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目的:研究RP58866对于豚鼠或犬分离心室肌细胞I_K,I_(to),和I_(Kl)的影响。方法:采用全细胞膜片箝技术。结果:在-100 mV时,RP58866以浓度依赖方式明显减少了豚鼠心室肌细胞I_(kl),其IC_(50)为(3.4±0.8)μmol·L~(-1)(n=6)。在犬心室肌细胞,RP58866可明显抑制I_(to),其IC_(50)为(2.3±0.5)μmol·L~(-1)。RP58866 100μmol·L~(-1)阻断豚鼠的心室肌细胞I_K,在+40mv时使I_(Kstep)减少(58±13)％,其IC_(50)为(7.5±0.8)μmol·L~(-1),I_(Ktail)减少(86±17)％,其IC_(50)为(3.5±0.9)μmol·L~(-1)。尾电流分析表明,RP58866对I_(Kr)和I_(Ks)均有阻断作用。结论:RP58866对心肌细胞的I_(Kl)和I_(to),I_K均有抑制作用,而不是一种特殊的I_(Kl)抑制剂。
Objective: To study the effect of RP58866 on I_K, I_ (to) and I_ (Kl) in guinea pig or canine isolated ventricular myocytes. Methods: Whole-cell patch clamp technique was used. RESULTS: At -100 mV, RP58866 significantly reduced the I_ (kl) of guinea pig ventricular myocytes in a concentration-dependent manner with an IC50 of (3.4 ± 0.8) μmol·L -1 (n = 6). In canine ventricular myocytes, RP58866 significantly inhibited I to (IC50) of (2.3 ± 0.5) μmol·L -1. RP58866 (100μmol·L -1) blocked the I_K of guinea pig ventricular myocytes and decreased the I_ (Kstep) to (58 ± 13)% at + 40mv with IC 50 of (7.5 ± 0.8) μmol·L ~ (-1) and I (Ktail) decreased by (86 ± 17)%, and the IC 50 value was (3.5 ± 0.9) μmol·L -1. Tail current analysis showed that RP58866 blocked both I_ (Kr) and I_ (Ks). CONCLUSION: RP58866 inhibits I_ (Kl), I_ (to) and I_K of cardiomyocytes, but not a specific I_ (Kl) inhibitor.