Foulkes E C, Blanck S
Department of Environmental Health, University of Cincinnati, College of Medicine, Ohio 45267-0056.
Proc Soc Exp Biol Med. 1990 Jan;193(1):56-9. doi: 10.3181/00379727-193-42990.
During passage from renal artery to vein, nonfiltered amino acids are known to be extracted by the kidney, an observation generally attributed to their basolateral uptake by tubular epithelium. This attribution is here tested in the rabbit, using the nonmetabolizable analogue cycloleucine as test compound. Uptake of cycloleucine is diffusion limited and could be maximized by lengthening its artery-to-vein transit time by short aortic occlusion. The transient anoxia did not abolish active solute transport in the kidney; the technique permits acute loading of the kidney with, for instance, a nephrotoxicant without excessive exposure of the whole animal. The major portion of cycloleucine taken up by nonfiltering kidneys during occlusion returned to renal venous plasma with a mean delay of 45 sec, as if it had accumulated in the same cellular transport pool through which reabsorbed cycloleucine has to pass. A fraction of the amino acid taken up also reached the tubular lumen. These results support the suggested role of tubule cells in the extraction of amino acids from postglomerular blood.
在从肾动脉到肾静脉的过程中，已知未被滤过的氨基酸会被肾脏摄取，这一现象通常归因于肾小管上皮细胞对其基底外侧的摄取。在此，使用不可代谢的类似物环亮氨酸作为测试化合物，在兔子身上对这一归因进行了验证。环亮氨酸的摄取受扩散限制，可通过短暂阻断主动脉来延长其从动脉到静脉的转运时间，从而使其摄取最大化。短暂缺氧并未消除肾脏中的主动溶质转运；该技术允许例如向肾脏急性加载肾毒性物质，而不会使整个动物过度暴露。在阻断期间，未进行滤过的肾脏摄取的大部分环亮氨酸平均延迟45秒后返回肾静脉血浆，就好像它积聚在与重吸收的环亮氨酸必须通过的相同细胞转运池中。摄取的一部分氨基酸也到达了肾小管管腔。这些结果支持了肾小管细胞在从肾小球后血液中提取氨基酸过程中所起作用的观点。
