Ionic permeabilities of rat renal cortical brush-border membrane vesicles.
Ionic permeabilities of rat renal cortical brush-border membrane vesicles.
复制标题
DOI：
10.1152/ajprenal.1987.252.4.f700
复制
发表时间：
1987-04
期刊：
影响因子：
--
通讯作者：
M. Lipkowitz;R. Abramson
中科院分区：
文献类型：
--
作者：
M. Lipkowitz;R. Abramson
一般认为，电解质很容易通过肾皮质刷状缘膜小泡(BBMV)平衡。这一假设被用两种新的方法在自由流动电泳法(FFE)、镁聚集或钙聚集制备的大鼠BBMV中得到验证。用电位灵敏的荧光探针3，3‘-二丙基硫代二碳菁碘[dis-C3-(5)]测定囊泡内KCl和RbcL浓度，以及氯相对于K(GCL/GK)和GNA/GK的电导，并利用Na依赖的[~3H]葡萄糖摄取对膜电位变化的响应来近似计算囊内KCl浓度。这些研究表明，在这三种方法制备的BBMV中，KCl未能达到电化学平衡，尽管在22℃下孵育了很长时间；在所有情况下都保持了显著的内向电解质梯度。用FFE制备的BBMV的囊泡内电解质浓度低于用镁或钙制备的BBMV。GCL/GK在FFE制备的BBMV中最低，在Ca制备的BBMV中最高，GNA/GK在所有制剂中相似。BBMV的表观不通透性在解释需要了解囊泡内电解质精确浓度的研究数据时可能会产生重大影响。
It is generally assumed that electrolytes equilibrate readily across renal cortical brush-border membrane vesicles (BBMV). This assumption was tested by use of two new methods in rat BBMV prepared with free-flow electrophoresis (FFE), Mg aggregation, or Ca aggregation. Intravesicular KCl and RbCl concentrations, as well as the conductance of Cl relative to K (GCl/GK) and GNa/GK were determined with the fluorescent, potential-sensitive probe 3,3'-dipropylthiadicarbocyanine iodide [diS-C3-(5)]; intravesicular KCl concentration was also approximated utilizing the response of Na-dependent [3H]glucose uptake to variations in the membrane potential. These studies demonstrated that KCl fails to attain electrochemical equilibrium in BBMV prepared by the three methods, despite prolonged incubation at 22 degrees C; a significant, inwardly directed electrolyte gradient was sustained in all cases. The intravesicular electrolyte concentration was lower in BBMV prepared with FFE than in those prepared with Mg or Ca. GCl/GK was lowest in BBMV prepared with FFE and highest in those prepared with Ca; GNa/GK was comparable in all preparations. The apparent impermeance of BBMV may impact significantly in interpreting data from studies that require knowledge of the precise concentration of intravesicular electrolytes.