；时间常数τ反映了通道从失活状态恢复的速率。电流数据已完成归一化处理（电流值除以膜电容），以电流密度形式呈现；实验数据以平均值±标准差（means±SD）表示。统计分析采用参数检验方法，包括两独立样本t检验与单因素重复测量方差分析（one-way repeated ANOVA），两组间比较及多组比较分别辅以Bonferroni校正；以P<0.05作为差异具有统计学意义的判定标准。