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Bradykinin degradation and relation to myocyte contractility
R S Krombach1, J H McElmuray, D M Gay
1Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC 29425, USA.
Journal of Cardiovascular Pharmacology and Therapeutics
|January 11, 2001
Summary
Bradykinin (BK) directly impairs left ventricular myocyte contractility. Angiotensin-converting enzyme (ACE) inhibition significantly mitigates this negative effect by influencing BK degradation within myocytes.
Area of Science:
- Cardiovascular Physiology
- Molecular Cardiology
- Pharmacology
Background:
- Exogenous bradykinin (BK) induces vasodilation and increases coronary blood flow, potentially benefiting cardiac disease.
- Angiotensin-converting enzyme (ACE) degrades BK into BK((1-7)), a pathway relevant to cardiovascular function.
Purpose of the Study:
- To investigate the direct effects of BK and its metabolite BK((1-7)) on myocyte contractility.
- To determine if ACE inhibition modulates the impact of BK on myocyte function.
Main Methods:
- Isolated adult porcine left ventricular (LV) myocytes were used.
- Myocyte contractility was assessed in the presence of BK, BK((1-7)), and after ACE inhibition (benazaprilat).
- ACE activity and BK degradation in myocyte preparations were measured.
Main Results:
- BK (10(-8) mol/L) reduced myocyte velocity of shortening by over 15%, and BK((1-7)) (10(-8) mol/L) by 8%.
- ACE inhibition blunted the negative effect of BK on myocyte contractility by over 60%.
- Significant ACE activity and BK degradation were observed in LV myocytes, influenced by ACE inhibition.
Conclusions:
- BK exerts a direct negative effect on left ventricular myocyte contractility.
- This effect appears to be mediated by BK proteolysis at the myocyte sarcolemma.
- ACE inhibition plays a role in modulating BK's impact on myocyte function.