Nilius B, Benndorf K, Markwardt F
Pflugers Arch. 1986 Dec;407(6):691-3. doi: 10.1007/BF00582653.
Currents through single Na channels of ventricular cells from adult mouse and guinea pig hearts were studied using the patch clamp technique. Under control conditions the majority of openings is brief and a clustering at the beginning of the depolarizing pulse can be observed. Only between 1 and 8% of the sweeps show long lasting bursts. The bursting may account for a second slow phase of decay of macroscopic currents. In the presence of aconitine in the pipette up to 80% of the sweeps showed bursts underlying the slow inactivation of aconitine modified macroscopic currents. The mean open times are unchanged but the number of openings per sweep is dramatically increased due to aconitine. It is discussed that Na channels may function in different "modes". One mode is characterized by a fast transition into an absorbing state the other one by frequent reopenings ("bursts"). aconitine favours the "bursting" mode.
运用膜片钳技术研究了成年小鼠和豚鼠心室肌细胞单个钠通道的电流。在对照条件下，大多数通道开放时间短暂，去极化脉冲开始时可观察到通道开放的簇集现象。只有1%至8%的扫描显示出持续时间较长的爆发式开放。这种爆发式开放可能是宏观电流衰减的第二个缓慢阶段的原因。当移液管中存在乌头碱时，高达80%的扫描显示出爆发式开放，这是乌头碱修饰的宏观电流缓慢失活的基础。平均开放时间不变，但由于乌头碱的作用，每次扫描的开放次数显著增加。讨论了钠通道可能以不同的“模式”发挥作用。一种模式的特征是快速转变为失活状态，另一种模式的特征是频繁重新开放（“爆发式开放”）。乌头碱有利于“爆发式开放”模式。
