Kuang Y, Liu T P
Department of Pharmacology, Nanjing Medical College, China.
Zhongguo Yao Li Xue Bao. 1990 May;11(3):225-9.
The rate-dependent block (RDB) of changrolin on the maximal rate of depolarization (Vmax) of action potentials was studied in guinea pig right ventricular papillary muscles. The result was compared with that of class IA (quinidine), IB (mexiletine) and IC (lorcainide) drugs to approach the subclassification of changrolin, by using standard microelectrode techniques with computer. Mexiletine exhibited the fastest response in the onset rate of RDB. Vmax reached 61% of its final value by the second beat during a train of stimuli. In response to a similar train of stimuli, quinidine, lorcainide and changrolin produced exponential falls of Vmax with the constants of -0.143, -0.085 and -0.051 AP-1 (AP = action potentials), respectively. Time constants of recovery for mexiletine, quinidine, lorcainide and changrolin were estimated as 1.58, 9.06, 13.37 and 55.16 s. These suggest that the kinetics of RDB of changrolin are similar to those of IC drugs.
在豚鼠右心室乳头肌中研究了常咯啉对动作电位最大去极化速率（Vmax）的速率依赖性阻滞（RDB）。采用标准微电极技术结合计算机，将结果与IA类（奎尼丁）、IB类（美西律）和IC类（劳卡尼）药物的结果进行比较，以探讨常咯啉的亚分类。美西律在RDB的起效速率方面表现出最快的反应。在一串刺激期间，到第二个搏动时Vmax达到其最终值的61%。对类似的一串刺激，奎尼丁、劳卡尼和常咯啉使Vmax呈指数下降，其常数分别为-0.143、-0.085和-0.051 AP-1（AP =动作电位）。美西律、奎尼丁、劳卡尼和常咯啉的恢复时间常数估计分别为1.58、9.06、13.37和55.16秒。这些表明常咯啉RDB的动力学与IC类药物相似。
