Contractile response of norepinephrine is modulated by caspase-3 in adult rat ventricular myocytes isolated from septic rat heart

Pharmacol Res. 2009 Oct;60(4):303-13. doi: 10.1016/j.phrs.2009.04.009. Epub 2009 Apr 24.

Abstract

Sepsis accounts for 50% of intensive care unit deaths due to cardiac dysfunction. The cellular mechanisms following norepinephrine (NE) during sepsis are undefined. Using a septic adult rat ventricular myocyte (ARVM) paradigm, we examined the molecular mechanism responsible for the blunted contractile response of NE. We tested the hypothesis that NE-induced increases in active caspase-3 contribute to sepsis-induced ARVM contractile dysfunction. Single ARVMs were isolated from hearts harvested from sham and septic male rats. The contractile properties and expression of caspase-3 cascade proteins were determined in ARVMs treated with NE with and without QVD-OPH, prazosin and atenolol to characterize the effect of NE on their mechanical properties. Septic ARVMs exhibited a significant decrease in peak shortening (PS) compared to sham ARVMs. The effect of NE on the PS of the sham ARVMs was more pronounced compared to the septic ARVMs, suggesting a blunted contractile response of NE. NE in the presence of QVD-OPH ameliorated the sepsis-induced decrease in PS at 18h but not at 1h, while the effect of NE on sepsis-induced contractile response remained unaffected at 18h by prazosin and atenolol. An up-regulated expression of caspase-3 in NE-treated septic ARVMs was reversed by QVD-OPH, as seen by the increased number of septic ARVMs exhibiting caspase-3 fluorescence. Transfection of ARVMs using caspase-3 siRNA blocked sepsis-induced up-regulation of caspase-3 and increased PS following NE treatment. These data suggest that caspase-3 inhibition ameliorated sepsis-induced decreased ARVM contractility and blocked the blunted contractile response of NE.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic alpha-Agonists / pharmacology*
  • Amino Acid Chloromethyl Ketones / pharmacology
  • Animals
  • Apoptosis / drug effects
  • Atenolol / pharmacology
  • Caspase 3 / genetics
  • Caspase 3 / metabolism*
  • Cells, Cultured
  • Gene Expression / drug effects
  • Male
  • Myocardial Contraction / drug effects*
  • Myocytes, Cardiac / drug effects*
  • Myocytes, Cardiac / pathology
  • Norepinephrine / pharmacology*
  • Prazosin / pharmacology
  • Quinolines / pharmacology
  • Rats
  • Rats, Sprague-Dawley
  • Sepsis / chemically induced
  • Sepsis / physiopathology*

Substances

  • Adrenergic alpha-Agonists
  • Amino Acid Chloromethyl Ketones
  • Quinolines
  • quinoline-val-asp(OMe)-CH2-OPH
  • Atenolol
  • Caspase 3
  • Norepinephrine
  • Prazosin