Calcium reabsorption in the distal tubule: regulation by sodium, pH, and flow.

Details

Serval ID
serval:BIB_9C6D71787642
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Calcium reabsorption in the distal tubule: regulation by sodium, pH, and flow.
Journal
American Journal of Physiology.
Author(s)
Bonny O., Edwards A.
ISSN
1522-1466 (Electronic)
ISSN-L
1522-1466
Publication state
Published
Issued date
2013
Volume
304
Number
5
Pages
F585-F600
Language
english
Abstract
We developed a mathematical model of Ca transport along the late distal convoluted tubule (DCT2) and the connecting tubule (CNT) to investigate the mechanisms that regulate Ca reabsorption in the DCT2-CNT. The model accounts for apical Ca influx across transient receptor potential vanilloid 5 (TRPV5) channels and basolateral Ca efflux via plasma membrane Ca-ATPase pumps and type 1 Na/Ca exchangers (NCX1). Model simulations reproduce experimentally observed variations in Ca uptake as a function of extracellular pH, Na, and Mg concentration. Our results indicate that amiloride enhances Ca reabsorption in the DCT2-CNT predominantly by increasing the driving force across NCX1, thereby stimulating Ca efflux. They also suggest that because aldosterone upregulates both apical and basolateral Na transport pathways, it has a lesser impact on Ca reabsorption than amiloride. Conversely, the model predicts that full NCX1 inhibition and parathyroidectomy each augment the Ca load delivered to the collecting duct severalfold. In addition, our results suggest that regulation of TRPV5 activity by luminal pH has a small impact, per se, on transepithelial Ca fluxes; the reduction in Ca reabsorption induced by metabolic acidosis likely stems from decreases in TRPV5 expression. In contrast, elevations in luminal Ca are predicted to significantly decrease TRPV5 activity via the Ca-sensing receptor. Nevertheless, following the administration of furosemide, the calcium-sensing receptor-mediated increase in Ca reabsorption in the DCT2-CNT is calculated to be insufficient to prevent hypercalciuria. Altogether, our model predicts complex interactions between calcium and sodium reabsorption in the DCT2-CNT.
Pubmed
Web of science
Create date
12/04/2013 18:46
Last modification date
20/10/2020 11:08
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