Renal bicarbonate reabsorption in the rat. I. Effects of hypokalemia and carbonic anhydrase.
Renal bicarbonate reabsorption in the rat. I. Effects of hypokalemia and carbonic anhydrase.
复制标题
大鼠肾碳酸氢盐重吸收。
DOI：
10.1172/jci112748
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
Giebisch,G
中科院分区：
文献类型：
--
作者：
Capasso,G;Kinne,R;Malnic,G;Giebisch,G
在大鼠浅表近端和远端小管上进行自由流动显微穿刺研究，以评估不同肾单位段在碳酸氢盐转运中的参与。特别强调了远端小管的作用，以及用于定量重碳酸盐重吸收的微量热法。实验进行了控制条件下，在饮食中的钾撤退，并在急性静脉注射碳酸酐酶。我们观察到在正常酸碱条件下碳酸氢盐的净重吸收非常显著，这可以通过在存在剧烈液体吸收的情况下维持显著的碳酸氢盐浓度梯度来证明。远端重吸收持续在低钾血症，甚至更陡峭的跨上皮浓度梯度的碳酸氢盐维持。增强净重吸收碳酸氢盐后，急性静脉注射碳酸酐酶，但仅限于肾单位之间的晚期近端和早期远端小管段。后一观察结果与近端直小管（S3段）、Henle氏粗升支和/或早期远端小管的pH沿着不平衡一致。
Free-flow micropuncture studies were carried out on superficial rat proximal and distal tubules to assess the participation of different nephron segments in bicarbonate transport. Particular emphasis was placed on the role of the distal tubule, and micro-calorimetric methods used to quantitate bicarbonate reabsorption. Experiments were carried out in control conditions, during dietary potassium withdrawal, and after acute intravenous infusions of carbonic anhydrase. We observed highly significant net bicarbonate reabsorption in normal acid-base conditions as evidenced by the maintenance of significant bicarbonate concentration gradients in the presence of vigorous fluid absorption. Distal bicarbonate reabsorption persisted in hypokalemic alkalosis and even steeper transepithelial concentration gradients of bicarbonate were maintained. Enhancement of net bicarbonate reabsorption followed the acute intravenous administration of carbonic anhydrase but was limited to the nephron segments between the late proximal and early distal tubule. The latter observation is consistent with a disequilibrium pH along the proximal straight tubule (S3 segment), the thick ascending limb of Henle, and/or the early distal tubule.