Functional expression of cAMP-dependent and independent urea transporters in Xenopus oocytes.
Functional expression of cAMP-dependent and independent urea transporters in Xenopus oocytes.
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非洲爪蟾卵母细胞中 cAMP 依赖性和非依赖性尿素转运蛋白的功能表达。
DOI：
10.1152/ajpcell.1993.265.2.c514
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Verkman,AS
中科院分区：
文献类型：
--
作者：
Hasegawa,H;Verkman,AS
肾脏内髓集合管促进尿素的运输对于尿液浓缩机制很重要。为了检查尿素转运蛋白的性质和组织分布，从不同组织中分离出 mRNA，并在非洲爪蟾卵母细胞中表达。在显微注射mRNA后64小时在21℃下测量[14C]尿素和[3H]甲基葡萄糖的摄取。注射 50 ng 未分级 mRNA 的卵母细胞的相对尿素摄取为 (n = 6-42)：1.0（注水对照）、1.0 +/- 0.3（人肾皮质）、2.9 +/- 0.5（大鼠肾乳头）、2.5 +/- 0.5（人肾乳头）、2.7 +/- 0.3（大鼠肝脏）、1.1 +/- 0.3（大鼠脑）、1.2 +/- 0.3（大鼠肌肉）和 2.6 +/- 0.3（兔网织红细胞）。在注射肾髓质、肝脏和网织红细胞 mRNA 的卵母细胞中，0.2 mM 根皮素和 0.2 mM 对氯汞苯磺酸盐 (pCMBS) 将尿素摄取抑制至接近对照值；根皮素和 pCMBS 对对照卵母细胞和注射肾皮质、大脑和肌肉 mRNA 的卵母细胞没有影响。通过与腺苷 3',5'-环单磷酸 (cAMP) 激动剂腺苷-3',5'-环单磷酸硫代酯 (Sp-cAMPS) 或喜树碱 (CPT-cAMP)、毛喉素和 3-异丁基-1-甲基黄嘌呤的混合物预孵育 5 分钟，注射肾髓质 mRNA 的卵母细胞的尿素摄取量显着增加（是对照的 4.4 倍）； cAMP 激动剂不影响表达网织红细胞和肝脏尿素转运蛋白的卵母细胞的尿素摄取。作为内部对照，（根皮素可抑制的）葡萄糖摄取在所有卵母细胞中均增强（比对照高出 5 倍），并且不受 pCMBS 和 cAMP 激动剂的影响。（摘要截短为 250 字）
Facilitated transport of urea by the inner medullary collecting duct in kidney is important for the urinary concentrating mechanism. To examine the nature and tissue distribution of urea transporters, mRNA was isolated from different tissues and expressed in Xenopus oocytes. [14C]urea and [3H]methylglucose uptake were measured at 21 degrees C at 64 h after microinjection of mRNA. Relative urea uptake in oocytes injected with 50 ng of unfractionated mRNA was (n = 6-42): 1.0 (water-injected control), 1.0 +/- 0.3 (human kidney cortex), 2.9 +/- 0.5 (rat kidney papilla), 2.5 +/- 0.5 (human kidney papilla), 2.7 +/- 0.3 (rat liver), 1.1 +/- 0.3 (rat brain), 1.2 +/- 0.3 (rat muscle), and 2.6 +/- 0.3 (rabbit reticulocyte). Urea uptake was inhibited to near control values by 0.2 mM phloretin and 0.2 mM p-chloromercuribenzenesulfonate (pCMBS) in oocytes injected with mRNA from kidney medulla, liver, and reticulocyte; phloretin and pCMBS had no effect in control oocytes and oocytes injected with mRNA from kidney cortex, brain, and muscle. Urea uptake was strongly increased in oocytes injected with kidney medulla mRNA (4.4-fold over control) by a 5-min preincubation with the adenosine 3',5'-cyclic monophosphate (cAMP) agonist adenosine-3',5'-cyclic monophosphorothioate (Sp-cAMPS) or a mixture of CPT-cAMP, forskolin, and 3-isobutyl-1-methylxanthine; cAMP agonists did not affect urea uptake in oocytes expressing the reticulocyte and liver urea transporters. As an internal control, (phloretin inhibitable) glucose uptake was enhanced in all oocytes (up to 5-fold greater than control), and was not affected by pCMBS and the cAMP agonists.(ABSTRACT TRUNCATED AT 250 WORDS)