Kojima M
Eur J Pharmacol. 1981 Jan 5;69(1):11-24. doi: 10.1016/0014-2999(81)90597-5.
The effects of disopyramide on the transmembrane action potential in guinea-pig papillary muscles were studied with special reference to the dependence of the effects on the external concentrations of K+ ([K+]0), stimulation rates, and diastolic intervals. Disopyramide, 2 micrometer, prolonged the 90% action potential duration (ADP90) without changing the maximum rate of phase 0 depolarization (Vmax) (class 3 action), whereas disopyramide, 20 micrometer, reduced Vmax, (class 1 action). The class 3 action was prominent in 2.7 and 5.4 mM [K+]0, at 0.25--1 Hz, and so was the class 1 action in 8.1 mM [K+]0, at 2--5 Hz. Disopyramide, 20 micrometer, enhanced the rate-dependent reduction in Vmax only in 8.1 mM [K+]0. Neither concentration of disopyramide altered the recovery kinetics of APD90 in the premature responses in three [K+]0, but slowed that of Vmax only in 8.1 mM [K+]0. These results indicate that the manifestation of class 3 action of disopyramide is favored with low concentrations of the drug, low [K+]0, and low stimulation rates, whereas the reverse is true in the class of the class 1 action.
研究了丙吡胺对豚鼠乳头肌跨膜动作电位的影响，特别参考了这些影响对细胞外钾离子浓度（[K⁺]₀）、刺激频率和舒张间期的依赖性。2微摩尔的丙吡胺延长了90%动作电位时程（ADP90），而不改变0期去极化最大速率（Vmax）（3类作用），而20微摩尔的丙吡胺降低了Vmax（1类作用）。3类作用在[K⁺]₀为2.7和5.4毫摩尔、频率为0.25 - 1赫兹时较为突出，1类作用在[K⁺]₀为8.1毫摩尔、频率为2 - 5赫兹时较为突出。20微摩尔的丙吡胺仅在[K⁺]₀为8.1毫摩尔时增强了Vmax的频率依赖性降低。两种浓度的丙吡胺均未改变三种[K⁺]₀下早搏反应中ADP90的恢复动力学，但仅在[K⁺]₀为8.1毫摩尔时减慢了Vmax的恢复动力学。这些结果表明，丙吡胺的3类作用在低药物浓度、低[K⁺]₀和低刺激频率时更易表现出来，而1类作用则相反。
