Electrogenic ion transport in mammalian colon involves an ammonia-sensitive apical membrane K+ conductance.
Electrogenic ion transport in mammalian colon involves an ammonia-sensitive apical membrane K+ conductance.
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哺乳动物结肠中的生电离子传输涉及对氨敏感的顶膜 K 电导。
DOI：
10.1023/a:1021746717702
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发表时间：
2003
影响因子：
3.1
通讯作者：
Matthews,JeffreyB
中科院分区：
文献类型：
--
作者：
Mayol,JulioM;Alarma-Estrany,Pilar;O'Brien,TimothyC;Song,JaekyungC;Prasad,Madhu;Adame-Navarrete,Yolanda;Fernández-Represa,JesusA;Mun,EdwardC;Matthews,JeffreyB
值得注意的是，在不损害正常上皮功能的情况下，高氨浓度可以存在于结肠腔内。我们研究了腔内氨对天然组织中Cl−分泌的影响。采用剥离的人结肠黏膜和未剥离的大鼠远端结肠。配对样品安装在改良的Ussing室中进行电生理研究。在大鼠结肠远端，根尖氨剂量依赖性阻断福斯克林激活的短路电流，IC50≈5 mM。基底侧NH4Cl效果较差。腔内甲胺（50 mM）、铬醇293 B （10 ~ 50 μM）和Ba2+(5 mM)阻断了camp激活的短路电流，而顶点氯曲霉唑（100 μM）没有作用。在剥离的人结肠粘膜中，管腔而非基底侧NH4Cl （10 mM）和管腔Ba2+(5 mM)抑制福斯克林激活的短路电流。氨可能是结肠水和盐分泌的内源性调节剂。哺乳动物结肠顶端K+通道可能参与camp刺激下Cl -分泌的调控。
It is remarkable that high ammonia concentrations can be present within the colonic lumen without compromising normal epithelial function. We investigated the impact of luminal ammonia on Cl−secretion in native tissue. Stripped human colonic mucosa and unstripped rat distal colon were used. Paired samples were mounted in modified Ussing chambers for electrophysiological studies. In rat distal colon, apical ammonia dose-dependently blocked forskolin-activated short-circuit current with an IC50≈ 5 mM. Basolateral NH4Cl was less effective. Luminal methylamine (50 mM), chromanol 293 B (10–50 μM), and Ba2+(5 mM) blocked cAMP-activated short-circuit current but apical clotrimazole (100 μM) was without effect. In stripped human colonic mucosa, luminal but not basolateral NH4Cl (10 mM) and luminal Ba2+(5 mM) suppressed forskolin-activated short-circuit current. Ammonia may be an endogenous regulator of colonic water and salt secretion. Apical K+channels may be involved in the regulation of cAMP-stimulated Cl−secretion in mammalian colon.