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作者用斑片钳技术,在传代培养的大鼠肾上腺髓质瘤无性繁殖细胞(PC12 cell)膜上记录电压依赖性钾离子通道活动。观察到两种超极化时激活的内向离子流,电导为30～60皮西门(PS)及大于100 pS。电导大的通道活动常呈大的闪动样关闭及簇状猝发。电导30～60 pS的钾通道具有如下特征:①明显的电压依赖性。在膜超极化到阈电位水平(30 mV)时,通道开放。同一电压下,单通道电流幅度基本一致,呈正态分布。不同钳位电压下,随着超极化程度增大,电流幅度渐增大。②平均开放时间和开放概率随超极化程度增大而增大,关闭时间则随之而减小。③I-V曲线上显示翻转电位接近K~+的平衡电位。④钾通道阻断剂TEA能阻断该通道。
The authors used a patch clamp technique to record voltage-dependent potassium channel activity on subculturing rat adrenal medullary PC12 cell membranes. Two inward ion fluxes that were activated during hyperpolarization were observed with a conductance of 30-60 picoseconds (PS) and greater than 100 pS. Conductance of large channel activity often showed a big flashing off and cluster-like bursts. Conductance of 30 ~ 60 pS potassium channel has the following characteristics: ① obvious voltage dependence. The channel opens when the membrane is hyperpolarized to a threshold potential level (30 mV). The same voltage, the single-channel current amplitude is basically the same, was normal distribution. Under different clamp voltages, the current amplitude gradually increases with the increase of hyperpolarization. ② The average open time and open probability increase with the degree of hyperpolarization increased, the closure time decreases. ③ I-V curve shows the flip potential close to K ~ + balance potential. ④ potassium channel blocker TEA can block the channel.