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Is calcium a coronary vasoconstrictor in vivo?
G J Crystal1, X Zhou, M R Salem
1Department of Anesthesiology, Illinois Masonic Medical Center, University of Illinois College of Medicine, Chicago 60657-5193, USA. George.J.Crystal@uic.edu
Anesthesiology
|April 2, 1998
Summary
Calcium chloride (CaCl2) constricts coronary arteries in vivo, impairing blood flow regulation. Dobutamine, however, increases heart function without affecting coronary resistance vessels.
Area of Science:
- Cardiovascular Physiology
- Pharmacology
Background:
- Calcium's role in coronary vasoconstriction is debated in vivo.
- Understanding calcium's in vivo effects is crucial for cardiovascular research.
Purpose of the Study:
- To investigate the in vivo effects of calcium chloride (CaCl2) on coronary circulation and myocardial function.
- To compare the effects of CaCl2 with dobutamine, a known inotropic agent.
Main Methods:
- Anesthetized dogs underwent left anterior descending coronary artery perfusion.
- Myocardial shortening, coronary blood flow, and oxygen consumption were measured.
- Intracoronary infusions of CaCl2 and dobutamine were administered and compared.
Main Results:
- CaCl2 increased myocardial shortening and oxygen consumption, but coronary blood flow increases were insufficient, raising the oxygen extraction ratio.
- Dobutamine similarly increased myocardial shortening and oxygen consumption.
- Dobutamine-induced increases in coronary blood flow were proportional to oxygen demand, maintaining a constant oxygen extraction ratio.
Conclusions:
- Calcium chloride exhibits in vivo coronary vasoconstriction and positive inotropic effects, uncoupling blood flow from oxygen demand.
- Dobutamine acts as a positive inotropic agent with no direct effect on coronary resistance vessels in vivo.