Riccardi, D; Traebert, M; Ward, D T; Kaissling, B; Biber, J; Hebert, S C; Murer, H (2000). 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 Archiv: European Journal of Physiology (Pflugers Archiv), 441(2-3):379-387.
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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:||Journal Article, refereed|
|Communities & Collections:||04 Faculty of Medicine > Institute of Physiology|
07 Faculty of Science > Institute of Physiology
|DDC:||570 Life sciences; biology|
|Date:||01 December 2000|
|Deposited On:||11 Feb 2008 13:23|
|Last Modified:||23 Nov 2012 14:07|
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