NaPi-mediated transcellular permeation is the dominant route in intestinal inorganic phosphate absorption in rats
NaPi-mediated transcellular permeation is the dominant route in intestinal inorganic phosphate absorption in rats
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DOI：
10.2133/dmpk.21.217
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发表时间：
2006-01-01
影响因子：
2.1
通讯作者：
Hayashi, Masahiro
中科院分区：
文献类型：
--
作者：
Eto, Nobuaki;Tomita, Mikio;Hayashi, Masahiro
食物中的无机磷酸盐有两种吸收途径，通过刷状缘膜的跨细胞途径和通过紧密连接的细胞旁途径。NaPi是一种钠依赖性无机磷酸盐转运蛋白，在大鼠和人类肠道中表达。然而，NaPi对大鼠肠道中生理浓度无机磷酸盐的总载体介导转运的相对贡献尚不清楚。在这里，我们的特点是无机磷酸盐运输通过大鼠小肠使用电压钳分析，允许通过这两个（transcellular和paracellular）途径的无机磷酸盐渗透diffrenatiation。结果表明，在生理正常的情况下，经粘膜。电位差（约2mV）时，无机磷酸盐通过跨细胞途径的渗透大于通过细胞旁途径的渗透。此外，运输显着降低了磷酰甲酸，钠依赖性磷酸转运蛋白抑制剂的孵育介质中，并在无钠条件下严重抑制。在没有电压钳的情况下获得了类似的结果。总之，这些结果表明，NaPi介导的跨细胞渗透是无机磷酸盐通过小肠吸收的主要途径。
Inorganic phosphate in food is absorbed two ways, the transcellular route via the brush border membrane and the paracellular route via tight junctions. NaPi, a sodium-dependent inorganic phosphate transporter, is expressed in rat and human intestine. However, the relative contribution of NaPi to total carrier-mediated transport of physiological concentrations of inorganic phosphate in rat intestine is not clear. Here, we characterized inorganic phosphate transport across the rat small intestine using a voltage-clamp analysis which allowed the diffrentiation of inorganic phosphate permeation through these two (transcellular and paracellular) routes. Results showed that, under a physiologically normal transmucosal. electrical potential difference (about 2 mV), permeation of inorganic phosphate by the transcellular route was greater than that by the paracellular route. Further, transport was significantly decreased by the addition to the incubation medium of phosphonoformic acid, a sodium-dependent phosphate transporter inhibitor, and severely inhibited under sodium-free conditions. Similar results were obtained without the voltage-clamp. Together, these results suggest that NaPi-mediated transcellular permeation is the dominant route in the absorption of inorganic phosphate across the small intestine.