Extracellular Mg2+ regulates the intracellular Na+ concentration in rat sublingual acini
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Updated: Nov 1, 2026

Single-channel Analysis and Calcium Imaging in the Podocytes of the Freshly Isolated Glomeruli
Published on: June 27, 2015
1Department of Dental Research, University of Rochester Medical Center, NY 14642, USA.
Abstract:
The intracellular free Na+ concentration ([Na+]i) increases during muscarinic stimulation in salivary acinar cells. The present study examined in rat sublingual acini the role of extracellular Mg2+ in the regulation of the stimulated [Na+]i increase using the fluorescent sodium indicator benzofuran isophthalate (SBFI). The muscarinic induced rise in [Na+]i was approximately 4-fold greater in the absence of extracellular Mg2+. When Na+ efflux was blocked by the Na+,K+-ATPase inhibitor ouabain, the stimulated [Na+]i increase was comparable to that seen in an Mg2+-free medium. Moreover, ouabain did not add further to the stimulated [Na+]i increase in an Mg2+-free medium suggesting that removal of extracellular Mg2+ may inhibit the Na+ pump. In agreement with this assumption, ouabain-sensitive Na+ efflux and rubidium uptake were reduced by extracellular Mg2+ depletion. Our results suggest that extracellular Mg2+ may regulate [Na+]i in sublingual salivary acinar cells by modulating Na+ pump activity.
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