Groves C E, Morales M N
Department of Physiological Sciences, University of Florida, College of Veterinary Medicine, Gainesville, Florida 32611-0885, USA.
J Pharmacol Exp Ther. 1999 Nov;291(2):555-61.
The interaction of the cysteine conjugate S-(1-chloro-1,2,2, -trifluoroethyl)-L-cysteine (CTFC) with organic anion and amino acid transport in the basolateral and apical membranes was examined with rabbit renal proximal tubule suspensions and primary cultures of rabbit renal proximal tubule cells. The apparent K(i) for CTFC inhibition of the 1-min uptake of [(3)H]p-aminohippurate in tubule suspensions was 105+/-3 microM and suggests that CTFC interacts with basolateral organic anion transport. Also, the addition of 1 mM CTFC decreased the secretion and intracellular accumulation of fluorescein by approximately 70 to 75%. The addition of 1 mM CTFC to the apical compartment decreased the reabsorption and intracellular accumulation of the amino acid [(3)H]phenylalanine by approximately 60 to 70%. Similar to CTFC, saturating concentrations of the organic anion [(3)H]p-aminohippurate and the amino acid phenylalanine reduced by approximately 75% fluorescein secretion and [(3)H]phenylalanine reabsorption, respectively, by approximately 60 to 70%. Thus, the cysteine conjugate CTFC appears to be a potent inhibitor of basolateral organic anion and apical amino acid transepithelial transport. In contrast to its effects on apical phenylalanine uptake, CTFC had no effect on the basal uptake of [(3)H]phenylalanine by primary cultures. The presence of CTFC in the external bath did trans-stimulate the efflux of fluorescein and [(3)H]phenylalanine across the basal and apical membrane in tubule suspensions or primary cultures, respectively, grown on plastic. Collectively, these data demonstrate that CTFC interacts with, and is transported by, two anatomically and functionally distinct transporters, the basolateral organic anion and apical neutral amino acid pathways, in the rabbit renal proximal tubule cell.
利用兔肾近端小管悬浮液和兔肾近端小管细胞原代培养物，研究了半胱氨酸共轭物S-(1-氯-1,2,2-三氟乙基)-L-半胱氨酸（CTFC）与基底外侧膜和顶端膜中有机阴离子及氨基酸转运的相互作用。CTFC抑制小管悬浮液中[(3)H]对氨基马尿酸1分钟摄取的表观K(i)为105±3 microM，提示CTFC与基底外侧有机阴离子转运相互作用。此外，添加1 mM CTFC可使荧光素的分泌和细胞内蓄积减少约70%至75%。向顶端隔室添加1 mM CTFC可使氨基酸[(3)H]苯丙氨酸的重吸收和细胞内蓄积减少约60%至70%。与CTFC相似，有机阴离子[(3)H]对氨基马尿酸和氨基酸苯丙氨酸的饱和浓度分别使荧光素分泌和[(3)H]苯丙氨酸重吸收减少约75%和约60%至70%。因此，半胱氨酸共轭物CTFC似乎是基底外侧有机阴离子和顶端氨基酸跨上皮转运的有效抑制剂。与对顶端苯丙氨酸摄取的影响相反，CTFC对原代培养物中[(3)H]苯丙氨酸的基底摄取没有影响。外部浴液中CTFC的存在确实分别反刺激了在塑料上生长的小管悬浮液或原代培养物中荧光素和[(3)H]苯丙氨酸跨基底膜和顶端膜的外流。总体而言，这些数据表明CTFC与兔肾近端小管细胞中两种在解剖学和功能上不同的转运体相互作用并由其转运，即基底外侧有机阴离子途径和顶端中性氨基酸途径。
