Kukushkin N I, Gainullin R Z, Sosunov E A
Pflugers Arch. 1983 Oct;399(2):87-92. doi: 10.1007/BF00663902.
A conventional (single sucrose gap) voltage clamp technique was employed to investigate the rate dependence of ionic currents activated in the plateau range of potential in the rabbit ventricular muscle. A transient outward current of increasing amplitude was observed when the period of rest preceding the test voltage clamp pulse was increased from 0.7-60 s. The action potential duration was short when the transient outward current peak (100-150 ms after the voltage clamp pulse beginning) was high under the studied conditions of stimulation (interbeat intervals 0.7-60 s). The rate dependent transient outward current was small at low levels of depolarization above the resting potential (40 mV), had a maximum at some 90-100 mV and decreased at more positive potentials. This current was sensitive to the simultaneous application of 4-aminopyridine and calcium substitution with strontium in the Tyrode solution. It is suggested that the transient outward current is probably responsible for the changes of the action potential duration in rabbit papillary muscles when the interbeat interval varies from some 0.7-60 s.
采用传统的（单蔗糖间隙）电压钳技术来研究兔心室肌动作电位平台期激活的离子电流的速率依赖性。当测试电压钳脉冲之前的静息期从0.7秒增加到60秒时，观察到一个幅度不断增加的瞬时外向电流。在研究的刺激条件下（心动周期间期为0.7 - 60秒），当瞬时外向电流峰值（在电压钳脉冲开始后100 - 150毫秒）较高时，动作电位时程较短。速率依赖性瞬时外向电流在高于静息电位（40毫伏）的低去极化水平时较小，在约90 - 100毫伏时达到最大值，并在更正的电位时减小。该电流对在台氏液中同时应用4 - 氨基吡啶和用锶替代钙敏感。有人提出，当心动周期间期在约0.7 - 60秒之间变化时，瞬时外向电流可能是兔乳头肌动作电位时程变化的原因。
