title: Endogenous endothelium-derived nitric oxide inhibits myocardial caspase activity: implications for treatment of end-stage heart failure.
abstract: BACKGROUND
  Apoptosis contributes to ventricular remodeling in heart failure (HF). Nitric oxide (NO) inhibits caspase 3, a key effector apoptotic enzyme. We hypothesized that reduced endogenous NO in HF disinhibits cardiac caspase 3 to promote apoptosis.
  
  
  METHODS
  Caspase 3 activity was measured colorimetrically in myocardial cell lysates from endothelial NO synthase (eNOS)-deficient mice (eNOS -/-; n = 18), cardiomyopathic (CMP) hamsters (n = 8), and explanted failing human hearts (n = 10). We stimulated myocardial caspase 3 activity by adding upstream caspase 8 or 9. Cell lysates were incubated with 10(-4) mol/liter NO donor, S-nitroso-N-acetyl penicillamine; NOS inhibitor, nitro-L-arginine-methyl ester (L-NAME); or angiotensin-converting enzyme (ACE) inhibitor, enalaprilat. Hamsters underwent echocardiography so we could study the progression of ventricular dysfunction.
  
  
  RESULTS
  Stimulated caspase 3 activity was lower in myocardium of eNOS +/+ compared with eNOS -/- mouse hearts (5.1 +/- 0.5 vs 7.6 +/- 1.0 pmol/10 microg/min, p < 0.05). L-NAME increased enzyme activity only in eNOS +/+ mice, indicating that endogenous NO inhibits caspase 3. Stimulated caspase 3 activity was lower in control hamsters, 3.3 +/- 0.3 pmol/10 microg/min, compared with CMP hamsters, 9.6 +/- 0.7 and 6.9 +/- 0.4 pmol/10 microg/min at 4 and 9 months, respectively. This was associated with progressive ventricular dysfunction, thinning, and dilatation. L-NAME increased enzyme activity in normal but not in CMP hamsters. In failing human myocardium, L-NAME failed to alter caspase activity, indicating reduced NO availability. Enalaprilat inhibited caspase 3, which was reversed by L-NAME. S-nitroso-N-acetyl penicillamine reversed caspase 3 activation in all groups.
  
  
  CONCLUSIONS
  Nitric oxide reversibly inhibits myocardial caspase 3 independent of the apoptotic signaling pathway. Reduced NO in HF increases myocardial caspase 3 activity. Agents that promote NO synthesis, including ACE inhibitors, may prevent caspase activation in HF.
authors: Division of Pediatric Cardiology, Babies Hospital, Columbia University, New York, New York 10032, USA. sm364@columbia.edu
authors: Seema
authors: S
authors: Mital
authors: Alessandro
authors: A
authors: Barbone
authors: Linda J
authors: LJ
authors: Addonizio
authors: Jan M
authors: JM
authors: Quaegebeur
authors: Ralph J
authors: RJ
authors: Mosca
authors: Mehmet C
authors: MC
authors: Oz
authors: Thomas H
authors: TH
authors: Hintze
mesh_terms: D000818:Animals; D017209:Apoptosis; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D006224:Cricetinae; D004730:Endothelium, Vascular / Q000378:metabolism*; D005260:Female; D006333:Heart Failure / Q000503:physiopathology*; D051379:Mice; D008822:Mice, Transgenic; D009206:Myocardium / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000502:physiology*; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D020257:Ventricular Remodeling
chemical_list: D061945:Caspase Inhibitors; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases