A MICROPUNCTURE STUDY OF RENAL LITHIUM REABSORPTION - EFFECTS OF AMILORIDE AND FUROSEMIDE
A MICROPUNCTURE STUDY OF RENAL LITHIUM REABSORPTION - EFFECTS OF AMILORIDE AND FUROSEMIDE
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DOI：
10.1152/ajprenal.1992.263.6.f1128
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发表时间：
1992-12-01
影响因子：
--
通讯作者：
SAMPSON, B
中科院分区：
文献类型：
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作者：
SHIRLEY, DG;WALTER, SJ;SAMPSON, B
锂清除技术作为近端液体输送的测量方法的有效性在钠充足的Inactin麻醉的Sprague-Dawley大鼠中使用微穿刺进行评估。使用三组动物：对照组、阿米洛利治疗组和呋塞米治疗组。利尿剂引起的盐和水损失被取代。对照组、阿米洛利组和呋塞米组的锂排泄分数（FE（Li））分别为0.23 +/- 0.01、0.24 +/- 0.02和0.40 +/- 0.03。在每一组中，近曲小管末端（PCT）的肾小管液与血浆锂浓度比显著大于1（对照组，1.16 +/- 0.03;阿米洛利，1.16 +/- 0.02;呋塞米，1.17 +/- 0.02）。在对照组中，晚期PCT的锂输送分数（FD（Li））为0.50 +/- 0.02，而早期远端小管的FD（Li）为0.25 +/- 0.01;后者与晚期远端小管的FD（Li）或FE（Li）无显著差异。阿米洛利治疗大鼠的数值几乎相同。呋塞米对晚期PCT的FD（Li）没有影响，但将早期远端小管的FD（Li）提高至0.37 +/- 0.03。我们得出结论：1）PCT中的锂重吸收略微滞后于水，2）在PCT之外发生大量呋塞米敏感的锂重吸收，3）在袢之外的肾单位节段中没有发生显著的锂重吸收。这些发现质疑使用锂清除率作为钠充足动物中近端液体输送的定量测量。
The validity of the lithium clearance technique as a measure of end-proximal fluid delivery was assessed using micropuncture in sodium-replete, Inactin-anesthetized Sprague-Dawley rats. Three groups of animals were used: controls, amiloride treated, and furosemide treated. Diuretic-induced salt and water losses were replaced. Fractional lithium excretion (FE(Li)) Was 0.23 +/- 0.01, 0.24 +/- 0.02, and 0.40 +/- 0.03 in the control, amiloride, and furosemide groups, respectively. In each group, the tubular fluid-to-plasma lithium concentration ratio at the end of the proximal convoluted tubule (PCT) was significantly greater than unity (control, 1.16 +/- 0.03; amiloride, 1.16 +/- 0.02; furosemide, 1.17 +/- 0.02). In the control group, fractional lithium delivery (FD(Li)) at the late PCT was 0.50 +/- 0.02, while FD(Li) at the early distal tubule was 0.25 +/- 0.01; the latter did not differ significantly from FD(Li) at the late distal tubule or from FE(Li). Values in amiloride-treated rats were almost identical. Furosemide had no effect on FD(Li) at the late PCT, but raised that at the early distal tubule to 0.37 +/- 0.03. We conclude that 1) lithium reabsorption in the PCT lags slightly behind that of water, 2) substantial furosemide-sensitive lithium reabsorption occurs beyond the PCT, and 3) no significant lithium reabsorption occurs in nephron segments beyond the loop. These findings call into question the use of lithium clearance as a quantitative measure of end-proximal fluid delivery in sodium-replete animals.