Effects of norepinephrine on expression of IGF-1/IGF-1R and SERCA2 in rat heart.
OBJECTIVE
The effects of norepinephrine on expression of cardiac genes during pathological cardiac growth and heart failure are not fully understood. Tissue insulin-like growth factor 1 (IGF-1) and its receptor (IGF-1R) play an important role in the regulation of the hyperplastic capacity of cardiac myocytes. Sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2), on the other hand, is important in regulating cardiac contractile function. The present study examined the effects of elevated levels of NE on expression of IGF-1/IGF-1R and SERCA2 mRNAs.


METHODS
Rats were infused with NE using osmotic minipumps for 3 and 6 days at a rate of 50 micrograms/kg/h and also at a higher dose (130 micrograms/kg/h) for 6 and 14 days. Levels of expression of IGF-1/IGF-1R and SERCA2 mRNAs were determined by ribonuclease protection assay and by Northern blotting, respectively.


RESULTS
NE treatment significantly increased IGF-1 mRNA levels in both left- and right-ventricle; however, levels of IGF-1R increased in the left- but not the right-ventricle. By contrast, NE infusion at both the lower dose and the higher dose failed to alter expression of SERCA2 mRNA.


CONCLUSIONS
Our results suggest that NE treatment differentially regulates expression of IGF-1 and IGF-1R in the ventricles of rat heart and that NE appears not to affect expression of SERCA2 mRNA.
Sun
X
X
Department of Pharmacology, College of Medicine, Pennsylvania State University, Hershey 17033, USA.
Ng
Y C
YC
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000818:Animals; D015152:Blotting, Northern; D000252:Calcium-Transporting ATPases / Q000235:genetics*; D015870:Gene Expression / Q000187:drug effects; D005821:Genetic Techniques; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D016014:Linear Models; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017526:Receptor, IGF Type 1 / Q000235:genetics*
D000316:Adrenergic alpha-Agonists; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1; D000252:Calcium-Transporting ATPases; D009638:Norepinephrine