Angiotensin-converting enzyme inhibition in infarct-induced heart failure in rats: bradykinin versus angiotensin II.
BACKGROUND
The beneficial effects of angiotensin-converting enzyme (ACE) inhibitors in the prevention of heart failure following myocardial infarction are widely accepted. However, the underlying mechanisms are still a matter of discussion. We therefore investigated the relative contribution of the breakdown of bradykinin and of the inhibition of angiotensin-II synthesis to the beneficial actions of ACE inhibitors in chronic heart failure following myocardial infarction.


METHODS
We compared the effects pretreatment with the ACE inhibitor moexipril with those of the type 1 angiotensin (AT1)-receptor antagonist losartan on structural and functional cardiac parameters after myocardial infarction in rats. In addition, the bradykinin B2-receptor antagonist icatabant was used to investigate the role of bradykinin in the cardioprotective effects of ACE inhibition. Rats underwent a sham operation or surgery to induce myocardial infarction. Treatment was started 1 week before myocardial infarction and continued for another 6 weeks after the procedure.


RESULTS
Moexipril reduced infarct size (100 +/- 9mm2 compared with 165 +/- 8mm2), the ratio of total heart weight to body weight (2.6 +/- 0.1 g/kg compared with 2.9 +/- 0.1 g/kg) and end-diastolic pressure (8.2 +/- 1.5 mmHg compared with 14.0 +/- 1.7 mmHg). All of these effects of the ACE inhibitor were blocked by concomitant treatment with icatibant. Losartan did not affect any of these cardiac parameters.


CONCLUSIONS
The cardioprotective effects of the ACE inhibitor moexipril administered before myocardial infarction in the present study were a result of the reduced breakdown of kinins rather than of the reduced synthesis of angiotensin II.
Stauss
H M
HM
Department of Pharmacology, University of Heidelberg, Germany.
Zhu
Y C
YC
Redlich
T
T
Adamiak
D
D
Mott
A
A
Kregel
K C
KC
Unger
T
T
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology / Q000627:therapeutic use; D000704:Analysis of Variance; D000804:Angiotensin II / Q000037:antagonists & inhibitors*; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D000818:Animals; D001713:Biphenyl Compounds / Q000494:pharmacology / Q000627:therapeutic use; D001920:Bradykinin / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors* / Q000494:pharmacology / Q000627:therapeutic use; D004195:Disease Models, Animal; D006321:Heart / Q000502:physiology; D006333:Heart Failure / Q000188:drug therapy* / Q000401:mortality / Q000473:pathology; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology; D007093:Imidazoles / Q000494:pharmacology / Q000627:therapeutic use; D007546:Isoquinolines / Q000494:pharmacology / Q000627:therapeutic use; D019808:Losartan; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D009203:Myocardial Infarction / Q000188:drug therapy* / Q000401:mortality / Q000473:pathology; D009206:Myocardium / Q000473:pathology; D009929:Organ Size; D051381:Rats; D017208:Rats, Wistar; D044005:Tetrahydroisoquinolines; D013777:Tetrazoles / Q000494:pharmacology / Q000627:therapeutic use
D000319:Adrenergic beta-Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D001713:Biphenyl Compounds; D007093:Imidazoles; D007546:Isoquinolines; D044005:Tetrahydroisoquinolines; D013777:Tetrazoles; D000804:Angiotensin II; C065679:icatibant; D019808:Losartan; D001920:Bradykinin; C058302:moexipril