July 1, 1967Circulation Research
Adrenergic Receptor Activity in the Coronary Arteries of the Unanesthetized Dog
Key result
Catecholamine injections demonstrated independent alpha- (vasoconstrictor) and beta- (vasodilator) adrenergic receptor activity in the coronary arteries of unanesthetized dogs.
Why the study?
Do alpha and beta adrenergic receptors independently mediate vasoconstriction and vasodilatation in the coronary arteries of unanesthetized dogs?
Population
Unanesthetized dogs
Comparison
Intravenous and intracoronary injections of… vs Baseline or unblocked state
Design
Preclinical
Authors
Discussion
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Implication
Hypothesis-generating in unanesthetized dogs; leaves open translation to human coronary vasoregulation.
Key Points
- To evaluate whether alpha- and beta-adrenergic receptors regulate coronary artery tone directly and independently of myocardial adrenergic responses in unanesthetized dogs.
- Administered intravenous and intracoronary injections of catecholamines, including epinephrine, norepinephrine, and phenylephrine, to unanesthetized dogs.
- Evaluated coronary vasoconstrictor and vasodilator responses before and after selective alpha- and beta-adrenergic receptor blockade.
- Beta-adrenergic receptor blockade unmasked alpha-adrenergic coronary vasoconstriction after intravenous and intracoronary administration of epinephrine and norepinephrine, which was eliminated by subsequent alpha-receptor blockade.
- Intravenous phenylephrine and select intracoronary doses of norepinephrine induced direct coronary vasoconstriction prior to beta-blockade.
- Beta-adrenergic activation caused prompt coronary vasodilation following catecholamine administration before any systemic or myocardial hemodynamic shifts occurred.
Structured PICO
Do alpha and beta adrenergic receptors independently mediate vasoconstriction and vasodilatation in the coronary arteries of unanesthetized dogs?
P
Population
Unanesthetized dogs
I
Intervention
Intravenous and intracoronary injections of catecholamines (epinephrine, norepinephrine, phenylephrine) with and without alpha- and beta-adrenergic receptor blockade
C
Comparator
Baseline or unblocked state
O
Outcome
Coronary vasoconstriction and vasodilatationsurrogate
This study provides physiological evidence of independent alpha- and beta-adrenergic receptor activity controlling vasomotor tone in the coronary arteries of unanesthetized dogs.
Cite This Study
Pitt et al. (1967) studied Unanesthetized dog (animal model). Intravenous and intracoronary injections of catecholamines and receptor blockers was evaluated on Coronary vasoconstriction and vasodilatation. Catecholamine injections demonstrated independent alpha- (vasoconstrictor) and beta- (vasodilator) adrenergic receptor activity in the coronary arteries of unanesthetized dogs.