Enhanced SERCA2A expression improves contractile performance of ventricular cardiomyocytes of rat under adrenergic stimulation

Pflugers Arch. 2008 Nov;457(2):485-91. doi: 10.1007/s00424-008-0520-7. Epub 2008 Jun 26.

Abstract

alpha-Adrenergic stimulation results in a positive adaptation of cardiomyocytes to increased cardiac work load by induction of hypertrophy and enhanced contraction. However, sustained adrenergic stimulation causes progression to heart failure. Under simultaneous activation of alpha- and beta-adrenoceptors by the naturally occurring catecholamine noradrenaline, beta1-stimulation inhibits alpha-adrenergic-stimulated hypertrophy. If beta-adrenergic stimulation may also influence cardiomyocyte contraction is not known yet. We now demonstrate that exposure of cardiomyocytes to noradrenaline or isoprenaline for 24 h results in a reduced cell shortening at low beating frequencies (0.5 Hz). At high beating frequencies (2 Hz), cell shortening was normal. beta-adrenergic stimulation enhances SERCA2A expression at the messenger RNA and protein level. This induction of the Ca(2+) pump SERCA2A by the transcription factor NFAT is responsible for maintenance of normal cell contraction at high beating frequencies since inhibition of NFAT by decoy-oligonucleotides impairs SERCA2A expression and cell shortening after beta-adrenergic stimulation. In conclusion, although reduced cell shortening is found under low beating frequencies, we demonstrate preservation of cardiomyocyte contraction at 2 Hz after exposure to beta-adrenergic stimuli, which indicate that adrenergic stimulation a priori does not cause impaired heart function. The increase of SERCA expression indicates an even improved Ca(2+) handling of the cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic alpha-Agonists / pharmacology*
  • Adrenergic beta-Agonists / pharmacology*
  • Animals
  • Calcium / metabolism
  • Cardiac Pacing, Artificial
  • Cardiotonic Agents / pharmacology*
  • Cells, Cultured
  • Enzyme Induction
  • Heart Rate
  • Heart Ventricles / drug effects
  • Heart Ventricles / enzymology
  • Isoproterenol / pharmacology*
  • Male
  • Myocardial Contraction / drug effects*
  • Myocytes, Cardiac / drug effects*
  • Myocytes, Cardiac / enzymology
  • NFATC Transcription Factors / metabolism
  • Norepinephrine / pharmacology*
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Wistar
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases / biosynthesis*
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases / genetics
  • Time Factors

Substances

  • Adrenergic alpha-Agonists
  • Adrenergic beta-Agonists
  • Atp2a2 protein, rat
  • Cardiotonic Agents
  • NFATC Transcription Factors
  • RNA, Messenger
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases
  • Isoproterenol
  • Calcium
  • Norepinephrine