Comparison of the effects of an angiotensin-converting enzyme inhibitor and a vasopeptidase inhibitor after myocardial infarction in the rat.
OBJECTIVE
The goal of this study was to compare the effects of the vasopeptidase inhibitor omapatrilat and the angiotensin-converting enzyme inhibitor (ACEI) captopril in the postmyocardial infarction (MI) rat model. BACKGROUND; The cardioprotective effects of ACEIs after MI are thought to be partially due to an increase in bradykinin (BK). Vasopeptidase inhibitors inhibit both ACE and neutral endopeptidase (NEP), further reduce BK metabolism and increase natriuretic peptides, which may result in better cardioprotective effects than with ACEIs after MI.


METHODS
Myocardial infarction was induced in 514 Wistar male rats by ligation of the anterior coronary artery. Rats surviving 4 h after MI (n = 282) were assigned to omapatrilat (40 or 80 mg/kg/day), captopril (160 mg/kg/day) or no treatment. After 56 days, neurohumoral, hemodynamic, ventricular remodeling, morphometry, immunohistochemistry and cardiac cytokine expression were measured.


RESULTS
Omapatrilat and captopril resulted in similarly improved survival, cardiac hemodynamics and reduced cardiac fibrosis and hypertrophy after MI. The pattern of left ventricular (LV) remodeling differed, omapatrilat causing less attenuation of the rightward shift of the LV pressure-volume relation at lower filling pressures than captopril. Both interventions reduced messenger ribonucleic acid expression of the profibrotic cytokine transforming growth factor-beta(1); neither effected the anti-inflammatory cytokine interleukin-10, and only captopril reduced the proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha). Expression of TNF-alpha was in cardiomyocytes. Both medications reduced circulating endothelin-1, angiotensin II and catecholamines, but only omapatrilat increased atrial natriuretic peptides.


CONCLUSIONS
This study indicates that both omapatrilat and captopril markedly improve post-MI survival, cardiac function and cardiac remodeling in the rat. It would appear that the addition of NEP inhibition to those of ACEIs does not result in significant further benefit after MI.
Lapointe
Nathalie
N
Division of Cardiology, University Health Network, Toronto General Hospital, Toronto, Ontario, Canada.
Blais
Charles
C
Adam
Albert
A
Parker
Thomas
T
Sirois
Martin G
MG
Gosselin
Hugues
H
Clément
Robert
R
Rouleau
Jean L
JL
D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology*; D000818:Animals; D002216:Captopril / Q000494:pharmacology*; D006439:Hemodynamics / Q000187:drug effects* / Q000502:physiology; D008297:Male; D009203:Myocardial Infarction / Q000473:pathology / Q000503:physiopathology*; D009206:Myocardium / Q000473:pathology; D018377:Neurotransmitter Agents / Q000097:blood*; D011480:Protease Inhibitors / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013841:Thiazepines / Q000494:pharmacology*; D016896:Treatment Outcome; D020257:Ventricular Remodeling / Q000187:drug effects* / Q000502:physiology
D000806:Angiotensin-Converting Enzyme Inhibitors; D018377:Neurotransmitter Agents; D011480:Protease Inhibitors; D011725:Pyridines; D013841:Thiazepines; C106266:omapatrilat; D002216:Captopril