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Endothelial cells regulate cardiac contractility
C Ramaciotti1, A Sharkey, G McClellan
1Department of Physiology, School of Medicine, University of Pennsylvania, Philadelphia.
Insights
Cardiac endothelial cells can modulate heart muscle contractions. Coronary venous effluent from a working heart alters cardiac trabecula contractions, indicating a role for endothelial cells in heart regulation.
Area of Science:
- Cardiovascular Physiology
- Endothelial Cell Biology
- Cardiac Muscle Mechanics
Background:
- Endothelial cells regulate vascular smooth muscle tone via vasoactive factors.
- The role of endothelial cells in modulating cardiac muscle contraction is not well understood.
Purpose of the Study:
- To investigate whether endothelial cells influence cardiac muscle contraction.
- To determine if cardiac tissue releases factors that modulate endothelial cell activity.
Main Methods:
- Isolated perfused working heart model to collect coronary venous effluent.
- Superfusion of isolated cardiac trabeculae with coronary effluent.
- Selective endothelial cell damage to assess their role in mediating effects.
Main Results:
- Coronary venous effluent reversibly altered the peak tension and duration of trabecula contractions.
- Damage to trabecula endothelial cells abolished the effect of the effluent.
- Effluent's effect varied with the metabolic and mechanical conditions of the donor heart.
Conclusions:
- Cardiac tissue releases substances into the coronary circulation.
- These substances induce endothelial cells to produce cardioactive factors.
- Endothelial cells play a role in the physiological regulation of cardiac contractility.
Abstract:
Endothelial cells lining the lumen of blood vessels contain the receptors for many substances that alter the contractile tone of smooth muscle in the walls of the blood vessels. In response to their interaction with the signal substances, the endothelial cells release vasoactive factors that modify the contractile state of the vascular smooth muscle. This study was conducted to determine if endothelial cells can also modulate the contraction of cardiac muscle cells and contribute to the physiological regulation of the heart. The venous effluent from the coronary circulation of an isolated perfused working heart was reoxygenated and used to superfuse a trabecula isolated from the right ventricle of another heart. The peak tension and the duration of the contraction of the trabecula were reversibly altered by the effluent fluid. The change in the contraction of the trabecula during its exposure to coronary effluent was inhibited by selectively damaging the endothelial cells in the trabecula before the application of the coronary effluent. The magnitude and direction of the effect of the coronary venous effluent were sensitive to the metabolic and mechanical conditions under which the isolated perfused heart was contracting at the time the effluent was collected. These observations indicate that cardiac tissue can release a substance or substances into the coronary circulation that induce the production of cardioactive factors by endothelial cells.