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Homozygous Overexpression of the Na + ‐Ca 2+ Exchanger in Mice
Author(s) -
POTT CHRISTIAN,
GOLDHABER JOSHUA I.,
PHILIPSON KENNETH D.
Publication year - 2007
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1196/annals.1387.019
Subject(s) - microbiology and biotechnology , chemistry , physics , radiochemistry , biology
Mice with homozygous overexpression of the Na + ‐Ca 2+ exchanger (NCX) exhibit threefold levels of NCX expression and an increased Ca 2+ extrusion rate. To investigate how Ca 2+ homeostasis is maintained in this model, we have characterized Ca 2+ influx under these conditions. We find that L‐type Ca 2+ currents (I Ca ) inactivate slower due to a reduction of Ca 2+ ‐dependent inactivation. Additionally, NCX‐overexpressing animals exhibit a prolongation of the action potential (AP). We conclude that transsarcolemmal Ca 2+ fluxes in NCX‐overexpressing myocytes are balanced by an increase in Ca 2+ influx via (a) slowed inactivation of I Ca and (b) a prolongation of the AP to compensate for increased Ca 2+ efflux.