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Phenylephrine hypertrophy, Ca2+-ATPase (SERCA2), and Ca2+ signaling in neonatal rat cardiac myocytes.
Phenylephrine hypertrophy, Ca2+-ATPase (SERCA2), and Ca2+ signaling in neonatal rat cardiac myocytes.
- Source :
-
American journal of physiology. Cell physiology [Am J Physiol Cell Physiol] 2007 Jun; Vol. 292 (6), pp. C2269-75. Date of Electronic Publication: 2007 Feb 07. - Publication Year :
- 2007
-
Abstract
- We endeavored to use a basic and well-controlled experimental system to characterize the extent and time sequence of sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) involvement in the development of cardiac hypertrophy, including transcription, protein expression, Ca(2+) transport, and cytoplasmic Ca(2+) signaling. To this end, hypertrophy of neonatal rat cardiac myocytes in culture was obtained after adrenergic activation with phenylephrine (PE). Micrographic assessment of myocyte size, rise of [(14)C]phenylalanine incorporation and total protein expression, and increased transcription of atrial natriuretic factor demonstrated unambiguously the occurrence of hypertrophy. An early and prominent feature of hypertrophy was a reduction of the SERCA2 transcript, as determined by RT-PCR with reference to a stable marker such as glyceraldehyde-3-phosphate dehydrogenase. Reduction of Ca(2+)-ATPase protein levels and Ca(2+) transport activity to approximately 50% of control values followed with some delay, evidently as a consequence of a primary effect on transcription. Cytosolic Ca(2+) signaling kinetics, measured with a Ca(2+)-sensitive dye after electrical stimuli, were significantly altered in hypertrophic myocytes. However, the effect of PE hypertrophy on cytosolic Ca(2+) signaling kinetics was less prominent than observed in myocytes subjected to drastic SERCA2 downregulation with small interfering RNA or inhibition with thapsigargin (10 nM). We conclude that SERCA2 undergoes significant downregulation after hypertrophic stimuli, possibly due to lack of SERCA gene involvement by the hypertrophy transcriptional program. The consequence of SERCA2 downregulation on Ca(2+) signaling is partially compensated by alternate Ca(2+) transport mechanisms. These alterations may contribute to a gradual onset of functional failure in long-term hypertrophy.
- Subjects :
- Animals
Animals, Newborn
Cardiotonic Agents pharmacology
Cells, Cultured
Cytosol metabolism
Dose-Response Relationship, Drug
Down-Regulation
Gene Expression Regulation, Enzymologic
Gene Silencing
Phenylephrine toxicity
Rats
Thapsigargin
Time Factors
Calcium Signaling
Cardiomegaly chemically induced
Myocytes, Cardiac metabolism
Phenylephrine pharmacology
Sarcoplasmic Reticulum Calcium-Transporting ATPases metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0363-6143
- Volume :
- 292
- Issue :
- 6
- Database :
- MEDLINE
- Journal :
- American journal of physiology. Cell physiology
- Publication Type :
- Academic Journal
- Accession number :
- 17287366
- Full Text :
- https://doi.org/10.1152/ajpcell.00441.2006