Stein J H, Osgood R W, Boonjarern S, Ferris T F
J Clin Invest. 1973 Sep;52(9):2313-23. doi: 10.1172/JCI107420.
Studies were designed to compare the segmental analysis of sodium reabsorption along the nephron during volume expansion with either 10% body weight Ringer's or 0.6% body weight hyperoncotic albumin. Total kidney and nephron glomerular filtration rate increased similarly with both, but urinary sodium excretion (12.7 vs. 4.0 mueq/min, P < 0.001) and fractional sodium excretion (5.0 vs. 1.6%, P < 0.001) increased to a greater extent with Ringer's. Fractional reabsorption of sodium in the proximal tubule was diminished in both groups but to a significantly greater extent during Ringer's (P < 0.005). Absolute reabsorption was inhibited only in the Ringer's group. Delivery of filtrate out of the proximal tubule was greater in the Ringer's studies, 45 vs. 37 nl/min (P < 0.001). However, both fractional and absolute sodium delivery to the early and late distal tubule were not significantly different in the two groups. Fractional reabsorption in the collecting duct decreased from 96% in hydropenia to 31% during Ringer's but fell only slightly to 80% in the albumin studies. Absolute collecting duct reabsorption was also greater in the albumin studies, 0.55 vs. 0.21 neq/min (P < 0.001), which could totally account for the difference in urinary sodium excretion between the two groups. (22)Na recovery in the final urine after end distal microinjections was 71% during Ringer's infusion and 34% during albumin (P < 0.001). From these data we conclude that: (a) Ringer's solution has a greater inhibitory effect on proximal tubular sodium reabsorption, and (b) in spite of this effect, differences in mucosal to serosal collecting duct sodium transport are primarily responsible for the greater natriuresis during Ringer's infusion.
研究旨在比较容量扩张时，分别用10%体重的林格氏液或0.6%体重的高渗白蛋白，沿肾单位进行钠重吸收的节段分析。两种情况下，总肾和肾单位肾小球滤过率的增加相似，但林格氏液组的尿钠排泄量（12.7对4.0微当量/分钟，P<0.001）和钠排泄分数（5.0对1.6%，P<0.001）增加幅度更大。两组近端小管钠的重吸收分数均降低，但林格氏液组降低幅度显著更大（P<0.005）。绝对重吸收仅在林格氏液组受到抑制。林格氏液组近端小管滤过液的流出量更大，为45对37纳升/分钟（P<0.001）。然而，两组早期和晚期远端小管钠的输送分数和绝对输送量无显著差异。集合管钠的重吸收分数在缺水时为96%，林格氏液组时降至31%，而在白蛋白组仅略有下降至80%。白蛋白组集合管钠的绝对重吸收也更大，为0.55对0.21纳当量/分钟（P<0.001），这完全可以解释两组尿钠排泄的差异。远端微注射后终尿中(22)Na的回收率，林格氏液输注时为71%，白蛋白组时为34%（P<0.001）。根据这些数据我们得出结论：(a)林格氏液对近端小管钠重吸收的抑制作用更强；(b)尽管有此作用，但林格氏液输注时尿钠排泄增加幅度更大，主要是由于集合管黏膜到浆膜钠转运的差异。
