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Lookup NU author(s): John Linley,
Professor Nicholas Simmons,
Dr Michael Gray
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We have used the perforated patch clamp and fura-2 fluorescence techniques to study the effect of extracellular Zn2+ on whole-cell Ca 2+-activated Cl- currents (I CLCA) in mouse inner medullary collecting duct cells (mIMCD-3). I CLCA was spontaneously active in 74% of cells under basal conditions and displayed time and voltage-independent kinetics and an outwardly rectifying current/voltage relationship (I/V). Addition of zinc chloride (10-400 μM) to the bathing solution resulted in a dose-dependent increase in I CLCA with little change in Cl- selectivity or biophysical characteristics, whereas gadolinium chloride (30 μM) and lanthanum chloride (100 μM) had no significant effect on the whole-cell current. Using fura-2-loaded mIMCD-3 cells, extracellular Zn2+ (400 μM) stimulated an increase in intracellular Ca2+ to an elevated plateau. The Zn2+- stimulated [Ca2+]i increase was inhibited by thapsigargin (200 nM), the IP3 receptor antagonist 2-aminoethoxydiphenyl borate (10 μM) and removal of bath Ca2+. Pre-exposure to Zn2+ (400 μM) markedly attenuated the ATP (100 μM)-stimulated [Ca 2+]i increase. These data are consistent with the hypothesis that extracellular Zn2+ stimulates an increase in [Ca 2+]i by a release of calcium from thapsigargin/IP 3 sensitive stores. A possible physiological role for a divalent metal ion receptor, distinct from the extracellular Ca2+-sensing receptor, in IMCD cells is discussed. © 2006 Springer-Verlag.
Author(s): Linley JE, Simmons NL, Gray MA
Publication type: Article
Publication status: Published
Journal: Pflugers Archiv European Journal of Physiology
Print publication date: 01/01/2007
ISSN (print): 0031-6768
ISSN (electronic): 1432-2013
PubMed id: 17021797
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