Terada Y, Tomita K, Nonoguchi H, Yang T, Marumo F
Second Department of Internal Medicine, Tokyo Medical and Dental University, Japan.
Kidney Int. 1993 Dec;44(6):1273-80. doi: 10.1038/ki.1993.379.
Endothelin (ET) is now known to be a family of three distinct peptides. Although many reports have studied the renal action of ET-1, comparatively little is known concerning ET-3. We previously reported that ET-1 mRNA is expressed in glomerulus (Glm) and inner medullary collecting duct (IMCD). In this study, microlocalization of mRNA coding ET-3 was carried out in the rat kidney using a reverse transcription and polymerase chain reaction (RT-PCR) assay of individual microdissected renal tubule segments along the nephron, Glm, vasa recta bundle, and arcuate arteries. Large signals for ET-3 PCR product were detected in proximal convoluted and straight tubules, cortical collecting duct, and outer medullary collecting duct. Glm, IMCD, and vasa recta bundle also expressed relatively large amounts of ET-3 mRNA. Small signals were found in medullary thick ascending limb, inner medullary thin limb, and arcuate artery. We detected ET-3 protein in tubule suspensions from cortex, outer medulla, and inner medulla of rat kidney. Furthermore, incubation with TGF-beta did not change ET-3 PCR signal, whereas ET-1 PCR signal was increased significantly by exposure to TGF-beta in Glm and IMCD. Thus, ET-3 and ET-1 are distributed differently along the nephron and are regulated in different manners. This suggests that ET-3 and ET-1 may affect kidney functions in different ways.
内皮素（ET）现已知是由三种不同肽组成的一个家族。尽管许多报告研究了ET-1的肾脏作用，但关于ET-3的了解相对较少。我们先前报道ET-1 mRNA在肾小球（Glm）和髓质内集合管（IMCD）中表达。在本研究中，使用逆转录聚合酶链反应（RT-PCR）分析沿着肾单位、Glm、直小血管束和弓状动脉的单个显微解剖肾小管段，对编码ET-3的mRNA进行了微定位。在近端曲管和直小管、皮质集合管和外髓集合管中检测到ET-3 PCR产物的大信号。Glm、IMCD和直小血管束也表达相对大量的ET-3 mRNA。在髓质厚升支、髓质内细段和弓状动脉中发现小信号。我们在大鼠肾脏皮质、外髓和内髓的肾小管悬液中检测到ET-3蛋白。此外，用转化生长因子-β（TGF-β）孵育不会改变ET-3 PCR信号，而在Glm和IMCD中，暴露于TGF-β会使ET-1 PCR信号显著增加。因此，ET-3和ET-1在肾单位中的分布不同，且受到不同方式的调节。这表明ET-3和ET-1可能以不同方式影响肾脏功能。
