Kotake H, Saitoh M, Ogino K, Hirai S, Matsuoka S, Hasegawa J, Mashiba H
1st Department of Internal Medicine, Yonago, Japan.
Eur J Pharmacol. 1987 Jul 23;139(3):307-13. doi: 10.1016/0014-2999(87)90588-7.
The effects of cyproheptadine (0.1-10 microM) on the membrane potentials and currents of rabbit sinoatrial node were examined with the double-microelectrode voltage clamp technique. Cyproheptadine reduced the heart rate, maximum rate of depolarization and action potential amplitude. It also decreased the slope of phase 4 depolarization. On the current systems, cyproheptadine decreased the slow inward current (Isi), the time-dependent potassium outward current (Ik) and the hyperpolarization-activated current (Ih). The reduction of Isi was the major effect. Furthermore, Isi was progressively decreased by repetitive membrane depolarization during administration of cyproheptadine, an effect suggestive of frequency-dependent block of Isi. These electrophysiological observations indicate that cyproheptadine has a calcium antagonistic property, and additionally, decreases Ik and Ih in rabbit sinoatrial node.
采用双微电极电压钳技术研究了赛庚啶（0.1 - 10微摩尔）对家兔窦房结膜电位和电流的影响。赛庚啶降低心率、最大去极化速率和动作电位幅度，还降低4期去极化斜率。在电流系统方面，赛庚啶降低慢内向电流（Isi）、时间依赖性钾外向电流（Ik）和超极化激活电流（Ih）。Isi的降低是主要作用。此外，在给予赛庚啶期间，重复膜去极化使Isi逐渐降低，这一效应提示Isi存在频率依赖性阻滞。这些电生理观察结果表明，赛庚啶具有钙拮抗特性，此外，还可降低家兔窦房结的Ik和Ih。
