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目的:研究苄基四氢巴马汀(BTHP)对心室肌细胞快激活(I_(Kr))和慢激活(I_(Ks))延迟整流钾电流、内向整流钾电流(I_(Kl))和瞬时外向钾电流(I_(to))的作用.方法:采用全细胞膜片箝技术记录豚鼠及大鼠心室肌细胞钾电流.结果:BTHP在 1-100 μmol/L的范围内以浓度依赖性方式阻滞I_(Kr)和I_(Ks),其中对I_(Kr)的IC_(50)为 13.5 μmol/L(95％可信限:11.2-15.8 μmol/L)而对 I_(Ks)的 IC_(50)则为 9.3 μmol/L(95％可信限:7.8-11.8 μmol/L).BTHP 30μmol/L时可使 I_(Kr)及I_(Kr,tail)分别降低31％±4％和36％±5％(n=6,P<0.01);使I_(Ks)及I_(Ks,tail)分别降低40％±6％和45％±15％(n=7,P<0.01);BTHP 5μmol/L可抑制大鼠心室肌细胞I_(to)电流,使电流幅值降低63％±6％(n=6,P<0.01),BTHP1-100μmol/L以浓度依赖性方式阻滞入I_(to),其 IC_(50)为 3.6 μmol/L(95％可信限:2.9-4.3μmol/L).但BTHP 200 μpmol/L对I_(Kl)基本无影响.结论:BTHP对I_(Kr)、I_(Ks)、I_(to)均有抑制作用,且其阻滞作用呈现出浓度依赖性特征.
AIM: To investigate the effects of benzyltetrahydropalmatine (BTHP) on the delayed rectifier potassium current (I_ (Kl)) and slow activation (I_ (Ks) (I_ (to)) in guinea pig and rat ventricular myocytes.Methods: Whole-cell patch-clamp technique was used to record the potassium current in guinea pig and rat ventricular myocytes.Results: BTHP in the range of 1-100 μmol / L in a concentration-dependent manner I_ (Kr) and I_ (Ks) were blocked with IC_ (50) of 13.5 μmol / L (95% confidence interval: 11.2-15.8 μmol / L) (50%) was 9.3 μmol / L (95% confidence interval: 7.8-11.8 μmol / L), the I Kr and I k decreased by 31% ± 4% and 30 μmol / (Ks) and I (Ks, tail) were reduced by 40% ± 6% and 45% ± 15% (n = 7, P <0.01) BTHP 5μmol / L could inhibit the I-to-current of rat ventricular myocytes, decrease the current amplitude by 63% ± 6% (n = 6, P <0.01), and BTHP1-100μmol / IC_ (50) was 3.6 μmol / L (95% CI: 2.9-4.3 μmol / L), but BTHP 200 μmol / L had no effect on I_ (Kl) .Conclusion: (Kr), I_ (Ks), I_ (to) are inhibited, and Blockade exhibits concentration-dependent features.