Dietary phosphate and parathyroid hormone alter the expression of the calcium-sensing receptor (CaR) and the Na + -dependent P i transporter (NaPi-2) in the rat proximal tubule

Riccardi, Daniela ORCID: https://orcid.org/0000-0002-7322-3163, Traebert, Martin, Ward, Donald T., Kaissling, Brigitte, Biber, J., Hebert, Steven C. and Murer, Heini 2000. Dietary phosphate and parathyroid hormone alter the expression of the calcium-sensing receptor (CaR) and the Na + -dependent P i transporter (NaPi-2) in the rat proximal tubule. Pflugers Archiv European Journal of Physiology 441 (2-3) , pp. 379-387. 10.1007/s004240000436

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Abstract

Dietary phosphate (Pi) intake and parathyroid hormone (PTH) are essential regulators of proximal tubular (PT) Pi reabsorption; both factors are associated with adaptive changes in PT apical brush border membrane (BBM) Na/Pi-cotransport activity and specific transporter protein (NaPi-2) content. Urinary Pi excretion is also inversely correlated with luminal Ca2+ concentration ([Ca2+]) both in a PTH-dependent and -independent fashion. A cell-surface, Ca2+(/polyvalent cation)-sensing receptor (CaR) has been localized to the PT BBM with unknown function. To investigate whether PTH and/or dietary Pi intake could affect the distribution or the expression of the CaR, we evaluated their effects on rat kidney CaR and the NaPi-2 expression by Western blot analysis and immunofluorescence microscopy. A chronic high-Pi (1.2%) versus low-Pi (0.1%) diet and acute PTH (1–34) infusion significantly reduced the PT BBM expression of both NaPi-2 and CaR proteins. CaR-specific immunoreactivity in nephron segments other than the PT was not affected by PTH or Pi intake. These results suggest that reduced renal PT CaR expression by a high-Pi diet and by increased circulating PTH levels could contribute to the local control of PT handling of Ca2+ and Pi.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Biosciences
Publisher:	Springer
ISSN:	0031-6768
Last Modified:	27 Oct 2022 08:49
URI:	https://orca.cardiff.ac.uk/id/eprint/63473

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