Wen S F
Am J Physiol. 1976 Aug;231(2):468-75. doi: 10.1152/ajplegacy.1976.231.2.468.
Clearance and micropuncture studies were performed in 23 dogs without glucose loading to examine the tubule mechanism of renal glycosuria. Studies were carried out in three groups of animals before and after 10% extracellular volume expansion, and administration of maleic acid in low dose at 150 mumol/kg and in high dose at 300 mumol/kg. Specific hexokinase methods were used for the determination of glucose in tubule fluid and urine. Under control conditios, glucose reabsorption occurred predominantly in the proximal tubule. In all three groups, proximal tubule reabsorption of both sodium and glucose was inhibited in the second phase, showing a good correlation between the two. In contrast, fractional urinary glucose excretion remained unchanged after volume expansion and low-dose maleic acid, indicating reabsorption of virtually all the increased glucose load at a further "distal" site. On the other hand, significant glycosuria developed after high-dose maleic acid that was a result of reduced glucose reabsorption in the distal nephron, in addition to the proximal effect. It was concluded that distal glucose transport plays a significant role in regulating urinary glucose excretion and maintains renal thershold for glucose,
对23只未进行葡萄糖负荷的狗进行了清除率和微穿刺研究，以检查肾性糖尿的肾小管机制。在三组动物中，在细胞外液量扩张10%之前和之后，以及分别以150 μmol/kg的低剂量和300 μmol/kg的高剂量给予马来酸后进行了研究。采用特定的己糖激酶方法测定肾小管液和尿液中的葡萄糖。在对照条件下，葡萄糖重吸收主要发生在近端小管。在所有三组中，第二阶段近端小管对钠和葡萄糖的重吸收均受到抑制，两者之间显示出良好的相关性。相比之下，在容量扩张和低剂量马来酸后，尿葡萄糖排泄分数保持不变，表明几乎所有增加的葡萄糖负荷在更远端的部位被重吸收。另一方面，高剂量马来酸后出现显著糖尿，这是除近端效应外远端肾单位葡萄糖重吸收减少的结果。得出的结论是，远端葡萄糖转运在调节尿葡萄糖排泄中起重要作用，并维持肾葡萄糖阈值。
