Reciprocal changes in the postnatal expression of the sarcolemmal Na+-Ca(2+)-exchanger and SERCA2 in rat heart.
The aim of this study was to examine the relationship between sarcolemmal Na(+)-Ca2+ exchangers and sarcoplasmic reticulum (SR) Ca(2+) -ATPase (SERCA2) expression and the developmental differences in cardiac Ca2+ handling. Postnatal steady-state mRNA and protein levels were analysed in rat ventricular myocardium by Northern and immunoblot analysis, respectively. This was compared to Na+ gradient-induced and SR oxalate-supported Ca2 transport in isolated membranes. Na(+)-Ca2+ exchanger mRNA declined by 75% between day 1 and 30, whereas SR Ca2+ ATPase mRNA levels increased by 97% during this period. The Na(+)-Ca2+ exchanger mRNA/Ca(2+)-ATPase mRNA ratio was found to be inversely related to post-natal age. The changes in mRNA levels were associated with corresponding developmental differences in the Ca2+ transport activities of the respective membrane proteins. In crude membranes, the Na(+)-dependent Ca2+ transport activity (at 75 microM Ca2+) declined gradually (P < 0.01; mean +/- S.E.) from 17.7 +/- 2.4 nmoles Ca2+/g wet tissue/2s at day 1-3 (n = 5) to a value of 4.2 +/- 1.1 at day 40 (n =4). Conversely, SR Ca2+ uptake increased (P < 0.01) 2.6-fold during this period. The inversely related changes in the post-natal expression and function of the Na(+)-Ca2+ exchanger and SR Ca(2+)-ATPase suggest a coordinated control at the pretranslational level of the cellular Ca2+ transport processes mediated by the two membrane proteins.
Max Delbrück Center for Molecular Medicine, Berlin-Buch, Germany.
R
R
Vetter
R
R
Studer
H
H
Reinecke
F
F
Kolár
I
I
Ostádalová
H
H
Drexler
D000375:Aging / Q000378:metabolism*; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000096:biosynthesis; D002352:Carrier Proteins / Q000096:biosynthesis*; D015870:Gene Expression; D006321:Heart / Q000254:growth & development / Q000502:physiology*; D006339:Heart Rate; D066298:In Vitro Techniques; D009206:Myocardium / Q000378:metabolism*; D010070:Oxalates / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012508:Sarcolemma / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D019831:Sodium-Calcium Exchanger; D013599:Systole
D002352:Carrier Proteins; D010070:Oxalates; D012333:RNA, Messenger; D019831:Sodium-Calcium Exchanger; D000252:Calcium-Transporting ATPases; D002118:Calcium