Expression of the Na(+)/Ca(2+) exchanger in skeletal muscle.
The expression of the Na(+)/Ca(2+) exchanger was studied in differentiating muscle fibers in rats. NCX1 and NCX3 isoform (Na(+)/Ca(2+) 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.
Fraysse
B
B
Faculté des Sciences et des Techniques, Université de Nantes, Nantes Cedex 3, France.
Rouaud
T
T
Millour
M
M
Fontaine-Pérus
J
J
Gardahaut
M F
MF
Levitsky
D O
DO
D000367:Age Factors; D000818:Animals; D002451:Cell Compartmentation / Q000502:physiology; D002454:Cell Differentiation / Q000235:genetics*; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D008297:Male; D026901:Membrane Transport Proteins; D024510:Muscle Development; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000254:growth & development* / Q000378:metabolism* / Q000648:ultrastructure; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011921:Rats, Inbred WKY; D019831:Sodium-Calcium Exchanger / Q000235:genetics* / Q000378:metabolism
D026901:Membrane Transport Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; C110927:Slc8a2 protein, rat; C491102:Slc8a3 protein, rat; D019831:Sodium-Calcium Exchanger; C110374:sodium-calcium exchanger 1