Betancourt O J, Dresel P E
J Pharmacol Exp Ther. 1979 Jul;210(1):64-9.
The interactions of lidocaine (1-5 X 10(-5) M) and calcium ions (1.25-5.0 mM) on electrical characteristics of atrial potentials were determined with standard microelectrode techniques with major reference to the maximum rate of rise of the action potential (Vmax of AP), the time constant of recovery of the rapid sodium carrier (gamma) and repetitive firing due to early extra stimuli (arrhythmia). Lowering Ca caused depolarization and decreased Vmax and gamma; high Ca caused changes in the opposite direction. The relation of gamma to membrane potential was downward concave when membrane potential was changed by Ca but upward concave when equivalent changes in membrane potential were induced by changing the external potassium concentration. Lidocaine (1 X 10(-5) M) had no significant effect at 2.5 mM Ca but significantly decreased the overshoot and Vmax of AP, increased gamma and effective refractory period and was antiarrhythmic at 1.25 mM Ca. These changes were closely similar to the effects of lidocaine (5 X 10(-5) M) at 2.5 mM Ca. The effects of this high concentration were decreased when Ca was changed to 5.0 mM. The effect of lidocaine most clearly predictive of efficacy for the type of arrhythmia was that on Vmax, with changes in gamma in particular not being related to antiarrhythmic activity.
采用标准微电极技术，以动作电位最大上升速率（动作电位Vmax）、快速钠载体恢复时间常数（γ）以及早期额外刺激引起的重复发放（心律失常）为主要参考指标，测定了利多卡因（1 - 5×10⁻⁵M）和钙离子（1.25 - 5.0mM）对心房电位电特性的相互作用。降低钙离子浓度会导致去极化，并降低动作电位Vmax和γ；高钙离子浓度则会引起相反方向的变化。当通过改变钙离子浓度改变膜电位时，γ与膜电位的关系呈向下凹陷，但当通过改变细胞外钾离子浓度诱导膜电位发生等效变化时，γ与膜电位的关系呈向上凹陷。利多卡因（1×10⁻⁵M）在钙离子浓度为2.5mM时无显著影响，但在钙离子浓度为1.25mM时，会显著降低动作电位的超射值和Vmax，增加γ和有效不应期，并具有抗心律失常作用。这些变化与利多卡因（5×10⁻⁵M）在钙离子浓度为2.5mM时的作用非常相似。当钙离子浓度变为5.0mM时，这种高浓度利多卡因的作用会减弱。利多卡因对心律失常类型疗效最具预测性的作用是对动作电位Vmax的影响，特别是γ的变化与抗心律失常活性无关。
