Abstract
Sodium and chloride transport by the macula densa and thick ascending limb of Henle's loop participates importantly in extracellular fluid volume homeostasis, urinary concentration and dilution, control of glomerular filtration, and control of renal hemodynamics. Transepithelial Na and Cl transport across the apical membrane of thick ascending limb (TALH) cells is mediated predominantly by a loop diuretic sensitive Na-K-2Cl cotransport pathway. The corresponding transport protein has recently been cloned. Functional studies suggest that the cotransporter is expressed by macula densa cells as well as by TALH cells. The current studies were designed to identify sites of Na-K-2Cl cotransporter expression along distal nephron in rabbit and rat. Non-isotopic high-resolution in situ hybridization, using an antisense probe for the apical form of the Na-K-2Cl cotransporter identified expression throughout the TALH, from the junction between inner and outer medulla to the transition to distal convoluted tubule. Expression by macula densa cells was confirmed by colocalization using markers specific for macula densa cells. First, Na-K-2Cl cotransporter mRNA was detected in macula densa cells that did not stain with anti-Tamm-Horsfall protein antibodies. Second, Na-K-2Cl cotransporter mRNA was detected in macula densa cells that show positive NADPH-diaphorase reaction, indicating high levels of constitutive nitric oxide synthase activity. In rat, levels of Na-K-2Cl cotransporter mRNA expression were similar in TALH and macula densa cells. In rabbit, expression levels were higher in macula densa cells than in surrounding TALH cells. The present data provide morphological support for a previously established functional concept that Na-K-2Cl cotransport at the TALH is accomplished by the expression of a well-defined cotransporter. At the macula densa, this transporter may establish a crucial link between tubular salt load and glomerular vascular regulation.
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Selected References
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- Bachmann S., Bosse H. M., Mundel P. Topography of nitric oxide synthesis by localizing constitutive NO synthases in mammalian kidney. Am J Physiol. 1995 May;268(5 Pt 2):F885–F898. doi: 10.1152/ajprenal.1995.268.5.F885. [DOI] [PubMed] [Google Scholar]
- Bachmann S., Le Hir M., Eckardt K. U. Co-localization of erythropoietin mRNA and ecto-5'-nucleotidase immunoreactivity in peritubular cells of rat renal cortex indicates that fibroblasts produce erythropoietin. J Histochem Cytochem. 1993 Mar;41(3):335–341. doi: 10.1177/41.3.8429197. [DOI] [PubMed] [Google Scholar]
- Bachmann S., Mundel P. Nitric oxide in the kidney: synthesis, localization, and function. Am J Kidney Dis. 1994 Jul;24(1):112–129. doi: 10.1016/s0272-6386(12)80170-3. [DOI] [PubMed] [Google Scholar]
- Bell P. D., Lapointe J. Y., Cardinal J., Chang Y. S. Transport pathways in macula densa cells. Kidney Int Suppl. 1991 Jun;32:S59–S64. [PubMed] [Google Scholar]
- Bosse H. M., Böhm R., Resch S., Bachmann S. Parallel regulation of constitutive NO synthase and renin at JGA of rat kidney under various stimuli. Am J Physiol. 1995 Dec;269(6 Pt 2):F793–F805. doi: 10.1152/ajprenal.1995.269.6.F793. [DOI] [PubMed] [Google Scholar]
