Webster S K, Reineck H J, Stein J H
Proc Soc Exp Biol Med. 1985 May;179(1):96-100. doi: 10.3181/00379727-179-42069.
These experiments were designed to evaluate the hypothesis that K+ deficiency may be associated with decreased delivery of urea to the renal papillary collecting duct and/or decreased reabsorption of urea from the papillary collecting duct. Either of these factors would result in diminished capacity for urea recycling and might explain the mechanism of the urinary concentrating defect that is observed in K+ depletion. Munich-Wistar rats were fed 25 ml of water and 12 g of normal (CON) or K+-deficient (KD) diet each day for 21 days. Papillary collecting duct samples were obtained by micropuncture through the intact ureter. Fractional delivery of H2O to the base and tip of the papillary collecting duct was increased in KD as compared to CON rats (1.50 +/- 0.30% in KD vs 0.72 +/- 0.09% in CON at the base, P less than 0.01; and 0.55 +/- 0.08% in KD vs 0.30 +/- 0.05% in CON at the tip, P less than 0.01). However, fractional delivery of urea to the base and tip of the papillary collecting duct was not different between KD and CON rats (26.9 +/- 5.6% in KD vs 21.4 +/- 3.3% in CON at the base, P greater than 0.05; and 12.4 +/- 1.5% in KD vs 10.4 +/- 1.4% in CON at the tip, P greater than 0.05). Furthermore, reabsorption of water or urea between the base and tip of the papillary collecting duct was not decreased in KD as compared to CON rats (water reabsorption was 57.8 +/- 4.4% in KD and 55.9 +/- 5.11% in CON and urea reabsorption was 45.0 +/- 6.5% in KD and 45.9 +/- 5.4% in CON, P greater than 0.05). These results demonstrate that water reabsorption, but not urea reabsorption, is impaired in renal tubules proximal to the accessible papillary collecting duct in hydropenic rats.
钾缺乏可能与尿素输送至肾乳头集合管减少和/或肾乳头集合管对尿素的重吸收减少有关。这两种因素中的任何一种都会导致尿素再循环能力下降，并可能解释钾缺乏时观察到的尿液浓缩功能缺陷的机制。将慕尼黑-维斯塔大鼠每天喂以25毫升水和12克正常（CON）或低钾（KD）饮食，持续21天。通过微穿刺完整输尿管获取肾乳头集合管样本。与CON大鼠相比，KD大鼠肾乳头集合管基部和顶端的水分数输送增加（基部：KD组为1.50±0.30%，CON组为0.72±0.09%，P<0.01；顶端：KD组为0.55±0.08%，CON组为0.30±0.05%，P<0.01）。然而，KD大鼠和CON大鼠肾乳头集合管基部和顶端的尿素分数输送没有差异（基部：KD组为26.9±5.6%，CON组为21.4±3.3%，P>0.05；顶端：KD组为12.4±1.5%，CON组为10.4±1.4%，P>0.05）。此外，与CON大鼠相比，KD大鼠肾乳头集合管基部和顶端之间的水或尿素重吸收没有减少（水重吸收：KD组为57.8±4.4%，CON组为55.9±5.11%；尿素重吸收：KD组为45.0±6.5%，CON组为45.9±5.4%，P>0.05）。这些结果表明，在缺水大鼠中，可及肾乳头集合管近端的肾小管中水重吸收受损，但尿素重吸收未受损。
