Vol. 280, Issue 1, C146-C154, January 2001
Expression of the Na+/Ca2+
exchanger in skeletal muscle
Bodvaël
Fraysse*,
Thierry
Rouaud*,
Marie
Millour,
Josiane
Fontaine-Pérus,
Marie-France
Gardahaut, and
Dmitri O.
Levitsky
Faculté des Sciences et des Techniques, Université de
Nantes, Nantes Cedex 3, France
The expression of the
Na+/Ca2+ exchanger was studied in
differentiating muscle fibers in rats. NCX1 and NCX3 isoform
(Na+/Ca2+ exchanger isoform) expression was
found to be developmentally regulated. NCX1 mRNA and protein levels
peaked shortly after birth. Conversely, NCX3 isoform expression was
very low in muscles of newborn rats but increased dramatically during
the first 2 wk of postnatal life. Immunocytochemical analysis showed
that NCX1 was uniformly distributed along the sarcolemmal membrane of
undifferentiated rat muscle fibers but formed clusters in T-tubular
membranes and sarcolemma of adult muscle. NCX3 appeared to be more
uniformly distributed along the sarcolemma and inside myoplasm. In the
adult, NCX1 was predominantly expressed in oxidative (type 1 and 2A) fibers of both slow- and fast-twitch muscles, whereas NCX3 was highly
expressed in fast glycolytic (2B) fibers. NCX2 was expressed in rat
brain but not in skeletal muscle. Developmental changes in NCX1 and
NCX3 as well as the distribution of these isoforms at the cellular
level and in different fiber types suggest that they may have different
physiological roles.
sodium/calcium exchanger isoforms; gene expression
*
B. Fraysse and T. Rouaud contributed equally to this work.
