The use of potential-sensitive cyanine dye for studying ion-dependent electrogenic renal transport of organic solutes. Spectrophotometric measurements.
The use of potential-sensitive cyanine dye for studying ion-dependent electrogenic renal transport of organic solutes. Spectrophotometric measurements.
复制标题
使用电位敏感花青染料研究有机溶质的离子依赖性生电肾转运。
作者：
U. Kragh‐Hansen;K. Jørgensen;M. Sheikh
采用电位敏感染料3,3′-二乙基氧二碳氰碘化剂，研究了兔肾皮质光膜和基底侧膜囊泡对糖、中性氨基酸、单羧酸和二羧酸四种不同类型有机溶质的肾转运。缬霉素诱导的K（+）扩散电位引起染料-膜-囊泡吸收光谱的变化。这些变化与囊泡的去极化和超极化之间存在线性关系。将d-葡萄糖、l-苯丙氨酸、琥珀酸盐或l-乳酸盐添加到光膜囊泡中，在囊外b>囊内Na（+）梯度存在的情况下，导致快速的瞬时去极化。基底侧膜囊泡未观察到d-葡萄糖或l-苯丙氨酸的电致转运。分光光度竞争研究表明，d-半乳糖与d-葡萄糖的电性运输系统相同，而l-苯丙氨酸、琥珀酸盐和l-乳酸盐在光膜囊泡中由不同的系统运输。同时加入d-葡萄糖和l-苯丙氨酸对吸光度的影响是附加的。这些溶质的吸收受到不同渗透性的Na(+)-盐阴离子的影响，其存在顺序为：Cl(-)>SO(4)(2-)>葡萄糖酸盐。在囊外Na（+）梯度存在的情况下，将valinomycin添加到负载K（+）的囊泡中可以增强d-葡萄糖和l-苯丙氨酸的摄取。Gramicidin或valinomycin + nigicin分别减少/消除了Na(+)-或Na(+)+K（+）负载囊泡的电致溶质摄取。这些结果有力地支持了光膜囊泡中d-葡萄糖、l-苯丙氨酸、琥珀酸盐和l-乳酸盐的Na（+）依赖性肾电致转运的存在。
Renal transport of four different categories of organic solutes, namely sugars, neutral amino acids, monocarboxylic acids and dicarboxylic acids, was studied by using the potential-sensitive dye 3,3'-diethyloxadicarbocyanine iodide in purified luminal-membrane and basolateral-membrane vesicles isolated from rabbit kidney cortex. Valinomycin-induced K(+) diffusion potentials resulted in concomitant changes in dye-membrane-vesicle absorption spectra. Linear relationships were obtained between these changes and depolarization and hyperpolarization of the vesicles. Addition of d-glucose, l-phenylalanine, succinate or l-lactate to luminal-membrane vesicles, in the presence of an extravesicular>intravesicular Na(+) gradient, resulted in rapid transient depolarization. With basolateral-membrane vesicles no electrogenic transport of d-glucose or l-phenylalanine was observed. Spectrophotometric competition studies revealed that d-galactose is electrogenically taken up by the same transport system as that for d-glucose, whereas l-phenylalanine, succinate and l-lactate are transported by different systems in luminal-membrane vesicles. The absorbance changes associated with simultaneous addition of d-glucose and l-phenylalanine were additive. The uptake of these solutes was influenced by the presence of Na(+)-salt anions of different permeabilities in the order: Cl(-)>SO(4) (2-)>gluconate. Addition of valinomycin to K(+)-loaded vesicles enhanced uptake of d-glucose and l-phenylalanine in the presence of an extravesicular>intravesicular Na(+) gradient. Gramicidin or valinomycin plus nigericin diminished/abolished electrogenic solute uptake by Na(+)- or Na(+)+K(+)-loaded vesicles respectively. These results strongly support the presence of Na(+)-dependent renal electrogenic transport of d-glucose, l-phenylalanine, succinate and l-lactate in luminal-membrane vesicles.