Comparative study of flux of FITC-labeled Dextran 4000 on normal (iso)- and hyper-osmolarity in basal side in caco-2 cell monolayers.
Comparative study of flux of FITC-labeled Dextran 4000 on normal (iso)- and hyper-osmolarity in basal side in caco-2 cell monolayers.
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DOI：
10.2133/dmpk.18.404
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发表时间：
2003-01-01
影响因子：
2.1
通讯作者：
Hayashi, Masahiro
中科院分区：
文献类型：
--
作者：
Ohkubo, Rie;Tomita, Mikio;Hayashi, Masahiro
我们先前已经表明，在正常条件下，异硫氰酸荧光素葡聚糖4000（FD-4）的通量以有利于基底至顶端方向的极化方式跨Caco-2细胞单层转运（即，基底侧等渗溶液）。此外，FD-4转运可能通过一个过程发生，该过程包括一定程度的多糖和转胞吞作用的底物特异性。在本研究中，我们比较了在应力条件下（即，基底侧的高渗透压）与正常条件下的那些（即，基底侧的等渗透压）。高渗可增加基底侧FD-4的外排，但与正常情况相比，内流减少。葡聚糖10，000和秋水仙碱都不能抑制高渗条件下FD-4的外排。S-亚硝基-N-乙酰青霉胺对FD-4外排无抑制作用，硝普钠和亚铁氰化钠对FD-4外排无抑制作用。这些结果共同表明，基底侧的高渗透压加速了Caco-2细胞单层中FD-4通过跨细胞途径的外排，但不通过细胞旁途径。这表明，氰化物，而不是一氧化氮参与功能障碍的FD-4外排系统，无论条件，如正常渗透压或高渗透压。
We have shown previously that the flux of fluorescein isothiocyanate dextran 4000 (FD-4) is transported across the Caco-2 cell monolayers in a polarized fashion favoring the basal to apical direction under normal conditions (i.e., isotonic solution in basal side). Furthermore, FD-4 transport may occur via a process that included a certain degree of substrate specificity for polysaccharide and transcytosis. In the present study, we compared the flux of FD-4 in the basal to apical direction (efflux) and the apical to basal direction (influx) in stress conditions (i.e., hyperosmolarity in basal side) to those in normal conditions (i.e., iso-osmolarity in basal side). The efflux of FD-4 was increased by hyperosmolarity in basal side, but the influx was decreased when compared with normal conditions. Neither dextran 10, 000 nor colchicine inhibited the efflux of FD-4 in hyperosmolarity conditions. The inhibition of efflux of FD-4 was observed not by S-nitroso-N-acetylpenicillamine but by sodium nitroprusside and sodium ferrocyanide. These results collectively suggest that hyperosmolarity in basal side accelerates the efflux of FD-4 across the transcellular route but not across the paracellular route in Caco-2 cell monolayers. And it is indicated that cyanide rather than nitric oxide is involved in dysfunction of the FD-4 efflux system irrespective of conditions such as normal osmolarity or hyperosmolarity.