积分法:一种药理学中分析电压依赖性瞬时外向钾电流的方法(英文)

Integration: a method for evaluating voltage-dependent transient outward potassium currents in pharmacology

目的 评价一种药理学中分析电压依赖性瞬时外向钾电流 (Ito)的积分方法。方法 Ito的失活相可被 2指数或 3指数方程拟合。原始电流曲线下面积 (AUC)可通过指数方程积分获得。以细胞膜电容标准化后的曲线下面积表示除极化时程中钾离子的净通量 ,作为比较指标。钙调磷酸酶过表达转基因鼠心肌细胞表现Ito下调 ,此数据用于验证Ito的积分分析方法的可靠性。结果 AUC可通过 3指数或2指数方程的积分公式获得 :AUC =A1τ1+A2 τ2 +A3τ3+A0 t -A1τ1e-t/τ1-A2 τ2 e-t/τ2 -A3τ3e-t/τ3或AUC =A1τ1+A2 τ2 +A0 t-A1τ1e-t/τ1-A2 τ2 e-t/τ2 。小鼠心室肌 5 0 %和 90 %动作电位时程分别约为 10ms和 30ms。将Ito0～ 10ms (AUC50 )和 0～ 30ms(AUC90 )的曲线下面积以细胞膜电容进行标准化。野生型鼠心肌细胞的AUC50 和AUC90 明显高于钙调磷酸酶过表达转基因鼠 ,此结果与转基因鼠心室肌细胞动作电位时程延长相一致 ,与前期发表结果一致 (钙调磷酸酶过表达转基因鼠心肌细胞Ito各成分下调 )。结论 积分法是药理学中一种简便准确的分析Ito的方法。

AIM To evaluate the integration method for a nalysis of voltage-dependent Ca 2+-independent transient outward K+ cur rents (I to) in pharmacology. METHODS The inactiva tion phases of I to were best fitted by the sum of two or thr ee exponentials equations. The area u nder the raw current curves (AUC) was obtained by the integration of exponential equations. The AUC normalized to the cell capacitance represented the net K+ charge flow during any depolarized duration and was as the index for comparison. Calcineurin overexpression transgenic (TG) mice showed downregulation of I to. These data were tested by the integration method. RESULTS AUC obtained from three or two exponentials fittings was calculated as: AUC=A 1τ 1+A 2τ 2+A 3τ 3+A 0t-A 1τ 1e - t/τ1-A 2τ 2e -t/τ2-A 3τ 3e -t/τ3 or AUC=A 1τ 1+A 2τ 2+A 0t- A 1τ 1e -t/τ1-A 2τ 2e -t/τ2. The 50% and 90% action potential duration (APD 50, APD 90) in ventricu lar myocytes of mice are about 10 ms and 30 ms, respectively. AUC at 10 ms (AUC 50, AUC of 50% APD) and 30 ms (AUC 90, AUC of 90% APD) in left ventricl e cardiomyocytes of wild type (WT) and TG mice were normalized to the cell capac itance. The normalized AUC 50 and AUC 90 of WT group were significantl y more than those of TG group, which was consistent to the prolongation of APD i n TG mice and the previous published results(downregulation of components of I to in TG mice). CONCLUSION The integration method was an ideal way for analysis of transient outward K+ currents in pharmacology.