Rubashkin A A, Iurinskaia V E, Vereninov A A
Tsitologiia. 2010;52(7):568-73.
The balance of K+, Na+ and Cl- fluxes through cell membrane with the Na+/K+ pump, ion channels and NKCC and NC cotransporters is considered. It is shown that all unidirectional K+, Na+ and Cl- fluxes through cell membrane, permeability coefficients of ion channels and membrane potential can be computed for balanced ion distribution between cell and the medium if K+, Na+ and Cl- concentration in cell water and three fluxes are known: total Cl- flux, total K+ influx and ouabain-inhibitable "pump" component of the K+ influx. Changes in the mortovalent ion balance in lymphoid cells U937 induced to apoptosis by 1 microM staurosporine are analyzed as an example. It is found that the apoptotic shift in ion and water balance in studied cells is caused by a decrease in the pump activity which is accompanied by a decrease in the integral permeability of Na+ channels without significant increase in K+ and Cl- channel permeabilities. Computation shows that only a small part of the total fluxes of K+, Na+ and Cl- accounts for the fluxes via NKCC and NC cotransporters. Therefore, cotransport fluxes can not be studied using inhibitors.
考虑了通过细胞膜的K⁺、Na⁺和Cl⁻通量与Na⁺/K⁺泵、离子通道以及NKCC和NC共转运体之间的平衡。结果表明，如果已知细胞内水的K⁺、Na⁺和Cl⁻浓度以及三种通量：总Cl⁻通量、总K⁺内流和哇巴因抑制的K⁺内流的“泵”成分，那么对于细胞与介质之间平衡的离子分布，可以计算通过细胞膜的所有单向K⁺、Na⁺和Cl⁻通量、离子通道的渗透系数和膜电位。以1微摩尔星形孢菌素诱导淋巴样细胞U937凋亡时单价离子平衡的变化为例进行分析。结果发现，所研究细胞中离子和水平衡的凋亡转变是由泵活性降低引起的，同时伴随着Na⁺通道整体通透性降低，而K⁺和Cl⁻通道通透性没有显著增加。计算表明，K⁺、Na⁺和Cl⁻总通量中只有一小部分是通过NKCC和NC共转运体的通量。因此，不能使用抑制剂来研究共转运通量。
