Transport of butyric acid in vascularly perfused anuran small intestine: importance of pH and anion transport.
Transport of butyric acid in vascularly perfused anuran small intestine: importance of pH and anion transport.
复制标题
丁酸在血管灌注的无尾小肠中的运输：pH 和阴离子运输的重要性。
DOI：
10.1152/ajpgi.1986.250.4.g469
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
Boyd,CA
中科院分区：
文献类型：
--
作者：
Hollander,D;Gerard,EM;Boyd,CA
在离体的、血管灌注的青蛙小肠中研究了丁酸的转运。在管腔丁酸浓度为 5-50 mM 时，吸收是管腔浓度的非线性函数，而吸收与浓度的关系在 0-1,000 µM 时保持线性。调节丁酸转运速率和方向的最重要因素是 pH 值。我们使用单向通量分析来确定在改变管腔或血管室的 pH 值时穿过上皮的净运输。我们发现，当管腔 pH 值从 6.0 增加到 8.0 时，进入门脉循环的丁酸运输量减少了四到五倍。血管灌注液的 pH 值以相同的比例影响丁酸从血管到管腔的转运。丁酸转运的第二个重要调节因子是 4,4'-二异硫氰芪-2,2'-二磺酸 (DIDS) 敏感阴离子转运蛋白。在 pH 7.4 时，以 10(-6) M 添加到管腔中的 DIDS 使丁酸转运减少了约 40%。当将 DIDS 添加到血管灌注液中或在血管到管腔方向测量丁酸转运时，DIDS 也会抑制丁酸转运。我们认为，在近端小肠相对较低的 pH 值下，丁酸变得质子化和亲脂性，并且主要直接通过细胞膜转运。在远端小肠的 pH 值偏碱性时，丁酸呈电离形式，并且由 DIDS 敏感的阴离子转运蛋白进行转运可能占主导地位。
Butyric acid transport was studied in the isolated, vascularly perfused frog small intestine. At luminal butyric acid concentrations of 5-50 mM, absorption was a nonlinear function of the luminal concentration, whereas the relationship of absorption to concentration remained linear at 0-1,000 microM. The most important factor regulating the rate and direction of butyric acid transport was the pH. We used unidirectional flux analysis to determine net transport across the epithelium while the pH of the luminal or vascular compartments was changed. We found a four- to fivefold decrease in butyric acid transport into the portal circulation as the lumen pH was increased from 6.0 to 8.0. The pH of the vascular perfusate influenced the vascular-to-lumen transport of butyric acid in the same proportions. The second important regulatory factor of butyric acid transport was the 4,4'-diisothiocyananostilbene-2,2'-disulfonic acid (DIDS)-sensitive anion transport protein. DIDS added to the lumen at 10(-6) M decreased butyric acid transport by approximately 40% at pH 7.4. DIDS also inhibited butyric acid transport when added to the vascular perfusate or when transport was measured in a vascular-to-lumen direction. We suggest that, at the relatively low pH of the proximal small intestine, butyric acid becomes protonated and lipophilic and is mainly transported directly through the cell membrane. At the more alkaline pH of the distal small intestine butyric acid is in the ionized form and transport by the DIDS-sensitive anion transport protein may predominate.