电压依赖性钾离子通量及伞藻中动作电位的意义。

Voltage dependent potassium fluxes and the significance of action potentials in Acetabularia.

作者信息

Mummert H, Gradmann D

出版信息

Biochim Biophys Acta. 1976 Sep 7;443(3):443-50. doi: 10.1016/0005-2736(76)90464-8.

Abstract

Membrane potential, Vm, and K+ (86Rb+) fluxes have been measured simultaneously on individual cells of Acetabularia mediterranea. During resting state (resting potential approx. -170 mV) the K+ influx amounts to 0.24-0.6 pmol-cm-2-s-1 and the K+ efflux to 0.2-1.5 pmol-cm-2s-1. According to the K+ concentrations inside and outside the cell (40:1) the voltage dependent K+ flux (zero at Vm = EK = -90 mV) is stimulated approx. 40-fold for Vm more positive than EK. It is calculated that during one action potential (temporary depolarization to Vm more positive than EK) a cell looses the same amount of K+, which leaks in during 10-20 min in the resting state (Vm = -170 mV). Since action potentials occur spontaneously in Acetabularia, they are therefore suggested to have a significant function for the K+ balance of this alga.

摘要

在地中海伞藻的单个细胞上同时测量了膜电位（Vm）和钾离子（86Rb⁺）通量。在静息状态下（静息电位约为 -170 mV），钾离子内流为0.24 - 0.6 pmol·cm⁻²·s⁻¹，钾离子外流为0.2 - 1.5 pmol·cm⁻²·s⁻¹。根据细胞内外的钾离子浓度（40:1），电压依赖性钾离子通量（在Vm = EK = -90 mV时为零）在Vm比EK更正时会被刺激约40倍。据计算，在一次动作电位期间（暂时去极化至Vm比EK更正），细胞损失的钾离子量与在静息状态下（Vm = -170 mV）10 - 20分钟内泄漏进来的钾离子量相同。由于在地中海伞藻中动作电位是自发发生的，因此它们被认为对这种藻类的钾离子平衡具有重要作用。