Evidence for a concentration gradient favoring outward movement of sodium from the thin loop of Henle.
Evidence for a concentration gradient favoring outward movement of sodium from the thin loop of Henle.
复制标题
有利于钠从亨利细环向外移动的浓度梯度的证据。
DOI：
10.1172/jci108633
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发表时间：
1977
期刊：
影响因子：
--
通讯作者：
R. Jamison
中科院分区：
文献类型：
--
作者：
P. Johnston;C. Battilana;F. Lacy;R. Jamison
尿浓缩机制的最新模型假设，髓袢中的尿素在汉勒袢降支末端的液体和髓袢之间产生了一个经前庭的钠浓度梯度，有利于钠从汉勒氏细升支被动向外运动。这些实验旨在确定这种梯度是否正常存在。准备对未利尿的Munich-Wistar大鼠进行暴露的左肾乳头显微穿刺。从相邻部位采集Henle液袢和直血管血浆样本（假设反映间质液的组成）。来自18只大鼠的21次比较中的环液值（平均值+/- SE）为：钠344 +/- 12 meq/L;钾26 +/- 2 meq/L;渗透压938 +/- 37 mosmol/kg H23。直血管血浆值（相应的测量单位）为：钠，284 +/- 11;钾，34 +/- 2;渗透压，935 +/- 34。配对差异（袢液减去直血管血浆）的平均值为：δ钠，60 +/- 11.1（P <0.001）; δ钾，-8.0 +/- 2.1（P <0.001）; δ渗透压，4 +/- 16（NS）。校正血浆水分后，袢液减去直小血管的差异（单位：毫当量/千克H2O）为：δ钠，40 +/- 11.4（P小于0.005）; δ钾，-9.7 +/- 1.9（P小于0.001）。我们解释这些发现表明，在非利尿大鼠的乳头，钠浓度的显着差异存在于整个亨利氏细环有利于向外运动的钠，这证实了被动模型的关键要求。还观察到钾在相反方向上的浓度差异。
Recent models of the urinary concentrating mechanism have postulated that urea in the medullary interstitium creates a transtubular concentration gradient for sodium between fluid at the end of the descending limb of Henle's loop and the medullary interstitium, favoring the passive outward movement of sodium from Henle's thin ascending limb. These experiments were designed to determine whether such a gradient normally exists. Young nondiuretic Munich-Wistar rats were prepared for micropuncture of the exposed left renal papilla. Samples of loop of Henle fluid and vasa recta plasma (assumed to reflect the composition of interstitial fluid) were obtained from adjacent sites. Loop fluid values in 21 comparisons from 18 rats (mean +/- SE) were: sodium 344 +/- 12 meq/liter; potassium, 26 +/- 2 meq/liter; osmolality, 938 +/- 37 mosmol/kg H23. Vasa recta plasma values (in corresponding units of measurement) were: sodium, 284 +/- 11; potassium, 34 +/- 2; osmolality, 935 +/- 34. Mean values of paired differences (loop fluid minus vasa recta plasma) were: delta sodium, 60 +/- 11.1 (P less than 0.001); delta potassium, -8.0 +/- 2.1 (P less than 0.001); delta osmolality, 4 +/- 16 (NS). Corrected for plasma water, the loop fluid minus vasa recta differences (in milliequivalents per kilogram H2O) were: delta sodium, 40 +/- 11.4 (P less than 0.005); delta potassium, -9.7 +/- 1.9 (P less than 0.001). We interpret these findings to indicate that in the papilla of nondiuretic rats, a significant difference in sodium concentration exists across the thin loop of Henle favoring outward movement of sodium, which confirms a key requirement of the passive models. A concentration difference for potassium in the reverse direction was also observed.