细胞表面位点之间的协同相互作用：支持细胞电位表面吸附理论的证据。

Cooperative interaction among cell surface sites: evidence in support of the surface adsorption theory of cellular electrical potentials.

作者信息

Ling G N, Fisher A

出版信息

Physiol Chem Phys Med NMR. 1983;15(5):369-78.

Abstract

Resting potentials were studied in frog sartorius muscles equilibrated in Ringer solutions that contained various concentrations of K+. Cells in solutions that contained near-zero K+ showed a rise in potential followed by a slow decline over about 70 hours that paralleled the loss of cellular K+ in exchange for Na+. When these cells were placed in 2.5 mM K+, the re-gain of the potential occurred much more rapidly than the re-gain of cellular K+. Thus, there was no consistent relation between resting potential and concentration of intracellular K+. When cells were immersed in solutions containing 100 mM Na+ and K+ at concentrations of 2.5 mM and greater, there was a semi-logarithmic relation between potential and [K+]ex, in which potential declined as [K+]ex increased. However, when cells were equilibrated in [K+]ex below 2.5 mM, the potential peaked and then declined as [K+]ex decreased. The results are readily explained by the surface adsorption model of the cellular potential, in which the potential is determined simply by the nature of the fixed surface charges that interact with one another in a cooperative manner. The peak and decline of the potential with decreasing [K+]ex below 2.5 mM mirrors the autocooperative shift in the affinity of the surface charged sites from one that favors K+ over Na+ strongly to one that favors K+ over Na+ less strongly.

摘要

在含有不同浓度K⁺的林格氏溶液中平衡的青蛙缝匠肌中研究了静息电位。处于几乎零K⁺溶液中的细胞电位升高，随后在约70小时内缓慢下降，这与细胞K⁺与Na⁺交换导致的K⁺丢失平行。当将这些细胞置于2.5 mM K⁺溶液中时，电位的恢复比细胞K⁺的恢复快得多。因此，静息电位与细胞内K⁺浓度之间没有一致的关系。当细胞浸入含有100 mM Na⁺且K⁺浓度为2.5 mM及更高的溶液中时，电位与[K⁺]ex之间存在半对数关系，其中电位随着[K⁺]ex的增加而下降。然而，当细胞在[K⁺]ex低于2.5 mM的溶液中平衡时，电位先达到峰值，然后随着[K⁺]ex的降低而下降。这些结果很容易用细胞电位的表面吸附模型来解释，在该模型中，电位仅由以协同方式相互作用的固定表面电荷的性质决定。随着[K⁺]ex在2.5 mM以下降低时电位的峰值和下降反映了表面带电位点亲和力的自协同转变，从强烈倾向于K⁺而非Na⁺的状态转变为对K⁺而非Na⁺的倾向较弱的状态。