Champigny G, Lenfant J
Pflugers Arch. 1986 Dec;407(6):684-90. doi: 10.1007/BF00582652.
Voltage clamp experiments were performed on isolated frog sinus venosus trabeculae using the double mannitol gap voltage clamp technique. On hyperpolarization from the holding potential (-30, -50 mV) to various potential levels slow activation of inward current was recorded. Several basic features of this current system resemble those of the current if in mammalian pace-maker tissues. The current activates from a threshold ranging between -50, -70 mV and increases in the inward direction with the negative pulse amplitude. Conductance measurements during current development show a conductance increase. The current is strongly reduced during perfusion with Na-free medium. However, there were several important differences in its properties from those of the if current in other preparations. Ba in concentrations of 0.3-5 mM reduces the amplitude of the inward current in a concentration-dependent manner. Cs in low concentration range (1-10 mM) fails to have any effect on the time dependent current. Cs concentrations higher than 10 mM increase the current amplitude in a dose-dependent manner. The current increase induced by Cs still remains in Na-free solution and is not affected by Cl replacement. These results suggest that Cs may carry inward current. The identity of the ionic mechanism responsible for the observed current is discussed.
采用双甘露醇间隙电压钳技术对分离的蛙窦房小梁进行电压钳实验。从钳制电位（-30、-50 mV）超极化到不同电位水平时，记录到内向电流的缓慢激活。该电流系统的几个基本特征类似于哺乳动物起搏组织中的If电流。电流从-50至-70 mV之间的阈值激活，并随着负向脉冲幅度向内增加。电流产生过程中的电导测量显示电导增加。在用无钠培养基灌注期间，电流大幅降低。然而，其特性与其他制剂中的If电流存在几个重要差异。浓度为0.3-5 mM的钡以浓度依赖的方式降低内向电流的幅度。低浓度范围（1-10 mM）的铯对时间依赖性电流没有任何影响。高于10 mM的铯浓度以剂量依赖的方式增加电流幅度。铯诱导的电流增加在无钠溶液中仍然存在，并且不受氯离子替代的影响。这些结果表明铯可能携带内向电流。讨论了负责观察到的电流的离子机制的身份。
