pH-dependent fluoride transport in intestinal brush border membrane vesicles
pH-dependent fluoride transport in intestinal brush border membrane vesicles
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DOI：
10.1016/s0005-2736(98)00064-9
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发表时间：
1998-07-17
影响因子：
3.4
通讯作者：
Whitford, GM
中科院分区：
文献类型：
--
作者：
He, H;Ganapathy, V;Whitford, GM
氟（F）从大鼠胃和膀胱，仓鼠颊囊，和肾小管的几个物种的吸收是pH梯度依赖性的。这些观察结果导致了这样的假设，即F以未解离的酸HF的形式穿过这些上皮细胞。然而，最近的一些报道，提供了证据表明，从大鼠小肠的F吸收是不敏感的内腔pH值，我们在这里报告我们的证据表明，兔小肠刷状缘膜囊泡（BBMV）的F吸收发生迅速，只有在存在一个向内定向的质子梯度的过冲。在质子梯度的情况下，或在存在一个外向的梯度，F的吸收是缓慢的，没有过冲。在一个向内定向的质子梯度的存在下，F摄取部分抑制DIDS和DEP，但不diBAC。PCMBS以剂量反应方式抑制高达83%的F摄取。DiBAC似乎略微降低囊泡内pH，但其他试剂没有影响。当吸收缓冲液中含有氯化物或硝酸盐时，与甘露醇或葡萄糖酸盐对照相比，F吸收被部分抑制。可以得出结论，通过载体介导的过程，这可能涉及F与H+或交换F与OH-的F运输通过兔肠道BBMV发生。DIDS、DEP和PCMBS的抑制作用可能通过影响这种载体介导的转运而发生。(C)1998 Elsevier Science B. V.保留所有权利。
Fluoride (F) absorption from the rat stomach and urinary bladder, hamster cheek pouch, and the renal tubules of several species are pH gradient-dependent. These observations led to the hypothesis that F crosses these epithelia in the form of the undissociated acid, HF. Several recent reports, however, have provided evidence that F absorption from the rat small intestine is insensitive to the lumenal pH, We report here our evidence that F uptake by rabbit intestinal brush border membrane vesicles (BBMV) occurred rapidly and with an overshoot only in the presence of an inward-directed proton gradient. In the absence of a proton gradient or in the presence of an outward-directed gradient, F uptake was slow and without an overshoot. In the presence of an inward-directed proton gradient, F uptake was partially inhibited by DIDS and DEP but not by diBAC. PCMBS inhibited F uptake by up to 83% in a dose-response manner. DiBAC appeared to reduce intravesicular pH slightly but the other reagents had no effect. When the uptake buffer contained chloride or nitrate, F uptake was partially inhibited compared to the mannitol or gluconate controls. It was concluded that F transport across the rabbit intestinal BBMV occurs via a carrier-mediated process which may involve cotransport of F with H+ or exchange of F with OH-. The inhibitory effects of DIDS, DEP and PCMBS may occur by affecting this carrier-mediated transport. (C) 1998 Elsevier Science B.V. All rights reserved.