Urinary concentrating ability in patients with Jk(a-b-) blood type who lack carrier-mediated urea transport.
Urinary concentrating ability in patients with Jk(a-b-) blood type who lack carrier-mediated urea transport.
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发表时间：
1992-06
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通讯作者：
J. Sands;J. Gargus;O. Fröhlich;R. Gunn;J. Kokko
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作者：
J. Sands;J. Gargus;O. Fröhlich;R. Gunn;J. Kokko
水的体内平衡在很大程度上是由尿浓缩机制的正常运作来调节的。在肾内髓中，尿素从内髓集合管再循环到内髓髓质被认为是产生浓缩尿的必要条件;然而，尚不可能在人体中检验这一假设。最近，一个独特的组合的遗传异常已被描述：缺乏基德血型抗原和载体介导的尿素转运红细胞的情况下。由于动物研究表明红细胞和肾单位中尿素转运的相似性，因此推测没有Kidd抗原的患者可能缺乏肾脏中的易化尿素转运。因此，测量了它们最大限度浓缩尿液的能力。目前的肾单位功能模型预测，在完全缺乏尿素转运的情况下，最大浓缩能力约为800至900 mosM/kg H2O。两个纯合子患者的最大集中能力（UosM，max = 819 mosM/kg H2O）中度下降;杂合子也有一定的限制。这些研究提出了红细胞尿素转运蛋白和肾脏尿素转运蛋白由单个基因编码（通过Kidd抗原的突变丢失检测）的可能性，以及缺乏易化尿素转运会损害肾脏中的尿素再循环，从而损害最大尿浓缩能力。
Water homeostasis is regulated in large part by the proper operation of the urinary concentrating mechanism. In the renal inner medulla, urea recycling from the inner medullary collecting duct to the inner medullary interstitium is thought to be essential for the production of a concentrated urine; however, it has not been possible to test this hypothesis in humans. Recently, a unique combination of genetic abnormalities has been described: absence of Kidd blood group antigens and absence of carrier-mediated urea transport in erythrocytes. Because animal studies indicate a similarity between urea transport in red blood cells and the nephron, it was postulated that patients without the Kidd antigen might lack facilitated urea transport in their kidneys. Hence, their ability to concentrate urine maximally was measured. Current models of nephron function would predict that in the complete absence of urea transport, the maximal concentrating ability would be around 800 to 900 mosM/kg H2O. Two homozygous patients had a moderate decrease in maximal concentrating ability (UosM,max = 819 mosM/kg H2O); a heterozygote also had some limitation. These studies raise the possibility that the erythrocyte urea transporter and the kidney urea transporter are encoded by a single gene (detected by the mutational loss of the Kidd antigen) and that a lack of facilitated urea transport impairs urea recycling in the kidney and, hence, maximal urinary concentrating ability.