Blokkebak-Poulsen J, Sheikh M I, Jacobsen C
Institute of Medical Biochemistry, University of Aarhus, Denmark.
Biochem J. 1990 Dec 15;272(3):839-42. doi: 10.1042/bj2720839.
The characteristics of 86Rb+ fluxes through conductive channels in basolateral-membrane vesicles isolated from pars recta of rabbit kidney proximal tubule were investigated. In RbCl-, KCl- and NaCl-loaded vesicles a transient and almost equal accumulation of 86Rb+ was observed. The uptakes of 86Rb+ were inhibited to the same extent by 10 mM-BaCl2 in all loadings. The accumulation was driven by an electrical diffusion potential. The 86Rb+ flux was dependent on intravesicular Ca2+. Increasing concentrations of Ca2+ gradually decreased the 86Rb+ uptake. At 10 microM-Ca2+ the radioisotope flux was below 20% of control. The vesicles containing the channel showed very low selectivity among the univalent cations K+, Rb+, Li+, Na+ and choline+.
研究了从兔肾近端小管直部分离的基底外侧膜囊泡中86Rb+通过导电通道的通量特征。在装载RbCl-、KCl-和NaCl的囊泡中,观察到86Rb+的短暂且几乎相等的积累。在所有装载情况下,10 mM BaCl2对86Rb+的摄取抑制程度相同。这种积累是由电扩散电位驱动的。86Rb+通量依赖于囊泡内的Ca2+。Ca2+浓度增加会逐渐降低86Rb+的摄取。在10 microM Ca2+时,放射性同位素通量低于对照的20%。含有该通道的囊泡在单价阳离子K+、Rb+、Li+、Na+和胆碱+之间表现出非常低的选择性。