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Effects of phosphoramidon, BQ 788, and BQ 123 on coronary and cardiac dysfunctions of the failing hamster heart.
- Source :
-
Journal of cardiovascular pharmacology [J Cardiovasc Pharmacol] 1998 Jul; Vol. 32 (1), pp. 12-20. - Publication Year :
- 1998
-
Abstract
- Coronary dysfunctions identified in the presence of chronic heart failure are an important pathophysiologic abnormality that influences the prognosis of the disease. Because the endothelin pathway plays a significant role in the increased peripheral vascular tone associated with heart failure, we hypothesized that the endothelin pathway may be involved in the abnormal coronary vasomotion associated with this pathologic condition. Experiments were carried out in failing hearts (UM-X7.1 cardiomyopathic hamsters, aged 225-250 days) and normal hearts (Syrian LVG hamsters, also aged 225-250 days). Isolated hearts were perfused at constant flow and exposed to the blocker of the generation of endothelin-1 (ET-1), phosphoramidon (10 microM infusion), as well as to the selective ET(A)-receptor antagonist BQ 123 (10 microM infusion) and to a selective ET(B)-receptor antagonist BQ 788 (1 microM infusion). Coronary and cardiac effects of exogenous ET-1 (0.01-100 pmol) were also studied. Phosphoramidon, BQ 788, and BQ 123 did not altered coronary perfusion pressure either in normal or in failing hearts, whereas cardiac contractility was significantly impaired in the presence of phosphoramidon and BQ 123. Coronary sensitivity to exogenous ET-1 did not demonstrate a significant difference between normal and failing hearts [median effective concentration (EC50), 7 pmol in failing hearts vs. 12 pmol in normal hearts; p = NS]. In the presence of exogenous ET-1, cardiac contractility was significantly increased in both groups. In normal hearts, the exogenous ET-1-induced increase in coronary perfusion pressure was completely antagonized by BQ 123, whereas combined administration of BQ 788 and BQ 123 was necessary to induce complete inhibition in failing hearts. The positive inotropic effect elicited by exogenous ET-1 (EC50) was completely abolished in the presence of BQ 123, whereas BQ 788 had no significant effect. Results indicate that the endothelin pathway does not play a significant role in the altered coronary vasomotion observed in this model of chronic heart failure. On the contrary, the endothelin pathway appears to participate in the maintenance of myocardial contractility. According to these observations, administration of an inhibitor of ET-1 synthesis, as well as the use of an ET(A)-receptor antagonist, may be contraindicated in the presence of poor left ventricular function because the endothelin pathway contributes significantly to the maintenance of cardiac contractility.
- Subjects :
- Animals
Blood Pressure drug effects
Coronary Circulation drug effects
Coronary Vessels physiopathology
Cricetinae
Electrocardiography drug effects
Endothelin-Converting Enzymes
Heart physiopathology
Mesocricetus
Receptor, Endothelin A
Receptor, Endothelin B
Aspartic Acid Endopeptidases antagonists & inhibitors
Coronary Vessels drug effects
Endothelin Receptor Antagonists
Glycopeptides pharmacology
Heart drug effects
Heart Failure physiopathology
Metalloendopeptidases antagonists & inhibitors
Oligopeptides pharmacology
Peptides, Cyclic pharmacology
Piperidines pharmacology
Protease Inhibitors pharmacology
Subjects
Details
- Language :
- English
- ISSN :
- 0160-2446
- Volume :
- 32
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Journal of cardiovascular pharmacology
- Publication Type :
- Academic Journal
- Accession number :
- 9676715
- Full Text :
- https://doi.org/10.1097/00005344-199807000-00003