Key result
Alpha 2-isoform knockout in VSMCs abolishes the normal ~90% Ca2+ clearance by NCX.
Why the study?
The role of the Na+-K+-ATPase alpha 2-isoform in modulating Ca2+ storage and clearance via coupling to the Na+-Ca2+ exchanger in vascular smooth muscle cells was unclear.
Population
Aortic vascular smooth muscle cells from embryonic wild-type and Na+-K+-ATPase alpha 2-isoform gene-ablated mice
Comparison
Na+-K+-ATPase alpha 2-isoform gene ablation and selective inhibition with 0.5 microM ouabain vs wild-type
Design
Preclinical experimental study
Authors
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α2-Na+-K+-ATPase loss impairs NCX-mediated Ca2+ clearance in VSMCs; leaves open relevance to adult vascular tone or disease.
The study demonstrates that the Na+-K+-ATPase alpha 2-isoform couples with the Na+-Ca2+ exchanger in a subsarcolemmal space to modulate Ca2+ storage and clearance in vascular smooth muscle cells.
Lynch et al. (2008) studied this question. Na+-K+-ATPase alpha 2-isoform gene ablation vs. Wild-type (WT) mice was evaluated on Ca2+ clearance by the Na+-Ca2+ exchanger (NCX). In wild-type vascular smooth muscle cells, NCX accounted for 90% of Ca2+ efflux, whereas this preferential clearance of store-released Ca2+ by NCX was lost in alpha 2-isoform knockout cells.
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