Ionic requirements of proximal tubular sodium transport. III. Selective luminal anion substitution.
Ionic requirements of proximal tubular sodium transport. III. Selective luminal anion substitution.
复制标题
近端肾小管钠转运的离子需求。
DOI：
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发表时间：
1979
影响因子：
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通讯作者：
G. Giebisch
中科院分区：
文献类型：
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作者：
R. Green;J. Bishop;G. Giebisch
采用连续管腔微灌注方法研究了管腔阴离子取代对大鼠肾近曲小管钠和液体吸收的影响。用 25 mM 乙酸盐替代对照林格灌注液中的碳酸氢盐，使净钠重吸收减少 40%；被氯化物取代后，其含量降低了 25%；用甜蜜素替代后，其含量降低了 70%。除氯化林格氏灌注外，在所有情况下，乙酰唑胺的输注均减少了净钠和液体转运。当没有施加氯化物浓度梯度时，添加到灌注液中的氰化物完全抑制液体和钠的移动，但当存在标称36 mM跨上皮氯化物浓度梯度时，仅将液体和溶质移动减少68%。我们从这些观察中得出结论，钠重吸收的被动力可以解释适量的钠转运，低浓度乙酰唑酰胺的作用取决于管腔中碳酸氢根的存在，并且一些阴离子通过减少与钠共转运的渗透阴离子的可用性或通过对钠和/或氯转运系统的直接影响来改变净钠转运。
The effect of substitution of luminal anions on sodium and fluid absorption in rat renal proximal convoluted tubules was studied with continuous luminal microperfusion methods. Substitution of bicarbonate in the control Ringer perfusion fluid by 25 mM acetate reduced net sodium reabsorption by 40%; substitution by chloride reduced it by 25%; and substitution by cyclamate reduced it by 70%. Infusion of acetazolamide reduced net sodium and fluid transport in all cases except chloride-Ringer perfusion. Cyanide added to the perfusion fluid inhibited fluid and sodium movement completely when there was no imposed chloride concentration gradient, but only reduced fluid and solute movement by 68% when a nominal 36 mM transepithelial chloride concentration gradient existed. We conclude from these observations that passive forces for sodium reabsorption can account for a moderate amount of sodium transport, that the effects of acetazolamide in low concentrations are dependent on the presence of bicarbonate in the lumen, and that some anions alter net sodium transport either by reducing the availability of permeant anion for co-transport with sodium or by a direct effect on the sodium and/or chloride transport systems.