Martin B, Favre H
Pflugers Arch. 1984 Mar;400(3):300-5. doi: 10.1007/BF00581563.
A previously described natriuretic factor (NF) found in urine from man receiving a high salt diet has been postulated to be of hormonal nature. This factor inhibits Na-K ATPase and binds to ouabain receptors. In order to investigate if NF exerts its physiological activity through the Na-K ouabain sensitive pump, its capacity for inhibiting sodium transport has been tested in an in vitro rat colon preparation. Colonic mucosa from rats fed 0.55, 3.55, and 6.55 mmol Na a day were mounted in an Ussing chamber. Inhibition of short-circuit current (SCC) and PD was observed only when NF was added to the serosal side of the membrane and was similar to that observed with ouabain. In rats fed a low or normal salt diet, inhibition of SCC and PD starts after a lag period of 10 min and reaches its maximum inhibition (about 60%) after 90 min. By contrast colonic mucosa from rats receiving a high salt diet exhibits a higher SCC and PD (basal values) and inhibition of the sodium transport starts immediately after addition of NF to the bathing solution. The data demonstrate the similarity of physiological action of ouabain and natriuretic factor on the sodium transport by the colon in vitro. Experiments with rats receiving a high salt diet suggest that by contrast to the kidney, NaCl-dependent cotransport is strongly stimulated by the salt intake in the colon and could be directly inhibited by ouabain or a ouabain-like substance i.e. NF.
在接受高盐饮食的人的尿液中发现的一种先前描述的利钠因子（NF）被推测具有激素性质。该因子抑制钠钾ATP酶并与哇巴因受体结合。为了研究NF是否通过钠钾哇巴因敏感泵发挥其生理活性，已在体外大鼠结肠制剂中测试了其抑制钠转运的能力。将每天喂食0.55、3.55和6.55 mmol钠的大鼠的结肠黏膜安装在Ussing室中。仅当将NF添加到膜的浆膜侧时才观察到短路电流（SCC）和跨膜电位（PD）的抑制，且与用哇巴因观察到的相似。在喂食低盐或正常盐饮食的大鼠中，SCC和PD的抑制在10分钟的延迟期后开始，并在90分钟后达到最大抑制（约60%）。相比之下，接受高盐饮食的大鼠的结肠黏膜表现出更高的SCC和PD（基础值），并且在将NF添加到浴液后立即开始抑制钠转运。数据表明哇巴因和利钠因子在体外对结肠钠转运的生理作用相似。对接受高盐饮食的大鼠的实验表明，与肾脏不同，结肠中的氯化钠依赖性共转运受到盐摄入的强烈刺激，并且可以被哇巴因或类似哇巴因的物质即NF直接抑制。
