Amiloride-sensitive salt and fluid absorption in small intestine of sodium-depleted rats.
Amiloride-sensitive salt and fluid absorption in small intestine of sodium-depleted rats.
复制标题
缺钠大鼠小肠中阿米洛利敏感的盐和液体吸收。
DOI：
10.1152/ajpgi.1985.248.1.g133
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
U. Hopfer
中科院分区：
文献类型：
--
作者：
P. Will;R. Cortright;R. Groseclose;U. Hopfer
Na+耗竭引起的继发性醛固酮增多症与小肠和远端结肠对盐分和液体的吸收增加有关，但与盲肠和近端结肠的吸收无关。因为小肠的这些变化还没有被记录在案，所以这项研究侧重于对这一组织的调节。氯化钠和水的吸收增加在体外表现为短路电流和跨上皮电位的增加，在体内表现为液体吸收的增加和Na+和水的腔含量的减少。例如，钠离子缺乏的大鼠回肠短路电流是去肾上腺大鼠的2倍，是肾上腺完整对照动物的1.3倍。在Na+缺乏的动物中，微摩尔浓度的阿米洛利可抑制24+/-14%的短路电流，而对照组动物的短路电流为1+/-3%。同样，体内Na+缺乏的动物回肠液体吸收率是对照动物的2.3倍。额外的液体吸收对50微米的阿米洛利敏感，而阿米洛利对对照组动物没有影响。此外，缺乏Na+的动物回肠食管壁的Na+含量约为对照组的一半。这些结果表明，矿物皮质激素可以诱导小肠对阿米洛利敏感的钠离子转运体，这种上皮性盐分转运可能成为小肠盐滞留的主要途径。
Secondary hyperaldosteronism produced by Na+ depletion was associated with increases in salt and fluid absorption in both the small intestine and the distal colon but not in the cecum and the proximal colon. Because these changes had not been documented for the small intestine, this study focused on the regulation of this tissue. Increased NaCl and water absorption was expressed in vitro by increases in short-circuit current and transepithelial potential and in vivo by increased fluid absorption and a decreased luminal content of Na+ and water. For example, the short-circuit current in the ileum of Na+-depleted rats was 2-fold that of adrenalectomized and 1.3-fold that of adrenal-intact control animals. The short-circuit current was inhibitable 24 +/- 14% by micromolar concentrations of amiloride in Na+-deficient animals compared with 1 +/- 3% in control animals. Similarly, ileal fluid absorption in vivo was 2.3-fold higher in Na+-deficient relative to control animals. The additional fluid absorption was sensitive to 50 microM amiloride, whereas amiloride had no effect in control animals. Furthermore, the Na+ content of the chyme from the ileum of Na+-deficient animals was about half that of controls. These results suggest that mineralocorticoids can induce the amiloride-sensitive Na+ transporter in the small intestine and that this type of epithelial salt transport can become a major pathway for salt retention by the small intestine.