Developmental changes in the tubular capacity for phosphate reabsorption in the rat.
Developmental changes in the tubular capacity for phosphate reabsorption in the rat.
复制标题
大鼠肾小管磷酸盐重吸收能力的发育变化。
DOI：
10.1152/ajprenal.1988.255.2.f287
复制
发表时间：
1988
期刊：
影响因子：
--
通讯作者：
Webster,SK
中科院分区：
文献类型：
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作者：
Haramati,A;Mulroney,SE;Webster,SK
众所周知，幼小、未成熟的动物需要保持正磷酸盐平衡才能生长。然而，这一过程是否涉及肾脏重吸收磷酸盐的内在能力的变化尚不清楚。在本研究中，测量了四组处于不同发育阶段（从断奶到成年（3-4周、5-6周、10-14周和52周））的大鼠的磷酸盐重吸收最大能力[最大RPi/肾小球滤过率（GFR）]。在存在和不存在固定水平的甲状旁腺激素（合成 PTH-(1-34)，1 U.kg-1.min-1）的情况下，在急性甲状腺甲状旁腺切除 (TPTX) 大鼠中进行清除实验。最大 RPi/GFR 通过逐步输注磷酸盐（0-6 微摩尔 Pi/分钟）来确定，这会增加磷酸盐的过滤负荷。 TPTX 3至4周龄和5至6周龄大鼠的最大RPi/GFR（分别为5.55+/-0.36和4.28+/-0.18μmol/ml）显着高于相应的52周龄大鼠（3.51+/-0.13μmol/ml，P小于0.05）。 PTH 降低了所有年龄组的最大 RPi/GFR。然而，发育模式得以维持，与其他年龄组（5至6岁、10至14岁和10岁至14岁大鼠为1.92 +/- 0.23、1.35 +/- 0.11和1.15 +/- 0.13 mumol/ml）相比，最年轻的大鼠中存在最高水平（2.79 +/- 0.25 mumol/ml，P小于0.05）。分别为 52 周龄大鼠）。这些结果表明，未成熟大鼠中每毫升 GFR 的肾小管重吸收磷酸盐的能力增强，并随着年龄的增长而逐渐降低。幼鼠的这种不依赖于 PTH 的适应可能有助于生长过程中磷酸盐在肾中的滞留。
The need for young, immature animals to maintain positive phosphate balance for growth is well known. However, whether this process involves changes in the intrinsic capacity of the kidney to reabsorb phosphate is not clear. In the present study, the maximum capacity of phosphate reabsorption [Max RPi/glomerular filtration rate (GFR)] was measured in four groups of rats at different stages of development, from weanling to adulthood (3–4, 5–6, 10–14, and 52 wk of age). Clearance experiments were performed in acutely thyroparathyroidectomized (TPTX) rats in the presence and absence of fixed levels of parathyroid hormone (synthetic PTH-(1–34), 1 U.kg-1.min-1). Max RPi/GFR was determined with progressive infusions of phosphate (0–6 mumol Pi/min) that raised the filtered load of phosphate. Max RPi/GFR in TPTX 3- to 4- and 5- to 6-wk-old rats (5.55 +/- 0.36 and 4.28 +/- 0.18 mumol/ml, respectively) was significantly greater than in the corresponding 52-wk-old rats (3.51 +/- 0.13 mumol/ml, P less than 0.05). PTH decreased the Max RPi/GFR in all age groups. However, the developmental pattern was maintained, with the highest levels present in the youngest rats (2.79 +/- 0.25 mumol/ml, P less than 0.05) compared with the other age groups (1.92 +/- 0.23, 1.35 +/- 0.11, and 1.15 +/- 0.13 mumol/ml for 5- to 6-, 10- to 14-, and 52-wk-old rats, respectively). These results demonstrate that the tubular capacity for phosphate reabsorption per milliliter GFR is enhanced in immature rats and progressively decreases with age. This PTH-independent adaptation in young rats may contribute to the renal retention of phosphate during growth.