Stoeckel H, Takeda K
Institut de Biologie Moléculaire des Plantes-CNRS UPR406, Strasbourg, France.
J Membr Biol. 1993 Feb;131(3):179-92. doi: 10.1007/BF02260107.
Plasmalemmal ionic currents from excitable motor cells of the primary pulvinus of Mimosa pudica were investigated by patch-clamp techniques. In almost all of the enzymatically isolated protoplasts, a delayed rectifier potassium current was activated by depolarization, while no currents were detected upon hyperpolarization. This sustained outward current was reversibly blocked by Ba and TEA and serves to repolarize the membrane potential. Outward single channel currents that very likely underly the macroscopic outward potassium current had an elementary conductance of approximately 20 pS. In addition, in a few protoplasts held at hyperpolarized potentials, depolarization-activated transient inward currents were observed, and under current clamp, action potential-like responses were triggered by depolarizing current injections or by mechanical perturbations. The activation characteristics of both inward currents and spikes showed striking similarities compared to those of action potentials in situ.
采用膜片钳技术研究了含羞草初级叶枕可兴奋运动细胞的质膜离子电流。在几乎所有酶解分离的原生质体中，去极化激活延迟整流钾电流，而超极化时未检测到电流。这种持续的外向电流被钡和四乙铵可逆性阻断，用于使膜电位复极化。构成宏观外向钾电流基础的外向单通道电流的基本电导约为20 pS。此外，在少数保持在超极化电位的原生质体中，观察到去极化激活的瞬时内向电流，在电流钳模式下，去极化电流注入或机械扰动可触发动作电位样反应。内向电流和尖峰的激活特性与原位动作电位相比具有显著相似性。
