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The ouabain-sensitive isoform of Na+-pump regulates vascular gap junctions via interaction with the Na+/Ca2+-exchanger in membrane microdomain

Research output: Contribution to conferencePosterResearch

  • Department of Physiology and Biophysics

Ouabain, an inhibitor of the Na+-pump, has been shown to inhibit intercellular communication. We have recently shown that gap junctions between vascular smooth muscle cells (SMCs) are regulated through an interaction between a ouabain-sensitive isoform of the Na+-pump and the Na+/Ca2+-exchanger leading to increases in [Ca2+]i in discrete areas near the plasma membrane. This suggests close association of these transport proteins in microdomains.

Using PCR and co-immunoprecipitation we aimed to test this hypothesis in SMCs from mesenteric small arteries and in A7r5 cell line. Intercellular electrical coupling was evaluated in functional studies.

SMCs were electrically uncoupled when the ouabain-sensitive Na+-pump was inhibited by 10 mM ouabain. Inhibition of the Na+/Ca2+-exchanger with 1 mM SEA0400 also uncoupled the SMCs. Depletion of [Na+]i and clamping [Ca2+]i at low levels prevented the uncoupling. Ten mM ouabain evoked spatially restricted [Ca2+]i transients along the cell periphery but not in the center of the cell.

mRNA for all three isoforms of the Na+-pump α subunit were found in SMCs but only ouabain-sensitive α2 subunit was specifically co-immunoprecipitated with the Na+/Ca2+-exchanger-1 and connexin-43. The α3 Na+-pump subunit was not associated with these proteins but co-immunoprecipitated with caveolin-1. Based on these experiments we suggest that α2 Na+ -pump subunit is involved in regulation of the intercellular communication via interaction with the Na+/Ca2+-exchanger-1 leading to local [Ca2+]i transients near the membrane which block the closely associated connexin-43 containing gap junctions.
Original languageEnglish
Publication year2008
Number of pages1
Publication statusPublished - 2008
Event13th Annual Meeting of the European Council of Cardiovascular Research - Nice, France
Duration: 10 Oct 200812 Oct 2008
Conference number: 13


Conference13th Annual Meeting of the European Council of Cardiovascular Research

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