Binder H J, Mehta P
Department of Internal Medicine, Yale University, New Haven, Connecticut.
Gastroenterology. 1989 Apr;96(4):989-96. doi: 10.1016/0016-5085(89)91614-4.
Studies were performed to determine the mechanism by which short-chain fatty acids increase colonic Na and Cl absorption by determining unidirectional 22Na and 36Cl fluxes across isolated stripped mucosa from the rat distal colon under voltage clamp conditions. Mucosal butyrate (25 mM, in the absence of bicarbonate) significantly enhanced both net Na and net Cl absorption by 7.0 +/- 1.3 and 6.9 +/- 1.0 microEq/h.cm2, respectively, without increasing the short-circuit current. Net Na and Cl absorption in butyrate-Ringer's solution and HCO3-Ringer's solution were identical. Butyrate stimulation of Na (and Cl) absorption was Cl-dependent and prevented by 1 mM mucosal amiloride, an inhibitor of Na-H exchange, but was HCO3-independent and not inhibited by acetazolamide, a carbonic anhydrase inhibitor. In contrast, bicarbonate-stimulated Na (and Cl) absorption was also Cl-dependent and amiloride-sensitive, but was significantly inhibited by acetazolamide. The effect of mucosal butyrate on net Na and Cl absorption was substantially greater than serosal butyrate, which in the presence of bicarbonate did not alter ion transport. The stimulation of Na and Cl absorption by mucosal butyrate was significantly greater than by propionate and acetate, whereas mucosal formate did not alter Na transport. The results of this study permit the following model: short-chain fatty acid stimulation of active Na and Cl absorption involves uptake of the nonionized form of butyrate and the coupling of Na-H and Cl-butyrate exchanges.
通过在电压钳制条件下测定22Na和36Cl跨大鼠远端结肠分离的剥脱黏膜的单向通量，进行了多项研究以确定短链脂肪酸增加结肠钠和氯吸收的机制。黏膜丁酸（25 mM，无碳酸氢盐）分别显著增强净钠和净氯吸收，增幅分别为7.0±1.3和6.9±1.0微当量/小时·平方厘米，且不增加短路电流。丁酸林格液和碳酸氢盐林格液中的净钠和氯吸收相同。丁酸对钠（和氯）吸收的刺激依赖于氯，且被1 mM黏膜氨氯吡脒（一种钠-氢交换抑制剂）所阻断，但不依赖于碳酸氢盐，也不被碳酸酐酶抑制剂乙酰唑胺所抑制。相比之下，碳酸氢盐刺激的钠（和氯）吸收也依赖于氯且对氨氯吡脒敏感，但被乙酰唑胺显著抑制。黏膜丁酸对净钠和氯吸收的作用明显大于浆膜丁酸，在存在碳酸氢盐的情况下，浆膜丁酸不会改变离子转运。黏膜丁酸对钠和氯吸收的刺激明显大于丙酸和乙酸，而黏膜甲酸不会改变钠转运。本研究结果支持以下模型：短链脂肪酸对钠和氯主动吸收的刺激涉及丁酸非离子化形式的摄取以及钠-氢和氯-丁酸交换的偶联。
