Wong N L, Quamme G A, Dirks J H
Kidney Int. 1984 Jun;25(6):912-8. doi: 10.1038/ki.1984.109.
In this study, micropuncture experiments were performed to examine the segmental reabsorption of bicarbonate and chloride in the normal dog kidney (stage 1) and in the remnant kidney (stage 3) of dogs with experimental renal failure. The protocol consisted of three phases: (1) 3% extracellular fluid volume expansion, (2) infusion of Ringer's solution containing 90 mM of sodium bicarbonate, and (3) infusion of 150 mM of sodium bicarbonate in Ringer's solution. In the animals with remnant stage 3 kidneys, the ratio of absolute bicarbonate reabsorption/absolute sodium reabsorption was increased compared to dogs with stage 1 kidneys at both the proximal and distal sampling sites. These data suggest that bicarbonate reabsorption was elevated in both the distal and the proximal tubules in experimental chronic renal failure. In contrast to the reabsorption of bicarbonate, chloride reabsorption was depressed in stage 3 kidneys at the late proximal puncture site. This resulted in greater delivery to the distal nephron. The distal segments reabsorbed a constant fraction of delivered chloride, resulting in an increase in fractional chloride excretion in chronic renal failure compared to that in normal animals.
在本研究中，进行了微穿刺实验，以检查正常犬肾（1期）和实验性肾衰竭犬的残余肾（3期）中碳酸氢根和氯离子的节段性重吸收情况。实验方案包括三个阶段：（1）细胞外液量扩张3%，（2）输注含90 mM碳酸氢钠的林格氏液，（3）输注含150 mM碳酸氢钠的林格氏液。在残余肾为3期的动物中，在近端和远端采样部位，与1期肾脏的犬相比，绝对碳酸氢根重吸收/绝对钠重吸收的比值均升高。这些数据表明，在实验性慢性肾衰竭中，远端和近端小管的碳酸氢根重吸收均增加。与碳酸氢根重吸收不同，在3期肾脏的近端穿刺晚期部位，氯离子重吸收降低。这导致更多的氯离子输送到远端肾单位。远端节段重吸收恒定比例的输送来的氯离子，导致慢性肾衰竭时氯离子排泄分数相对于正常动物增加。
