Active sodium-urea counter-transport is inducible in the basolateral membrane of rat renal initial inner medullary collecting ducts.
Active sodium-urea counter-transport is inducible in the basolateral membrane of rat renal initial inner medullary collecting ducts.
复制标题
大鼠肾初始内髓集合管的基底外侧膜可诱导活性钠-尿素逆向转运。
DOI：
10.1172/jci3588
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Sands,JM
中科院分区：
文献类型：
--
作者：
Kato,A;Sands,JM
大鼠内髓集合管（IMCD 3s）具有管腔Na+依赖性，主动尿素分泌运输过程，这是上调水利尿。在这项研究中，灌注IMCDs显微解剖的基础（IMCD 1），中间（IMCD 2），或提示（IMCD 3）的内部髓质，我们测试是否呋塞米利尿改变主动尿素转运。大鼠接受呋塞米（10 mg/d s.c. 3-4 d），并与配对喂养的对照组大鼠进行比较。呋塞米显著降低尿渗透压和尿素清除率，增加血尿素氮。呋塞米处理大鼠的IMCD 3活性尿素分泌率显著低于对照大鼠的IMCD 3。IMCD 2在对照组或呋塞米治疗组大鼠中未显示出活性尿素转运。对照组大鼠的IMCD 1 s没有主动尿素转运，但呋塞米治疗组大鼠的IMCD 1 s表达了显著的主动尿素重吸收率。在IMCD 1 s中，这种活性尿素重吸收转运过程被以下物质抑制：（i）0. 25 mM根皮素（浴）;（ii）1 mM哇巴因（浴）;和（iii）用NMDG+代替Na+浴;用10 nM布美他尼（浴）刺激。总之，我们发现呋塞米减少IMCD 3的活性尿素分泌，并诱导IMCD 1的活性尿素重吸收。这种新的Na+依赖的、活跃的尿素重吸收转运过程可能是一种基底外侧Na+-尿素反向转运蛋白。
Rat inner medullary collecting ducts (IMCD3s) possess a luminal Na+-dependent, active urea secretory transport process, which is upregulated by water diuresis. In this study of perfused IMCDs microdissected from base (IMCD1), middle (IMCD2), or tip (IMCD3) of the inner medulla, we tested whether furosemide diuresis alters active urea transport. Rats received furosemide (10 mg/d s.c. for 3-4 d) and were compared with pair-fed control rats. Furosemide significantly decreased urine osmolality and urea clearance, and increased blood urea nitrogen. IMCD3s from furosemide-treated rats had significantly lower rates of active urea secretion than IMCD3s from control rats. IMCD2s showed no active urea transport in control or furosemide-treated rats. IMCD1s from control rats had no active urea transport, but IMCD1s from furosemide-treated rats expressed significant rates of active urea reabsorption. In IMCD1s, this active urea reabsorptive transport process was inhibited by: (i) 0. 25 mM phloretin (bath); (ii) 1 mM ouabain (bath); and (iii) replacing bath Na+ with NMDG+; it was stimulated by 10 nM bumetanide (bath). In summary, we found that furosemide decreased active urea secretion in IMCD3s and induced active urea reabsorption in IMCD1s. The new Na+- dependent, active urea reabsorptive transport process may be a basolateral Na+-urea antiporter.