Sada H, Sada S
Acta Physiol Hung. 1986;68(1):51-9.
The depressant action of four Ca antagonists, including a novel drug, tiapamil, on Ca channels was investigated using a conventional microelectrode technique. "All or none" slow action potentials were recorded in K+-depolarized guinea-pig papillary muscles. Verapamil and diltiazem decreased the amplitude and maximum rate of rise (Vmax) of the slow action potentials at concentrations up to 2 microM. The depressant effect of a novel Ca-antagonist, tiapamil, on the slow action potentials was as marked as that of verapamil and diltiazem. However, prenylamine was less potent than the other 3 drugs. In addition, the action of all drugs on the slow action potentials was enhanced as the frequency of stimulation was increased between 0.0083 and 1 Hz. It was concluded that tiapamil, as verapamil and diltiazem, produced a frequency-dependent blockade of the slow Ca channel.
使用传统微电极技术研究了包括新型药物替帕米在内的四种钙拮抗剂对钙通道的抑制作用。在钾离子去极化的豚鼠乳头肌中记录到了“全或无”的慢动作电位。维拉帕米和地尔硫䓬在浓度高达2微摩尔时可降低慢动作电位的幅度和最大上升速率（Vmax）。新型钙拮抗剂替帕米对慢动作电位的抑制作用与维拉帕米和地尔硫䓬一样显著。然而，普尼拉明的效力低于其他三种药物。此外，当刺激频率在0.0083至1赫兹之间增加时，所有药物对慢动作电位的作用都会增强。得出的结论是，替帕米与维拉帕米和地尔硫䓬一样，对慢钙通道产生频率依赖性阻滞。
