海葵素对大鼠和豚鼠心室肌细胞钾电流的影响

  目的 研究海葵素 -Q （ AP-Q ）对心室肌细胞钾电流的作用。 方法 采用酶解法制备豚鼠和大鼠单个心室肌单细胞，应用全细胞膜片钳记录方法记录 心室肌细胞钾电流（ <> I _to ， <> I _K 和 <> I _K1 ）。 结果 AP-Q 3 ~ 100 nmol L^-1 浓度依赖性地阻滞 <> I _to ， EC₅₀ 分别为 10.5 nmol L^-1 ，去极化至 +50 mV 时， AP-Q 10 nmol L^-1 使 <> I _to 从给药前的（ 13.3 ± 3.4 ） pA pF^-1 升至（ 19.46 ± 4.3 ） pA pF^-1 。 AP-Q 0.1~100 nmol L^-1 浓度依赖性地增大 <> I _K 和尾电流 (<>I_{K tail} ) ， EC₅₀ 分别为 4.7 和 5.0 nmol L^-1 。 AP-Q 1 pmol L^-1~100 nmol L^-1 浓度依赖性地增大 <> I _K1 ， EC₅₀ 值为 0.2 nmol L^-1 。 结论 AP-Q 增大 <> I _K ， <> I _to 和 <> I _K1 的作用可能是其缩短 APD ，增大 RP 的原因。

Effects of Sea Anemone Toxin Anthopleurin-Q on Potassium Currents in Rats and Guinea Pig Ventricular Myocytes

OBJECTIVE To study the effects of Sea Anemone Toxin Anthopleurin-Q (AP-Q) on potassium currents of rats and guinea pig ventricular myocytes. METHODS the ventricular cells of guinea pigs and SD rats were obtained by enzymatic dissociation method. Whole cell patch clamp technique was used to record potassium currents，including transient outward potassium currents(Ito)，delayed rectifier potassium current (IK) and inward rectifier potassium current (IK1). RESULTS AP-Q 3-100 nmol L-1 increased Ito in rat ventricular myocytes in a concentration dependent，with EC50 values of 12.7 nmol L-1. At +50 mV of test potential，it was increased from （13.3 ± 3.4）pA pF-1 to（19.46±4.3）pA pF-1 by AP-Q 10 nmol L-1. AP-Q 0.1-100 nmol L-1increased IK and the tail current( IK tail ) concentration-dependent. The EC50 values were 4.7 and 5.0 nmol L-1，respectively. AP-Q 1 pmol L-1-100 nmol L-1 increased IK1 concentration-dependently，with an EC50 of 0.2 nmol L-1. CONCLUSION augmented effect of AP-Q on Ito，IK and IK1 maybe explain partly its effects on shorting APD and increasing absolute value of RP.