- Gamba G., Miyanoshita A., Lombardi M., Lytton J., Lee W. S., Hediger M. A., Hebert S. C. Molecular cloning, primary structure, and characterization of two members of the mammalian electroneutral sodium-(potassium)-chloride cotransporter family expressed in kidney. J Biol Chem. 1994 Jul 1;269(26):17713–17722. [PubMed] [Google Scholar]
- Haas M., Forbush B., 3rd Photolabeling of a 150-kDa (Na + K + Cl) cotransport protein from dog kidney with a bumetanide analogue. Am J Physiol. 1987 Aug;253(2 Pt 1):C243–C252. doi: 10.1152/ajpcell.1987.253.2.C243. [DOI] [PubMed] [Google Scholar]
- Hoyer J. R., Sisson S. P., Vernier R. L. Tamm-Horsfall glycoprotein: ultrastructural immunoperoxidase localization in rat kidney. Lab Invest. 1979 Aug;41(2):168–173. [PubMed] [Google Scholar]
- Igarashi P., Vanden Heuvel G. B., Payne J. A., Forbush B., 3rd Cloning, embryonic expression, and alternative splicing of a murine kidney-specific Na-K-Cl cotransporter. Am J Physiol. 1995 Sep;269(3 Pt 2):F405–F418. doi: 10.1152/ajprenal.1995.269.3.F405. [DOI] [PubMed] [Google Scholar]
- Kaplan M. R., Plotkin M. D., Lee W. S., Xu Z. C., Lytton J., Hebert S. C. Apical localization of the Na-K-Cl cotransporter, rBSC1, on rat thick ascending limbs. Kidney Int. 1996 Jan;49(1):40–47. doi: 10.1038/ki.1996.6. [DOI] [PubMed] [Google Scholar]
- Knepper M., Burg M. Organization of nephron function. Am J Physiol. 1983 Jun;244(6):F579–F589. doi: 10.1152/ajprenal.1983.244.6.F579. [DOI] [PubMed] [Google Scholar]
- Lapointe J. Y., Bell P. D., Cardinal J. Direct evidence for apical Na+:2Cl-:K+ cotransport in macula densa cells. Am J Physiol. 1990 May;258(5 Pt 2):F1466–F1469. doi: 10.1152/ajprenal.1990.258.5.F1466. [DOI] [PubMed] [Google Scholar]
- Lapointe J. Y., Laamarti A., Hurst A. M., Fowler B. C., Bell P. D. Activation of Na:2Cl:K cotransport by luminal chloride in macula densa cells. Kidney Int. 1995 Mar;47(3):752–757. doi: 10.1038/ki.1995.115. [DOI] [PubMed] [Google Scholar]
- Obermüller N., Bernstein P., Velázquez H., Reilly R., Moser D., Ellison D. H., Bachmann S. Expression of the thiazide-sensitive Na-Cl cotransporter in rat and human kidney. Am J Physiol. 1995 Dec;269(6 Pt 2):F900–F910. doi: 10.1152/ajprenal.1995.269.6.F900. [DOI] [PubMed] [Google Scholar]
- Payne J. A., Forbush B., 3rd Alternatively spliced isoforms of the putative renal Na-K-Cl cotransporter are differentially distributed within the rabbit kidney. Proc Natl Acad Sci U S A. 1994 May 10;91(10):4544–4548. doi: 10.1073/pnas.91.10.4544. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sanger F., Nicklen S., Coulson A. R. DNA sequencing with chain-terminating inhibitors. Proc Natl Acad Sci U S A. 1977 Dec;74(12):5463–5467. doi: 10.1073/pnas.74.12.5463. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schlatter E., Salomonsson M., Persson A. E., Greger R. Macula densa cells sense luminal NaCl concentration via furosemide sensitive Na+2Cl-K+ cotransport. Pflugers Arch. 1989 Jul;414(3):286–290. doi: 10.1007/BF00584628. [DOI] [PubMed] [Google Scholar]
- Wilcox C. S., Welch W. J., Murad F., Gross S. S., Taylor G., Levi R., Schmidt H. H. Nitric oxide synthase in macula densa regulates glomerular capillary pressure. Proc Natl Acad Sci U S A. 1992 Dec 15;89(24):11993–11997. doi: 10.1073/pnas.89.24.11993. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Xu J. C., Lytle C., Zhu T. T., Payne J. A., Benz E., Jr, Forbush B., 3rd Molecular cloning and functional expression of the bumetanide-sensitive Na-K-Cl cotransporter. Proc Natl Acad Sci U S A. 1994 Mar 15;91(6):2201–2205. doi: 10.1073/pnas.91.6.2201. [DOI] [PMC free article] [PubMed] [Google Scholar]