失神经支配的青蛙缝匠肌中的钾离子运动。

Potassium movements in denervated frog sartorius muscle.

作者信息

Venosa R A, Kotsias B A

出版信息

Am J Physiol. 1985 Mar;248(3):C219-27. doi: 10.1152/ajpcell.1985.248.3.C217.

DOI:10.1152/ajpcell.1985.248.3.C217

Abstract

The movement of 42K+ across the sarcolemma and the resting membrane potential (VM) of normal and denervated frog sartorius muscle were studied under several experimental conditions in preparations initially equilibrated in 100 mM K+ and 219 mM Cl-. The results can be summarized as follows. In the absence of any driving force on K+, i.e., when the difference between VM and the K+ equilibrium potential (EK) is zero (VM - EK = 0), the K+ conductance (gK) was 368 microseconds . cm-2 in control and 282 microseconds. in denervated muscle. The reduced gK of denervated muscles results from the addition of the opposite changes in the conductances of a Rb+-sensitive inward rectifying pathway (gIR), which decreases, and a Rb+-insensitive linear channel (gL), which increases. Thus in control muscles gK (368 microseconds . cm-2) equals gIR (359 microseconds . cm-2) plus gL (9 microseconds . cm-2), while in denervated muscles gK (282 microseconds . cm-2) equals gIR (198 microsecond . cm-2) plus gL (84 microseconds . cm-2). Denervation significantly reduces the inward rectifying properties of the resting K+ permeability system. In the presence of outward driving forces on K+ (VM - EK greater than 0) of 35-50 mV, the Rb+-sensitive inward rectifier channel appears to close completely in both control and denervated muscles. In the latter, however, the effect was not as well maintained as in the former, suggesting that its closing mechanism might be altered by denervation. No changes were observed during the first 2 wk after denervation.

摘要

在最初平衡于100 mM K⁺和219 mM Cl⁻的制备物中，在几种实验条件下研究了42K⁺跨正常和去神经支配的青蛙缝匠肌肌膜的运动以及静息膜电位（VM）。结果可总结如下。在K⁺没有任何驱动力时，即当VM与K⁺平衡电位（EK）之间的差值为零时（VM - EK = 0），对照肌肉中的K⁺电导（gK）为368微西门子·厘米⁻²，去神经支配肌肉中的为282微西门子·厘米⁻²。去神经支配肌肉的gK降低是由于对Rb⁺敏感的内向整流途径（gIR）的电导发生相反变化（降低）以及对Rb⁺不敏感的线性通道（gL）的电导增加。因此，对照肌肉中gK（368微西门子·厘米⁻²）等于gIR（359微西门子·厘米⁻²）加上gL（9微西门子·厘米⁻²），而去神经支配肌肉中gK（282微西门子·厘米⁻²）等于gIR（198微西门子·厘米⁻²）加上gL（84微西门子·厘米⁻²）。去神经支配显著降低了静息K⁺通透性系统的内向整流特性。在K⁺存在35 - 50 mV的外向驱动力（VM - EK大于0）时，对Rb⁺敏感的内向整流通道在对照和去神经支配的肌肉中似乎都完全关闭。然而，在后者中，这种效应不如前者维持得好，这表明其关闭机制可能因去神经支配而改变。去神经支配后的前2周未观察到变化。