Epithelial Na channels and short-term renal response to salt deprivation.
Epithelial Na channels and short-term renal response to salt deprivation.
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上皮钠通道和短期肾脏对缺盐的反应。
DOI：
10.1152/ajprenal.00379.2001
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
Palmer,LawrenceG
中科院分区：
文献类型：
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作者：
Frindt,Gustavo;McNair,Tiffany;Dahlmann,Anke;Jacobs-Palmer,Emily;Palmer,LawrenceG
为了测试上皮Na通道在肾Na排泄的日常调节中的作用，通过渗透微泵向大鼠输注Na通道阻滞剂阿米洛利，使远端肾单位管腔中的药物浓度达到2-5 μM。每日钠排泄率保持不变，尽管阿米洛利治疗的动物倾向于在下午排泄更多的钠，而在傍晚比对照组少。当给予大鼠低钠饮食时，阿米洛利治疗组的钠排泄率在4小时内升高，并在至少48小时内保持高于对照组。肾上腺切除的动物对低钠饮食的反应相似。与此相反，大鼠输注聚噻嗪的速率，旨在抑制氯化钠运输在远端小管能够保存钠以及控制。注射醛固酮（2 μg/100 g体重）后1小时，对照组动物的钠排泄减少。阿米洛利处理的大鼠中，这种作用基本上被消除。结果的定量分析的基础上，我们得出结论，盐皮质激素的阿米洛利敏感性通道的激活占50-80%的立即钠尿反应的肾脏减少钠摄入量。此外，通道是必要的，以达到最低的钠排泄率在更慢性的钠剥夺。
To test the role of epithelial Na channels in the day-to-day regulation of renal Na excretion, rats were infused via osmotic minipumps with the Na channel blocker amiloride at rates that achieved drug concentrations of 2–5 μM in the lumen of the distal nephron. Daily Na excretion rates were unchanged, although amiloride-treated animals tended to excrete more Na in the afternoon and less in the late evening than controls. When the rats were given a low-Na diet, Na excretion rates were elevated in the amiloride-treated group within 4 h and remained higher than controls for at least 48 h. Adrenalectomized animals responded similarly to the low-Na diet. In contrast, rats infused with polythiazide at rates designed to inhibit NaCl transport in the distal tubule were able to conserve Na as well as did the controls. Injection of aldosterone (2 μg/100 g body wt) decreased Na excretion in control animals after a 1-h delay. This effect was largely abolished in amiloride-treated rats. On the basis of quantitative analysis of the results, we conclude that activation of amiloride-sensitive channels by mineralocorticoids accounts for 50–80% of the immediate natriuretic response of the kidney to a reduction in Na intake. Furthermore, the channels are necessary to achieve minimal rates of Na excretion during more chronic Na deprivation.