Satoh H, Hashimoto K
Jpn J Pharmacol. 1984 Apr;34(4):411-5. doi: 10.1254/jjp.34.411.
The effects of nicorandil (SG-75) (3-500 micrograms/ml) on the membrane potential and currents of the rabbit sino-atrial node were studied using the voltage clamp technique. Low concentrations of nicorandil (3-10 micrograms/ml) increased the action potential duration (APD) and depolarized the maximum diastolic potential (DMP), but higher concentrations had no such effect and even decreased APD and tended to hyperpolarize MDP. Regardless of these effects, nicorandil decreased the heart rate concentration-dependently. On the current systems of the sino-atrial node, 3 micrograms/ml of nicorandil decreased the outward current (ik), but concentrations of over 10 micrograms/ml increased it. The voltage dependency of the steady-state activation of ik was unchanged. Nicorandil did not affect the inward current activated by hyperpolarization (Ih) and the slow inward current (is). These results suggest that the cardiac effects induced by nicorandil must have been produced by selective change in the conductance of ik.
采用电压钳技术研究了尼可地尔（SG - 75）（3 - 500微克/毫升）对家兔窦房结膜电位和电流的影响。低浓度的尼可地尔（3 - 10微克/毫升）可延长动作电位时程（APD）并使最大舒张电位（DMP）去极化，但较高浓度则无此作用，甚至会缩短APD并使MDP趋于超极化。尽管有这些影响，尼可地尔仍可浓度依赖性地降低心率。在窦房结的电流系统中，3微克/毫升的尼可地尔可降低外向电流（ik），但浓度超过10微克/毫升时则会增加该电流。ik稳态激活的电压依赖性未发生改变。尼可地尔不影响超极化激活的内向电流（Ih）和慢内向电流（is）。这些结果表明，尼可地尔引起的心脏效应必定是由ik电导的选择性变化所致。
