Active ion transport pathways in the bovine retinal pigment epithelium.
Active ion transport pathways in the bovine retinal pigment epithelium.
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牛视网膜色素上皮中的活性离子转运途径。
DOI：
10.1113/jphysiol.1990.sp018067
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
Edelman,JL
中科院分区：
文献类型：
--
作者：
Miller,SS;Edelman,JL
1. 放射性示踪剂通量测量表明，在眼睛被摘除并从眼睛中取出组织后，活性离子在离体牛视网膜色素上皮 (RPE)-脉络膜制剂上的传输可以维持数小时。 2. 研究表明，86Rb 示踪通量可用于监测牛蛙 RPE 上的钾 (K+) 转运。在牛 RPE 中，86Rb (K+) 净吸收为零。顶端钡 (Ba2+) 将活性 K+ 吸收从零提高到大约 0.3 mu 当量 cm-2 h-1。 Ba2(+) 诱导的活性 K+ 吸收增加被根尖浴中的哇巴因或布美他尼抑制。 3. 在用碳酸氢盐和 CO2 缓冲的对照林格溶液中，RPE-脉络膜以大约 0.5 mu 当量 cm-2 h-1 的速率主动吸收氯离子 (Cl-)。相比之下，钠 (Na+) 的分泌速度约为 0.5 mu equiv cm-2 h-1。顶端布美他尼抑制氯离子吸收，顶端哇巴因抑制Na+分泌。这些药物只有当放置在浸泡组织顶端或视网膜侧的溶液中时才有效。 4. 净氯吸收需要基底外侧膜的排出机制。基础浴中的 DIDS（4,4'-二异硫氰基芪-2,2'-二磺酸）完全抑制不含碳酸氢盐的林格溶液中的净 Cl-吸收。 5. 这些实验表明，氯离子转运途径至少包含两个组成部分：（1）顶膜处的布美他尼敏感摄取机制； (2) 基底外侧膜的外排机制被 DIDS 阻断。 6. 确定了三种顶膜机制，可以帮助调节分隔远端视网膜和 RPE 顶膜的视网膜下或细胞外空间中的 [K+]o。它们是：（1）哇巴因敏感的Na(+)-K+泵； (2)布美他尼敏感机制，推定的Na(+)-K(+)-Cl-协同转运蛋白； (3) 钡敏感的 K+ 通道，将 Na(+)-K+ 泵和协同转运蛋白主动吸收的大部分或全部钾再循环到顶端浴。 7. 这些数据表明，体内发生的光诱导视网膜下钾的变化可以激活氯离子转运途径，并有助于在明暗转换期间调节 RPE 细胞内 Cl-。
1. Radioactive tracer flux measurements demonstrate that active ion transport across the isolated bovine retinal pigment epithelium (RPE)‐choroid preparation can be maintained for hours after the eye is enucleated and the tissue removed from the eye. 2. It has been shown that 86Rb tracer fluxes can be used to monitor potassium (K+) transport across bull‐frog RPE. In bovine RPE, net 86Rb (K+) absorption is zero. Apical barium (Ba2+) elevated active K+ absorption from zero to approximately 0.3 mu equiv cm‐2 h‐1. This Ba2(+)‐induced increase in active K+ absorption was inhibited either by ouabain or bumetanide in the apical bath. 3. In control Ringer solution, buffered with bicarbonate and CO2, the RPE‐choroid actively absorbs chloride (Cl‐) at a rate of approximately 0.5 mu equiv cm‐2 h‐1. In contrast, sodium (Na+) is secreted at a rate of approximately 0.5 mu equiv cm‐2 h‐1. Chloride absorption was inhibited by apical bumetanide, and Na+ secretion was inhibited by apical ouabain. These drugs were only effective when placed in the solution bathing the apical or retinal side of the tissue. 4. Net Cl‐ absorption requires an exit mechanism at the basolateral membrane. DIDS (4,4'‐diisothiocyanostilbene‐2,2'‐disulphonic acid) in the basal bath completely inhibited net Cl‐ absorption in bicarbonate‐free Ringer solution. 5. These experiments show that the chloride transport pathway contains at least two components: (1) a bumetanide‐sensitive uptake mechanism at the apical membrane; and (2) an efflux mechanism at the basolateral membrane that is blocked by DIDS. 6. Three apical membrane mechanisms were identified that could help modulate [K+]o in the subretinal or extracellular space that separates the distal retina and the RPE apical membrane. They are: (1) an ouabain‐sensitive Na(+)‐K+ pump; (2) a bumetanide‐sensitive mechanism, the putative Na(+)‐K(+)‐Cl‐ co‐transporter; (3) a barium‐sensitive K+ channel that recycles, to the apical bath, most or all of the potassium that is actively taken up by the Na(+)‐K+ pump and the co‐transporter. 7. These data suggest that light‐induced alterations in subretinal potassium that occur in vivo can activate the chloride transport pathway and help modulate RPE intracellular Cl‐ during transitions between the light and dark.
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影响因子：
4.4
作者：
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影响因子：
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DOI：
10.1016/0278-4327(85)90004-5
发表时间：
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期刊：
Progress in Retinal Research
影响因子：
--
作者：
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影响因子：
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作者：
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DOI：
10.1152/ajpcell.1983.245.5.c388
发表时间：
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期刊：
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影响因子：
--
作者：
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通讯作者：
Highland,E