论文部分内容阅读
用片膜钳技术,在大鼠肾上腺髓质瘤无性繁殖细胞(PC12细胞)膜记录电压依赖性单钾离子通道活动:在细胞贴附式下去极化电流可激活一个电导为35～55皮西门(pS)的外向钾离子单通道。通道开放呈爆发型和快速闪动型,平均开放时间在0.5～20ms范围,其潜伏期随去极化程度增大而略变小。由撕开的膜片测得的翻转电位表明此通道选择性地让钾离于通过。通道在低钙(10 nmol/L自由钙离子)溶液中开放,增高胞浆侧钙离于浓度对通道开放无明显影响。20mmol/L四乙铵(TEA)可阻断该通道。在200ms的去极化脉冲中通道开放时间所占比例随去极化程度增大而增大,每20～30mV电位可使开放比率增高e(2.73)倍。在7～25秒长的去极化维持电位中,通道进入然后退出一个长时间的失活状态。以上结果表明,这类通道属于延时整流型钾通道。
Membrane patch clamp technique was used to record voltage-dependent monopotassium channel activity in rat adrenal medullary ameloblast (PC12 cells) membranes: depolarizing current flow in cells adhering to a conductivity of 35-55 picoseconds (pS) outgoing potassium ion single channel. The opening of the channel was explosive and rapid flashing, the average open time was in the range of 0.5-20 ms, and its latency slightly decreased with the degree of depolarization increasing. The tipping potential, as measured by the torn membrane, indicates that this channel selectively allows potassium to pass through. Channels in low calcium (10 nmol / L free calcium ions) solution open, increased cytoplasmic calcium concentration on the opening of the channel had no significant effect. 20mmol / L tetraethylammonium (TEA) can block the channel. The proportion of open time of the channel in 200ms depolarization pulse increased with the degree of depolarization, and the open ratio increased by e (2.73) times every 20 ~ 30mV potential. In a depolarization holding potential of 7-25 seconds long, the channel enters and then exits for a long period of inactivation. The above results show that these channels belong to the delayed rectifier potassium channel.