Immunolocalization of NBC3 and NHE3 in the rat epididymis: colocalization of NBC3 and the vacuolar H+-ATPase.
Immunolocalization of NBC3 and NHE3 in the rat epididymis: colocalization of NBC3 and the vacuolar H+-ATPase.
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DOI：
10.1002/j.1939-4640.2000.tb02139.x
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发表时间：
2000-09
影响因子：
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通讯作者：
A. Pushkin;Imran B. Clark;Tae-Hwan Kwon;Søren Nielsen;Ira Kurtz
中科院分区：
文献类型：
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作者：
A. Pushkin;Imran B. Clark;Tae-Hwan Kwon;Søren Nielsen;Ira Kurtz
在男性生殖道中，附精在介导跨上皮碳酸氢盐运输和管腔酸化方面起着重要作用。在近端输精管，管腔酸化的一个重要组成部分是不依赖于Na+的，并由具有顶端液泡质子泵的特定细胞介导。相反，附睾尾的管腔酸化是安娜离子依赖的过程。导致管腔酸化的特定顶端依赖于Na+的H+/碱转运过程(ES)尚未确定。附睾和哺乳动物肾单位之间的运输特性的相似性为这些顶端依赖Na+的H+/碱转运体(S)的识别提供了潜在的线索。附睾头的H~+/碱基转运特性与哺乳动物肾近端小管相似，而附睾头和输精管的H~+/碱转运特性与肾集合管间质细胞相似。鉴于已知Na+/H+逆向转运蛋白NHE3在近端小管中的表达，以及电中和碳酸氢钠共转运蛋白NBC3在肾间质细胞中的表达，我们确定了NHE3和NBC3在大鼠附睾部不同区域的定位。NBC3在附睾头尖(窄)细胞、附睾体和附睾尾的浅色(透明)细胞上高表达。附睾尾表达顶端NBC3的细胞数最多。NBC3在附精中的定位与液泡型H+-ATPase相同。结果表明，NBC3和空泡H+-ATPase的共定位不局限于肾间质细胞。此外，这两种转运蛋白的密切联系似乎是在表达高水平液泡H+-ATPase的细胞中更普遍的现象。与NBC3不同，NHE3在附睾头所有上皮细胞的顶膜上高表达，在附睾体表达较少，在尾部不表达。这些结果表明，NHE3和NBC3在调节附睾腔内H+/碱基转运中可能起重要作用。
In the male reproductive tract, the epididymis plays an important role in mediating transepithelial bicarbonate transport and luminal acidification. In the proximal vas deferens, a significant component of luminal acidification is Na+-independent, and mediated by specific cells that possess apical vacuolar proton pumps. In contrast, luminal acidification in the cauda epididymidis is an Na+-dependent process. The specific apical Na+-dependent H+/base transport process(es) responsible for luminal acidification have not been identified. A potential clue as to the identity of these apical Na+-dependent H+/base transporter(s) is provided by similarities between the transport properties of the epididymis and the mammalian nephron. Specifically, the H+/base transport properties of caput epididymidis resemble the mammalian renal proximal tubule, whereas the distal epididymis and vas deferens have characteristics in common with renal collecting duct intercalated cells. Given the known expression of the Na+/H+ antiporter, NHE3, in the proximal tubule, and of the electroneutral sodium bicarbonate cotransporter, NBC3, in renal intercalated cells, we determined the localization of NHE3 and NBC3 in various regions of rat epididymis. NBC3 was highly expressed on the apical membrane of apical (narrow) cells in caput epididymidis, and light (clear) cells in corpus and cauda epididymidis. The number of cells expressing apical NBC3 was highest in cauda epididymidis. The localization of NBC3 in the epididymis was identical to the vacuolar H+-ATPase. The results indicate that colocalization of NBC3 and the vacuolar H+-ATPase is not restricted to kidney intercalated cells. Moreover, the close association of the two transporters appears to be a more generalized phenomenon in cells that express high levels of vacuolar H+-ATPase. Unlike NBC3, NHE3 was most highly expressed on the apical membrane of all epithelial cells in caput epididymidis, with less expression in the corpus, and no expression in the cauda. These results suggest that apical NBC3 and NHE3 potentially play an important role in mediating luminal H+/base transport in epididymis.