Bachmann S, Velázquez H, Obermüller N, Reilly R F, Moser D, Ellison D H
Department of Anatomy and Cell Biology, University of Heidelberg, Germany.
J Clin Invest. 1995 Nov;96(5):2510-4. doi: 10.1172/JCI118311.
A thiazide-sensitive Na-Cl cotransporter contributes importantly to mammalian salt homeostasis by mediating Na-Cl transport along the renal distal tubule. Although it has been accepted that thiazide-sensitive Na-Cl cotransport occurs predominantly along the distal convoluted tubule in rats and mice, sites of expression in the rabbit have been controversial. A commonly accepted model of rabbit distal nephron transport pathways identifies the connecting tubule, not the distal convoluted tubule, as the predominant site of thiazide-sensitive Na-Cl cotransport. The thiazide-sensitive Na-Cl cotransporter has been cloned recently. The present experiments were designed to localize sites of thiazide-sensitive Na-Cl cotransporter mRNA expression along the rabbit distal nephron. Nonradioactive in situ hybridization with a thiazide-sensitive Na-Cl cotransporter probe was combined with immunocytochemistry with an antibody that recognizes distal convoluted tubule cells and with a Na+/Ca2+ exchanger antibody that recognizes only connecting tubule cells. The results indicate that thiazide-sensitive Na-Cl cotransporter mRNA is highly expressed by cells of the distal convoluted tubule and not by connecting tubule cells. Segments that stain with the Na+/Ca2+ exchanger antibody (connecting tubules) do not demonstrate thiazide-sensitive Na-Cl cotransporter mRNA expression. We conclude that the predominant site of thiazide-sensitive Na-Cl cotransporter mRNA expression in rabbit distal nephron is the distal convoluted tubule and that sites of mRNA expression of electroneutral Na and Cl transport are similar in rabbits, rats, and mice.
噻嗪类敏感的钠氯共转运体通过介导肾远端小管的钠氯转运，对哺乳动物的盐稳态起着重要作用。虽然人们已经公认，噻嗪类敏感的钠氯共转运主要发生在大鼠和小鼠的远曲小管，但在兔子中的表达部位一直存在争议。一种被广泛接受的兔子远端肾单位转运途径模型认为，连接小管而非远曲小管是噻嗪类敏感的钠氯共转运的主要部位。噻嗪类敏感的钠氯共转运体最近已被克隆。本实验旨在定位兔子远端肾单位中噻嗪类敏感的钠氯共转运体mRNA的表达部位。将用噻嗪类敏感的钠氯共转运体探针进行的非放射性原位杂交与用识别远曲小管细胞的抗体以及仅识别连接小管细胞的钠/钙交换体抗体进行的免疫细胞化学相结合。结果表明，噻嗪类敏感的钠氯共转运体mRNA在远曲小管细胞中高度表达，而在连接小管细胞中不表达。用钠/钙交换体抗体染色的节段（连接小管）未显示噻嗪类敏感的钠氯共转运体mRNA表达。我们得出结论，兔子远端肾单位中噻嗪类敏感的钠氯共转运体mRNA表达的主要部位是远曲小管，并且电中性钠和氯转运的mRNA表达部位在兔子、大鼠和小鼠中相似。
