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Title: Extracellular Ca2+ regulates the stimulation of Na+ transport in A6 renal epithelia
Authors: Jans, Danny ×
Simaels, Jeannine
Larivière, Els
Steels, Paul
Van Driessche, Willy #
Issue Date: Sep-2004
Series Title: American journal of physiology. Renal physiology. vol:287 issue:4 pages:F840-9
Abstract: We investigated the involvement of intracellular and extracellular Ca2+ in the stimulation of Na+ transport during hyposmotic treatment of A6 renal epithelia. A sudden osmotic decrease elicits a biphasic stimulation of Na+ transport, recorded as increase in amiloride-sensitive short-circuit current (Isc) from 3.4 +/- 0.4 to 24.0 +/- 1.3 microA/cm2 (n = 6). Changes in intracellular Ca2+ concentration ([Ca2+]i) were prevented by blocking basolateral Ca2+ entry with Mg2+ and emptying the intracellular Ca2+ stores before the hyposmotic challenge. This treatment did not noticeably affect the hypotonicity-induced stimulation of Isc. However, the absence of extracellular Ca2+ severely attenuated Na+ transport stimulation by the hyposmotic shock, and Isc merely increased from 2.2 +/- 0.3 to 4.8 +/- 0.7 microA/cm2. Interestingly, several agonists of the Ca2+-sensing receptor, Mg2+ (2 mM), Gd3+ (0.1 mM), neomycin (0.1 mM), and spermine (1 mM) were able to substitute for extracellular Ca2+. When added to the basolateral solution, these agents restored the stimulatory effect of the hyposmotic solutions on Isc in the absence of extracellular Ca2+ to levels that were comparable to control conditions. None of the above-mentioned agonists induced a change in [Ca2+]i. Quinacrine, an inhibitor of PLA2, overruled the effect of the agonists on Na+ transport. In conclusion, we suggest that a Ca2+-sensing receptor in A6 epithelia mediates the stimulation of Na+ transport without the interference of changes in [Ca2+]i.
URI: 
ISSN: 0363-6127
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Physiology Section (-)
Laboratory of Cellular Transport Systems
Department of Cellular and Molecular Medicine - miscellaneous
Biomedical Sciences Teaching Methodology and Practicals
× corresponding author
# (joint) last author

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