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.
Similar content being viewed by others
Author information
Authors and Affiliations
Additional information
Received after revision: 2 August 2000
Electronic Publication
Rights and permissions
About this article
Cite this article
Riccardi, D., Traebert, M., Ward, D. et al. Dietary phosphate and parathyroid hormone alter the expression of the calcium-sensing receptor (CaR) and the Na+-dependent Pi transporter (NaPi-2) in the rat proximal tubule. Pflügers Arch - Eur J Physiol 441, 379–387 (2000). https://doi.org/10.1007/s004240000436
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/s004240000436