Schiller L R, Santa Ana C A, Morawski S G, Fordtran J S
Department of Internal Medicine, Baylor University Medical Center, Dallas, Texas 75246.
Dig Dis Sci. 1988 Aug;33(8):969-76. doi: 10.1007/BF01535993.
In vitro studies under short-circuited conditions suggest that amiloride, a diuretic agent which is thought to block apical membrane sodium entry, has significant effects on sodium absorption by the human colon. To evaluate this in vivo, we studied the effect of amiloride applied in concentrations of 10(-5) and 10(-4) M on sodium transport and potential difference (PD) in human colon during steady-state perfusion. Net sodium absorption was reduced 25% by amiloride and chloride absorption by 15%; potassium and bicarbonate secretion rates were enhanced. In other studies the colon was divided into a proximal and distal test segment by endoscopic introduction of a collection channel to the descending colon-sigmoid junction. Comparison of tritiated water absorption by the two segments indicated that the distal segment comprised approximately 20% of the total colon surface area. However, the distal test segment only accounted for 5-7% of total sodium, chloride, or water absorption; in contrast, 17-20% of total potassium or bicarbonate secretion occurred there. In the proximal test segment, amiloride reduced net sodium absorption by almost one third from 21.0 to 14.4 mmol/hr (P less than 0.02) but had no significant effect on PD. In the distal test segment, amiloride produced a 25% reduction in mean sodium absorption from 1.2 to 0.9 mmol/hr, but this reduction was not statistically significant; however, potential difference was significantly reduced by 33% (P less than 0.02). These results suggest that most sodium absorption in normal human colon in vivo is mediated by transport processes which are insensitive to these doses of amiloride.(ABSTRACT TRUNCATED AT 250 WORDS)
短路条件下的体外研究表明，氨氯吡脒（一种被认为可阻断顶端膜钠内流的利尿剂）对人结肠的钠吸收有显著影响。为了在体内评估这一作用，我们研究了在稳态灌注期间，浓度为10⁻⁵和10⁻⁴ M的氨氯吡脒对人结肠钠转运和电位差（PD）的影响。氨氯吡脒使钠净吸收减少25%，氯吸收减少15%；钾和碳酸氢盐分泌速率增加。在其他研究中，通过在内镜下将收集通道引入降结肠 - 乙状结肠交界处，将结肠分为近端和远端测试段。两个段氚标记水吸收的比较表明，远端段约占结肠总面积的20%。然而，远端测试段仅占总钠、氯或水吸收的5 - 7%；相比之下，总钾或碳酸氢盐分泌的17 - 20%发生在那里。在近端测试段，氨氯吡脒使钠净吸收从21.0 mmol/hr降至14.4 mmol/hr，减少了近三分之一（P < 0.02），但对PD无显著影响。在远端测试段，氨氯吡脒使平均钠吸收从1.2 mmol/hr降至0.9 mmol/hr，减少了25%，但这一减少无统计学意义；然而，电位差显著降低了33%（P < 0.02）。这些结果表明，在正常人体内结肠中，大多数钠吸收是由对这些剂量氨氯吡脒不敏感的转运过程介导的。（摘要截短于250字）
